JP7203187B2 - WIRE GRID POLARIZATION ELEMENT, METHOD FOR MANUFACTURING WIRE GRID POLARIZATION ELEMENT, PROJECTION DISPLAY DEVICE, AND VEHICLE - Google Patents

Description

INDUSTRIAL APPLICABILITY The present invention provides a wire grid polarizing element that has excellent polarizing properties, does not cause deterioration in heat dissipation and manufacturing costs, and has excellent transmittance for obliquely incident light and incident light with a wide range of incident angles. and a method for manufacturing a wire grid polarizing element, a projection display device excellent in polarization characteristics and heat resistance, and a vehicle equipped with the projection display device.

As one type of projection display device, in recent years, many vehicle head-up display devices have been developed that display images on a transflective plate (hereinafter collectively referred to as a "display surface") such as a vehicle windshield or a combiner. It is A vehicle head-up display device is, for example, a video display device that is arranged on a dashboard of a vehicle, projects video light onto a windshield, and displays driving information as a virtual image. The driver can visually recognize the virtual image at the same time as the scenery through the windshield. has the advantage of being less

However, since the head-up display device described above emits the display image from below toward the windshield surface (upper), sunlight enters in the direction opposite to the emission direction of the display image and enters the display element. something happened. A head-up display device is often provided with a reflector for reflecting and enlarging a display image for the purpose of miniaturization and enlargement of a display image. In such a case, sunlight incident on the head-up display device is condensed in the vicinity of the display element, and the heat may cause deterioration or failure of the display element.

Therefore, for the purpose of preventing sunlight from entering the display element, a technique has been developed in which a reflective polarizing element is provided in the head-up display device. For example, Patent Literature 1 discloses a head-up display device in which a reflective polarizing element (wire grid polarizing plate) is provided between a reflector and a display element.

Here, as the polarizing element provided in the head-up display device as described above, for example, a polarizing element made of a birefringent resin or a wire in which a plurality of conductors (thin metal wires) extend parallel to each other on a transparent substrate. A grid-type polarizing element, a polarizing element made of a cholesteric phase liquid crystal, and the like are included. Among these, wire grid type polarizing elements with excellent polarization characteristics are often used. In the wire grid type polarizing element, a wire grid is formed in which conductor wires made of metal or the like are arranged in a grid pattern at a specific pitch. By setting the arrangement pitch of the wire grid to a pitch smaller than the wavelength of the incident light (eg, visible light) (eg, 1/2 or less), the electric field vector component vibrating parallel to the conductor wires can be reflected, and most of the light of the electric field vector component perpendicular to the conductor wire can be transmitted. As a result, the wire grid type polarizing element can be used as a polarizing element that produces a single polarized light, and can reflect and reuse light that does not pass through, which is desirable from the viewpoint of effective use of light. The polarizing element used here includes a polarizing element that can be used as a polarizing beam splitter that splits incident light into S-polarized light and P-polarized light.

As such a wire grid type polarizing element, for example, Patent Document 2 discloses a resin substrate having lattice-shaped convex portions, a dielectric layer provided so as to cover the lattice-shaped convex portions of the resin substrate, and a dielectric A wire grid polarizer is disclosed comprising metal wires disposed on a layer.

Further, in Patent Document 3, a base material made of resin or the like and provided with a concavo-convex structure extending in a specific direction on the surface, and a conductor provided so as to be unevenly distributed on one side surface of the convex part of the concavo-convex structure and a wire grid polarizer is disclosed. In the wire grid polarizing plate, the pitch, which is the interval between two adjacent protrusions, and the height of the protrusions are adjusted in a cross-sectional view in the direction perpendicular to the extending direction of the uneven structure.

Furthermore, Patent Document 4 discloses a projection type image display device using a reflective liquid crystal display element and a reflective wire grid polarizing plate as a polarized beam splitter. In the projection type image display device using the reflective liquid crystal display device described in Patent Document 4, the reflective wire grid polarizing plate is arranged at an angle of about 45° with respect to the optical axis of the light emitted from the light source. Emitted light from the light source is separated into first polarized light (reflected light) and second polarized light (transmitted light) by entering the reflective wire grid at an oblique incident angle of about 45°. Next, the first polarized light reflected by the reflective wire grid polarizer is modulated and reflected by the reflective liquid crystal display element to become the second polarized light, and the second polarized light is transmitted through the reflective wire grid polarizer. and projected.

Further, Patent Document 5 discloses a vehicle headlamp using a reflective wire grid polarizing plate as a polarizing beam splitter. In the vehicle headlamp described in Patent Document 5, the reflective wire grid polarizing plate is also arranged at an angle of about 45° with respect to the optical axis of the light emitted from the light source. The emitted light from the light source enters the reflective wire grid at an oblique incident angle of about 45°, and is separated into the first polarized light (reflected light) and the second polarized light (transmitted light).

When the reflective wire grid polarizing plate is arranged at an angle of about 45° with respect to the light emitted from the light source, such as the projection type image display device described in Patent Document 4 and the vehicle headlight described in Patent Document 5. , the incident light is not only incident on the reflective wire grid polarizer at a single angle of incidence of 45°, but also at angles of incidence on the order of 45°±15°.

Further, Patent Document 6 discloses a wire grid polarization beam splitter in which a plurality of grids made entirely of silver or aluminum protrude from a substrate.

Further, Patent Document 7 discloses a wire grid polarizer having a light-transmissive substrate, an underlying layer, and thin metal wires. In the wire grid polarizer disclosed in Patent Document 7, the light-transmissive substrate has a plurality of ridges formed on the surface in parallel with each other at a predetermined pitch. The base layer is made of a metal oxide present at least on the top of the ridges, and the fine metal wires are made of a metal layer on the surface of the base layer and at least on the ridges of the ridges.

JP 2018-72507 A JP 2008-83657 A JP 2017-173832 A JP 2004-184889 A JP 2019-50134 A Japanese Patent Publication No. 2003-508813 WO2010/005059

By the way, the temperature environment generally required for equipment used in vehicles is -40 to 105°C, but especially in the summer, such as the head-up display mounted on the dashboard of the car, it is used in a high temperature environment. When considering that it will be used, high heat resistance and heat dissipation are required. In this regard, the wire grid polarizing plates described in Patent Documents 1 to 3 are required to be further improved in terms of heat resistance and heat dissipation. Further, in order to brightly illuminate a road at night with the vehicle headlamp described in Patent Document 5, it is essential to increase the brightness of the vehicle headlamp. Therefore, the wire grid polarizing plate described in Patent Document 5 is required to have high heat resistance and heat dissipation properties against the heat from the light source.

Furthermore, conventional wire grid polarizers have problems such as high manufacturing costs and unsuitability for mass production, because the irregularities on the surface are generally formed by photolithography or etching.

Then, in a projection display device such as a head-up display device, when the reflective wire grid polarization element is used as a polarization beam splitter to separate the first polarized light (S polarized light) and the second polarized light (P polarized light), Both the reflectance for one polarized light and the transmittance for the second polarized light are required to be high. Here, the product (Tp×Rs) of the reflection axis reflectance (Rs) of the first polarized light (S polarized light) and the transmission axis transmittance (Tp) of the second polarized light (P polarized light) is the polarization separation characteristic When used as an index of , the higher the value of this Tp×Rs, the better. However, depending on the type of projection display device to which the polarizing beam splitter is applied, the handling of polarized light in the polarizing beam splitter differs. It may be.

In addition, the incident angle of the incident light to the polarizing beam splitter is not only a single angle of 45°, but spreads over a range of about 45°±15° around 45°. incident on the beam splitter. For this reason, the polarizing beam splitter is required to exhibit good polarization splitting characteristics for obliquely incident light regardless of the incident angle of the incident light (hereinafter referred to as obliquely incident light). be done.

However, in the structure of the conventional reflective wire grid polarizer, as the incident angle of the obliquely incident light increases, the transmission axis transmittance (Tp) of the second polarized light (P-polarized light) decreases. There is a problem that the polarization splitting characteristics for light are degraded. For example, as described in Patent Document 6, the entire convex portion of the grid is composed of a conductor, or as described in Patent Document 3, a conductor (reflecting film) unevenly distributed on one side of the convex portion of the wire grid ) is provided. In these cases, as the incident angle of the obliquely incident light increases, the transmission axis transmittance (Tp) of the second polarized light (P-polarized light) decreases, and the above Tp×Rs decreases. As a result, the light utilization efficiency deteriorates, and image quality deterioration such as luminance unevenness becomes a problem. Therefore, in the structure of the conventional reflective wire grid polarizing element described in Patent Documents 3, 6, etc., there is room for improvement in the polarization separation characteristics for obliquely incident light with a large and wide range of incident angles.

Further, Patent Document 7 describes that the coverage of the side surface of the ridge with the metal layer (reflective film) is preferably 50% or more, 70% or more, and particularly preferably 100%. there is Furthermore, in Patent Document 7, when the area of the metal layer covering the side surface of the ridge is increased, a lower S-polarized reflectance can be realized for the light incident from the back side of the wire grid polarizer, and the surface It is described that S-polarized light incident from the side can be efficiently reflected, and that the wire grid polarizer exhibits high polarization separation ability.

However, when the area of the metal layer covering the side surfaces of the ridges of the wire grid is large as described in Patent Document 7, when the incident angle of the oblique incident light is large, especially when it is 45 to 60°, The transmission axis transmittance (Tp) of the second polarized light (P-polarized light) is significantly reduced, and the Tp×Rs is also significantly reduced. As a result, the light utilization efficiency deteriorates, and image quality deterioration such as luminance unevenness becomes a problem. Therefore, even with the structure of the wire grid polarizer described in Patent Document 7, there is room for improvement in the polarization splitting characteristics for obliquely incident light with a large and wide range of incident angles.

As described above, it is desired to have excellent polarization separation characteristics for obliquely incident light with a large and wide range of incident angles. In particular, sufficient transmittance cannot be ensured for light with a large incident angle of 45° or more, and further improvements have been desired in transmittance for obliquely incident light and polarization separation characteristics.

Therefore, the present invention has been made in view of such circumstances, and provides a wire grid polarizing element that is excellent in heat dissipation and has excellent transparency and polarization separation characteristics for obliquely incident light with a wide range of incident angles, and the polarizing element. and a projection display device and a vehicle equipped with the polarizing element.

As a result of earnest research to solve the above problems, the inventors have found the following findings. First, the substrate of the wire grid polarizing element is formed of a transparent inorganic material, and the grid structure provided on the substrate is integrally formed of a transparent organic material. As a result, the wire grid polarizing element can have a hybrid structure composed of an organic material and an inorganic material. As a result, the heat dissipation of the wire grid polarizing element can be greatly improved.

Furthermore, as the grid structure, a grid structure is used in which a base portion provided along the surface of the substrate and a plurality of ridges protruding from the base portion are integrally formed. As a result, the grid structure can be formed by a technique such as nanoimprinting, so that the manufacturing cost of the grid structure can be reduced and mass production is possible as compared with the case of using photolithography technique or etching technique.

Furthermore, when a functional film such as a reflective film that reflects light or an absorption film that absorbs light is provided on the ridges of the grid structure, the range and form of coverage of the ridges with the functional film can be suitably selected. adjust. That is, the tip of the ridge and the upper side of one or both side surfaces are covered with the functional film, while the lower side of the ridge and the surface of the base are not covered with the functional film. to open. The functional film has a rounded shape that bulges in the width direction of the protruding portion so as to cover the tip of the protruding portion and the upper side of the side surface. Furthermore, the ridges are adjusted so that the maximum width (W _MAX ) of the grid, which is the sum of the ridges and the functional film covering the ridges, is equal to or greater than the width (W _B ) of the bottom of the ridges. and adjust the shape and size of the functional membrane. Furthermore, the range in which the functional film covers the side surface of the ridge is limited to a specific range on the upper side of the side surface (for example, a range of 25% or more and 80% or less of the height (H) of the ridge). is preferred.

As a result, even when obliquely incident light with a large and wide range of incident angles is incident on the wire grid polarizing element, the transmittance (Tp) of the second polarized light (P polarized light) in the wire grid polarizing element It is possible to suppress the decrease depending on the angle. Therefore, the product (Tp×Rs) of the reflection axis reflectance (Rs) of the first polarized light (S-polarized light) and the transmission axis transmittance (Tp) of the second polarized light (P-polarized light) in the wire grid polarizer is , can be maintained at a high value. Therefore, when the wire grid polarizing element is used as, for example, a polarizing beam splitter, it is possible to obtain sufficient transmittance and polarization separation characteristics even for obliquely incident light with a large incident angle and a wide range.

The present inventor has conceived the following invention based on the above findings.

In order to solve the above problems, according to one aspect of the present invention,
A hybrid wire grid polarizing element made of an inorganic material and an organic material,
a substrate made of the inorganic material;
a grid structure made of the organic material and integrally formed with a base provided on the substrate and a plurality of ridges protruding from the base;
a functional film made of a metal material and covering a part of the ridge;
with
The protruding portion has a tapered shape in which the width becomes narrower as the distance from the base portion increases,
The functional film covers the tip of the ridge and the upper side of at least one side surface, and does not cover the lower sides of both side surfaces of the ridge and the base portion,
The surface of the functional film covering the ridge is rounded and bulges in the width direction of the ridge, and the maximum width (W _MAX ) of the functional film covering the ridge is , the width (W _B ) of the ridge portion of the portion not covered with the functional film at a position 20% above the height of the ridge portion from the bottom of the ridge portion ;
The coverage ratio (Rc) of the side surface of the ridge portion with the functional film is the height of the portion of the side surface of the ridge portion covered with the functional film ( Hx), when
The wire grid polarizing element is provided , wherein the coverage (Rc) is 30% or more and 70% or less .

Even if the product (Tp×Rs) of the transmission axis transmittance (Tp) and the reflection axis reflectance (Rs) of incident light with an incident angle of 45° to the wire grid polarizing element is 70% or more good.

The height (H) of the ridge may be 160 nm or more.

A thickness (Dt) of the functional film covering the tip of the protruding portion may be 5 nm or more.

A thickness (Ds) of the functional film covering the side surface of the protruding portion may be 10 nm or more and 30 nm or less.

The thickness (TB) of the base portion may be 1 nm or more.

A cross-sectional shape of the ridges in a cross section perpendicular to the direction of the reflection axis of the wire grid polarizing element may be trapezoidal, triangular, bell-shaped, or elliptical, the width of which narrows with increasing distance from the base.

A protective film may be further provided so as to cover at least the surface of the functional film.

The protective film may include a water-repellent coating or an oil-repellent coating.

The functional film may further have a dielectric film.

When θ is 30° or more and 60° or less,
The difference between the transmission axis transmittance (Tp(+)) of incident light with an incident angle of +θ and the transmission axis transmittance (Tp(−)) of incident light with an incident angle of −θ with respect to the wire grid polarizing element may be within 3%.

The functional film may be a reflective film that reflects incident light.

The wire grid polarizing element may be a polarizing beam splitter that splits obliquely incident light into first polarized light and second polarized light.

In order to solve the above problems, according to another aspect of the present invention,
A method for manufacturing a hybrid wire grid polarizer made of an inorganic material and an organic material, comprising:
forming a grid structure material made of the organic material on the substrate made of the inorganic material;
a step of forming a grid structure in which a base portion provided on the substrate and a plurality of ridges projecting from the base portion are integrally formed by performing nanoimprinting on the grid structure material;
a step of forming a functional film that covers a portion of the ridge using a metal material;
including
In the step of forming the grid structure, forming the protruding portion having a tapered shape in which the width becomes narrower as the distance from the base portion increases,
In the step of forming the functional film,
The functional film covers the tip and the upper side of at least one side surface of the protruding portion, and covers the protruding portion without covering the lower side of both side surfaces of the protruding portion and the base portion. The surface of the functional film that wraps is rounded and bulges in the width direction of the ridge, and the maximum width (W _MAX ) of the functional film that covers and wraps the ridge extends from the bottom of the ridge. At a position 20% above the height of the protruded streak, the width (W B ) of the protruded streak is equal to or greater than the width (W _B ) of the protruded streak at the portion not covered with the functional film. When the coverage ratio (Rc) of the side surface is the ratio of the height (Hx) of the portion of the side surface of the ridge covered with the functional film to the height (H) of the ridge, A method for manufacturing a wire grid polarizing element is provided, in which the functional film is formed so that the coverage (Rc) is 30% or more and 70% or less .

In the step of forming the functional film, film formation may be alternately performed from a plurality of directions on the ridges by sputtering or vapor deposition.

In order to solve the above problems, according to another aspect of the present invention,
a light source;
a polarizing beam splitter arranged so that the incident light from the light source is incident at an incident angle within a predetermined range including 45° and splitting the incident light into a first polarized light and a second polarized light;
arranged so that the first polarized light reflected by the polarizing beam splitter or the second polarized light transmitted through the polarizing beam splitter is incident, and the incident first polarized light or the second polarized light A reflective liquid crystal display element that reflects and modulates the
a lens arranged so that the first polarized light or the second polarized light reflected and modulated by the reflective liquid crystal display element is incident through the polarizing beam splitter;
with
A projection display apparatus is provided, wherein the polarizing beam splitter is composed of the wire grid polarizing element.

The incident angle in the predetermined range may be 30° or more and 60° or less.

A heat dissipation member may be provided around the wire grid polarization element.

In order to solve the above problems, another aspect of the present invention provides a vehicle including the projection display device.

ADVANTAGE OF THE INVENTION According to this invention, the wire grid polarizing element which is excellent in heat dissipation, and has the excellent polarization separation characteristic with respect to the obliquely incident light of a wide range of incident angles can be provided.

1 is a cross-sectional view schematically showing a wire grid polarizing element according to one embodiment of the present invention; FIG. It is a top view which shows typically the wire-grid polarizing element which concerns on the same embodiment. FIG. 5 is a cross-sectional view schematically showing a specific example of a tapered shape of the protruded streaks of the grid structure according to the same embodiment. FIG. 5 is a cross-sectional view schematically showing a specific example of the shape of recesses of the grid structure according to the embodiment; It is a sectional view showing typically the wire grid polarizing element concerning the embodiment. FIG. 4 is a cross-sectional view schematically showing a specific example of the shape of the reflective film according to the same embodiment; FIG. 4 is a cross-sectional view schematically showing a polarizing element covered with a protective film according to the embodiment; FIG. 10 is a cross-sectional view schematically showing a modification of the polarizing element covered with a protective film according to the same embodiment. FIG. 3 is a perspective view schematically showing a polarizing element provided with a heat radiating member according to the same embodiment; It is the photograph which shows the actual grid structure and reflective film which concern on the same embodiment. It is process drawing which shows the manufacturing method of the wire grid polarizing element which concerns on the same embodiment. It is process drawing which shows the manufacturing method of the conventional wire grid polarizing element. It is process drawing which shows the manufacturing method of the master recording which concerns on the same embodiment. FIG. 2 is a schematic diagram showing a head-up display device as an example of the projection display device according to the embodiment; FIG. 3 is a schematic diagram showing a first specific example of the projection display device according to the same embodiment; FIG. 5 is a schematic diagram showing a second specific example of the projection display device according to the same embodiment; FIG. 10 is a schematic diagram showing a third specific example of the projection display device according to the same embodiment; FIG. 5 is a diagram for explaining a polarizing element according to Conventional Example 1; FIG. 10 is a diagram for explaining a polarizing element according to Conventional Example 2; FIG. 10 is a diagram for explaining a polarizing element according to Conventional Example 3; FIG. 4 is a diagram for explaining a polarizing element according to Example 1; FIG. 5 is a diagram for explaining the results of comparison between Example 1 and Conventional Example 2; FIG. 10 is a diagram for explaining a polarizing element according to Example 2; FIG. 11 is a diagram for explaining a polarizing element according to Example 3; FIG. 11 is a diagram for explaining a polarizing element according to Example 4; FIG. 11 is a diagram for explaining a polarizing element according to Example 5; FIG. 11 is a diagram for explaining a polarizing element according to Example 6; FIG. 11 is a diagram for explaining a polarizing element according to Example 7; FIG. 11 is a diagram for explaining a polarizing element according to Example 8; FIG. 12 is a diagram for explaining the results of comparison between Example 9 and Conventional Example 4; FIG. 12 is a diagram for explaining the results of comparison between Example 9 and Conventional Example 4;

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the present specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description. For convenience of explanation, the state of each member disclosed in each of the following drawings may be schematically represented in scales and shapes that are different from the actual ones.

<1. Overview of wire grid polarizer>
First, an overview of a wire grid polarizer 1 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2 and the like. FIG. 1 is a cross-sectional view schematically showing a wire grid polarizing element 1 according to this embodiment. FIG. 2 is a plan view schematically showing the wire grid polarization element 1 according to this embodiment.

The wire grid polarizing element 1 according to this embodiment is a reflective polarizing element and a wire grid polarizing element. The wire grid polarizing element 1 may be, for example, a plate-like wire grid polarizing plate. A wire grid polarizing plate is a wire grid polarizing plate having a plate shape. The wire grid polarizing plate may have, for example, a flat plate shape or a curved plate shape. That is, the surface of the wire grid polarizing element 1 (the surface on which light is incident) may be flat or curved. In the following, an example in which the wire grid polarizing element 1 according to the present embodiment is a flat wire grid polarizing plate will be described, but the wire grid polarizing element of the present invention is not limited to such an example. etc., it can have any shape.

The wire grid polarizing element of the present invention may be used, for example, as a polarizer that transmits only light vibrating in a specific direction, or may be used as a first polarized light (S polarized light). It may also be used as a polarizing beam splitter to split into a second polarization (P-polarization). An example in which the wire grid polarization element 1 according to this embodiment is used as a polarization beam splitter will be mainly described below.

As shown in FIGS. 1 and 2, a wire grid polarizer 1 (hereinafter sometimes referred to as "polarizer 1") includes a transparent substrate 10, a transparent grid structure 20, and an opaque function. a film (eg, a reflective film 30).

In this specification, the term “transparent” means that the transmittance of light with a wavelength λ belonging to the usage band (for example, the visible light band, the infrared light band, or the visible light and infrared light band) is It means high, for example, it means that the transmittance of the light is 70% or more. The wavelength band of visible light is, for example, 360 nm or more and 830 nm or less. The wavelength band of infrared light (infrared rays) is larger than the wavelength band of visible light, and is, for example, 830 nm or more. From the viewpoint of a suitable wavelength range of visible light projected as a display image, the wavelength λ of the use band in the polarizing element 1 according to the present embodiment is preferably, for example, 400 nm or more and 800 nm or less, and 420 nm or more and 680 nm. The following are more preferable. Since the polarizing element 1 according to the present embodiment is made of a material transparent to light in the working band, the polarization characteristics of the polarizing element 1, light transmittance, and the like are not adversely affected.

The substrate 10 is made of a transparent inorganic material such as glass. The substrate 10 is a flat substrate having a predetermined thickness TS.

The grid structure 20 is made of a transparent organic material, for example, an organic resin material such as an ultraviolet curable resin or a thermosetting resin having excellent heat resistance. The grid structure 20 has an uneven structure for realizing the polarizing function of the polarizing element 1 . Specifically, the grid structure 20 has a base portion 21 provided along the surface of the substrate 10 and a plurality of ridges 22 protruding from the base portion 21 in a grid pattern. The base portion 21 and the plurality of ridges 22 of the grid structure 20 are integrally formed using the same organic material.

The base portion 21 is a thin film having a predetermined thickness TB, and is laminated over the entire main surface (XY plane shown in FIGS. 1 and 2) of the substrate 10 . The thickness TB of the base portion 21 is preferably substantially the same thickness over the entire main surface of the substrate 10, but may not be exactly the same thickness. may fluctuate with some error. For example, TB may vary by about ±3 μm with respect to the reference thickness of 6 μm. In this manner, the thickness TB of the base portion 21 is determined by allowing for molding errors when the base portion 21 is molded by imprinting or the like.

The plurality of ridges 22 are arranged on the base portion 21 at equal intervals with a predetermined pitch P in the X direction. In addition, the pitch P is the formation interval of the plurality of ridges 22 arranged in the X direction of the polarizing element 1 . The plurality of ridges 22 are arranged in a grid pattern so as to extend in parallel to each other in the Y direction. A predetermined gap is formed between two ridges 22 adjacent to each other in the X direction. This gap serves as an entrance path for incident light. Each protruding portion 22 is a wall-like protruding portion protruding so as to protrude in a predetermined direction (the Y direction shown in FIGS. 1 and 2). The height (H) in the Z direction and the width (W _T , W _B ) in the X direction of the plurality of ridges 22 are substantially the same. The longitudinal direction (Y direction) of the ridges 22 is the direction of the reflection axis of the polarizer 1 , and the width direction (X direction) of the ridges 22 is the direction of the transmission axis of the polarizer 1 .

A functional film is a film for imparting a predetermined function to the grid structure 20 of the polarizing element 1 . The functional film is made of, for example, an opaque metal material, and is provided so as to partially cover the ridges 22 of the grid structure 20 . The functional film may be, for example, a reflective film 30 having a function of reflecting incident light incident on the polarizing element 1, or an absorption film (not shown) having a function of absorbing the incident light. or a film having other functions. In this embodiment, an example in which the functional film is the reflective film 30 will be described, but the functional film of the present invention is not limited to the reflective film 30 .

The reflective film 30 is, for example, a thin film made of a metal material (such as metal or metal oxide) such as aluminum or silver. The reflective film 30 is formed to cover at least the top of the ridge 22 . The reflective film 30 may be composed of a metal film that functions as fine metal wires of a wire grid. The reflective film 30 has a function of reflecting incident light entering the grid structure 20 .

The ridges 22 of the grid structure 20 and the reflective film 30 constitute the grid of the wire grid polarizer 1 . The pitch P in the X direction of the plurality of ridges 22 in the grid structure 20 (that is, the arrangement pitch of the grid) is a pitch smaller than the wavelength λ of the incident light (for example, visible light) (for example, 1/2). below). As a result, the polarizing element 1 reflects most of the light (S-polarized light) of the electric field vector component vibrating in the direction (reflection axis direction: Y direction) parallel to the reflecting film 30 (conductor wire) extending in the Y direction. , the light (P-polarized light) of the electric field vector component oscillating in the direction (transmission axis direction: X direction) perpendicular to the reflective film 30 (conductor wire) can be almost transmitted.

As described above, the wire grid polarizing element 1 according to the present embodiment includes the grid structure 20 having a fine uneven structure and the functional film (for example, In combination with the reflective film 30), a polarizing function is realized. The substrate 10 of the wire grid polarizing element 1 is made of an inorganic material such as glass having excellent heat resistance, and the grid structure 20 is made of an organic resin material having heat resistance. Thus, the wire grid polarizing element 1 according to this embodiment is a hybrid polarizing element that combines organic and inorganic materials. Therefore, heat can be efficiently released from the grid structure 20 having a small thermal resistance R [m ² ·K/W] to the substrate 10, so that heat dissipation is excellent. Therefore, the hybrid-type wire grid polarizing element 1 according to the present embodiment has excellent heat resistance and heat dissipation compared to conventional film-type polarizing elements (heat resistance: about 100 ° C.) made only of organic materials. , for example, has heat resistance in a high temperature environment up to about 200°C. Therefore, it is possible to maintain a good heat dissipation effect while realizing excellent polarization characteristics.

Furthermore, the wire grid polarizer 1 according to this embodiment may include a protective film 40 (see FIGS. 7 and 8) that covers the surface of the grid structure 20 . The protective film 40 is made of an inorganic material, for example a dielectric material such as _SiO2 . The protective film 40 may be laminated on the entire surface of the wire grid polarization element 1 so as to cover all the surfaces of the base portion 21, the ridges 22 and the reflective film 30 of the grid structure 20 (see FIG. 7). .). By providing such a protective film 40, the advantageous effect of further reducing the thermal resistance R of the polarizing element 1 can be obtained, so that excellent polarizing characteristics can be achieved while maintaining a better heat radiation effect.

Further, as described above, the grid structure 20 in which the base portion 21 and the ridge portion 22 are integrally configured can be manufactured using a printing technique such as nanoimprinting. can be realized. Therefore, the cost and labor required for manufacturing the grid structure 20 can be reduced compared to the case of manufacturing using photolithography technology or etching technology. Therefore, the hybrid polarizing element 1 according to the present embodiment has the advantage that the manufacturing cost can be significantly reduced and the unit price of the wire grid polarizing element 1 can be reduced compared to the conventional polarizing element made of only inorganic materials. There is

On the other hand, the conventional film-type organic polarizing plate uses many organic materials, and the thickness of the substrate (base film), double-sided tape (OCA: Optically Clear Adhesive), and grid structure becomes large. It is considered that the heat dissipation property and the heat resistance are inferior to those of the hybrid type polarizing element 1 according to the above.

In the wire grid polarization element 1 according to the present embodiment, the grid composed of the ridges 22 of the grid structure 20 and the reflective film 30 has a special tree shape as shown in FIG. 1 (details will be described later). )have. As a result, even when light is incident obliquely on the polarizing element 1 at a wide range of large incident angles θ (for example, 30 to 60°), the second polarized light transmitted through the polarizing element 1 ( P-polarized light) transmittance (that is, transmission axis transmittance Tp) can be suppressed from decreasing depending on the incident angle θ of the obliquely incident light. Therefore, the product (Tp×Rs) of the reflectance (that is, the reflection axis reflectance Rs) of the first polarized light (S polarized light) reflected by the wire grid polarizer 1 and the transmission axis transmittance Tp is, for example, 70%. can be maintained at a higher value than Therefore, the polarizing element 1 according to the present embodiment has excellent polarization separation characteristics represented by Tp×Rs, and polarizes obliquely incident light into S-polarized light (reflected light) and P-polarized light (transmitted light). can be preferably separated. Therefore, the polarizing element 1 according to the present embodiment can obtain sufficient transmittance and polarization separation characteristics even for obliquely incident light with a large incident angle θ and in a wide range.

As described above, the wire grid polarizing element 1 according to the present embodiment has excellent heat resistance and heat dissipation, can reduce manufacturing costs, and has transparency and polarization separation for obliquely incident light with a wide range of large incident angles θ. Excellent characteristics. Therefore, the wire grid polarizing element 1 according to this embodiment can be suitably applied as various parts of various products. For example, the polarizing element 1 can be applied to a polarizing beam splitter installed in a smart display. The polarizing element 1 can be applied to a head-up display (HUD), a polarizing element for dealing with heat from sunlight, a polarizing element for dealing with heat from an LED light source, a polarizing reflecting mirror, and the like. Furthermore, the polarizing element 1 can also be applied to a polarizing beam splitter installed in a headlight such as a variable light distribution headlamp (ADB). The polarizing element 1 can also be applied to a lens-integrated retardation element, a lens-integrated polarizing element, etc. installed in various devices for augmented reality (AR) or virtual reality (VR).

<2. Components of Wire Grid Polarizing Element>
Next, the components of the wire grid polarization element 1 according to this embodiment will be described in detail with reference to FIGS. 1 and 2. FIG.

<2.1. Substrate>
As shown in FIG. 1, the wire grid polarizer 1 according to this embodiment includes a transparent substrate 10. As shown in FIG. The substrate 10 is made of an inorganic material that is transparent and has a certain degree of strength.

The material of the substrate 10 is preferably an inorganic material such as various types of glass, quartz, crystal, sapphire, etc., from the viewpoint of obtaining better heat dissipation and heat resistance, and has a thermal conductivity of 1.0 W/m. • An inorganic material with K or more is more preferable, and an inorganic material with 8.0 W/m·K or more is even more preferable.

Moreover, the shape of the substrate 10 is not particularly limited, and can be appropriately selected according to the performance required for the polarizing element 1 and the like. For example, it can be configured to have a plate shape or a curved surface. Moreover, from the viewpoint of not affecting the polarization characteristics of the polarizing element 1, the surface of the substrate 10 can be made flat. Further, the thickness TS of the substrate 10 is also not particularly limited, and can be in the range of 0.02 to 10.0 mm, for example.

<2.2. grid structure>
As shown in FIGS. 1 and 2, the polarizing element 1 according to the present embodiment includes a grid structure 20 having the base portion 21 and the grid-shaped ridges 22 on the substrate 10 . The grid structure 20 can obtain desired polarization characteristics by providing a reflective film 30 described later on the ridges 22 .

When light enters the polarizing element 1 from the surface side where the grid structure 20 is formed, part of the incident light is reflected by the reflective film 30 . Of the light incident on the reflective film 30 , the direction perpendicular to the longitudinal direction of the ridge 22 (that is, the extending direction of the ridge 22 = reflection axis direction: Y direction) (that is, the width direction of the ridge 22 = Light having an electric field component in the transmission axis direction (X direction) is transmitted through the polarizing element 1 with high transmittance. On the other hand, light having an electric field component in a direction parallel to the longitudinal direction of the ridges 22 (that is, the extending direction of the ridges 22 = reflection axis direction: Y direction) among the lights incident on the reflective film 30 is Most of the light is reflected by the reflective film 30 . Therefore, in this embodiment, by having the grid structure 20 partially covered by the reflective film 30, a single polarization can be created. A similar polarizing effect can be obtained for the light incident from the back side of the substrate 10 as well.

The grid structure 20 has a base portion 21 as shown in FIG. The base portion 21 is a thin film provided along the surface of the substrate 10 and is a portion for supporting the ridge portion 22 . The base portion 21 is inevitably formed when the concavo-convex structure (ridge portion 22) of the grid structure 20 is formed by nanoimprinting or the like. The base portion 21 and the ridge portion 22 are integrally formed of the same material. Moreover, since the grid structure 20 has the base portion 21 , the strength of the ridges 22 can be increased compared to the case where the ridges 22 are formed directly on the substrate 10 . Therefore, the durability of the grid structure 20 can be enhanced. Furthermore, since the base portion 21 is in close contact with the substrate 10 over the entire surface, the peeling resistance of the grid structure 20 can be enhanced.

Although the thickness TB of the base portion 21 is not particularly limited, it is preferably 1 nm or more, more preferably 10 nm or more, from the viewpoints of more reliable support of the ridges 22 and easy imprint molding. It is more preferable to have From the viewpoint of ensuring good heat dissipation, the thickness TB of the base portion 21 is preferably 50 μm or less, more preferably 30 μm or less.

Furthermore, the grid structure 20 has a plurality of ridges 22 protruding from the base 21, as shown in FIGS. The ridges 22 extend along the reflection axis direction (Y direction) of the polarizing element 1 according to this embodiment. A plurality of ridges 22 are arranged at a predetermined pitch in the X direction and are arranged at predetermined intervals from each other to form a grid-like concave-convex structure.

Here, as shown in FIG. 1 , in a longitudinal section (XZ section) perpendicular to the reflection axis direction (Y direction) of the polarizing element 1, the pitch P in the transmission axis direction (X direction) of the ridges 22 is It must be shorter than the wavelength of light in the band. The reason for this is to obtain the polarizing action mentioned above. More specifically, the pitch P of the ridges 22 is preferably 50 to 300 nm, more preferably 100 to 200 nm, from the viewpoint of achieving both ease of manufacture of the ridges 22 and polarization characteristics. It is preferably between 100 and 150 nm, particularly preferably between 100 and 150 nm.

Further, as shown in FIGS. 1 and 2, the width W _B of the bottom portion of the ridge portion 22 in the longitudinal section (XZ section) is not particularly limited. It is preferably about 10 to 150 nm, more preferably about 10 to 100 nm. Further, the width W _T of the top portion of the ridge 22 is not particularly limited, but from the viewpoint of compatibility between manufacturing easiness and polarization characteristics, it is preferably about 5 to 60 nm, more preferably about 10 to 30 nm. more preferred.

The width _WB of the bottom portion and the width _WT of the top portion of the ridge portion 22 can be measured by observation with a scanning electron microscope or a transmission electron microscope. For example, using a scanning electron microscope or a transmission electron microscope, a cross section (XZ cross section) perpendicular to the absorption axis direction or the reflection axis direction of the polarizing element 1 is observed, and any four ridge portions 22 are observed. Measure the width of the ridge 22 at a height position above 20% of the height H of the ridge 22 from the bottom of the ridge 22, and take the arithmetic mean value of these values as the width _WB of the bottom of the ridge 22. be able to. In addition, the width of the projected streak portion 22 at a height position 20% below the height H of the projected streak portion 22 from the tip 22a of the projected streak portion 22 at any of the four locations is measured. can be taken as the width W _T of the top of the ridge 22 .

In addition, as shown in FIG. 1, the height H of the ridges 22 in the longitudinal section (XZ section) is not particularly limited, but from the viewpoint of both ease of manufacture and polarization characteristics, it is about 50 to 350 nm. It is preferably about 100 to 300 nm, more preferably about 100 to 300 nm. The height H of the ridges 22 can be measured by observation with a scanning electron microscope or a transmission electron microscope. For example, using a scanning electron microscope or a transmission electron microscope, a cross section perpendicular to the absorption axis direction or the reflection axis direction of the polarizing element 1 is observed, and the width It is possible to measure the height of the protruding portion 22 at the center position of the direction, and take the arithmetic average value thereof as the height H of the protruding portion 22 .

The shape of the ridges 22 of the grid structure 20 is preferably tapered in order to obtain good polarization splitting characteristics for obliquely incident light. Here, the tapered shape is a shape in which the width W of the ridge 22 (the width in the X direction in the XZ cross section) gradually narrows as the distance from the base 21 increases, in other words, the bottom of the ridge 22 The width W of the ridge portion 22 is gradually narrowed from the top to the top. Therefore, when the protruding portion 22 has a tapered shape, the width W _T of the top portion of the protruding portion 22 is smaller than the width W _B of the bottom portion of the protruding portion 22 (W _T <W _B ).

FIG. 3 shows a specific example of the tapered shape of the protruding portion 22 according to this embodiment. As shown in FIG. 3, if the cross-sectional shape of the ridge portion 22 in the vertical cross section (XZ cross section) is tapered, the width W becomes narrower as the distance from the base portion 21 increases. It may be of various shapes such as oval or rounded wedge. For example, the cross-sectional shape of the ridge portion 22A shown in FIG. The cross-sectional shape of 22D is wedge-shaped with rounded tops and bottoms. In this way, the tapered shape of the ridges 22 makes it easier to form the reflective film 30 that covers the tip 22a and part of the side surfaces 22b of the ridges 22, thereby imparting polarization characteristics to the polarizing element 1. Since the tapered shape can also be formed by nanoimprinting, it is also advantageous in terms of ease of manufacture.

Moreover, the refractive index of the grid structure 20 gradually changes because the protruding portion 22 has a tapered shape such as a tapered shape. Therefore, similar to the moth-eye structure, the physical refractive index change of the grid structure 20 provides the effect of preventing reflection of incident light. Therefore, the effect that the reflectance on the surface of the protruding portion 22 of the grid structure 20 can be reduced and the transmittance of the grid structure 20 can be improved can also be expected.

Also, FIG. 4 shows a specific example of the shape of the recess 24 formed between the protruding streaks 22, 22 adjacent to each other. The recessed portion 24 is a groove extending in the longitudinal direction (Y direction) of the protruding portion 22 . As shown in FIG. 4, the cross-sectional shape of the concave portion 24 in the vertical cross section (XZ cross section) may have various shapes as long as the width becomes narrower toward the bottom of the concave portion 24 . For example, the cross-sectional shape of the recess 24A shown in FIG. 4 is trapezoidal (tapered), the cross-sectional shape of the recess 24B is triangular (V-shaped), and the cross-sectional shape of the recess 24C is substantially rectangular with a flat bottom. The cross-sectional shape of the recess 24D is U-shaped with a rounded bottom. As for the shape of these concave portions 24, an optimum shape can be appropriately selected in consideration of productivity such as releasability at the time of nanoimprint formation.

Moreover, the material constituting the grid structure 20 is not particularly limited as long as it is a transparent organic material, and a known organic material can be used. For example, it is preferable to use various thermosetting resins, various ultraviolet curable resins, and the like as the material of the grid structure 20 in terms of ensuring transparency and being excellent in manufacturability.

Furthermore, it is preferable to use a material different from that of the substrate 10 for the material constituting the grid structure 20 in terms of ease of manufacture and manufacturing cost. In addition, if the materials of the grid structure 20 and the substrate 10 are different, the refractive indices of both will be different. Therefore, if the refractive index of the entire polarizing element 1 is affected, a refractive index adjusting layer may be appropriately provided between the grid structure 20 and the substrate 10 .

For example, as a material for forming the grid structure 20, a curable resin such as an epoxy polymerizable compound or an acrylic polymerizable compound can be used. Epoxy polymerizable compounds are monomers, oligomers, or prepolymers having one or more epoxy groups in the molecule. Examples of epoxy polymerizable compounds include various bisphenol-type epoxy resins (bisphenol A-type, F-type, etc.), novolac-type epoxy resins, various modified epoxy resins such as rubber and urethane, naphthalene-type epoxy resins, biphenyl-type epoxy resins, and phenol novolak-type epoxy resins. Epoxy resins, stilbene-type epoxy resins, triphenolmethane-type epoxy resins, dicyclopentadiene-type epoxy resins, triphenylmethane-type epoxy resins, prepolymers thereof, and the like.

Acrylic polymerizable compounds are monomers, oligomers, or prepolymers having one or more acrylic groups in the molecule. Here, monomers are further classified into monofunctional monomers having one acrylic group in the molecule, bifunctional monomers having two acrylic groups in the molecule, and polyfunctional monomers having three or more acrylic groups in the molecule. .

Examples of the "monofunctional monomer" include carboxylic acids (acrylic acid, etc.), hydroxys (2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate), alkyl or alicyclic monomers (isobutyl acrylate , t-butyl acrylate, isooctyl acrylate, lauryl acrylate, stearyl acrylate, isobornyl acrylate, cyclohexyl acrylate), other functional monomers (2-methoxyethyl acrylate, methoxyethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate , benzyl acrylate, ethyl carbitol acrylate, phenoxyethyl acrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminopropylacrylamide, N,N-dimethylacrylamide, acryloylmorpholine, N-isopropylacrylamide, N,N- diethylacrylamide, 2-(perfluorooctyl)ethyl acrylate, 3-perfluorohexyl-2-hydroxypropyl acrylate, 3-perfluorooctyl-2-hydroxypropyl-acrylate, 2-(perfluorodecyl)ethyl-acrylate, 2 -(perfluoro-3-methylbutyl)ethyl acrylate), 2,4,6-tribromophenol acrylate, 2,4,6-tribromophenol methacrylate, 2-(2,4,6-tribromophenoxy)ethyl acrylate ), 2-ethylhexyl acrylate and the like.

Examples of "bifunctional monomers" include tri(propylene glycol) diacrylate, trimethylolpropane-diallyl ether, urethane diacrylate and the like.
"Multifunctional monomers" include, for example, trimethylolpropane triacrylate, dipentaerythritol penta and hexaacrylate, ditrimethylolpropane tetraacrylate, and the like.

Examples other than the acrylic polymerizable compounds listed above include acrylic morpholine, glycerol acrylate, polyether acrylate, N-vinylformamide, N-vinylcaprolactam, ethoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, polyethylene glycol acrylate, EO-modified trimethylolpropane triacrylate, EO-modified bisphenol A diacrylate, aliphatic urethane oligomers, polyester oligomers, and the like.

Moreover, examples of the curing initiator for the above-described curable resin include a heat curing initiator, a photocuring initiator, and the like. The curing initiator may be one that is cured by heat, energy rays other than light (for example, electron beams), or the like. When the curing initiator is a thermosetting initiator, the curable resin is a thermosetting resin, and when the curing initiator is a photo-setting initiator, the curable resin is a photo-setting resin.

Among these, it is preferable to use an ultraviolet curing initiator as the curing initiator. An ultraviolet curing initiator is a kind of photocuring initiator. UV curing initiators include, for example, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexylphenylketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one etc. Therefore, the curable resin is preferably an ultraviolet curable resin. Moreover, from the viewpoint of transparency, the curable resin is more preferably an ultraviolet curable acrylic resin.

In addition, the method of forming the grid structure 20 is not particularly limited as long as it is a method capable of forming the base portion 21 and the ridge portion 22 described above. For example, an unevenness forming method using photolithography, imprinting, or the like can be used. Among these, imprinting is used to form the base portion 21 and the ridge portions 22 of the grid structure 20 from the standpoint of being able to form the concave-convex pattern easily in a short period of time and to reliably form the base portion 21 . is preferred.

When forming the base portion 21 and the ridges 22 of the grid structure 20 by nanoimprinting, for example, a material for forming the grid structure 20 (grid structure material) is applied on the substrate 10, and then unevenness is formed. The original plate on which is formed is pressed against the grid structure material, and in this state, the grid structure material can be cured by irradiating ultraviolet rays or applying heat. Thereby, the grid structure 20 having the base portion 21 and the ridge portion 22 can be formed.

<2.3. Reflective Film (Functional Film)>
The polarizing element 1 according to this embodiment includes a reflective film 30 formed on the ridges 22 of the grid structure 20, as shown in FIGS.

As shown in FIG. 1 , the reflective film 30 is formed so as to partially cover the tips 22 a and side surfaces 22 b of the ridges 22 of the grid structure 20 . Then, as shown in FIG. 1 , the reflective film 30 is formed to extend along the longitudinal direction (Y direction) of the ridges 22 of the grid structure 20 . As a result, the reflective film 30 can reflect light having an electric field component in a direction (reflection axis direction: Y direction) parallel to the longitudinal direction of the ridges 22 among the light incident on the polarizing element 1 .

The material forming the reflective film 30 is not particularly limited as long as it is a material that reflects light in the working band. Examples thereof include metal elements such as Al, Ag, Cu, Mo, Cr, Ti, Ni, W, Fe, Si, Ge, and Te, and metal materials such as alloys containing one or more of these elements.

Note that the reflective film 30 may be a single-layer film made of the above metal, or may be a multi-layer film made of a plurality of metal films. In addition, the reflective film 30 may include other layers such as dielectric films as necessary, as long as it has a reflective function. A dielectric film is a thin film made of a dielectric. General materials such as SiO ₂ , Al ₂ O ₃ , MgF ₂ and TiO ₂ can be used as materials for the dielectric film. Also, the refractive index of the dielectric film is preferably greater than 1.0 and equal to or less than 2.5. Since the optical properties of the reflective film 30 are also affected by the surrounding refractive index, the polarization properties may be controlled by the material of the dielectric film.

<2.4. Special shape of ridge and reflective film>
Here, the special shapes of the ridges 22 of the grid structure 20 and the reflective film 30 in the polarizing element 1 according to this embodiment will be described in detail.

In the polarizing element 1 according to the present embodiment, as shown in FIGS. 1 and 5, the reflective film 30 covers the tip 22a of the ridge 22 of the grid structure 20 and the upper part of at least one side surface 22b, Moreover, it is formed so as not to cover the lower side of both side surfaces 22b of the protruding portion 22 and the base portion 21 . In the example of FIGS. 1 and 5, the reflective film 30 covers the upper side of both side surfaces 22b of the protruding portion 22, but covers the upper portion of only one side surface 22b of the protruding portion 22. good too.

Here, "the state in which the reflective film 30 covers the tip 22a and the upper side of at least one of the side surfaces 22b of the ridges 22 of the grid structure 20" means, for example, as shown in FIGS. Both the tip 22a of the ridge portion 22 and the upper side of the side surface 22b connecting the tip 22a of the ridge portion 22 and the base portion 21 are continuously covered with the reflective film 30, while the side surface 22b and the base portion 21 are not covered with the reflective film 30 and are exposed. In this state, the reflective film 30 does not cover the entire side surface 22b of the protruding portion 22 (all side surfaces 22b from the tip 22a of the protruding portion 22 to the base portion 21).

Furthermore, the surface of the reflective film 30 covering the tip 22a of the ridge 22 and the upper side of at least one side surface 22b (hereinafter sometimes referred to as the "top of the ridge 22") is rounded. It has a curved shape (for example, a vertically elongated substantially elliptical shape), and bulges in the width direction (X direction) of the protruding portion 22 . In this way, the surface of the reflective film 30 has a rounded, smoothly curved shape, and does not have sharp corners or steps. The maximum width W _MAX of the reflective film 30 covering the top of the ridge 22 is equal to or greater than the width _WB of the bottom of the ridge 22 . Further, W _MAX is preferably greater than _WB .

Here, the maximum width W _MAX of the reflective film 30 covering the ridge 22 is the largest horizontal width of the outermost surfaces on both sides of the reflective film 30 in the width direction (X direction) of the ridge 22. Horizontal width. As shown in FIGS. 1 and 5, the horizontal width (width in the X direction) of the outermost surfaces on both sides of the reflective film 30 covering the ridge 22 corresponds to the height position of the reflective film 30 (width in the Z direction). height), the maximum of these horizontal widths is the maximum width W _MAX . In other words, the maximum width W _MAX is the maximum value of the total width of the thickness Ds×2 on both sides of the reflective film 30 and the horizontal width W of the ridge 22 . For example, when light enters the grid structure 20 from the front direction (Z direction) (when the incident angle θ=0°), W _MAX corresponds to the effective grid width of the reflective film 30 .

As shown in FIGS. 1 and 3, the width W _B of the bottom portion of the ridge portion 22 is 20% above the height H of the ridge portion 22 from the bottom of the ridge portion 22 (upper surface of the base portion 21). It is the horizontal width (width in the X direction) of the protruding portion 22 at the height position (height in the Z direction). That is, the width W _B of the bottom portion of the ridge portion 22 is the horizontal width of the ridge portion 22 at a height of 0.2×H above the upper surface of the base portion 21 .

Further, as shown in FIGS. 1 and 3, the width W _T of the top portion of the ridge portion 22 is the height position (Z is the horizontal width (width in the X direction) of the protruding portion 22 in the height in the X direction). That is, the width W _T of the top portion of the protruding portion 22 is 0.8×H above the upper surface of the base portion 21 (that is, 0.2×H below the tip 22a of the protruding portion 22). height position)).

In the following description, the convex structure formed by combining the ridges 22 and the reflective film 30 is referred to as a "grid", and the height of the convex structure (that is, the grid) formed by combining the ridges 22 and the reflective film 30 is is sometimes referred to as "grid height". Further, the maximum width W _MAX of the reflective film 30 covering the ridges 22 may be referred to as the "grid maximum width W _MAX ", and the width W _B of the bottom of the ridges 22 may be referred to as the "grid bottom width _WB ". be. Further, the width W _T of the top portion of the protruding portion 22 may be referred to as the “protrusive portion top width W _T ”, and the width at the central position in the height direction of the protruding portion 22 may be referred to as the “protruding portion central width”. be.

Thus, in this embodiment, as the width W _B of the bottom portion of the ridge portion 22, the horizontal width of the ridge portion 22 at a height position 20% above the lowest portion (bottom portion) of the ridge portion 22 is used. As the width W _T of the top portion of the ridge portion 22, the horizontal width of the ridge portion 22 at a height position 20% lower than the tip 22a of the ridge portion 22 is used. The reason for this is that the width of the lowermost portion of the ridge portion 22 on the upper surface of the base portion 21 and the width of the tip 22a of the ridge portion 22 vary greatly depending on the manufacturing conditions of the grid structure 20, and these widths must be precisely adjusted. This is because it is difficult to measure

As described above, in the grid structure 20 according to the present embodiment, the tapered ridges 22 and the reflective film 30 covering only the tip 22a and the upper side of the side surface 22b of the ridges 22 are formed. It is The lower side of the side surface 22b of the ridge 22 is not covered with the reflective film 30 and is open.

As a result, the cross-sectional shape of the ridges 22 covered with the curved reflective film 30 (that is, the cross-sectional shape of the grid) has the following special cross-sectional shape. That is, as shown in FIGS. 1 and 5, etc., the horizontal width (for example, the maximum grid width W _MAX ) of the upper portion of the ridge 22 where the reflective film 30 is present is large, and the reflective film 30 is not covered. The horizontal width (for example, the width W _B of the exposed bottom portion of the exposed ridge 22) from the center to the bottom side of the ridge 22 exposed is small. The cross-sectional shape of the entire convex structure (that is, the “grid”) composed of the ridges 22 and the reflective film 30 is constricted inward at a position directly below the lower end of the curved reflective film 30 . , has a narrowed width in the X direction. The special cross-sectional shape of such a grid can be likened to the shape of a tree. Specifically, the leaf portion of the tree that spreads round and wide corresponds to the portion of the reflective film 30 that covers the top of the ridge portion 22 , and the trunk portion of the tree is the convex portion that is not covered with the reflective film 30 . The base portion 21 corresponds to the lower portion of the streak portion 22 and the portion of the ground where the tree grows. Therefore, in the following description, the special cross-sectional shape of the grid composed of the ridges 22 of the grid structure 20 and the reflective film 30 as described above is referred to as a "special tree shape".

The grid of the grid structure 20 of the polarizing element 1 according to this embodiment has a special tree shape as described above. As a result, for example, as shown in FIG. 31, which will be described later, when incident light enters the polarizing element 1 from an oblique direction, the effective grid width _WA becomes small and the gap width _WG becomes large. Here, the effective grid width _WA is the width of the reflective film 30 in the direction perpendicular to the obliquely incident light. The gap width _WG is the width of the gap between the reflective films 30, 30 of two adjacent grids in the direction perpendicular to the obliquely incident light. _As the effective grid width WA increases, obliquely incident light is more likely to be reflected by the reflective film 30 and less likely to reach the transparent ridges 22 and base 21 . Therefore, the transmittance of obliquely incident light in the polarizing element 1 is lowered. On the other hand, the larger the gap width _WG , the easier it is for the obliquely incident light to pass through between the two adjacent reflecting films 30 and reach the transparent ridge 22 and base 21 . Therefore, the transmittance for obliquely incident light can be increased.

Therefore, since the grid of the polarizing element 1 according to this embodiment has the above-mentioned special tree shape, the gap width _WG with respect to the obliquely incident light is increased, and the obliquely incident light passes through the round gaps between the reflecting films 30, 30. , to easily reach and pass through the transparent grid structure 20 . Therefore, since the transmission axis transmittance Tp of the obliquely incident light is high, the transmittance of the obliquely incident light and the polarization separation characteristic (Tp×Rs characteristic) are very excellent. Furthermore, the function of reflecting obliquely incident light by the reflective film 30 and the function of transmitting obliquely incident light by the grid structure 20 can be achieved in a well-balanced manner, and the polarization splitting characteristics for obliquely incident light can be further improved.

<2.5. Formation method and specific examples of reflective film>
Here, a method for forming the reflective film 30 will be described with reference to FIG.

As a method of forming the reflective film 30 so that the reflective film 30 covers the tips 22a and part of the side surfaces 22b of the ridges 22 of the grid structure 20, as shown in FIG. It is preferable to form the reflective film 30 by performing sputtering or vapor deposition alternately from an oblique direction (film formation incident angle φ) with respect to the ridges 22 . As a result, the reflective film 30 can be formed so as to cover the tip 22a and the upper side of the side surfaces 22b of the protruding portion 22. As shown in FIG. The film formation incident angle φ for forming the reflective film 30 by sputtering or vapor deposition is not particularly limited, but can be, for example, about 5 to 70° with respect to the surface of the substrate 10 .

Thus, in this embodiment, after forming the grid structure 20 made of a transparent material, the reflective film 30 made of a metal material is formed by sputtering or vapor deposition. This makes it possible to easily change the film formation conditions, material, and film thickness of the reflective film 30 . Moreover, even when the reflective film 30 is composed of a multilayer film, it can be easily dealt with. Therefore, by combining metals, semiconductors, and dielectrics, it is possible to design a film that utilizes the interference effect, and there is no need to consider the composition of materials that can be etched when forming the reflective film 30 by etching as in the conventional technology. . Thereby, it becomes easy to adjust the reflectance of the polarized wave parallel to the grid structure 20 and the transmittance (the amount of transmission) of the polarized light in the direction perpendicular to the grid. In addition, since the reflective film 30 is formed after the grid structure 20 is formed, equipment such as a vacuum dry etching device is not required, and gas and abatement devices suitable for complicated processes and etching materials can be used. There is no need for any safety equipment. Therefore, running costs such as equipment investment and maintenance can be reduced, and cost merits can also be obtained.

The thickness Dt of the reflective film 30 covering the tip 22a of the ridge 22 shown in FIG. 5 and the thickness Ds of the reflective film 30 covering the side surface 22b of the ridge 22 are not particularly limited. It can be changed as appropriate according to the shape of the ridges 22 of 20 and the performance required of the reflective film 30 . For example, from the viewpoint of obtaining better reflection performance, the thicknesses Dt and Ds of the reflective film 30 are preferably 2 to 200 nm, more preferably 5 to 150 nm, and even more preferably 10 to 100 nm. It is preferably 15 to 80 nm, and particularly preferably 15 to 80 nm. The thickness Ds of the reflective film 30 is the thickness of the thickest portion of the reflective film 30 covering the side surface 22b of the ridge 22, as shown in FIG.

In addition, the shape of the reflective film 30 is not particularly limited as long as it is a shape capable of forming the special tree shape described above. can be selected as appropriate.

FIG. 6 is a cross-sectional view schematically showing a specific example of the shape of the reflective film 30. As shown in FIG. As shown in FIG. 6, the reflective film 30 may have various shapes as long as the reflective film 30 is curved so as to wrap around the top of the ridge 22 (upper side of the tip 22a and the side surface 22b).

For example, the reflective film 30A shown in FIG. 6 covers the apexes of the ridges 22A, 22B, and 22C having various cross-sectional shapes so as to envelop the tops of the ridges 22A, 22B, and 22C. It has an oval shape. In addition, the reflective film 30B has a curved shape that wraps and covers the top of the substantially wedge-shaped ridge 22D. In addition, the reflective film 30C has a curved shape that wraps around the apex of the trapezoidal projection 22A. The coverage Rc of one side surface 22b of the protruding portion 22 and the coverage Rc of the other side surface 22b of the ridge portion 22 by the reflective films 30B and 30C are substantially the same.

In addition, the reflective film 30D covers the apex of the substantially wedge-shaped ridge 22D so as to enclose it, but is unevenly distributed on one side surface 22b (left side surface 22b shown in FIG. 6) of the ridge 22. . Specifically, the reflective film 30D covers a wide range of the left side surface 22b of the ridge 22, and the coverage Rc is about 80%. On the other hand, the reflective film 30D covers only a narrow upper portion of the right side surface 22b, and its coverage Rc is about 25%. In this manner, the coverage Rc of the reflecting film 30D may differ between the one side surface 22b and the other side surface 22b of the protruding portion 22. FIG.

<2.6. Preferred Range of Coverage Rc of Protrusions with Reflective Film>
Next, a preferable range of the coverage Rc of the side surface 22b of the protruding portion 22 by the reflective film 30 according to the present embodiment will be described.

The coverage Rc is preferably 25% or more and 80% or less. Here, the coverage Rc is the height (Hx) of the portion of the side surface 22b of the protruding portion 22 covered with the reflective film 30 with respect to the height (H) of the protruding portion 22 shown in FIGS. is the ratio of The coverage Rc is represented by the following formula (1).

Rc [%] = (Hx/H) x 100 (1)
H: Height in the Z direction of the ridge 22 Hx: Height in the Z direction of the portion of the side surface 22b of the ridge 22 covered with the reflective film 30

Further, the openness ratio Rr is the height (H− Hx). The open rate Rr is represented by the following formula (2).

Rr [%]=((H−Hx)/H)×100 (2)

From the above definition, Rr=100-Rc. Therefore, when the coverage Rc of the side surface 22b of the ridge portion 22 by the reflective film 30 is 25% or more and 80% or less, the opening ratio Rr of the side surface 22b of the ridge portion 22 by the reflective film 30 is 20% or more. , 75% or less.

As described above, in the polarizing element 1 according to the present embodiment, the coverage Rc of the side surface 22b of the ridge 22 by the reflective film 30 is 25% or more and 80% or less (that is, the openness Rr is 20% or more and 75% or less). % or less). Specifically, in this embodiment, the reflective film 30 is formed so as to cover the tip 22a and the upper side of both side surfaces 22b of the protruding portion 22 and leave the lower side of the side surface 22b open without covering. . The coverage Rc is preferably 25% or more and 80% or less, more preferably 30% or more and 70% or less, and even more preferably 40% or more and 50% or less.

With such a configuration, the polarizing element 1 according to the present embodiment can exhibit sufficient transmittance even for obliquely incident light with a large incident angle θ (for example, 45 to 60°). For example, when the polarizing element 1 separates obliquely incident light into S-polarized light (reflected light) and P-polarized light (transmitted light), the P-polarized light (transmitted light) transmitted through the polarizing element 1 is ) can be maintained at a high value. In addition, by setting the coverage Rc to 25% or more and 80% or less, the contrast (CR = Tp/Ts), which is the ratio of the transmission axis transmittance (Tp) to the transmission axis reflectance (Ts), can be maintained at a good level. While maintaining the above, the reflecting action of the reflecting film 30 described above can be exhibited more reliably without depending on the incident angle θ. Therefore, regardless of the incident angle θ of the obliquely incident light, it is possible to ensure high transmittance of transmitted light and improve the polarization splitting characteristics.

On the other hand, as a comparative example, the reflective film 30 is formed so as to cover only the tips 22a of the ridges 22 of the grid structure 20, or the reflective film 30 is formed to cover only the tips 22a of the ridges 22 and the entire side surface 22b on one side. (See, for example, FIG. 18.), the transmittance Tp varies greatly depending on the incident angle θ of the oblique incident light. It is considered that sufficient permeability cannot be obtained. Further, as a comparative example, when the reflective film 30 covers all of the tips 22a and both side surfaces 22b of the ridges 22 of the grid structure 20 (when the coverage Rc is 100%), the oblique incident light As the angle of incidence θ increases, the transmittance decreases significantly.

Therefore, from the viewpoint of improving the transmittance of transmitted light and the polarization separation characteristics without depending on the incident angle θ of the obliquely incident light, the reflective film 30 can be used as the reflective film 30 as in the polarizing element 1 according to the present embodiment. It is preferable to cover the tip 22a of 22 and a portion of at least one side surface 22b (upper side of the side surface 22b).

Furthermore, from the viewpoint of the Tp×Rs characteristics required for a polarizing beam splitter (PBS), in the polarizing element 1 according to the present embodiment, the coverage Rc of the side surface 22b of the protruded portion 22 with the reflective film 30 is 25% or more. , 80% or less (for example, see FIG. 27).

If the coverage Rc is less than 25%, the transmission axis transmittance Tp of the P-polarized light that passes through the polarizing element 1 is reduced, and the transmittance Tp varies depending on the incident angle θ. The value of xRs is also not obtained. For this reason, it is not possible to obtain sufficient transmittance of transmitted light and polarization separation characteristics represented by Tp×Rs for obliquely incident light with a large incident angle θ. On the other hand, when the coverage Rc is more than 80% (see, for example, FIG. 20), the oblique incident light As the incident angle .theta. increases (for example, 45 to 60.degree.), the transmission axis transmittance Tp decreases, so that the transmittance Tp varies greatly depending on the incident angle .theta.

Therefore, the coverage Rc of the side surface 22b of the protruding portion 22 with the reflective film 30 is preferably 25% or more and 80% or less (see FIG. 27, for example). As a result, when light is obliquely incident on the polarizing element 1 at an incident angle θ of 45°, for example, the transmission axis transmittance Tp of the second polarized light (P-polarized light) passing through the polarizing element 1 is set to 75°. % or higher. As a result, Tp×Rs can be made 70% or more. Therefore, even when a wide range of obliquely incident light is incident at a large incident angle θ, the transparency of the second polarized light (P-polarized light) in the transmission axis direction of the polarizing element 1 is increased, and the polarization separation characteristics of the polarizing element 1 are improved. The polarizing element 1 can suitably separate the obliquely incident light into the first polarized light (S-polarized light) and the second polarized light (P-polarized light).

From the same point of view, the coverage Rc is more preferably 30% or more and 70% or less (that is, the open rate Rr is 30% or more and 70% or less). As a result, a high transmittance Tp of 80% or more can be obtained, and a high Tp×Rs of 72% or more can be obtained under the oblique incidence condition. More preferably, the coverage Rc is 30% or more and 60% or less (that is, the open rate Rr is 40% or more and 70% or less). As a result, a high transmittance Tp of 83% or more can be obtained, and a high Tp×Rs of 75% or more can be obtained under the oblique incidence condition. Furthermore, it is even more preferable that the coverage Rc is 40% or more and 50% or less (that is, the open rate Rr is 50% or more and 60% or less). As a result, a very high transmittance Tp of 85% or more can be obtained and a very high Tp×Rs of 77% or more can be obtained under the oblique incidence condition.

Further, regarding the reflection axis reflectance Rs, it is preferable that the coverage Rc is 20% or more. As a result, a high reflectance Rs of 85% or more can be obtained under the above oblique incidence condition.

As for the transmitted light contrast CR (CR=Tp/Ts), a sufficient contrast CR can be obtained if the coverage Rc is 20% or more. The higher the coverage Rc, the higher the contrast CR obtained.

<2.7. Preferred Range of Tp×Rs>
Next, a suitable range of “Tp×Rs”, which is an index representing the polarization splitting characteristics of the wire grid polarizing element 1 according to this embodiment, will be described.

Tp×Rs [%] represents the product of transmission axis transmittance (Tp) and reflection axis reflectance (Rs) in percentage. This Tp×Rs is an index representing the polarization separation characteristics of the wire grid polarization element 1 .
Tp x Rs [%] = (Tp [%]/100) x (Rs [%]/100) x 100

As described above, the transmission axis transmittance (Tp) is the transmittance of the second polarized light (P polarized light) having an electric field component parallel to the transmission axis (X direction) of the polarizing element 1 . The reflection axis reflectance (Rs) is the reflectance of the first polarized light (S polarized light) having an electric field component parallel to the reflection axis (Y direction) of the polarizer 1 .

When the wire grid polarizing element 1 according to the present embodiment is used as a polarizing beam splitter to separate incident light into S-polarized light and P-polarized light (see FIGS. 15 to 17), the polarizing element 1 is used as a polarizing beam splitter. It is arranged at a predetermined angle (for example, 45°) with respect to the light. For example, when incident light from a light source enters the polarizing element 1 at an incident angle θ of about 45°, the incident light is converted by the polarizing element 1 into first polarized light (S polarized light: reflected light) and second polarized light. polarized light (P-polarized light: transmitted light). S-polarized light is light having an electric field component in a direction parallel to the longitudinal direction of the ridges 22 of the grid structure 20 (reflection axis direction shown in FIG. 2: Y direction) in the incident light. On the other hand, P-polarized light is light having an electric field component in a direction parallel to the width direction of the ridges 22 of the grid structure 20 (transmission axis direction shown in FIG. 2: X direction) in the incident light.

The S-polarized light in the reflection axis direction mainly becomes reflected light reflected by the reflection film 30 of the polarizing element 1 . The reflectance [%] of S-polarized light at this time is the reflection axis reflectance (Rs). The reflection axis reflectance (Rs) represents the ratio of S-polarized light reflected by the polarizing element 1 to the S-polarized light incident on the polarizing element 1 . The reflection axis transmittance (Rp) represents the ratio of S-polarized light that passes through the polarizing element 1 to the S-polarized light incident on the polarizing element 1 .

On the other hand, the P-polarized light in the transmission axis direction mainly becomes transmitted light that passes through the transparent grid structure 20 and the substrate 10 of the polarizing element 1 . The transmittance [%] of the P-polarized light at this time is the transmission axis transmittance (Tp). The transmission axis transmittance (Tp) represents the ratio of P-polarized light that is transmitted through the polarizing element 1 to the P-polarized light incident on the polarizing element 1 . The transmission axis reflectance (Ts) represents the ratio of the P-polarized light reflected by the polarizing element 1 to the P-polarized light incident on the polarizing element 1 .

Therefore, a higher transmission axis transmittance Tp means that P-polarized light in the transmission axis direction can be efficiently transmitted. Also, the higher the reflection axis reflectance Rs, the more efficiently the S-polarized light in the reflection axis direction can be reflected. Therefore, the higher the Tp × Rs value, which is the product of Tp and Rs, the higher the transmittance of P-polarized light (transmitted light) and the reflectivity of S-polarized light (reflected light), and the polarization separation characteristics as a polarizing beam splitter. be superior to

Here, a preferable range of the value of Tp×Rs according to this embodiment will be described. Light with a wavelength in a predetermined range (eg, 430 to 680 nm) is incident on the polarizing element 1 according to the present embodiment from an oblique direction at a predetermined incident angle θ (eg, 45°), and P-polarized light (transmitted light) Consider the case of separating into S-polarized light (reflected light). Under such oblique incidence conditions, Tp×Rs is preferably 70% or more from the viewpoint of good polarization splitting characteristics of the polarizing element 1 .

When Tp×Rs is less than 70%, the display device to which the polarizing element is applied has poor light utilization efficiency, insufficient brightness of the displayed image, and poor visibility. On the other hand, if Tp×Rs is 70% or more, it is possible to increase the efficiency of light utilization in the display device to which the polarizing element 1 is applied, ensure sufficient brightness of the displayed image, and improve the visibility.

Furthermore, Tp×Rs is more preferably 72% or more, even more preferably 75% or more, and particularly preferably 80% or more. As a result, it is possible to further improve the utilization efficiency of light and the brightness and visibility of the displayed image as described above.

<2.8. Preferred Range of Height H of Protruding Streak>
When incident light is incident on the polarizing element 1 according to the present embodiment at a relatively large incident angle θ (for example, 45°), the height H of the ridges 22 of the grid structure 20 (Figs. 3, etc.) is preferably 160 nm or more, more preferably 180 nm or more, and particularly preferably 220 nm or more (see FIG. 24). As a result, high transmission axis transmittance Tp, excellent Tp×Rs characteristics, and high contrast CR of transmitted light can be obtained.

Specifically, regarding the transmittance, if the height H of the ridges 22 is 160 nm or more, the transmission axis transmittance Tp of obliquely incident light becomes 80% or more, and high transmittance is obtained. Furthermore, if H is 180 nm or more, Tp of 85% or more can be obtained, which is more preferable. In addition, if H is 220 nm or more, Tp of 87% or more can be obtained, which is particularly preferable.

As for the Tp×Rs characteristics required for a polarizing beam splitter (PBS), if the height H of the ridges 22 is 160 nm or more, an excellent Tp×Rs of 70% or more can be obtained. Furthermore, if H is 180 nm or more, Tp×Rs of 75% or more can be obtained, which is more preferable. In addition, if H is 220 nm or more, Tp×Rs of 77% or more can be obtained, which is particularly preferable.

Regarding the contrast CR (CR=Tp/Ts) of transmitted light, the height H of the ridges 22 should be 100 nm or more. can get. Furthermore, if H is 180 nm or more, an excellent CR of 250 or more can be obtained, which is more preferable. In addition, if H is 220 nm or more, an excellent CR of 500 or more can be obtained, which is particularly preferred.

As described above, in order to improve various characteristics (Tp, Tp×Rs, CR) of the polarizing element 1, particularly Tp, it is preferable that the height H of the ridges 22 is larger. . The reason for this is considered as follows. That is, when the film formation incident angle φ (see FIG. 5) is the same when the reflective film 30 is formed on the ridges 22 by sputtering, vapor deposition, or the like, the lower the height H of the ridges 22, the lower the angle. , the coverage Rc of the reflective film 30 increases. As the coverage Rc increases, the range of the ridges 22 covered by the reflective film 30 increases, making it difficult for P-polarized light to pass through the grid structure 20, and the transmittance Tp decreases. Therefore, under the condition that the film formation incident angle φ is the same, it is preferable to decrease the coverage Rc and increase the transmittance Tp by increasing the height H of the ridges 22. .

<2.9. Preferred Range of Tip Thickness Dt of Functional Film (Reflective Film)>
When incident light is incident on the polarizing element 1 according to the present embodiment at a relatively large incident angle θ (for example, 45°), the reflection film 30 covering the tips 22a of the ridges 22 of the grid structure 20 is The thickness Dt (tip thickness Dt of the reflective film 30: see FIG. 5) is preferably 5 nm or more, more preferably 15 nm or more (for example, see FIG. 25).

If the tip thickness Dt of the reflective film 30 is 5 nm or more, both the reflection axis reflectance Rs and the transmission axis transmittance Tp of obliquely incident light are 85% or more, and high transmittance is obtained. Furthermore, considering the Tp characteristics and the Tp×Rs characteristics required for a polarizing beam splitter, Dt is more preferably 15 nm or more.

<2.10. Preferred Range of Side Thickness Ds of Functional Film (Reflective Film)>
Moreover, the thickness Ds of the reflective film 30 covering the side surfaces 22b of the ridges 22 of the grid structure 20 (the side surface thickness Ds of the reflective film 30: see FIG. 5) is preferably 10 nm or more and 30 nm or less. , 12.5 nm or more and 25 nm or less, and particularly preferably 15 nm or more and 25 nm or less (see FIG. 26, for example). As a result, high transmission axis transmittance Tp, excellent Tp×Rs characteristics, and high contrast CR of transmitted light can be obtained.

Specifically, regarding the transmittance, if the side thickness Ds of the reflective film 30 is 10 nm or more and 30 nm or less, the transmission axis transmittance Tp of the obliquely incident light becomes 80% or more, and a high transmittance is obtained. . Furthermore, if Ds is 12.5 nm or more and 25 nm or less, Tp of 85% or more can be obtained, which is more preferable.

As for the reflectance, if the side thickness Ds of the reflecting film 30 is 10 nm or more, the reflection axis reflectance Rs of the obliquely incident light becomes 80% or more, and a high reflectance is obtained. Furthermore, if Ds is 12.5 nm or more, Rs of 85% or more can be obtained, which is more preferable.

Regarding the Tp×Rs characteristics required for a polarizing beam splitter (PBS), if the side thickness Ds of the reflective film 30 is 12.5 nm or more and 30 nm or less, an excellent Tp×Rs of 70% or more can be obtained. be done. Furthermore, if Ds is 15 nm or more and 25 nm or less, Tp×Rs of 76% or more can be obtained, which is more preferable.

Regarding the contrast CR (CR=Tp/Ts) of transmitted light, the side thickness Ds of the reflective film 30 should be 10 nm or more, but if Ds is 12.5 nm or more, an excellent contrast of 50 or more is obtained. A CR is obtained. Furthermore, if the Ds is 15 nm or more, a CR of 100 or more can be obtained, which is more preferable.

<2.11. Uneven Distribution of Reflective Film>
In addition, in the polarizing element 1 according to the present embodiment, the reflective film 30 covering the protruding portion 22 is unevenly distributed on one side of the protruding portion 22 so that the shape is left-right asymmetrical in the width direction (X direction) of the protruding portion 22 . (see, for example, FIG. 29). Specifically, the side thickness Ds and the coverage ratio Rc of the reflective film 30 are changed between one side surface 22b and the other side surface 22b of the ridge portion 22, so that the reflective film 30 is formed on the surface of the ridge portion 22. It may be unevenly distributed on one side surface 22b. That is, the reflective film 30 may cover one side surface 22b of the protruding portion 22 thickly and widely, and may cover the other side surface 22b thinly and narrowly.

When the reflective film 30 is unevenly distributed on one side of the ridge portion 22 in this way, the transmission axis transmittance Tp(+) of the incident light with the incident angle +θ (+30° to +60°) to the polarizing element 1 and the incident angle is within 3% of the transmission axis transmittance Tp(-) of incident light at -θ (-30° to -60°). Then, the thickness Ds of the reflective film 30 covering the one side surface 22b and the other side surface 22b of the protruding portion 22, respectively, so that the difference between Tp(+) and Tp(-) is within 3%, It is preferable to adjust the coverage Rc so that the reflective film 30 is appropriately unevenly distributed on one side of the ridge 22 .

The incident angle of +θ means that the obliquely incident light is incident on the ridge 22 from a direction inclined to one side in the X direction (the width direction of the ridge 22). On the other hand, that the incident angle is −θ means that the obliquely incident light is incident on the convex portion 22 from a direction inclined to the other side of the X direction (see FIG. 29, for example).

As described above, when the reflective film 30 is unevenly distributed on one side of the ridge 22, the difference between Tp(+) and Tp(-) is preferably within 3%. As a result, even when the reflective film 30 is unevenly distributed on one side of the ridge 22, high transmission axis transmittance Tp, excellent Tp×Rs characteristics, and high contrast CR of transmitted light can be obtained.

Specifically, regarding the transmittance, even when the reflecting film 30 is unevenly distributed on one side, the transmission axis transmittance Tp of obliquely incident light with incident angles θ of +45° and −45° is 85% or more. , a high transmittance is obtained.

As for the reflectance, even when the reflecting film 30 is unevenly distributed on one side, the reflection axis reflectance Rs of the obliquely incident light with the incident angles θ of +45° and −45° is 85% or more, and the reflection is high. rate is obtained.

Regarding the Tp×Rs characteristics required for a polarizing beam splitter (PBS), even when the reflective film 30 is unevenly distributed on one side, Tp×Rs for obliquely incident light with an incident angle θ of 45° is 75%. As described above, excellent Tp×Rs characteristics are obtained.

Also, with respect to the transmitted light contrast CR (CR=Tp/Ts), an excellent contrast CR can be obtained even when the reflective film 30 is unevenly distributed on one side. Furthermore, from the viewpoint of improving the contrast, among the thicknesses Ds of the reflective film 30 covering the one side surface 22b and the other side surface 22b of the ridge 22, the thickness Ds of the thinner one should be 5 nm or more (its coverage Rc is preferably 22% or more), and it is more preferable that the thickness Ds of the thinner reflective film 30 is 10 nm or more (its coverage Rc is 33% or more).

<2.12. Other Components>
The polarizing element 1 according to this embodiment can further include components other than the substrate 10, the grid structure 20, and the reflective film 30 described above.

For example, as shown in FIG. 7, the polarizing element 1 preferably further includes a protective film 40 formed to cover at least the surface of the reflective film 30 . Specifically, as shown in FIG. 7, the protective film 40 more preferably covers the entire surface of the grid structure 20 . That is, it is more preferable that the protective film 40 is formed so as to cover all of the surface of the base portion 21 and the side surfaces 22b of the ridges 22 of the grid structure 20 and the surface of the reflective film 30 . By forming such a protective film 40, the scratch resistance, antifouling property, and waterproof property of the polarizing element 1 can be further enhanced.

Moreover, it is more preferable that the protective film 40 further includes a water-repellent coating or an oil-repellent coating. As a result, the antifouling property and waterproof property of the polarizing element 1 can be further enhanced.

The material forming the protective film 40 is not particularly limited as long as it can improve the scratch resistance, antifouling property, and waterproof property of the polarizing element 1 . Examples of the material forming the protective film 40 include films made of dielectric materials, and more specifically inorganic oxides, silane-based water-repellent materials, and the like. Examples of inorganic oxides include Si oxides and Hf oxides. The silane-based water-repellent material may contain a fluorine-containing silane compound such as perfluorodecyltriethoxysilane (FDTS), or may contain a non-fluorine-containing silane compound such as octadecyltrichlorosilane (OTS). There may be.

Among these materials, it is more preferable to include at least one of an inorganic oxide and a fluorine-based water-repellent material. By including an inorganic oxide in the protective film 40, the scratch resistance of the polarizing element can be further enhanced, and by including a fluorine-based water-repellent material, the antifouling and waterproofing properties of the polarizing element can be enhanced. can be done.

The protective film 40 may be formed so as to cover at least the surface of the reflective film 30, but as shown in FIG. is more preferred. In this case, for example, the protective film 40 may cover the end surface of the grid structure 20 (the end surface of the base portion 21) as shown in the upper diagram of FIG. 2, the protective film 40 does not have to cover the end surface of the grid structure 20 (the end surface of the base portion 21). Further, as shown in FIG. 8, the protective film 40 may be formed so as to cover the entire polarizing element 1 including the surface of the substrate 10 in addition to the surfaces of the grid structure 20 and the reflective film 30. can. By covering the outermost surface of the grid structure 20 or the polarizing element 1 with the protective film 40 made of an inorganic oxide, the thermal resistance R of the entire polarizing element 1 can be further reduced. is further improved.

Further, the polarizing element 1 according to this embodiment is preferably provided with a heat dissipation member 50 so as to surround the substrate 10 as shown in FIG. The heat radiating member 50 can more efficiently radiate the heat transferred from the substrate 10 . Here, the heat dissipation member 50 is not particularly limited as long as it is a member having a high heat dissipation effect. The heat dissipation member 50 may be, for example, a radiator, heat sink, heat spreader, die pad, heat pipe, metal cover, housing, or the like.

<2.13. Image of actual grid structure>
Next, with reference to FIG. 10, an example in which the polarizing element 1 according to the present embodiment was actually manufactured and photographed enlarged using a scanning electron microscope (SEM) will be described. FIG. 10A is an SEM image of the grid structure 20 before being coated with the reflective film 30, viewed obliquely. 10B is an SEM image showing a cross section of the ridges 22 of the grid structure 20 before being covered with the reflective film 30. FIG. 10C is an SEM image showing a cross section of the ridges 22 of the grid structure 20 covered with the reflective film 30. FIG.

As shown in FIGS. 10A and 10B, the grid structure 20 has a base portion 21 provided along the surface of the substrate 10 and a ridge portion 22 protruding from the base portion 21 . The plurality of ridges 22 are arranged at substantially equal pitches P. As shown in FIG. Each ridge portion 22 has a tapered shape in which the width becomes narrower as the distance from the base portion 21 increases. The width W _T of the top portion of the protruding portion 22 is narrower than the width W _B of the bottom portion of the protruding portion 22 . The pitch P is sufficiently larger than the width W _B of the bottom portion of the protruding portion 22 . The height H of the ridges 22 is greater than the pitch P. In the example of FIG. 10, P=140 nm, W _T =10 nm, W _B =30 nm, H=220 nm. Further, as shown in FIG. 10C, a reflective film 30 is formed so as to cover the tip 22a and both side surfaces 22b of the protruding portion 22. As shown in FIG. The outer surface of the reflective film 30 is rounded and curved, and bulges in the width direction of the ridge 22 .

<3. Manufacturing Method of Polarizing Element>
Next, a method for manufacturing the wire grid polarizing element 1 according to this embodiment will be described with reference to FIG. 11 . 11A to 11D are process diagrams showing a method for manufacturing the wire grid polarizing element 1 according to this embodiment.

As described above, the polarizing element 1 according to this embodiment is a hybrid wire grid polarizing element 1 made of an inorganic material (substrate 10) and an organic material (grid structure 20). A method for manufacturing the hybrid wire grid polarizing element 1 will be described below.

As shown in FIG. 11, the method for manufacturing the wire grid polarizing element 1 according to the present embodiment includes a grid structure material forming step (S10), a nanoimprinting step (S12), a grid structure forming step (S14), and a reflective film forming step (S16).

Grid structure material forming step (S10)
First, in S10, a grid structure material 23 made of a transparent organic material (eg, ultraviolet curable resin or thermosetting resin) is laminated by coating or the like on a substrate 10 made of a transparent inorganic material (eg, glass). do. As the inorganic material for the substrate 10, various materials described above can be used. Moreover, as the organic material of the grid structure 20, various materials described above can be used. Furthermore, the film thickness of the grid structure material 23 may be appropriately adjusted according to the dimensions of the base portion 21 and the ridges 22 of the grid structure 20 formed by nanoimprinting in S20.

Nanoimprinting step (S12) and grid structure forming step (S14)
Next, in S12, the grid structure 20 is formed on the substrate 10 in S14 by nanoimprinting the grid structure material 23. FIG. The grid structure 20 is a fine concave-convex structure in which a base portion 21 provided on the substrate 10 and a plurality of ridges 22 protruding from the base portion 21 are integrally formed. The fine relief structure is a structure having fine protrusions and recesses on the order of several nanometers to several tens of nanometers, for example.

In the nanoimprint step of S12, using the master 60 on which the reversed shape of the fine unevenness of the grid structure 20 is formed, the fine unevenness of the master 60 is transferred to the surface of the grid structure material 23 (S12). As a result, an uneven pattern composed of the base portion 21 , the ridge portion 22 and the recess portions 24 is formed on the grid structure material 23 . Further, in the nanoimprinting step, the grid structure material 23 to which the uneven pattern has been transferred is cured by irradiating the grid structure material 23 with energy rays along with the transfer of the uneven pattern. is formed (S14). For example, when the grid structure material 23 is made of an ultraviolet curable resin, the ultraviolet curable resin to which the concave-convex pattern has been transferred is irradiated with ultraviolet rays to the grid structure material 23 using the ultraviolet irradiation device 66. may be cured. Alternatively, when the grid structure material 23 is made of a thermosetting resin, a heating device 68 such as a heater is used to heat the grid structure material 23, thereby curing the thermosetting resin onto which the uneven pattern has been transferred. may let

In steps S<b>12 and S<b>14 described above, as the protruded streak portion 22 of the grid structure 20 , the protruded streak portion 22 having a tapered shape whose width becomes narrower as the distance from the base portion 21 increases is formed. 11 has a trapezoidal (tapered) shape, it may have various other tapered shapes as shown in FIG.

As described above, in the present embodiment, in the nanoimprinting step S12, since the ridges 22 having a tapered shape are imprinted, the master 60 can be easily peeled off from the grid structure material 23. Excellent. Also, the protruding streaks 22 of the grid structure 20 can be accurately formed into a desired shape without losing their shape.

Reflective film forming step (S16)
Next, in S<b>16 , the reflective film 30 that partially covers the ridges 22 of the grid structure 20 is formed using a metal material such as Al or Ag. The reflective film 30 is an example of a functional film that imparts a predetermined function to the polarizing element 1 . The reflective film 30 is a metal thin film (grid of fine metal wires) for reflecting incident light incident on the grid structure 20 of the polarizing element 1 .

In this reflective film forming step S16, the reflective film 30 is formed as follows. That is, the reflective film 30 covers the top end 22a and at least one of the side surfaces 22b of the ridge portion 22, and does not cover the lower side surfaces 22b of the ridge portion 22 and the base portion 21. A reflective film 30 is formed. Further, the reflective film 30 is formed so that the surface of the reflective film 30 covering the ridges 22 is rounded and bulges in the width direction of the ridges 22 . In addition, the maximum width W _MAX (grid maximum width W _MAX ) of the reflective film 30 covering the ridges 22 should be equal to or greater than the width _{WB of the bottom of the ridges (grid bottom width W B )} . , forming the reflective film 30 .

As a method for forming such a reflective film 30, for example, as shown in FIG. 5, sputtering or vapor deposition can be used. A metal material is alternately sputtered or vapor-deposited from oblique directions with respect to the ridges 22 of the grid structure 20 to form the reflective film 30 . As a result, the reflective film 30 having a desired shape can be suitably formed so as to cover the apex of the ridge 22 in a round shape.

By forming the reflective film 30 in this manner, the ridges 22 of the grid structure 20 and the reflective film 30 have the above-described special tree shape. As a result, as described above, even when light enters the polarizing element 1 obliquely at a relatively large and wide range of incident angles θ (for example, 30 to 60°), it is included in the obliquely incident light. It is possible to maintain the transmission axis transmittance Tp of P-polarized light at a high value, and ensure the transparency of P-polarized light (transmitted light). Therefore, since the value of Tp×Rs can be maintained at a high value (for example, 70% or more), the polarization splitting characteristics of the polarizing element 1 with respect to obliquely incident light can be improved.

In addition, in the method for manufacturing the polarizing element 1 according to the present embodiment, after the reflecting film forming step S16 shown in FIG. formation step). The protective film 40 is preferably formed so as to cover the entire surfaces of the grid structure 20 and the reflective film 30 . As a material for the protective film 40, various materials described above can be used.

The method for manufacturing the polarizing element 1 according to this embodiment has been described above. Through the above-described steps, the polarizing element 1 having excellent polarizing properties and heat dissipation properties can be manufactured without increasing the manufacturing cost of the polarizing element 1 or making the manufacturing process complicated.

Here, in order to compare with the manufacturing method according to the present embodiment, a conventional method for manufacturing a wire grid polarizing element will be briefly described with reference to FIG.

As shown in FIG. 12, in the conventional wire grid polarization element manufacturing method, first, a metal film 80 is formed on the substrate 10 in order to form a convex grid shape (S20). In this step S20, a reflective film made of a material that reflects light in the used band, for example, a metal film 80 of aluminum or the like is formed on the substrate 10 made of an inorganic material such as glass by sputtering or vapor deposition.

Next, using a photolithographic technique, the resist mask 70 is patterned on the metal film 80 (S22). After that, by etching the metal film 80 using a vacuum dry etching device or the like, a convex shape made of the metal film 80 is formed (S24). For example, at this time, if the etching selectivity between the resist mask 70 and the metal film 80 cannot be obtained, an oxide film such as SiO ₂ is further formed on the metal film 80 by sputtering or the like, and then a photolithographic technique is used to form a film thereon. A resist mask 70 is formed. Thereafter, after removing the resist mask 70 from the metal film 880 (S26), a protective film 40 made of a SiO ₂ film or the like is formed by CVD or the like, and a water-repellent/oil-repellent coating process is performed as necessary (S28). ).

In the steps S20 to S28 of the conventional manufacturing method described above, the process of manufacturing a reflective wire grid polarizing element having a basic configuration is shown. Requires process. Therefore, it is presumed that the conventional wire grid polarizing element manufactured by the processes shown in S20 to S28 in FIG. 12 is expensive to manufacture and takes a long time to manufacture. In addition, when mass-producing polarizing elements, it is necessary to prepare multiple units of high-precision and expensive etching equipment and photolithography equipment according to the production volume in order to form fine convex shapes smaller than the wavelength of light. , capital investment is expected to be higher.

On the other hand, the manufacturing method of the polarizing element 1 according to the present embodiment (see FIG. 11) forms the grid structure 20 using an imprinting technique such as nanoimprinting. ), manufacturing costs, manufacturing time, and equipment investment can be greatly reduced.

In the method for manufacturing the polarizing element 1 according to the present embodiment, the grid structure material 23 is nanoimprinted (S12 in FIG. 11), but the nanoimprint conditions are not particularly limited. For example, as shown in S12 in FIG. 11 , a replica master (or an original master) is used as the master 60, and while nanoimprinting is performed, the grid structure material 23 is subjected to UV irradiation, heating, or the like to form an uneven pattern. Curing the grid structure material 23 in the imprinted state. After that, the master 60 is released from the cured grid structure material 23 . Thereby, the grid structure 20 in which the base portion 21 and the ridge portion 22 are formed can be molded by transfer.

Note that the master plate 60 used in the nanoimprint step S12 (FIG. 11) in the method for manufacturing the polarizing element 1 according to this embodiment can be produced by photolithography, for example, as shown in FIG. 13A and 13B are process diagrams showing a method of manufacturing the master 60 according to this embodiment.

As shown in FIG. 13, first, after forming a master metal film 62 on a master substrate 61 (S30), a resist mask 70 is formed on the master metal film 62 (S32). Next, the master disk metal film 62 is etched using the resist mask 70, and grooves 65 corresponding to the ridges 22 of the grid structure 20 are formed in the etched master disk metal film 62 (S34). .

After that, the master 60 is obtained by removing the resist mask 70 from the master metal film 62 (S36). The master 60 has a fine relief structure including a plurality of projections 63 and grooves 65 formed on a master substrate 61 . The fine ruggedness structure on the surface of the master 60 has an inverted shape of the fine ruggedness structure on the surface of the grid structure 20 of the polarizing element 1 . The grooves 65 of the master plate 60 have a reversed shape of the ridges 22 of the grid structure 20, and the ridges 63 of the master 60 have a reversed shape of the recesses 24 between the ridges 22, 22 of the grid structure 20. have

Furthermore, the manufacturing method according to this embodiment may include a step (S38) of forming a release film coat 64 on the surface of the fine concavo-convex structure of the master 60, if necessary. By providing the release film coat 64 on the surface of the master 60, the master 60 can be easily removed from the grid structure material 23 after the grid structure material 23 is nanoimprinted in the nanoimprint step (S12) shown in FIG. It can be peeled off, and the releasability can be further improved.

<4. Projection Display>
Next, a projection display apparatus to which the wire grid polarization element 1 according to this embodiment is applied will be described with reference to FIG.

The projection display apparatus according to this embodiment includes the wire grid polarization element 1 according to this embodiment described above. By including the polarizing element 1 in the projection display apparatus according to the present embodiment, it is possible to realize excellent polarization characteristics, heat resistance, heat dissipation, and the like of the polarizing element 1 .

Here, a projection display device projects light toward an object and irradiates the projected light (projection light) onto a display surface (projection surface) of the object to create a virtual image such as an image or video. is a device that displays Types of projection display devices include, for example, a head-up display device (HUD), a projector device, and the like.

<4.1. Head-up display device>
First, referring to FIG. 14, a head-up display device 100 including the wire grid polarization element 1 according to this embodiment will be described. FIG. 14 is a schematic diagram showing an example of the head-up display device 100 according to this embodiment.

As shown in FIG. 14, a head-up display device 100 according to this embodiment includes the wire grid polarization element 1 according to this embodiment described above. By including the polarizing element 1 in the head-up display device 100, it is possible to improve polarization characteristics, heat resistance, and heat dissipation. A head-up display incorporating a conventional polarizing element is inferior in heat dissipation, so it is considered that heat resistance is not sufficient in consideration of long-term use and future high brightness and enlarged display.

As shown in FIG. 14, the head-up display device 100 includes a light source 2, a display element 3 that emits a display image, a reflector 4 that reflects the display image onto a display surface 5, and a cover provided at an opening of a housing 7. a part 6; In the head-up display device 100, the arrangement of the polarizing element 1 is not particularly limited. For example, the polarizing element 1 can be placed between the display element 3 and the reflector 4, as shown in FIG.

Here, the head-up display device 100 may be a vehicle head-up display device provided in a vehicle. A vehicle head-up display device displays an image on a transflective plate (corresponding to a “display surface 5”) such as a windshield of a vehicle or a combiner. A vehicle head-up display device is, for example, a video display device that is arranged on a dashboard of a vehicle, projects video light onto a windshield (display surface 5), and displays driving information as a virtual image.

The head-up display device 100 is configured to emit a display image from below toward the windshield surface (display surface 5). Therefore, the sunlight may enter the display element 3 in a direction opposite to the emission direction of the display image. The head-up display device 100 according to this embodiment is provided with a reflector 4 for reflecting and enlarging a display image for the purpose of miniaturization and enlargement of the display image. In such a case, in the conventional head-up display device, sunlight incident on the reflector from the outside is condensed in the vicinity of the display element, and the heat may cause deterioration or failure of the display element.

On the other hand, in the head-up display device 100 according to the present embodiment, the hybrid polarizing element 1 having excellent heat dissipation and heat resistance is provided for the purpose of preventing sunlight from entering the display element 3. It is This polarizing element 1 can stably exhibit a polarizing function even at a high temperature of about 200° C., for example. Therefore, for example, even in a high-temperature environment such as in a car in summer, the sunlight entering the reflector 4 from the outside can be blocked by the polarizing element 1 and prevented from reaching the display element 3. 3 deterioration and failure can be suppressed.

Note that the components of the head-up display device 100 shown in FIG. 14 are examples of basic components, and the components of the projection display device are not limited to the example of FIG. Other components can be appropriately provided according to performance and the like.

In addition, by using the polarizing element 1 as a pre-polarizing plate arranged in front of the display element 3, the polarizing element 1 allows the display image emitted from the display element 3 to pass therethrough while directing sunlight to the display element 3. Injection can be suppressed. Therefore, the heat resistance and durability of the head-up display device 100 can be further enhanced.

In addition, the arrangement of the wire grid polarization element in the projection display device is not limited to the example of the arrangement of the polarization element 1 in the head-up display device 100 shown in FIG. It can be selected and changed as appropriate. For example, although not shown, the polarizing element 1 can be placed between the display element 3 and the light source 2 . Also, although not shown, the polarizing element 1 can be incorporated into the reflector 4 . Furthermore, the cover portion 6 provided in the head-up display device 100 shown in FIG.

Also, although not shown, a heat dissipation member 50 (see FIG. 9) may be provided around the polarizing element 1 installed in the head-up display device 100 . The heat dissipation member 50 can further improve the heat dissipation of the polarizing element 1, so that the polarization characteristics and heat resistance of the polarizing element 1 can be further improved.

<4.2. Projection Display Device Equipped with Polarizing Beam Splitter>
Next, a projection display apparatus using the reflective wire grid polarization element 1 according to this embodiment as the polarization beam splitter 230 will be described with reference to FIGS. 15 to 17. FIG. In the following, first, matters common to three specific examples of the projection display apparatuses 200A, 200B, and 200C (hereinafter collectively referred to as the "projection display apparatus 200") shown in FIGS. explain. After that, each specific example shown in FIGS. 15 to 17 will be individually described.

As shown in FIGS. 15 to 17, the projection display device 200 includes a light source 210, a PS converter 220, a polarizing beam splitter 230, a reflective liquid crystal display element 240, and a lens 250. FIG. A retardation compensator (not shown) may be installed between the polarizing beam splitter 230 and the reflective liquid crystal display element 240 .

The light source 210 may be a point light source having one light emitting portion, or may be a light source having a plurality of light emitting portions such as LEDs. Also, the light emitted from the light source 210 may be parallel light or diffuse light. Therefore, the light from the light source 210 is incident on the polarizing beam splitter 230 (reflective wire grid polarizer) at an incident angle θ within a predetermined range (for example, a range of 45°±15°) centered on 45°. may be incident.

The PS converter 220 is a polarization conversion element for converting the light from the light source 210 into specific polarized light (for example, P polarized light or S polarized light). The PS converter 220 may convert the light from the light source 210 into P-polarized light or S-polarized light.

The polarizing beam splitter 230 is composed of a reflective wire grid polarizer. A reflective wire grid polarizer is an example of the wire grid polarizer 1 according to this embodiment. The polarizing beam splitter 230 is arranged so that the light from the light source 210 is incident at an incident angle θ within a predetermined range including 45°. The incident angle θ in this predetermined range is, for example, the above-mentioned 45°±15°, that is, 30° or more and 60° or less.

For example, in FIGS. 15-17, the polarizing beam splitter 230 is arranged such that the incident light from the light source 210 is incident on the polarizing beam splitter 230 mainly at an incident angle θ of 45°. is arranged at an angle of 45° to the Further, the polarizing beam splitter 230 is attached to the reflective liquid crystal display element 240 so that the incident light from the reflective liquid crystal display element 240 is incident on the polarizing beam splitter 230 mainly at an incident angle θ of 45°. It is arranged with an inclination of 45°.

Polarizing beam splitter 230 splits incident light into a first polarization (S-polarization) and a second polarization (P-polarization). For example, the polarizing beam splitter 230 may separate the S-polarized light from the P-polarized light by reflecting the first polarized light (S-polarized light) and transmitting the second polarized light (P-polarized light) of the incident light. Conversely, the polarizing beam splitter 230 separates S-polarized light from P-polarized light by reflecting the second polarized light (P-polarized light) and transmitting the first polarized light (S-polarized light) of the incident light. may

When the polarization beam splitter 230 reflects desired polarized light, the surface of the polarization beam splitter 230 (that is, the uneven surface on the side of the polarizing element 1 on which the grid structure 20 is formed) receives light including the polarized light to be reflected. A polarizing beam splitter 230 is positioned to be incident. For example, as shown in FIG. 15, when the polarization beam splitter 230 reflects the S-polarized light incident from the PS converter 220, the surface of the polarization beam splitter 230 may be directed toward the PS converter 220 side from which the S-polarized light is emitted. . On the other hand, as shown in FIG. 16, when the polarizing beam splitter 230 reflects the S-polarized light incident from the reflective liquid crystal display element 240, the surface of the polarizing beam splitter 230 is the reflective liquid crystal display element that emits the S-polarized light. You should turn to the 240 side

The reflective liquid crystal display element 240 is a display element that reflects incident light and emits light representing a display image. As shown in FIGS. 15 and 17, the reflective liquid crystal display element 240 is arranged so that the first polarized light (S-polarized light) reflected by the polarization beam splitter 230 is incident on the surface of the reflective liquid crystal display element 240 . may Alternatively, as shown in FIG. 16, the reflective liquid crystal display element 240 is arranged so that the second polarized light (P-polarized light) transmitted through the polarization beam splitter 230 is incident on the surface of the reflective liquid crystal display element 240. good too.

In addition, as shown in FIGS. 15 and 17, the reflective liquid crystal display element 240 reflects and modulates the incident first polarized light (S polarized light) to produce a second polarized light (P polarized light) representing a display image. is emitted. However, the present invention is not limited to such an example, and as shown in FIG. 16, the reflective liquid crystal display element 240 reflects and modulates the incident second polarized light (P polarized light) to convert the incident second polarized light (P polarized light) into the first polarized light representing the display image. (S-polarized light) may be emitted.

The lens 250 magnifies the light representing the display image emitted from the reflective liquid crystal display element 240 and outputs it to the outside. A lens 250 is arranged so that light representing a display image emitted from the reflective liquid crystal display element 240 is incident through the polarizing beam splitter 230 . For example, as shown in FIGS. 15 and 17, the second polarized light (P polarized light) reflected and modulated by the reflective liquid crystal display element 240 is transmitted through the polarized beam splitter 230 and is incident on the lens 250. , the lens 250 may be arranged. Alternatively, as shown in FIG. 16, the first polarized light (S-polarized light) reflected and modulated by the reflective liquid crystal display element 240 is reflected by the polarization beam splitter 230 and is incident on the lens 250. may be placed.

As described above, in the projection display apparatus 200 according to this embodiment, the wire grid polarization element 1 according to this embodiment described above is used as the polarization beam splitter 230 . Therefore, the polarizing beam splitter 230 provides reflectivity for S-polarized light, transmissiveness for P-polarized light, and Tp× It has an excellent Rs characteristic and is excellent in the characteristic of separating obliquely incident light into P-polarized light and S-polarized light.

Next, specific examples of the projection display apparatuses 200A, 200B, and 200C shown in FIGS. 15 to 17 will be individually described.

As shown in FIG. 15, the projection display apparatus 200A according to the first specific example of the present embodiment includes a light source 210, a PS converter 220, a polarizing beam splitter 230, a reflective liquid crystal display element 240, and a lens 250. Prepare.

The light emitted from light source 210 is unpolarized, and contains equal proportions of P-polarized and S-polarized components. Therefore, if only one polarized light is selected and extracted by the polarizing beam splitter 230 composed of the polarizing element 1, the amount of light is reduced to about half. Therefore, the PS converter 220 converts the light emitted from the light source 210 into either the first polarized light (S polarized light) or the second polarized light (P polarized light). As a result, the reduction in the amount of polarized light extracted by the polarizing beam splitter 230 can be suppressed, and the light utilization efficiency can be improved. For example, the PS converter 220 shown in FIG. 15 converts the light from the light source 210 into the first polarized light (S polarized light).

The light converted into S-polarized light by the PS converter 220 is incident on the polarization beam splitter 230 arranged at an angle of about 45°. The polarizing beam splitter 230 reflects the first polarized light (S polarized light) and emits it toward the reflective liquid crystal display element 240 at an emission angle of 45°. The reflective liquid crystal display element 240 modulates and reflects the first polarized light (S polarized light) to generate a second polarized light (P polarized light) representing a display image, and converts the second polarized light (P polarized light) into polarized light. It is emitted toward the beam splitter 230 . The second polarized light (P polarized light) is transmitted through the polarizing beam splitter 230, magnified by the lens 250, and projected onto a display surface (not shown) to display a display image.

The projection display apparatus 200A having the above configuration includes, as the polarization beam splitter 230, a reflective wire grid polarizing plate composed of the wire grid polarizing element 1 according to this embodiment. As a result, the polarization separation characteristics of the polarization beam splitter 230 can be improved with respect to incident light obliquely and incident light with a wide incident angle θ, and the heat dissipation and heat resistance of the polarization beam splitter 230 and the projection display device 200A can be improved. can do.

On the other hand, a projection display apparatus (not shown) equipped with a conventional polarizing element as a polarizing beam splitter is inferior in heat dissipation of the polarizing element. For this reason, it is considered that the heat resistance is not sufficient from the viewpoint of long-term use, high brightness, and magnified display. Moreover, the incident angle θ of the light incident on the polarization beam splitter is not limited to 45°, but any angle within a predetermined range (for example, about 45°±15°) around 45°. Thus, even when obliquely incident light with a large and wide range of incident angles θ is incident on the polarizing beam splitter, the polarizing beam splitter converts obliquely incident light into S-polarized light and P-polarized light regardless of the incident angle θ. A performance capable of suitably separating polarized light is required. However, in a conventional polarizing beam splitter using a polarizing element, the polarization splitting characteristics for the obliquely incident light are poor, so the light utilization efficiency deteriorates, and the image quality of the displayed image is adversely affected by uneven brightness. was

In this respect, the polarizing beam splitter 230 of the projection display apparatus 200A according to the first specific example of the present embodiment has excellent polarization splitting characteristics for obliquely incident light with a large and wide range of incident angles θ as described above. Therefore, in the projection display apparatus 200A, it is possible to improve the light utilization efficiency, reduce luminance unevenness, and improve the image quality of the displayed image.

Further, the projection display device is not limited to the example of the projection display device 200A shown in FIG. 15. For example, the projection display device 200B shown in FIG. The components and arrangement of the projection display device can be changed as appropriate.

As shown in FIG. 16, the projection display apparatus 200B according to the second specific example of the present embodiment includes a light source 210, a PS converter 220, a polarizing beam splitter 230, a reflective liquid crystal display element 240, and a lens 250. Prepare.

In the projection display device 200B, the PS converter 220 converts the light from the light source 210 into second polarized light (P polarized light). The light converted into P-polarized light by the PS converter 220 is transmitted through the polarizing beam splitter 230 arranged at an angle of about 45° and is incident on the reflective liquid crystal display element 240 . The reflective liquid crystal display element 240 modulates and reflects the second polarized light (P polarized light) to generate a first polarized light (S polarized light) representing a display image, and converts the first polarized light (S polarized light) into polarized light. It is emitted toward the beam splitter 230 . Polarizing beam splitter 230 reflects the first polarized light (S-polarized light) and emits it toward lens 25 at an emission angle of 45°. The first polarized light (S polarized light) is magnified by the lens 250 and projected onto a display surface (not shown) to display a display image.

Similar to the projection display device 200A (see FIG. 15) described above, the projection display device 200B having the above configuration is excellent in polarization separation characteristics with respect to obliquely incident light, can improve the efficiency of light utilization, and can reduce luminance unevenness. can be reduced to improve the quality of the displayed image.

Further, as shown in FIG. 17, the projection display apparatus 200C according to the third specific example of the present embodiment includes a light source 210, a polarizing beam splitter 230, a reflective liquid crystal display element 240, a lens 250, and a light absorber. 260, but does not include the PS converter 220 described above.

In the projection display apparatus 200C, the non-polarized light emitted from the light source 210 is directly incident on the polarizing beam splitter 230 arranged at an oblique angle of about 45°. The polarizing beam splitter 230 reflects the first polarized (S-polarized) component of the unpolarized light and emits it toward the reflective liquid crystal display element 240 at an emission angle of 45°. On the other hand, of the non-polarized light incident on the polarization beam splitter 230 , the second polarized (P-polarized) component is transmitted through the polarization beam splitter 230 and incident on the light absorber 260 . Since most of the components of this second polarized light (P polarized light) are absorbed by the light absorber 260, unnecessary second polarized light (P polarized light) is incident on other optical systems in the projection display apparatus 200C. It is possible to suppress

The reflective liquid crystal display element 240 modulates and reflects the component of the first polarized light (S polarized light) incident from the polarizing beam splitter 230 to generate the second polarized light (P polarized light) representing the display image. A second polarized light (P polarized light) is emitted toward the polarizing beam splitter 230 . The second polarized light (P polarized light) is transmitted through the polarizing beam splitter 230, magnified by the lens 250, and projected onto a display surface (not shown) to display a display image.

Since the PS converter 220 is not provided in the projection display apparatus 200C having the above configuration, the light absorber 260 absorbs the second polarized (P-polarized) component of the non-polarized light emitted from the light source 210. and is not used to display the display image. As a result, the amount of light in the displayed image is reduced by about half. However, since the cost and installation space required for the PS converter 220 can be reduced, and the number of parts of the projection display device 200C can be reduced, there is an advantage that the cost of the projection display device 200C can be reduced and the size of the projection display device 200C can be reduced. .

A specific example of the projection display apparatus 200 using the reflective wire grid polarization element 1 according to the present embodiment as the polarization beam splitter 230 has been described above. Note that the projection display device is not limited to the specific example of the projection display device 200 shown in FIGS. Other components may be provided as appropriate.

<5. Vehicle>
Next, a vehicle equipped with the image display device according to this embodiment will be described.

A vehicle (not shown) according to this embodiment includes a projection display device having the wire grid polarization element 1 according to this embodiment described above. As long as the vehicle can be equipped with a projection display device, it can be any vehicle such as a passenger car, a light car, a bus, a truck, a racing car, a construction vehicle, or any other large vehicle. Alternatively, various vehicles such as motorcycles, trains, linear motor cars, and rides for attractions may be used.

The vehicle according to the present embodiment can project and display a display image on a display surface provided in the vehicle (for example, the display surface 5 shown in FIG. 14) by the polarizing element 1 and the projection display device. The display surface is preferably a transflective plate such as a vehicle windshield, side glass, rear glass, or combiner. However, the display surface is not limited to this example, and may be the surface of various parts, members, in-vehicle equipment, etc. provided in the vehicle as long as it is the surface of an object on which a display image can be projected.

The projection display device provided in the vehicle according to the present embodiment is, for example, the head-up display device 100 shown in FIG. 14, or the projection display device 200 having the polarizing beam splitter 130 shown in FIGS. . However, the projection display device is not limited to such an example, and any device capable of projecting or displaying an image can be used as a projector mounted on a vehicle, a car navigation device, a terminal device having an image display function, or any other type of image display device. It may be a device.

As described above, in the head-up display device 100, as shown in FIG. 14, sunlight may enter the head-up display device 100 from the outside of the vehicle through the windshield (display surface 5). . The heat of the sunlight may cause deterioration or failure of the display element 3 . Therefore, in order to prevent sunlight from entering the display element 3 , the above-described hybrid wire grid polarizing element 1 is provided in the head-up display device 100 . Since this polarizing element 1 has a hybrid structure with high thermal conductivity, it is excellent in heat dissipation and heat resistance. Therefore, the polarizing element 1 can block the sunlight entering the head-up display device 100 from the outside and prevent it from reaching the display element 3 , so that the display element 3 can be prevented from malfunctioning or being damaged. Furthermore, since the polarizing element 1 is excellent in heat dissipation and heat resistance, damage to the polarizing element 1 itself can be prevented.

Similarly, even when the projection display apparatus 200 shown in FIGS. 15 to 17 is installed in a vehicle, the polarizing element 1 used as the polarizing beam splitter 230 can block sunlight from the outside, so that the reflective liquid crystal display element 240 and other parts can be prevented from malfunctioning or being damaged. Furthermore, damage to the polarizing element 1 itself, which is excellent in heat dissipation and heat resistance, can be prevented.

As described above, in the projection display device provided in the vehicle according to the present embodiment, excellent polarization characteristics (sunlight blocking performance, polarization separation characteristics, etc.) can be obtained by the polarizing element 1, and the projection display device has excellent characteristics. Heat resistance and durability can also be achieved.

The vehicle is not particularly limited as long as it is equipped with the projection display device and the polarizing element described above, and other conditions can be appropriately set and changed according to the performance required of the vehicle.

Next, examples of the present invention will be described. However, the examples described below are specific examples for explaining the configuration and effects of the polarizing element 1 according to the present embodiment described above, and the present invention is limited to the following examples. not a thing

As an example of the present invention, a model of the wire grid polarizing element 1 according to the present embodiment described above was produced, and various characteristics thereof were simulated to evaluate the wire grid polarizing element 1 . In addition, in order to compare with the examples of the present invention, a model of a conventional wire grid polarizing element was created, and simulations and evaluations were performed in the same manner. In the following, for convenience of explanation, reference numerals representing constituent elements of the polarizing element (substrate 10, grid structure 20, base portion 21, ridge portion 22, reflective film 30, etc.) and The symbols representing the various dimensions of these components are given the same reference numerals and symbols.

Symbols representing various dimensions of the polarizing element 1 used in the following description are as follows.
P: Pitch of the ridge portion 22 W _T : Width of the top portion of the ridge portion 22 (width of the top portion of the ridge portion)
W _M : Width at the central position in the height direction of the protruding portion 22 (protrusive portion central width)
W _B : Width of the bottom of the ridge 22 (grid bottom width)
W _MAX : Maximum width (maximum grid width) of the reflective film 30 covering the ridge 22
H: Height of ridge 22 Hx: Height of portion of side surface 22b of ridge 22 covered with reflective film 30 Dt: Thickness of reflective film 30 covering tip 22a of ridge 22 (reflection Tip thickness of membrane 30)
Ds: Thickness of the reflective film 30 covering the side surface 22b of the ridge 22 (thickness of the side surface of the reflective film 30)
Rc: coverage ratio of the side surface 22b of the ridge portion 22 by the reflective film 30 Rr: openness ratio of the side surface 22b of the ridge portion 22 by the reflective film 30 θ: incident angle of incident light λ: wavelength of incident light

(Conventional example 1)
First, conventional example 1 will be described with reference to FIG.

As shown in FIG. 18A, a model of the polarizing element 1 according to Conventional Example 1 was produced. A polarizing element 1 according to Conventional Example 1 includes a substrate 10 made of glass and a grid structure 20 made of an ultraviolet curable resin (acrylic resin). The grid structure 20 has a base portion 21 provided along the surface of the substrate 10 and a plurality of ridges 22 protruding from the base portion 21 in a grid pattern. The cross-sectional shape of the ridge portion 22 is rectangular and not tapered. The reflective film 30 that covers the ridges 22 is an Al film. The reflective film 30 is formed so as to cover the entire tip 22 a and one side surface 22 b of the protruding portion 22 and part of the base portion 21 . However, the reflective film 30 does not cover the other side surface 22b of the ridge portion 22 at all. As described above, the reflective film 30 of the conventional example 1 is unevenly formed only on one side of the ridge portion 22, and the other side of the ridge portion 22 is not covered with the reflective film 30 and is open. ing.

The dimensions and shapes of each part of the model of the polarizing element 1 according to Conventional Example 1 are as follows.
P: 144 nm
_WT : 32.5 nm
W _B : 32.5 nm
_WMAX : 55nm
H: 220 nm
Hx: 220 nm (one side), 0 nm (other side)
Dt: 35 nm
Ds: 22.5 nm (maximum value)
Rc: 100% (one side), 0% (other side)
Rr: 0% (one side), 100% (other side)
θ: 0° to +60°
λ: 430-680nm

After that, the model of the polarizing element 1 according to Conventional Example 1 manufactured as described above is simulated by changing the incident angle θ, and the transmission axis transmittance (Tp), the reflection axis reflectance (Rs), and the polarized beam Tp×Rs required for the splitter (PBS) was calculated. The incident angle θ was set to 0° to +60°. As the values of Tp and Rs, the wavelength λ of the incident light is varied in the range of 430 to 680 nm, and the average value of multiple values of Tp and Rs calculated for the incident light of each wavelength λ is used. board. The relationships between Tp, Rs, Tp×Rs calculated as described above and θ are shown in the graphs of FIGS. 18(b) to (d).

As shown in FIG. 18, in Conventional Example 1, the reflective film 30 is unevenly distributed on one side of the ridge 22, and the coverage Rc of the one side is 100%. Therefore, as the incident angle θ increases, Rs increases gradually, but Tp decreases significantly, so Tp×Rs also decreases significantly. For example, in the range of θ>45°, Tp decreased to 76% or less and Tp×Rs decreased to 68% or less. Therefore, when the polarizing element 1 according to Conventional Example 1 is used as a polarizing beam splitter, the polarization splitting characteristics (Tp×Rs characteristics) are poor, especially for obliquely incident light with a large incident angle θ of 45° or more. It can be seen that there is a problem that the Tp×Rs characteristics required for the beam splitter cannot be obtained.

(Conventional example 2)
Next, the conventional example 2 will be described with reference to FIG.

As shown in FIG. 19A, a model of the polarizing element 1 according to Conventional Example 2 was produced. The model of Conventional Example 2 is similar to the model of Conventional Example 1 described above. However, in Conventional Example 2, as the incident angle θ, an incident angle (θ=0° to +60°) in the + direction that is incident on one side of the ridge 22 from an oblique direction, and Two directions of incident angle (θ=0° to −60°) in the − direction, which is incident from an oblique direction to the side, were used.

The dimensions and shapes of each part of the model of the polarizing element 1 according to Conventional Example 2 are as follows.
P: 144 nm
_WT : 32.5 nm
W _B : 32.5 nm
_WMAX : 55nm
H: 220 nm
Hx: 220 nm (one side), 0 nm (other side)
Dt: 35 nm
Ds: 22.5 nm (maximum value)
Rc: 100% (one side), 0% (other side)
Rr: 0% (one side), 100% (other side)
θ: 0° to +60°, 0° to -60°
λ: 430-680nm

After that, the model of the polarizing element 1 according to Conventional Example 2 manufactured as described above is simulated by changing the incident angle θ, and the transmission axis transmittance (Tp), the reflection axis reflectance (Rs), and the polarized beam Tp×Rs required for the splitter (PBS) was calculated. At this time, Tp, Rs, and Tp×Rs were calculated when the incident angle θ was in the + direction and in the − direction. As the values of Tp and Rs, the wavelength λ of the incident light was changed in the range of 430 to 680 nm, and the average value of a plurality of Tp and Rs values calculated for the incident light of each wavelength was used. . The relationships between Tp, Rs, Tp×Rs calculated as described above and θ are shown in graphs of FIGS. 19(b) to (d).

As shown in FIG. 19, in Conventional Example 2, the reflective film 30 is unevenly distributed on one side of the ridge portion 22 in the same manner as in Conventional Example 1, and the coverage Rc of the one side is 100%. As a result, as shown in FIG. 19B, in Conventional Example 2, as in Conventional Example 1, Tp(+) becomes more pronounced as the incident angle θ increases with respect to incidence of obliquely incident light from the + direction. decreased to Furthermore, in Conventional Example 2, Tp(-) decreases as the absolute value of the negative incident angle θ increases even when obliquely incident light is incident from the - direction. , Tp(+).

Specifically, in Conventional Example 2, when the absolute value of θ is in the range of 30° to 60°, the difference between Tp(+) and Tp(−) is 5% or more, and Tp×Rs(+) and Tp×Rs(−) is 4% or more. From this result, it was confirmed that, in Conventional Example 2, the polarization characteristics of the polarizing element 1 have left-right asymmetry depending on whether the incident direction of the obliquely incident light is the positive direction or the negative direction.

As in Conventional Example 2 above, when the difference in Tp due to the difference in the incident direction of the obliquely incident light (for example, the difference between +45° and −45°) increases, the observer perceives the difference in the brightness of the displayed image. It can be seen that there is a problem that the video state becomes inappropriate. Further, when the polarizing element 1 according to Conventional Example 2 is used as a polarizing beam splitter, the polarization splitting characteristics (Tp×Rs characteristics) are poor particularly for obliquely incident light with a large incident angle θ of 45° or more, and the polarization It can be seen that there is also the problem that the Tp×Rs characteristics required for the beam splitter cannot be obtained.

(Conventional example 3)
Next, with reference to FIG. 20, conventional example 3 will be described.

As shown in FIG. 20(a), a model of the polarizing element 1 according to Conventional Example 3 was produced. A polarizing element 1 according to Conventional Example 3 includes a substrate 10 made of glass and a grid structure 20 made of ultraviolet curable resin (acrylic resin). The grid structure 20 has a base portion 21 provided along the surface of the substrate 10 and a plurality of ridges 22 protruding from the base portion 21 in a grid pattern. The cross-sectional shape of the ridge portion 22 is rectangular and not tapered. The reflective film 30 that covers the ridges 22 is an Al film. The reflective film 30 is formed so as to cover most (approximately 85%) of the tip 22a of the protruding portion 22 and the side surfaces 22b on both sides. In this manner, the reflective film 30 of Conventional Example 3 covers most of the tip 22a and both side surfaces 22b of the protruding portion 22. As shown in FIG. In addition, the reflecting film 30 of Conventional Example 3 has a rectangular shape and has two angular corner portions at both left and right ends of the top portion of the reflecting film 30. It is different from the rounded bulging shape like 30.

The dimensions and shapes of each part of the model of the polarizing element 1 according to Conventional Example 3 are as follows.
P: 140 nm
_WT : 35 nm
W _B : 35 nm
_WMAX : 65nm
H: 230 nm
Hx: 196nm
Dt: 30 nm
Ds: 15 nm (maximum value)
RC: 85%
Rr: 15%
θ: 0° to +60°
λ: 430-680nm

After that, the model of the polarizing element 1 according to Conventional Example 3 manufactured as described above is simulated by changing the incident angle θ in the same manner as in Conventional Example 1, and Tp, Rs, and Tp×Rs are calculated. bottom. The incident angle θ was set to 0° to +60°. The relationships between Tp, Rs, Tp×Rs calculated in this way and θ are shown in the graphs of FIGS. 20(b) to (d).

As shown in FIG. 20, in Conventional Example 3, although the covering mode is different from that in Conventional Example 1, the reflective film 30 covers most of both side surfaces 22b of the ridge 22, and the coverage Rc is As large as 85%. Therefore, in Conventional Example 3, as in Conventional Example 1, as the incident angle θ increases, Rs increases gradually, but Tp decreases significantly, so Tp×Rs also decreases significantly. For example, in the range of θ>45°, Tp decreased to 73% or less and Tp×Rs decreased to 65% or less. Therefore, when the polarizing element 1 according to Conventional Example 3 is used as a polarizing beam splitter, the polarization splitting characteristics (Tp×Rs characteristics) are poor, especially for obliquely incident light with a large incident angle θ of 45° or more. It can be seen that there is a problem that the Tp×Rs characteristics required for the beam splitter cannot be obtained.

(Example 1)
Next, Embodiment 1 of the present invention will be described with reference to FIGS. 21 and 22. FIG.

As shown in FIG. 21(a), a model of the polarizing element 1 according to Example 1 was produced. A polarizing element 1 according to Example 1 includes a substrate 10 made of glass and a grid structure 20 made of ultraviolet curable resin (acrylic resin). The grid structure 20 has a base portion 21 provided along the surface of the substrate 10 and a plurality of ridges 22 protruding from the base portion 21 in a grid pattern. The cross-sectional shape of the protruding portion 22 is trapezoidal and tapered toward the tip 22a of the protruding portion 22 .

The reflective film 30 covering the ridges 22 of Example 1 is an Al film. The reflective film 30 is formed so as to cover the tip 22a of the ridge portion 22 and the upper portions of both side surfaces 22b. However, the reflective film 30 does not cover the lower side of both side surfaces 22 b of the protruding portion 22 and the base portion 21 . The coverage Rc of both side surfaces 22b of the ridge 22 with the reflective film 30 is 40%. In this manner, the reflective film 30 of Example 1 roundly covers the apex (upper side of the tip 22a and the side surface 22b) of the ridge 22. As shown in FIG. The surface of the reflective film 30 has a substantially elliptical shape that bulges outward and bulges in the width direction (X direction) of the ridge 22 .

As a result, the grid according to Example 1 (the structure in which the ridges 22 and the reflective film 30 are combined) has the above-described special tree shape. The maximum width W _MAX of the special tree-shaped grid (the width of the grid at the portion where the reflective film 30 bulges the most) is the width W _B of the bottom of the ridge 22 (20% above the bottom of the ridge 22). width of the protruding streak portion 22 at the height position).

The dimensions and shapes of each part of the model of the polarizing element 1 according to Example 1 are as follows.
P: 144 nm
_WT : 19 nm
_WM : 32.5 nm
W _B : 46 nm
_WMAX : 55nm
H: 220 nm
Hx: 99nm
Dt: 35 nm (maximum value)
Ds: 22.5 nm (maximum value)
RC: 40%
Rr: 60%
θ: 0° to +60°
λ: 430-680nm

After that, the model of the polarizing element 1 according to Example 1 manufactured as described above was simulated by changing the incident angle θ, and the transmission axis transmittance (Tp), the transmission axis reflectance (Ts), and the reflection axis transmission index (Rp), reflection axis reflectance (Rs), and Tp×Rs required for a polarizing beam splitter (PBS) were calculated respectively. The incident angle θ was set to 0° to +60°. As for the values of Tp, Rs, Ts, and Rp, a plurality of Tp, Ts, Rp, An average value of Rs was used. The contrast (CR) of transmitted light was also calculated by dividing the transmission axis transmittance (Tp) by the transmission axis reflectance (Ts) (CR=Tp/Ts).

The relationship between Tp, Rs, Ts, Rp, CR, Tp×Rs calculated as described above and λ is shown in the table of FIG. 21(b) and the graphs of FIGS. show. Graphs of FIGS. 22(a) to 22(c) show the relationship between Tp, Rs, Tp×Rs calculated as described above and θ.

In the table of FIG. 21(b), a plurality of wavelength bands of incident light (430 to 510 nm, 520 to 590 nm, 600 to 680 nm) and the entire wavelength band of incident light (430 to 680 nm) are divided into Average values of respective characteristic values (Tp, Rs, Ts, Rp, CR, Tp×Rs) are shown. In the graphs of FIGS. 21(c) to (d) and the graphs of FIGS. 22(a) to (c), each characteristic value (Tp, Rs, Ts, Rp , CR, Tp×Rs) are shown. In addition, in the graphs of FIGS. 22A to 22C, in order to compare with Example 1, the characteristic values (Tp(+), Tp(-), Rs(+), Rs( −), Tp×Rs(+), Tp×Rs(−)) are also shown.

As shown in FIG. 21(a), in the model of the polarizing element 1 of Example 1, the reflective film 30 covers the tops of the ridges 22 and opens the bottoms of the ridges 22, and the coverage Rc is 40%. Therefore, the grid of Example 1 (the structure in which the ridges 22 and the reflective film 30 are combined) has the above-described special tree shape. The grid having the special tree structure of Example 1 is excellent in transmissivity and polarization splitting characteristics for obliquely incident light with a large and wide range of incident angles θ.

Therefore, as shown in FIG. 21, in Example 1, Tp is 80% or more and Rs is 90% or more regardless of the wavelength λ, and high Tp and Rs can be obtained. As a result, the Tp×Rs was also 72% or more, indicating that excellent Tp×Rs characteristics can be obtained. Also, it can be seen that an excellent contrast CR of 100 or more can be obtained regardless of the wavelength λ. Therefore, it can be seen that Example 1 provides better polarization characteristics for obliquely incident light compared to Conventional Examples 1 and 2 described above.

Furthermore, as shown in FIG. 22, in Example 1, a very high Tp value of 78% or more is ensured in a wide range of the incident angle θ from 0° to 60°. As a result, a high Tp×Rs of 73% or more can be secured for oblique incident light with an incident angle θ in a large and wide range (30° to 60°), and excellent polarization separation characteristics (Tp×Rs characteristics) can be achieved. I know you have. In particular, when θ=45°, Tp is a very high value of 87%, and the value of Tp×Rs is also a very high value of 78%. Therefore, it can be seen that the polarizing element 1 of Example 1 can exhibit remarkably excellent transmittance and polarization separation characteristics for obliquely incident light at an incident angle θ of 45° and its surroundings.

Furthermore, as can be seen from the comparison results between Example 1 and Conventional Example 2 shown in FIG. 22, in Conventional Example 2, Tp and Tp×Rs decrease as the incident angle θ increases. In the range of >45°, Tp and Tp×Rs drop sharply. In contrast, in Example 1, even when θ increases, the decrease in Tp and Tp×Rs is suppressed, and high values can be maintained. In particular, when θ=45°, Example 1 can obtain Tp and Tp×Rs that are 6% or more higher than those of Conventional Example 2 when incidence is in the + direction, and Conventional Example 2 is − More than 10% higher Tp and Tp*Rs can be obtained than in the case of directional incidence. Thus, in Example 1, when θ=45°, the highest transmittance (transmittance Tp) and Tp×Rs characteristics are obtained.

Moreover, as for the reflection axis reflectance Rs, the first embodiment provides a high reflectance without significant difference compared to the conventional examples 1 and 2. FIG.

Further, with respect to the Tp×Rs characteristics required for a polarizing beam splitter (PBS), Example 1 is superior to Conventional Examples 1 and 2, and the highest Tp×Rs properties are obtained. In addition, even in the range of incident angle θ = 30° to 60°, Example 1 can obtain better characteristics than Conventional Examples 1 and 2. On the other hand, the Tp×Rs characteristics are superior to those of Conventional Examples 1 and 2. Furthermore, in Example 1, the Tp×Rs characteristics are well-balanced with respect to obliquely incident light with an incident angle θ in the range of 45°±15°. Therefore, when an image is projected using the polarizing element 1 according to Example 1 as a polarizing beam splitter, the brightness balance of the displayed image is good from the observer's point of view, and the image quality is also good. .

Thus, when the polarizing element 1 according to Example 1 is used as a polarizing beam splitter, for obliquely incident light with a large and wide range of incident angles θ from 30° to 60°, particularly obliquely incident light with an angle of 45°, Therefore, it can be seen that the P-polarized light transmittance (transmittance Tp) and the polarization separation characteristic (Tp×Rs characteristic) are remarkably excellent. Therefore, it can be said that the polarization splitting characteristics required of a polarization beam splitter can be sufficiently satisfied with respect to obliquely incident light.

Further, with respect to the transmitted light contrast CR (CR=Tp/Ts), it can be seen that in Example 1, an excellent contrast CR of 100 or more can be obtained.

(Example 2)
Next, Embodiment 2 of the present invention will be described with reference to FIG.

As shown in FIG. 23(a), a model of the polarizing element 1 according to Example 2 was produced. The model of Example 2 differs from the model of Example 1 described above in the shape of the ridges 22 and the manner of covering with the reflective film 30 . The cross-sectional shape of the ridge 22 of Example 2 is triangular and tapered toward the tip 22a of the ridge 22 .

The reflective film 30 covering the ridges 22 of Example 2 is an Al film. The reflective film 30 is formed so as to cover the tip 22a of the ridge portion 22 and the upper portions of both side surfaces 22b. However, the reflective film 30 does not cover the lower side of both side surfaces 22 b of the protruding portion 22 and the base portion 21 . The coverage Rc of both side surfaces 22b of the ridge 22 with the reflective film 30 is 45%. In this manner, the reflective film 30 of Example 2 roundly covers the apex of the ridge 22 (upper side of the tip 22a and the side surface 22b). The surface of the reflective film 30 has a substantially elliptical shape that bulges outward and bulges in the width direction (X direction) of the ridge 22 . As described above, the grid according to the second embodiment (the structure in which the ridges 22 and the reflective film 30 are combined) has the above-described special tree shape, as in the first embodiment.

The dimensions and shapes of each part of the model of the polarizing element 1 according to Example 2 are as follows.
P: 140 nm
_WT : 10 nm
_WB : 40 nm
_WMAX : 41 nm
H: 230 nm
Hx: 103.5 nm
Dt: 50 nm (maximum value)
Ds: 17 nm (maximum value)
RC: 45%
Rr: 55%
θ: 0° to +60°
λ: 430-680nm

After that, the model of the polarizing element 1 according to Example 2 manufactured as described above is simulated by changing the incident angle θ, and the transmission axis transmittance (Tp), the reflection axis reflectance (Rs), and the polarized beam Tp×Rs required for the splitter (PBS) was calculated. As the values of Tp and Rs, the wavelength λ of the incident light was changed in the range of 430 to 680 nm, and the average value of a plurality of Tp and Rs values calculated for the incident light of each wavelength was used. . The relationships between Tp, Rs, Tp×Rs calculated as described above and θ are shown in graphs of FIGS. 23(b) to (d).

As shown in FIG. 23(a), the grid of Example 2 (the structure in which the ridges 22 and the reflective film 30 are combined) has the above-described special tree shape, similar to Example 1. Therefore, it is excellent in transmittance and polarization separation characteristics for obliquely incident light with an incident angle θ in a large and wide range.

Therefore, as shown in FIG. 23, in Example 2, a high value Tp of 74% or more is ensured in a wide range of the incident angle θ from 0° to 45°. In particular, when θ = 30° and 45°, a high Tp of 88% or more can be secured, a high Tp x Rs of 74% or more can be secured, and excellent polarization separation characteristics (Tp x Rs characteristics) can be obtained. I understand. Therefore, it can be seen that the polarizing element 1 of Example 2 can exhibit remarkably excellent transmittance and polarization separation characteristics for obliquely incident light with an incident angle θ of 30° to 45°.

As in Example 2 described above, even when the shape of the ridges 22 of the grid structure 20 is different from that in Example 1, better transmittance and polarization separation characteristics can be obtained than in Conventional Examples 1 to 3. I understand. However, when the incident angle θ is 60°, Example 1 is superior to Example 2 in Tp and Tp×Rs characteristics.

(Example 3)
Next, a third embodiment of the present invention will be described with reference to FIG. In Example 3, the relationship between the height H of the ridges 22 and the polarization characteristics of the polarizing element 1 was verified.

As shown in FIG. 24(a), a model of the polarizing element 1 according to Example 3 was produced. The model of Example 3 is similar to the model of Example 1 above. The cross-sectional shape of the protruding portion 22 is trapezoidal and tapered toward the tip 22a of the protruding portion 22 . The grid of Example 3 (the structure in which the ridges 22 and the reflective film 30 are combined) has the above-described special tree shape, as in Example 1. FIG. In Example 3, while maintaining the coverage Rc at 45%, the height H of the ridges 22 was varied stepwise within the range of 100 to 220 nm.

The dimensions and shapes of each part of the model of the polarizing element 1 according to Example 3 are as follows.
P: 144 nm
_WT : 19 nm
_WM : 32.5 nm
W _B : 46 nm
_WMAX : 55nm
H: 100-220 nm
Hx: 45-99 nm
Dt: 35 nm (maximum value)
Ds: 22.5 nm (maximum value)
RC: 45%
Rr: 55%
θ: +45°
λ: 430-680nm

After that, the model of the polarizing element 1 according to Example 3 manufactured as described above was simulated by changing the height H of the protruding portion 22, and Tp, Rs, and Tp×Rs were calculated. The incident angle θ was +45°. As the values of Tp and Rs, the wavelength λ of the incident light is varied in the range of 430 to 680 nm, and the average value of multiple values of Tp and Rs calculated for the incident light of each wavelength λ is used. board. The transmitted light contrast CR was also calculated by dividing Tp by Ts.

The relationships between Tp, Rs, Tp×Rs, CR calculated as described above and H are shown in graphs of FIGS. 24(b) to (e).

As shown in FIG. 24, in order to improve the various characteristics (Tp, Tp×Rs, CR) of the polarizing element 1 for 45° oblique incident light, the height H of the ridges 22 should be 160 nm or more. , more preferably 180 nm or more, and particularly preferably 220 nm or more.

Specifically, regarding Tp, as shown in FIG. 24(b), if H is 160 nm or more, Tp is 80% or more and high transmittance can be obtained, which is preferable. Furthermore, if H is 180 nm or more, Tp of 85% or more can be obtained, which is more preferable. In addition, if H is 220 nm or more, Tp of 87% or more can be obtained, which is particularly preferable.

As for the Tp×Rs characteristics, as shown in FIG. 24(d), if H is 160 nm or more, excellent Tp×Rs of 70% or more can be obtained, which is preferable. Furthermore, if H is 180 nm or more, Tp×Rs of 75% or more can be obtained, which is more preferable. In addition, if H is 220 nm or more, Tp×Rs of 77% or more can be obtained, which is particularly preferable.

As for the contrast CR, as shown in FIG. 24(e), it suffices if H is 100 nm or more, whereby a CR of 40 or more is obtained. If H is 160 nm or more, an excellent CR of 150 or more can be obtained, which is preferable. Furthermore, if H is 180 nm or more, an excellent CR of 250 or more can be obtained, which is more preferable. In addition, if H is 220 nm or more, an excellent CR of 500 or more can be obtained, which is particularly preferred.

(Example 4)
Next, a fourth embodiment of the present invention will be described with reference to FIG. In Example 4, the relationship between the thickness Dt of the reflective film 30 covering the tip 22a of the ridge portion 22 (tip thickness Dt of the reflective film 30) and the polarization characteristics of the polarizing element 1 was verified.

As shown in FIG. 25(a), a model of the polarizing element 1 according to Example 4 was produced. The model of Example 4 is similar to the model of Example 1 above. The cross-sectional shape of the protruding portion 22 is trapezoidal and tapered toward the tip 22a of the protruding portion 22 . The grid of Example 4 (the structure in which the ridges 22 and the reflective film 30 are combined) has the above-described special tree shape, as in Example 1. FIG. In Example 4, the tip thickness Dt of the reflective film 30 was changed stepwise within the range of 5 to 35 nm.

The dimensions and shapes of each part of the model of the polarizing element 1 according to Example 4 are as follows.
P: 144 nm
_WT : 19 nm
_WM : 32.5 nm
W _B : 46 nm
_WMAX : 55nm
H: 220 nm
Hx: 99 nm
Dt: 5 to 35 nm (maximum value)
Ds: 22.5 nm (maximum value)
RC: 45%
Rr: 55%
θ: +45°
λ: 430-680nm

After that, simulations were performed by changing the tip thickness Dt of the reflective film 30 for the model of the polarizing element 1 according to Example 4 manufactured as described above, and Tp, Rs, Tp×Rs, and CR were calculated. The incident angle θ was +45°. The relationships between Tp, Rs, Tp×Rs, CR calculated as described above and Dt are shown in the graphs of FIGS. 25(b) to (e).

As shown in FIG. 25, in order to improve various characteristics (Tp, Tp×Rs, CR) of the polarizing element 1 with respect to 45° oblique incident light, the tip thickness Dt of the reflective film 30 should be 5 nm or more. , and more preferably 15 nm or more.

Specifically, regarding Tp, as shown in FIG. 25(b), if Dt is 5 nm or more, Tp is 85% or more, and high transmittance can be obtained, which is preferable. As for Rs, as shown in FIG. 25(c), if Dt is 5 nm or more, Rs is 85% or more and a high reflectance can be obtained, which is preferable.

As for the Tp×Rs characteristics, as shown in FIG. 25(d), if Dt is 15 nm or more, excellent Tp×Rs of 78% or more can be obtained, which is more preferable.

As for the contrast CR, as shown in FIG. 25E, if Dt is 5 nm or more, an excellent CR of 100 or more can be obtained, which is preferable. Furthermore, if Dt is 15 nm or more, an excellent CR of 250 or more can be obtained, which is more preferable.

(Example 5)
Next, a fifth embodiment of the present invention will be described with reference to FIG. In Example 5, the relationship between the thickness Ds of the reflective film 30 covering the side surface 22b of the ridge portion 22 (side surface thickness Ds of the reflective film 30) and the polarization characteristics of the polarizing element 1 was verified.

As shown in FIG. 26(a), a model of the polarizing element 1 according to Example 5 was produced. The model of Example 5 is similar to the model of Example 1 above. The cross-sectional shape of the protruding portion 22 is trapezoidal and tapered toward the tip 22a of the protruding portion 22 . The grid of Example 5 (the structure in which the ridges 22 and the reflective film 30 are combined) has the above-described special tree shape, as in Example 1. FIG. In Example 5, the side thickness Ds of the reflective film 30 was changed stepwise within the range of 5 to 35 nm.

The dimensions and shapes of each part of the model of the polarizing element 1 according to Example 5 are as follows.
P: 144 nm
_WT : 19 nm
_WM : 32.5 nm
W _B : 46 nm
W _MAX : 20~80nm
H: 220 nm
Hx: 99 nm
Dt: 35 nm (maximum value)
Ds: 5 to 35 nm (maximum value)
RC: 45%
Rr: 55%
θ: +45°
λ: 430-680nm

After that, simulations were performed by changing the side thickness Ds of the reflective film 30 for the model of the polarizing element 1 according to Example 5 manufactured as described above, and Tp, Rs, Tp×Rs, and CR were calculated respectively. The incident angle θ was +45°. The relationships between Tp, Rs, Tp×Rs, CR calculated as described above and Dt are shown in the graphs of FIGS. 26(b) to (e).

As shown in FIG. 26, in order to improve various characteristics (Tp, Tp×Rs, CR) of the polarizing element 1 with respect to oblique incident light of 45°, the side thickness Ds of the reflective film 30 should be 10 nm or more. , 30 nm or less, more preferably 12.5 nm or more and 25 nm or less, and particularly preferably 15 nm or more and 25 nm or less.

Specifically, regarding Tp, as shown in FIG. 26B, when Ds is 10 nm or more and 30 nm or less, Tp is 80% or more, and high transmittance can be obtained, which is preferable. Furthermore, when Ds is 12.5 nm or more and 25 nm or less, Tp is 85% or more, and higher transmittance can be obtained, which is more preferable. Furthermore, when Ds is 15 nm or more and 20 nm or less, Tp is 87% or more, and a higher transmittance can be obtained, which is particularly preferable.

As for Rs, as shown in FIG. 26(c), if Ds is 10 nm or more, Rs is 80% or more, and a high reflectance can be obtained, which is preferable. Furthermore, when Ds is 12.5 nm or more, Rs is 85% or more, and a higher reflectance can be obtained, which is more preferable. Furthermore, when Ds is 15 nm or more, Rs is 87% or more, and a higher reflectance can be obtained, which is particularly preferable.

As for the Tp×Rs characteristics, as shown in FIG. 26(d), when Ds is 12.5 nm or more and 30 nm or less, excellent Tp×Rs of 70% or more can be obtained, which is preferable. Furthermore, when Ds is 15 nm or more and 25 nm or less, an excellent Tp×Rs of 76% or more can be obtained, which is more preferable.

As for the contrast CR, as shown in FIG. 26(e), Ds may be 10 nm or more, but if Ds is 12.5 nm or more, an excellent CR of 50 or more can be obtained, which is preferable. Furthermore, if Ds is 15 nm or more, an excellent CR of 100 or more can be obtained, which is more preferable.

(Example 6)
Next, a sixth embodiment of the present invention will be described with reference to FIG. In Example 6, the relationship between the coverage Rc of the side surface 22b of the projection 22 with the reflecting film 30 and the polarization characteristics of the polarizing element 1 was verified.

As shown in FIG. 27(a), a model of the polarizing element 1 according to Example 6 was produced. The model of Example 6 is similar to the model of Example 1 above. The cross-sectional shape of the protruding portion 22 is trapezoidal and tapered toward the tip 22a of the protruding portion 22 . The grid of Example 6 (the structure in which the ridges 22 and the reflective film 30 are combined) has the above-described special tree shape, as in Example 1. FIG. In Example 6, by changing the height Hx of the range in which the side surface 22b of the protruding portion 22 is covered with the reflective film 30, the coverage Rc was changed stepwise within the range of 20 to 90%.

The dimensions and shapes of each part of the model of the polarizing element 1 according to Example 6 are as follows.
P: 144 nm
_WT : 19 nm
_WM : 32.5 nm
W _B : 46 nm
_WMAX : 55nm
H: 220 nm
Hx: 44-198 nm
Dt: 35 nm (maximum value)
Ds: 22.5 nm (maximum value)
Rc: 20-90%
Rr: 80-10%
θ: +45°
λ: 430-680nm

After that, simulations were performed by changing the coverage ratio Rc for the model of the polarizing element 1 according to Example 6 produced as described above, and Tp, Rs, Tp×Rs, and CR were calculated, respectively. The incident angle θ was +45°. The relationships between Tp, Rs, Tp×Rs, CR calculated as described above and Dt are shown in the graphs of FIGS. 27(b) to (e).

As shown in FIG. 27, in order to improve various characteristics (Tp, Tp×Rs, CR) of the polarizing element 1 with respect to 45° oblique incident light, the coverage Rc is 25% or more and 80% or less. is preferably 30% or more and 70% or less, more preferably 30% or more and 60% or less, and particularly preferably 40% or more and 50% or less. .

Specifically, regarding Tp, as shown in FIG. 27B, when Rc is 25% or more and 80% or less, Tp is 75% or more and high transmittance can be obtained, which is preferable. Furthermore, when Rc is 30% or more and 70% or less, Tp is 80% or more, and higher transmittance can be obtained, which is more preferable. Furthermore, when Rc is 40% or more and 50% or less, Tp is 85% or more, and a higher transmittance can be obtained, which is particularly preferable.

As for Rs, as shown in FIG. 27(c), if Rc is 20% or more, Rs is 85% or more, and a high reflectance can be obtained, which is preferable.

As for the Tp×Rs characteristics, as shown in FIG. 27(d), when Rc is 25% or more and 80% or less, Tp×Rs is 70% or more, and excellent Tp×Rs characteristics are obtained. preferred because Furthermore, when Rc is 30% or more and 70% or less, Tp × Rs is 72% or more, and when Rc is 30% or more and 60% or less, Tp × Rs is 75% or more, which is more excellent. Tp×Rs characteristics are obtained, which is more preferable. Furthermore, when Rc is 40% or more and 50% or less, Tp×Rs is 77% or more, and more excellent Tp×Rs characteristics can be obtained, which is particularly preferable.

As for the contrast CR, as shown in FIG. 27(e), Rc should be 20% or more, but if Rc is 30% or more, an excellent CR of 100 or more can be obtained, which is preferable. Furthermore, if the Rc is 40% or more, an excellent CR of 200 or more can be obtained, which is more preferable.

(Example 7)
Next, a seventh embodiment of the present invention will be described with reference to FIG. In Example 7, the relationship between the thickness Ds of the reflective film 30 covering the side surface 22b of the ridge portion 22 (the side surface thickness Ds of the reflective film 30), the incident angle θ, and the polarization characteristics of the polarizing element 1 was verified. .

As shown in FIG. 28(a), a model of the polarizing element 1 according to Example 7 was produced. The model of Example 7 is similar to the model of Example 1 above. The cross-sectional shape of the protruding portion 22 is trapezoidal and tapered toward the tip 22a of the protruding portion 22 . The grid of Example 7 (the structure in which the ridges 22 and the reflective film 30 are combined) has the above-described special tree shape, as in Example 1. FIG. In Example 7, the side thickness Ds of the reflective film 30 was changed stepwise in the range of 17.5 to 25 nm, and the incident angle θ was changed stepwise in the range of 0 to 60°.

The dimensions and shapes of each part of the model of the polarizing element 1 according to Example 7 are as follows.
P: 144 nm
_WT : 19 nm
_WM : 32.5 nm
W _B : 46 nm
_WMAX : 45nm, 55nm, 60nm
H: 220 nm
Hx: 99 nm
Dt: 35 nm (maximum value)
Ds: 17.5 nm, 22.5 nm, 25 nm (maximum)
RC: 45%
Rr: 55%
θ: 0 to +60°
λ: 430-680nm

After that, the model of the polarizing element 1 according to Example 7 manufactured as described above is simulated by changing the side thickness Ds of the reflective film 30 and the incident angle θ, and Tp, Rs, and Tp×Rs are calculated respectively. bottom. The incident angle θ was changed in steps of 15° in the range of 0 to +60°. The relationships between Tp, Rs, Tp×Rs calculated as described above and Dt are shown in graphs of FIGS. 28(b) to (d).

As shown in FIG. 28, even when the side thickness Ds of the reflective film 30 is changed stepwise in the range of 17.5 to 25 nm, the oblique incident light with a wide range of incident angles θ from 0° to +60° Therefore, it can be seen that the polarizing element 1 has good polarizing characteristics (Tp, Rs, Tp×Rs). In particular, it can be seen that extremely excellent polarization characteristics are exhibited for obliquely incident light with an incident angle θ of +45°.

Specifically, with regard to Tp, as shown in FIG. 28(b), even if Ds varies in the range of 17.5 to 25 nm, if θ is in the range of +30° to +60°, Tp is 75°. % or more, and a high transmittance can be obtained, which is preferable. Furthermore, when θ is +45°, Tp is 85% or more, and the highest transmittance can be obtained, which is more preferable.

As for Rs, as shown in FIG. 28(c), Rs is 85% or more in a wide range of incident angles θ from 0° to +60°, and high reflectance is obtained, which is preferable.

As for the Tp×Rs characteristics, as shown in FIG. 28(d), even if Ds changes in the range of 17.5 to 25 nm, Tp×Rs becomes 70% or more, and excellent Tp×Rs characteristics are obtained, which is preferable. Furthermore, when θ is +45°, Tp×Rs becomes 76% or more, and the best Tp×Rs characteristics can be obtained, which is more preferable. Also, the Tp×Rs characteristics are well-balanced with respect to obliquely incident light with an incident angle θ in the range of 45°±15°. Therefore, when an image is projected using the polarizing element 1 according to Example 7 as a polarizing beam splitter, the brightness balance of the displayed image is good from the observer's point of view, and the image quality is also good. .

(Example 8)
Next, an eighth embodiment of the present invention will be described with reference to FIG. In Example 8, the relationship between the maldistribution ratio when the reflective film 30 covering the protruding portion 22 is maldistributed on one side and the polarization characteristics of the polarizing element 1 was verified.

As shown in FIG. 29(a), a model of the polarizing element 1 according to Example 8 was produced. The model of Example 8 is the same as the model of Example 1 above, except that the reflective film 30 is unevenly distributed on one side of the ridge 22 . The cross-sectional shape of the protruding portion 22 is trapezoidal and tapered toward the tip 22a of the protruding portion 22 . The grid of Example 8 (the structure in which the ridges 22 and the reflective film 30 are combined) has the above-described special tree shape, as in Example 1. FIG.

In Example 8, regarding the left side surface 22b of the ridge 22, the side thickness Ds (left side) of the reflective film 30 covering the side surface 22b was fixed at 22.5 nm, and the coverage height Hx (left side) was fixed at 22.5 nm. was fixed at 99 nm and the coverage Rc (left) was fixed at 45%. On the other hand, the side thickness Ds (right side) of the reflective film 30 covering the right side surface 22b of the ridge 22 was changed stepwise within the range of 0 to 22.5 nm. In accordance with this, with respect to the right side surface 22b of the ridge 22, the height Hx (right side) of the coverage range of the right side surface 22b is changed stepwise in the range of 0 to 99 nm, and the coverage rate Rc (right side ) was changed stepwise in the range of 0 to 45%. As a result, the grid maximum width W _MAX varied stepwise within the range of 32.5 to 55 nm.

In the eighth embodiment, the incident angle θ is an incident angle (θ=0° to +60°) in the + direction that is incident obliquely on the left side of the ridge 22, and On the other hand, two directions of incident angle (θ=0° to −60°) in the − direction where the light is incident obliquely were used.

The dimensions and shapes of each part of the model of the polarizing element 1 according to Example 8 are as follows.
P: 144 nm
_WT : 19 nm
_WM : 32.5 nm
W _B : 46 nm
_WMAX : 32.5nm, 37.5nm, 47.5nm, 55nm
H: 220 nm
Hx (left side): 99 nm
Hx (right side): 0-99 nm
Dt: 35 nm (maximum value)
Ds (left side): 22.5 nm (maximum value)
Ds (right side): 0 nm, 5 nm, 10 nm, 22.5 nm (maximum)
Rc (left side): 45%
Rc (right side): 0%, 22%, 33%, 45%,
Rr (left side): 55%
Rc (right side): 100%, 78%, 67%, 55%
θ (left side): 0 to +60°
θ (right side): 0 to -60°
λ: 430-680nm

After that, the model of the polarizing element 1 according to Example 8 produced as described above is simulated by changing Ds (right side) and Rc (right side) regarding the left side surface 22b of the reflective film 30, Tp, Rs, Tp×Rs and CR were calculated respectively. The incident angle θ was changed in steps of 15° in the range of 0 to +60°. The relationships between Tp, Rs, Tp×Rs, CR calculated as described above and Dt are shown in graphs of FIGS. 29(b) to (e).

As shown in FIG. 29, even when the reflective film 30 is unevenly distributed on one side of the ridge 22, that is, even when the grid is left-right asymmetric, the polarizing element 1 exhibits good polarization characteristics (Tp, Rs , Tp×Rs, CR).

Specifically, regarding Tp, as shown in FIG. However, both Tp(+) and Tp(-) were 85% or more, and high transmittance was obtained on both sides of the grid. In this case, the difference between Tp(+) and Tp(-) is 3% or less, and it is confirmed that there is no significant difference between Tp(+) and Tp(-) depending on the direction of oblique incident light. was done.

Also, regarding Rs, as shown in FIG. Both Rs(+) and Rs(-) were above 85%, resulting in high reflectivity on both sides of the grid.

Also, regarding the Tp×Rs characteristics, as shown in FIG. However, Tp×Rs was 75% or more, and excellent Tp×Rs characteristics were obtained.

Also, regarding contrast CR, as shown in FIG. , an excellent CR was obtained. Furthermore, it is preferable that the Ds (right side) is 5 nm or more and the coverage (left side) is 22% or more, thereby obtaining an excellent CR of 100 or more. In addition, it is more preferable that the Ds (right side) is 10 nm or more and the coverage (left side) is 33% or more, resulting in a better CR of 150 or more.

(Verification results of the shape of the reflective film: Example 9, Conventional example 4)
Next, with reference to FIGS. 30 and 31, the ninth embodiment of the present invention (the reflective film 30 is round) and the conventional example 4 (the reflective film 30 is square) are compared. A result of verifying the relationship between the shape of the reflective film 30 and the polarization characteristics of the polarizing element 1 will be described.

As shown in FIGS. 30 and 31, a model of the polarizing element 1 according to Example 9 and a model of the polarizing element 1 according to Conventional Example 4 were produced.

The model of the polarizing element 1 according to Example 9 has a special tree shape, like the model of Example 1 described above (see FIG. 21, etc.). The grid of the polarizing element 1 according to Example 9 covers the base portion 21, the ridges 22 having a trapezoidal cross section, and the tops of the ridges 22 (tops of the tips 22a and side surfaces 22b). and a reflective film 30 . However, the model of the polarizing element 1 according to Example 9 differs from the model of Example 1 described above in the coverage Rc of both side surfaces 22b of the ridge portion 22 by the reflective film 30. The coverage Rc of 9 is 45%. The reflective film 30 of Example 9 has a shape that wraps around the apex of the ridge 22 . The surface of the reflective film 30 according to the ninth embodiment has a substantially elliptical shape with roundness that bulges outward, and bulges in the width direction (X direction) of the ridge portion 22 . The surface of the reflective film 30 of the ninth embodiment has a round, smoothly curved surface shape, and does not have sharp corners or steps. The reflective film 30 of Example 9 is hereinafter referred to as a round reflective film.

On the other hand, the model of the polarizing element 1 according to Conventional Example 4 differs from the model of Example 9 in the shape of the reflective film 30 . The reflective film 30 of Conventional Example 4 has a rectangular shape, and has two angular corners at both left and right ends of the top of the reflective film 30. The reflective film 30 of the above-described reflective film 30 is rounded. It is different from the swollen shape (round reflective film). Below, the reflective film 30 of Comparative Example 4 is referred to as a rectangular reflective film. The model of the polarizing element 1 of Conventional Example 4 corresponds to the wire grid polarizer disclosed in Patent Document 7 mentioned above.

As described above, Conventional Example 4 differs from Example 9 in the shape of the reflective film 30, but other requirements are the same as those of Example 9.

The dimensions of each part common to the models of the polarizing element 1 of Example 9 and Conventional Example 4 are as follows.
P: 144 nm
_WT : 19 nm
_WM : 32.5 nm
W _B : 46 nm
_WMAX : 55nm
H: 220 nm
Hx: 99nm
Dt: 35 nm (maximum value)
Ds: 22.5 nm (maximum value)
RC: 45%
Rr: 55%
θ: 0° to +60°
λ: 430-680nm

For the models of the polarizing element 1 according to Example 9 and Conventional Example 4 fabricated as described above, simulations were performed by changing the incident angle θ, and Tp, Rs, and Tp×Rs were calculated. The incident angle θ was set to 0° to +60°.

The relationships between Tp, Rs, Tp×Rs calculated as described above and θ are shown in the graphs of FIGS. 30(b) to (d).

As shown in FIG. 30, in Example 9, a very high value Tp of 78% or more is ensured in a wide range of the incident angle θ from 0° to 60°. As a result, a high Tp×Rs of 73% or more can be secured for oblique incident light with an incident angle θ in a large and wide range (30° to 60°), and excellent polarization separation characteristics (Tp×Rs characteristics) can be achieved. I know you have. In particular, when θ=45°, Tp is a very high value of 87%, and the value of Tp×Rs is also a very high value of 78%. Therefore, it can be seen that the polarizing element 1 of Example 9 can exhibit remarkably excellent transmittance and polarization separation characteristics for obliquely incident light at an incident angle θ of 45° and its surroundings.

Furthermore, as can be seen from the comparison results between Example 9 and Conventional Example 4 shown in FIG. In particular, in the range of θ>45°, Tp and Tp×Rs drop sharply.

On the other hand, in Example 9, in the range of 0° ≤ θ ≤ 45°, Tp and Tp × Rs rather increased as θ increased, and high values of Tp and Tp × Rs could be maintained. there is Furthermore, in Example 9, in the range of 45°<θ≦60°, even if θ increases, the degree of decrease in Tp and Tp×Rs is significantly suppressed compared to Conventional Example 4, and Tp and a high value of Tp×Rs can be maintained. In particular, when θ=45°, Example 9 can obtain Tp and Tp×Rs that are 5% or more higher than those of Conventional Example 4. FIG. Further, when θ=60°, Example 9 can obtain Tp and Tp×Rs that are 7% or more higher than those of Conventional Example 4. FIG. Thus, in Example 9, in a large and wide range of incident angles θ (30° to 60°, particularly 45° to 60°), remarkably excellent transmittance (transmittance Tp) and Tp × Rs characteristics is obtained.

As for Rs, in Example 9, compared with Conventional Example 4, a high reflectance with no significant difference is obtained.

Further, with respect to the Tp×Rs characteristics required for a polarizing beam splitter (PBS), Example 9 is superior to Conventional Example 4, and the highest Tp×Rs characteristics are obtained when the incident angle θ=45°. can get. Further, even in the range of incident angle θ = 30° to 60°, Example 9 can obtain better characteristics than Conventional Example 4. , the Tp×Rs characteristics are superior to those of Conventional Example 4. Furthermore, in Example 9, the Tp×Rs characteristics are well-balanced with respect to obliquely incident light with an incident angle θ in the range of 45°±15°. Therefore, when an image is projected using the polarizing element 1 according to Example 9 as a polarizing beam splitter, the brightness balance of the displayed image is good from the observer's point of view, and the image quality is also good. .

As described above, when the polarizing element 1 is used as a polarizing beam splitter, the 9th embodiment has a large and wide range of incident angles θ from 30° to 60° compared to the conventional example 4, especially 45°. It can be seen that the P-polarized light transmittance (transmittance Tp) and the polarization splitting characteristic (Tp×Rs characteristic) are remarkably excellent with respect to obliquely incident light of 100°. Therefore, it can be said that the polarization splitting characteristics required of a polarization beam splitter can be sufficiently satisfied with respect to obliquely incident light.

As described above, the ninth embodiment having the round reflective film 30 has a lower dependence on the incident angle θ of the oblique incident light than the conventional example 4 having the rectangular reflective film 30 . Excellent transmittance and polarization separation characteristics (Tp×Rs characteristics) as a polarization beam splitter. The reason for this will be described below with reference to FIG.

As shown in FIG. 31, the transmittance of incident light in the wire grid polarizer 1 is basically determined by the ratio (W _G /W _A ) of the effective grid width W _A to the gap width W _G . The grid width _WA is the width of one reflective film 30 in the direction perpendicular to the direction of travel of incident light, and the gap width _WG is the width of two adjacent reflective films 30 in the direction perpendicular to the direction of travel of incident light. It is the width of the gap between the two reflective films 30 . The smaller the width of the reflective film 30 (the width of the metal grid portion) in one pitch of the grid structure 20, the less the incident light reflected by the reflective film 30 with the smaller width, and the greater the transmittance of the incident light.

Here, as shown in FIG. 31, consider the case where the incident light is incident on the polarizing element 1 from an oblique direction (that is, when θ>0°). In this case, in Example 9 in which the reflective film 30 is round, the effective grid width _WA when viewed obliquely is smaller than in Conventional Example 4 in which the reflective film 30 is square. The apparent gap width _WG increases. Therefore, when oblique incident light is incident on the polarizing element 1, the transmittance Tp of the ninth embodiment is higher than the transmittance Tp of the fourth conventional example. As a result, the Tp×Rs characteristics of Example 9 are superior to those of Conventional Example 4. For example, when the incident angle θ of obliquely incident light is 45°, the transmittances Tp and Tp×Rs of Example 9 are each about 5% higher than those of Conventional Example 4. It can be seen that the transmittances Tp and Tp×Rs of Example 9 are each about 7% higher than those of Conventional Example 4 (see FIGS. 30(b) and 30(d)).

For the reasons described above, the ninth embodiment having the round reflective film 30 has a lower dependence on the incident angle θ of the oblique incident light than the conventional example 4 having the rectangular reflective film 30, and the It can be said to be excellent in transparency and polarization separation characteristics (Tp×Rs characteristics) as a polarization beam splitter.

(Verification result of heat dissipation)
Next, a hybrid wire grid polarizing element 1 made of an inorganic material and an organic material according to an example of the present invention and a film type wire grid polarizing element made of an organic material according to a conventional example are compared. I will explain the result of verifying the heat dissipation of.

As described above, according to the wire grid polarizing element 1 according to the present embodiment, the substrate 10 is made of an inorganic material such as glass that has excellent heat resistance. Furthermore, the base portion 21 and the plurality of ridges 22 of the grid structure 20 provided on the substrate 10 are integrally formed of a heat-resistant organic material. Thus, the wire grid polarizing element 1 according to this embodiment is a hybrid polarizing element that combines organic and inorganic materials. Therefore, the thermal resistance R [m ² ·K/W] of the entire polarizing element 1 is small, and heat can be efficiently released from the grid structure 20 to the substrate 10, so it is considered to be excellent in heat dissipation.

On the other hand, the conventional film-type wire grid polarizing element is mainly made of an organic material, and thus has low heat resistance (about 100° C.). Moreover, since the total thickness of the organic material layer composed of the substrate (base film), double-sided tape (OCA), and grid structure is increased, the thermal resistance R of the organic material layer is also considered to be increased.

Therefore, the hybrid-type wire grid polarizing element 1 according to the present embodiment has excellent heat resistance and heat dissipation compared to conventional film-type polarizing elements (heat resistance: about 100 ° C.) made of organic materials. For example, it has heat resistance in a high temperature environment up to about 200°C. Therefore, it is considered that the hybrid wire grid polarizer 1 according to the present embodiment can exhibit excellent heat dissipation characteristics while realizing excellent polarization characteristics.

Therefore, an embodiment of the hybrid type wire grid polarizing element of the present invention and a conventional film type wire grid polarizing element were actually produced, and their thermal resistance R and heat dissipation properties were verified.

Table 1 shows the types of general substrate materials and their thermal conductivity λ [W/m·K]. Table 2 shows the thickness of each layer made of organic material (PMMA) and the thickness of organic material (PMMA) for the hybrid type wire grid polarizing element 1 according to the example of the present invention and the film type wire grid polarizing element according to the conventional example. ) (total thickness D _ALL ) and thermal resistance R [m ² ·K/W].

As shown in Table 2, in the hybrid-type polarizing element 1 according to the example, the base portion 21 and the ridges 22 constituting the grid structure 20 are made of an organic material, and the substrate is made of an inorganic material. . On the other hand, in the conventional film-type polarizing element, the substrate, the base portion forming the grid structure, and the double-sided tape for bonding the base portion and the substrate are all made of organic materials. Here, PMMA (Poly Methyl Methylate) was used as the organic material. As a result, the total thickness D _ALL of the PMMA material of the hybrid polarizing element 1 according to the example is 30200 [nm]. On the other hand, the total thickness D _ALL of the PMMA material of the film-type polarizing element according to the conventional example is 255000 [nm], which is significantly larger than the D _ALL of the example.

As shown in Table 1, the thermal conductivity λ of PMMA is 0.21 [W/m·K]. The thermal resistance R is obtained by dividing the "material thickness D _ALL " by the "thermal conductivity λ" (R=D _ALL /λ). Therefore, the thermal resistance R of the grid structure 20 of the hybrid polarizing element 1 according to the example is 0.000144 [m ² ·K/W]. On the other hand, the thermal resistance R of the conventional film-type polarizing element is 0.001214 [m ² ·K/W].

Therefore, by using the hybrid-type polarizing element 1 according to the embodiment of the present invention, the value of the thermal resistance R of the grid structure 20 made of PMMA material can be reduced to about It can be reduced to 1/8.4. Therefore, according to the hybrid polarizing element 1 according to the embodiment of the present invention, the heat of the grid structure 20 made of an organic material (for example, PMMA) is transferred from an inorganic material that is superior in heat resistance and heat dissipation to an inorganic material. Through the substrate 10, the heat can be efficiently released to the outside and the heat can be dissipated. Therefore, the hybrid-type polarizing element 1 according to the embodiment of the present invention has extremely excellent heat resistance and heat dissipation compared to the conventional example.

Although PMMA was used as the material of the grid structure 20 in the above embodiment, it is not limited to such an example, and various organic materials other than PMMA may be used as the material of the grid structure of the present invention. .

Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention belongs can conceive of various modifications or modifications within the scope of the technical idea described in the claims. It is understood that these also naturally belong to the technical scope of the present invention.

According to the present embodiment, a polarizing element that has good polarizing properties, does not cause deterioration in heat dissipation and manufacturing costs, and has excellent transmittance for light with a wide range of incident angles, and a method for manufacturing the polarizing element. can be provided. Further, according to this embodiment, it is possible to provide a projection display device having excellent polarization characteristics and heat resistance, and a vehicle equipped with the projection display device.

REFERENCE SIGNS LIST 1 wire grid polarizing element 2 light source 3 display element 4 reflector 5 display surface 6 cover portion 10 substrate 20 grid structure 21 base portion 22 ridge portion 23 grid structure material 24 concave portion 30 reflective film 40 protective film 50 heat dissipation member 60 master disc 61 Base material for master 62 Metal film for master 63 Protrusion 64 Release film coat 65 Groove 70 Resist mask 80 Metal film 100 Head-up display device 200 Projection display device 210 Light source 220 PS converter 230 Polarizing beam splitter 240 Reflective liquid crystal display Element 250 Lens 260 Light absorber TS Substrate thickness TB Base thickness P Pitch of ridge H Height of ridge Hx Height range in which the reflective film covers the side surface of the ridge Ds Side of reflective film Thickness Dt Tip thickness of the reflective film W _MAX Maximum width of the reflective film that covers the ridges (maximum grid width)
_WB Width of the bottom of the ridge (grid bottom width)
W _Width of the top of the ridge (width of the top of the ridge)
W _A effective grid width W _G gap width

Claims (19)

A hybrid wire grid polarizing element made of an inorganic material and an organic material,
a substrate made of the inorganic material;
a grid structure made of the organic material and integrally formed with a base provided on the substrate and a plurality of ridges protruding from the base;
a functional film made of a metal material and covering a part of the ridge;
with
The protruding portion has a tapered shape in which the width becomes narrower as the distance from the base portion increases,
The functional film covers the tip of the ridge and the upper side of at least one side surface, and does not cover the lower sides of both side surfaces of the ridge and the base portion,
The surface of the functional film covering the ridge is rounded and bulges in the width direction of the ridge, and the maximum width (W _MAX ) of the functional film covering the ridge is , the width (W _B ) of the ridge portion of the portion not covered with the functional film at a position 20% above the height of the ridge portion from the bottom of the ridge portion ;
The coverage ratio (Rc) of the side surface of the ridge portion with the functional film is the height of the portion of the side surface of the ridge portion covered with the functional film ( Hx), when
The wire grid polarizing element , wherein the coverage (Rc) is 30% or more and 70% or less . 2. The product (Tp×Rs) of the transmission axis transmittance (Tp) and the reflection axis reflectance (Rs) of incident light at an incident angle of 45° with respect to the wire grid polarizing element is 70% or more . The wire grid polarizing element according to . 3. The wire grid polarization element according to claim 1, wherein the height (H) of said ridges is 160 nm or more. The wire grid polarization element according to any one of claims 1 to 3 , wherein the thickness (Dt) of the functional film covering the tips of the ridges is 5 nm or more. The wire grid polarization element according to any one of claims 1 to 4 , wherein the thickness (Ds) of the functional film covering the side surfaces of the ridges is 10 nm or more and 30 nm or less. The wire grid polarizing element according to any one of claims 1 to 5 , wherein the base portion has a thickness (TB) of 1 nm or more. 6. The cross-sectional shape of the ridges in the cross section perpendicular to the reflection axis direction of the wire grid polarizing element is trapezoidal, triangular, bell - shaped, or elliptical, the width of which narrows with increasing distance from the base. The wire grid polarizing element according to any one of . The wire grid polarization element according to any one of claims 1 to 7 , further comprising a protective film formed to cover at least the surface of said functional film. 9. The wire grid polarizer according to claim 8 , wherein said protective film includes a water-repellent coating or an oil-repellent coating. The wire grid polarization element according to any one of claims 1 to 9 , wherein said functional film further has a dielectric film. When θ is 30° or more and 60° or less,
The difference between the transmission axis transmittance (Tp(+)) of incident light with an incident angle of +θ and the transmission axis transmittance (Tp(−)) of incident light with an incident angle of −θ with respect to the wire grid polarizing element is within 3%, the wire grid polarizing element according to any one of claims 1 to 10 . The wire grid polarization element according to any one of claims 1 to 11 , wherein the functional film is a reflective film that reflects incident light. The wire grid polarization element according to any one of claims 1 to 12 , wherein the wire grid polarization element is a polarization beam splitter that splits oblique incident light into first polarized light and second polarized light. A method for manufacturing a hybrid wire grid polarizer made of an inorganic material and an organic material, comprising:
forming a grid structure material made of the organic material on the substrate made of the inorganic material;
a step of forming a grid structure in which a base portion provided on the substrate and a plurality of ridges projecting from the base portion are integrally formed by performing nanoimprinting on the grid structure material;
a step of forming a functional film that covers a portion of the ridge using a metal material;
including
In the step of forming the grid structure, forming the protruding portion having a tapered shape in which the width becomes narrower as the distance from the base portion increases,
In the step of forming the functional film,
The functional film covers the tip and the upper side of at least one side surface of the protruding portion, and covers the protruding portion without covering the lower side of both side surfaces of the protruding portion and the base portion. The surface of the functional film that wraps is rounded and bulges in the width direction of the ridge, and the maximum width (W _MAX ) of the functional film that covers and wraps the ridge extends from the bottom of the ridge. At a position 20% above the height of the protruded streak, the width (W B ) of the protruded streak is equal to or greater than the width (W _B ) of the protruded streak at the portion not covered with the functional film. When the coverage ratio (Rc) of the side surface is the ratio of the height (Hx) of the portion of the side surface of the ridge covered with the functional film to the height (H) of the ridge, A method of manufacturing a wire grid polarizing element, wherein the functional film is formed such that the coverage (Rc) is 30% or more and 70% or less . 15. The method of manufacturing a wire grid polarizing element according to claim 14 , wherein in the step of forming the functional film, films are alternately formed on the ridges from a plurality of directions by sputtering or vapor deposition. a light source;
a polarizing beam splitter arranged so that the incident light from the light source is incident at an incident angle within a predetermined range including 45° and splitting the incident light into a first polarized light and a second polarized light;
arranged so that the first polarized light reflected by the polarizing beam splitter or the second polarized light transmitted through the polarizing beam splitter is incident, and the incident first polarized light or the second polarized light A reflective liquid crystal display element that reflects and modulates the
a lens arranged so that the first polarized light or the second polarized light reflected and modulated by the reflective liquid crystal display element is incident through the polarizing beam splitter;
with
A projection display apparatus, wherein the polarizing beam splitter is composed of the wire grid polarizing element according to any one of claims 1 to 13 . 17. The projection display apparatus according to claim 16 , wherein said predetermined range of incident angles is 30[deg.] or more and 60[deg.] or less. 18. The projection display apparatus according to claim 16 , wherein a heat dissipation member is provided around said wire grid polarization element. A vehicle comprising the projection display device according to any one of claims 16-18 .

Images