JP4337524B2 - Optical compensation plate and projection type liquid crystal display device using the same - Google Patents

Description

  The present invention relates to an optical compensator suitable for a projection type liquid crystal display device, and further relates to a projection type liquid crystal display device using the same.

  The projection type liquid crystal display device is also called a liquid crystal projector, and is widely used as a device capable of enlarging a screen of a personal computer, a television or the like and projecting it on a screen.

  Projection-type liquid crystal display devices include a single-plate type that directly expands the spectral light from the color filter, a type that splits the three primary colors and then passes through a transmissive liquid crystal cell corresponding to each light, and a spectral that splits into the three primary colors. Then, there is a type in which the light is reflected by a reflective liquid crystal cell corresponding to each light. Here, an outline of the configuration of a projection type liquid crystal display device using transmission liquid crystal cells corresponding to the three primary colors, which currently occupies the mainstream, will be described with reference to FIG.

  Such a projection type liquid crystal display device usually has a light source system, a reflection / spectral system, and an enlarged projection system. The light source system includes a white light source 11 and a UV / IR cut filter 13, and the white light L from the white light source 11 is cut into ultraviolet rays and infrared rays by the UV / IR cut filter 13, and the first dichroic mirror. To be sent to 1. As the white light source 11, a metal halide lamp, a high-pressure mercury lamp, or the like is usually used.

  The reflection / spectral system includes four types of dichroic mirrors 1, 2, 3, 4 and two total reflection mirrors 5, 6, corresponding to red light R, green light G and blue light B, respectively, and liquid crystal cells 7R, 7G and 7B, light incident side polarization conversion elements 8R, 8G and 8B, light output side polarization conversion elements 9R, 9G and 9B, and condenser lenses 10R, 10G and 10B.

  The first dichroic mirror 1 transmits only the green light G and the blue light B, and the green light G and the blue light B transmitted therethrough are sent to the second dichroic mirror 2. The red light R reflected by the first dichroic mirror 1 is sent to the first total reflection mirror 5, where it is reflected, and then the red condenser lens 10R, incident side polarization conversion element 8R, liquid crystal. It is sent to the third dichroic mirror 3 through the cell 7R and the output side polarization conversion element 9R. The second dichroic mirror 2 transmits only the blue light B. Of the green light G and the blue light B transmitted through the first dichroic mirror 1, the blue light B transmitted through the second dichroic mirror 2 is used. Is sent to the second total reflection mirror 6 through the blue condenser lens 10B, the incident side polarization conversion element 8B, the liquid crystal cell 7B, and the emission side polarization conversion element 9B. The green light G reflected by the second dichroic mirror 2 passes through the green condensing lens 10G, the incident side polarization conversion element 8G, the liquid crystal cell 7G and the emission side polarization conversion element 9G, and passes through the third dichroic mirror 3. Sent to. The third dichroic mirror 3 transmits only the red light R. From the first total reflection mirror 5, the red condenser lens 10R, the incident side polarization conversion element 8R, the liquid crystal cell 7R, and the output side polarization conversion. The red light R that has passed through the element 9R passes through the third dichroic mirror 3 as it is, and from the second dichroic mirror 2, the green condenser lens 10G, the incident side polarization conversion element 8G, the liquid crystal cell 7G, and the emission side. The green light G that has passed through the polarization conversion element 9G is reflected by the third dichroic mirror 3 and sent to the fourth dichroic mirror 4 respectively. The fourth dichroic mirror 4 transmits only the red light R and the green light G, and the red light R and the green light G from the third dichroic mirror 3 are transmitted as they are, and the second total reflection. The blue light B from the mirror 6 is reflected here and sent to the projection lens 16.

  Here, the form in which the red light R is first split and then the green light G and the blue light B is split is shown here, but the order of splitting can be arbitrarily changed depending on the combination of the dichroic mirrors.

  The magnifying projection system has a projection lens 16, where an image corresponding to each light is magnified and a magnified image is projected onto the screen 17. The incident side polarization conversion elements 8R, 8G, and 8B and the emission side polarization conversion elements 9R, 9G, and 9B of the liquid crystal cells 7R, 7G, and 7B corresponding to the respective colors are used by being bonded to the liquid crystal cells 7R, 7G, and 7B. In some cases, the liquid crystal cells 7R, 7G, and 7B are usually spaced from each other, and this space serves as a cooling air passage. In addition, the incident-side polarization conversion elements 8R, 8G, and 8B are spaced from the condenser lenses 10R, 10G, and 10B. As described above, when the polarization conversion elements 8R, 8G, 8B, 9R, 9G, and 9B are arranged apart from the liquid crystal cells 7R, 7G, and 7B and the condenser lenses 10R, 10G, and 10B, the linear polarizing plate is made of glass or the like. Used in the form of being bonded to the reinforcing material.

  In such a projection type liquid crystal display device, each of the liquid crystal cells 7R, 7G, and 7B includes two polarization conversion elements, that is, incident side polarization conversion elements 8R, 8G, and 8B and output side polarization conversion elements 9R, 9G, and 9B. These polarization conversion elements 8 and 9 generate a large amount of heat because they transmit light having a light amount necessary for enlarging and projecting an image on a screen. In addition, when the red light R, the green light G, and / or the blue light B are polarized light, it is often necessary to rotate the polarization plane when entering the liquid crystal cells 7R, 7G, and 7B. Furthermore, the polarized light emitted from the liquid crystal cells 7R, 7G, and 7B may rotate the polarization plane again.

  In order to rotate the polarization plane, a phase difference plate may be used. Usually, the phase difference plate is used for the light source 11 side of the incident side polarization conversion elements 8R, 8G, and 8B or the output side polarization conversion elements 9R, 9G, and 9B. Arranged on the projection lens 16 side. As the retardation plate, a resin plate is usually used from the viewpoint of availability and price. This phase difference plate is used in the form of being bonded to a linear polarizing plate in the incident side polarization conversion elements 8R, 8G, 8B or the emission side polarization conversion elements 9R, 9G, 9B.

  Such a projection type liquid crystal display device has a problem that the contrast of an image projected on a screen is not high due to the influence of the birefringence of the liquid crystal cell.

  In view of this, Japanese Patent Application Laid-Open No. 2000-137202 (Patent Document 1) proposes that an optical compensation layer relaxes the contrast of the in-image distribution and the brightness deviation in the image component in the projection type liquid crystal display device. ing. Japanese Patent Laid-Open No. 2000-352615 (Patent Document 2) discloses that a polarizing plate is attached to glass having a small average linear expansion coefficient and is used as an incident-side or output-side polarization conversion element of a projection type liquid crystal display device. And an optical anisotropic body other than the liquid crystal cell may be disposed at a position between the incident side polarization conversion element and the output side polarization conversion element and away from any polarizing plate. Proposed. Examples of these optical compensation layers and optical anisotropic bodies include those obtained by hybrid alignment of discotic liquid crystals, for example, those disclosed in JP-A-8-50206 (Patent Document 3). In the configurations specifically disclosed in these Patent Documents 1 and 2, one optical compensation layer or one optical anisotropic body is disposed on each of the front and back sides of the liquid crystal cell, and a polarizing plate is disposed on each outer side. One by one. On the other hand, Japanese Patent Laid-Open No. 2002-14345 (Patent Document 4) provides an optical compensation layer on the light exit side of a liquid crystal cell to perform optical compensation for liquid crystal molecules present in the light incident side region of the liquid crystal layer. And two or three optical compensation layers are also proposed. However, the projection type liquid crystal display device using the optical compensation layer or the optical anisotropic body disclosed in Patent Literature 1, Patent Literature 2 and Patent Literature 4 has a problem that color unevenness in black display is conspicuous. It was.

JP 2000-137202 A JP 2000-352615 A JP-A-8-50206 JP 2002-14345 A

  The present inventor intends to develop an optical compensator that can increase the contrast of a projection-type liquid crystal display device, hardly cause color unevenness in black display even when used for a long period of time, and thus can realize high display quality over a long period of time. Have been doing research. As a result, a transparent film having a small photoelastic coefficient and having an antireflection layer on the surface in contact with air, an optical compensation film formed by applying a liquid crystalline compound to a base film, and a transparent glass plate are laminated. Thus, the present inventors have found that high-quality image display can be maintained over a long period of time without causing color unevenness in black display of an image projected on a screen.

That is, the optical compensator of the present invention has a photoelastic coefficient of 7 × 10 ⁻¹³ cm ² / dyne or less, a transparent film having an antireflection layer formed on the surface, and a liquid crystal compound applied to the base film The optical compensation film thus formed and a transparent glass plate are laminated so that the antireflection layer of the transparent film is on the outermost side.

  This optical compensator is used by being incorporated in a projection type liquid crystal display device. Therefore, the present invention also provides a projection type liquid crystal display device in which the above-mentioned optical compensation plate is disposed on at least one surface side of a liquid crystal cell. More specifically, the projection type liquid crystal display device includes a white light source and an optical system having a dichroic coat layer for splitting white light from the white light source into light of three primary colors of red light, green light, and blue light. A liquid crystal cell, a polarization conversion element, and the optical compensation plate. The optical system in this case has, for example, a dichroic mirror, a total reflection mirror, and a condenser lens for splitting white light from a white light source into light of three primary colors of red light, green light, and blue light.

  The optical compensator of the present invention is obtained by arranging a specific transparent film having an antireflection layer and an optical compensation film in a specific order, and is effectively used for a projection type liquid crystal display device. The projection type liquid crystal display device in which the optical compensator is arranged has a high contrast of the projected image, no screen unevenness of black display, and excellent display quality.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail. In the present invention, a transparent film having an antireflection layer on the surface and a small photoelastic coefficient is used. This transparent film is made of a resin having a photoelastic coefficient of 7 × 10 ⁻¹³ cm ² / dyne or less. The photoelastic coefficient of the transparent resin film is preferably 6 × 10 ⁻¹³ cm ² / dyne or less. By using such a transparent film made of a resin having a small photoelastic coefficient, it is possible to prevent the occurrence of retardation due to thermal deformation and distortion of the film. When the photoelastic coefficient of the resin film is larger than 7 × 10 ⁻¹³ cm ² / dyne, a new phase difference is generated due to the distortion caused by heat, and the polarization is disturbed, resulting in color unevenness in the image. Cheap. There is no particular limitation on the lower limit of the photoelastic coefficient. For example, a resin having a photoelastic coefficient of about 0.1 × 10 ⁻¹³ cm ² / dyne may be used.

Photoelasticity refers to a phenomenon in which, when an external force is applied to a material having isotropic properties, ie, birefringence of 0, and an internal stress is exerted, it exhibits optical anisotropy and exhibits birefringence. When the stress acting on the substance (force acting per unit area) is σ and the birefringence is Δn, the stress σ and the birefringence Δn are theoretically proportional, and the following equation (1)
Δn = Cσ (1)
This C is a photoelastic coefficient. In other words, if the stress σ acting on the substance is taken on the horizontal axis and the birefringence Δn when the stress is applied on the vertical axis, the relationship between them is theoretically a straight line, and the gradient of this straight line is the photoelasticity. It is a coefficient.

  The glass transition temperature of the resin constituting the transparent film is preferably 130 ° C. or higher, more preferably 140 ° C. or higher. When the glass transition temperature of the transparent resin film is lower than 130 ° C., thermal deformation becomes significant. There is no special restriction | limiting in the upper limit of the glass transition temperature of a transparent resin film, For example, resin whose glass transition temperature is about 300 degreeC may be sufficient.

Specific examples of such a resin having a small photoelastic coefficient include a cyclic polyolefin resin film having a cyclic olefin such as norbornene as a monomer, a resin film made of a copolymer of cyclic olefin such as norbornene and styrene, and the like. Is mentioned. Examples of the cyclic polyolefin-based resin film include “ARTON” (glass transition temperature: about 170 ° C., photoelastic coefficient: about 4 × 10 ⁻¹³ cm ² / dyne) sold by JSR Corporation, Sekisui Chemical Co., Ltd. ( "Essina" (glass transition temperature of about 140 ° C, photoelastic coefficient of about 6 × 10 ^-13 cm ² / dyne) sold by Co., Ltd., "ZEONOR" (glass transition temperature of about 6 x 10 ^-13 cm ² / dyne) 136 ° C., photoelastic coefficient of about 6 × 10 ⁻¹³ cm ² / dyne). The thickness of the transparent film is usually about 20 μm to 1 mm, preferably about 40 to 150 μm.

The transparent film has a smaller in-plane retardation value, and is preferably, for example, 20 nm or less, more preferably 10 nm or less, and particularly preferably 5 nm or less. If the in-plane retardation value exceeds 20 nm, the display quality of the image may be lowered. Further, the retardation value in the thickness direction is preferably as small as possible, for example, 50 nm or less, more preferably 30 nm or less, and particularly preferably 10 nm or less. If the retardation value in the thickness direction exceeds 50 nm, the display quality of the image may be lowered. Here, the retardation value R and the thickness direction retardation value Rt in the plane, the refractive indices n _x maximum direction refractive index in the plane, the direction of the refractive index perpendicular thereto in the plane n _y, thickness When the refractive index in the direction is n _z and the thickness of the film is d, the values are defined by the following equations (2) and (3), respectively.
_{R = (n x -n y)} × d (2)
Rt = _{[(n x + n y) /} 2-n z ] × d (3)

  This transparent film also preferably contains an ultraviolet absorber.

  In the present invention, a transparent film having an antireflection layer formed on the outer surface of the transparent film having a small photoelastic coefficient as described above, that is, the surface in contact with air is used. The antireflection layer is a layer that reduces reflected light at the interface with air, and prevents stray light from being generated due to the reflected light. It is preferable to provide an antireflection layer having a reflectance of 2% or less, particularly 1% or less, at this surface at a wavelength of 550 nm. Examples of the antireflection layer include those commonly used, for example, a single layer or a multilayer formed of a compound selected from metals, metal oxides, and metal fluorides. Examples of the metal include silver, and examples of the metal oxide include silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, yttrium oxide, and zirconium oxide. Examples of the metal fluoride include And magnesium fluoride. This antireflection layer may be a single layer, or may be composed of multiple layers, for example, two layers, three layers, or four or more layers. The thickness of the antireflection layer and the thickness of each layer when it is a multilayer are appropriately selected depending on the number of layers, the refractive index of the substance used for each layer, and the like. In order to improve the adhesion between the antireflection layer and the transparent film, an acrylic coat layer or a hard coat layer may be provided between them.

  The contact angle on the surface having the antireflection layer is preferably 80 ° or more, more preferably 100 ° or more. The contact angle here is a value when water is used as the liquid. If the contact angle on the surface in contact with air is less than 80 °, fine particles are likely to adhere to the projection liquid crystal display device using the optical compensator having such a surface, and the contrast when used over a long period of time. It tends to decrease. The upper limit of the contact angle is 180 °.

  When the surface of the antireflection layer satisfies the contact angle specified here, a transparent film having such an antireflection layer can be used as it is in the present invention. However, in many cases, the normal antireflection layer does not have the contact angle specified here. In this case, the contact angle is set by providing a layer made of a fluorine compound on the upper surface of the antireflection layer. Can be achieved. The layer made of a fluorine compound can be provided by coating the surface with a coating solution containing the compound. The fluorine compound used for this purpose is not particularly limited as long as the contact angle of the surface can be 80 ° or more, and those usually used for preventing surface contamination, for example, fluorine-containing silane compounds are used. Can do. Such a fluorine compound has been conventionally used in the field of coating and the like in order to prevent dirt such as fingerprints from adhering to the surface.

  In the present invention, a transparent film having such an antireflection layer is used in combination with a specific optical compensation film. This optical compensation film is obtained by applying and aligning a liquid crystal compound on the surface of a base film, and an optical phase difference caused by liquid crystal molecules in a liquid crystal cell when incorporated in a projection type liquid crystal display device. To compensate.

  Examples of the base film of the optical compensation film include polycarbonate resins such as modified polycarbonate having a fluorene skeleton and general polycarbonate obtained from bisphenol A, cellulose resins such as diacetyl cellulose and triacetyl cellulose, and norbornene monomers. And cyclic polyolefin resins, polysulfone resins, polyether sulfone resins, polyester resins, polyimide resins, polyamide resins, polyarylate resins, and the like. The thickness of this base film is usually about 10 to 1,000 μm. The liquid crystal compound applied thereon may be, for example, a discotic liquid crystal compound or a polymer liquid crystal compound having a triphenylene skeleton. The method for aligning the liquid crystalline compound may be a normal method. For example, the substrate film surface is previously subjected to an alignment treatment, the liquid crystalline compound is applied thereto, dried, and then the alignment of the liquid crystalline compound is performed by heat treatment. A fixing method can be used. Such an optical compensation film in which a liquid crystalline compound is applied and oriented is described in Patent Document 3, for example. As a commercially available optical compensation film in which a liquid crystal compound is coated and oriented, for example, it may be expressed as a “wide view film” (“WV film”) sold by Fuji Photo Film Co., Ltd. WV A 03B ”,“ WV A 12B ”,“ WV A 038 ”,“ WV A 128 ”, etc.) and“ Nisseki LC Film ”,“ Nissan LC Film ”sold by Nippon Oil Corporation Stone NH film ”and“ Nisseki NR film ”.

In the present invention, the transparent film having the antireflection layer described above and the optical compensation film are bonded to a transparent glass plate to obtain an optical compensation plate. As the transparent glass plate, a normal silica glass plate or quartz glass plate called blue plate glass or white plate glass can be used. It is also preferable to use sapphire glass or quartz glass having high thermal conductivity. The sapphire glass is a single crystal of alumina (Al ₂ O ₃ ), and for example, a sapphire glass formed in a plate shape by an EFG method (Edge-defined Film-fed Growth method) is used. The quartz glass is a single crystal of SiO ₂ and may be a synthetic quartz or a natural quartz. It is preferable to have an antireflection layer on one surface of the transparent glass plate, that is, the exposed surface. The thickness of the transparent glass plate is usually about 0.1 to 2 mm, preferably 0.3 mm or more, and more preferably 0.8 mm or less. The area of the transparent glass plate is appropriately selected depending on the size of the target projection type liquid crystal display device. Examples of typical dimensions include a rectangle or a square having a side of 10 to 100 mm, a circle or an ellipse having a diameter of 5 to 100 mm, and the like.

  A transparent film and an optical compensation film are laminated on the transparent glass plate. At this time, the transparent film becomes one outer surface and is usually laminated in the order of transparent glass plate / optical compensation film / transparent film. The area of the transparent film and the optical compensation film is usually approximately the same as or slightly smaller than the area of the transparent glass plate. If the area is slightly smaller, it may be easier to adhere to the glass surface, and it is preferable to reduce the area of the transparent film and the optical compensation film so that it can be applied about 0.5 to 5 mm from the edge of the transparent glass plate. .

  The transparent film and the optical compensation film, and the glass plate and the optical compensation film are usually laminated via an adhesive layer. As the adhesive constituting the adhesive layer, for example, a pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive or a urethane pressure-sensitive adhesive is used. Pressure sensitive adhesives generally provide a transparent and optically isotropic adhesive layer. The pressure-sensitive adhesive is also called an adhesive. The thickness of the adhesive layer is usually about 10 to 60 μm.

  In the optical compensation plate of the present invention, it is more preferable to laminate two optical compensation films each having a liquid crystal compound coated on a base film so as to be adjacent to each other. That is, the transparent film having the antireflection layer / the first optical compensation film / the first optical film so that the two optical compensation films are located on one side of the glass plate and the antireflection layer of the transparent film is the outermost side. When the two optical compensation films are arranged in this order, the effect of improving the contrast is further enhanced. In this case, it is preferable to arrange the two optical compensation films so that their orientation axes are substantially orthogonal to each other. Here, “substantially orthogonal” means that orthogonal (90 °) is preferable, but it means that it may be shifted within about ± 5 °. The term “substantially” used when expressing the angular arrangement in other parts of this specification has the same meaning. Further, of the two optical compensation films, the first optical compensation film close to the transparent film is a linearly polarizing plate in a polarization conversion element in which the orientation axis is arranged adjacently when incorporated in a projection type liquid crystal display device. It is preferable to arrange so as to be substantially orthogonal to or substantially parallel to the absorption axis. Further, these two optical compensation films are preferably arranged so that the surface opposite to the surface coated with the liquid crystalline compound, that is, the base film side overlaps.

  1 and FIG. 2 are cross-sectional schematic views showing examples of the optical compensation plate according to the present invention. In the example shown in FIG. 1, a transparent film 21 and an optical compensation film 30 are laminated and bonded to a glass plate 23 on the optical compensation film 30 side to form an optical compensation plate 20. Here, the optical compensation film 30 is obtained by applying and aligning a liquid crystalline compound layer 32 on a base film 31, a transparent film 21 on the liquid crystalline compound layer 32 side, and a glass plate on the base film 31 side. 23 is bonded. An antireflection layer 27 is provided on the side of the transparent film 21 in contact with air. An antireflection layer 28 is also provided on the outer surface of the glass plate 23 opposite to the surface to which the optical compensation film 30 is bonded. When the glass plate 23 has optical anisotropy, it is necessary to make the crystal axis and the polarization axis of the transmitted polarized light parallel or orthogonal to each other. For example, when the glass plate 23 is sapphire glass, The C axis and the polarization axis of the transmitted polarized light are arranged so as to be substantially parallel or substantially orthogonal.

  In the example shown in FIG. 2, in addition to the layer configuration of FIG. 1, a second optical compensation film 40 is disposed between the optical compensation film 30 and the glass plate 23 to form the optical compensation plate 20. Therefore, the optical compensation film 30 disposed on the transparent film 21 side is taken as a first optical compensation film. The second optical compensation film 40 is also a substrate film 41 having a liquid crystal compound layer 42 applied and oriented. In the example shown in FIG. 2, the two optical compensation films 30 and 40 are arranged so that their orientation axes are substantially orthogonal. These two optical compensation films are arranged so that the surface opposite to the surface on which the liquid crystal compound layers 32 and 42 are applied, that is, the base film 31 and 41 side overlap.

  3 to 5 show the relationship between the axial angles of the two optical compensation films 30 and 40 when two optical compensation films 30 and 40 are laminated as shown in FIG. Both show the relationship of the axial angle when two optical compensation films, that is, the first optical compensation film 30 and the second optical compensation film 40 are laminated in this order on one side of the transparent film 21. Is. In any of the figures, the alignment axis of the first optical compensation film 30 and the alignment axis of the second optical compensation film 40 are arranged so as to be substantially orthogonal. That is, the right direction of the long side of each of the optical compensation films 30 and 40 is 0 °, and in FIG. 3, the orientation axis of the first optical compensation film 30 is the 135 ° direction, and the orientation axis of the second optical compensation film 40 is 4 and 5, the orientation axis of the first optical compensation film 30 is set to the 270 ° direction, and the orientation axis of the second optical compensation film 40 is set to the 180 ° direction or the 0 ° direction. In FIGS. 4 and 5, the direction of the arrow indicating the orientation axis of the second optical compensation film 40 is reversed. The direction of the arrow means the direction of rubbing for orientation.

  The optical compensator of the present invention can be suitably used for a projection type liquid crystal display device. For example, in a projection-type liquid crystal display device, it is used by inserting into a light path of white light from a white light source or into a light path of each primary color light that is red light, green light, or blue light after white light is dispersed. it can.

  Specifically, in the projection type liquid crystal display device as shown in FIG. 6, between the liquid crystal cells 7R, 7G, 7B corresponding to the three primary colors and the incident side polarization conversion elements 8R, 8G, 8B, or the outgoing side polarized light. It can be used by being disposed between the conversion elements 9R, 9G, 9B and the liquid crystal cells 7R, 7G, 7B. All between the incident side polarization conversion elements 8R, 8G, 8B and the liquid crystal cells 7R, 7G, 7B, or all between the output side polarization conversion elements 9R, 9G, 9B and the liquid crystal cells 7R, 7G, 7B. It is more effective to arrange the optical compensator of the present invention. This optical compensator is usually such that the glass plate 23 shown in FIGS. 1 and 2 is on the side of the polarization conversion elements 8R, 8G, 8B or 9R, 9G, 9B, in other words, the transparent film 21 is made of glass. It arrange | positions so that it may become a side nearer to the liquid crystal cells 7R, 7G, and 7B than the plate 23.

  An example of the arrangement in such a projection type liquid crystal display device is shown in a schematic sectional view in FIG. FIG. 7A shows an example in which the optical compensation plate 20 shown in FIG. 1 is disposed between the liquid crystal cell 7 and the polarization conversion element 8 or 9 on the incident side or the emission side, and FIG. 2 is an example in which the optical compensation plate 20 shown in FIG. 2 is disposed between the liquid crystal cell 7 and the polarization conversion element 8 or 9 on the incident side or the emission side. In either case, the transparent film 21 constituting the optical compensation plate 20 is disposed on the liquid crystal cell 7 side, and the glass plate 23 is disposed on the polarization conversion element 8 or 9 side. Although not shown, the polarization conversion element 8 or 9 may be attached to the glass surface opposite to the surface on which the optical compensation film 30 or 40 of the optical compensation plate is attached. Furthermore, a polarizing plate may be directly pasted on the glass surface opposite to the surface on which the optical compensation film 30 or 40 of the optical compensation plate is pasted. In this case, the number of parts is reduced. Not only has cost merit, it also makes it easier to blow air and improves cooling efficiency. Furthermore, particularly for the polarization conversion element on the exit side, a polarizing plate with high transmittance (pre-polarizing plate) is used as the optical compensation film 30 or 40 for the optical compensation plate for the purpose of protecting the polarizing plate disposed therein. Affixed to the glass surface opposite to the affixed surface, a normal polarizing plate (main polarizing plate) on the outside of the glass surface, and the transmission axis is parallel to the transmission axis of the previous pre-polarizing plate Thus, it can be a polarization conversion element. In this case, light is absorbed to some extent by the polarizing plate (pre-polarizing plate) having a high transmittance, so that the light absorption by the main polarizing plate disposed thereafter can be reduced. The polarizing plates with high transmittance used for such purposes include “STX8C2A-HC-AR”, “STX8B2A-HC-AR”, “STX8A2A-HC-AR” sold by Sumitomo Chemical Co., Ltd. -OB "etc.

  On the other hand, there is also a projection type liquid crystal display device of the type that directly expands the spectral light from the color filter in a single plate format, but in this case, in the optical path of white light, before or after the liquid crystal cell including the color filter, The optical compensator of the present invention is arranged.

  Next, the present invention will be described in more detail by showing specific examples, but the present invention is not limited to these examples.

Example 1
Cyclic polyolefin-based transparent resin film, “Arton” (photoelastic coefficient of about 4 × 10 ⁻¹³ cm ² / dyne) sold by JSR Co., Ltd. with antireflection treatment and fluorine-containing silane compound Were processed in this order to obtain a transparent film. This film had an in-plane retardation value of 4 nm and a retardation value in the thickness direction of 46 nm. An optical compensation film in which a liquid crystal compound is coated and oriented on a base film on the surface opposite to the antireflection treatment surface of this transparent film, which is a “wide view film” sold by Fuji Photo Film Co., Ltd. Two sheets of WV A 03B "were laminated via adhesives. At this time, the two optical compensation films are arranged at the same axial angle as shown in FIG. 5 and bonded so that the surface of the base film opposite to the surface on which each liquid crystal compound layer is formed faces each other. did. Furthermore, an antireflection treatment is applied to one side of a sapphire glass plate having a diagonal size of 0.9 inch (about 23 mm) sold by Kyocera Corporation, and the transparent film / The laminated body of the optical compensation film / second optical compensation film was bonded to the liquid crystal compound layer side of the second optical compensation film to produce an optical compensation plate having the configuration shown in FIG. Under the present circumstances, it bonded so that the orientation axis | shaft of a 2nd optical compensation film and the C axis | shaft of sapphire glass might correspond.

  Between the red (R), green (G), and blue (B) liquid crystal panels of the projection type liquid crystal display device and the output side polarization conversion elements, the optical compensation plate obtained above is a glass plate. When set and observed so as to be on the side of the output side polarization conversion element, the contrast on the screen was increased, the unevenness of the black display was small, and the display quality was improved.

Comparative Example 1
One side of a triacetylcellulose film (photoelastic coefficient of about 10 × 10 ⁻¹³ cm ² / dyne, in-plane retardation value 7 nm, retardation value in the thickness direction 56 nm) sold by Fuji Photo Film Co., Ltd. as a transparent film An optical compensator was produced in the same manner as in Example 1 except that a material subjected to antireflection treatment was used. When this optical compensator was set in a projection type liquid crystal display device in the same manner as in Example 1 and observed, the contrast on the screen increased, but black unevenness occurred and the display quality was low.

It is a cross-sectional schematic diagram which shows an example of the optical compensator which concerns on this invention. It is a cross-sectional schematic diagram which shows another example of the optical compensator which concerns on this invention. In the optical compensator concerning the present invention, it is an arrangement figure showing an example of the relation of an axis angle in the case of laminating a transparent film and two optical compensation films. In the optical compensator according to the present invention, it is an arrangement diagram showing another example of the relationship of the axial angle when a transparent film and two optical compensation films are laminated. In the optical compensator according to the present invention, it is a layout diagram showing still another example of the relationship of the axial angles when a transparent film and two optical compensation films are disposed. It is explanatory drawing which shows schematically the structural example of a projection type liquid crystal display device. It is a cross-sectional schematic diagram which shows the example of arrangement | positioning in the case of setting it as a projection type liquid crystal display device combining the optical compensator of this invention with a liquid crystal cell.

Explanation of symbols

1,2,3,4 ... Dichroic mirror,
5, 6 ... Total reflection mirror,
7, 7R, 7G, 7B ... liquid crystal cell,
8, 8R, 8G, 8B ... incident side polarization conversion element,
9, 9R, 9G, 9B... Output side polarization conversion element,
10R, 10G, 10B ... Condensing lens,
L: White light (light source light),
R …… Red light,
G ... Green light,
B …… Blue light,
11 …… White light source,
13 …… UV / IR cut filter,
16. Projection lens,
17 …… Screen,
20 …… Optical compensation plate,
21 …… Transparent film,
23 …… Glass plate,
27..Antireflection layer provided on transparent film,
28 …… Antireflection layer on the glass plate side,
30, 40 ... Optical compensation film,
31, 41 ... Base film of optical compensation film,
32, 42 ... Liquid crystalline compound layer of the optical compensation film.

Claims (7)

A transparent film having a photoelastic coefficient of 7 × 10 ⁻¹³ cm ² / dyne or less and having an antireflection layer formed on the surface, an optical compensation film obtained by applying a liquid crystalline compound to a base film, and transparent An optical compensator, wherein a transparent glass plate is laminated so that the antireflection layer of the transparent film is on the outermost side.   The optical compensation plate according to claim 1, wherein two optical compensation films obtained by applying a liquid crystalline compound to the base film are laminated.   The optical compensation plate according to claim 2, wherein the two optical compensation films are arranged so that their orientation axes are substantially orthogonal to each other.   The optical compensation plate according to claim 2 or 3, wherein the two optical compensation films are laminated so that the surface of the base film opposite to the surface on which the liquid crystal compound is applied overlaps.   The optical compensation plate according to any one of claims 1 to 4, wherein the transparent film has an in-plane retardation value of 20 nm or less and a retardation value in the thickness direction of 50 nm or less.   The optical compensation plate according to any one of claims 1 to 5, wherein the transparent glass plate is sapphire glass. 7. A projection type liquid crystal display device, wherein the optical compensation plate according to claim 1 is disposed on one surface side of a liquid crystal cell.

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