JP6766367B2 - Display device and liquid crystal display device - Google Patents

Description

The present invention relates to a display device and a liquid crystal display device.

A liquid crystal display device such as a liquid crystal television illuminates a liquid crystal panel having video information from the back side with a surface light source device. As a result, the illumination light passes through the liquid crystal panel to obtain image information and is emitted to the observer side so that the observer can visually recognize the image. On the other hand, due to the nature of the liquid crystal panel, there is a limit to the light that can be effectively used, and it is necessary to devise a way to efficiently use the light from the light source.

Patent Document 1 discloses a video source unit in which a surface light source, a prism sheet, an optical functional layer (a layer in which light transmitting portions and light absorbing portions are alternately arranged), and a liquid crystal panel are laminated in this order. There is. As a result, the direction of the light incident on the liquid crystal panel is brought closer to the panel surface normal direction of the liquid crystal panel, and the light utilization efficiency is improved.
Similarly, in Patent Document 2, a light source, a brightness increasing film (a sheet in which a plurality of prisms having a top facing the observer side), a reflective polarizing film, and an LCF (a light transmitting portion and a light absorbing portion are alternately arranged). Arranged films) and liquid crystal panels are arranged in this order. As a result, the direction of the light emitted from the light source can be brought closer to the panel surface normal direction of the liquid crystal panel, and the light utilization efficiency can be improved. Further, the light incident on the LCF at a large angle with respect to the panel surface of the liquid crystal panel is absorbed by the light absorption unit provided here.

For example, a car navigation device or the like installed in an automobile is provided with a liquid crystal display device as described in Patent Documents 1 and 2 to prevent reflection on a windshield or the like. Further, since the liquid crystal display device also has a function of absorbing external light, the car navigation device and the like can be designed neatly without a hood.

JP-A-2010-217871 Japanese Patent Publication No. 2011-501219

On the other hand, instruments such as speedometers provided in automobiles and the like are provided with a hood, and the hood blocks outside light. Therefore, it was necessary to provide a hood for instruments such as speedometers, and the design was limited.
When the optical sheet described in Patent Documents 1 and 2 is applied to the panel of the dashboard, the main image is displayed in addition to the image displayed at the original display position (hereinafter, may be referred to as "main image"). There arises a phenomenon in which an image is projected at a display position different from that of the above, that is, a problem that an image called "double image" or "ghost" is generated.

Therefore, in view of the above problems, it is an object of the present invention to provide a display device capable of absorbing external light and suppressing ghosts from being visually recognized from the front.

Hereinafter, the present invention will be described. Reference numerals in the accompanying drawings are added in parentheses to facilitate understanding of the present invention, but the present invention is not limited to the illustrated form.

As a result of diligent studies by the inventor, it has been found that ghosts tend to be visually recognized when the light source and the optical sheet are arranged at a predetermined interval. That is, the meter or the like equipped on the dashboard is equipped with a meter needle or an indicator, and the optical sheet cannot be directly arranged on the meter or the like. Therefore, the meter or the like and the optical sheet have a predetermined distance. Is placed. It was found that ghosts tend to be visible when arranged in this way. This will be described in detail later with reference to FIG.
Further, as a result of further diligent studies, the inventor has found that it is possible to suppress the ghost from being visually recognized from the front by appropriately adjusting the cross-sectional shape of the optical sheet and the distance between the light source and the optical sheet. did.
The present invention has been completed based on the above findings.

The invention according to claim 1 is a display device including a display light emitting unit (120) which is an instrument of an automobile and an optical sheet (10) arranged on the observer side from the display light emitting unit. Includes a substrate layer (11) and an optical functional layer (12), the optical functional layer having a predetermined cross section and extending in one direction along the surface of the substrate layer, which is different from the extending direction. A plurality of light transmitting portions (13) arranged at predetermined intervals in the direction and a light absorbing portion (14) formed at intervals of adjacent light transmitting portions are provided, and the width of the light transmitting portion is the display light emitting unit. The side is wide and the observer side is narrow, the optical functional layer has a distance of 5 mm or more and 50 mm or less from the display light emitting part, the optical sheet is arranged so as not to touch the display light emitting part, and the light transmitting part and the light absorbing part are arranged. The interface with is polygonal or curved, and the light is reflected at the interface between the light transmitting part and the light absorbing part, and the light reflected again at the interface with the other layer adjacent to the optical functional layer is displayed. back to the light emitting portion side, the light transmitting portions and the light absorbing portion is configured, a display device.

Here, the "display light emitting unit" is a light emitting unit in which the display content is formed. For example, instrument panels, meter hands, indicators, etc. provided on the dashboard of an automobile. These allow the observer to visually recognize the displayed contents by emitting light or using a light source.

The invention according to claim 2 is the display device according to claim 1, wherein Nt-Nr exceeds 0 when the refractive index of the light transmitting portion is Nt and the refractive index of the light absorbing portion is Nr.

The invention according to claim 3 is the display device according to claim 1, wherein Nt-Nr becomes 0 when the refractive index of the light transmitting portion is Nt and the refractive index of the light absorbing portion is Nr.

The invention of claim 4 is a display device according to claim 1 other layer is a protective layer.

The invention according to claim 5 is the display device according to any one of claims 1 to 4 , further comprising a panel arranged on the observer side of the optical sheet, wherein the panel is a plate-shaped member that transmits light. is there.

The invention according to claim 6 is a liquid crystal display device including the display device according to any one of claims 1 to 5 , wherein the display device includes a liquid crystal panel in a display light emitting unit.

According to the present invention, a display device that absorbs external light and can suppress ghosts from being visually recognized from the front even if the display light emitting unit is arranged at a distance of 5 mm or more from the optical functional layer. Can be provided.

It is a figure explaining the display device 100 which concerns on one embodiment of this invention. It is an exploded perspective view explaining the panel unit 110 and the display light emitting part 120. FIG. 2 is a cross-sectional view taken along the line shown by III-III in FIG. FIG. 3 is an enlarged view focusing on the optical sheet 10. It is a figure explaining the form in which the short upper base of the light transmission part 13 of the optical sheet 10 is arranged in the direction that the display light emitting part side, and the long lower bottom is an observer side. It is a figure explaining the optical sheet 40 which concerns on other embodiment of this invention.

Hereinafter, the present invention will be described based on the form shown in the drawings. However, the present invention is not limited to these forms.

FIG. 1 is a diagram illustrating a display device 100 according to one embodiment of the present invention. In FIG. 1, an automobile instrument is illustrated as the display device 100. The display device 100 includes a panel unit 110 and a display light emitting unit 120, and is housed in a housing 130.

The panel unit 110 is arranged on the observer side of the display light emitting unit.

FIG. 2 is an exploded perspective view illustrating the panel unit 110 and the display light emitting unit 120. Further, FIG. 3 shows a part of an exploded cross-sectional view of the panel unit 110 and the display light emitting unit 120 when cut along the line shown by III-III in FIG.

The panel unit 110 includes an optical sheet 10 and a panel 20. In FIG. 2, the upper part of the paper surface is the observer side, and the lower part of the paper surface is the display light emitting portion side.

As can be seen from FIG. 2, the optical sheet 10 includes a base material layer 11 formed in a sheet shape and an optical functional layer 12 provided on the surface of the base material layer 11 on the observer side.

As will be described later, the optical sheet 10 changes the traveling direction of the light incident from the incoming light side and emits it from the light emitting side, and controls the ghost so that it is not recognized by the driver or a viewer from the front. This function makes it possible for the observer to see only the main image. Further, the optical sheet 10 is provided with a function (light absorption function) of absorbing light traveling at a large angle from the front on the observer side.

As shown in FIGS. 2 and 3, the base material layer 11 is a flat plate-shaped sheet-like member that supports the optical functional layer 12.
Various materials can be used as the material forming the base material layer 11. However, a material that is widely used as a material for an optical sheet incorporated in a display device, has excellent mechanical properties, optical properties, stability, workability, and the like, and can be obtained at low cost can be used. Examples thereof include polyethylene terephthalate (PET), triacetyl cellulose (TAC), methacrylic resin, polycarbonate and the like. Among these, it is preferable to use TAC, methacrylic resin, or polycarbonate having less birefringence. Furthermore, polycarbonate having a high glass transition point is desirable for applications that require high heat resistance, such as in-vehicle applications. Specifically, the glass transition point of polycarbonate is 143 ° C, and it is generally suitable for in-vehicle applications where durability at 105 ° C is required.

The optical functional layer 12 is a layer laminated on the surface of the base material layer 11 on the observer side, and light transmitting portions 13 and light absorbing portions 14 are alternately arranged along the layer surface. The x shown in FIG. 3 represents the distance between the optical functional layer 12 and the display light emitting unit 120, and is arranged at a distance of 5 mm or more. It is preferably 50 mm or less.

A protective layer that protects the optical functional layer 12 may be further laminated on the surface of the optical functional layer 12 on the observer side. By laminating the protective layer, it is possible to impart the effect of protecting the optical functional layer 12 from external damage and the like, and the effect of suppressing warpage when the optical sheet 10 is produced. As the material used for the protective layer, the same material as the above-mentioned base material layer can be used. Further, the protective layer may be subjected to antireflection treatment, antiglare treatment, antistatic treatment, hard coat treatment and the like.

FIG. 4 is an enlarged view of a part of FIG. 3 focusing on the base material layer 11 and the optical functional layer 12. The optical functional layer 12 has a cross section shown in FIG. 4 and has a shape extending to the back / front side of the paper surface. That is, in the cross section shown in FIG. 4, a light transmitting portion 13 having a substantially trapezoidal shape and a light absorbing portion 14 having a substantially trapezoidal cross section formed between two adjacent light transmitting portions 13 are provided.

The light transmitting portion 13 is a portion whose main function is to transmit light. In this embodiment, in the cross sections shown in FIGS. 3 and 4, a long lower bottom on the base material layer 11 side and the opposite side (observer side). ) Is an element having a substantially trapezoidal cross-sectional shape with a short upper bottom. The light transmitting portions 13 maintain the cross section along the layer surface of the base material layer 11 and extend in the above-mentioned directions, and are arranged at predetermined intervals in a direction different from the extending direction. An interval having a substantially trapezoidal cross section is formed between the adjacent light transmitting portions 13. Therefore, the interval has a trapezoidal cross section having a long lower base on the upper bottom side (observer side) of the light transmitting portion 13 and a short upper base on the lower bottom side (display light emitting portion side) of the light transmitting portion 13. The light absorbing portion 14 is formed by filling the space with the necessary materials described later. In this embodiment, the adjacent light transmitting portions 13 are connected by a long lower bottom side.

The light transmitting portion 13 has a refractive index of Nt. Such a light transmitting portion 13 can be formed by curing the light transmitting portion constituent composition. Details will be described later. The value of the refractive index Nt is not particularly limited, but as will be described later, the refractive index is determined from the viewpoint of appropriately reflecting light (including total reflection) at the interface with the light absorbing portion 14 on the slope of the trapezoidal cross section. It is preferably 1.55 or more. However, since a material having an excessively high refractive index is often fragile, the refractive index is preferably 1.61 or less. More preferably, it is 1.56 or less.

The light absorbing portion 14 functions as an interstitial portion formed between the adjacent light transmitting portions 13 at the above-mentioned intervals, and has a cross-sectional shape similar to the cross-sectional shape of the intervals. Therefore, the long lower base faces the observer side, and the short upper base faces the display light emitting portion side. The light absorbing unit 14 has a refractive index of Nr and is configured to be able to absorb light. Specifically, the light absorbing particles are dispersed in a binder having a refractive index of Nr. The refractive index Nr is lower than the refractive index Nt of the light transmitting portion 13. In this way, by making the refractive index of the light absorbing unit 14 smaller than the refractive index of the light transmitting unit 13, the light incident on the light transmitting unit 13 under predetermined conditions is appropriately totally reflected at the interface with the light absorbing unit 14. Can be made to. Further, even if the total reflection condition is not satisfied, some light is reflected at the interface.
The value of the refractive index Nr is not particularly limited, but is preferably 1.50 or less from the viewpoint of appropriately performing the total reflection, and more preferably 1.47 or more from the viewpoint of availability. More preferably, it is 1.49 or more.

The difference in the refractive index between the refractive index Nt of the light transmitting unit 13 and the refractive index Nr of the light absorbing unit 14 is not particularly limited, but it is preferable that Nt—Nr is 0 or more and 0.14 or less. However, when making a difference in refractive index, it is preferable that Nt-Nr is 0.05 or more and 0.14 or less. By increasing the difference in refractive index, more light can be totally reflected. Further, even when Nt <Nr, it is possible to reflect light.

In order to prevent the ghost from being visually recognized by the observer, it is originally desirable that there is no difference in the refractive index between Nt and Nr. However, in reality, the refractive index of the material molded and cured first and the refractive index of the material filled and cured later are usually different and therefore do not match. Therefore, the present invention makes it possible to prevent the observer from visually recognizing the ghost even when there is a difference in the refractive index.

The optical functional layer 12 is not particularly limited, but for example, the light transmitting portion 13 and the light absorbing portion 14 are formed as follows. That is, the pitch of the light transmitting portion 13 and the light absorbing portion 14 represented by _Pk in FIG. 4 is preferably 30 μm or more and 100 μm or less. Further, the angle formed by the interface between the light absorbing portion 14 and the light transmitting portion 13 shown by θ _k in FIG. 4 and the normal of the layer surface of the optical functional layer 12 shall be 1 ° or more and 10 ° or less. Is preferable. The thickness of the light absorbing portion 14 shown by _Dk in FIG. 4 is preferably 60 μm or more and 150 μm or less. By setting it within these ranges, the balance between light transmission and light absorption can be made appropriate.

In this embodiment, an example is shown in which the interface between the light transmitting portion 13 and the light absorbing portion 14 is linear in the cross section, but the present invention is not limited to this, and is not limited to this, such as a polygonal line, a convex curved surface, a concave curved surface, and a multi-stage shape. It may be. Further, the plurality of light transmitting portions 13 and the light absorbing portions 14 may have the same cross-sectional shape, or may have different cross-sectional shapes with predetermined regularity. That is, the width of the light transmitting portion may be wide on the display light emitting portion side and narrow on the observer side.
Here, the “width of the light transmitting portion” represents the distance from one interface between the light transmitting portion and the light absorbing portion to the other interface, as shown by _Wc in FIG. 4, and the distance thereof. Is the distance along the direction in which the light transmitting portion and the light absorbing portion are arranged, that is, the distance in the pitch direction.
Further, in the present embodiment, the pitch interval may be a different distance for each pitch.

The optical sheet 10 can be manufactured, for example, as follows.
First, the light transmitting portion 13 is formed on the base material layer 11. This inserts a base material sheet to be a base material layer 11 between a mold roll having a shape on the surface on which the shape of the light transmitting portion 13 can be transferred and a nip roll arranged so as to face the mold roll. At this time, the mold roll and the nip roll are rotated while supplying the composition constituting the light transmitting portion between the base sheet and the mold roll. As a result, the groove corresponding to the light transmitting portion (the shape obtained by reversing the shape of the light transmitting portion) formed on the surface of the mold roll is filled with the composition constituting the light transmitting portion, and the composition is formed on the surface of the mold roll. It follows the shape.

Here, examples of the composition constituting the light transmitting portion include ionizing radiation curable resins such as epoxy acrylate-based, urethane acrylate-based, polyether acrylate-based, polyester acrylate-based, and polythiol-based resins.

The composition sandwiched between the mold roll and the base sheet and constituting the light transmitting portion filled therein is irradiated with light for curing by a light irradiation device from the base sheet side. Thereby, the composition can be cured and its shape can be fixed. Then, the base material layer 11 and the molded light transmitting portion 13 are released from the mold roll by the mold release roll.

Next, the light absorption unit 14 is formed. The method for producing the light absorbing portion is not particularly limited, but the method for producing the light absorbing portion will be described below by wiping.
In order to form the light absorbing portion 14, first, the composition constituting the light absorbing portion is filled in the space between the formed light transmitting portions 13. Then, the excess composition is scraped off with a doctor blade or the like. Then, the remaining composition is irradiated with light from the light transmitting portion 13 side by a light irradiating device to cure the composition and fix its shape. In this way, the light absorption unit 14 can be formed.

The material used as the light absorbing portion is not particularly limited, but is colored in a photocurable resin such as urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, and butadiene (meth) acrylate. Examples thereof include compositions in which the light absorbing particles are dispersed.

Further, instead of dispersing the light absorbing particles, the entire light absorbing portion can be colored with a pigment or a dye.
When light absorbing particles are used, light absorbing colored particles such as carbon black are preferably used, but the present invention is not limited to these, and a specific wavelength is selectively absorbed according to the characteristics of the image light. Colored particles may be used. Specific examples thereof include organic fine particles colored with metal salts such as carbon black, graphite and black iron oxide, dyes and pigments, and colored glass beads. In particular, colored organic fine particles are preferably used from the viewpoints of cost, quality, availability, and the like. On the other hand, when colored organic fine particles or glass beads are used, light may be reflected even if there is a difference in refractive index with the binder. Therefore, from the viewpoint of suppressing ghost generation, the carbon black pigment itself absorbs light. It is preferable to disperse the particles as particles in a binder. Therefore, in Examples 3 and 4, only carbon black particles are dispersed as light absorbing particles in a transparent binder.
When colored organic fine particles or glass beads are used as the light absorbing particles, the average particle diameter is preferably 1 μm or more and 20 μm or less. On the other hand, when carbon black particles are used as the light absorbing particles, the average particle diameter is preferably 10 nm or more and 500 nm or less. As described above, the size of the colored particles and the like can be appropriately selected depending on the size of the light absorbing portion.
Here, the "average particle diameter" means the diameter obtained by observing 100 light absorbing particles with an electron microscope, measuring the diameter, and arithmetically averaging the diameter.

As a result, the optical sheet 10 in which the optical functional layer 12 is laminated on the surface of the base material layer 11 on the observer side is produced.

Further, in the optical functional layer 12, a protective layer can be provided on the surface opposite to the base material layer 11, that is, the surface on the observer side. The method of laminating the protective layer on the optical functional layer 12 can be laminating using a roll, a UV adhesive, or the like.

The panel 20 is a plate-shaped member that transmits light, and the material thereof can be used without particular limitation as long as it transmits light. For example, glass, a transparent resin, or the like can be exemplified.
As can be seen from FIGS. 2 and 3, the panel 20 is arranged closer to the observer than the optical sheet 10. The panel 20 may be laminated or adhered to the optical sheet 10.

The display light emitting unit 120 of this embodiment is an instrument such as a speedometer or a tachometer, and includes a meter needle and an indicator. However, the display light emitting unit according to the present invention is not limited to this form, and for example, a known surface light source device or the like and a liquid crystal panel can be used for the display light emitting unit. That is, the present invention also includes a display light emitting unit including a surface light source device and a liquid crystal panel, and it is also possible to combine this with an optical sheet to form a liquid crystal display device.

Next, the operation of the display device having the above configuration will be described with reference to an optical path example. However, the optical path example is conceptual for explanation, and does not strictly represent the degree of reflection or refraction.

This will be described with reference to FIG.
The light emitted from the display light emitting unit 120 goes toward the optical sheet 10, passes through the base material layer 11, and enters the optical functional layer 12. The light incident on the optical functional layer 12 travels with the following optical paths. That is, for example, as shown by L31 in FIG. 4, the light transmitting portion 13 is transmitted without reaching the interface with the light absorbing portion 14. Alternatively, as shown by L32 in FIG. 4, it reaches the interface with the light absorbing portion 14 and is totally reflected to pass through the light transmitting portion 13. At this time, in the present embodiment, due to the action of the inclination angle (θ _k ) of the interface, the light reflected at the interface travels in a direction not parallel to the normal of the panel 20. Further, even if the light is not totally reflected because the angle is smaller than the total reflection critical angle, some of the light is reflected at the interface. Such light also passes through the light transmitting portion 13.

On the other hand, as shown by L33 in FIG. 4, external light incident on the optical functional layer 12 from the observer side at a large angle with respect to the sheet surface normal is absorbed by the light absorbing unit 14, and a decrease in contrast can be prevented.

Therefore, when the observer is in front of the display device, the observer can visually recognize only the image obtained from the L31. Therefore, the display device according to the present invention can absorb external light and prevent the ghost from being visually recognized from the front.

In the above-described embodiment, the optical functional layer 12 has the short upper base of the light transmitting portion 13 facing the observer side and the long lower base facing the display light emitting portion side, but in the inverted form of the present invention. Does not work. That is, as shown in FIG. 5, when the short upper base of the light transmitting portion faces the display light emitting portion side and the long lower base faces the observer side, the ghost tends to be easily visible from the front.

The light emitted from the display light emitting unit 120 faces the optical sheet 10 and is incident on the optical functional layer 12. The light incident on the optical functional layer 12 travels with the following optical paths. That is, for example, the light shown by L31'in FIG. 5 passes through the light transmitting portion 13 and the base material layer 11 without reaching the interface with the light absorbing portion 14, as in the case of L31 in FIG. On the other hand, the light shown by L32'in FIG. 5 reaches the interface with the light absorbing portion 14, is totally reflected, and is transmitted through the light transmitting portion 13 and the base material layer 11. At this time, the light reflected at the interface travels in a direction parallel to the normal of the panel 20. Further, even if the light is not totally reflected because the angle is smaller than the total reflection critical angle, some of the light is reflected at the interface. Such light also passes through the light transmitting portion 13 and the base material layer 11.

That is, when the observer is in front of the display device according to FIG. 5, the observer may visually recognize the image (main image) obtained from L31'and the image (ghost) obtained from L32'. .. Therefore, when a display device as shown in FIG. 5 is used, an observer facing the front tends to easily see the ghost.

Next, another embodiment of the present invention will be described with reference to FIG. FIG. 6 is a diagram illustrating a form in which the interface between the light transmitting portion and the light absorbing portion is a polygonal line in a cross section in the optical sheet described in FIG. By taking such a form, it is possible to guide the light to be a ghost back to the display light emitting portion side and suppress the ghost from being visually recognized by the observer. In the following, items that overlap with the description of FIG. 4 are omitted.

The optical sheet 40 shown in FIG. 6 includes a base material 11 and an optical functional layer 42, and the optical functional layer 42 includes a light transmitting portion 43 and a light absorbing portion 44. The interface between the light transmitting portion 43 and the light absorbing portion 44 has a polygonal shape, extends in one direction along the surface of the base material layer 11, and is arranged in a direction different from the extending direction at predetermined intervals. .. The light absorbing portions 44 are formed at intervals of adjacent light transmitting portions 43.

It will be described that the ghost is not visually recognized by the observer by the action of the optical sheet 40 in FIG. The light emitted from the display light emitting unit 120 takes the next optical path. As shown in L51, it transmits the base material layer 11 and transmits the light transmitting portion 43 without reaching the interface with the light absorbing portion 44. On the other hand, the light that takes an optical path as shown in L52 goes toward the optical sheet 40, passes through the base material layer 11, and enters the optical functional layer 42. Then, when it reaches the interface between the light transmitting portion 43 and the light absorbing portion 44, it proceeds in the following optical path. That is, as shown in L53, the light absorbing portion 44 is once transmitted, reaches the interface between the light transmitting portion 43 and the light absorbing portion 44 again, and is reflected. Then, the reflected light reaches the interface with the other layer, is reflected again, and takes an optical path guided to the display light emitting unit side 120. Further, as shown in L54, the reflected light is reflected at the interface between the light transmitting portion 43 and the light absorbing portion 44, the reflected light reaches the interface with the other layer, is reflected again, and is guided to the display light emitting portion side 120. Take the light path.

In this way, the optical sheet 40 described in FIG. 6 guides the light to be a ghost to the display light emitting portion side, and makes it possible to suppress the ghost from being visually recognized by the observer. Although FIG. 6 has described a form in which the interface between the light transmitting portion and the light absorbing portion has a broken line shape in the cross section, the light transmitting portion of the present invention is not limited to this form, and the light transmitting portion and the light absorbing portion are not limited to this form. The light may be reflected at the interface with the light, and the reflected light may be reflected again at the interface with the other layer and guided to the display light emitting portion side. For example, the light transmitting portion may have a curved cross section. On the other hand, when the light transmitting portion has a polygon in the cross section, it is preferably a polygon of hexagon or more. Further, although it has been described above that the ghost light is reflected again at the interface between the optical functional layer and the other layer and guided to the display light emitting portion side, the present invention is not limited to this embodiment. For example, a new layer may be provided between the optical sheet and the panel, and the layer may be reflected again at the interface of the layer and guided to the display light emitting portion side.

The display devices according to Examples 1 to 4 and Comparative Examples 1 and 2 were produced, and whether or not the ghost was visually recognized was evaluated.

(Example 1)
In Example 1, according to the example of the optical sheet of FIG. 4, the short upper base of the light transmitting portion faces the observer side, and the long lower base faces the display light emitting portion side. Specifically, it is as follows.

An optical sheet was prepared using a polycarbonate resin having a thickness of 130 μm as the base material layer. First, a light transmitting portion was formed on the surface of the base material layer on the observer side. At this time, an ultraviolet curable urethane acrylate having a refractive index of 1.56 is used as the light transmitting portion, the cross section of the light transmitting portion is isosceles trapezoidal, the pitch ( _{Pk in} FIG. 4) is 85 μm, the upper bottom is 30 μm, and the lower part. The bottom was 55 μm, the height was 150 μm, and the land thickness was 25 μm. Further, the haze of the surface of the light transmitting portion on the observer side was 20.
Next, the light absorbing portion was formed by wiping. In the light absorbing part, the binder was an ultraviolet curable urethane acrylate having a refractive index of 1.49, and 25% by mass of acrylic beads having an average particle diameter of 4 μm containing carbon black was contained therein. The cross section of the light absorbing portion is an isosceles trapezoid, the upper base (W _{a in} FIG. 4) is 30 μm, the lower base (W _{b in} FIG. 4) is 55 μm, and the height (D _{k in} FIG. 4) is 150 μm. ..

Further, an ultraviolet curable urethane acrylate was laminated with a mat roll on the surface of the optical functional layer on the observer side as a protective layer. At this time, the haze of the surface of the protective layer on the observer side was 30. From the above, an optical sheet was produced.

Such an optical sheet was attached to a 6.5-inch liquid crystal display device (LQ65T5GG03 manufactured by Sharp Corporation) to form a display device. More specifically, display emission consisting of a light guide plate having a light emitting source arranged on the side surface, a prism sheet, a light diffusing film, a surface light source device including a reflective polarizing plate, and a liquid crystal panel arranged on the light emitting surface side thereof. The unit was arranged, and an optical sheet was further arranged on the observer side of the display light emitting unit. At this time, the short upper base of the light transmitting portion faces the observer side, and the long lower base faces the display light emitting portion side.

To evaluate whether or not the ghost is visible, the optical functional layer is moved so as to continuously change the distance between the optical functional layer and the display light emitting portion from 5 mm to 50 mm. evaluated. Specifically, at this time, the observer visually observed from the front of the display device and determined whether or not the ghost was visually recognized.

(Example 2)
The second embodiment is a display device in which a 100 μm polycarbonate film is laminated with a UV adhesive in the protective layer of the optical sheet according to the first embodiment.

(Example 3)
Example 3 is a display device in which 5% by mass of carbon black particles having an average particle diameter of 100 nm are contained in place of acrylic beads in the optical sheet according to Example 1.

(Example 4)
Example 4 is a display device in which 5% by mass of carbon black particles having an average particle diameter of 100 nm are contained in place of acrylic beads in the optical sheet according to Example 2.

(Comparative Example 1)
The display device according to Comparative Example 1 is a display device in which the optical sheet is arranged so that the short upper bottom of the light transmitting portion faces the display light emitting portion side and the long lower bottom faces the observer side in the display device according to the first embodiment. is there.

(Comparative Example 2)
The display device according to Comparative Example 2 is a display device in which the optical sheet is arranged so that the short upper bottom of the light transmitting portion faces the display light emitting portion side and the long lower bottom faces the observer side in the display device according to the second embodiment. is there.

As a result, in the display devices according to Examples 1 and 2, the ghost was not visually recognized by the observer from the front view. However, when the observation direction was changed to 20 ° up and down, the ghost was visually recognized. In the display devices according to Examples 3 and 4, ghosts were not visually recognized even when the observation direction was front view or an angle of 20 ° up and down. It is considered that this is because the carbon black particles contained in the light absorbing portion partially absorbed the light from the display light emitting portion, so that the ghost light became so weak that it could not be visually recognized.
On the other hand, in the display devices according to Comparative Examples 1 and 2, ghosts were visually recognized even when viewed from the front of the observer.

10, 40 Optical sheet 11 Base material layer 12, 42 Optical functional layer 13, 43 Light transmitting unit 14, 44 Light absorbing unit 20 Panel 100 Display device 110 Panel unit 120 Display light emitting unit 130 Housing

Claims (6)

The display and light emitting part, which is an instrument of an automobile,
An optical sheet arranged on the observer side from the display light emitting unit and
It is a display device equipped with
The optical sheet includes a base material layer and an optical functional layer, and has an optical functional layer.
The optical functional layer is
A light transmitting portion having a predetermined cross section, extending in one direction along the surface of the base material layer, and being arranged in a direction different from the extending direction at predetermined intervals.
A light absorbing portion formed at the distance between adjacent light transmitting portions is provided.
The width of the light transmitting portion is wide on the display light emitting portion side and narrow on the observer side.
The optical functional layer has a distance of 5 mm or more and 50 mm or less from the display light emitting portion, and the optical sheet is arranged so as not to touch the display light emitting portion .
The interface between the light transmitting portion and the light absorbing portion has a polygonal shape or a curve, and light is reflected at the interface between the light transmitting portion and the light absorbing portion, and further adjacent to the optical functional layer. as the light reflected again at the interface between the layer back to the display light-emitting portion, the light-transmitting portion and the light absorbing portion is configured,
Display device. The display device according to claim 1, wherein when the refractive index of the light transmitting portion is Nt and the refractive index of the light absorbing portion is Nr, Nt—Nr exceeds 0. The display device according to claim 1, wherein when the refractive index of the light transmitting portion is Nt and the refractive index of the light absorbing portion is Nr, Nt-Nr is 0. The display device according to claim 1 , wherein the other layer is a protective layer. The display device according to any one of claims 1 to 4 , further comprising a panel arranged on the observer side of the optical sheet, wherein the panel is a plate-shaped member that transmits light. A liquid crystal display device comprising the display device according to any one of claims 1 to 5 , wherein the display device includes a liquid crystal panel in the display light emitting unit.