Optical sheet, surface light source device and display device

Abstract

To provide an optical sheet that can provide a display device capable of controlling emission of image light in the vertical and horizontal directions. [Solution] An optical sheet comprising a base layer 1 and an optical functional layer 2 laminated on one side of the base layer, wherein the optical sheet has a rectangular shape in a plan view with a pair of first sides extending in a first direction and a pair of second sides extending in a second direction, and the optical functional layer has a plurality of light-transmitting sections 3 having a predetermined cross-section and extending in one direction, and light-absorbing sections 4 formed between adjacent light-transmitting sections, wherein the predetermined cross-section of the light-transmitting sections is trapezoidal and the shorter upper base is the light incident side, and when the light transmittance in a third direction perpendicular to the first and second directions is taken as 100%, the relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±20° toward the first direction with respect to the third direction, is 10% or less, and the extension direction of the light-transmitting sections has an angle of 1.5° or more and 20° or less with respect to the second direction.

Description

[Technical field]

[0001] The present disclosure relates to an optical sheet, a surface light source device, and a display device. [Background technology]

[0002] Display devices such as televisions and computer monitors include an image source that emits an image to be displayed, and also include an optical sheet that improves the quality of the image light and provides it to the observer (for example, Patent Documents 1 to 3).

[0003] The emission direction of the image light is often set to the front and a viewing angle of a certain angle up, down, left, and right from the front. This allows the image projected on the screen to be viewed not only from the front, but also from positions at a certain angle. On the other hand, in order to prevent peeping, etc., the main emission direction is set to the front direction and the viewing angle is restricted as necessary. An optical sheet for this purpose is disclosed in Patent Document 4, for example. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-080198 A [Patent Document 2] JP 2015-014681 A [Patent Document 3] JP 2017-215440 A [Patent Document 4] JP 2006-171701 A Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, a display device for the purpose of entertainment for the person sitting in the passenger seat may be placed in front of the passenger seat of a vehicle such as an automobile. In such a passenger seat display device, it is required to control the emission of image light to the driver's side so as not to disturb the driver's driving. However, when a conventional optical sheet is mounted on a passenger seat display device, when the light transmittance (%) at the front is 100%, for example, the relative transmittance, which is the ratio of the light transmittance (%) in a direction inclined at ±30° to the left and right from the front, is about 10%, and the relative transmittance, which is the ratio of the light transmittance (%) in a direction inclined at ±20° to the left and right from the front, is about 55%, and the light output is visible on the driver's side. In addition, in the case of a right-hand drive vehicle, the passenger seat display device is generally placed in a direction inclined at least 20° to 30° to the left with respect to the front direction of the driver. Similarly, in the case of a left-hand drive vehicle, the passenger seat display device is generally placed in a direction inclined at least 20° to 30° to the right with respect to the front direction of the driver.

[0006] FIG. 11(a) shows a schematic perspective view of a conventional optical sheet. The optical sheet 90 shown in FIG. 11(a) extends along one side direction of the sheet (second direction D2 in FIG. 11(a)), and has a layer (optical function layer 32) in which light transmitting parts (light transmitting parts 33) and light absorbing parts (light absorbing parts 34) are alternately arranged in parallel along the sheet surface. Such an optical sheet controls the viewing angle only in the direction perpendicular to the extension direction (second direction D2 in FIG. 11(a)) of the light transmitting parts 33 and the light absorbing parts 34 (first direction D1 in FIG. 11(a)), and it is difficult to control the viewing angle in the parallel direction (second direction D2 in FIG. 11(a)). Therefore, as shown in FIG. 11(b), when the optical sheet 90 is used in a passenger seat display device 100, image light may be reflected on the passenger seat side of the windshield of the car. Therefore, it is necessary to control the reflection (in the vertical direction) on the windshield in front of the passenger seat as well. Note that, in Fig. 11(b), members of the display device 100 other than the optical sheets are omitted.

[0007] The present disclosure has been made in consideration of the above circumstances, and aims to provide an optical sheet that can provide a display device capable of controlling the emission of image light in the vertical and horizontal directions. Specifically, the present disclosure aims to provide an optical sheet that, when used as an optical sheet for a display device disposed in front of the passenger seat of a vehicle, can provide a display device capable of controlling the emission of image light to the driver's side and controlling the reflection of the image light on the windshield in front of the passenger seat. [Means for solving the problem]

[0008] One embodiment of the present disclosure is an optical sheet comprising a base layer and an optical functional layer laminated on one side of the base layer, wherein the optical sheet has a rectangular shape in a plan view having a pair of first sides extending in a first direction and a pair of second sides extending in a second direction, the optical functional layer has a plurality of light-transmitting sections having a predetermined cross-section and extending in one direction, and light-absorbing sections formed between adjacent light-transmitting sections, wherein the predetermined cross-section of the light-transmitting sections is trapezoidal and has a shorter upper base as the light entrance side, a relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±20° toward the first direction with respect to the third direction when the light transmittance in a third direction perpendicular to the first direction and the second direction is set to 100%, is 10% or less, and the extension direction of the light-transmitting sections has an angle of 1.5° or more and 20° or less with respect to the second direction.

[0009] Another embodiment of the present disclosure is an optical sheet comprising a base layer and an optical functional layer laminated on one side of the base layer, wherein the base layer is a resin base material, and the optical sheet has a rectangular shape in a plan view having a pair of first sides extending in a first direction and a pair of second sides extending in a second direction, the optical functional layer has a plurality of light-transmitting portions having a predetermined cross-section and extending in one direction, and light-absorbing portions formed between adjacent light-transmitting portions, wherein the predetermined cross-section of the light-transmitting portions is trapezoidal and a shorter upper base is the light-entering side, and the optical sheet is an optical sheet for a display device disposed in front of a passenger seat of a vehicle, and an extension direction of the light-transmitting portions has an angle of 1.5° or more and 20° or less with respect to the second direction.

[0010] Another embodiment of the present disclosure is a surface light source device including the above-mentioned optical sheet and a light source that emits light incident on the optical sheet.

[0011] Another embodiment of the present disclosure is a display device including the above-mentioned surface light source device and a display panel laminated on the surface light source device.

[0012] Another embodiment of the present disclosure is a display device comprising an optical sheet and a display panel, the optical sheet comprising a base layer and an optical functional layer laminated on one side of the base layer, the optical functional layer having a plurality of light-transmitting portions having a predetermined cross-section and extending in one direction, and light-absorbing portions formed between adjacent light-transmitting portions, the predetermined cross-section of the light-transmitting portions being trapezoidal with a shorter upper base being the light-entering side, the optical sheet having a relative transmittance of 10% or less when the display device is installed, which is the ratio of the light transmittance in a direction inclined ±20° left and right from the normal direction of the main surface of the optical sheet when the light transmittance in the normal direction of the main surface of the optical sheet is 100%, and the extension direction of the light-transmitting portions as viewed from the normal direction has an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0013] Another embodiment of the present disclosure is a display device comprising an optical sheet and a display panel and disposed in front of a passenger seat of a vehicle, wherein the optical sheet comprises a base material layer and an optical functional layer laminated on one side of the base material layer, the base material layer being a resin base material, the optical functional layer having a plurality of light-transmitting portions having a predetermined cross-section and extending in one direction, and light-absorbing portions formed between adjacent light-transmitting portions, the predetermined cross-section of the light-transmitting portions being trapezoidal with a shorter upper base being the light-entering side, and the optical sheet is a display device in which, when the display device is disposed in front of the passenger seat of a vehicle, the extension direction of the light-transmitting portions as viewed from the normal direction of the main surface of the optical sheet has an angle of 1.5° or more and 20° or less with respect to the vertical direction. Effect of the Invention

[0014] In the present disclosure, an optical sheet can be provided that can provide a display device capable of controlling emission of image light in the vertical and horizontal directions. Furthermore, in the present disclosure, an optical sheet can be provided that can provide a display device capable of controlling emission of image light to the driver's side and controlling reflection of the image light on the windshield in front of the passenger seat when used as an optical sheet for a display device disposed in front of the passenger seat of a vehicle. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic perspective view illustrating an optical sheet according to the present disclosure. [Diagram 2] 1 is a schematic cross-sectional view illustrating an optical sheet according to the present disclosure. [Diagram 3] 1 is a schematic plan view illustrating an optical sheet according to the present disclosure. [Figure 4] 1 is a schematic cross-sectional view illustrating an optical sheet according to the present disclosure; [Diagram 5] 1 is an exploded perspective view illustrating a display device according to the present disclosure. [Figure 6] 1 is a portion of an exploded cross-sectional view illustrating a display device of the present disclosure. [Figure 7] 1 is a portion of an exploded cross-sectional view illustrating a display device of the present disclosure. [Figure 8]1A and 1B are a schematic diagram of the front interior of a vehicle in which a display device according to the present disclosure is arranged as a display device for a passenger seat, and a front view of the display device. [Figure 9] 1 is a portion of an exploded cross-sectional view illustrating a display device of the present disclosure. [Figure 10] 1 is a schematic cross-sectional view illustrating an optical sheet according to the present disclosure. [Figure 11] 1A and 1B are a schematic perspective view of a conventional optical sheet and a schematic view of the front interior of a vehicle in which the optical sheet is arranged as a display device for a passenger seat. [Figure 12] 1 shows the results of measuring the relative transmittance (left and right direction) of the optical sheets of Example 4 and Comparative Example 8, and an observation diagram of a display device including the optical sheets of Example 4 and Comparative Example 8. FIG. [Figure 13] 1 shows the results of measuring the relative transmittance (vertical direction) of the optical sheets of Example 4 and Comparative Example 8, and an observation diagram of a display device including the optical sheets of Example 4 and Comparative Example 8. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The following describes the embodiments of the present disclosure with reference to the drawings. However, the present disclosure can be implemented in many different forms, and is not to be construed as being limited to the description of the embodiments exemplified below. In addition, the drawings may be schematic in terms of the width, thickness, shape, etc. of each part compared to the actual form in order to make the explanation clearer, but these are merely examples and do not limit the interpretation of the present disclosure. In addition, in this specification and each figure, elements similar to those described above with respect to the previous figures may be given the same reference numerals, and detailed explanations may be omitted as appropriate.

[0017] In this specification, when describing an aspect in which another component is disposed on a certain component, the term "above" or "below" includes both cases in which another component is disposed directly above or below a certain component so as to be in contact with the component, and cases in which another component is disposed above or below a certain component with another component interposed therebetween, unless otherwise specified. In addition, in this specification, when describing an aspect in which another component is disposed on the surface of a certain component, the term "on the surface side" or "on the surface" includes both cases in which another component is disposed directly above or below a certain component so as to be in contact with the component, and cases in which another component is disposed above or below a certain component with another component interposed therebetween, unless otherwise specified.

[0018] The optical sheet, surface light source device, and display device of the present disclosure will be described in detail below.

[0019] A-1. Optical sheet (first embodiment) The optical sheet of this embodiment is an optical sheet comprising a base layer and an optical functional layer laminated on one surface of the base layer, wherein the optical sheet has a rectangular shape in a plan view having a pair of first sides extending in a first direction and a pair of second sides extending in a second direction, the optical functional layer has a plurality of light-transmitting sections having a predetermined cross-section and extending in one direction, and light-absorbing sections formed between adjacent light-transmitting sections, wherein the predetermined cross-section of the light-transmitting sections is trapezoidal and the shorter upper base is the light-entering side, a relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±30° toward the first direction with respect to the third direction when the light transmittance in a third direction perpendicular to the first direction and the second direction is 100%, is 1% or less, and the extension direction of the light-transmitting sections has an angle of 1.5° or more and 20° or less with respect to the second direction.

[0020] The optical sheet of the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic perspective view showing an example of the optical sheet of the present embodiment. FIG. 2 shows a cross-sectional view of the optical sheet cut along the line II in FIG. 1. FIG. 3 is a plan view of the optical sheet shown in FIG. 1, seen along the direction from the base layer 1 to the optical functional layer 2 (-D3 direction). FIG. 4 is an enlarged cross-sectional view of the optical sheet shown in FIG. 2. In the third direction D3, the direction from the optical functional layer 2 to the base layer 1 is the +D3 direction, and the direction from the base layer 1 to the optical functional layer 2 is the -D3 direction. In FIGS. 1 to 3, the directions (vertical and horizontal directions) in the posture in which the display device is installed when the optical sheet is used in the display device are also shown, but the installation posture is not limited to this. For example, when the optical sheet is used in the display device, the display device is preferably arranged in a posture in which the first direction D1 is horizontal and the second direction D2 is vertical, as shown in FIG. 1, but is not limited to this posture. Each member will be described below.

[0021] 1 to 4, the optical sheet 10A of this embodiment includes a sheet-shaped base layer 1 and an optical functional layer 2 provided on one surface of the base layer 1. The base layer 1 and the optical functional layer 2 are laminated along a third direction D3. As shown in Fig. 3, the optical sheet 10A of this embodiment has a rectangular shape in plan view having a pair of first sides L1 extending in the first direction D1 and a pair of second sides L2 extending in the second direction D2.

[0022] The optical function layer 2 has a plurality of light transmitting parts 3 having a predetermined cross section and extending in one direction, and a light absorbing part 4 formed between adjacent light transmitting parts 3. As shown in FIG. 2, the cross section of the light transmitting part 3 cut on the D1-D3 plane is a trapezoid, and the shorter upper base is the light incident side (light source side). In this embodiment, as shown in FIG. 2, when the light transmittance in the third direction D3 is 100%, the relative transmittance, which is the ratio of the light transmittance in a direction inclined ±30° toward the first direction D1 side with respect to the third direction D3, is 1% or less. Furthermore, as shown in FIG. 3, the extension direction of the light transmitting part 3 has an angle θ of 1.5° or more and 20° or less with respect to the second direction D2.

[0023] According to the optical sheet 10A of the present embodiment, when the light transmittance in the third direction D3 is 100%, the relative transmittance, which is the ratio of the light transmittance in the direction inclined by ±30° toward the first direction side with respect to the third direction D3, is equal to or less than a predetermined value, so that it is possible to control the light output angle in the first direction D1. Furthermore, in a state in which the light output angle in the first direction D1 is controlled, the extension direction of the light transmitting portion 3 has an angle θ of 1.5° or more and 20° or less with respect to the second direction D2, so that it is possible to control the light output angle in the second direction D2. This is because the viewing angle in the first direction D1 has a very narrow characteristic, and when the viewing angle is set to an angle θ of 1.5° or more and 20° or less while maintaining that state, the light transmittance in the second direction D2 is rapidly reduced.

[0024] Therefore, when the optical sheet of the present embodiment is used in a display device, it is possible to control the light emission angle in the left-right direction and the up-down direction of the display device. More specifically, when the optical sheet is used as an optical sheet for a display device disposed in front of the passenger seat of a car, it is possible to control the emission of image light to the driver's side, and also possible to control the reflection of the image light on the windshield in front of the passenger seat.

[0025] For example, it is conceivable to control the light output angle in the first direction D1 while controlling the light output angle in the second direction D2 by stacking two conventional optical sheets 90 shown in Fig. 11 in orthogonal directions. However, this method reduces the light transmittance and decreases the brightness of the display device.

[0026] In contrast, optical sheet 10A of the present embodiment makes it possible to control the light output angle in the first direction D1 and the light output angle in the second direction D2 with a single sheet, thereby suppressing a decrease in light transmittance.

[0027] 1.Optical functional layer The optical sheet in this embodiment includes a base layer and an optical functional layer laminated on one surface of the base layer, and is disposed such that, when the optical sheet is used in a display device, the optical functional layer faces the light source and the base layer faces the viewer.

[0028] As shown in Fig. 1, the optical functional layer 2 is a layer laminated on one surface of the base layer 1, and light-transmitting portions 3 and light-absorbing portions 4 are alternately arranged in a first direction D1 along the layer surface. In the cross section shown in Fig. 2, the optical functional layer 2 includes a substantially trapezoidal light-transmitting portion 3 and a substantially trapezoidal cross-section light-absorbing portion 4 formed between two adjacent light-transmitting portions 3. Light that enters the optical sheet 10A enters the optical functional layer 2 from a light-entering surface Pin, and exits from a light-exiting surface Pout except for a portion of the light.

[0029] FIG. 4 is an enlarged view of the cross-sectional view shown in FIG. 2. As shown in FIG. 4, the light La that enters the light transmitting portion 3 of the optical functional layer 2 vertically at an incident angle of 0° passes through the inside of the light transmitting portion 3 and is output from the light output surface Pout. Although not shown, the light that enters the light absorbing portion 4 of the optical functional layer 2 vertically at an incident angle of 0° is absorbed by the light absorbing portion 4 and is blocked by the optical functional layer 2. Of the light that enters the light transmitting portion 3 of the optical functional layer 2 obliquely at an incident angle greater than 0°, the light Lb that enters near the boundary with the light absorbing portion 4 travels obliquely inside the light transmitting portion 3 and is output from the light output surface Pout without being blocked by the light absorbing portion 4 adjacent to the light absorbing portion 4. Therefore, the light that enters the light transmitting portion 3 at an angle greater than the incident angle of this light Lb is blocked by the light absorbing portion 4, and as a result, the light that enters the optical functional layer 2 as a whole is controlled.

[0030] Of the light that enters the light-transmitting portion 3 of the optical functional layer 2 at an angle of incidence greater than 0° at an angle, at least a part of the light Lc that travels obliquely inside the light-transmitting portion 3 and reaches the side surface of the light-absorbing portion 4 is reflected by the side surface of the light-absorbing portion 4, changes its traveling direction to the front direction, is collected, and passes through the light-transmitting portion 3. At this time, if the refractive index of the light-absorbing portion 4 is set smaller than the refractive index of the light-transmitting portion 3, the light Lc that reaches the side surface of the light-absorbing portion 4 at an incident angle equal to or greater than the critical angle is totally reflected without being absorbed by the light-absorbing portion 4. For this reason, the light transmittance is improved by the total reflection effect.

[0031] Of the light that enters the light-transmitting section 3 of the optical functional layer 2 at an oblique angle of incidence greater than 0°, the light Ld that travels obliquely inside the light-transmitting section 3 and reaches the side surface of the light-absorbing section 4 at a smaller angle of incidence with respect to the side surface than the light Lc is reflected by the side surface of the light-absorbing section 4, but only a portion of it is reflected; the rest is absorbed by the light-absorbing section 4.

[0032] The light transmitting portions 3 are portions whose main function is to transmit light, and are elements having a generally trapezoidal cross-sectional shape with a long lower base on the base layer 1 side and a short upper base on the opposite side, as shown in Fig. 2. The light transmitting portions 3 extend in one direction (a direction forming an angle θ with respect to the second direction D2) while maintaining the cross-section along the layer surface of the base layer 1, and are arranged at predetermined intervals in a direction (first direction D1) different from the extending direction.

[0033] In the optical sheet of the present embodiment, the relative transmittance, which is the ratio of the light transmittance in a direction tilted by ±30° toward the first direction with respect to the third direction when the light transmittance in the third direction is taken as 100%, is 1% or less. The relative light transmittance is preferably 0.6% or less, and more preferably 0.4% or less.

[0034] The average value of the relative transmittance of light in a direction tilted at -30° and the relative transmittance of light in a direction tilted at +30° is defined as the "relative transmittance of light in a direction tilted at ±30°."

[0035] The relative transmittance, which is the ratio of the light transmittance in a direction tilted by ±30° toward the first direction with respect to the third direction when the light transmittance in the third direction is taken as 100%, is determined by the following method.

[0036] (Measurement method) First, the optical sheet is not placed, and the luminance of the light in the third direction D3 of the surface light source alone is measured by a viewing angle characteristic measuring device. An edge-light type surface light source using an LED as a light source is used as the surface light source. Next, a surface light source is placed on the back side (optical functional layer side) of the optical sheet, and the luminance of the light transmitted in the third direction D3 of the optical sheet and the luminance of the light transmitted in a direction inclined ±30° toward the first direction D1 side with respect to the third direction D3 are measured on the front side (base layer side) of the optical sheet by a viewing angle characteristic measuring device. Next, the ratio of the luminance of the light transmitted in the third direction D3 of the optical sheet to the luminance of the light in the third direction D3 of the surface light source alone is calculated as the transmittance of the light transmitted in the third direction D3 of the optical sheet. Similarly, the ratio of the luminance of the light transmitted in a direction inclined ±30° toward the first direction D1 side with respect to the third direction D3 to the luminance of the light in the third direction D3 of the surface light source alone is calculated as the transmittance of the light transmitted in a direction inclined ±30° toward the first direction with respect to the third direction. Finally, the relative transmittance is calculated, which is the ratio of the transmittance of light passing through the optical sheet in a direction inclined by ±30° toward the first direction D1 with respect to the third direction D3, when the transmittance of light passing through the optical sheet in the third direction D3 is taken as 100%.

[0037] Transmittance T0 (%) of light transmitted through the optical sheet in the third direction D3 = {(brightness of light emitted from the optical sheet in the third direction D3) / (brightness of light from the surface light source in the third direction D3)} × 100 (%) The transmittance T of light transmitted in a direction inclined by ±30° toward the first direction D1 with respect to the third direction D3 30 ((%)={(brightness of light emitted from the optical sheet in a direction inclined by ±30° toward the first direction D1 with respect to the third direction D3) / (brightness of light in the third direction D3 of the surface light source)}×100(%) ·Relative transmittance (%)=(T 30 / T0)×100(%)

[0038] An optical sheet having such optical properties can be obtained by adjusting one or more of the cross-sectional shapes of the light absorbing portions and the light transmitting portions, the refractive indices of the light absorbing portions and the light transmitting portions, the aperture ratio on the light entrance side, the height of the light absorbing portions, the OD value of the light absorbing portions, etc.

[0039] In this embodiment, the optical sheet has a relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±20° toward the first direction from the third direction to the light transmittance in the third direction being 100%, of preferably 10% or less, and more preferably 5% or less.

[0040] The average value of the relative transmittance of light in a direction tilted at -20° and the relative transmittance of light in a direction tilted at +20° is defined as the "relative transmittance of light in a direction tilted at ±20°."

[0041] The relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±20° toward the first direction from the third direction when the light transmittance in the third direction is taken as 100%, can be determined in the same manner as the relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±30° toward the first direction from the third direction when the light transmittance in the third direction is taken as 100%.

[0042] Furthermore, the optical sheet of this embodiment may have a relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±30° toward the second direction from the third direction when the light transmittance in the third direction is 100%, of 32% or less, 30% or less, or 25% or less.

[0043] The relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±30° toward the second direction from the third direction when the light transmittance in the third direction is taken as 100%, can be determined in the same manner as the relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±30° toward the first direction from the third direction when the light transmittance in the third direction is taken as 100%.

[0044] In this embodiment, the extension direction of the light transmitting portion 3 has an angle θ of 1.5° or more and 20° or less with respect to the second direction D2 in a plan view. The angle θ is 1.5° or more, and may be 5° or more, or 10° or more. Meanwhile, the angle θ may be 20° or less and 15° or less. When the angle θ is in the above range, it is possible to control the light output angle in the second direction. When the display device is installed in a posture as shown in FIG. 1, the right side as viewed from the observer is the +D1 direction, and the left side is the -D1 direction. In FIGS. 1 and 3, the light transmitting portion 3 has an angle θ on the right side (+D1 side) with respect to the second direction D2. In this case, it is preferable that the left side (-D1 side) is the driver's seat side. Meanwhile, the light transmitting portion 3 may have an angle θ on the left side (-D1 side) with respect to the second direction D2. In this case, it is preferable that the right side (+D1 side) is the driver's seat side.

[0045] The angle θ is obtained by the following method. First, as illustrated in FIG. 3, the optical sheet 10 is placed so that the extension direction of the light-transmitting portion 3 is vertical. At this time, it does not matter whether the optical sheet is vertically or horizontally long. Next, the smaller angle between the vertical side (L2) of the optical sheet 10 and the boundary line BL between the light-transmitting portion 3 and the light-absorbing portion 4 is measured. When measuring the angle, the boundary line BL between the light-transmitting portion 3 and the light-absorbing portion 4 on the surface of the short upper base of the light-transmitting portion 3 and the long lower base of the light-absorbing portion 4 of the optical functional layer 2 is used. In addition, as illustrated in FIG. 3, the angle is measured at two points on each of the two vertical sides (L2a, L2b) of the optical sheet 10, and the arithmetic average value of the four measured values ​​is taken as the angle θ.

[0046] Between adjacent light transmitting portions 3, a gap (groove) having a substantially trapezoidal cross section is formed. Therefore, the gap (groove) has a trapezoidal cross section with a long bottom on the top bottom side (opposite the base layer 1 side) of the light transmitting portion 3 and a short top on the bottom bottom side (base layer 1 side) of the light transmitting portion 3, and is filled with a necessary material to be described later to form a light absorbing portion 4. In addition, in Figs. 1 to 4, adjacent light transmitting portions 3 are connected at the long bottom bottom side by a sheet-like connecting portion 2a.

[0047] The light transmitting portion 3 has a refractive index of Nt. Such a light transmitting portion 3 can be formed by curing a composition constituting the light transmitting portion. Details will be described later. The value of the refractive index Nt is not particularly limited, and is, for example, 1.50 or more, and preferably 1.54 or more. On the other hand, the value of the refractive index Nt is, for example, 1.65 or less, and preferably 1.60 or less. Specifically, the value of the refractive index Nt is 1.50 or more and 1.65 or less, and preferably 1.54 or more and 1.60 or less. This is because a refractive index difference with the light absorbing portion described later can be easily obtained.

[0048] The light absorbing portion 4 functions as a gap formed in the above-mentioned gap (groove) formed between adjacent light transmitting portions 3, and has a cross-sectional shape similar to the cross-sectional shape of the gap. Therefore, the short upper base faces the base layer 1, and the long lower base faces the opposite side to the base layer 1. By making the short upper base of the light absorbing portion the light output surface Pout side, a part of the light traveling through the light transmitting portion and reaching the side surface of the light absorbing portion, specifically the interface between the light absorbing portion and the light transmitting portion, is reflected and concentrated in the front direction, thereby improving the light transmittance.

[0049] The light absorbing portion 4 has a refractive index of Nr and is configured to absorb light. Specifically, light absorbing particles are dispersed in a transparent resin having a refractive index of Nr. The refractive index Nr is preferably smaller than the refractive index Nt of the light transmitting portion 3. In this way, by making the refractive index of the light absorbing portion 4 smaller than the refractive index of the light transmitting portion 3, light incident on the light transmitting portion 3 under a specified condition can be appropriately totally reflected at the interface with the light absorbing portion 4. Also, even when the total reflection condition is not satisfied, a part of the light is reflected at the interface.

[0050] The value of the refractive index Nr is not particularly limited, and is, for example, 1.47 or more, and preferably 1.51 or more. On the other hand, the value of the refractive index Nr is, for example, 1.65 or less, and preferably 1.57 or less. Specifically, the value of the refractive index Nr is 1.47 or more and 1.65 or less, and preferably 1.51 or more and 1.57 or less. This is because it is easy to obtain a refractive index difference with the light transmitting portion described later.

[0051] The difference Nt-Nr between the refractive index Nt of the light transmitting portion 3 and the refractive index Nr of the light absorbing portion 4 is not particularly limited, but is preferably 0.05 or less, and more preferably 0.03 or less. The refractive index difference Nt-Nr is, for example, 0 or more. By reducing the refractive index difference, total reflection can be appropriately suppressed and the viewing angle in the first direction (left and right direction when used as an optical sheet for a display device placed in front of the passenger seat of a car) can be controlled.

[0052] FIG. 4 shows an angle θ 11 , θ 12 The angle θ 11 is the angle between an interface 4a, which is on the right side of the light absorbing portion 4 when the optical sheet 10 is placed with the base layer 1 side facing the observer, and the normal to the layer surface of the optical functional layer 2. 12 is the angle between the interface 4b on the left side of the light absorbing portion 4, among the interfaces between the light transmitting portion 3 and the light absorbing portion 4, and the normal to the layer surface of the optical function layer 2 in the same posture.

[0053] Angle θ 11 and angle θ 12 (i.e., the leg inclination angle in the trapezoidal cross section) is not particularly limited, but is, for example, 4.0° or more, and preferably 4.5° or more. 11 and θ 12 When the angle θ is in the above range, it becomes easy to control the viewing angle in the first direction (the left-right direction when used as an optical sheet for a display device placed in front of the passenger seat of a car). 11 and angle θ 12 is, for example, 6.5° or less, and preferably 5.5° or less. That is, the angle θ 11 and angle θ 12 is, for example, 4.0° or more and 6.5° or less, and preferably 4.5° or more and 5.5° or less.

[0054] In this embodiment, the light entrance side aperture ratio is, for example, 40% or less, and preferably 35% or less. When the light entrance side aperture ratio is in the above range, it becomes easy to control the viewing angle in the first direction (the left-right direction when used as an optical sheet for a display device arranged in front of the passenger seat of a car). On the other hand, the light entrance side aperture ratio is, for example, 25% or more, and preferably 30% or more. When the light entrance side aperture ratio is in the above range, it is possible to suppress a decrease in the luminance of the display device. That is, the light entrance side aperture ratio is, for example, 25% or more and 40% or less, and preferably 30% or more and 35% or less. The light entrance side aperture ratio is, as shown in FIG. 4, the ratio (Wa / Pa) of the width Wa of the light transmitting portion 3 present between the light absorbing portions 4 to the distance Pa between the centers of the adjacent light absorbing portions 4 on the surface opposite to the base layer 1 side.

[0055] The height Da of the light absorbing portion is not particularly limited, and is, for example, 110 μm or more, and preferably 120 μm or more. When the height Da of the light absorbing portion is in the above range, it becomes easy to control the viewing angle in the first direction (the left-right direction when used as an optical sheet for a display device placed in front of the passenger seat of a car). On the other hand, the height Da of the light absorbing portion is equal to or less than the thickness of the optical functional layer, and is, for example, 140 μm or less.

[0056] The OD value (optical density value) of the light absorbing portion is not particularly limited, but is, for example, 3.5 or more, and preferably 4.0 or more. On the other hand, the OD value of the light absorbing portion is, for example, 5.0 or less, and preferably 4.5 or less. Specifically, the OD value of the light absorbing portion is, for example, 3.5 or more, 5.0 or less, and preferably 4.0 or more, 4.5 or less.

[0057] The method for measuring the OD value of the light absorbing portion is as follows. First, the composition constituting the light absorbing portion is applied to a thickness of 60 μm on an easy-adhesion PET film, laminated with an untreated PET film, and one side of the film is UV-cured. Then, the other side is also UV-cured to prepare a measurement sample. The transmittance of this light absorbing layer is measured with a transmission densitometer, and the OD value is calculated.

[0058] 1 to 4 show an example in which the interface between the light transmitting portion 3 and the light absorbing portion 4 is a straight line in cross section, but the interface is not limited thereto and may be a broken line, a convex curved surface, a concave curved surface, etc. Furthermore, a plurality of light transmitting portions 3 and light absorbing portions 4 may have the same cross-sectional shape or different cross-sectional shapes having a predetermined regularity.

[0059] 2.Base material layer The substrate layer in this embodiment is a flat sheet-like member that supports the optical functional layer. A resin substrate is used as the substrate layer. Various materials can be used as the material of the substrate layer. For example, 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, processability, etc., and is inexpensively available can be used. Examples of such materials include polyesters such as polyethylene terephthalate (PET), triacetyl cellulose (TAC), acrylic resins, methacrylic resins, polycarbonates, and cycloolefin polymers.

[0060] As described later, when the optical sheet of this embodiment is used in a liquid crystal display device, it is preferable that the birefringence (retardation) of the base layer is small, taking into consideration the combination of a surface light source device and a lower polarizing plate. As materials with small birefringence, TAC, methacrylic resin, and polycarbonate are preferably used. Furthermore, for applications requiring high heat resistance such as in-vehicle applications, polycarbonate with a high glass transition point is more preferable. Specifically, the glass transition point of polycarbonate is 143°C, and it is generally suitable for in-vehicle applications requiring durability at 105°C.

[0061] On the other hand, from the viewpoint of suppressing rainbow unevenness, it is also preferable that the birefringence (retardation) of the base layer is large. As a material having a large birefringence, polyester is preferably used. Polyester is advantageous in terms of cost and mechanical strength.

[0062] From the viewpoint of suppressing rainbow unevenness, the retardation of the base layer is preferably 3000 nm or more. The upper limit of the retardation of the base layer is not particularly limited, but is preferably about 30000 nm. If the retardation of the base layer is too large, the base layer may become considerably thick. From the viewpoint of thinning the base layer, the retardation of the base layer is more preferably 5000 nm or more and 25000 nm or less, and further preferably 7000 nm or more and 20000 nm or less.

[0063] The retardation Re of the substrate layer is expressed by the following equation, where nx is the refractive index in the direction with the largest refractive index within the plane of the substrate layer (slow axis direction), ny is the refractive index in the direction perpendicular to the slow axis direction (fast axis direction), and d is the thickness of the substrate layer. Re = (nx-ny) × d

[0064] The retardation is measured using a phase difference measuring device. For example, a phase difference measuring device "KOBRA-WR" manufactured by Oji Scientific Instruments is used as the phase difference measuring device. The measurement angle is 0°, and the measurement wavelength is 589.3 nm.

[0065] The nx-ny (hereinafter referred to as Δn) is preferably 0.05 or more. If the Δn is too small, the thickness required to obtain the retardation may be large. On the other hand, the Δn is preferably 0.25 or less. If the Δn is too large, the substrate layer needs to be stretched excessively, so that the substrate layer is likely to tear or break, and the practicality as an industrial material may be significantly reduced. Therefore, the Δn is more preferably 0.07 or more and 0.15 or less. If the Δn exceeds 0.15, the durability of the substrate layer in the moist heat resistance test may be poor. Since the durability in the moist heat resistance test is excellent, the Δn is more preferably 0.12 or less.

[0066] The nx is preferably 1.66 or more and 1.78 or less, more preferably 1.68 or more and 1.73 or less. The ny is preferably 1.55 or more and 1.65 or less, more preferably 1.57 or more and 1.62 or less. When the nx and ny are within the above ranges and the relationship of Δn is satisfied, it is possible to achieve suitable antireflection performance and improvement of bright contrast.

[0067] The polyester is not particularly limited as long as it satisfies the above retardation, and examples thereof include linear saturated polyesters synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. Specific examples include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly(1,4-cyclohexylene dimethylene terephthalate), and polyethylene-2,6-naphthalate. The polyester may also be a copolymer of these polyesters. A mixture of polyester and other types of resins, with polyester as the main component, may also be used. In the above mixture, the content of polyester is, for example, 80 mol% or more. Among them, polyethylene terephthalate and polyethylene-2,6-naphthalate are preferred because of their good balance of mechanical properties, optical properties, and the like. In particular, polyethylene terephthalate (PET) is preferred. This is because PET is highly versatile and easily available. Furthermore, PET has excellent transparency, thermal or mechanical properties, and retardation can be controlled by stretching processing. It has a large intrinsic birefringence, and a large retardation can be obtained relatively easily even if it is thin.

[0068] When the substrate layer is a polyester substrate, the method of producing the polyester substrate is not particularly limited as long as it satisfies the above retardation. For example, a method of melting polyester, extruding the unstretched polyester into a sheet, and then stretching the unstretched polyester transversely using a tenter or the like at a temperature equal to or higher than the glass transition temperature, followed by heat treatment, can be mentioned. The transverse stretching temperature is preferably 80°C or higher and 130°C or lower, more preferably 90°C or higher and 120°C or lower. The transverse stretching ratio is preferably 2.5 times or higher and 6.0 times or lower, more preferably 3.0 times or higher and 5.5 times or lower. If the transverse stretching ratio is too large, the transparency of the resulting polyester substrate may be easily reduced. If the transverse stretching ratio is too small, the stretching tension is also reduced, so that the birefringence of the resulting polyester substrate may be reduced and the above retardation may not be satisfied. In addition, in the method of producing the polyester substrate, the unstretched polyester may be stretched transversely under the above conditions using a biaxial stretching tester, and then stretched in the flow direction relative to the transverse stretching (hereinafter also referred to as longitudinal stretching). In this case, the longitudinal stretching ratio is preferably 2 times or less. If the longitudinal stretching ratio is too large, the Δn may not satisfy the above-mentioned preferred range. The heat treatment temperature is preferably 100°C or more and 250°C or less, and more preferably 180°C or more and 245°C or less.

[0069] The method of controlling the retardation of the polyester substrate prepared by the above-mentioned method within the above range includes a method of appropriately setting the stretching ratio, stretching temperature, and thickness of the polyester substrate to be prepared. Specifically, the higher the stretching ratio, the easier it is to obtain a high retardation, and the lower the stretching ratio, the easier it is to obtain a low retardation. The lower the stretching temperature, the easier it is to obtain a high retardation, and the higher the stretching temperature, the easier it is to obtain a low retardation. The thicker the thickness, the easier it is to obtain a high retardation, and the thinner the thickness, the easier it is to obtain a low retardation.

[0070] The thickness of the polyester substrate is preferably 20 μm or more and 500 μm or less, more preferably 50 μm or more and 300 μm or less, and even more preferably 50 μm or more and 150 μm or less. If the thickness of the polyester substrate is too thin, the retardation of the polyester substrate may not satisfy the above range. If the thickness of the polyester substrate is too thin, the anisotropy of the mechanical properties becomes significant, and the substrate may be easily torn or broken, and the practicality as an industrial material may be significantly reduced. On the other hand, if the thickness of the polyester substrate is too thick, the polyester substrate may be very rigid, and the flexibility specific to the polymer film may be reduced, and the practicality as an industrial material may be reduced.

[0071] The total light transmittance of the substrate layer is preferably 80% or more, and more preferably 84% or more. The total light transmittance is measured in accordance with JIS K7361-1:1997.

[0072] 3. Other layers The optical sheet in this embodiment may have layers other than the substrate layer and the optical functional layer. Examples of the layers include a hard coat layer having a rough surface. The hard coat layer having such a rough surface is, for example, a hard coating layer having a rough surface with an arithmetic mean roughness Ra of 0.1 μm or more according to JIS B0601:1994. In this embodiment, the arithmetic mean roughness Ra of the hard coat layer is preferably 0.2 μm or more, more preferably 0.4 μm or less. The rough surface of the hard coat layer makes it difficult for the hard coat layer to be scratched by contact with other adjacent optical members when the optical sheet is incorporated into a display device. In addition, the rough surface of the hard coat layer suppresses optical contact, and thus suppresses the occurrence of interference fringes due to optical contact, making it difficult for the optical performance to deteriorate. The hard coat layer having a rough surface may be disposed on the surface of the substrate layer opposite the optical functional layer side (light output side), or may be disposed on the surface of the optical functional layer opposite the substrate layer side (light input side).

[0073] 4. Preparation method The optical sheet in this embodiment can be produced, for example, as follows. First, a light-transmitting portion is formed in the base layer. In this process, a base sheet that will become the base layer is inserted between a mold roll having a surface shape that allows the shape of the light-transmitting portion to be transferred, and a nip roll arranged to face the mold roll. At this time, the mold roll and the nip roll are rotated while a composition that constitutes the light-transmitting portion is supplied between the base sheet and the mold roll. As a result, the composition that constitutes the light-transmitting portion is filled into the grooves (the shape of which is the inverse of the shape of the light-transmitting portion) that correspond to the light-transmitting portion formed on the surface of the mold roll, and the composition conforms to the surface shape of the mold roll.

[0074] Examples of the composition constituting the light transmitting portion include ionizing radiation curable resins such as epoxy acrylates, urethane acrylates, polyether acrylates, polyester acrylates, and polythiols.

[0075] The composition that constitutes the light-transmitting portion is sandwiched between the mold roll and the base sheet and filled therein, and is irradiated with light for hardening from the base sheet side by a light irradiation device. This hardens the composition and fixes its shape. Then, the base layer and the molded light-transmitting portion are released from the mold roll by a release roll.

[0076] Next, the light absorbing portion is formed. To form the light absorbing portion, first, the gap between the light transmitting portions is filled with a composition that constitutes the light absorbing portion. Thereafter, the excess composition is scraped off with a doctor blade or the like. Then, the remaining composition is cured from the light transmitting portion side, thereby forming the light absorbing portion. Examples of the curing method include curing by ultraviolet irradiation and curing by heating.

[0077] The composition constituting the light absorbing portion is not particularly limited, and examples thereof include compositions in which colored light absorbing particles are dispersed in a photocurable resin such as urethane (meth)acrylate, polyester (meth)acrylate, epoxy (meth)acrylate, butadiene (meth)acrylate, etc. Also usable are compositions in which colored light absorbing particles are dispersed in a thermosetting resin.

[0078] Instead of dispersing light-absorbing particles, the entire light-absorbing portion can be colored with a pigment or dye. As the light-absorbing particles, light-absorbing colored particles such as carbon black are preferably used. As the light-absorbing particles, there are no particular limitations, and colored particles that selectively absorb a specific wavelength in accordance with the characteristics of the image light may be used. Specifically, examples include carbon black, graphite, metal salts such as black iron oxide, organic fine particles colored with dyes or pigments, and glass beads. In particular, colored organic fine particles are preferably used from the viewpoints of cost, quality, ease of availability, and the like. The average particle diameter of the colored particles is preferably 1.0 μm or more and 20 μm or less, more preferably 1.0 μm or more and 10 μm or less, and even more preferably 1.0 μm or more and 4.0 μm or less. Here, the "average particle diameter" refers to the diameter obtained by observing 100 light-absorbing particles with an electron microscope, measuring the diameters, and arithmetically averaging them.

[0079] 5.Optical Sheet The optical sheet in this embodiment has a rectangular shape having a pair of first sides L1 extending in a first direction and a pair of second sides L2 extending in a second direction in a plan view. The first side L1 may be longer than, shorter than, or the same as the second side L2. The first direction, the second direction, and the third direction are usually perpendicular to each other. In FIG. 1, the first side L1 is longer than the second side L2.

[0080] The use of the optical sheet in this embodiment is not particularly limited, and may be used in, for example, a display device. In particular, the optical sheet in this embodiment is preferably used in an in-vehicle display device, and more preferably used in a display device disposed in front of the passenger seat of the vehicle. The optical sheet may be disposed on the viewer's side of the display panel in the display device, or may be included in a surface light source device in the display device.

[0081] B-1. Surface light source device (first embodiment) The surface light source device in this embodiment includes the optical sheet of the above-mentioned first embodiment, and a light source that emits light incident on the optical sheet.

[0082] A surface light source device is usually used in a display device. Fig. 5 is an exploded perspective view illustrating a display device including the surface light source device of this embodiment. Fig. 6 shows a part of an exploded cross-sectional view of the display device cut along the line indicated by II-II in Fig. 5, and Fig. 7 shows a part of an exploded cross-sectional view of the display device cut along the line indicated by III-III in Fig. 5. The display devices shown in Figs. 5 to 7 are examples of liquid crystal display devices.

[0083] As shown in Figs. 5 to 7, a display device 50A including a surface light source device 20 in this embodiment includes a liquid crystal panel 15, the surface light source device 20, and a functional film 40. Figs. 5 to 7 also show the orientation of the display device in an installed position, but the installation position is not limited to this. For example, as shown in Fig. 5, the display device is preferably disposed in a position in which the first direction D1 in Figs. 1 to 4 is horizontal and the second direction D2 is vertical, but is not limited to this position. Each component will be described below.

[0084] The surface light source device 20 in Fig. 5 to Fig. 7 has the above-mentioned optical sheet 10A, is disposed on the opposite side of the liquid crystal panel 15 from the viewer side, and is an illumination device that emits planar light to the liquid crystal panel 15. The surface light source device 20 in Fig. 5 to Fig. 7 is configured as an edge-light type surface light source device, and has a light guide plate 21, a light source 25, a light diffusion plate 26, a prism layer 27, a reflective polarizing plate 28, an optical sheet 10A, and a reflecting sheet 29. As shown in Fig. 5 to Fig. 7, in the surface light source device 20, the optical sheet 10A is disposed such that the base layer 1 faces the viewer side with respect to the optical functional layer 2.

[0085] As shown in Fig. 5 to Fig. 7, the light guide plate 21 has a base 22 and rear surface optical elements 23. The light guide plate 21 is a plate-like member formed of a light-transmitting material as a whole. As shown in Fig. 5 to Fig. 7, one plate surface side of the light guide plate 21 facing the viewer is a smooth surface, and the other plate surface side opposite to this is a rear surface, on which a plurality of rear surface optical elements 23 are arranged.

[0086] Various materials can be used as materials for the base 22 and the rear optical element 23. For example, materials that are widely used as materials for optical sheets incorporated in display devices, have excellent mechanical properties, optical properties, stability, processability, etc., and are inexpensively available can be used. Examples of such materials include thermoplastic resins such as polymer resins having an alicyclic structure, methacrylic resins, polycarbonates, polystyrenes, acrylonitrile-styrene copolymers, methyl methacrylate-styrene copolymers, ABS resins, and polyethersulfones, as well as epoxy acrylate and urethane acrylate-based reactive resins (ionizing radiation curable resins, etc.).

[0087] The base 22 is a portion through which light is guided and which serves as a base for the rear surface optical element 23, and is in the form of a plate having a predetermined thickness.

[0088] The rear surface optical element 23 is a protruding element formed on the rear surface side of the base 22, and has a triangular prism shape in Fig. 5 to Fig. 7. The rear surface optical element 23 is shaped like a column with the ridgeline of the protruding apex extending horizontally, and a plurality of rear surface optical elements 23 are arranged at a predetermined pitch in a direction perpendicular to the extending direction (vertical direction). The rear surface optical element 23 in Fig. 5 to Fig. 7 has a triangular cross section, but is not limited thereto, and may have any cross section shape, such as a polygonal shape, a hemispherical shape, a part of a sphere, or a lens shape.

[0089] The arrangement direction of the multiple rear optical elements 23 is preferably the light guide direction. That is, they are arranged in a direction away from the light source 25, and the ridges of each rear optical element 23 extend parallel to the arrangement direction of the light source 25 or, in the case of a single long light source, the extension direction of the light source.

[0090] In this specification, the term "triangular shape" refers not only to a triangular shape in the strict sense, but also to an approximately triangular shape that includes limitations in manufacturing technology, errors during molding, etc. Similarly, terms used in this specification that specify other shapes or geometric conditions, such as "parallel," "orthogonal," "ellipse," and "circle," are also interpreted without being bound by their strict meanings, but with an error that allows the same optical function to be expected.

[0091] The light guide plate 21 having such a configuration can be manufactured by extrusion molding, or by molding the rear optical elements 23 on the base 22. In the light guide plate 21 manufactured by extrusion molding, the base 22 and the rear optical elements 23 can be integrally formed. In addition, when the light guide plate 21 is manufactured by molding, the rear optical elements 23 may be made of the same resin material as the base 22 or a different material.

[0092] The light source 25 is disposed on one of the side surfaces (end surfaces) of the base 22 of the light guide plate 21 in the direction in which the rear surface optical elements 23 are arranged. The light source is not particularly limited, and can be configured in various forms such as a fluorescent lamp such as a linear cold cathode fluorescent tube, a point-like LED (light emitting diode), or an incandescent light bulb. In Figs. 5 to 7, the light source 25 is made up of a plurality of LEDs, and is configured so that the turning on and off of each LED and / or the brightness of each LED when lit can be individually and independently adjusted by a control device (not shown).

[0093] 5 to 7 show an example in which the light source 25 is disposed on one side surface (end surface) as described above, but a light source may also be disposed on the side surface (end surface) opposite to this side surface (end surface). In this case, the shape of the rear surface optical element is also formed following a known example.

[0094] Next, the light diffusion plate 26 will be described. The light diffusion plate 26 is a member disposed on the light output side of the light guide plate 21 and has a function of diffusing and outputting the light incident thereon. This can further improve the uniformity of the light output from the light guide plate 21 and make scratches on the light guide plate 21 less noticeable. A known light diffusion plate can be used as a specific embodiment of the light diffusion plate, and for example, a form in which a light diffusing agent is dispersed in a base material can be mentioned. The light diffusion plate 26 can be used as a support plate for the prism layer 27 as shown in Figs. 5 to 7. In addition, when the light output surface of the light guide plate 21 is smooth, the light diffusion plate 26 may be bonded to the light guide plate 21 to be integrated.

[0095] As can be seen from Fig. 5 to Fig. 7, the prism layer 27 is provided closer to the liquid crystal panel 15 than the light diffusion plate 26, and is a layer including unit prisms 27a that are convex toward the liquid crystal panel 15. In Fig. 5 to Fig. 7, the unit prisms 27a have a predetermined cross section and extend in the light guide direction of the light guide plate 21 (the vertical direction in this embodiment). The multiple unit prisms 27a are arranged in a direction different from the light guide direction (the horizontal direction, which is perpendicular to the light guide direction in a plan view in this embodiment).

[0096] The cross-sectional shape of the unit prism of such a prism layer can be any known shape depending on the required function. Depending on the shape, the light can be further diffused or concentrated.

[0097] The extending direction and the arranging direction of the unit prisms are not limited to the above-mentioned configuration, and may be other configurations. For example, the unit prisms may have a predetermined cross section, extend in a direction perpendicular to the light guiding direction of the light guiding plate 21, and a plurality of unit prisms may be arranged in the light guiding direction.

[0098] The reflective polarizing plate 28 has a function of decomposing the incident light into two orthogonal polarized components (P wave and S wave), transmitting the polarized component in one direction (parallel to the transmission axis) (for example, P wave) and reflecting the polarized component in the other direction (parallel to the reflection axis) orthogonal to the one direction (for example, S wave). A known structure can be applied to such a reflective polarizing plate.

[0099] The reflective sheet 29 of the surface light source device 20 will be described. The reflective sheet 29 is a member for reflecting light emitted from the rear surface of the light guide plate 21 and causing the light to enter the light guide plate 21 again. As the reflective sheet 29, a sheet capable of so-called specular reflection, such as a sheet made of a material having high reflectance such as a metal, or a sheet including a thin film (e.g., a metal thin film) made of a material having high reflectance as a surface layer, can be preferably used.

[0100] C-1. Display device (first embodiment) The display device in this embodiment includes the optical sheet of the first embodiment described above and a display panel. The display device is a device that displays, for example, moving images, still images, text information, or an image composed of a combination of these on the display panel. According to the display device of this embodiment, it is possible to control the emission of image light in the vertical and horizontal directions. In particular, in the case of a display device disposed in front of the passenger seat of a car, it is possible to control the emission of image light to the driver's side, and also to control the reflection of the image light on the windshield in front of the passenger seat.

[0101] The display device of this embodiment has two further embodiments. The display device of this embodiment includes a surface light source device, and the surface light source device may include the above-mentioned optical sheet. In the display device of this embodiment, the above-mentioned optical sheet may be disposed on the viewer's side of the display panel.

[0102] C-1-1. Display device (first example of the first embodiment) The display device of this embodiment includes a surface light source device including the optical sheet of the first embodiment described above, and a display panel laminated on the surface light source device.

[0103] 5 to 7 are schematic plan views and cross-sectional views showing an example of a display device according to the present embodiment. Note that since Fig. 5 to Fig. 7 are described in the above section "B-1. Surface light source device (first embodiment)", description thereof will be omitted here.

[0104] 1. Surface light source device The surface light source device has been described above in the section "B-1. Surface Light Source Device (First Embodiment)," so a description thereof will be omitted here.

[0105] 2. Display panel The display panel is, for example, a liquid crystal panel. The liquid crystal panel 15 shown in Figs. 5 to 7 has an upper polarizing plate 13 arranged on the viewer side, a lower polarizing plate 14 arranged on the surface light source device 20 side, and a liquid crystal layer 12 arranged between the upper polarizing plate 13 and the lower polarizing plate 14. The upper polarizing plate 13 and the lower polarizing plate 14 have a function of decomposing the incident light into two orthogonal polarized components (P wave and S wave), transmitting the polarized component in one direction (parallel to the transmission axis) (for example, P wave) and absorbing the polarized component in the other direction (parallel to the absorption axis) orthogonal to the one direction (for example, S wave).

[0106] In the liquid crystal layer 12, a plurality of pixels are arranged vertically and horizontally in the direction along the layer surface, and an electric field can be applied to each region forming one pixel. Then, the orientation of the pixel to which the electric field is applied changes. As a result, the polarization direction of the polarized component (e.g., P wave) parallel to the transmission axis that has passed through the lower polarizing plate 14 arranged on the surface light source device 20 side (i.e., the light input side) rotates by 90° when passing through the pixel to which the electric field is applied, and on the other hand, maintains the polarization direction when passing through the pixel to which the electric field is not applied. Therefore, depending on whether or not an electric field is applied to the pixel, it is possible to control whether the polarized component (e.g., P wave) that has passed through the lower polarizing plate 14 is further transmitted through the upper polarizing plate 13 arranged on the light output side, or is absorbed and blocked by the upper polarizing plate 13.

[0107] In this manner, the liquid crystal panel 15 has a structure in which the transmission or blocking of light from the surface light source device 20 is controlled for each pixel to display an image.

[0108] There are several types of liquid crystal panels, but the type is not particularly limited, and any known type of liquid crystal panel can be used, such as TN, STN, VA, MVA, IPS, and OCB.

[0109] 3. Other materials The display device of this embodiment may have a functional film 40 arranged on the light output side of the liquid crystal panel 15, as shown in Figs. 5 to 7. The functional film 40 is a member having a function of improving the quality of image light and protecting the display device 50A. Examples of the functional film include an anti-reflection film, an anti-glare film, a hard coat film, a color tone correction film, and a light diffusion film, and the like, and the display device may be configured by using one of these alone or in combination.

[0110] 4. Effect Next, the operation of the display device 50A having the above-mentioned configuration will be described with reference to examples of optical paths. Note that the optical path examples are conceptual examples for the purpose of explanation and do not strictly represent the degree of reflection or refraction.

[0111] First, as shown in Fig. 7, light emitted from light source 25 enters light guide plate 21 from a light entrance surface, which is a side surface (end surface) of light guide plate 21. Fig. 7 shows, as an example, an example of the optical paths of light L21 and L22 entering light guide plate 21 from light source 25.

[0112] As shown in FIG. 7, light L21, L22 incident on the light guide plate 21 is repeatedly totally reflected on the light output side surface of the light guide plate 21 and the rear surface on the opposite side thereof due to the difference in refractive index with air, and travels in the light guide direction (downward in the plane of the paper in FIG. 7).

[0113] However, a rear optical element 23 is disposed on the rear surface of the light guide plate 21. For this reason, as shown in Fig. 7, the direction of light L21, L22 traveling inside the light guide plate 21 may be changed by the rear optical element 23, and the light may be incident on the light output surface and the rear surface at an incident angle less than the critical angle of total reflection. In this case, the light may be emitted from the light output surface of the light guide plate 21 and the rear surface opposite thereto.

[0114] The light L21 and L22 emitted from the light output surface proceeds toward the light diffusion plate 26 arranged on the light output side of the light guide plate 21. On the other hand, the light emitted from the back surface is reflected by the reflection sheet 29 arranged on the back surface of the light guide plate 21, and enters the light guide plate 21 again to travel within the light guide plate 21.

[0115] The light traveling within the light guide plate 21 and the light that is redirected by the rear optical element 23 and reaches the light output surface at an incident angle less than the total reflection critical angle are generated in each area along the light guide direction within the light guide plate 21. Therefore, the light traveling within the light guide plate 21 is gradually emitted from the light output surface. This makes it possible to uniformize the light amount distribution along the light guide direction of the light that is emitted from the light output surface of the light guide plate 21.

[0116] The light emitted from the light guide plate 21 then reaches the light diffusion plate 26, where the uniformity is improved. The light is then diffused or concentrated as necessary by the prism layer 27, and the light that has exited the prism layer 27 reaches the reflective polarizing plate 28. Here, the light polarized in the direction along the transmission axis of the reflective polarizing plate 28 passes through the reflective polarizing plate 28 and travels toward the optical sheet 10A.

[0117] On the other hand, the light polarized along the reflection axis of the reflective polarizer 28 is reflected as shown by the dotted arrow in FIG. 7 and returned to the light guide plate 21. The returned light is reflected by the light guide plate 21, the rear optical element 23, or the reflection sheet 29, and travels again toward the reflective polarizer 28. The polarization direction of some of the light changes during this reflection, and some of the light passes through the reflective polarizer 28. The other light is returned again to the light guide plate. The light reflected by the reflective polarizer 28 in this way can also pass through the reflective polarizer 28 by repeating reflections. This increases the utilization rate of the light from the light source 25. Here, the polarization direction of the light emitted from the reflective polarizer 28 is aligned with the transmission axis of the lower polarizer 14, and the light passes through the lower polarizer 14 as polarized light.

[0118] The light that has exited reflective polarizing plate 28 reaches optical sheet 10 A. The light that has entered optical sheet 10 A travels along the optical path described above.

[0119] The light emitted from the optical sheet 10A is incident on the lower polarizing plate 14 of the liquid crystal panel 15. The lower polarizing plate 14 transmits one polarized component of the incident light and absorbs the other polarized component. The light transmitted through the lower polarizing plate 14 is selectively transmitted through the upper polarizing plate 13 depending on the state of the electric field applied to each pixel. In this way, the liquid crystal panel 15 selectively transmits the light from the surface light source device 20 for each pixel, allowing the viewer of the liquid crystal display device to view an image. At that time, the image light is provided to the viewer via the functional film 40, improving the quality of the image.

[0120] 5.Applications The display device of this embodiment is preferably used in applications that require control of emission of image light in the vertical and horizontal directions.

[0121] The display device in this embodiment is preferably used as an in-vehicle display device, for example, and is particularly preferably used as a passenger seat display device disposed in front of the passenger seat of a vehicle.

[0122] As shown in Figs. 5 to 7, in the display device 50A of this embodiment, the base layer 1 of the optical sheet 10A is disposed on the viewer side with respect to the optical functional layer 2. Fig. 8(a) is a schematic diagram of the front of the vehicle interior in which the display device 50A of this embodiment is disposed in front of the passenger seat of the vehicle. Fig. 8(b) is a plan view for explaining the state of the optical sheet of the display device in Fig. 8(a). In Figs. 8(a) and 8(b), the optical sheet is disposed so that the first direction D1 in the optical sheet is horizontal (left-right direction of the vehicle), the second direction D2 is vertical, and the third direction D3 is horizontal (front-rear direction of the vehicle). However, the installation posture of the display device is not limited to this.

[0123] When the display device of this embodiment is used as a passenger seat display device disposed in front of the passenger seat of a vehicle, it is possible to control the emission of image light to the driver's side. Also, it is possible to control the reflection of the image light on the windshield in front of the passenger seat, thereby preventing the driver from seeing the reflection on the windshield.

[0124] Moreover, the display device in this embodiment can be used as a rear seat display device arranged on the ceiling or headrest of a vehicle. When a rear seat display device is installed in each rear seat, the emission of image light in the left and right directions can be suppressed, and the deterioration of visibility due to the image light of the adjacent rear seat display device being reflected on the observer's rear seat display device can be suppressed. In particular, when an observer is observing an image with low luminance on the rear seat display device, and an image with high luminance is displayed on the adjacent rear seat display device, the deterioration of visibility can be further suppressed. Furthermore, the emission of image light in the upward direction can be suppressed, and the reflection of the image light on the ceiling of the rear seat, especially at night, can be controlled, and the driver can be prevented from viewing the reflection on the ceiling.

[0125] The display device according to the present embodiment can be used as a display device arranged in passenger seats of a bus, a train, an airplane, etc. In this case, the emission of image light in the left and right directions can be suppressed, and privacy can be protected. Also, the emission of image light in the upward direction can be suppressed, and the reflection of the image light on the ceiling of the passenger seats, especially at night, can be controlled, and the reflection on the ceiling can be prevented from being seen by people other than the observer.

[0126] The display device of this embodiment can be used for various purposes, such as advertisements, presentations, television images, and display of various information, both indoors and outdoors.

[0127] C-1-2. Display device (second example of the first embodiment) The display device of this embodiment includes a display panel, and the optical sheet of the above-described first embodiment, which is disposed on the viewer's side of the display panel.

[0128] FIG. 9 is an exploded cross-sectional view illustrating a display device in this embodiment. As shown in FIG. 9, a display device 50E in this embodiment includes a display panel 30 and an optical sheet 10A arranged on the viewer side of the display panel 30. As shown in FIG. 9, in the display device 50E, the optical sheet 10A is arranged so that the base layer 1 faces the viewer side with respect to the optical functional layer 2. FIG. 9 also shows the orientation of the display device in an installed position, but the installation position is not limited to this. For example, as shown in FIG. 9, the display device is preferably arranged in an orientation in which the first direction D1 in FIGS. 1 to 4 is horizontal and the second direction D2 is vertical, but is not limited to this orientation.

[0129] 1. Optical sheets The optical sheet has been described above in the section "A-1. Optical Sheet (First Embodiment)," so a description thereof will be omitted here.

[0130] 2. Display panel Examples of the display panel include a liquid crystal panel and an organic electroluminescence panel. The liquid crystal panel is the same as the liquid crystal panel described in the above section "C-1-1. Display device (first example of the first embodiment)". The organic electroluminescence panel may be a known organic electroluminescence panel.

[0131] 3. Other materials The display device of this embodiment may have a functional film 40 disposed on the light output side of the optical sheet 10A, as shown in Fig. 9. The functional film is the same as the functional film described in the above section "C-1-1. Display device (first example of first embodiment)".

[0132] When the display panel is a liquid crystal panel, the display device of the present embodiment usually has a surface light source device on the surface of the liquid crystal panel opposite to the optical sheet side. The surface light source device may be a known surface light source device.

[0133] On the other hand, when the display panel is an organic electroluminescence panel, the organic electroluminescence panel is of a self-luminous type.

[0134] 4.Applications The use of the display device in this embodiment is similar to that described in the above section "C-1-1. Display device (first example of first embodiment)," and therefore a description thereof will be omitted here.

[0135] A-2. Optical sheet (second embodiment) The optical sheet 10B of this embodiment includes a base layer 1 and an optical functional layer 2 laminated on one surface of the base layer 1, as shown in, for example, FIG. 1 to FIG. 4. The optical sheet 10B of this embodiment has a rectangular shape having a pair of first sides L1 extending in a first direction and a pair of second sides L2 extending in a second direction in a plan view. The optical functional layer 2 has a plurality of light transmitting portions 3 having a predetermined cross section and extending in one direction, and a light absorbing portion 4 formed between adjacent light transmitting portions 3, and the predetermined cross section of the light transmitting portion 3 is a trapezoid, and the short upper base is the light incident side. The optical sheet 10B is an optical sheet for a display device disposed in front of a passenger seat of a vehicle, and the extension direction of the light transmitting portion 3 has an angle of 1.5° or more and 20° or less with respect to the second direction D2.

[0136] The details of FIGS. 1 to 4 are described above in the section "A-1. Optical sheet (first embodiment)," so description thereof will be omitted here.

[0137] The optical sheet in this embodiment includes an optical functional layer having light transmitting portions and light absorbing portions extending in a predetermined direction and having predetermined cross sections, and thereby can reduce the light transmittance in a direction tilted at ±30° toward the first direction with respect to the third direction. Specifically, when the light transmittance in the third direction is taken as 100%, the relative transmittance, which is the ratio of the light transmittance in a direction tilted at ±30° toward the first direction with respect to the third direction, can be made 1% or less.

[0138] Furthermore, when the light output angle in the first direction D1 is controlled, the extension direction of the light transmitting section 3 has an angle θ with respect to the second direction that is greater than or equal to 1.5° and less than or equal to 20°, making it possible to control the light output angle in the second direction D2.

[0139] Therefore, when the optical sheet of the present embodiment is used in a display device, it is possible to control the light emission angle in the left-right direction and the up-down direction of the display device. More specifically, when the optical sheet is used as an optical sheet for a display device disposed in front of the passenger seat of a car, it is possible to control the emission of image light to the driver's side, and also possible to control the reflection of the image light on the windshield in front of the passenger seat.

[0140] The optical sheet in this embodiment is an optical sheet for a display device disposed in front of the passenger seat of a vehicle.

[0141] Other features of the optical sheet in this embodiment are similar to those in "A-1. Optical sheet (first embodiment)" described above, and therefore will not be described here.

[0142] B-2. Surface light source device (second embodiment) 5 to 7, the surface light source device 20 of the present embodiment includes the optical sheet 10B of the second embodiment described above and a light source 25 that emits light incident on the optical sheet 10B. The surface light source device of the present embodiment is used in a display device for a passenger seat.

[0143] The details of FIGS. 5 to 7 are described above in the section "B-1. Surface light source device (first embodiment)," so description thereof will be omitted here.

[0144] The light source and other members of the surface light source device are described above in the section "B-1. Surface light source device (first embodiment)," so description thereof will be omitted here.

[0145] C-2. Display device (second embodiment) The display device of this embodiment includes the optical sheet of the second embodiment and a display panel. When the display device of this embodiment is used as a display device disposed in front of the passenger seat of a car, it is possible to control emission of image light to the driver's side and to control reflection of the image light on the windshield in front of the passenger seat.

[0146] The display device of this embodiment has two further embodiments. The display device of this embodiment includes a surface light source device, and the surface light source device may include the above-mentioned optical sheet. In the display device of this embodiment, the above-mentioned optical sheet may be disposed on the viewer's side of the display panel.

[0147] C-2-1. Display device (first example of second embodiment) The display device in this embodiment includes a surface light source device including the above-mentioned optical sheet, and a display panel laminated on the surface light source device.

[0148] 5 to 7 are schematic plan views and cross-sectional views showing an example of a display device of this embodiment. As FIG. 5 to FIG. 7 have been described in the above section "B-1. Surface light source device (first embodiment)", description thereof will be omitted here. As shown in FIG. 5 to FIG. 7, the display device 50B of this embodiment is disposed such that the base layer 1 of the optical sheet 10B is on the observer (passenger seat) side with respect to the optical functional layer 2.

[0149] 1. Surface light source device The surface light source device has been described above in the section "B-2. Surface light source device (second embodiment)," so description thereof will be omitted here.

[0150] 2. Display panels and other components The display panel and other members have been described above in the section "C-1-1. Display device (first example of first embodiment)," and therefore description thereof will be omitted here.

[0151] 3.Applications The display device in this embodiment is used as a display device disposed in front of the passenger seat of a vehicle. FIG. 8(a) is a schematic diagram of the front of a vehicle interior in which a display device 50B in this embodiment is disposed in front of the passenger seat of a vehicle. FIG. 8(b) is a plan view for explaining the state of the optical sheet of the display device 50B in FIG. 8(a). In FIG. 8(a) and FIG. 8(b), the optical sheet is disposed so that the first direction D1 in the optical sheet is horizontal (left-right direction of the vehicle), the second direction D2 is vertical, and the third direction D3 is horizontal (front-rear direction of the vehicle). However, the installation posture of the display device is not limited to this.

[0152] C-2-2. Display device (second example of the second embodiment) The display device in this embodiment includes a display panel, and the optical sheet of the above-mentioned second embodiment, which is disposed on the viewer's side of the display panel.

[0153] Fig. 9 is an exploded cross-sectional view illustrating a display device 50F in this embodiment. Fig. 9 was described in the above section "C-1-2. Display device (second example of first embodiment)", so the description here is omitted. As shown in Fig. 9, the display device 50F in this embodiment is disposed such that the base layer 1 of the optical sheet 10B is on the observer (passenger seat) side with respect to the optical function layer 2.

[0154] 1. Optical sheets The optical sheet has been described above in the section "A-2. Optical sheet (second embodiment)," so description thereof will be omitted here.

[0155] 2. Display panels and other components The display panel and other members are described above in the section "C-1-2. Display device (second example of first embodiment)," so description thereof will be omitted here.

[0156] 4.Applications The display device in this embodiment is used as a display device disposed in front of the passenger seat of a car. The use of the display device in this embodiment is similar to that described in the above section "C-1-2. Display device (second example of the first embodiment)", so the description here is omitted.

[0157] C-3. Display device (third embodiment) The display device of this embodiment is a display device comprising an optical sheet and a display panel, the optical sheet comprising a base layer and an optical functional layer laminated on one side of the base layer, the optical functional layer having a plurality of light-transmitting portions having a predetermined cross-section and extending in one direction, and light-absorbing portions formed between adjacent light-transmitting portions, the predetermined cross-section of the light-transmitting portions being trapezoidal with a shorter upper base being the light-entering side, the optical sheet having a relative transmittance of 1% or less when the light transmittance in the normal direction of the main surface of the optical sheet is taken as 100%, which is the ratio of the light transmittance in a direction inclined ±30° left and right from the normal direction when the display device is installed, and the extension direction of the light-transmitting portions as viewed from the normal direction has an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0158] The display device of this embodiment has two further embodiments. The display device of this embodiment includes a surface light source device, and the surface light source device may include the above-mentioned optical sheet. In the display device of this embodiment, the above-mentioned optical sheet may be disposed on the viewer's side of the display panel.

[0159] C-3-1. Display device (first example of the third embodiment) 5 to 7 are schematic plan views and cross-sectional views showing an example of the display device of this embodiment. Also, FIGS. 1 to 4 are schematic perspective views, cross-sectional views and plan views showing an example of the optical sheet in the display device of this embodiment. As shown in FIGS. 5 to 7, the display device 50C of this embodiment includes a surface light source device 20 including an optical sheet 10C, and a liquid crystal panel 15 laminated on the surface light source device 20. As shown in FIGS. 1 to 4, the optical sheet 10C of this embodiment includes a base layer 1 and an optical functional layer 2 laminated on one surface of the base layer 1, and the optical functional layer 2 has a plurality of light-transmitting portions 3 having a predetermined cross section and extending in one direction, and a light-absorbing portion 4 formed between adjacent light-transmitting portions 3, and the predetermined cross section of the light-transmitting portion 3 is a trapezoid, and the short upper base is the light-entering side. 2, when the display device 50C is installed, the optical sheet 10C has a relative transmittance of 1% or less, which is the ratio of the light transmittance in a direction inclined by ±30° to the left and right from the normal direction N, when the light transmittance in the normal direction N (the third direction D3 in FIGS. 1 to 4) of the main surface S of the optical sheet is taken as 100%. Also, as shown in FIG 3, when the display device 50C is installed, the extension direction of the light transmitting portion 3 of the optical sheet 10C as viewed from the normal direction N has an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0160] 1 to 4 are described in detail in the above section "A-1. Optical sheet (first embodiment)", and therefore will not be described here. Also, as for Figs. 5 to 7, they are described in the above section "B-1. Surface light source device (first embodiment)", and therefore will not be described here.

[0161] The display device 50C of this embodiment has a predetermined optical sheet 10C. In the optical sheet 10C of this embodiment, when the display device is installed, the relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±30° in the left-right direction with respect to the normal direction, is equal to or less than a predetermined value, so that it is possible to control the light output angle in the left-right direction of the display device. Furthermore, in a state in which the light output angle in the left-right direction is controlled, the extension direction of the light transmitting portion as viewed from the normal direction has an angle θ in a predetermined range with respect to the vertical direction, so that it is possible to control the light output angle in the up-down direction of the display device.

[0162] Therefore, the display device can control the light emission angle in the left-right and up-down directions. More specifically, when the display device is placed in front of the passenger seat of a car, it is possible to control the emission of image light to the driver's side and also to control the reflection of the image light on the windshield in front of the passenger seat.

[0163] 1. Surface light source device The surface light source device includes a predetermined optical sheet. As shown in Figs. 1 to 4, when a display device is installed, the optical sheet 10C in this embodiment has a relative transmittance of 1% or less, which is the ratio of the light transmittance in a direction inclined by ±30° to the left and right from the normal direction N, when the light transmittance in the normal direction N (the third direction D3 in Figs. 1 to 4) of the main surface of the optical sheet is taken as 100%. The relative light transmittance is preferably 0.6% or less, and more preferably 0.4% or less.

[0164] In the optical sheet of this embodiment, when the light transmittance in the normal direction is taken as 100%, the relative transmittance, which is the ratio of the light transmittance in directions inclined ±20° to the left or right from the normal direction, is preferably 10% or less, and more preferably 5% or less.

[0165] Furthermore, in the optical sheet of this embodiment, when the display device is installed, the extension direction of the light transmitting portion as viewed from the normal direction has an angle of 1.5° or more and 20° or less with respect to the vertical direction. The angle θ is 1.5° or more, and may be 5° or more, or 10° or more. Meanwhile, the angle θ may be 20° or less and 15° or less. When the angle θ is within the above range, it is possible to control the light output angle in the left-right direction. In addition, in FIG. 1 and FIG. 3, the light transmitting portion 3 has an angle θ on the right side (+D1 side) with respect to the vertical direction. In this case, it is preferable that the left side (-D1 side) is the driver's seat side. Meanwhile, the light transmitting portion 3 may have an angle θ on the left side (-D1 side) with respect to the second direction D2. In this case, it is preferable that the right side (+D1 side) is the driver's seat side.

[0166] The angle θ is obtained by the following method. First, the display device 50 is set in a state as illustrated in FIG. 8(a) and FIG. 8(b). In this case, it does not matter whether the optical sheet of the display device 50 is vertically or horizontally long. Next, when viewed from the normal direction of the main surface of the optical sheet (the third direction D3 in FIG. 8(b)), that is, when an observer (e.g., a passenger seat) views the display device 50 from the front, the smaller angle between the vertical line (a line in the direction of gravity) and the boundary line BL between the light transmitting portion 3 and the light absorbing portion 4 is measured. When measuring the angle, the boundary line BL between the light transmitting portion 3 and the light absorbing portion 4 on the surface of the short upper base of the light transmitting portion 3 and the long lower base of the light absorbing portion 4 of the optical function layer 2 is used. In addition, as illustrated in FIG. 8(b), the angle is measured at two points on each of the left and right sides of the display device 50, and the arithmetic average value of the four measured values ​​is taken as the angle θ. The above two locations are 1 / 3 of the vertical length K of the display device 50 from the top of the display device 50, and 1 / 3 of the vertical length K of the display device 50 from the bottom of the display device 50.

[0167] The characteristics of the optical sheet having the above optical properties and other characteristics in this embodiment are similar to those of the above-mentioned "A-1. Optical sheet (first embodiment)", so the description here will be omitted. The other members of the surface light source device are described in the above "B-1. Surface light source device (first embodiment)", so the description here will be omitted.

[0168] 2. Display panels and other components The display panel and other members have been described above in the section "C-1-1. Display device (first example of first embodiment)," and therefore description thereof will be omitted here.

[0169] 3.Applications The use of the display device in this embodiment is similar to that of "C-1-1. Display device (first example of first embodiment)" described above, and therefore a description thereof will be omitted here.

[0170] C-3-2. Display device (second example of the third embodiment) FIG. 9 is a schematic plan view and a cross-sectional view showing an example of the display device of this embodiment. Also, FIGS. 1 to 4 are schematic perspective views, cross-sectional views, and plan views showing an example of an optical sheet in the display device of this embodiment. As shown in FIG. 9, the display device 50G of this embodiment includes a display panel 30 and an optical sheet 10C arranged on the viewer side of the display panel 30. As shown in FIGS. 1 to 4, the optical sheet 10C of this embodiment includes a base layer 1 and an optical functional layer 2 laminated on one surface of the base layer 1, and the optical functional layer 2 has a plurality of light-transmitting portions 3 having a predetermined cross section and extending in one direction, and a light-absorbing portion 4 formed between adjacent light-transmitting portions 3, and the predetermined cross section of the light-transmitting portion 3 is a trapezoid, and the short upper base is the light-entering side. 2, when the display device 50G is installed, the optical sheet 10C has a relative transmittance of 1% or less, which is the ratio of the light transmittance in a direction inclined by ±30° to the left and right from the normal direction N, when the light transmittance in the normal direction N (the third direction D3 in FIGS. 1 to 4) of the main surface S of the optical sheet is taken as 100%. Also, as shown in FIG 3, when the display device 50G is installed, the extension direction of the light transmitting portions 3 of the optical sheet 10C as viewed from the normal direction N has an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0171] 1 to 4 are described in detail in the above section "A-1. Optical sheet (first embodiment)", and therefore will not be described here. Also, FIG. 9 is described in the above section "C-1-2. Display device (second example of first embodiment)", and therefore will not be described here.

[0172] 1. Optical sheets The optical sheet is similar to the optical sheet described in the above section "C-3-1. Display device (first example of third embodiment)," and therefore a description thereof will be omitted here.

[0173] 2. Display panels and other components The display panel and other members are described above in the section "C-1-2. Display device (second example of first embodiment)," so description thereof will be omitted here.

[0174] 3.Applications The use of the display device in this embodiment is similar to that of "C-1-1. Display device (first example of first embodiment)" described above, and therefore a description thereof will be omitted here.

[0175] C-4. Display device (fourth embodiment) The display device of this embodiment comprises an optical sheet and a display panel, and is disposed in front of the passenger seat of a vehicle, the optical sheet comprising a base layer and an optical functional layer laminated on one side of the base layer, the optical functional layer having a plurality of light-transmitting portions having a predetermined cross-section and extending in one direction, and light-absorbing portions formed between adjacent light-transmitting portions, the predetermined cross-section of the light-transmitting portions being trapezoidal with a shorter upper base being the light-entering side, and the optical sheet being such that, when the display device is disposed in front of the passenger seat of a vehicle, the extension direction of the light-transmitting portions as viewed from the normal direction of the main surface of the optical sheet has an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0176] The display device of this embodiment has two further embodiments. The display device of this embodiment includes a surface light source device, and the surface light source device may include the above-mentioned optical sheet. In the display device of this embodiment, the above-mentioned optical sheet may be disposed on the viewer's side of the display panel.

[0177] C-4-1. Display device (first example of the fourth embodiment) 5 to 7 are schematic plan views and cross-sectional views showing an example of the display device of this embodiment. Also, FIGS. 1 to 4 are schematic perspective views, cross-sectional views and plan views showing an example of the optical sheet in the display device of this embodiment. As shown in FIGS. 5 to 7, the display device 50D in this embodiment is a display device that includes a surface light source device 20 including an optical sheet 10D and a liquid crystal panel 15 laminated on the surface light source device 20, and is disposed in front of the passenger seat of a car. As shown in FIGS. 1 to 4, the optical sheet 10D in this embodiment includes a base layer 1 and an optical functional layer 2 laminated on one surface of the base layer 1, and the optical functional layer 2 has a plurality of light-transmitting portions 3 having a predetermined cross section and extending in one direction, and a light-absorbing portion 4 formed between adjacent light-transmitting portions 3, and the predetermined cross section of the light-transmitting portion 3 is a trapezoid, and the short upper base is the light-entering side. When the display device is installed in front of the passenger seat of a car, the extension direction of the light-transmitting portion 3 of the optical sheet 10D as viewed from the normal direction N (the third direction D3 in Figures 1 to 4) of the main surface of the optical sheet 10D forms an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0178] The display device 50D in this embodiment has a predetermined optical sheet 10D. The optical sheet 10D in this embodiment includes an optical functional layer having a light transmitting portion and a light absorbing portion extending in a predetermined direction and having a predetermined cross section, so that when the display device is installed in front of the passenger seat of a car, the light transmittance in a direction inclined by ±30° to the left and right with respect to the normal direction can be reduced. Specifically, when the light transmittance in the normal direction is 100%, the relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±30° to the left and right with respect to the normal direction, can be 1% or less. Therefore, it is possible to control the light output angle in the left and right direction of the display device.

[0179] Furthermore, in a state where the light emission angle in the left-right direction is controlled, the extension direction of the light transmitting portion as viewed from the normal direction has an angle θ in a predetermined range with respect to the vertical direction, so that the light emission angle in the up-down direction of the display device can be controlled. Therefore, the display device of this embodiment can control the emission of image light to the driver's side, and can also control the reflection of the image light on the windshield in front of the passenger seat.

[0180] 1. Surface light source device The surface light source device includes a predetermined optical sheet. The optical sheet 10D in this embodiment includes an optical functional layer that extends in a predetermined direction and has a light-transmitting portion and a light-absorbing portion having a predetermined cross section. As a result, when a display device 50D having the predetermined optical sheet 10D is installed in front of the passenger seat of a car, when the light transmittance in the normal direction N (the third direction D3 in Figs. 1 to 4) of the main surface of the optical sheet 10D is set to 100%, the relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±30° to the left and right from the normal direction N, can be set to 1% or less. The relative light transmittance is preferably 0.6% or less, more preferably 0.4% or less.

[0181] In the optical sheet of this embodiment, when the light transmittance in the normal direction is taken as 100%, the relative transmittance, which is the ratio of the light transmittance in directions inclined ±20° to the left or right from the normal direction, is preferably 10% or less, and more preferably 5% or less.

[0182] Furthermore, in the optical sheet of this embodiment, when the display device is installed in front of the passenger seat of the car, the extension direction of the light transmitting portion as viewed from the normal direction has an angle of 1.5° or more and 20° or less with respect to the vertical direction. The angle θ is 1.5° or more, and may be 5° or more, or 10° or more. On the other hand, the angle θ may be 20° or less and 15° or less. When the angle θ is in the above range, it is possible to control the light output angle in the left-right direction. In addition, in FIG. 1 and FIG. 3, the light transmitting portion 3 has an angle θ on the right side (+D1 side) with respect to the vertical direction. In this case, it is preferable that the left side (-D1 side) is the driver's seat side. On the other hand, the light transmitting portion 3 may have an angle θ on the left side (-D1 side) with respect to the vertical direction. In this case, it is preferable that the right side (+D1 side) is the driver's seat side.

[0183] Other features of the optical sheet in this embodiment are the same as those in "A-1. Optical sheet (first embodiment)" above, so the description here will be omitted. Other members of the surface light source device are described in "B-1. Surface light source device (first embodiment)" above, so the description here will be omitted.

[0184] 2. Display panels and other components The display panel and other members have been described above in the section "C-1-1. Display device (first example of first embodiment)," and therefore description thereof will be omitted here.

[0185] 3.Applications The display device in this embodiment is placed in front of the passenger seat of the vehicle. Fig. 8(a) is a schematic diagram of the front of the vehicle interior when the display device 50D in this embodiment is placed in front of the passenger seat of the vehicle. Fig. 8(b) is a plan view for explaining the state of the optical sheet of the display device in Fig. 8(a). In Figs. 8(a) and 8(b), the optical sheet is placed so that the left-right direction is horizontal (left-right direction of the vehicle), the up-down direction is vertical, and the thickness direction is horizontal (front-rear direction of the vehicle). However, the installation posture of the display device is not limited to this.

[0186] C-4-2. Display device (second example of the fourth embodiment) FIG. 9 is a schematic plan view and a cross-sectional view showing an example of the display device of this embodiment. Also, FIGS. 1 to 4 are schematic perspective views, cross-sectional views, and plan views showing an example of the optical sheet in the display device of this embodiment. As shown in FIG. 9, the display device 50H in this embodiment is a display device that includes a display panel 30 and an optical sheet 10D arranged on the observer side of the display panel 30, and is arranged in front of the passenger seat of a car. As shown in FIGS. 1 to 4, the optical sheet 10D in this embodiment includes a base layer 1 and an optical functional layer 2 laminated on one surface of the base layer 1, and the optical functional layer 2 has a plurality of light-transmitting portions 3 having a predetermined cross section and extending in one direction, and a light-absorbing portion 4 formed between adjacent light-transmitting portions 3, and the predetermined cross section of the light-transmitting portion 3 is a trapezoid, and the short upper base is the light-entering side. When the display device is installed in front of the passenger seat of a car, the extension direction of the light-transmitting portion 3 of the optical sheet 10D as viewed from the normal direction N (the third direction D3 in Figures 1 to 4) of the main surface of the optical sheet 10D forms an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0187] The display device 50D in this embodiment has a predetermined optical sheet 10D. The optical sheet 10D in this embodiment includes an optical functional layer having a light transmitting portion and a light absorbing portion extending in a predetermined direction and having a predetermined cross section, so that when the display device is installed in front of the passenger seat of a car, the light transmittance in a direction inclined by ±30° to the left and right with respect to the normal direction can be reduced. Specifically, when the light transmittance in the normal direction is 100%, the relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±30° to the left and right with respect to the normal direction, can be 1% or less. Therefore, it is possible to control the light output angle in the left and right direction of the display device.

[0188] Furthermore, in a state where the light emission angle in the left-right direction is controlled, the extension direction of the light transmitting portion as viewed from the normal direction has an angle θ in a predetermined range with respect to the vertical direction, so that the light emission angle in the up-down direction of the display device can be controlled. Therefore, the display device of this embodiment can control the emission of image light to the driver's side, and can also control the reflection of the image light on the windshield in front of the passenger seat.

[0189] 1. Optical sheets The optical sheet is the same as the optical sheet described in the above section "C-4-2. Display device (second example of the fourth embodiment)."

[0190] 2. Display panels and other components The display panel and other members have been described above in the section "C-1-1. Display device (first example of first embodiment)," and therefore description thereof will be omitted here.

[0191] 3.Applications The uses of the display device in this embodiment are similar to those of "C-1-1. Display device (first example of first embodiment)" above.

[0192] A-3. Optical sheet (fifth embodiment) FIG. 1 is a schematic perspective view showing an example of the optical sheet of this embodiment. FIG. 10 shows a cross-sectional view of the optical sheet cut along the line II in FIG. 1. FIG. 3 is a plan view of the optical sheet shown in FIG. 1, seen along the direction (-D3 direction) from the base layer 1 to the optical functional layer 2. FIG. 4 is an enlarged cross-sectional view of the optical sheet shown in FIG. 10. As shown in FIGS. 1, 3, 4, and 10, the optical sheet 10E of this embodiment includes a base layer 1 and an optical functional layer 2 laminated on one surface of the base layer 1. The optical sheet 10E of this embodiment has a rectangular shape having a pair of first sides L1 extending in a first direction D1 and a pair of second sides L2 extending in a second direction D2 in a plan view. The optical functional layer 2 has a plurality of light transmitting parts 3 extending in one direction with a predetermined cross section, and a light absorbing part 4 formed between adjacent light transmitting parts 3. As shown in Fig. 10, the cross section of the light transmitting portion 3 is a trapezoid, and the shorter upper base is the light entering side (light source side). In this embodiment, as shown in Fig. 10, when the light transmittance in the third direction D3 is 100%, the relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±20° toward the first direction D1 with respect to the third direction D3, is 10% or less. Furthermore, as shown in Fig. 3, the extension direction of the light transmitting portion 3 has an angle θ of 1.5° or more and 20° or less with respect to the second direction D2.

[0193] According to the optical sheet 10A of the present embodiment, when the light transmittance in the third direction D3 is 100%, the relative transmittance, which is the ratio of the light transmittance in the direction inclined by ±20° toward the first direction side with respect to the third direction D3, is equal to or less than a predetermined value, so that it is possible to control the light output angle in the first direction D1. Furthermore, in a state in which the light output angle in the first direction D1 is controlled, the extension direction of the light transmitting portion 3 has an angle θ of 1.5° or more and 20° or less with respect to the second direction D2, so that it is possible to control the light output angle in the second direction D2. This is because the viewing angle in the first direction D1 has a very narrow characteristic, and when the viewing angle is set to an angle θ of 1.5° or more and 20° or less while maintaining that state, the light transmittance in the second direction D2 is rapidly reduced.

[0194] Therefore, when the optical sheet of the present embodiment is used in a display device, it is possible to control the light emission angle in the left-right direction and the up-down direction of the display device. More specifically, when the optical sheet is used as an optical sheet for a display device disposed in front of the passenger seat of a car, it is possible to control the emission of image light to the driver's side and also to control the reflection of the image light on the windshield.

[0195] Other features of the optical sheet in this embodiment are similar to those in "A-1. Optical sheet (first embodiment)" described above, and therefore will not be described here.

[0196] B-3. ​​Surface light source device (fifth embodiment) As shown in, for example, FIGS. 5 to 7, surface light source device 20 of the present embodiment includes optical sheet 10E of the fifth embodiment described above and light source 25 that emits light incident on optical sheet 10E.

[0197] The details of FIGS. 5 to 7 are described above in the section "B-1. Surface light source device (first embodiment)," so description thereof will be omitted here.

[0198] The light source and other members of the surface light source device are described above in the section "B-1. Surface light source device (first embodiment)," so description thereof will be omitted here.

[0199] C-5. Display device (fifth embodiment) The display device of this embodiment includes the optical sheet of the above-mentioned fifth embodiment and a display panel.

[0200] The display device of this embodiment has two further embodiments. The display device of this embodiment includes a surface light source device, and the surface light source device may include the above-mentioned optical sheet. In the display device of this embodiment, the above-mentioned optical sheet may be disposed on the viewer's side of the display panel.

[0201] C-5-1. Display device (first example of the fifth embodiment) The display device of this embodiment includes a surface light source device including the optical sheet of the fifth embodiment described above, and a display panel laminated on the surface light source device.

[0202] 5 to 7 are schematic plan views and cross-sectional views showing an example of a display device 50I of this embodiment. As FIG. 5 to FIG. 7 have been described in the above section "B-1. Surface light source device (first embodiment)", description thereof will be omitted here.

[0203] 1. Surface light source device The surface light source device has been described above in the section "B-3. Surface light source device (fifth embodiment)," so description thereof will be omitted here.

[0204] 2. Display panels and other components The display panel and other members have been described above in the section "C-1-1. Display device (first example of first embodiment)," and therefore description thereof will be omitted here.

[0205] 3.Applications The use of the display device in this embodiment is similar to that described in the above section "C-1-1. Display device (first example of first embodiment)," and therefore a description thereof will be omitted here.

[0206] C-5-2. Display device (second example of the fifth embodiment) The display device of this embodiment includes a display panel, and the optical sheet of the above-mentioned fifth embodiment, which is disposed on the viewer's side of the display panel.

[0207] 9 is a schematic plan view and a cross-sectional view showing an example of a display device 50J of this embodiment. FIG. 9 has been described in the above section "C-1-2. Display device (second example of the first embodiment)", so description here is omitted. As shown in FIG. 9, the display device 50J of this embodiment is disposed such that the base layer 1 of the optical sheet 10I is on the observer (passenger seat) side with respect to the optical function layer 2.

[0208] 1. Optical sheets The optical sheet has been described above in the section "A-3. Optical Sheet (Fifth Embodiment)," so a description thereof will be omitted here.

[0209] 2. Display panels and other components The display panel and other members are described above in the section "C-1-2. Display device (second example of first embodiment)," so description thereof will be omitted here.

[0210] 3.Applications The use of the display device in this embodiment is similar to that described in the above section "C-1-1. Display device (first example of first embodiment)," and therefore a description thereof will be omitted here.

[0211] A-4. Optical sheet (sixth embodiment) The optical sheet 10F of this embodiment includes a base layer 1 and an optical functional layer 2 laminated on one surface of the base layer 1, as shown in, for example, FIG. 1, FIG. 3, FIG. 4, and FIG. 10. The optical sheet 10F of this embodiment has a rectangular shape having a pair of first sides L1 extending in a first direction and a pair of second sides L2 extending in a second direction in a plan view. The optical functional layer 2 has a plurality of light transmitting parts 3 having a predetermined cross section and extending in one direction, and a light absorbing part 4 formed between adjacent light transmitting parts 3, and the predetermined cross section of the light transmitting part 3 is a trapezoid, and the short upper base is the light incident side. The optical sheet 10B is an optical sheet for a display device disposed in front of the passenger seat of a vehicle, and the extension direction of the light transmitting part 3 has an angle of 1.5° or more and 20° or less with respect to the second direction D2.

[0212] 1, 3, and 4 are described in detail in the above section "A-1. Optical sheet (first embodiment)", and therefore will not be described here. Also, FIG. 10 is described in the above section "A-3. Optical sheet (fifth embodiment)", and therefore will not be described here.

[0213] The optical sheet in this embodiment includes an optical functional layer having light transmitting portions and light absorbing portions extending in a predetermined direction and having a predetermined cross section, and thereby can reduce the light transmittance in a direction tilted at ±20° toward the first direction with respect to the third direction. Specifically, when the light transmittance in the third direction is taken as 100%, the relative transmittance, which is the ratio of the light transmittance in a direction tilted at ±20° toward the first direction with respect to the third direction, can be set to 10% or less.

[0214] Furthermore, when the light output angle in the first direction D1 is controlled, the extension direction of the light transmitting section 3 has an angle θ with respect to the second direction D2 that is greater than or equal to 1.5° and less than or equal to 20°, making it possible to control the light output angle in the second direction D2.

[0215] Therefore, when the optical sheet of the present embodiment is used in a display device, it is possible to control the light emission angle in the left-right direction and the up-down direction of the display device. More specifically, when the optical sheet is used as an optical sheet for a display device disposed in front of the passenger seat of a car, it is possible to control the emission of image light to the driver's side, and also possible to control the reflection of the image light on the windshield in front of the passenger seat.

[0216] The optical sheet in this embodiment is an optical sheet for a display device disposed in front of the passenger seat of a vehicle.

[0217] Other features of the optical sheet in this embodiment are similar to those in "A-1. Optical sheet (first embodiment)" described above, and therefore will not be described here.

[0218] B-4. Surface light source device (sixth embodiment) 5 to 7, the surface light source device 20 of the present embodiment includes the optical sheet 10F of the sixth embodiment described above and a light source 25 that emits light incident on the optical sheet 10F. The surface light source device of the present embodiment is used in a display device for a passenger seat.

[0219] The details of FIGS. 5 to 7 are described above in the section "B-1. Surface light source device (first embodiment)," so description thereof will be omitted here.

[0220] The light source and other members of the surface light source device are described above in the section "B-1. Surface light source device (first embodiment)," so description thereof will be omitted here.

[0221] C-6. Display device (sixth embodiment) The display device of this embodiment includes the optical sheet of the sixth embodiment described above and a display panel.

[0222] The display device of this embodiment has two further embodiments. The display device of this embodiment includes a surface light source device, and the surface light source device may include the above-mentioned optical sheet. In the display device of this embodiment, the above-mentioned optical sheet may be disposed on the viewer's side of the display panel.

[0223] C-6-1. Display device (first example of the sixth embodiment) The display device of this embodiment includes a surface light source device including the optical sheet of the sixth embodiment described above, and a display panel laminated on the surface light source device.

[0224] 5 to 7 are schematic plan views and cross-sectional views showing an example of a display device 50K of this embodiment. As FIG. 5 to FIG. 7 have been described in the above section "B-1. Surface light source device (first embodiment)", description thereof will be omitted here.

[0225] 1. Surface light source device The surface light source device has been described above in the section "B-4. Surface light source device (sixth embodiment)," so description thereof will be omitted here.

[0226] 2. Display panels and other components The display panel and other members have been described above in the section "C-1-1. Display device (first example of first embodiment)," and therefore description thereof will be omitted here.

[0227] 3.Applications The use of the display device in this embodiment is similar to that described in the above section "C-1-1. Display device (first example of first embodiment)," and therefore a description thereof will be omitted here.

[0228] C-6-2. Display device (second example of the sixth embodiment) The display device of this embodiment includes a display panel, and the optical sheet of the above-described sixth embodiment, which is disposed on the viewer's side of the display panel.

[0229] 9 is a schematic plan view and a cross-sectional view showing an example of a display device 50L of this embodiment. Since FIG. 9 has been described in the above section "C-1-2. Display device (second example of the first embodiment)", a description thereof will be omitted here.

[0230] 1. Optical sheets The optical sheet is similar to the optical sheet described in the above section "C-6-1. Display device (first example of sixth embodiment)," and therefore a description thereof will be omitted here.

[0231] 2. Display panels and other components The display panel and other members are described above in the section "C-1-2. Display device (second example of first embodiment)," so description thereof will be omitted here.

[0232] 3.Applications The use of the display device in this embodiment is similar to that described in the above section "C-1-1. Display device (first example of first embodiment)," and therefore a description thereof will be omitted here.

[0233] C-7. Display device (seventh embodiment) The display device of this embodiment is a display device comprising an optical sheet and a display panel, wherein the optical sheet comprises a base layer and an optical functional layer laminated on one side of the base layer, the optical functional layer has a plurality of light-transmitting portions having a predetermined cross-section and extending in one direction, and light-absorbing portions formed between adjacent light-transmitting portions, the predetermined cross-section of the light-transmitting portions being trapezoidal with a shorter upper base being the light-entering side, and when the display device is installed, the optical sheet has a relative transmittance of 10% or less, which is the ratio of the light transmittance in a direction inclined ±20° left and right from the normal direction when the light transmittance in the normal direction of the main surface of the optical sheet is 100%, and the extension direction of the light-transmitting portions as viewed from the normal direction has an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0234] The display device of this embodiment has two further embodiments. The display device of this embodiment includes a surface light source device, and the surface light source device may include the above-mentioned optical sheet. In the display device of this embodiment, the above-mentioned optical sheet may be disposed on the viewer's side of the display panel.

[0235] C-7-1. Display device (first example of the seventh embodiment) 5 to 7 are schematic plan views and cross-sectional views showing an example of the display device of this embodiment. Also, FIGS. 1, 3, 4, and 10 are schematic perspective views, cross-sectional views, and plan views showing an example of an optical sheet in the display device of this embodiment. As shown in FIGS. 5 to 7, the display device 50M of this embodiment includes a surface light source device 20 including an optical sheet 10G, and a liquid crystal panel 15 laminated on the surface light source device 20. As shown in FIGS. 1, 3, 4, and 10, the optical sheet 10G of this embodiment includes a base layer 1 and an optical functional layer 2 laminated on one surface of the base layer 1, and the optical functional layer 2 has a plurality of light transmitting portions 3 having a predetermined cross section and extending in one direction, and a light absorbing portion 4 formed between adjacent light transmitting portions 3, and the predetermined cross section of the light transmitting portion 3 is a trapezoid, and the short upper base is the light incident side. 10, when the display device 50M is installed, the optical sheet 10G has a relative transmittance of 10% or less, which is the ratio of the light transmittance in a direction inclined by ±20° left and right from the normal direction N, when the light transmittance in the normal direction N (third direction D3 in FIGS. 1, 3, 4, and 10) of the main surface S of the optical sheet is taken as 100%. Also, as shown in FIG 3, when the display device 50M is installed, the extension direction of the light transmitting portion 3 of the optical sheet 10G as viewed from the normal direction N has an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0236] Details of Fig. 1, Fig. 3, and Fig. 4 have been described above in the section "A-1. Optical sheet (first embodiment)", so their description will be omitted here. Fig. 10 has been described above in the section "A-3. Optical sheet (fifth embodiment)", so their description will be omitted here. Figs. 5 to 7 have been described above in the section "B-1. Surface light source device (first embodiment)", so their description will be omitted here.

[0237] The display device 50M of this embodiment has a predetermined optical sheet 10G. In the optical sheet 10G of this embodiment, when the display device is installed, the relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±20° to the left and right with respect to the normal direction, is equal to or less than a predetermined value, so that it is possible to control the light output angle in the left and right direction of the display device. Furthermore, in a state in which the light output angle in the left and right direction is controlled, the extension direction of the light transmitting portion as viewed from the normal direction has an angle θ in a predetermined range with respect to the vertical direction, so that it is possible to control the light output angle in the up and down direction of the display device.

[0238] Therefore, the display device can control the light emission angle in the left-right and up-down directions. More specifically, when the display device is placed in front of the passenger seat of a car, it is possible to control the emission of image light to the driver's side and also to control the reflection of the image light on the windshield in front of the passenger seat.

[0239] 1. Surface light source device The surface light source device includes a predetermined optical sheet. As shown in Fig. 1, Fig. 3, Fig. 4, and Fig. 10, when a display device is installed, the optical sheet 10G in this embodiment has a relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±20° to the left and right from the normal direction N, of 10% or less when the light transmittance in the normal direction N (the third direction D3 in Fig. 1, Fig. 3, Fig. 4, and Fig. 10) of the main surface of the optical sheet is 100%. The relative transmittance of the light is preferably 5% or less.

[0240] Furthermore, in the optical sheet of this embodiment, when the display device is installed, the extension direction of the light transmitting portion as viewed from the normal direction has an angle of 1.5° or more and 20° or less with respect to the vertical direction. The angle θ is 1.5° or more, and may be 5° or more, or 10° or more. On the other hand, the angle θ may be 20° or less and 15° or less. When the angle θ is in the above range, it is possible to control the light output angle in the left-right direction. In addition, in FIG. 1 and FIG. 3, the light transmitting portion 3 has an angle θ on the right side (+D1 side) with respect to the vertical direction. In this case, it is preferable that the left side (-D1 side) is the driver's seat side. On the other hand, the light transmitting portion 3 may have an angle θ on the left side (-D1 side) with respect to the second direction D2. In this case, it is preferable that the right side (+D1 side) is the driver's seat side.

[0241] The characteristics of the optical sheet having the above optical properties and other characteristics in this embodiment are similar to those of the above-mentioned "A-1. Optical sheet (first embodiment)", so the description here will be omitted. The other members of the surface light source device are described in the above "B-1. Surface light source device (first embodiment)", so the description here will be omitted.

[0242] 2. Display panels and other components The display panel and other members have been described above in the section "C-1-1. Display device (first example of first embodiment)," and therefore description thereof will be omitted here.

[0243] 3.Applications The use of the display device in this embodiment is similar to that of "C-1-1. Display device (first example of first embodiment)" described above, and therefore a description thereof will be omitted here.

[0244] C-7-2. Display device (second example of the seventh embodiment) FIG. 9 is a schematic plan view and a cross-sectional view showing an example of the display device of this embodiment. Also, FIG. 1, FIG. 3, FIG. 4, and FIG. 10 are schematic perspective views, cross-sectional views, and plan views showing an example of an optical sheet in the display device of this embodiment. As shown in FIG. 9, the display device 50N of this embodiment includes a display panel 30 and an optical sheet 10G arranged on the observer side of the display panel 30. As shown in FIG. 1, FIG. 3, FIG. 4, and FIG. 10, the optical sheet 10G of this embodiment includes a base layer 1 and an optical functional layer 2 laminated on one surface of the base layer 1, and the optical functional layer 2 has a plurality of light transmitting parts 3 having a predetermined cross section and extending in one direction, and a light absorbing part 4 formed between adjacent light transmitting parts 3, and the predetermined cross section of the light transmitting part 3 is a trapezoid, and the short upper base is the light incident side. 10, when the display device 50N is installed, the optical sheet 10G has a relative transmittance of 10% or less, which is the ratio of the light transmittance in a direction inclined by ±20° left and right from the normal direction N, when the light transmittance in the normal direction N (the third direction D3 in FIGS. 1 to 4) of the main surface S of the optical sheet is taken as 100%. Also, as shown in FIG 3, when the display device 50N is installed, the extension direction of the light transmitting portions 3 of the optical sheet 10G as viewed from the normal direction N has an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0245] Details of Figs. 1, 3, and 4 are described above in the section "A-1. Optical sheet (first embodiment)", so their description will be omitted here. Fig. 10 is described above in the section "A-3. Optical sheet (fifth embodiment)", so their description will be omitted here. Fig. 9 is described above in the section "C-1-2. Display device (second example of first embodiment)", so their description will be omitted here.

[0246] 1. Optical sheets The optical sheet is similar to the optical sheet described in the above section "C-7-1. Display device (first example of seventh embodiment)," and therefore a description thereof will be omitted here.

[0247] 2. Display panels and other components The display panel and other members are described above in the section "C-1-2. Display device (second example of first embodiment)," so description thereof will be omitted here.

[0248] 3.Applications The use of the display device in this embodiment is similar to that of "C-1-1. Display device (first example of first embodiment)" described above, and therefore a description thereof will be omitted here.

[0249] C-8. Display device (eighth embodiment) The display device of this embodiment comprises an optical sheet and a display panel, and is disposed in front of the passenger seat of a vehicle, the optical sheet comprises a base material layer and an optical functional layer laminated on one side of the base material layer, the base material layer being a resin base material, the optical functional layer has a plurality of light-transmitting portions having a predetermined cross-section and extending in one direction, and light-absorbing portions formed between adjacent light-transmitting portions, the predetermined cross-section of the light-transmitting portions being trapezoidal with a shorter upper base being the light incident side, and the optical sheet is a display device in which, when the display device is disposed in front of the passenger seat of a vehicle, the extension direction of the light-transmitting portions as viewed from the normal direction of the main surface of the optical sheet has an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0250] The display device of this embodiment has two further embodiments. The display device of this embodiment includes a surface light source device, and the surface light source device may include the above-mentioned optical sheet. In the display device of this embodiment, the above-mentioned optical sheet may be disposed on the viewer's side of the display panel.

[0251] C-8-1. Display device (first example of eighth embodiment) 5 to 7 are schematic plan views and cross-sectional views showing an example of the display device of this embodiment. Also, FIG. 1, FIG. 3, FIG. 4, and FIG. 10 are schematic perspective views, cross-sectional views, and plan views showing an example of an optical sheet in the display device of this embodiment. As shown in FIG. 5 to FIG. 7, the display device 50O in this embodiment is a display device that includes a surface light source device 20 including an optical sheet 10H and a liquid crystal panel 15 laminated on the surface light source device 20, and is disposed in front of the passenger seat of a car. As shown in FIG. 1, FIG. 3, FIG. 4, and FIG. 10, the optical sheet 10H in this embodiment includes a base material layer 1 and an optical functional layer 2 laminated on one surface of the base material layer 1, the base material layer 1 is a resin base material, the optical functional layer 2 has a plurality of light transmitting portions 3 having a predetermined cross section and extending in one direction, and a light absorbing portion 4 formed between adjacent light transmitting portions 3, and the predetermined cross section of the light transmitting portion 3 is a trapezoid, and the short upper base is the light incident side. When the display device is installed in front of the passenger seat of a vehicle, the extension direction of the light-transmitting portion 3 of the optical sheet 10H as viewed from the normal direction N (the third direction D3 in Figures 1 to 4) of the main surface of the optical sheet 10H has an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0252] The display device 50O in this embodiment has a predetermined optical sheet 10H. The optical sheet 10H in this embodiment includes an optical functional layer having a light transmitting portion and a light absorbing portion extending in a predetermined direction and having a predetermined cross section, so that when the display device is installed in front of the passenger seat of a car, the light transmittance in a direction inclined by ±20° to the left and right with respect to the normal direction can be reduced. Specifically, when the light transmittance in the normal direction is 100%, the relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±20° to the left and right with respect to the normal direction, can be 10% or less. Therefore, it is possible to control the light output angle in the left and right direction of the display device.

[0253] Furthermore, in a state where the light emission angle in the left-right direction is controlled, the extension direction of the light transmitting portion as viewed from the normal direction has an angle θ in a predetermined range with respect to the vertical direction, so that the light emission angle in the up-down direction of the display device can be controlled. Therefore, the display device of this embodiment can control the emission of image light to the driver's side, and can also control the reflection of the image light on the windshield in front of the passenger seat.

[0254] 1. Surface light source device The surface light source device includes a predetermined optical sheet. The optical sheet 10H in this embodiment extends in a predetermined direction and includes an optical functional layer having a light transmitting portion and a light absorbing portion having a predetermined cross section. As a result, when a display device 50O having a predetermined optical sheet 10H is installed in front of the passenger seat of a car, when the light transmittance in the normal direction N (the third direction D3 in Figs. 1, 3, 4, and 10) of the main surface of the optical sheet 10H is 100%, the relative transmittance, which is the ratio of the light transmittance in a direction inclined ±20° to the left and right from the normal direction N, can be 10% or less. The relative transmittance of the light is preferably 5% or less.

[0255] Furthermore, in the optical sheet of this embodiment, when the display device is installed in front of the passenger seat of the car, the extension direction of the light transmitting portion as viewed from the normal direction has an angle of 1.5° or more and 20° or less with respect to the vertical direction. The angle θ is 1.5° or more, and may be 5° or more, or 10° or more. On the other hand, the angle θ may be 20° or less and 15° or less. When the angle θ is in the above range, it is possible to control the light output angle in the left-right direction. In addition, in FIG. 1 and FIG. 3, the light transmitting portion 3 has an angle θ on the right side (+D1 side) with respect to the vertical direction. In this case, it is preferable that the left side (-D1 side) is the driver's seat side. On the other hand, the light transmitting portion 3 may have an angle θ on the left side (-D1 side) with respect to the vertical direction. In this case, it is preferable that the right side (+D1 side) is the driver's seat side.

[0256] Other features of the optical sheet in this embodiment are the same as those in "A-1. Optical sheet (first embodiment)" above, so the description here will be omitted. Other members of the surface light source device are described in "B-1. Surface light source device (first embodiment)" above, so the description here will be omitted.

[0257] 2. Display panels and other components The display panel and other members have been described above in the section "C-1-1. Display device (first example of first embodiment)," and therefore description thereof will be omitted here.

[0258] 3.Applications The display device in this embodiment is placed in front of the passenger seat of the vehicle. Fig. 8(a) is a schematic diagram of the front of the vehicle interior when the display device 50O in this embodiment is placed in front of the passenger seat of the vehicle. Fig. 8(b) is a plan view for explaining the state of the optical sheet of the display device in Fig. 8(a). In Figs. 8(a) and 8(b), the optical sheet is placed so that the left-right direction is horizontal (left-right direction of the vehicle), the up-down direction is vertical, and the thickness direction is horizontal (front-rear direction of the vehicle). However, the installation posture of the display device is not limited to this.

[0259] C-8-2. Display device (second example of the eighth embodiment) FIG. 9 is a schematic plan view and a cross-sectional view showing an example of the display device of this embodiment. Also, FIG. 1, FIG. 3, FIG. 4, and FIG. 10 are schematic perspective views, cross-sectional views, and plan views showing an example of an optical sheet in the display device of this embodiment. As shown in FIG. 9, the display device 50P of this embodiment includes a display panel 30 and an optical sheet 10H arranged on the observer side of the display panel 30. As shown in FIG. 1, FIG. 3, FIG. 4, and FIG. 10, the optical sheet 10H of this embodiment includes a base layer 1 and an optical functional layer 2 laminated on one surface of the base layer 1, and the optical functional layer 2 has a plurality of light transmitting portions 3 having a predetermined cross section and extending in one direction, and a light absorbing portion 4 formed between adjacent light transmitting portions 3, and the predetermined cross section of the light transmitting portion 3 is a trapezoid, and the short upper base is the light incident side. As shown in FIG. 3, when a display device 50P is installed, the extension direction of the light transmitting portion 3 of the optical sheet 10H as viewed from the normal direction N forms an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0260] Details of Figs. 1, 3, and 4 are described above in the section "A-1. Optical sheet (first embodiment)", so their description will be omitted here. Fig. 10 is described above in the section "A-3. Optical sheet (fifth embodiment)", so their description will be omitted here. Fig. 9 is described above in the section "C-1-2. Display device (second example of first embodiment)", so their description will be omitted here.

[0261] 1. Optical sheets The optical sheet is similar to the optical sheet described in the above section "C-8-1. Display device (first example of eighth embodiment)," and therefore a description thereof will be omitted here.

[0262] 2. Display panels and other components The display panel and other members are described above in the section "C-1-2. Display device (second example of first embodiment)," so description thereof will be omitted here.

[0263] 3.Applications The use of the display device in this embodiment is similar to that of "C-8-1. Display device (first example of eighth embodiment)" above, and therefore a description thereof will be omitted here.

[0264] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits similar effects is included in the technical scope of the present disclosure. EXAMPLES

[0265] The present disclosure will be described in further detail below with reference to examples and comparative examples.

[0266] [Examples 1 to 18 and Comparative Examples 1 to 14] An optical sheet having a base layer and an optical functional layer as shown in Fig. 1 to Fig. 4 was manufactured. At this time, the angle of the light transmitting portion with respect to the second direction (bias angle θ) and the leg inclination angle θ in the trapezoidal cross section were 11 and θ 12 The light incident side aperture ratio, the height Da of the light absorbing portion, the OD value of the light absorbing portion, and the refractive index difference Nt-Nr between the light transmitting portion and the light absorbing portion were changed as shown in Tables 1 and 2. In sample groups 1 to 3, the refractive index Nt of the light transmitting portion was 1.57, and the refractive index difference Nr of the light absorbing portion was 1.54.

[0267] For the obtained optical sheet, the light luminance was measured as described below, and the transmittance and relative transmittance were calculated.

[0268] (Measurement method) First, the optical sheet was not placed, and the luminance of the light of the surface light source (edge-light type surface light source using LED as a light source) alone in the third direction D3 was measured by a viewing angle characteristic measuring device (EZ Contrast XL80 manufactured by ELDIM). Next, the surface light source (edge-light type surface light source using LED as a light source) was placed on the back side (optical functional layer side) of the optical sheet, and the luminance of the light transmitted in the third direction D3 of the optical sheet and the luminance of the light transmitted in a direction inclined ±30° to the first direction D1 side with respect to the third direction D3 were measured on the front side (base layer side) by a viewing angle characteristic measuring device (EZ Contrast XL80 manufactured by ELDIM). Then, the ratio of the luminance of the light transmitted in the third direction D3 of the optical sheet to the luminance of the light of the surface light source alone in the third direction D3 was calculated as the transmittance of the light transmitted in the third direction D3 of the optical sheet. Similarly, the ratio of the brightness of light transmitted in a direction inclined at ±30° toward the first direction D1 with respect to the third direction to the brightness of light in the third direction D3 of the surface light source alone was calculated as the transmittance of light transmitted in a direction inclined at ±30° toward the first direction D1 with respect to the third direction D3. Finally, the relative transmittance was calculated as the ratio of the transmittance of light transmitted in a direction inclined at ±30° toward the first direction D1 with respect to the third direction D3 when the transmittance of the light transmitted in the third direction D3 of the optical sheet was taken as 100%. The results are shown in Tables 1 and 2.

[0269] In addition, in the same manner as described above, the relative transmittance, which is the ratio of the transmittance of light passing through the optical sheet in a direction inclined by ±20° toward the first direction D1 relative to the third direction D3, to the transmittance of light passing through the optical sheet in the third direction D3 being 100%, was calculated.

[0270] The results of measuring the relative transmittance of the optical sheets of Example 4 and Comparative Example 8 are shown in Fig. 12(a) and Fig. 13(a). In Fig. 12(a), the horizontal axis represents the viewing angle in the left-right direction (first direction D1), and the vertical axis represents the ratio (relative transmittance) of light transmittance at each viewing angle in the left-right direction when the light transmittance at a viewing angle of 0° is set to 100%. The optical sheet of Example 4 obtained a relative transmittance of 0.5% at a viewing angle of ±30° in the first direction D1, and a relative transmittance of 5.0% at a viewing angle of ±20° in the first direction D1. On the other hand, the optical sheet of Comparative Example 8 obtained a relative transmittance of 17.8% at a viewing angle of ±30° in the first direction D1, and a relative transmittance of 57.8% at a viewing angle of ±20° in the first direction D1.

[0271] 13(a), the horizontal axis represents the viewing angle in the vertical direction (second direction D2), and the vertical axis represents the ratio of light transmittance (relative transmittance) at each viewing angle in the vertical direction when the light transmittance at a viewing angle of 0° is taken as 100%. The optical sheet of Example 4 achieved a relative transmittance of 18% at a viewing angle of ±30° in the second direction D2. Meanwhile, the optical sheet of Comparative Example 8 achieved a relative transmittance of 31.1% at a viewing angle of ±30° in the second direction D2.

[0272] [Table 1]

[0273] [Table 2]

[0274] [Table 3]

[0275] [Table 4]

[0276] The optical sheets of Example 4 and Comparative Example 8 were used in a display device, and the display device was observed from the front and at an angle from a position where the horizontal viewing angle was about 30°. Fig. 12(b) shows the state of the display device observed. In Comparative Example 8, the image light was visible from a position where the horizontal viewing angle was about 30°, whereas in Example 4, it was confirmed that the image light was not visible from a position where the horizontal viewing angle was about 30°.

[0277] Assuming that the optical sheets of Examples 1 to 18 and Comparative Examples 1 to 14 are used in a display device for a passenger seat, the presence or absence of reflection of image light on the windshield in front of the passenger seat was observed. In Comparative Example 8, reflection of image light on the windshield was observed, but it was confirmed that reflection was suppressed in Example 4 (FIG. 13(b)). In addition, Tables 1 and 2 show the presence or absence of reflection on the windshield when the optical sheets of other Examples and Comparative Examples are used. From Tables 1 and 2, it was confirmed that reflection on the windshield is suppressed when the relative transmittance, which is the ratio of the transmittance of light in a direction inclined ±30° toward the second direction with respect to the third direction when the transmittance of light in the third direction is 100%, is 32% or less.

[0278] That is, the present disclosure provides the following inventions. [1] An optical sheet comprising a base layer and an optical functional layer laminated on one surface of the base layer, the optical sheet has a rectangular shape in a plan view having a pair of first sides extending in a first direction and a pair of second sides extending in a second direction; the optical function layer has a plurality of light transmitting portions having a predetermined cross section and extending in one direction, and a light absorbing portion formed between adjacent light transmitting portions, The predetermined cross section of the light transmitting portion is a trapezoid, and a short upper base is a light incident side, a relative transmittance, which is a ratio of a light transmittance in a direction inclined by ±20° toward the first direction with respect to the third direction, to a light transmittance in a third direction perpendicular to the first direction and the second direction being 100%, is 10% or less; the extending direction of the light transmitting portion has an angle of 1.5° or more and 20° or less with respect to the second direction; [2] An optical sheet comprising a base layer and an optical functional layer laminated on one surface of the base layer, The substrate layer is a resin substrate, the optical sheet has a rectangular shape in a plan view having a pair of first sides extending in a first direction and a pair of second sides extending in a second direction; the optical function layer has a plurality of light transmitting portions having a predetermined cross section and extending in one direction, and a light absorbing portion formed between adjacent light transmitting portions, The predetermined cross section of the light transmitting portion is a trapezoid, and a short upper base is a light incident side, The optical sheet is an optical sheet for a display device disposed in front of a passenger seat of a vehicle, the extending direction of the light transmitting portion has an angle of 1.5° or more and 20° or less with respect to the second direction; [3] The optical sheet according to [2], wherein the relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±20° toward the first direction with respect to the third direction to the light transmittance in a third direction perpendicular to the first direction and the second direction being 100%, is 10% or less. [4] The optical sheet according to any one of [1] to [3], wherein an interface between the light-transmitting portion and the light-absorbing portion forms an angle of 4.5° or more with respect to a normal to a layer surface of the optical functional layer. [5] The optical sheet according to any one of [1] to [4], wherein the optical functional layer has a light incident side aperture ratio of 35% or less. [6] The optical sheet according to any one of [1] to [5], wherein the height of the light absorbing portion is 120 μm or more. [7] The optical sheet according to any one of [1] to [6], wherein the OD value of the light absorbing portion is 3.5 or more. [8] The optical sheet according to any one of [1] to [7], wherein a difference Nt-Nr between a refractive index Nt of the light-transmitting portion and a refractive index Nr of the light-absorbing portion is 0.05 or less. [9] The optical sheet according to any one of [1] to [8], wherein the retardation of the base layer is 3000 nm or more.

[10] [1] to [9], and an optical sheet according to any one of the above. A surface light source device comprising: a light source that emits light incident on the optical sheet.

[11]

[10] A surface light source device according to the present invention; A display device comprising: a display panel laminated on the surface light source device.

[12] A display device comprising an optical sheet and a display panel, The optical sheet includes a base layer and an optical functional layer laminated on one surface of the base layer, the optical function layer has a plurality of light transmitting portions having a predetermined cross section and extending in one direction, and a light absorbing portion formed between adjacent light transmitting portions, The predetermined cross section of the light transmitting portion is a trapezoid, and a short upper base is a light incident side, When the display device is installed, the optical sheet a relative transmittance, which is a ratio of light transmittance in a direction inclined by ±20° to the left or right from the normal direction when the light transmittance in the normal direction to the main surface of the optical sheet is 100%, is 10% or less; a direction in which the light transmitting portion extends as viewed from the normal direction has an angle of 1.5° or more and 20° or less with respect to a vertical direction.

[13] A display device including an optical sheet and a display panel, the display device being disposed in front of a passenger seat of a vehicle, The optical sheet includes a base layer and an optical functional layer laminated on one surface of the base layer, The substrate layer is a resin substrate, the optical function layer has a plurality of light transmitting portions having a predetermined cross section and extending in one direction, and a light absorbing portion formed between adjacent light transmitting portions, The predetermined cross section of the light transmitting portion is a trapezoid, and a short upper base is a light incident side, When the display device is installed in front of the passenger seat of a car, the optical sheet a direction in which the light transmitting portion extends as viewed from a normal direction to a main surface of the optical sheet has an angle of 1.5° or more and 20° or less with respect to a vertical direction.

[14] When the display device is installed in front of the passenger seat of a car, the optical sheet The display device according to

[13] , wherein a relative transmittance, which is the ratio of the light transmittance in a direction inclined ±20° to the left or right from the normal direction to the light transmittance in a normal direction of the main surface of the optical sheet, is 10% or less when the light transmittance in the normal direction is 100%.

[15] The display device according to any one of

[12] to

[14] , wherein the display device comprises a surface light source device, the surface light source device including the optical sheet.

[16] The display device according to any one of

[12] to

[14] , wherein the optical sheet is disposed on a viewer's side of the display panel.

[17] The display device according to

[16] , which is an organic electroluminescence display device.

[18] The display device according to any one of

[12] to

[16] , which is a liquid crystal display device. [Explanation of symbols]

[0279] 1... Base material layer 2… Optical functional layer 3... Light transmitting part 4... Light absorbing part 10...Optical sheet 15... LCD panel 20… Surface light source device 21…Light guide plate 25… light source 26... Light diffusion plate 27... Prismatic layer 28… Reflective polarizing plate 50…Display device

Claims

1. An optical sheet comprising a base layer and an optical functional layer laminated on one surface of the base layer, the optical sheet has a rectangular shape in a plan view having a pair of first sides extending in a first direction and a pair of second sides extending in a second direction; the optical function layer has a plurality of light transmitting portions having a predetermined cross section and extending in one direction, and a light absorbing portion formed between adjacent light transmitting portions, The predetermined cross section of the light transmitting portion is a trapezoid, and a short upper base is a light incident side, a relative transmittance, which is a ratio of a light transmittance in a direction inclined by ±20° toward the first direction with respect to the third direction, to a light transmittance in a third direction perpendicular to the first direction and the second direction being 100%, is 10% or less; The extension direction of the light transmitting portion has an angle of 1.5° or more and 20° or less with respect to the second direction, an angle formed by an interface between the light transmitting portion and the light absorbing portion and a normal line to a layer surface of the optical functional layer is equal to or greater than 4.0° and is equal to or smaller than 6.5°; the aperture ratio of the optical functional layer on the light incident side is 25% or more and 35% or less; The optical sheet, wherein the height of the light absorbing portion is 120 μm or more.

2. The optical sheet according to claim 1 , wherein the OD value of the light absorbing portion is 3.5 or more.

3. 2. The optical sheet according to claim 1, wherein a difference Nt-Nr between a refractive index Nt of said light-transmitting portion and a refractive index Nr of said light-absorbing portion is 0.05 or less.

4. The optical sheet according to claim 1 , wherein the retardation of the base layer is 3000 nm or more.

5. An optical sheet according to any one of claims 1 to 4; a light source that emits light incident on the optical sheet.

6. The surface light source device according to claim 5 , A display device comprising: a display panel laminated on the surface light source device.

Images