Optical sheet, surface light source device, and display device

Abstract

To provide an optical sheet that makes it possible to obtain a display device capable of controlling emission of video light in a vertical direction and a horizontal direction.SOLUTION: An optical sheet 10 comprises a base material layer 1, and an optical function layer 2 stacked on one surface of the base material layer. The optical sheet, in a plane view, has a rectangular shape 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 transmission parts 3 each having a predetermined cross section and extending in one direction; and light absorption parts 4 formed between the adjacent light transmission parts. The predetermined cross sections of the light transmission parts are trapezoids, and short upper bases are made to be a light incidence side. When a transmissivity of light in a third direction orthogonal to the first direction and the second direction is assumed to be 100%, a relative transmissivity being a ratio of a transmissivity of light in a direction inclined by ±20° to a first direction side with respect to the third direction is 10% or less.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Display devices such as televisions and monitors of personal computers include a video source that emits video to be displayed, and an optical sheet that enhances the quality of the video light and provides it to the observer side (for example, Patent Documents 1 to 3).

[0003] The emission direction of the video light is often the front and a viewing angle at a predetermined angle up, down, left, and right from the front. As a result, the video projected on the screen can be viewed not only from the front but also from a position having a certain angle. On the other hand, depending on the need, such as preventing peeping, the front direction is set as the main emission direction and the viewing angle is restricted. An optical sheet for this purpose is disclosed in, for example, Patent Document 4.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, a display device for the purpose of entertainment etc. of a person sitting in the passenger seat may be arranged in front of the passenger seat of a vehicle such as an automobile. In such a display device for the passenger seat, it is required to control the emission of video light to the driver side so as not to interfere with the driving by the driver. However, when a conventional optical sheet is mounted on the display device for the passenger seat, when the light transmittance (%) in the front is set to 100%, for example, the relative transmittance which is the ratio of the light transmittance (%) in the direction inclined by ±30° in the left - right direction from the front is about 10%, and the relative transmittance which is the ratio of the light transmittance (%) in the direction inclined by ±20° in the left - right direction from the front is about 55%, and the light emission to the driver side is visually recognized. In the case of a right - hand drive vehicle, the display device for the passenger seat is generally arranged in a direction inclined at least about 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 display device for the passenger seat is generally arranged in a direction inclined at least about 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, for example, along one side direction of the sheet (the second direction D2 in Fig. 11(a)), and has a layer (optical function layer 32) in which a light - transmitting portion (light - transmitting portion 33) and a light - absorbing portion (light - absorbing portion 34) are alternately arranged in parallel along the sheet surface. Such an optical sheet provides a viewing - angle control only in the direction orthogonal to the extending direction of the light - transmitting portion 33 and the light - absorbing portion 34 (the first direction D1 in Fig. 11(a)), and it has been difficult to control the viewing angle in the parallel direction (the second direction D2 in Fig. 11(a)). Therefore, as shown in Fig. 11(b), when the optical sheet 90 is used for the display device 100 for the passenger seat, the video light may enter the passenger - side of the vehicle's windshield. Therefore, it is also required to control the reflection (in the up - down direction) on the windshield in front of the passenger seat. In Fig. 11(b), members other than the optical sheet of the display device 100 are omitted.

[0007] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide an optical sheet capable of obtaining a display device capable of controlling the emission of video light in the vertical and horizontal directions. Specifically, when used as an optical sheet for a display device disposed in front of the passenger seat of a vehicle, it is possible to control the emission of video light toward the driver side, and it is possible to control the reflection of video light on the windshield in front of the passenger seat. An object is to provide an optical sheet capable of obtaining a display device.

Means for Solving the Problems

[0008] An embodiment of the present disclosure is an optical sheet including a base material layer and an optical functional layer laminated on one surface of the base material layer. The optical sheet has a rectangular shape having a pair of first sides extending in a first direction and a pair of second sides extending in a second direction in a plan view. The optical functional layer has a plurality of light transmission portions having a predetermined cross section and extending in one direction, and light absorption portions formed between adjacent light transmission portions. The predetermined cross section of the light transmission portion is trapezoidal, with the short upper base being the light incident side. When the light transmittance in a third direction orthogonal to the first direction and the second direction is 100%, the relative transmittance, which is the ratio of the light transmittance in a direction inclined by ±20° toward the first direction side with respect to the third direction, is 10% or less. The extending direction of the light transmission portion has an angle of 1.5° or more and 20° or less with respect to the second direction.

[0009] Other embodiments of the present disclosure are optical sheets including a base material layer and an optical functional layer laminated on one surface of the base material layer. The base material layer is a resin base material. The optical sheet has a rectangular shape having a pair of first sides extending in a first direction and a pair of second sides extending in a second direction in a plan view. The optical functional layer has a plurality of light transmission portions having a predetermined cross-section and extending in one direction, and light absorption portions formed between adjacent light transmission portions. The predetermined cross-section of the light transmission portion is trapezoidal, with the short upper base on the light incident side. The optical sheet is an optical sheet for a display device disposed in front of the passenger seat of a vehicle, and the extending direction of the light transmission portion has an angle of 1.5° or more and 20° or less with respect to the second direction.

[0010] Other embodiments of the present disclosure are surface light source devices including the above-described optical sheet and a light source that emits light incident on the optical sheet.

[0011] Other embodiments of the present disclosure are display devices including the above-described surface light source device and a display panel laminated on the surface light source device.

[0012] Other embodiments of the present disclosure are display devices including an optical sheet and a display panel. The optical sheet includes a base material layer and an optical functional layer laminated on one surface of the base material layer. The optical functional layer has a plurality of light transmission portions having a predetermined cross-section and extending in one direction, and light absorption portions formed between adjacent light transmission portions. The predetermined cross-section of the light transmission portion is trapezoidal, with the short upper base on the light incident side. When the display device is installed, the optical sheet has a relative transmittance, which is the ratio of the light transmittance in a direction inclined ±20° from the normal direction to the left and right directions when the light transmittance in the normal direction of the main surface of the optical sheet is 100%, of 10% or less, and the extending direction of the light transmission portion viewed from the normal direction has an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0013] Other embodiments of the present disclosure are display devices including an optical sheet and a display panel, and are disposed in front of the passenger seat of a vehicle. The optical sheet includes a base material layer and an optical functional layer laminated on one surface of the base material layer. The base material layer is a resin base material, and the optical functional layer includes a plurality of light transmission portions having a predetermined cross section and extending in one direction, and light absorption portions formed between adjacent light transmission portions. The predetermined cross section of the light transmission portion is trapezoidal, with the shorter upper base on the light incident side. When the display device is installed in front of the passenger seat of the vehicle, the optical sheet has a display device in which the extending direction of the light transmission portion, 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.

Advantages of the Invention

[0014] In the present disclosure, it is possible to provide an optical sheet that can obtain a display device capable of controlling the emission of video light in the vertical and horizontal directions. Further, in the present disclosure, when used as an optical sheet for a display device disposed in front of the passenger seat of a vehicle, it is possible to control the emission of video light toward the driver side and to control the reflection of video light on the windshield in front of the passenger seat, and it is possible to provide an optical sheet that can obtain a display device.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings and the like. However, the present disclosure can be implemented in many different modes and is not construed as being limited to the description of the embodiments illustrated below. Also, for the purpose of making the description clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual form, but this is merely an example and does not limit the interpretation of the present disclosure. Further, in this specification and each figure, elements that are the same as those described above with respect to the previously shown figures may be denoted by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0017] In this specification, when expressing the manner of disposing one member on another member, if simply denoted as "on" or "below", unless otherwise specified, it includes both the case where another member is disposed directly above or directly below in contact with a certain member, and the case where another member is disposed above or below a certain member with yet another member interposed therebetween. Also, in this specification, when expressing the manner of disposing one member on the surface of another member, if simply denoted as "on the surface side" or "on the surface", unless otherwise specified, it includes both the case where another member is disposed directly above or directly below in contact with a certain member, and the case where another member is disposed above or below a certain member with yet another member interposed therebetween.

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

[0019] A-1. Optical Sheet (First Embodiment) The optical sheet of this embodiment is an optical sheet including a base material layer and an optical functional layer laminated on one surface of the base material layer. The optical sheet has a rectangular shape having a pair of first sides extending in a first direction and a pair of second sides extending in a second direction in a plan view. The optical functional layer has a plurality of light transmission portions having a predetermined cross-section and extending in one direction, and light absorption portions formed between adjacent light transmission portions. The predetermined cross-section of the light transmission portion is trapezoidal, with the short upper base being the light incident side. The relative transmittance, which is the ratio of the transmittance of light in a direction inclined by ±30° to the first direction side with respect to the third direction when the transmittance of light in the third direction orthogonal to the first direction and the second direction is 100%, is 1% or less. The extending direction of the light transmission portion has an angle of 1.5° or more and 20° or less with respect to the second direction.

[0020] The optical sheet of this embodiment will be described with reference to the drawings. FIG. 1 is a schematic perspective view showing an example of the optical sheet of this embodiment. Further, FIG. 2 shows a cross-sectional view of the optical sheet cut along the line indicated by I-I in FIG. 1. FIG. 3 is a plan view of the optical sheet shown in FIG. 1 as viewed along the direction (-D3 direction) from the base material layer 1 toward the optical function layer 2. FIG. 4 is an enlarged cross-sectional view of the optical sheet shown in FIG. 2. Among the third directions D3, the direction from the optical function layer 2 toward the base material layer 1 is defined as the +D3 direction, and the direction from the base material layer 1 toward the optical function layer 2 is defined as the -D3 direction. FIGS. 1 to 3 also show the directions (vertical direction and horizontal direction) in the posture in which the display device is installed when the optical sheet is used in the display device, but the installation posture is not limited to this. For example, when the optical sheet is used in the display device, as shown in FIG. 1, the display device is preferably arranged in a posture such that the first direction D1 is the horizontal direction and the second direction D2 is the vertical direction, but is not limited to this posture. Hereinafter, each member will be described.

[0021] As shown in FIGS. 1 to 4, the optical sheet 10A of this embodiment includes a base material layer 1 formed in a sheet shape and an optical function layer 2 provided on one surface of the base material layer 1. The base material layer 1 and the optical function layer 2 are laminated along the third direction D3. Further, as shown in FIG. 3, the optical sheet 10A in this embodiment has a rectangular shape 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 in plan view.

[0022] The optical function layer 2 has a plurality of light transmission portions 3 having a predetermined cross-section and extending in one direction, and light absorption portions 4 formed between adjacent light transmission portions 3. As shown in FIG. 2, the cross-section of the light transmission portion 3 cut along the D1-D3 plane is trapezoidal, and the short 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 the direction inclined by ±30° with respect to the first direction D1 side with respect to the third direction D3, is 1% or less. Further, as shown in FIG. 3, the extending direction of the light transmission portion 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° to the first direction side with respect to the third direction D3, is equal to or less than a predetermined value. Therefore, it is possible to control the light emission angle in the first direction D1. Further, in a state where the light emission angle in the first direction D1 is controlled, since the extending direction of the light transmission portion 3 has an angle θ of 1.5° or more and 20° or less with respect to the second direction D2, it is possible to control the light emission angle in the second direction D2. This is because the viewing angle in the first direction D1 has a very narrow characteristic, and when an angle θ of 1.5° or more and 20° or less is given while maintaining that state, the light transmittance in the second direction D2 rapidly decreases.

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

[0025] For example, by overlapping and using the conventional optical sheet 90 shown in FIG. 11 in two orthogonal directions, it is conceivable to control the light emission angle in the second direction D2 while controlling the light emission angle in the first direction D1. However, with this method, the light transmittance decreases, and the brightness of the display device decreases.

[0026] On the other hand, according to the optical sheet 10A of the present embodiment, it is possible to control the light emission angle in the second direction D2 while controlling the light emission angle in the first direction D1 with a single sheet. Therefore, it is possible to suppress a reduction in light transmittance.

[0027] 1. Optical functional layer The optical sheet in this embodiment includes a base material layer and an optical functional layer laminated on one surface of the base material layer. When the optical sheet is used in a display device, the optical functional layer is arranged to be on the light source side, and the base material layer is arranged to be on the observer side.

[0028] As shown in FIG. 1, the optical functional layer 2 is a layer laminated on one surface of the base material layer 1, and a light transmission portion 3 and a light absorption portion 4 are alternately arranged in the first direction D1 along the layer surface. In the cross section shown in FIG. 2, the optical functional layer 2 includes a light transmission portion 3 having a substantially trapezoidal shape and a light absorption portion 4 formed between two adjacent light transmission portions 3 and having a substantially trapezoidal cross section. The light incident on the optical sheet 10A enters the optical functional layer 2 from the incident surface Pin, and exits from the exit surface Pout except for a part of it.

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

[0030] Among the light that enters obliquely into the light transmission part 3 of the optical functional layer 2 at an incident angle greater than 0°, at least a part of the light Lc that travels obliquely inside the light transmission part 3 and reaches the side surface of the light absorption part 4 is reflected by the side surface of the light absorption part 4, changes its traveling direction to the front direction side, is condensed, and passes through the light transmission part 3. At this time, if the refractive index of the light absorption part 4 is set to be smaller than the refractive index of the light transmission part 3, the light Lc that reaches the side surface of the light absorption part 4 at an incident angle equal to or greater than the critical angle is totally reflected without being absorbed by the light absorption part 4. Therefore, the light transmittance is improved by the total reflection action.

[0031] Among the light that enters obliquely into the light transmission part 3 of the optical functional layer 2 at an incident angle greater than 0°, the light Ld that travels obliquely inside the light transmission part 3 and reaches the side surface of the light absorption part 4 with an incident angle smaller than that of the light Lc with respect to the side surface is partially reflected at the side surface of the light absorption part 4, and the rest is absorbed by the light absorption part 4.

[0032] The light transmission part 3 is a part whose main function is to transmit light. As shown in FIG. 2, in cross-section, it is an element having a substantially trapezoidal cross-sectional shape with a long lower base on the substrate layer 1 side and a short upper base on the opposite side. The light transmission part 3 maintains this cross-section along the layer surface of the substrate layer 1, extends in one direction (a direction forming an angle θ with respect to the second direction D2), and is arranged at a predetermined interval in a direction different from the extending direction (the first direction D1).

[0033] The relative transmittance of the optical sheet in this embodiment, which is the ratio of the transmittance of the light in the direction inclined by ±30° to the first direction side with respect to the third direction when the transmittance of the light in the third direction is 100%, is 1% or less. The relative transmittance of the above light is preferably 0.6% or less, and more preferably 0.4% or less.

[0034] Note that the average value of the relative transmittance of the light in the direction inclined by -30° and the relative transmittance of the light in the direction inclined by +30° is defined as the "relative transmittance of the light in the direction inclined by ±30°".

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

[0036] (Measurement method) First, without placing the optical sheet, measure the luminance of the light in the third direction D3 of the surface light source alone using a viewing angle characteristic measuring device. As the surface light source, an edge-lit type surface light source using an LED as the light source is used. Next, place the surface light source on the back side (optical functional layer side) of the optical sheet, and measure the luminance of the light transmitted through the optical sheet in the third direction D3 and the luminance of the light transmitted in a direction inclined by ±30° toward the first direction D1 with respect to the third direction D3 on the front side (base material layer side) of the optical sheet using a viewing angle characteristic measuring device. Next, calculate the ratio of the luminance of the light transmitted through the optical sheet in the third direction D3 to the luminance of the light in the third direction D3 of the surface light source alone as the transmittance of the light transmitted through the optical sheet in the third direction D3. Similarly, calculate the ratio of the luminance of the light transmitted in a direction inclined by ±30° toward the first direction D1 with respect to the third direction D3 to the luminance of the light in the third direction D3 of the surface light source alone as the transmittance of the light transmitted in a direction inclined by ±30° toward the first direction with respect to the third direction. Finally, calculate the relative transmittance, which is the ratio of the transmittance of the light transmitted in a direction inclined by ±30° toward the first direction D1 with respect to the third direction D3 when the transmittance of the light transmitted through the optical sheet in the third direction D3 is 100%.

[0037] · Transmittance T0 (%) of the light transmitted through the optical sheet in the third direction D3 = {(Luminance of the light emitted from the optical sheet in the third direction D3) / (Luminance of the light in the third direction D3 of the surface light source)} × 100 (%) · Transmittance T of the light transmitted in a direction inclined by ±30° toward the first direction D1 with respect to the third direction D3 30 (%) = {(Luminance of the light emitted from the optical sheet in a direction inclined by ±30° toward the first direction D1 with respect to the third direction D3) / (Luminance of the 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 characteristics can be obtained by adjusting any one or more of the cross-sectional shapes of the light absorption part and the light transmission part, the refractive indices of the light absorption part and the light transmission part, the incident-side aperture ratio, the height of the light absorption part, the OD value of the light absorption part, etc.

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

[0040] Note that the average value of the relative transmittance of light in the direction inclined by -20° and the relative transmittance of light in the direction inclined by +20° is defined as the "relative transmittance of light in the direction inclined by ±20°".

[0041] The relative transmittance, which is the ratio of the transmittance of light in a direction inclined by ±20° toward the first direction with respect to the third direction when the transmittance of light in the third direction is 100%, is obtained in the same manner as the relative transmittance, which is the ratio of the transmittance of light in a direction inclined by ±30° toward the first direction with respect to the third direction when the transmittance of light in the third direction is 100%.

[0042] Further, in the optical sheet of the present embodiment, the relative transmittance, which is the ratio of the transmittance of light in a direction inclined by ±30° toward the second direction with respect to the third direction when the transmittance of light in the third direction is 100%, may be 32% or less, may be 30% or less, or may be 25% or less.

[0043] The relative transmittance, which is the ratio of the transmittance of light in a direction inclined by ±30° toward the second direction with respect to the third direction when the transmittance of light in the third direction is 100%, is obtained in the same manner as the relative transmittance, which is the ratio of the transmittance of light in a direction inclined by ±30° toward the first direction with respect to the third direction when the transmittance of light in the third direction is 100%.

[0044] In the present embodiment, the extending direction of the light transmission 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 may be 10° or more. On the other hand, the angle θ is 20° or less, and may be 15° or less. By the angle θ being within the above range, it becomes possible to control the light emission angle in the second direction. When the display device is installed in the 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 transmission 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. On the other hand, the light transmission 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 extending direction of the light transmission portion 3 is vertical. At this time, the optical sheet may be vertically long or horizontally long. Next, among the angles formed by the vertical side (L2) of the optical sheet 10 and the boundary line BL between the light transmission portion 3 and the light absorption portion 4, the smaller angle is measured. When measuring the above angle, the boundary line BL between the light transmission portion 3 and the light absorption portion 4 on the surfaces of the short upper base of the light transmission portion 3 and the long lower base of the light absorption portion 4 of the optical functional layer 2 is used. Also, as illustrated in FIG. 3, for the two vertical sides (L2a, L2b) of the optical sheet 10, the above angle is measured at two locations each, and the arithmetic mean value of the four measurement values is taken as the angle θ.

[0046] An interval (groove) having a substantially trapezoidal cross section is formed between adjacent light transmission portions 3. Therefore, the interval (groove) has a long lower base on the upper base side (opposite to the base material layer 1 side) of the light transmission portion 3 and a short upper base on the lower base side (base material layer 1 side) of the light transmission portion 3, and has a trapezoidal cross section. The light absorption portion 4 is formed by filling the necessary material to be described later. In FIGS. 1 to 4, adjacent light transmission portions 3 are connected by a sheet-like connecting portion 2a on the long lower base side.

[0047] The light transmission part 3 has a refractive index of Nt. Such a light transmission part 3 can be formed by curing the composition constituting the light transmission part. Details will be described later. The value of the refractive index Nt is not particularly limited. For example, it is preferably 1.50 or more, and more preferably 1.54 or more. On the other hand, the value of the refractive index Nt is, for example, preferably 1.65 or less, and more preferably 1.60 or less. Specifically, the value of the refractive index Nt is preferably 1.50 or more and 1.65 or less, and more preferably 1.54 or more and 1.60 or less. This is because it is easy to obtain a refractive index difference from the light absorption part described later.

[0048] The light absorption part 4 functions as an intermediate part formed in the above-described interval (groove) formed between adjacent light transmission parts 3, and has a cross-sectional shape similar to the cross-sectional shape of the interval. Therefore, the short upper base faces the substrate layer 1 side, and the long lower base faces the side opposite to the substrate layer 1. By setting the short upper base side of the light absorption part as the light emission surface Pout side, a part of the light that travels inside the light transmission part and reaches the interface between the side surface of the light absorption part, specifically, the light absorption part and the light transmission part, is reflected to condense in the front direction, and the light transmittance can be improved.

[0049] The light absorption part 4 has a refractive index of Nr and is configured to be able to absorb light. Specifically, light absorption 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 transmission part 3. In this way, by making the refractive index of the light absorption part 4 smaller than the refractive index of the light transmission part 3, the light incident on the light transmission part 3 under predetermined conditions can be appropriately totally reflected at the interface with the light absorption part 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. For example, it is preferably 1.47 or more, and more preferably 1.51 or more. On the other hand, the value of the refractive index Nr is, for example, preferably 1.65 or less, and more preferably 1.57 or less. Specifically, the value of the refractive index Nr is preferably 1.47 or more and 1.65 or less, and more preferably 1.51 or more and 1.57 or less. This is because it is easy to obtain a refractive index difference from the light transmission part described later.

[0051] The difference Nt - Nr between the refractive index Nt of the light transmissive 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 is moderately suppressed, and 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 vehicle) can be controlled.

[0052] In FIG. 4, the angle θ formed by the interface between the light transmissive portion 3 and the light absorbing portion 4 with respect to the normal of the plane of the optical functional layer 2 11 , θ 12 is shown. The angle θ 11 is the angle formed by the interface 4a on the right side of the light absorbing portion 4 when the optical sheet 10 is arranged with the substrate layer 1 side as the observer side, among the interfaces between the light transmissive portion 3 and the light absorbing portion 4, and the normal of the plane of the optical functional layer 2. The angle θ 12 is the angle formed by the interface 4b on the left side of the light absorbing portion 4 among the interfaces of the light transmissive portion 3 and the light absorbing portion 4 in the same posture, and the normal of the plane of the optical functional layer 2.

[0053] The angle θ 11 and the angle θ 12 (that is, 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. When θ 11 and θ 12 are within 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 vehicle). On the other hand, the angle θ 11 and the angle θ 12 are, for example, 6.5° or less, and preferably 5.5° or less. That is, the angle θ 11 and the angle θ 12 are, 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 incident side aperture ratio is, for example, 40% or less, preferably 35% or less. When the light incident side aperture ratio is within the above range, it becomes easier 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 the vehicle). On the other hand, the light incident side aperture ratio is, for example, 25% or more, preferably 30% or more. When the light incident side aperture ratio is within the above range, it is possible to suppress a decrease in the luminance of the display device. That is, the light incident side aperture ratio is, for example, preferably 25% or more and 40% or less, more preferably 30% or more and 35% or less. As shown in FIG. 4, the above light incident side aperture ratio is the ratio (Wa / Pa) of the width Wa of the light transmission portion 3 existing between the light absorption portions 4 to the distance Pa between the centers of the adjacent light absorption portions 4 on the surface opposite to the substrate layer 1 side.

[0055] The height Da of the light absorption portion is not particularly limited, and is, for example, 110 μm or more, preferably 120 μm or more. When the height Da of the light absorption portion is within the above range, it becomes easier 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 the vehicle). On the other hand, the height Da of the light absorption 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 absorption portion is not particularly limited, and is, for example, 3.5 or more, preferably 4.0 or more. On the other hand, the OD value of the light absorption portion is, for example, 5.0 or less, preferably 4.5 or less. Specifically, the OD value of the light absorption portion is, for example, preferably 3.5 or more and 5.0 or less, more preferably 4.0 or more and 4.5 or less.

[0057] The method for measuring the OD value of the above light absorption portion is as follows. First, the composition constituting the light absorption portion is applied on an easily adherent PET film with a thickness of 60 μm, laminated with an untreated PET film, and one side thereof is UV-cured. Then, UV curing is also performed from the other side to produce a measurement sample. The transmittance of this light absorption layer is measured with a transmittance densitometer, and the OD value is calculated.

[0058] In FIGS. 1 to 4, an example is shown in which the interface between the light transmission portion 3 and the light absorption portion 4 is linear in cross section. However, the present invention is not limited to this, and the interface may be a polygonal line, a convex curved surface, a concave curved surface, or the like. Further, in the plurality of light transmission portions 3 and light absorption portions 4, the cross-sectional shapes may be the same, or may have different cross-sectional shapes with a predetermined regularity.

[0059] 2. Substrate layer The substrate layer in the present embodiment is a flat sheet-like member that supports the optical functional layer. As the substrate layer, a resin substrate is used. As the material of the substrate layer, various materials can be used. 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 can be obtained at low cost 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 will be described later, when the optical sheet of the present embodiment is used in a liquid crystal display device, it is preferable that the birefringence (retardation) of the substrate layer is small in consideration of the combination of the surface light source device and the lower polarizing plate. As materials with small birefringence, TAC, methacrylic resin, and polycarbonate are preferably used. Further, in applications that require 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., which is suitable for in-vehicle applications that generally require 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 substrate layer is large. As a material with large birefringence, polyester is preferably used. Polyester is also advantageous in terms of cost and mechanical strength.

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

[0063] The retardation Re of the base material layer is represented by the following formula based on the refractive index nx in the direction with the largest refractive index (slow axis direction) in the plane of the base material layer, the refractive index ny in the direction orthogonal to the slow axis direction (fast axis direction), and the thickness d of the base material layer. Re = (nx - ny) × d

[0064] The above retardation is measured using a retardation measuring device. As the retardation measuring device, for example, the retardation measuring device "KOBRA-WR" manufactured by Oji Scientific Instruments Co., Ltd. is used. The measurement angle is 0° and the measurement wavelength is 589.3 nm.

[0065] The above nx - ny (hereinafter referred to as Δn) is preferably 0.05 or more. If the above Δn is too small, the thickness required to obtain the above retardation may become thick. On the other hand, the above Δn is preferably 0.25 or less. If the above Δn is too large, it is necessary to stretch the base material layer excessively, so the base material layer is likely to tear, break, etc., and the practicality as an industrial material may be significantly reduced. Therefore, the above Δn is more preferably 0.07 or more and 0.15 or less. In addition, if the above Δn exceeds 0.15, the durability of the base material layer in the damp heat resistance test may be inferior. Since the durability in the damp heat resistance test is excellent, the above Δn is even more preferably 0.12 or less.

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

[0067] The polyester is not particularly limited as long as it satisfies the above retardation. For example, linear saturated polyesters synthesized from aromatic dibasic acids or their ester-forming derivatives and diols or their ester-forming derivatives can be mentioned. Specifically, polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly(1,4-cyclohexylene dimethylene terephthalate), polyethylene-2,6-naphthalate can be mentioned. Further, the polyester may be a copolymer of these polyesters. Also, a mixture of polyester as a main component and other types of resins may 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 preferable from the viewpoint of good balance of mechanical properties, optical properties, etc. In particular, polyethylene terephthalate (PET) is preferable. This is because PET has high versatility and is easily available. Furthermore, PET is excellent in transparency, thermal or mechanical properties, the retardation can be controlled by stretching, the intrinsic birefringence is large, and a relatively large retardation can be obtained relatively easily even with a thin thickness.

[0068] When the base material layer is a polyester base material, the method for producing the polyester base material is not particularly limited as long as it satisfies the above retardation. For example, a method in which polyester is melted, an unstretched polyester extruded into a sheet shape is laterally stretched using a tenter or the like at a temperature equal to or higher than the glass transition temperature, and then heat-treated can be mentioned. The lateral stretching temperature is preferably 80°C or higher and 130°C or lower, and more preferably 90°C or higher and 120°C or lower. Also, the lateral stretching ratio is preferably 2.5 times or more and 6.0 times or less, and more preferably 3.0 times or more and 5.5 times or less. If the lateral stretching ratio is too large, the transparency of the obtained polyester base material may easily decrease. Also, if the lateral stretching ratio is too small, the stretching tension will also be small, so the birefringence of the obtained polyester base material will be small, and it may not satisfy the above retardation. Further, in the method for producing the polyester base material, after laterally stretching the above unstretched polyester under the above conditions using a biaxial stretching test apparatus, it may be stretched in the flow direction with respect to the lateral 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 above Δn may not satisfy the above-described preferred range. Also, the heat treatment temperature is preferably 100°C or higher and 250°C or lower, and is 180°C or higher and 245°C or lower.

[0069] As a method for controlling the retardation of the polyester base material produced by the above-described method within the above range, a method of appropriately setting the stretching ratio, stretching temperature, and thickness of the polyester base material to be produced can be mentioned. 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 base material 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 base material is too thin, the retardation of the polyester base material may not satisfy the above range. Further, if the thickness of the polyester base material is too thin, the anisotropy of mechanical properties becomes remarkable, and tearing, breaking, etc. are likely to occur, and the practicality as an industrial material may be significantly reduced. On the other hand, if the thickness of the polyester base material is too thick, the polyester base material is very rigid, the flexibility peculiar to the polymer film is reduced, and the practicality as an industrial material may also be reduced.

[0071] The total light transmittance of the base material layer is preferably 80% or more, 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 the present embodiment may have other layers other than the above base material layer and the above optical functional layer. Examples of the other layer include a hard coat layer having a rough surface. Such a hard coat layer having a rough surface is, for example, a hard coating layer whose surface exhibits a rough surface with an arithmetic mean roughness Ra of 0.1 μm or more according to JIS B0601:1994. In the present 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 hard coat layer can be made difficult to be damaged by contact with other adjacent optical members when the optical sheet is incorporated into the display device due to the rough surface of its surface. Further, the hard coat layer can suppress optical adhesion by the rough surface of its surface, and thus suppress the generation of interference fringes due to optical adhesion and make it difficult to reduce the optical performance. The hard coat layer having a rough surface may be disposed on the surface on the opposite side (light-emitting side) of the optical functional layer side of the base material layer, or may be disposed on the surface on the opposite side (light-incident side) of the base material layer side of the optical functional layer.

[0073] 4. Manufacturing Method The optical sheet in this embodiment can be manufactured, for example, as follows. First, a light-transmitting portion is formed on the base material layer. For this, a base material sheet serving as the base material layer is inserted between a mold roll having a shape on its surface capable of transferring the shape of the light-transmitting portion and a nip roll arranged to face the mold roll. At this time, while supplying a composition constituting the light-transmitting portion between the base material sheet and the mold roll, the mold roll and the nip roll are rotated. As a result, the groove corresponding to the light-transmitting portion formed on the surface of the mold roll (a shape obtained by inverting the shape of the light-transmitting portion) is filled with the composition constituting the light-transmitting portion, 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 acrylate-based, urethane acrylate-based, polyether acrylate-based, polyester acrylate-based, and polythiol-based resins.

[0075] Light for curing is irradiated from the base material sheet side by a light irradiation device onto the composition constituting the light-transmitting portion sandwiched between the mold roll and the base material sheet and filled therein. Thereby, the composition can be cured and its shape can be fixed. Then, the base material layer and the formed light-transmitting portion are released from the mold roll by a release roll.

[0076] Next, a light-absorbing portion is formed. To form the light-absorbing portion, first, a composition constituting the light-absorbing portion is filled in the space between the above light-transmitting portions. Then, the excess composition is scraped off with a doctor blade or the like. And the remaining composition is cured from the light-transmitting portion side, and the light-absorbing portion can be formed. Examples of the curing method include curing by ultraviolet irradiation and curing by heating.

[0077] The composition constituting the light absorption part is not particularly limited. For example, a composition in which colored light absorption particles are dispersed in a photocurable resin such as urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, and butadiene (meth) acrylate can be mentioned. In addition, a composition in which colored light absorption particles are dispersed in a thermosetting resin can also be used.

[0078] Alternatively, instead of dispersing the light absorption particles, the entire light absorption part can be colored with a pigment or a dye. As the light absorption particles, light-absorbing colored particles such as carbon black are preferably used. The light absorption particles are not limited to these, and colored particles that selectively absorb a specific wavelength according to the characteristics of the video 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, the colored organic fine particles are preferably used from the viewpoints of cost, quality, and ease of availability. 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" means the diameter obtained by observing 100 light absorption particles with an electron microscope, measuring their diameters, and calculating the arithmetic mean.

[0079] 5. Optical Sheet The optical sheet in the present embodiment has a rectangular shape having a pair of first sides L1 extending in the first direction and a pair of second sides L2 extending in the 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 the present embodiment is not particularly limited, and for example, it is used in a display device. Among them, the optical sheet of the present 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 a vehicle. The optical sheet may be disposed on the observer side of the display panel in the display device, or may be included in the surface light source device in the display device.

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

[0082] The 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 in the present embodiment. Further, FIG. 6 shows a part of an exploded cross-sectional view of the display device cut along the line II-II shown in FIG. 5, and FIG. 7 shows a part of an exploded cross-sectional view of the display device cut along the line III-III shown in FIG. 5. The display device shown in FIGS. 5 to 7 is an example of a liquid crystal display device.

[0083] As shown in FIGS. 5 to 7, the display device 50A including the surface light source device 20 in the present embodiment includes a liquid crystal panel 15, a surface light source device 20, and a functional film 40. FIGS. 5 to 7 also show the orientation in the posture in which the display device is installed, but the installation posture is not limited thereto. For example, as shown in FIG. 5, the display device is preferably arranged in a posture such that the first direction D1 in FIGS. 1 to 4 is the horizontal direction and the second direction D2 is the vertical direction, but is not limited to this posture. Hereinafter, each member will be described.

[0084] The surface light source device 20 in FIGS. 5 to 7 has the above-described optical sheet 10A, is disposed on the side opposite to the observer side from the liquid crystal panel 15, and is an illumination device that emits planar light to the liquid crystal panel 15. Further, the surface light source device 20 in FIGS. 5 to 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 reflective sheet 29. As shown in FIGS. 5 to 7, in the surface light source device 20, the optical sheet 10A is disposed such that the base material layer 1 is on the observer side with respect to the optical functional layer 2.

[0085] As shown in FIGS. 5 to 7, the light guide plate 21 has a base portion 22 and a back surface optical element 23. The light guide plate 21 is a plate-shaped member as a whole formed of a light-transmissive material. As shown in FIGS. 5 to 7, one plate surface side on the observer side of the light guide plate 21 is a smooth surface, and the other plate surface side, which is the opposite side, is a back surface, and a plurality of back surface optical elements 23 are arranged on the back surface.

[0086] As the materials for the base portion 22 and the back surface optical element 23, various materials can be used. 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 available at low cost 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, polyethersulfones, and reactive resins such as epoxy acrylates and urethane acrylates (ionizing radiation curable resins, etc.).

[0087] The base portion 22 is a plate shape having a predetermined thickness at a portion that guides light inside and serves as a base for the back surface optical element 23.

[0088] The back optical element 23 is a protruding element formed on the back side of the base 22, and is triangular prism-shaped in FIGS. 5 to 7. The back optical element 23 is columnar with the ridge line of the protruding top extending in the horizontal direction, and a plurality of back optical elements 23 are arranged at a predetermined pitch in a direction (vertical direction) orthogonal to the extending direction. The back optical elements 23 in FIGS. 5 to 7 have a triangular cross section, but are not limited thereto, and may have any cross-sectional shape such as polygonal, hemispherical, a part of a sphere, or a lens shape.

[0089] It is preferable that the arrangement direction of the plurality of back optical elements 23 is the light guiding direction. That is, they are arranged in a direction away from the light source 25, and the ridge lines of the respective back optical elements 23 extend parallel to the direction in which the light source 25 is arranged, or in the case of a single long light source, in the direction in which the light source extends.

[0090] Note that the "triangular shape" in this specification includes not only a strictly triangular shape but also a substantially triangular shape including limitations in manufacturing technology and errors during molding. Similarly, terms used in this specification to specify other shapes and geometric conditions, such as terms like "parallel", "orthogonal", "ellipse", "circle", etc., are also to be interpreted including errors to the extent that similar optical functions can be expected without being bound by a strict meaning.

[0091] The light guide plate 21 having such a configuration can be manufactured by extrusion molding or by shaping the back optical element 23 on the base 22. In the light guide plate 21 manufactured by extrusion molding, the base 22 and the back optical element 23 can be integrally formed. Also, when manufacturing the light guide plate 21 by shaping, the back optical element 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 side surface (end surface) of the side surfaces (end surfaces) of the base portion 22 of the light guide plate 21 in the direction in which the back surface optical element 23 is arranged. The light source is not particularly limited and can be configured in various forms such as a fluorescent lamp like a linear cold cathode tube, a dot-like LED (light emitting diode), or an incandescent bulb. In FIGS. 5 to 7, the light source 25 is composed of a plurality of LEDs and is configured such that the lighting and extinguishing of each LED and / or the brightness at the time of lighting of each LED can be individually and independently adjusted by a control device (not shown).

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

[0094] Next, the light diffusing plate 26 will be described. The light diffusing plate 26 is a member that is disposed on the light emitting side of the light guide plate 21 and has a function of diffusing the light incident thereon and then emitting it. Thereby, the uniformity of the light emitted from the light guide plate 21 can be further enhanced, and the scratches existing on the light guide plate 21 can be made less noticeable. As a specific form of the light diffusing plate, a known light diffusing plate can be used, and for example, a form in which a light diffusing agent is dispersed in a base material can be cited. The light diffusing plate 26 can be used as a support plate for the prism layer 27 as shown in FIGS. 5 to 7. Further, when the light emitting surface of the light guide plate 21 is smooth, the light diffusing plate 26 may be bonded to the light guide plate 21 to form an integral body.

[0095] As can be seen from FIGS. 5 to 7, the prism layer 27 is a layer provided on the side closer to the liquid crystal panel 15 than the light diffusing plate 26 and includes unit prisms 27a that are convex toward the liquid crystal panel 15 side. In FIGS. 5 to 7, the unit prism 27a has a form in which it has a predetermined cross section and extends in the light guiding direction (the vertical direction in this embodiment) of the light guide plate 21. And a plurality of unit prisms 27a are arranged in a direction different from the light guiding direction (the horizontal direction, which is a direction orthogonal to the light guiding direction in plan view in this embodiment).

[0096] The cross-sectional shape of the unit prism of such a prism layer can be a known shape according to the required function. With such a shape, light can be further diffused or condensed.

[0097] Also, the direction in which the unit prism extends and the direction in which it is arranged are not limited to the above form, and other forms may be used. For example, a form in which the unit prism has a predetermined cross-section and extends in a direction orthogonal to the light guiding direction of the light guide plate 21, and a plurality of unit prisms are arranged in the light guiding direction may be used.

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

[0099] The reflection sheet 29 of the surface light source device 20 will be described. The reflection sheet 29 is a member for reflecting the light emitted from the back surface of the light guide plate 21 and making the light incident on the light guide plate 21 again. As the reflection sheet 29, a sheet made of a material having a high reflectivity such as metal, or a sheet including a thin film made of a material having a high reflectivity (for example, a metal thin film) as a surface layer, which enables so-called specular reflection, can be preferably applied.

[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 an image composed of, for example, a moving image, a still image, character information, or a combination thereof 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 arranged in front of the passenger seat of a vehicle, it is possible to control the emission of image light to the driver's side and to control the reflection of image light on the front glass in front of the passenger seat.

[0101] The display device in 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-described optical sheet. Further, in the display device of this embodiment, the above-described optical sheet may be disposed on the observer side of the display panel.

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

[0103] FIGS. 5 to 7 are schematic plan views and cross-sectional views showing an example of the display device of this embodiment. Since FIGS. 5 to 7 are described in the section of the above "B-1. Surface light source device (first embodiment)", the description here is omitted.

[0104] 1. Surface light source device Since the surface light source device is described in the section of the above "B-1. Surface light source device (first embodiment)", the description here is omitted.

[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 disposed on the observer side, a lower polarizing plate 14 disposed on the surface light source device 20 side, and a liquid crystal layer 12 disposed between the upper polarizing plate 13 and the lower polarizing plate 14. The upper polarizing plate 13 and the lower polarizing plate 14 decompose the incident light into two orthogonal polarization components (P wave and S wave), transmit the polarization component in one direction (the direction parallel to the transmission axis) (for example, P wave), and absorb the polarization component in the other direction (the direction parallel to the absorption axis) orthogonal to the one direction (for example, S wave).

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

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

[0108] There are several types of liquid crystal panels, but the types are not particularly limited, and known types of liquid crystal panels can be used. Specifically, TN, STN, VA, MVA, IPS, OCB, etc. can be mentioned.

[0109] 3. Other members As shown in FIGS. 5 to 7, the display device of the present embodiment may have a functional film 40 disposed on the light exit side of the liquid crystal panel 15. The functional film 40 is a member having a function of improving the quality of image light or 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, a light diffusion film, etc., and these are configured alone or in combination of a plurality.

[0110] 4. Operation Next, the operation of the display device 50A having the above configuration will be described while showing an optical path example. However, the optical path example is a conceptual one for explanation and does not strictly represent the degree of reflection or refraction.

[0111] First, as shown in FIG. 7, the light emitted from the light source 25 enters the light guide plate 21 from the light incident surface which is the side surface (end surface) of the light guide plate 21. In FIG. 7, as an example, the optical path examples of the light L21 and L22 incident from the light source 25 to the light guide plate 21 are shown.

[0112] As shown in FIG. 7, the light L21 and L22 incident on the light guide plate 21 are repeatedly totally reflected due to the refractive index difference with air on the light emitting side surface of the light guide plate 21 and the back surface on the opposite side thereof, and proceed in the light guiding direction (the direction below the paper surface of FIG. 7).

[0113] However, the back surface optical element 23 is disposed on the back surface of the light guide plate 21. Therefore, as shown in FIG. 7, the light L21 and L22 traveling in the light guide plate 21 change their traveling directions by the back surface optical element 23, and may enter the light emitting surface and the back surface at an incident angle less than the total reflection critical angle. In this case, the light can be emitted from the light emitting surface of the light guide plate 21 and the back surface on the opposite side thereof.

[0114] The light L21 and L22 emitted from the light emitting surface head toward the light diffusion plate 26 disposed on the light emitting 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 disposed on the back surface of the light guide plate 21, enters the light guide plate 21 again, and travels in the light guide plate 21.

[0115] The light traveling in the light guide plate 21 and the light that changes its direction by the back surface optical element 23 and reaches the light emitting surface at an incident angle less than the total reflection critical angle occur in each region along the light guiding direction in the light guide plate 21. Therefore, the light traveling in the light guide plate 21 gradually comes to be emitted from the light emitting surface. Thereby, the light quantity distribution along the light guiding direction of the light emitted from the light emitting surface of the light guide plate 21 can be made uniform.

[0116] The light emitted from the light guide plate 21 then reaches the light diffusion plate 26, and the uniformity is enhanced. Then, it is diffused or condensed as necessary by the prism layer 27, and the light emitted from the prism layer 27 reaches the reflective polarizing plate 28. Here, the light in the polarization direction along the transmission axis of the reflective polarizing plate 28 passes through the reflective polarizing plate 28 and heads toward the optical sheet 10A.

[0117] On the other hand, the light with the polarization direction along the reflection axis of the reflective polarizing plate 28 is reflected as shown by the dotted arrow in FIG. 7 and returned to the light guide plate 21 side. The returned light is reflected by the light guide plate 21, the back surface optical element 23, or the reflection sheet 29 and travels again toward the reflective polarizing plate 28 side. During this reflection, the polarization direction of a part of the light changes, and a part of it passes through the reflective polarizing plate 28. The other light is returned to the light guide plate side again. In this way, the light reflected by the reflective polarizing plate 28 can also pass through the reflective polarizing plate 28 by repeating the reflection. As a result, the utilization rate of the light from the light source 25 is increased. Here, the light emitted from the reflective polarizing plate 28 has a polarization direction along the transmission axis of the lower polarizing plate 14 and becomes polarized light that passes through the lower polarizing plate 14.

[0118] The light emitted from the reflective polarizing plate 28 reaches the optical sheet 10A. The light incident on the optical sheet 10A 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 polarization component of the incident light and absorbs the other polarization component. The light transmitted through the lower polarizing plate 14 selectively passes through the upper polarizing plate 13 according to 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, enabling an observer of the liquid crystal display device to observe an image. At that time, the image light is provided to the observer through the functional film 40, and the quality of the image is improved.

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

[0121] The display device in the present embodiment is preferably used, for example, as an in-vehicle display device, and particularly preferably 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 in the present embodiment, the base material layer 1 in the optical sheet 10A is arranged on the observer side with respect to the optical function layer 2. FIG. 8(a) is a schematic view of the front inside of a vehicle in which the display device 50A in the present embodiment is arranged 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 first direction D1 in the optical sheet is in the horizontal direction (left - right direction of the vehicle), the second direction D2 is in the vertical direction, and the third direction D3 is in the horizontal direction (front - rear direction of the vehicle). On the other hand, the installation posture of the display device is not limited to this.

[0123] When the display device in the present embodiment is used as a display device for the passenger seat arranged in front of the passenger seat of the vehicle, it is possible to control the emission of video light to the driver side. Also, it is possible to control the reflection of video light on the windshield in front of the passenger seat, and it is possible to suppress the driver from visually recognizing the reflection on the windshield.

[0124] In addition, the display device in the present embodiment can be used as a display device for the rear seat arranged on the ceiling or headrest of the vehicle. When display devices for the rear seats are installed in the rear seats respectively, it is possible to suppress the emission of video light in the left - right direction and suppress the reduction of visibility due to the reflection of the video light of the display device for the adjacent rear seat into the display device for the observer's rear seat. In particular, when the observer is observing a low - brightness image on the display device for the rear seat and a high - brightness image is being displayed on the adjacent display device for the rear seat, the reduction of visibility can be further suppressed. Also, it is possible to suppress the emission of video light in the upward direction, and in particular, control the reflection of video light on the ceiling of the rear seat at night, and suppress the driver from visually recognizing the reflection on the ceiling.

[0125] In addition, the display device in the present embodiment can be used for display devices arranged in seats of buses, trains, airplanes, etc. In this case, the emission of video light in the left-right direction can be suppressed, and privacy can be protected. In addition, the emission of video light in the upward direction can be suppressed, and in particular, the reflection of video light on the ceiling of the seat at night can be controlled, and it is possible to suppress others than the observer from visually recognizing the reflection on the ceiling.

[0126] The display device in the present embodiment can also be used for various applications such as advertising, presentations, television images, and display of various information indoors or outdoors.

[0127] C-1-2. Display Device (Second Example of the First Embodiment) The display device in the present embodiment includes a display panel and the optical sheet of the above-described first embodiment disposed on the observer side of the display panel.

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

[0129] 1. Optical Sheet Since the optical sheet is described in the section of "A-1. Optical Sheet (First Embodiment)", the description here is omitted.

[0130] 2. Display Panel Examples of the display panel include, for example, a liquid crystal panel and an organic electroluminescence panel. The liquid crystal panel shall be the same as the liquid crystal panel described in the section of "C-1-1. Display device (the first example of the first embodiment)". As for the organic electroluminescence panel, a known organic electroluminescence panel can be used.

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

[0132] When the display panel is a liquid crystal panel, the display device of this embodiment usually has a surface light source device on the surface opposite to the optical sheet side of the liquid crystal panel. As for the surface light source device, a known surface light source device can be used.

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

[0134] 4. Applications Since the applications of the display device in this embodiment are the same as those described in the section of "C-1-1. Display device (the first example of the first embodiment)", the description here is omitted.

[0135] A-2. Optical sheet (the second embodiment) As shown in FIGS. 1 to 4, for example, the optical sheet 10B of 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 optical sheet 10B of this embodiment has a rectangular shape having a pair of first sides L1 extending in the first direction and a pair of second sides L2 extending in the second direction in a plan view. The optical functional layer 2 has a plurality of light transmission portions 3 having a predetermined cross section and extending in one direction, and light absorption portions 4 formed between adjacent light transmission portions 3. A predetermined cross section of the light transmission portion 3 is trapezoidal, and the short upper base is on 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 extending direction of the light transmission portion 3 has an angle of 1.5° or more and 20° or less with respect to the second direction D2.

[0136] Details of FIGS. 1 to 4 are described in the section of the above "A-1. Optical Sheet (First Embodiment)", and thus the description here is omitted.

[0137] The optical sheet in this embodiment includes an optical functional layer having a light transmission portion and a light absorption portion that extend in a predetermined direction and have a predetermined cross section, thereby reducing the transmittance of light in a direction inclined by ±30° toward the first direction with respect to the third direction. Specifically, when the light transmittance in the third direction is 100%, the relative transmittance, which is the ratio of the light transmittance in the direction inclined by ±30° toward the first direction with respect to the third direction, can be 1% or less.

[0138] Furthermore, in a state where the light emission angle in the first direction D1 is controlled, since the extending direction of the light transmission portion 3 has an angle θ of 1.5° or more and 20° or less with respect to the second direction, it is possible to control the light emission angle in the second direction D2.

[0139] Therefore, when the optical sheet of this embodiment is used for a display device, the light emission angles of the display device in the left-right direction and the up-down direction can be controlled. More specifically, when used as an optical sheet for a display device disposed in front of the passenger seat of a vehicle, it is possible to control the emission of video light toward the driver side, and it is also possible to control the reflection of video light on the front glass in front of the passenger seat.

[0140] The optical sheet in the present 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 the present embodiment are the same as those of the above-described "A-1. Optical Sheet (First Embodiment)", and thus the description thereof is omitted here.

[0142] B-2. Surface Light Source Device (Second Embodiment) The surface light source device 20 of the present embodiment includes, for example, as shown in FIGS. 5 to 7, the above-described optical sheet 10B of the second embodiment 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 for a display device for the passenger seat.

[0143] Details of FIGS. 5 to 7 are described in the section of the above "B-1. Surface Light Source Device (First Embodiment)", and thus the description thereof is omitted here.

[0144] Regarding other members of the light source and the surface light source device, they are described in the section of the above "B-1. Surface Light Source Device (First Embodiment)", and thus the description thereof is omitted here.

[0145] C-2. Display Device (Second Embodiment) The display device in the present embodiment includes the above-described optical sheet of the second embodiment and a display panel. According to the display device of the present embodiment, when used as a display device disposed in front of the passenger seat of a vehicle, it is possible to control the emission of video light to the driver side, and it is also possible to control the reflection of video light on the windshield in front of the passenger seat.

[0146] The display device in the present embodiment further has two embodiments. The display device of the present embodiment includes a surface light source device, and the surface light source device may include the above-described optical sheet. Also, in the display device of the present embodiment, the above-described optical sheet may be disposed on the observer side of the display panel.

[0147] C-2-1. Display Device (First Example of the Second Embodiment) The display device in the present embodiment includes a surface light source device including the above-described optical sheet, and a display panel laminated on the surface light source device.

[0148] Figs. 5 to 7 are schematic plan views and cross-sectional views showing an example of the display device of the present embodiment. Since Figs. 5 to 7 are described in the section of "B-1. Surface light source device (first embodiment)", the description here is omitted. As shown in Figs. 5 to 7, in the display device 50B in the present embodiment, the base material layer 1 in the optical sheet 10B is arranged so as to be on the observer (passenger seat) side with respect to the optical functional layer 2.

[0149] 1. Surface light source device Since the surface light source device is described in the section of "B-2. Surface light source device (second embodiment)", the description here is omitted.

[0150] 2. Display panel and other members Since the display panel and other members are described in the section of "C-1-1. Display device (first example of the first embodiment)", the description here is omitted.

[0151] 3. Applications The display device in the present embodiment is used as a display device arranged in front of the passenger seat of a vehicle. Fig. 8(a) is a schematic view of the front inside of a vehicle in which the display device 50B in the present embodiment is arranged in front of the passenger seat. 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 Figs. 8(a) and 8(b), the first direction D1 in the optical sheet is arranged to be the horizontal direction (left-right direction of the vehicle), the second direction D2 is arranged to be the vertical direction, and the third direction D3 is arranged to be the horizontal direction (front-rear direction of the vehicle). On the other hand, 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 the present embodiment includes a display panel and the optical sheet of the above-described second embodiment arranged on the observer side of the display panel.

[0153] FIG. 9 is an exploded cross-sectional view illustrating the display device 50F in the present embodiment. Since FIG. 9 has been described in the section of "C-1-2. Display device (second example of the first embodiment)", the description thereof will be omitted here. As shown in FIG. 9, in the display device 50F in the present embodiment, the base material layer 1 in the optical sheet 10B is arranged so as to be on the observer (passenger seat) side with respect to the optical functional layer 2.

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

[0155] 2. Display panel and other members Since the display panel and other members have been described in the section of "C-1-2. Display device (second example of the first embodiment)", the description thereof will be omitted here.

[0156] 4. Use The display device in the present embodiment is used as a display device arranged in front of the passenger seat of a vehicle. Since the use of the display device in the present embodiment is the same as the use described in the section of "C-1-2. Display device (second example of the first embodiment)", the description thereof will be omitted here.

[0157] C-3. Display device (third embodiment) The display device of the present embodiment is a display device including an optical sheet and a display panel. The optical sheet includes a base material layer and an optical functional layer laminated on one surface of the base material layer. The optical functional layer has a plurality of light transmission portions having a predetermined cross-section and extending in one direction, and a light absorption portion formed between adjacent light transmission portions. The predetermined cross-section of the light transmission portion is trapezoidal, with the short upper base on the light incident side. When the display device is installed, the optical sheet has a relative transmittance, which is the ratio of the light transmittance in the direction inclined by ±30° from the normal direction to the left and right directions to the light transmittance in the normal direction of the main surface of the optical sheet being 100%, of 1% or less. The extending direction of the light transmission 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.

[0158] The display device in 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-described optical sheet. Further, in the display device of this embodiment, the above-described optical sheet may be disposed on the observer side of the display panel.

[0159] C-3-1. Display Device (First Example of the Third Embodiment) Figs. 5 to 7 are schematic plan views and cross-sectional views showing an example of the display device of this embodiment. Further, 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. The display device 50C of this embodiment includes, as shown in Figs. 5 to 7, 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. The optical sheet 10C in this embodiment includes, as shown in Figs. 1 to 4, a base material layer 1 and an optical functional layer 2 laminated on one surface of the base material layer 1. The optical functional layer 2 has a plurality of light transmission portions 3 having a predetermined cross-section and extending in one direction, and light absorption portions 4 formed between adjacent light transmission portions 3. A predetermined cross-section of the light transmission portion 3 is trapezoidal, and the short upper base is the light incident side. As shown in Fig. 2, when the transmittance of light in the normal direction N (the third direction D3 in Figs. 1 to 4) of the main surface S of the optical sheet is set to 100% when the display device 50C is installed, the optical sheet 10C has a relative transmittance, which is the ratio of the transmittance of light in a direction inclined by ±30° in the left-right direction from the normal direction N, of 1% or less. Further, as shown in Fig. 3, when the display device 50C is installed, the extending direction of the light transmission portion 3 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] Details of Figs. 1 to 4 are described in the section of the above "A-1. Optical Sheet (First Embodiment)", so the description here is omitted. Further, since Figs. 5 to 7 are described in the section of the above "B-1. Surface Light Source Device (First Embodiment)", the description here is omitted.

[0161] The display device 50C of the present embodiment has a predetermined optical sheet 10C. Since the relative transmittance, which is the ratio of the light transmittance in the direction inclined by ±30° in the left-right direction with respect to the normal direction, is equal to or less than a predetermined value when the display device is installed, the optical sheet 10C in the present embodiment can control the light emission angle of the display device in the left-right direction. Further, in a state where the light emission angle in the left-right direction is controlled, the extending direction of the light transmission portion viewed from the normal direction has an angle θ within a predetermined range with respect to the vertical direction, so that the light emission angle of the display device in the up-down direction can be controlled.

[0162] Therefore, it becomes a display device capable of controlling the light emission angles in the left-right direction and the up-down direction. More specifically, when it is arranged in front of the passenger seat of a vehicle, it is possible to control the emission of video light toward the driver side, and it is also possible to control the reflection of video light on the front glass 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, the optical sheet 10C in the present embodiment has a relative transmittance, which is the ratio of the light transmittance in the direction inclined by ±30° in the left-right direction from the normal direction N (the third direction D3 in FIGS. 1 to 4) of the main surface of the optical sheet, equal to or less than 1% when the light transmittance in the normal direction of the optical sheet is 100%. The relative transmittance of the above light is preferably equal to or less than 0.6%, and more preferably equal to or less than 0.4%.

[0164] In the optical sheet of the present embodiment, when the light transmittance in the normal direction is 100%, the relative transmittance, which is the ratio of the light transmittance in the direction inclined by ±20° in the left-right direction with respect to the normal direction, is preferably equal to or less than 10%, and more preferably equal to or less than 5%.

[0165] Furthermore, when the display device is installed, the optical sheet in this embodiment has an extending direction of the light transmissive portion, as viewed from the normal direction, at an angle of 1.5° or more and 20° or less with respect to the vertical direction. The above angle θ is 1.5° or more, and may be 5° or more, or may be 10° or more. On the other hand, the above angle θ is 20° or less, and may be 15° or less. When the above angle θ is within the above range, it becomes possible to control the light emission angle in the left-right direction. In FIGS. 1 and 3, the light transmissive portion 3 has an angle θ to 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 transmissive portion 3 may have an angle θ to 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 above angle θ is obtained by the following method. First, as illustrated in FIGS. 8(a) and 8(b), assume a state where the display device 50 is installed. At this time, the optical sheet of the display device 50 may be vertically long 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 the observer (e.g., the passenger seat) views the display device 50 from the front, measure the smaller of the angles formed by the vertical line (the line in the direction of gravity) and the boundary line BL between the light transmissive portion 3 and the light absorption portion 4. When measuring the above angle, use the boundary line BL between the light transmissive portion 3 and the light absorption portion 4 on the surface of the short upper base of the light transmissive portion 3 and the long lower base of the light absorption portion 4 of the optical function layer 2. Also, as illustrated in FIG. 8(b), measure the above angle at two locations on each of the left and right sides of the display device 50, and use the arithmetic mean value of the four measurement values as the above angle θ. The above two locations are the locations that are 1 / 3 of the vertical length K of the display device 50 from the upper side of the display device 50 and the locations that are 1 / 3 of the vertical length K of the display device 50 from the lower side of the display device 50.

[0167] In this embodiment, the features of the optical sheet having the above optical characteristics and other features are the same as those of the above-described "A-1. Optical Sheet (First Embodiment)", so the description here is omitted. As for the other members of the surface light source device, since they are described in the section of the above "B-1. Surface Light Source Device (First Embodiment)", the description here is omitted.

[0168] 2. Display Panel and Other Members The display panel and other members are described in the section of the above "C-1-1. Display Device (First Example of the First Embodiment)", so the description here is omitted.

[0169] 3. Applications The applications of the display device in this embodiment are the same as those of the above-described "C-1-1. Display Device (First Example of the First Embodiment)", so the description here is omitted.

[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 the present embodiment. FIGS. 1 to 4 are a schematic perspective view, a cross-sectional view, and a plan view showing an example of an optical sheet in the display device of the present embodiment. As shown in FIG. 9, the display device 50G of the present embodiment includes a display panel 30 and an optical sheet 10C disposed on the observer side of the display panel 30. As shown in FIGS. 1 to 4, the optical sheet 10C in the present embodiment includes a base material layer 1 and an optical functional layer 2 laminated on one surface of the base material layer 1. The optical functional layer 2 has a plurality of light transmission portions 3 having a predetermined cross-section and extending in one direction, and a light absorption portion 4 formed between adjacent light transmission portions 3. A predetermined cross-section of the light transmission portion 3 is trapezoidal, and the short upper base is the light incident side. As shown in FIG. 2, when the display device 50G is installed, the optical sheet 10C has a relative transmittance that is a ratio of the light transmittance in a direction inclined by ±30° from the normal direction N (the third direction D3 in FIGS. 1 to 4) of the main surface S of the optical sheet to 1% or less when the light transmittance in the normal direction N is 100%. Further, as shown in FIG. 3, when the display device 50G is installed, the extending direction of the light transmission portion 3 viewed from the normal direction N of the optical sheet 10C has an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0171] Details of FIGS. 1 to 4 are described in the section of "A-1. Optical Sheet (First Embodiment)" above, so the description here is omitted. Further, since FIG. 9 is described in the section of "C-1-2. Display Device (Second Example of First Embodiment)" above, the description here is omitted.

[0172] 1. Optical Sheet The optical sheet is the same as the optical sheet described in the section of "C-3-1. Display Device (First Example of Third Embodiment)" above, so the description here is omitted.

[0173] 2. Display Panel and Other Members The display panel and other members are described in the section of "C-1-2. Display Device (Second Example of First Embodiment)" above, so the description here is omitted.

[0174] 3. Use Since the use of the display device in this embodiment is the same as that of the "C-1-1. Display device (the first example of the first embodiment)" described above, the description here is omitted.

[0175] C-4. Display device (the fourth embodiment) The display device of this embodiment includes an optical sheet and a display panel, and is a display device disposed in front of the passenger seat of a vehicle. The optical sheet includes a base material layer and an optical functional layer laminated on one surface of the base material layer. The optical functional layer has a plurality of light transmission portions that have a predetermined cross-section and extend in one direction, and light absorption portions formed between adjacent light transmission portions. The predetermined cross-section of the light transmission portion is trapezoidal, with the short upper base on the light incident side. When the display device is installed in front of the passenger seat of the vehicle, the extending direction of the light transmission portion 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 in 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-described optical sheet. Also, in the display device of this embodiment, the above-described optical sheet may be disposed on the observer side of the display panel.

[0177] C-4-1. Display device (the first example of the fourth embodiment) Figs. 5 to 7 are schematic plan views and cross-sectional views showing an example of the display device of the present embodiment. 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 the present embodiment. As shown in Figs. 5 to 7, the display device 50D in the present embodiment 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 a display device disposed in front of the passenger seat of the vehicle. As shown in Figs. 1 to 4, the optical sheet 10D in the present embodiment includes a base material layer 1 and an optical functional layer 2 laminated on one surface of the base material layer 1. The optical functional layer 2 has a plurality of light transmission portions 3 having a predetermined cross-section and extending in one direction, and a light absorption portion 4 formed between adjacent light transmission portions 3. A predetermined cross-section of the light transmission portion 3 is trapezoidal, and the short upper base is the light incident side. When the display device is installed in front of the passenger seat of the vehicle, the extending direction of the light transmission portion 3 viewed from the normal direction N (the third direction D3 in Figs. 1 to 4) of the main surface of the optical sheet 10D has an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0178] The display device 50D in the present embodiment has a predetermined optical sheet 10D. By including an optical functional layer having a light transmission portion and a light absorption portion that extend in a predetermined direction and have a predetermined cross-section, when the display device is installed in front of the passenger seat of the vehicle, the transmittance of light in a direction inclined by ±30° in the left-right direction with respect to the normal direction can be reduced. Specifically, when the transmittance of light in the normal direction is 100%, the relative transmittance, which is the ratio of the transmittance of light in a direction inclined by ±30° to the left and right with respect to the normal direction, can be made 1% or less. Therefore, it is possible to control the light emission angle in the left-right direction of the display device.

[0179] Furthermore, in a state where the light emission angle in the left - right direction is controlled, since the extending direction of the light transmission portion as viewed from the normal direction has an angle θ within a predetermined range with respect to the vertical direction, it becomes possible to control the light emission angle in the up - down direction of the display device. Therefore, the display device of the present embodiment can control the emission of video light toward the driver's side and can also control the reflection of video 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 the present embodiment includes an optical functional layer having a light transmission portion and a light absorption portion that extend in a predetermined direction and have a predetermined cross - section. Thereby, when the display device 50D having the predetermined optical sheet 10D is installed in front of the passenger seat of the vehicle, 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 the direction inclined by ± 30° from the normal direction N to the left - right direction, can be set to 1% or less. The relative transmittance of the above light is preferably 0.6% or less, and more preferably 0.4% or less.

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

[0182] Furthermore, when a display device is installed in front of the passenger seat of a vehicle, the optical sheet in the present embodiment has an extending direction of the light transmissive portion, as viewed from the normal direction, having 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 may be 10° or more. On the other hand, the angle θ is 20° or less, and may be 15° or less. By the angle θ being within the above range, control of the light emission angle in the left-right direction becomes possible. In FIGS. 1 and 3, the light transmissive portion 3 has an angle θ to 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 transmissive portion 3 may have an angle θ to 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 the present embodiment are the same as those of the "A-1. Optical Sheet (First Embodiment)" described above, and thus the description here is omitted. Other members of the surface light source device are described in the section of the above "B-1. Surface Light Source Device (First Embodiment)", and thus the description here is omitted.

[0184] 2. Display Panel and Other Members The display panel and other members are described in the section of the above "C-1-1. Display Device (First Example of the First Embodiment)", and thus the description here is omitted.

[0185] 3. Applications The display device in the present embodiment is arranged in front of the passenger seat of a vehicle. FIG. 8(a) is a schematic view of the front inside of a vehicle when the display device 50D in the present embodiment is arranged 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 left-right direction of the optical sheet is the horizontal direction (left-right direction of the vehicle), the up-down direction is the vertical direction, and the thickness direction is the horizontal direction (front-rear direction of the vehicle). On the other hand, 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 the present embodiment. 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 the present embodiment. As shown in FIG. 9, the display device 50H in the present embodiment includes a display panel 30 and an optical sheet 10D disposed on the observer side of the display panel 30, and is a display device disposed in front of the passenger seat of a vehicle. As shown in FIGS. 1 to 4, the optical sheet 10D in the present embodiment includes a base material layer 1 and an optical functional layer 2 laminated on one surface of the base material layer 1. The optical functional layer 2 has a plurality of light transmission portions 3 having a predetermined cross-section and extending in one direction, and a light absorption portion 4 formed between adjacent light transmission portions 3. A predetermined cross-section of the light transmission portion 3 is trapezoidal, and the short upper base is on the light incident side. When the display device is installed in front of the passenger seat of the vehicle, the optical sheet 10D has an extending direction of the light transmission portion 3 viewed from the normal direction N (the third direction D3 in FIGS. 1 to 4) of the main surface of the optical sheet 10D with an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0187] The display device 50D in the present embodiment has a predetermined optical sheet 10D. By including an optical functional layer having a light transmission portion and a light absorption portion that extend in a predetermined direction and have a predetermined cross-section, when the display device is installed in front of the passenger seat of the vehicle, the transmittance of light in a direction inclined by ±30° in the left-right direction with respect to the normal direction can be reduced. Specifically, when the transmittance of light in the normal direction is 100%, the relative transmittance, which is the ratio of the transmittance of light in a direction inclined by ±30° in the left-right direction with respect to the normal direction, can be made 1% or less. Therefore, it is possible to control the light emission angle in the left-right direction of the display device.

[0188] Furthermore, in a state where the light emission angle in the left-right direction is controlled, since the extending direction of the light transmission portion as viewed from the normal direction has an angle θ within a predetermined range with respect to the vertical direction, it becomes possible to control the light emission angle in the up-down direction of the display device. Therefore, the display device according to the present embodiment can control the emission of video light toward the driver side and can also control the reflection of video light on the windshield in front of the passenger seat.

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

[0190] 2. Display panel and other members Since the display panel and other members are described in the section of "C-1-1. Display device (first example of the first embodiment)", the description here is omitted.

[0191] 3. Applications The applications of the display device in the present embodiment are the same as those of "C-1-1. Display device (first example of the first embodiment)".

[0192] A-3. Optical sheet (fifth embodiment) FIG. 1 is a schematic perspective view showing an example of the optical sheet of the present embodiment. Further, FIG. 10 shows a cross-sectional view of the optical sheet cut along the line indicated by I-I in FIG. 1. FIG. 3 is a plan view of the optical sheet shown in FIG. 1 as viewed along the direction (-D3 direction) from the base material layer 1 toward 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 the present embodiment includes a base material layer 1 and an optical functional layer 2 laminated on one surface of the base material layer 1. The optical sheet 10E of the present embodiment has a rectangular shape 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 in a plan view. The optical functional layer 2 has a plurality of light transmission portions 3 having a predetermined cross-section and extending in one direction, and light absorption portions 4 formed between adjacent light transmission portions 3. As shown in FIG. 10, the cross-section of the light transmission portion 3 is trapezoidal, and the short upper base is the light incident side (light source side). In the present 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 the direction inclined by ±20° toward the first direction D1 side with respect to the third direction D3, is 10% or less. Further, as shown in FIG. 3, the extending direction of the light transmission 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 a predetermined value or less, so that it is possible to control the light emission angle in the first direction D1. Further, in a state where the light emission angle in the first direction D1 is controlled, since the extending direction of the light transmission portion 3 has an angle θ of 1.5° or more and 20° or less with respect to the second direction D2, it is possible to control the light emission angle in the second direction D2. This is because the viewing angle in the first direction D1 has a very narrow characteristic, and when an angle θ of 1.5° or more and 20° or less is given while maintaining that state, the light transmittance in the second direction D2 rapidly decreases.

[0194] Therefore, when the optical sheet of this embodiment is used in a display device, the light emission angles of the display device in the horizontal and vertical directions can be controlled. More specifically, when used as an optical sheet for a display device arranged in front of the passenger seat of a vehicle, it is possible to control the emission of video light toward the driver side and also to control the reflection of video light on the windshield.

[0195] Other features of the optical sheet in this embodiment are the same as those of the "A-1. Optical Sheet (First Embodiment)" described above, so the description here is omitted.

[0196] B-3. Surface Light Source Device (Fifth Embodiment) The surface light source device 20 of this embodiment includes, for example, as shown in FIGS. 5 to 7, the optical sheet 10E of the fifth embodiment described above and a light source 25 that emits light incident on the optical sheet 10E.

[0197] Details of FIGS. 5 to 7 are described in the section of the above "B-1. Surface Light Source Device (First Embodiment)", so the description here is omitted.

[0198] Regarding the light source and other members of the surface light source device, they are described in the section of the above "B-1. Surface Light Source Device (First Embodiment)", so the description here is omitted.

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

[0200] The display device in this embodiment further has two embodiments. The display device of this embodiment includes a surface light source device, and the surface light source device may include the above-described optical sheet. Also, in the display device of this embodiment, the above-described optical sheet may be arranged on the observer 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 above-described fifth embodiment, and a display panel laminated on the surface light source device.

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

[0203] 1. Surface light source device Since the surface light source device is described in the section of "B-3. Surface light source device (fifth embodiment)", the description thereof will be omitted here.

[0204] 2. Display panel and other members Since the display panel and other members are described in the section of "C-1-1. Display device (first example of the first embodiment)", the description thereof will be omitted here.

[0205] 3. Use Since the use of the display device in this embodiment is the same as the use described in the section of "C-1-1. Display device (first example of the first embodiment)", the 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-described fifth embodiment disposed on the observer side of the display panel.

[0207] Fig. 9 is a schematic plan view and cross-sectional view showing an example of the display device 50J of this embodiment. Since Fig. 9 is described in the section of "C-1-2. Display device (second example of the first embodiment)", the description thereof will be omitted here. As shown in Fig. 9, in the display device 50J in this embodiment, the base material layer 1 in the optical sheet 10I is disposed so as to be on the observer (passenger seat) side with respect to the optical functional layer 2.

[0208] 1. Optical sheet The optical sheet has been described in the section of "A-3. Optical Sheet (Fifth Embodiment)", so the description here is omitted.

[0209] 2. Display Panel and Other Members The display panel and other members have been described in the section of "C-1-2. Display Device (Second Example of the First Embodiment)", so the description here is omitted.

[0210] 3. Applications The applications of the display device in this embodiment are the same as those described in the section of "C-1-1. Display Device (First Example of the First Embodiment)", so the description here is omitted.

[0211] A-4. Optical Sheet (Sixth Embodiment) The optical sheet 10F of this embodiment includes, for example, as shown in FIGS. 1, 3, 4, and 10, a base material layer 1 and an optical functional layer 2 laminated on one surface of the base material layer 1. 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 plan view. The optical functional layer 2 has a plurality of light transmission portions 3 having a predetermined cross-section and extending in one direction, and light absorption portions 4 formed between adjacent light transmission portions 3. The predetermined cross-section of the light transmission portion 3 is trapezoidal, 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 extending direction of the light transmission portion 3 has an angle of 1.5° or more and 20° or less with respect to the second direction D2.

[0212] Details of FIGS. 1, 3, and 4 have been described in the section of "A-1. Optical Sheet (First Embodiment)", so the description here is omitted. Also, regarding FIG. 10, since it has been described in the section of "A-3. Optical Sheet (Fifth Embodiment)", the description here is omitted.

[0213] The optical sheet in this embodiment includes an optical functional layer having a light-transmitting portion and a light-absorbing portion that extend in a predetermined direction and have a predetermined cross-section, thereby reducing the transmittance of light in a direction inclined by ±20° toward the first direction with respect to the third direction. Specifically, when the transmittance of light in the third direction is 100%, the relative transmittance, which is the ratio of the transmittance of light in a direction inclined by ±20° toward the first direction with respect to the third direction, can be set to 10% or less.

[0214] Furthermore, in a state where the light emission angle in the first direction D1 is controlled, by having the extending direction of the light-transmitting portion 3 have an angle θ of 1.5° or more and 20° or less with respect to the second direction D2, it becomes possible to control the light emission angle in the second direction D2.

[0215] Therefore, when the optical sheet of this embodiment is used in a display device, the light emission angles in the left-right direction and the up-down direction of the display device can be controlled. More specifically, when used as an optical sheet for a display device arranged in front of the passenger seat of a vehicle, it is possible to control the emission of video light toward the driver side, and it is also possible to control the reflection of video 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 arranged in front of the passenger seat of a vehicle.

[0217] Other features of the optical sheet in this embodiment are the same as those of the above-described "A-1. Optical Sheet (First Embodiment)", and thus the description here is omitted.

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

[0219] For details of FIGS. 5 to 7, since they are described in the section of "B-1. Surface light source device (first embodiment)" above, the description here is omitted.

[0220] Regarding the light source and other members of the surface light source device, since they are described in the section of "B-1. Surface light source device (first embodiment)" above, the description here is omitted.

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

[0222] The display device in this embodiment further has two embodiments. The display device of this embodiment includes a surface light source device, and the surface light source device may include the above-described optical sheet. Also, in the display device of this embodiment, the above-described optical sheet may be disposed on the observer 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 above-described optical sheet of the sixth embodiment and a display panel laminated on the surface light source device.

[0224] FIGS. 5 to 7 are schematic plan views and cross-sectional views showing an example of the display device 50K of this embodiment. For FIGS. 5 to 7, since they are described in the section of "B-1. Surface light source device (first embodiment)" above, the description here is omitted.

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

[0226] 2. Display panel and other members The display panel and other members are described in the section of "C-1-1. Display device (first example of the first embodiment)" above, so the description here is omitted.

[0227] 3. Use Since the use of the display device in this embodiment is the same as that described in the section of "C-1-1. Display Device (First Example of the First Embodiment)", the description here is omitted.

[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 disposed on the observer side of the display panel.

[0229] FIG. 9 is a schematic plan view and a cross-sectional view showing an example of the display device 50L of this embodiment. Since FIG. 9 has been described in the section of "C-1-2. Display Device (Second Example of the First Embodiment)", the description here is omitted.

[0230] 1. Optical Sheet Since the optical sheet is the same as the optical sheet described in the section of "C-6-1. Display Device (First Example of the Sixth Embodiment)", the description here is omitted.

[0231] 2. Display Panel and Other Members Since the display panel and other members have been described in the section of "C-1-2. Display Device (Second Example of the First Embodiment)", the description here is omitted.

[0232] 3. Use Since the use of the display device in this embodiment is the same as that described in the section of "C-1-1. Display Device (First Example of the First Embodiment)", the description here is omitted.

[0233] C-7. Display Device (Seventh Embodiment) The display device of this embodiment includes an optical sheet and a display panel. The optical sheet includes a base material layer and an optical functional layer laminated on one surface of the base material layer. The optical functional layer has a plurality of light transmission portions that have a predetermined cross-section and extend in one direction, and light absorption portions formed between adjacent light transmission portions. The predetermined cross-section of the light transmission portion is trapezoidal, with the shorter upper base on the light incident side. When the display device is installed, the relative transmittance, which is the ratio of the light transmittance in the direction inclined by ±20° from the normal direction to the left and right in the normal direction of the main surface of the optical sheet, is 10% or less when the light transmittance in the normal direction of the optical sheet is set to 100%. The extending direction of the light transmission 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.

[0234] The display device in this embodiment further has two other embodiments. The display device of this embodiment includes a surface light source device, and the surface light source device may include the above-described optical sheet. Also, in the display device of this embodiment, the above-described optical sheet may be disposed on the observer side of the display panel.

[0235] C-7-1. Display Device (First Example of the Seventh Embodiment) Figs. 5 to 7 are schematic plan views and cross-sectional views showing an example of the display device of the present embodiment. Further, Figs. 1, 3, 4, and 10 are schematic perspective views, cross-sectional views, and plan views showing an example of the optical sheet in the display device of the present embodiment. As shown in Figs. 5 to 7, the display device 50M of the present 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 in the present embodiment includes a base material layer 1 and an optical function layer 2 laminated on one surface of the base material layer 1. The optical function layer 2 has a plurality of light transmission portions 3 having a predetermined cross-section and extending in one direction, and a light absorption portion 4 formed between adjacent light transmission portions 3. A predetermined cross-section of the light transmission portion 3 is trapezoidal, and the short upper base is on the light incident side. As shown in Fig. 10, when the display device 50M is installed, the optical sheet 10G has a relative transmittance, which is the ratio of the light transmittance in the direction inclined by ±20° in the left-right direction from the normal direction N (the third direction D3 in Figs. 1, 3, 4, and 10) of the main surface S of the optical sheet, of 10% or less when the light transmittance in the normal direction N is 100%. Further, as shown in Fig. 3, when the display device 50M is installed, the extending direction of the light transmission portion 3 viewed from the normal direction N of the optical sheet 10G has an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0236] Details of Figs. 1, 3, and 4 are described in the section of "A-1. Optical sheet (First Embodiment)" above, and thus the description here is omitted. Details of Fig. 10 are described in the section of "A-3. Optical sheet (Fifth Embodiment)" above, and thus the description here is omitted. Further, details of Figs. 5 to 7 are described in the section of "B-1. Surface light source device (First Embodiment)" above, and thus the description here is omitted.

[0237] The display device 50M of the present embodiment has a predetermined optical sheet 10G. In the present embodiment, since the relative transmittance, which is the ratio of the light transmittance in the direction inclined by ±20° in the left-right direction with respect to the normal direction, is equal to or less than a predetermined value when the display device is installed, the light emission angle of the display device in the left-right direction can be controlled. Further, in a state where the light emission angle in the left-right direction is controlled, since the extending direction of the light transmission portion viewed from the normal direction has a predetermined range of angle θ with respect to the vertical direction, the light emission angle of the display device in the up-down direction can be controlled.

[0238] Therefore, it becomes a display device capable of controlling the light emission angles in the left-right direction and the up-down direction. More specifically, when arranged in front of the passenger seat of a vehicle, it is possible to control the emission of video light toward the driver's side and to control the reflection of video 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. In the present embodiment, as shown in FIGS. 1, 3, 4, and 10, 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 is set to 100%, the relative transmittance, which is the ratio of the light transmittance in the direction inclined by ±20° in the left-right direction from the normal direction N, is 10% or less. The relative transmittance of the above light is preferably 5% or less.

[0240] Furthermore, when the display device is installed, the optical sheet in the present embodiment has an angle of 1.5° or more and 20° or less between the extending direction of the light-transmitting portion as viewed from the normal direction and the vertical direction. The angle θ is 1.5° or more, and may be 5° or more, or may be 10° or more. On the other hand, the angle θ is 20° or less, and may be 15° or less. By having the angle θ within the above range, it becomes possible to control the light-emitting angle in the left-right direction. In FIGS. 1 and 3, the light-transmitting portion 3 has an angle θ to 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 to 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] In the present embodiment, the features of the optical sheet having the above optical characteristics and other features are the same as those of the above-described "A-1. Optical Sheet (First Embodiment)", so the description here is omitted. As other members of the surface light source device, since they are described in the section of the above "B-1. Surface Light Source Device (First Embodiment)", the description here is omitted.

[0242] 2. Display Panel and Other Members The display panel and other members are described in the section of the above "C-1-1. Display Device (First Example of the First Embodiment)", so the description here is omitted.

[0243] 3. Applications The application of the display device in the present embodiment is the same as that of the above-described "C-1-1. Display Device (First Example of the First Embodiment)", so the description here is omitted.

[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 the present embodiment. FIGS. 1, 3, 4, and 10 are schematic perspective views, cross-sectional views, and plan views showing an example of the optical sheet in the display device of the present embodiment. As shown in FIG. 9, the display device 50N of the present embodiment includes a display panel 30 and an optical sheet 10G disposed on the observer side of the display panel 30. As shown in FIGS. 1, 3, 4, and 10, the optical sheet 10G in the present embodiment includes a base material layer 1 and an optical functional layer 2 laminated on one surface of the base material layer 1. The optical functional layer 2 has a plurality of light transmission portions 3 having a predetermined cross-section and extending in one direction, and a light absorption portion 4 formed between adjacent light transmission portions 3. A predetermined cross-section of the light transmission portion 3 is trapezoidal, and the short upper base is the light incident side. As shown in FIG. 10, when the display device 50N is installed, the optical sheet 10G has a relative transmittance, which is the ratio of the light transmittance in the direction inclined ±20° in the left-right direction from the normal direction N (the third direction D3 in FIGS. 1 to 4) of the main surface S of the optical sheet, of 10% or less when the light transmittance in the normal direction N is 100%. Also, as shown in FIG. 3, when the display device 50N is installed, the extending direction of the light transmission portion 3 viewed from the normal direction N of the optical sheet 10G 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 in the section of "A-1. Optical Sheet (First Embodiment)" above, so the description here is omitted. Details of FIG. 10 are described in the section of "A-3. Optical Sheet (Fifth Embodiment)" above, so the description here is omitted. Also, details of FIG. 9 are described in the section of "C-1-2. Display Device (Second Example of First Embodiment)" above, so the description here is omitted.

[0246] 1. Optical Sheet The optical sheet is the same as the optical sheet described in the section of "C-7-1. Display Device (First Example of Seventh Embodiment)" above, so the description here is omitted.

[0247] 2. Display Panel and Other Members The display panel and other members are described in the section of "C-1-2. Display Device (Second Example of the First Embodiment)" above, so the description here is omitted.

[0248] 3. Applications The applications of the display device in this embodiment are the same as those of the "C-1-1. Display Device (First Example of the First Embodiment)" described above, so the description here is omitted.

[0249] C-8. Display Device (Eighth Embodiment) The display device of this embodiment includes an optical sheet and a display panel, and is a display device arranged in front of the passenger seat of a vehicle. The optical sheet includes a base material layer and an optical function layer laminated on one surface of the base material layer. The base material layer is a resin base material, and the optical function layer has a plurality of light transmission portions having a predetermined cross-section and extending in one direction, and light absorption portions formed between adjacent light transmission portions. The predetermined cross-section of the light transmission portion is trapezoidal, with the short upper base on the light incident side. The optical sheet is a display device in which the extending direction of the light transmission portion 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 when the display device is installed in front of the passenger seat of the vehicle.

[0250] The display device in 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. Also, in the display device of this embodiment, the above-mentioned optical sheet may be arranged on the observer side of the display panel.

[0251] C-8-1. Display Device (First Example of the Eighth Embodiment) Figs. 5 to 7 are schematic plan views and cross-sectional views showing an example of the display device of the present embodiment. Further, Figs. 1, 3, 4, and 10 are schematic perspective views, cross-sectional views, and plan views showing an example of the optical sheet in the display device of the present embodiment. As shown in Figs. 5 to 7, the display device 50O in the present embodiment 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 a display device disposed in front of the passenger seat of a vehicle. As shown in Figs. 1, 3, 4, and 10, the optical sheet 10H in the present 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, and the optical functional layer 2 has a plurality of light transmission portions 3 having a predetermined cross-section and extending in one direction, and light absorption portions 4 formed between adjacent light transmission portions 3. A predetermined cross-section of the light transmission portion 3 is trapezoidal, and the short upper base is on the light incident side. When the display device is installed in front of the passenger seat of the vehicle, the optical sheet 10H has an extending direction of the light transmission portion 3 viewed from the normal direction N (the third direction D3 in Figs. 1 to 4) of the main surface of the optical sheet 10H at an angle of 1.5° or more and 20° or less with respect to the vertical direction.

[0252] The display device 50O in the present embodiment has a predetermined optical sheet 10H. By including an optical functional layer having a light transmission portion and a light absorption portion that extend in a predetermined direction and have a predetermined cross-section, when the display device is installed in front of the passenger seat of the vehicle, the transmittance of light in a direction inclined by ±20° in the left-right direction with respect to the normal direction can be reduced. Specifically, when the transmittance of light in the normal direction is 100%, the relative transmittance, which is the ratio of the transmittance of light in a direction inclined by ±20° to the left and right with respect to the normal direction, can be set to 10% or less. Therefore, it is possible to control the light emission angle in the left-right direction of the display device.

[0253] Furthermore, in a state where the light emission angle in the left - right direction is controlled, since the extending direction of the light - transmitting portion as viewed from the normal direction has an angle θ within a predetermined range with respect to the vertical direction, it becomes possible to control the light emission angle in the up - down direction of the display device. Therefore, the display device of the present embodiment can control the emission of video light toward the driver's side and can also control the reflection of video 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 the present embodiment includes an optical functional layer having a light - transmitting portion and a light - absorbing portion that extend in a predetermined direction and have a predetermined cross - section. Thereby, when the display device 50O having the predetermined optical sheet 10H is installed in front of the passenger seat of the vehicle, 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 set to 100%, the relative transmittance, which is the ratio of the light transmittance in the direction inclined by ±20° from the normal direction N to the left - right direction, can be set to 10% or less. The relative transmittance of the above - mentioned light is preferably 5% or less.

[0255] Furthermore, in the optical sheet of the present embodiment, when the display device is installed in front of the passenger seat of the vehicle, the extending 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 may be 1.5° or more, may be 5° or more, or may be 10° or more. On the other hand, the angle θ may be 20° or less, or may be 15° or less. By the angle θ being within the above - mentioned range, it becomes possible to control the light emission angle in the left - right 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 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 the above-described "A-1. Optical Sheet (First Embodiment)", and thus the description here is omitted. Other members of the surface light source device are described in the section of the above "B-1. Surface Light Source Device (First Embodiment)", and thus the description here is omitted.

[0257] 2. Display Panel and Other Members The display panel and other members are described in the section of the above "C-1-1. Display Device (First Example of the First Embodiment)", and thus the description here is omitted.

[0258] 3. Applications The display device in this embodiment is arranged in front of the passenger seat of a vehicle. FIG. 8(a) is a schematic view of the front inside of the vehicle when the display device 50O in this embodiment is arranged 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 left-right direction in the optical sheet is the horizontal direction (the left-right direction of the vehicle), the up-down direction is the vertical direction, and the thickness direction is the horizontal direction (the front-rear direction of the vehicle). On the other hand, 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 the present embodiment. FIGS. 1, 3, 4, and 10 are schematic perspective views, cross-sectional views, and plan views showing an example of the optical sheet in the display device of the present embodiment. As shown in FIG. 9, the display device 50P of the present embodiment includes a display panel 30 and an optical sheet 10H disposed on the observer side of the display panel 30. As shown in FIGS. 1, 3, 4, and 10, the optical sheet 10H in the present embodiment includes a base material layer 1 and an optical functional layer 2 laminated on one surface of the base material layer 1. The optical functional layer 2 has a plurality of light transmission portions 3 having a predetermined cross-section and extending in one direction, and a light absorption portion 4 formed between adjacent light transmission portions 3. A predetermined cross-section of the light transmission portion 3 is trapezoidal, and the short upper base is on the light incident side. As shown in FIG. 3, when the display device 50P is installed, the extending direction of the light transmission portion 3 viewed from the normal direction N has 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 in the section of "A-1. Optical Sheet (First Embodiment)" above, so the description here is omitted. Since FIG. 10 is described in the section of "A-3. Optical Sheet (Fifth Embodiment)" above, the description here is omitted. Also, since FIG. 9 is described in the section of "C-1-2. Display Device (Second Example of First Embodiment)" above, the description here is omitted.

[0261] 1. Optical Sheet The optical sheet is the same as the optical sheet described in the section of "C-8-1. Display Device (First Example of Eighth Embodiment)" above, so the description here is omitted.

[0262] 2. Display Panel and Other Members The display panel and other members are described in the section of "C-1-2. Display Device (Second Example of First Embodiment)" above, so the description here is omitted.

[0263] 3. Use The use of the display device in the present embodiment is the same as that in "C-8-1. Display Device (First Example of Eighth Embodiment)" above, so the description here is omitted.

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

Example

[0265] Examples and comparative examples are shown below to explain the present disclosure in more detail.

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

[0267] Regarding the obtained optical sheet, the luminance of light was measured as follows, and the transmittance and relative transmittance were calculated.

[0268] (Measurement method) First, without placing the optical sheet, the luminance of the light in the third direction D3 of a surface light source (an edge-lit type surface light source using an LED as the light source) alone was measured using a viewing angle characteristic measurement device (EZ Contrast XL80 manufactured by ELDIM). Next, the surface light source (an edge-lit type surface light source using an LED as the light source) was placed on the back side (the side of the optical functional layer) 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 the direction inclined by ±30° toward the first direction D1 with respect to the third direction D3 were measured on the front side (the side of the base material layer) using the viewing angle characteristic measurement 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 in the third direction D3 of the surface light source alone was 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 the direction inclined by ±30° toward the first direction D1 with respect to the third direction D3 to the luminance of the light in the third direction D3 of the surface light source alone was calculated as the transmittance of the light transmitted in the direction inclined by ±30° toward the first direction D1 with respect to the third direction D3. Finally, the relative transmittance, which is the ratio of the transmittance of the light transmitted in the direction inclined by ±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 is set to 100%, was calculated. The results are shown in Tables 1 and 2.

[0269] Also, in the same manner as above, the relative transmittance, which is the ratio of the transmittance of the light transmitted in the direction inclined by ±20° 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 is set to 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 FIGS. 12(a) and 13(a). FIG. 12(a) shows that the horizontal axis represents the viewing angle in the left-right direction (first direction D1), and the vertical axis represents the ratio of the light transmittance at each viewing angle in the left-right direction (relative transmittance) 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 had 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] FIG. 13(a) shows that the horizontal axis represents the viewing angle in the up-down direction (second direction D2), and the vertical axis represents the ratio of the light transmittance at each viewing angle in the up-down direction (relative transmittance) 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 18% at a viewing angle of ±30° in the second direction D2. On the other hand, the optical sheet of Comparative Example 8 obtained 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 obliquely from a position where the horizontal viewing angle was about 30°. Fig. 12(b) shows how the display device was observed. In Comparative Example 8, video light was visible from a position where the horizontal viewing angle was about 30°, whereas in Example 4, it was confirmed that the video light was not visible from a position where the horizontal viewing angle was about 30°.

[0277] Assuming the case where the optical sheets of Examples 1 to 18 and Comparative Examples 1 to 14 were used in the passenger seat display device, the presence or absence of reflection of video light on the front glass in front of the passenger seat was observed. In Comparative Example 8, reflection of video light on the front glass was observed, whereas in Example 4, it was confirmed that the reflection was suppressed (Fig. 13(b)). Also, the presence or absence of reflection on the front glass when using the optical sheets of other examples and comparative examples is shown in Table 1 and Table 2. From Table 1 and Table 2, it was confirmed that when the relative transmittance, which is the ratio of the transmittance of light in a direction inclined by ±30° to the second direction side with respect to the third direction when the transmittance of light in the third direction is 100%, is 32% or less, the reflection on the front glass is suppressed.

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

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

[11] The surface light source device according to

[10] , and A display device including a display panel laminated on the surface light source device.

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

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

[14] When the above display device is installed in front of the passenger seat of a vehicle, The display device according to

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

[15] The display device according to any one of

[12] to

[14] , wherein the above display device includes a surface light source device, and the above surface light source device includes the above optical sheet.

[16] The display device according to any one of

[12] to

[14] , wherein the above optical sheet is disposed on the observer side of the above 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 Signs

[0279] 1... Substrate layer 2... Optical functional layer 3... Light transmission portion 4... Light absorption portion 10... Optical sheet 15... Liquid crystal panel 20... Surface light source device 21... Light guide plate 25... Light source 26... Light diffusing plate 27… Prism layer 28… Reflective polarizing plate 50… Display device

Claims

Claim 1 An optical sheet comprising a base material layer and an optical functional layer laminated on one surface of the base material layer, the optical sheet having a rectangular shape having a pair of first sides extending in a first direction and a pair of second sides extending in a second direction in plan view, the optical functional layer having a plurality of light transmission portions having a predetermined cross section and extending in one direction, and light absorption portions formed between adjacent ones of the light transmission portions, the predetermined cross section of the light transmission portion being trapezoidal with the short upper base on the light incident side, the relative transmittance, which is the ratio of the transmittance of light in a direction inclined by ±20° to the first direction side with respect to the third direction, when the transmittance of light in the third direction orthogonal to the first direction and the second direction is 100%, being 10% or less, the optical sheet, wherein the extending direction of the light transmission portion has an angle of 1.5° or more and 20° or less with respect to the second direction.

Images