Display device and production method for display device

Abstract

[Problem] To minimize the luminance of light, emitted from a light-emitting part and reflected at an end part of a member covering the light-emitting part, that reaches a user's eyes. [Solution] A display device (1) comprises a light-emitting substrate (10) that has a semiconductor layer (11) and a light-emitting part (13), and an optical sheet (20). The optical sheet (20) has a plurality of unit lenses (21). In a first cross-section, defining H1 as the length of a first side (131), D1 as the distance between the light-emitting part (13) and an end part (2a) of a covering part (2) in a second direction, and Y1 as the distance between the light-emitting part (13) and a lens surface (21a) of a unit lens (21), one among the following applies: the refractive index n of the covering part (2) is 1.4 to less than 1.5 and formula (1) is satisfied; the refractive index n of the covering part (2) is 1.5 to less than 1.6 and formula (2) is satisfied; and the refractive index n of the covering part (2) is 1.6 or higher and formula (3) is satisfied.

Description

Display device and method for manufacturing the same

[0001] The present disclosure relates to a display device and a method for manufacturing a display device.

[0002] In recent years, display devices equipped with multiple light-emitting elements, particularly display devices equipped with LEDs, so-called LED displays, have become known. In particular, display devices using a semiconductor on which multiple tiny light-emitting diodes (LEDs) and wiring are formed as a light-emitting substrate, so-called micro LED displays, have been developed. Micro LED displays have attracted attention as small, lightweight, and thin displays. Organic light-emitting diode (OLED) displays equipped with organic EL elements are also known.

[0003] Furthermore, the above-mentioned display devices, particularly micro LED displays, have the problem that the light emitted from the light-emitting diodes is diffused light, making it difficult to use the light efficiently. To address this problem, for example, Patent Document 1 discloses a micro LED display that focuses light in a specific direction, such as the front direction, by providing an array lens, particularly a linear array lens, on the light-emitting side. Focusing light in a specific direction allows for efficient use of the light emitted from the LEDs.

[0004] Japanese Patent Application Laid-Open No. 2019-197133

[0005] In a display device, light emitted from a light-emitting unit may be reflected at the edge of a member covering the light-emitting unit, such as an optical sheet, and then reach the user's eyes. In this case, if the brightness of the light reflected at the edge of the member covering the light-emitting unit and reaching the user's eyes increases, it may hinder the user from viewing the display of the display device. For this reason, it may be necessary to reduce the brightness of the light emitted from the light-emitting unit, reflected at the edge of the member covering the light-emitting unit, and reaching the user's eyes.

[0006] The present invention has been made taking these points into consideration, and aims to reduce the brightness of light that is emitted from the light-emitting unit, reflected at the end of the member covering the light-emitting unit, and reaches the user's eyes.

[0007] Embodiments of the present disclosure relate to the following [1] to

[10] .

[0008] [1] A light emitting substrate having a semiconductor layer divided into a plurality of unit areas and light emitting sections arranged in the plurality of unit areas; and a covering section including an optical sheet arranged opposite the light emitting substrate and covering the light emitting sections, wherein the optical sheet has a plurality of unit lenses arranged in a first direction and extending in a second direction non-parallel to the first direction, the plurality of unit areas being aligned in the first direction and the second direction, and in a first cross section passing through the light emitting sections and parallel to the second direction and a thickness direction of the optical sheet, the light emitting sections have a rectangular shape including a first side extending in the thickness direction of the optical sheet and a second side extending in the second direction and having a length equal to or greater than the length of the first side, a display device in which, in the first cross section, the length of the first side is H1, the distance between the end of the covering portion and the light-emitting portion in the second direction is D1, and the distance between the lens surface of the unit lens and the light-emitting portion is Y1, and any one of the following is true: a refractive index n of the covering portion is 1.4 or more and less than 1.5 and the following formula (1) is satisfied; a refractive index n of the covering portion is 1.5 or more and less than 1.6 and the following formula (2) is satisfied; or a refractive index n of the covering portion is 1.6 or more and the following formula (3) is satisfied.

[0009] [2] A light emitting substrate having a semiconductor layer divided into a plurality of unit areas and light emitting sections arranged in the plurality of unit areas; and a covering section including an optical sheet arranged opposite to the light emitting substrate and covering the light emitting sections, wherein the optical sheet has a plurality of unit lenses arranged in a first direction and extending in a second direction non-parallel to the first direction, the plurality of unit areas are aligned in the first direction and the second direction, and in a first cross section passing through the light emitting sections and parallel to the second direction and a thickness direction of the optical sheet, the light emitting sections have a rectangular shape including a first side extending in the thickness direction of the optical sheet and a second side extending in the second direction and having a length equal to or greater than the length of the first side, In the first cross section, when the length of the first side is H1, the distance between the end of the covering portion and the light-emitting portion in the second direction is D1, and the distance between the lens surface of the unit lens and the light-emitting portion is Y1, any one of the following is true: the refractive index n of the covering portion is 1.4 or more and less than 1.5 and the following formula (4) is satisfied; the refractive index n of the covering portion is 1.5 or more and less than 1.6 and the following formula (5) is satisfied; or the refractive index n of the covering portion is 1.6 or more and the following formula (6) is satisfied.

[0010] [3] The display device according to claim 1 or 2, wherein in a cross section perpendicular to the second direction, the unit lenses have a shape corresponding to a part of a circle or a part of an ellipse.

[0011] [4] The display device according to claim 1 or 2, wherein in the first cross section, a dimension of the end of the covering portion in the thickness direction of the optical sheet is smaller than a maximum dimension of the covering portion in the thickness direction of the optical sheet.

[0012] [5] The display device described in claim 4, wherein the covering portion has an end region that extends in the second direction and includes the end of the covering portion, and in the first cross section, the dimension of the covering portion in the thickness direction of the optical sheet gradually decreases along the second direction within the end region toward the end of the covering portion.

[0013] [6] The display device according to claim 1, wherein the unit lenses are linear Fresnel lenses.

[0014] [7] A display including a plurality of the display devices according to claim 1 or 2, wherein the plurality of display devices are arranged so as to be in contact with each other at least in the second direction.

[0015] [8] A light emitting substrate having a semiconductor layer divided into a plurality of unit areas and light emitting portions arranged in the plurality of unit areas; and a covering portion including an optical sheet arranged opposite to the light emitting substrate and covering the light emitting portions, wherein the optical sheet has a sheet-like main body and a plurality of isolated lenses arranged on a surface of the main body, and in a second cross section passing through the light emitting portions and parallel to the thickness direction of the optical sheet, the light emitting portions have a rectangular shape including a third side extending in the thickness direction of the optical sheet and a fourth side orthogonal to the third side and having a length equal to or greater than the length of the third side, a display device in which, in the second cross section, a length of the third side is H2, a distance between the end of the covering portion and the light-emitting portion in a direction perpendicular to the thickness direction of the optical sheet is D2, and a distance between the boundary between the main body portion and the isolated lens and the light-emitting portion in the thickness direction of the optical sheet is Y2, and any one of the following is true: a refractive index n of the covering portion is 1.4 or more and less than 1.5 and the following formula (7) is satisfied; a refractive index n of the covering portion is 1.5 or more and less than 1.6 and the following formula (8) is satisfied; or a refractive index n of the covering portion is 1.6 or more and the following formula (9) is satisfied.

[0016] [9] A light emitting substrate having a semiconductor layer divided into a plurality of unit areas and light emitting portions arranged in the plurality of unit areas; and a covering portion including an optical sheet arranged opposite to the light emitting substrate and covering the light emitting portions, wherein the optical sheet has a sheet-like main body and a plurality of isolated lenses arranged on a surface of the main body, and in a second cross section passing through the light emitting portions and parallel to the thickness direction of the optical sheet, the light emitting portions have a rectangular shape including a third side extending in the thickness direction of the optical sheet and a fourth side orthogonal to the third side and having a length equal to or greater than the length of the third side, a display device in which, in the second cross section, a length of the third side is H2, a distance between the end of the covering portion and the light-emitting portion in a direction perpendicular to the thickness direction of the optical sheet is D2, and a distance between the boundary between the main body portion and the isolated lens and the light-emitting portion in the thickness direction of the optical sheet is Y2, and any one of the following is true: a refractive index n of the covering portion is 1.4 or more and less than 1.5 and the following formula (10) is satisfied; a refractive index n of the covering portion is 1.5 or more and less than 1.6 and the following formula (11) is satisfied; or a refractive index n of the covering portion is 1.6 or more and the following formula (12) is satisfied.

[0017]

[10] A display including a plurality of the display devices according to claim 8 or 9, wherein the plurality of display devices are arranged so as to be in contact with each other.

[0018] According to the present disclosure, the brightness of light that is emitted from the light-emitting unit, reflected at the edge of the member that covers the light-emitting unit, and reaches the user's eyes can be kept low.

[0019] FIG. 1 is an exploded perspective view schematically showing each element of the display device. FIG. 2 is a cross-sectional view showing an enlarged portion of the light-emitting substrate of the display device. FIG. 3 is a plan view showing an enlarged portion of the light-emitting substrate of the display device. FIG. 4 is a cross-sectional view of the display device taken along line IV-IV in FIG. 3. FIG. 5 is a cross-sectional view of the display device taken along line V-V in FIG. 3. FIG. 6 is a diagram for explaining the simulation test method. FIG. 7a is a graph showing the ratio of the brightness of the double image to the brightness of the direct image in the simulation test. FIG. 7b is a graph showing the ratio of the brightness of the double image to the brightness of the direct image in the simulation test. FIG. 7c is a graph showing the ratio of the brightness of the double image to the brightness of the direct image in the simulation test. FIG. 8a is a diagram showing the correspondence relationship between the distance D1 and the distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50%, obtained from the results of the simulation test. Figure 8b is a diagram showing the correspondence relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50%, obtained from the results of a simulation test. Figure 8c is a diagram showing the correspondence relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50%, obtained from the results of a simulation test. Figure 9 is a diagram for explaining the theoretical basis of the derived conditions. Figure 10 is a diagram for explaining the theoretical basis of the derived conditions. Figure 11a is a diagram for explaining the theoretical basis of the derived conditions. Figure 11b is a diagram for explaining the theoretical basis of the derived conditions. Figure 12a is a diagram showing a method for manufacturing a display device. Figure 12b is a diagram showing a method for manufacturing a display device. Figure 12c is a cross-sectional view of a display. Figure 13a is a perspective view showing a unit lens in a display device of Modification 1. Figure 13b is a cross-sectional view of the display device of Modification 1. Figure 14 is a cross-sectional view of a display device of Modification 2. Figures 15a, 15b, and 15c are graphs showing the ratio of the brightness of the double image to the brightness of the direct image in a simulation test.Figure 16a is a diagram showing the correspondence relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50%, obtained from the results of a simulation test. Figure 16b is a diagram showing the correspondence relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50%, obtained from the results of a simulation test. Figure 16c is a diagram showing the correspondence relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50%, obtained from the results of a simulation test. Figure 17 is a plan view showing an optical sheet of a display device of variant 4. Figure 18 is a cross-sectional view of the display device of variant 4. Figure 19 is a cross-sectional view of the display of variant 4.

[0020] An embodiment will be described below with reference to the drawings. FIGS. 1 to 12c are diagrams illustrating one embodiment. Each of the following figures is a schematic illustration. Therefore, the size and shape of each part are appropriately exaggerated to facilitate understanding. Furthermore, appropriate modifications can be made without departing from the technical concept. In each of the following figures, the same parts are denoted by the same reference numerals, and some detailed descriptions may be omitted. Furthermore, the numerical values, such as dimensions, and material names of each member described in this specification are merely examples of an embodiment, and are not limited to these, and may be selected and used as appropriate.

[0021] In addition, "plate surface" refers to a surface that coincides with the planar direction of the target plate-shaped (sheet-shaped, film-shaped) member when viewed overall and from a global perspective.

[0022] Furthermore, terms used in this specification that specify shapes, geometric conditions, and their degrees, such as "parallel," "orthogonal," "perpendicular," "identical," "similar," and values ​​of lengths and angles, are not to be construed as being bound by strict meanings, but rather as including the range of degrees to which similar functions can be expected.

[0023] FIG. 1 is an exploded perspective view schematically illustrating a display device 1 according to the present embodiment. A sealing layer 40 and an adhesive layer 50, which will be described later, are not illustrated in FIG. 1 . As shown in FIG. 1 , the display device 1 includes a light-emitting substrate 10 and a covering unit 2. The covering unit 2 includes an optical sheet 20 disposed opposite the light-emitting substrate 10. In the example shown in FIG. 1 , the optical sheet 20 has a surface facing the light-emitting substrate 10 and a surface located opposite the surface. The display device 1 according to the present embodiment is, for example, a display device equipped with LEDs, a so-called LED display. Below, a case will be described in which the display device 1 is a so-called micro LED display that uses light emitted from one or more light-emitting diodes as one pixel.

[0024] The light emitting substrate 10 emits light that forms an image. Fig. 2 is an enlarged cross-sectional view showing the configuration of the light emitting substrate 10. As shown in Fig. 2, the light emitting substrate 10 has a semiconductor layer 11 and a plurality of light emitting sections 13 provided on the semiconductor layer 11. In the example shown in Fig. 2, each light emitting section 13 includes an active layer 14 in contact with the semiconductor layer 11 and a second semiconductor layer 15 in contact with the active layer 14. That is, at the position of the light emitting substrate 10 where the light emitting section 13 is provided, the semiconductor layer 11, the active layer 14, and the second semiconductor layer 15 are stacked in this order.

[0025] The active layer 14 can emit light by applying a voltage between the semiconductor layer 11 and the second semiconductor layer 15. In order to apply a voltage between the semiconductor layer 11 and the second semiconductor layer 15, electrodes (not shown) are provided on the semiconductor layer 11 and the second semiconductor layer 15, and are connected to an external power supply via a circuit formed in the semiconductor layer 11. Light generated by the emission of light by the active layer 14 is emitted to the outside of the light emitting section 13 through the surface of the light emitting section 13.

[0026] In this embodiment, the light-emitting substrate 10 includes, as the light-emitting unit 13, a first light-emitting unit 13R that emits light of a certain wavelength and a second light-emitting unit 13G that emits light of a wavelength different from that of the first light-emitting unit 13R. In the example shown in Fig. 2, the light-emitting substrate 10 further includes, as the light-emitting unit 13, a third light-emitting unit 13B that emits light of a wavelength different from that of the first light-emitting unit 13R and the second light-emitting unit 13G. The light-emitting substrate 10 includes, as the multiple light-emitting units 13, a plurality of first light-emitting units 13R, a plurality of second light-emitting units 13G, and a plurality of third light-emitting units 13B. The first light-emitting unit 13R, the second light-emitting unit 13G, and the third light-emitting unit 13B are light-emitting diodes.

[0027] FIG. 3 is an enlarged plan view showing a portion of the light-emitting substrate 10 of the display device 1. As shown in FIGS. 2 and 3, the semiconductor layer 11 is divided into a plurality of unit regions 10a. In the example shown in FIG. 3, the unit regions 10a are aligned in a first direction d1 and a second direction d2 non-parallel to the first direction d1. In the example shown, the first direction d1 and the second direction d2 are perpendicular to each other. In the example shown, the plurality of unit regions 10a are aligned so as to be in contact with each other in the first direction d1 and the second direction d2. In FIG. 3, one unit region 10a is indicated by diagonal lines. The light-emitting unit 13 is arranged in the plurality of unit regions 10a. In the example shown, the light-emitting unit 13 is arranged in all of the unit regions 10a. One light-emitting unit 13 is arranged in one unit region 10a. In the example shown, the light-emitting unit 13 is arranged in the center of the unit region 10a. The light-emitting portions 13 are arranged at equal intervals in the first direction d1 and the second direction d2.

[0028] In the example shown in Fig. 3, the light-emitting substrate 10 has a first light-emitting portion 13R, a second light-emitting portion 13G, and a third light-emitting portion 13B as the light-emitting portions 13. In the example shown in Fig. 3, one unit area set 10b of the light-emitting substrate 10 includes one unit area 10a in which the first light-emitting portion 13R is arranged, one unit area 10a in which the second light-emitting portion 13G is arranged, and one unit area 10a in which the third light-emitting portion 13B is arranged. In the example shown in Fig. 3, the light-emitting substrate 10 has multiple unit area sets 10b arranged in the first direction d1 and the second direction d2. In one unit area set 10b, the unit area 10a in which the first light-emitting portion 13R is arranged, the unit area 10a in which the second light-emitting portion 13G is arranged, and the unit area 10a in which the third light-emitting portion 13B is arranged are arranged in the second direction d2. The unit area sets 10b form pixel areas of the display device 1. The light-emitting sections 13 arranged in each unit area set 10b form pixels of the display device 1. The configuration of the light-emitting substrate 10 is not limited to the example shown in Fig. 3 in which the light-emitting sections 13 include a first light-emitting section 13R, a second light-emitting section 13G, and a third light-emitting section 13B. The configuration of the light-emitting substrate 10 can be any commonly known configuration of a light-emitting substrate 10 having light-emitting sections 13, without any particular limitations.

[0029] As described below, the optical sheet 20 of this embodiment has a plurality of unit lenses 21 arranged in a first direction d1 and extending in a second direction d2. In the example shown in FIG. 3 , the width of each unit region 10a in the first direction d1, which is the direction in which the plurality of unit lenses 21 described below are arranged, is larger than the width of each unit region 10a in the second direction d2, in which the unit lenses 21 extend. The width of each light-emitting section 13 in the first direction d1 is larger than the width of each light-emitting section 13 in the second direction d2. Although not shown, the width of each unit region 10a in the first direction d1, which is the direction in which the plurality of unit lenses 21 described below are arranged, may be smaller than the width of each unit region 10a in the second direction d2, in which the unit lenses 21 extend. Although not shown, the width of each light-emitting section 13 in the first direction d1 may be smaller than the width of each light-emitting section 13 in the second direction d2. In the example shown in FIG. 3 , the unit lenses 21 are arranged in one unit area set 10b so as to extend in the direction in which the first light-emitting unit 13R, the second light-emitting unit 13G, and the third light-emitting unit 13B are aligned. However, the arrangement of the unit lenses 21 is not limited to this. The unit lenses 21 may be arranged so as to extend in a direction different from the direction in which the first light-emitting unit 13R, the second light-emitting unit 13G, and the third light-emitting unit 13B are aligned. Furthermore, the unit lenses 21 may be arranged so as to overlap with the light-emitting units 13 of the light-emitting substrate 10 that do not include the first light-emitting unit 13R, the second light-emitting unit 13G, and the third light-emitting unit 13B.

[0030] FIG. 4 is a cross-sectional view of the display device 1 taken along line IV-IV in FIG. 3. FIG. 4 particularly illustrates an enlarged view of the periphery of an end 2a of the covering 2 of the display device 1, which will be described later. As shown in FIGS. 3 and 4, the pitch of the light-emitting units 13 in the first direction d1 is defined as p. The dashed lines labeled C1 in FIGS. 3 and 4 indicate the centers of the light-emitting units 13 in the first direction d1. The pitch p of the light-emitting units 13 is the distance from the center C1 of the light-emitting unit 13 in a unit region 10a in the first direction d1 to the center C1 of the light-emitting unit 13 in the first direction d1 of the unit region 10a adjacent to the unit region 10a in the first direction d1. The pitch p of the light-emitting units 13 is, for example, 10 μm or more and 2000 μm or less. The pitch p of the light-emitting units 13 may be 10 μm or more and 500 μm or less. Furthermore, the length of each unit region 10a along the first direction d1 and the second direction d2 is, for example, 10 μm or more and 2000 μm or less. In the example shown in FIG. 4, the length of each unit region 10a along the first direction d1 is equal to the pitch p of the light-emitting portions 13. As shown in FIGS. 3 and 4, the width of each light-emitting portion 13 in the first direction d1 is defined as w. In other words, the width w of each light-emitting portion 13 is the length of each light-emitting portion 13 along the first direction d1. The width w of each light-emitting portion 13 is, for example, 1 μm or more and 1200 μm or less. The length of each light-emitting portion 13 along the second direction d2 is, for example, 1 μm or more and 1200 μm or less.

[0031] The shape of the light-emitting unit 13 is not limited as long as it satisfies the shape conditions in the first cross section described below. As an example, the shape of the light-emitting unit 13 is a rectangular parallelepiped. The light-emitting unit 13 has a pair of faces parallel to the first direction d1 and the second direction d2, a pair of faces parallel to the first direction d1 and a thickness direction d3 of the optical sheet 20 described below, and a pair of faces parallel to the second direction d2 and the thickness direction d3. The rectangular parallelepiped includes a cube. In other words, the shape of the light-emitting unit 13 may be a cube.

[0032] The covering unit 2 covers the light-emitting unit 13 of the light-emitting substrate 10. In this embodiment, the covering unit 2 covers the light-emitting unit 13 and also covers the surface of the semiconductor layer 11 on which the light-emitting unit 13 is provided. In this embodiment, the covering unit 2 covers the entire surface of the semiconductor layer 11 on which the light-emitting unit 13 is provided. The refractive index n of the covering unit 2 formed from a general material is 1.4 or more. As will be described later, when the covering unit 2 is made of multiple components, if the refractive indexes of all of the multiple components are A1 or more, it can be said that the refractive index n of the covering unit 2 is A1 or more. As will be described later, when the covering unit 2 is made of multiple components, if the refractive indexes of all of the multiple components are A2 or less, it can be said that the refractive index n of the covering unit 2 is A2 or less. For example, when the covering unit 2 is made of an optical sheet 20, a sealing layer 40, and an adhesive layer 50, if the refractive indexes of the optical sheet 20, the sealing layer 40, and the adhesive layer 50 are all A1 or more and A2 or less, it can be said that the refractive index n of the covering unit 2 is A1 or more and A2 or less. As will be described later, when the covering portion 2 is composed only of the optical sheet 20, if the refractive index of the optical sheet 20 is equal to or greater than A1 and equal to or less than A2, it can be said that the refractive index n of the covering portion 2 is equal to or greater than A1 and equal to or less than A2. The refractive index in this specification can be represented by the refractive index at the dominant wavelength in the display device 1. Specifically, the dominant wavelength in the display device 1 can be selected to be the wavelength to which the human eye is most sensitive.

[0033] As shown in FIG. 2 , the covering portion 2 has an end portion 2a in a direction perpendicular to the thickness direction d3 of the optical sheet 20. In particular, the covering portion 2 has an end portion in the second direction d2. In this embodiment, the end portion 2a of the covering portion 2 in the second direction d2 is referred to as a first end portion 2b. The first end portion 2b includes an end portion of the optical sheet 20 in the second direction d2. As an example, the covering portion 2 includes the optical sheet 20, the sealing layer 40, and the adhesive layer 50. In this case, the first end portion 2b includes an end portion of the optical sheet 20 in the second direction d2, an end portion of the sealing layer 40 in the second direction d2, and an end portion of the adhesive layer 50 in the second direction d2. In particular, the first end portion 2b includes an end portion of the unit lenses 21 of the optical sheet 20 in the second direction d2 and an end portion of a main body portion 23 (described later) in the second direction d2. The end portion of the unit lenses 21 of the optical sheet 20 in the second direction d2 that is included in the first end portion 2b is referred to as a unit lens end portion 21b. In this embodiment, the end 2a of the covering portion 2, including the first end 2b, is formed by a surface parallel to the thickness direction d3 of the optical sheet 20. The first end 2b is formed by a surface perpendicular to the second direction d2.

[0034] The optical sheet 20 changes the light distribution characteristics of the light emitted from the light-emitting substrate 10 to desired light distribution characteristics. In particular, the optical sheet 20 changes the light distribution characteristics of the light so as to provide desired visual information to a user when the user observes the display device 1 from an expected use direction, which is an expected direction from which the user will observe the display device 1. The expected use direction is, for example, a direction from which the user is expected to frequently view the light emitted from the light-emitting substrate 10. The optical sheet 20 may change the traveling direction of the light emitted from the light-emitting substrate 10. As an example, the optical sheet 20 concentrates the light emitted from the light-emitting substrate 10 in a specific direction. In particular, the illustrated optical sheet 20 concentrates light emitted from the light-emitting substrate 10, which is diffused in a direction perpendicular to the second direction d2, in a specific direction perpendicular to the second direction d2. In other words, the optical sheet 20 changes the traveling direction of light emitted from the light-emitting substrate 10 so that the light appears to be focused in a specific direction when observed from the second direction d2. In this case, the light-focusing direction in which the optical sheet 20 focuses the light emitted from the light-emitting substrate 10 may be the above-mentioned expected use direction. The optical sheet 20 may focus the light emitted from the light-emitting substrate 10 in a direction in which it is expected that users will frequently view the display device 1. The light-focusing direction is the direction in which the luminance is maximized in the luminance distribution of light emitted from the light-emitting substrate 10 and passed through the optical sheet 20. The optical sheet 20 may homogenize the light emitted from the light-emitting substrate 10 so that the light appears uniform when observed from the expected use direction.

[0035] A user of the display device 1 may view the light from the display device 1 through a light-reflecting member. In this case, the light from the display device 1 is emitted toward the light-reflecting member, is reflected by the light-reflecting member, and then reaches the user's eyes. For example, when the display device 1 is used as a head-up display that projects an image onto the windshield of a car, the user views the light from the display device 1 through the windshield. In such a case, the direction of the expected path of the light from the display device 1 to the light-reflecting member can be considered the expected direction of use. In this case, the optical sheet 20 collects the light emitted from the light-emitting substrate 10 in the direction of the expected path of the light from the display device 1 to the light-reflecting member.

[0036] The expected use direction may be, for example, the front direction of the display device 1. In this case, if the expected use direction is the light collection direction, the optical sheet 20 may collect light that is diffused in a direction perpendicular to the second direction d2 emitted from the light emitting substrate 10, toward the front direction of the display device 1. In other words, the light collection direction in which the optical sheet 20 collects light that is diffused in a direction perpendicular to the second direction d2 may be the front direction of the display device 1. The front direction is a direction that is normal to the plate surface of the light emitting substrate 10. The front direction and the normal to the plate surface of the light emitting substrate 10 are directions parallel to the thickness direction d3 of the optical sheet 20. The thickness direction d3 of the optical sheet 20 is the thickness direction of a sheet-like main body portion 23 of the optical sheet 20, which will be described later. The thickness direction d3 of the optical sheet 20 is perpendicular to the first direction d1 and the second direction d2.

[0037] As described below, the light collection direction can be directed toward the front of the display device 1 by overlapping the center C2 in the first direction d1 of each of the multiple unit lenses 21 with the center C1 in the first direction d1 of the light-emitting section 13 of each unit area 10a that constitutes the unit area second direction row 10c.

[0038] Although not shown, the expected use direction may be a direction different from the front direction. Furthermore, the light-collecting direction may be a direction different from the front direction. As an example, the center C2 in the first direction d1 of each of the unit lenses 21 may be offset from the center C1 in the first direction d1 of the light-emitting section 13 of each unit region 10a constituting the unit region second direction row 10c, thereby making the light-collecting direction a direction different from the front direction. In this case, the light-collecting direction in which the optical sheet 20 collects light diffused in a direction perpendicular to the second direction d2 may be a direction perpendicular to the second direction d2 and angled with respect to the front direction (thickness direction d3) of the display device 1. Hereinafter, as an example of the optical sheet 20 of this embodiment, an optical sheet 20 will be described in which the expected use direction is the front direction and the light diffused in a direction perpendicular to the second direction d2 emitted from the light-emitting substrate 10 is collected toward the front direction of the display device 1.

[0039] As shown in FIG. 4 , the optical sheet 20 includes a plurality of unit lenses 21. In the example shown in FIG. 4 , the optical sheet 20 includes a body portion 23 along with the plurality of unit lenses 21. The body portion 23 is sheet-shaped. The plurality of unit lenses 21 are arranged on the surface of the body portion 23. The dashed line indicated by the symbol L1 in FIG. 4 is a virtual line indicating the boundary between the plurality of unit lenses 21 and the body portion 23. In the example shown in FIG. 4 , adjacent unit lenses 21 in the first direction d1 are in contact with each other. In this case, a plane passing through the position where the lens surfaces 21a of adjacent unit lenses 21 are connected and perpendicular to the front direction (thickness direction d3) of the display device 1 can be considered as the boundary L1 between the unit lenses 21 and the body portion 23. Although not shown, as will be described later, a gap may be provided between adjacent unit lenses 21 in the first direction d1. In this case, the plane passing through the position where the surface of the optical sheet 20 formed between adjacent unit lenses 21 and the lens surface 21a of the unit lens 21 are connected and perpendicular to the front direction (thickness direction d3) of the display device 1 can be regarded as the boundary L1 between the unit lens 21 and the main body portion 23.

[0040] The thickness of the optical sheet 20 (the dimension of the optical sheet 20 in the thickness direction d3) is, for example, 10 μm or more and 4000 μm or less. The refractive index of the optical sheet 20 is, for example, 1.4 or more. The refractive index of the optical sheet 20 may be 1.45 or more, or 1.5 or more. The refractive index of the optical sheet 20 may be less than 1.7, less than 1.65, or 1.6 or less. The refractive index of the optical sheet 20 is, for example, 1.4 or more and 1.6 or less. The material of the optical sheet 20 is not particularly limited, but may be, for example, a light-transmitting material made of resin, glass, or the like. Examples of materials for the optical sheet 20 include polyethylene terephthalate, polyolefin, polycarbonate, polyacrylate, polyamide, triacetyl cellulose, and glass. The optical sheet 20 may be formed of, for example, a film mainly composed of polyethylene terephthalate, polyolefin, polycarbonate, polyacrylate, polyamide, or triacetyl cellulose, or glass. As an example, the optical sheet 20 includes different materials. For example, the optical sheet 20 may be formed by disposing the material of the unit lenses 21 on a substrate layer and shaping the material. In this case, the main body 23 of the optical sheet 20 includes the substrate layer. Therefore, the portions constituting the unit lenses 21 of the optical sheet 20 and at least a part of the main body 23 of the optical sheet 20 are made of different materials. The main body 23 and the unit lenses 21 of the optical sheet 20 may be integrally formed from the same material.

[0041] The terms "having optical transparency" and "transparent" mean that the optical sheet 20 has a degree of transparency that allows viewing from one side of the optical sheet 20 to the other side. The optical sheet 20 has a visible light transmittance of, for example, 30% or more, and more preferably 70% or more. The visible light transmittance is specified as the average value of the transmittance at each wavelength when measured using a spectrophotometer (Shimadzu Corporation's "UV-3100PC," compliant with JIS K 0115) within a measurement wavelength range of 380 nm to 780 nm.

[0042] Each unit lens 21 is an element that refracts incident light at its surface, i.e., a lens surface 21a, to change the direction of travel of the light. In this embodiment, each unit lens 21 changes the light distribution characteristics of the light emitted from the light-emitting substrate 10 to a desired light distribution characteristic. In the example shown in Fig. 4, each unit lens 21 condenses the light that is diffused in a direction perpendicular to the second direction d2 emitted from the light-emitting substrate 10 toward the front of the display device 1.

[0043] The plurality of unit lenses 21 are aligned in a first direction d1 and extend in a second direction d2 non-parallel to the first direction d1. In this embodiment, the plurality of unit lenses 21 form a linear array lens.

[0044] In the illustrated example, the unit lenses 21 extend linearly in the second direction d2. In the illustrated example, the first direction d1 and the second direction d2 are perpendicular to each other. Therefore, the multiple unit lenses 21 are arranged in a direction perpendicular to the linear extension direction of the unit lenses 21.

[0045] The plurality of unit lenses 21 are arranged corresponding to the unit regions 10a. In this embodiment, the plurality of unit regions 10a are aligned in the first direction d1 and the second direction d2. A row of the unit regions 10a, formed by aligning the plurality of unit regions 10a in the second direction d2 shown in FIG. 1, is referred to as a unit region second direction row 10c. In this embodiment, when observed from the thickness direction d3, one of the unit lenses 21 corresponds to one of the unit region second direction rows 10c. In this embodiment, each of the plurality of unit lenses 21 corresponds to each of the plurality of unit region second direction rows 10c. The unit lens 21 corresponding to the unit region second direction row 10c means that the unit lens 21 overlaps with the center, in the first direction d1, of the light-emitting section 13 of the unit region 10a constituting the unit region second direction row 10c in the thickness direction d3. In the present embodiment, as shown in Fig. 4, each of the plurality of unit lenses 21 overlaps, in the thickness direction d3, with the center C1 in the first direction d1 of the light-emitting section 13 of the unit region 10a constituting each of the unit region second direction rows 10c. In the example shown in Fig. 4, the center C2 in the first direction d1 of each of the plurality of unit lenses 21 overlaps with the center C1 in the first direction d1 of the light-emitting section 13 of the unit region 10a constituting each of the unit region second direction rows 10c.

[0046] In the example shown in FIG. 3 , as described above, the unit region 10a in which the first light-emitting unit 13R is arranged and the unit region 10a in which the second light-emitting unit 13G is arranged are aligned in the second direction d2 in which the unit lenses 21 extend. In this case, one of the unit lenses 21 overlaps the first light-emitting unit 13R and the second light-emitting unit 13G in the thickness direction d3. In the example shown in FIG. 3 , in particular, the unit region 10a in which the first light-emitting unit 13R is arranged, the unit region 10a in which the second light-emitting unit 13G is arranged, and the unit region 10a in which the third light-emitting unit 13B is arranged are aligned in the second direction d2. In this case, one of the unit lenses 21 overlaps the first light-emitting unit 13R, the second light-emitting unit 13G, and the third light-emitting unit 13B in the thickness direction d3.

[0047] The shape of the unit lenses 21 is appropriately selected depending on how the light distribution characteristics of the light emitted from the light-emitting substrate 10 are desired to be changed by the unit lenses 21. The shape of the unit lenses 21 is not particularly limited as long as the light distribution characteristics of the light emitted from the light-emitting substrate 10 can be changed to the desired light distribution characteristics. In the illustrated example, the unit lenses 21 change the traveling direction of light by refraction at the lens surfaces 21a. In a cross section of the display device 1 perpendicular to the second direction d2, the unit lenses 21 have a shape corresponding to a part of a circle or a part of an ellipse. In the present embodiment, the unit lenses 21 have a shape corresponding to a part of a circle in a cross section perpendicular to the second direction d2. In the example shown in FIG. 4, the unit lenses 21 have a semicircular shape in a cross section perpendicular to the second direction d2. In the present embodiment, the unit lenses 21 have a shape corresponding to a cylinder cut along a plane perpendicular to the bottom surface. In this embodiment, the unit lenses 21 refract the light emitted from the light emitting substrate 10 so that the traveling direction of the light changes when observed from the second direction d2.

[0048] Although not shown, in a cross section of the display device 1 perpendicular to the second direction d2, the unit lenses 21 may have a shape corresponding to a part of a square or a part of an approximately square. The unit lenses 21 may have a shape corresponding to a part of a rectangle or a part of an approximately rectangle. The unit lenses 21 may have a shape corresponding to a shape obtained by cutting a rectangular parallelepiped or an approximately rectangular parallelepiped along a plane perpendicular to the bottom surface. Although not shown, the unit lenses 21 may be aspherical lenses.

[0049] Here, the radius of curvature of the lens surface 21a of each unit lens 21 is defined as r. In this embodiment, the radius of curvature r of the lens surface 21a of each unit lens 21 is determined based on the shape of the lens surface 21a as seen in a cross section perpendicular to the second direction d2 of the unit lens 21. Although not shown, if the shape of the lens surface 21a as seen in a cross section perpendicular to the second direction d2 of the unit lens 21 does not correspond to a portion of a circle, the radius of curvature r may be defined as the radius of curvature r at the vertex P1 of each unit lens 21. The vertex P1 of each unit lens 21 is the point on the lens surface 21a as seen in a cross section perpendicular to the second direction d2 of the unit lens 21 that is farthest from the light-emitting substrate 10. The radius of curvature r of the lens surface 21a of each unit lens 21 is determined in accordance with the pitch p of the light-emitting portions 13 and the width w of the light-emitting portions 13 so that the luminance in the direction in which the display device 1 is viewed is sufficiently high. The radius of curvature r is, for example, not less than 2 μm and not more than 3000 μm.

[0050] The length (width) of each unit lens 21 in the first direction d1 is determined appropriately depending on the radius of curvature r, etc. The length (width) of each unit lens 21 in the first direction d1 is, for example, 10 μm or more and 2000 μm or less. The length of each unit lens 21 in the second direction d2 is determined appropriately depending on the width of the region of the light-emitting substrate 10 where the light-emitting section 13 is provided, etc.

[0051] 3 and 4 , the pitch p2 of the unit lenses 21 in the first direction d1 is defined as the distance from the center C2 of a unit lens 21 in the first direction d1 to the center C2 of the unit lens 21 adjacent to that unit lens 21 in the first direction d1. The pitch p2 of the unit lenses 21 is, for example, 10 μm or more and 2000 μm or less. In this embodiment, the pitch p2 of the unit lenses 21 is equal to the pitch p of the light-emitting sections 13.

[0052] 4 , adjacent unit lenses 21 in the first direction d1 are in contact with each other. Although not shown, a gap may be provided between adjacent unit lenses 21 in the first direction d1. In this case, the width of the gap in the first direction d1 provided between adjacent unit lenses 21 in the first direction d1 is determined appropriately depending on the radius of curvature r, the pitch p2 of the unit lenses 21, etc.

[0053] As described above, the covering unit 2 may include the optical sheet 20, the sealing layer 40, and the adhesive layer 50. In this case, the sealing layer 40 and the adhesive layer 50 may be provided between the light emitting substrate 10 and the optical sheet 20. Although not shown, the covering unit 2 covering the light emitting unit 13 of the light emitting substrate 10 may not include the sealing layer 40 and the adhesive layer 50. In this case, the covering unit 2 may be composed of only the optical sheet 20. In other words, the optical sheet 20 may serve as both the sealing layer 40 and the adhesive layer 50.

[0054] The sealing layer 40 is a layer that covers the surface of the light emitting substrate 10 on which the light emitting units 13 are provided. The sealing layer 40 protects the light emitting units 13 by covering the surface of the light emitting substrate 10 on which the light emitting units 13 are provided. The sealing layer 40 may be formed of a transparent member. The material of the sealing layer 40 is not particularly limited, but may be, for example, a resin or silicone. The refractive index of the sealing layer 40 is, for example, 1.4 or more and less than 1.8. The refractive index of the sealing layer 40 may be 1.4 or more and 1.6 or less. The refractive index of the sealing layer 40 may be equal to the refractive index of the optical sheet 20. The thickness of the portion of the sealing layer 40 that overlaps with the light emitting units 13 in the thickness direction d3 of the optical sheet 20 is, for example, 1 μm or more and 2000 μm or less.

[0055] The adhesive layer 50 is a layer that bonds the sealing layer 40 and the optical sheet 20 together by adhesion. The adhesive layer 50 may be formed of a transparent material. The material of the adhesive layer 50 is not particularly limited, and may be, for example, an optically transparent adhesive sheet (OCA). Although not shown, the adhesive layer 50 may not be provided, and the sealing layer 40 and the optical sheet 20 may be bonded together using the characteristics of the sealing layer 40. The refractive index of the adhesive layer 50 is, for example, 1.4 or more and less than 1.8. The refractive index of the adhesive layer 50 may be 1.4 or more and 1.6 or less. The refractive index of the adhesive layer 50 may be equal to the refractive index of the optical sheet 20. The thickness of the adhesive layer 50 is, for example, 1 μm or more and 2000 μm or less.

[0056] 4, the space between the light emitting substrate 10 and the optical sheet 20 is filled with a sealing layer 40 and an adhesive layer 50. As a result, no air layer is formed between the light emitting substrate 10 and the optical sheet 20. The total thickness of the sealing layer 40 and the adhesive layer 50 at the portions that overlap the light emitting section 13 in the thickness direction d3 of the optical sheet 20 is, for example, 10 μm or more and 4000 μm or less.

[0057] As an example, the position of at least a part of the light-emitting section 13 in the first direction d1 overlaps with the position in the first direction d1 of the unit lens end 21b of the unit lens 21 corresponding to the unit region 10a in which the light-emitting section 13 is arranged. In this embodiment, the position of the entire light-emitting section 13 in the first direction d1 overlaps with the position in the first direction d1 of the unit lens end 21b of the unit lens 21 corresponding to the unit region 10a in which the light-emitting section 13 is arranged. In this embodiment, the position of the vertex P1 of the unit lens 21 in the first direction d1 overlaps with the position in the first direction d1 of the light-emitting section 13 arranged in the unit region 10a corresponding to the unit lens 21.

[0058] FIG. 5 is a cross-sectional view of the display device 1 taken along line V-V in FIG. 3. FIG. 5 particularly illustrates an enlarged view of the periphery of the first end 2b of the display device 1. In FIG. 5 and in FIGS. 6, 9 to 11b, 13a, 14, and 18 described below, only the outline of the light-emitting section 13 is shown, and the structure included in the light-emitting section 13 is omitted. FIG. 5 corresponds to a cross-section of the display device 1 cut along a plane passing through the light-emitting section 13 and parallel to the second direction d2 and the thickness direction d3 of the optical sheet 20. Such a cross-section of the display device 1 passing through the light-emitting section 13 and parallel to the second direction d2 and the thickness direction d3 of the optical sheet 20 is referred to as a first cross-section. FIG. 5 particularly corresponds to a cross-section of the display device 1 passing through the vertex P1 of the unit lens 21.

[0059] As shown in FIG. 5 , in the first cross section, the light-emitting unit 13 has a rectangular shape including a first side 131 extending in the thickness direction d3 of the optical sheet 20 and a second side 132 extending in the second direction d2 and having a length equal to or greater than the length of the first side 131. In the first cross section, the light-emitting unit 13 has a pair of first sides 131 and a pair of second sides 132. In the first cross section, the first side 131 facing the first end 2b is referred to as the end-side first side 131a. In the first cross section, the first side 131 opposite the first side 131 facing the first end 2b is referred to as the opposite-side first side 131b. In the first cross section, the second side 132 facing the lens surface 21a is referred to as the lens-surface-side second side 132a. In the first cross section, the second side 132 facing the light-emitting substrate 10 is referred to as the light-emitting substrate-side second side 132b. The rectangle includes a square. That is, the length of the second side 132 may be equal to the length of the first side 131. The light-emitting unit 13 has a rectangular shape including the first side 131 and the second side 132 in any first cross section. In the present embodiment, the light-emitting unit 13 has the shape of a rectangular parallelepiped as described above. As a result, the light-emitting unit 13 has a rectangular shape including the first side 131 and the second side 132 in any first cross section. In the first cross section, the intersection of the end-side first side 131a and the lens surface-side second side 132a is defined as point P2. In the first cross section, the intersection of the end-side first side 131a and the light-emitting substrate-side second side 132b is defined as point P3. In the first cross section, the intersection of the opposite-side first side 131b and the light-emitting substrate-side second side 132b is defined as point P4.

[0060] When the light-emitting unit 13 has a rectangular shape in the first cross section, this includes cases where the shape of the light-emitting unit 13 in the first cross section can be said to be substantially rectangular. When the shape of the light-emitting unit 13 in the first cross section can be said to be substantially rectangular, this includes, for example, cases where the shape of the light-emitting unit 13 in the first cross section is approximately rectangular. When the shape of the light-emitting unit 13 in the first cross section is approximately rectangular, point P2 can be considered to be the intersection of a line extending from the end-side first side 131a and a line extending from the lens surface-side second side 132a. Point P3 can be considered to be the intersection of a line extending from the end-side first side 131a and a line extending from the light-emitting substrate-side second side 132b. Point P4 can be considered to be the intersection of a line extending from the opposite-side first side 131b and a line extending from the light-emitting substrate-side second side 132b.

[0061] In the example shown in Fig. 5, the end 2a of the covering portion 2 in the second direction d2 appears in the first cross section. The cross-sectional view shown in Fig. 5 shows the display device 1 cut at a cross section passing through the vertex P1 of the unit lens 21. In the example shown in Fig. 5, in the first cross section, the dimension w1 of the end 2a of the covering portion 2 in the thickness direction d3 of the optical sheet 20 is equal to the maximum dimension w2 of the covering portion 2 in the thickness direction d3 of the optical sheet 20.

[0062] As described above, an image is displayed on the display device 1 by the light-emitting unit 13 emitting light. As an example, consider a case where a user views the display device 1 from a viewing direction A1 that forms an angle θ2 with respect to the thickness direction d3 shown in FIG. 5 . In particular, consider a case where the refractive indexes of the optical sheet 20, the sealing layer 40, and the adhesive layer 50 are equal. In particular, a case where a user views the light-emitting unit 13 denoted by reference numeral 13a shown in FIG. 5 will be described. In this case, the light-emitting unit 13 denoted by reference numeral 13a is viewed from the opposite side of the first end 2b in the second direction d2. In this case, in the first cross section, light L10 is emitted from point P2 of the light-emitting unit 13 in a direction that forms an angle θ1 with respect to the thickness direction d3 and in the opposite side of the first end 2b in the second direction d2. The light L10 is refracted by the lens surface 21a and reaches the user's eye. Furthermore, light L2 emitted from point P4 of the light-emitting unit 13 in a direction that forms an angle θ1 with respect to the thickness direction d3 and that is opposite the side where the first end 2b is located in the second direction d2 is refracted by the lens surface 21a before reaching the user's eye. In the example shown in FIG. 5 , light L10 and L2 emitted from the light-emitting unit 13 in a direction that forms an angle θ1 with respect to the thickness direction d3 are refracted by the lens surface 21a in a direction that forms an angle θ2 with respect to the thickness direction d3. This allows a user observing the display device 1 from a viewing direction A1 that forms an angle θ2 with respect to the thickness direction d3 to view light L10 and L2. In this case, if the refractive index of the covering unit 2 (the refractive indexes of the optical sheet 20, the sealing layer 40, and the adhesive layer 50) is defined as a refractive index n, the following equation (13) holds between the refractive index n, the angle θ1, and the angle θ2.

[0063] Light, including light beams L10 and L2, emitted from the opposite first side 131b and the lens surface side second side 132a in a direction forming an angle θ1 with respect to the thickness direction d3 is refracted by the lens surface 21a in a direction forming an angle θ2 with respect to the thickness direction d3 before reaching the user's eyes. As a result, a user observing the display device 1 from the viewing direction A1 sees an image formed by this light. Such an image formed by light that reaches the user's eyes directly without being reflected by the end 2a of the covering portion 2 is called a direct image.

[0064] On the other hand, light emitted from the light-emitting unit 13 may be reflected at the end 2a of the covering unit 2, particularly the first end 2b, before reaching the user's eyes. For example, light L3 shown in FIG. 5 is emitted from point P3 of the light-emitting unit 13 in the first cross section in a direction that forms an angle θ1 with respect to the thickness direction d3 and toward the first end 2b in the second direction d2. Light L3 is reflected at the first end 2b and refracted at the lens surface 21a in a direction that forms an angle θ2 with respect to the thickness direction d3 before reaching the user's eyes. Light L13 shown in FIG. 5 is emitted from point P2 of the light-emitting unit 13 in the first cross section in a direction that forms an angle θ1 with respect to the thickness direction d3 and toward the first end 2b in the second direction d2. Light L13 is reflected at the first end 2b and refracted at the lens surface 21a in a direction that forms an angle θ2 with respect to the thickness direction d3 before reaching the user's eyes.

[0065] Light, including light beams L3 and L13, emitted from the first edge 131a on the end side in a direction that forms an angle θ1 with respect to the thickness direction d3 may be reflected at the first end 2b, refracted at the lens surface 21a in a direction that forms an angle θ2 with respect to the thickness direction d3, and then reach the user's eyes. Therefore, a user observing the display device 1 from the viewing direction A1 may see an image formed by this light. Such an image formed by light that is reflected at the end 2a of the covering portion 2 and reaches the user's eyes is called a double image.

[0066] If the brightness of the light emitted from the light-emitting unit 13 and reflected at the end 2 a of the covering unit 2 to reach the user's eyes is high, the reflected light may interfere with the user's visibility of the display device 1. In particular, if the brightness of the above-mentioned double image is high, the double image may interfere with the user's visibility of the direct image. Therefore, from the perspective of ensuring that the user can easily view the direct image, it is preferable to reduce the brightness of the light reflected at the end 2 a of the covering unit 2 to reach the user's eyes. In particular, it is preferable to reduce the ratio of the brightness of the light reflected at the end 2 a of the covering unit 2 to reach the user's eyes directly without being reflected at the end 2 a of the covering unit 2. In particular, it is preferable to reduce the ratio of the brightness of the double image to the brightness of the direct image. The brightness of the double image is the maximum brightness of the light that forms the double image. The brightness of the direct image is the maximum brightness of the light that forms the direct image.

[0067] In particular, the dimension of the first end 2b of the end 2a in the thickness direction d3 tends to be large by the amount corresponding to the unit lens end 21b. Therefore, it is preferable to reduce the brightness of the light that is reflected at the first end 2b and reaches the user's eyes. In particular, it is preferable to reduce the brightness of the double image formed by the light that is reflected at the first end 2b and reaches the user's eyes.

[0068] In particular, when the angle θ2 between the viewing direction A1 and the thickness direction d3 is large, the brightness of light that reaches the user's eyes after being reflected at the first end 2b is likely to be high. Therefore, even if the angle θ2 is large within the range expected in normal usage of the display device 1, it is preferable to be able to reduce the brightness of light that reaches the user's eyes after being reflected at the first end 2b. As an example, if the display device 1 is a device whose orientation can be freely adjusted by the user, such as a smartphone or tablet device, the angle θ2 expected in normal usage is considered to be 30° or less. Therefore, when the angle θ2 is 30° or less, it is preferable to be able to reduce the brightness of light that reaches the user's eyes after being reflected at the first end 2b.

[0069] The present inventors have conducted extensive research into a display device 1 that can reduce the brightness of light that is reflected at the first end 2b and reaches the user's eyes, thereby ensuring that the user can easily view the direct image. As a result, the present inventors have found that the brightness of the double image can be sufficiently ensured by suppressing the brightness of the double image to less than 50% of the brightness of the direct image. Furthermore, the present inventors have found that when the angle θ2 between the viewing direction A1 and the thickness direction d3 is 30° or less, the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image if any one of the following conditions is met: the refractive index n of the covering portion 2 is 1.4 or greater but less than 1.5 and the following formula (1) is satisfied; the refractive index n of the covering portion 2 is 1.5 or greater but less than 1.6 and the following formula (2) is satisfied; or the refractive index n of the covering portion 2 is 1.6 or greater and the following formula (3) is satisfied. H1 is the length of the first side 131 in the first cross section. D1 is the distance in the second direction d2 in the first cross section between the end 2a of the cover 2 and the light emitting unit 13. Y1 is the distance between the lens surface 21a of the unit lens 21 and the light emitting unit 13 in the first cross section.

[0070] As described above, the refractive index of the covering portion 2 made of a general material is 1.4 or higher. In particular, the refractive index of the optical sheet 20, sealing layer 40, and adhesive layer 50 made of a general material is 1.4 or higher. Under the conditions that the brightness of the double image can be reduced to less than 50% of the brightness of the direct image, the optical sheet 20 using the covering portion 2 made of a general material can ensure sufficient visibility of the direct image.

[0071] This section explains a method for deriving the conditions, including formulas (1) to (3), for suppressing the brightness of the double image to less than 50% of the brightness of the direct image when the angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 30° or less. The inventors conducted a simulation test to determine the above conditions.

[0072] In the simulation test, a display device 1 was simulated, which included one unit region 10a of the semiconductor layer 11, one light-emitting section 13 arranged in the unit region 10a, and a covering section 2 including one unit lens 21 corresponding to the unit region 10a, as shown in Fig. 6. In Fig. 6 and Figs. 9 to 11a described below, only the outline of the covering section 2 is shown, and the structure included in the covering section 2 is not shown.

[0073] In the display device 1 used in the simulation test, the shape of the unit lens 21 was a rectangular parallelepiped extending in the second direction d2. In the display device 1 used in the simulation test, the shape of the light-emitting unit 13 was a cube having a pair of faces parallel to the first direction d1 and the second direction d2, a pair of faces parallel to the first direction d1 and the thickness direction d3, and a pair of faces parallel to the second direction d2 and the thickness direction d3. As a result, in the first cross section, the length of the second side 132 was equal to the length H1 of the first side 131. In the display device 1 used in the simulation test, the center C2 of the unit lens 21 in the first direction d1 overlapped with the center C1 of the light-emitting unit 13 of the unit region 10a in the first direction d1. More specifically, the angular light distribution of the light emitted from the first side 131 of the light-emitting unit 13 used in the simulation test was set to be the same as the angular light distribution of the light emitted from the second side 132.

[0074] In the simulation test, the length H1 of the first side 131 and the length of the second side in the first cross section were fixed by fixing the length of one side of the cubic light-emitting unit 13. Then, the refractive index n, the distance D1, and the distance Y1 were changed to determine the ratio of the luminance of the double image to the luminance of the direct image when the angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 30°.

[0075] 7a to 7c are graphs showing the ratio of the brightness of the double image to the brightness of the direct image when the angle θ2 between the viewing direction A1 and the thickness direction d3 is 30° and the refractive index n is fixed and the distance D1 and distance Y1 are changed. Figure 7a shows the ratio when the refractive index n is fixed at 1.4. Figure 7b shows the ratio when the refractive index n is fixed at 1.5. Figure 7c shows the ratio when the refractive index n is fixed at 1.6. Each of the broken lines in Figures 7a to 7c shows the change in the ratio of the brightness of the double image to the brightness of the direct image when the distance Y1 is fixed and the distance D1 is changed. For example, the broken line labeled "1.00H1" in Figure 7a shows the change in the ratio of the brightness of the double image to the brightness of the direct image when the distance Y1 is fixed at 1.00 times the length H1 of the first side 131 in the first cross section and the distance D1 is changed. The horizontal axis in Figures 7a to 7c represents the distance D1. For example, the "0.5H1" on the horizontal axis in Figure 7a means that the distance D1 is 0.5 times the length H1 of the first side 131 in the first cross section. The vertical axes in Figures 7a to 7c represent the ratio of the brightness of the double image to the brightness of the direct image, expressed as a percentage. The dashed line labeled L7 in Figures 7a to 7c indicates the position where the ratio of the brightness of the double image to the brightness of the direct image is 50%.

[0076] From the simulation test results shown in Figures 7a to 7c, it can be seen that the smaller the distance D1, the easier it is to reduce the ratio of the brightness of the double image to the brightness of the direct image. From the simulation test results shown in Figures 7a to 7c, it can be seen that the larger the distance Y1, the easier it is to reduce the ratio of the brightness of the double image to the brightness of the direct image. From the simulation test results shown in Figures 7a to 7c, it can be seen that the larger the refractive index n, the easier it is to reduce the ratio of the brightness of the double image to the brightness of the direct image.

[0077] Figure 8a shows the relationship between the distance D1 and the distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% when the refractive index n is 1.4, as obtained from the results of the simulation test shown in Figure 7a. Figure 8b shows the relationship between the distance D1 and the distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% when the refractive index n is 1.5, as obtained from the results of the simulation test shown in Figure 7b. Figure 8c shows the relationship between the distance D1 and the distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% when the refractive index n is 1.6, as obtained from the results of the simulation test shown in Figure 7c. The horizontal axis in Figures 8a to 8c indicates the distance D1. For example, the notation "1.00H1" on the horizontal axis in Figure 8a means that the distance D1 is 1.00 times the length H1 of the first side 131 in the first cross section. The vertical axis in Figures 8a to 8c indicates the distance Y1. For example, the indication "0.50H1" on the vertical axis in FIG. 8a means that the distance Y1 is 0.50 times the length H1 of the first side 131 in the first cross section.

[0078] 8a to 8c, it can be seen that the plots representing the correspondence relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% are roughly aligned on a single straight line (dashed line marked with symbol L8). From this, it can be seen that the correspondence relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% can be approximated by a linear function. Furthermore, it is clear that the straight line (dashed line marked with symbol L8) representing the correspondence relationship between distance D1 and distance Y1 does not pass through the origin of the graph. From this, it can be seen that the correspondence relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% can be approximated by a linear function with an intercept that is not zero.

[0079] In Fig. 8a, the plot showing the correspondence relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% was approximated to a linear function by the least squares method, resulting in the following equation (14): In Fig. 8b, the plot showing the correspondence relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% was approximated to a linear function by the least squares method, resulting in the following equation (15): In Fig. 8c, the plot showing the correspondence relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% was approximated to a linear function by the least squares method, resulting in the following equation (16):

[0080] As described above, the smaller the distance D1, the smaller the ratio of the brightness of the double image to the brightness of the direct image. Furthermore, the larger the distance Y1, the smaller the ratio of the brightness of the double image to the brightness of the direct image. Therefore, from equation (14), equation (1) is derived as the condition under which the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image when the refractive index n of the covering portion 2 is 1.4. From equation (15), equation (2) is derived as the condition under which the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image when the refractive index n of the covering portion 2 is 1.5. From equation (16), equation (3) is derived as the condition under which the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image when the refractive index n of the covering portion 2 is 1.6. Furthermore, as described above, the larger the refractive index n, the smaller the ratio of the brightness of the double image to the brightness of the direct image. Therefore, if the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image when the refractive index n of the covering portion 2 is 1.4, then the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image even when the refractive index n is 1.4 or more and less than 1.5. If the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image when the refractive index n of the covering portion 2 is 1.5, then the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image even when the refractive index n is 1.5 or more and less than 1.6. If the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image when the refractive index n of the covering portion 2 is 1.6, then the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image even when the refractive index n is 1.6 or more.

[0081] From the above, when the angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 30° or less, the condition for suppressing the brightness of the double image to less than 50% of the brightness of the direct image is derived as follows: the refractive index n of the covering portion 2 is 1.4 or more and less than 1.5 and the following formula (1) is satisfied; the refractive index n of the covering portion 2 is 1.5 or more and less than 1.6 and the following formula (2) is satisfied; or the refractive index n of the covering portion 2 is 1.6 or more and the following formula (3) is satisfied. Based on this, the present inventors have completed the invention according to this embodiment.

[0082] The theoretical basis for the derived conditions will now be considered. Let us consider a case where the shape of the light-emitting unit 13 is a cube and the light-emitting unit 13 has a square shape in the first cross section as shown in Fig. 9. That is, let us consider a case where the length of the second side 132 is equal to the length H1 of the first side 131.

[0083] The intersection of the lens surface 21a and the first end 2b is designated as intersection P5. As shown in FIG. 9, when the distances D1 and Y1 are D11 and Y11, respectively, the brightness of the double image is 50% of the brightness of the direct image. As shown in FIG. 9, when the light-emitting unit 13 is positioned so that the brightness of the double image is 50% of the brightness of the direct image, point P6 is designated as the point on the contour of the light-emitting unit 13 in the first cross section that passes through intersection P5 and overlaps with a line that forms an angle θ1 with respect to the thickness direction d3. Light emitted from point P6 in a direction that forms an angle θ1 with respect to the thickness direction d3 and toward the side where the first end 2b is located in the second direction d2 is designated as light L4. When the light-emitting unit 13 is positioned so that the brightness of the double image is 50% of the brightness of the direct image, light L4 passes through intersection P5. In this case, light L4 is reflected at intersection P5 and refracted in a direction that forms an angle θ2 with respect to the thickness direction d3. In the example shown in Figure 9, point P6 is located on the lens surface side second edge 132a. Although not shown, point P6 may also be located on the end side first edge 131a. Although not shown, point P6 may also coincide with point P2. In this case, the double image is formed by light emitted from the end side first edge 131a and a portion of the lens surface side second edge 132a located between points P6 and P2. In contrast, the direct image is formed by light emitted from the opposite side first edge 131b and the lens surface side second edge 132a.

[0084] Consider the case where the light-emitting unit 13 is located at the dashed-dotted line indicated by reference numeral 13c in FIG. 9 , thereby causing the distance D1 to be greater than the distance D11. When the light-emitting unit 13 is located at the dashed-dotted line indicated by reference numeral 13c, the position of point P6 on the light-emitting unit 13 is designated as point P61. In this case, light L4 emitted from point P61 in a direction forming an angle θ1 with respect to the thickness direction d3 and toward the first end 2b in the second direction d2 is designated as light L42. In this case, light L42 is not reflected at the first end 2b and does not form a double image. Therefore, when the distance D1 is greater than the distance D11, the brightness of the double image is smaller than when the distance D1 is the same as the distance D11. Therefore, in the simulation test, it was believed that the ratio of the brightness of the double image to the brightness of the direct image could be reduced as the distance D1 was reduced.

[0085] Next, consider the case where the lens surface 21a is located at the position indicated by the dashed-dotted line 21c in FIG. 9, thereby causing the distance Y1 to be smaller than the distance Y11. In this case, light L4 is emitted from point P6 of the light-emitting unit 13 in a direction forming an angle θ1 with respect to the thickness direction d3 and toward the first end 2b in the second direction d2, and is designated as light L43. In this case, light L43 is not reflected at the first end 2b and does not form a double image. Therefore, when the distance Y1 is smaller than the distance Y11, the brightness of the double image is smaller than when the distance Y1 is the same as the distance Y11. Therefore, in the simulation test, it was believed that the ratio of the brightness of the double image to the brightness of the direct image could be reduced as the distance Y1 was increased.

[0086] From the above, it is thought that the brightness of the double image can be reduced theoretically by increasing the distance D1 or decreasing the distance Y1.

[0087] Next, consider the case where light L5 is emitted from point P6 of the light-emitting unit 13 in a direction that forms an angle θ11 with respect to the thickness direction d3 and toward the first end 2b in the second direction d2, passing through intersection P5, when the refractive index n of the coating 2 is n1, as shown in FIG. 10 . In this case, light L5 is reflected at intersection P5 and refracted in a direction that forms an angle θ21 with respect to the thickness direction d3. The angle θ21 is determined according to Snell's law based on the refractive index n1 and the angle θ11. Let us consider the case where the refractive index n of the coating 2 shown in FIG. 10 is changed to n2, which is larger than n1. In this case, light L5 is reflected at intersection P5 and refracted in a direction that forms an angle θ22 with respect to the thickness direction d3. The dashed line labeled L6 in FIG. 10 represents the path of light L5 after passing through intersection P5 when the refractive index n of the coating 2 is changed to n2. The angle θ22 is determined according to Snell's law based on the refractive index n2 and the angle θ11. Since the refractive index n2 is greater than the refractive index n1, the angle θ22 is greater than the angle θ21.

[0088] As can be seen from Figure 10, as the refractive index n of the covering portion 2 increases, the angle of the traveling direction of light reflected at the first end 2b and refracted at the lens surface 21a relative to the thickness direction d3 increases. Therefore, as the refractive index n of the covering portion 2 increases, it becomes more difficult for light reflected at the first end 2b and refracted at the lens surface 21a to reach the eyes of a user viewing the display device 1 from a direction close to the front direction (thickness direction d3) of the display device 1. For this reason, it is believed that in simulation tests, the ratio of the brightness of the double image to the brightness of the direct image could be reduced as the refractive index n increased. Similarly, when the refractive index of some of the components included in the covering portion 2 is increased, it becomes more difficult for light reflected at the first end 2b and refracted at the lens surface 21a to reach the eyes of a user viewing the display device 1 from a direction close to the front direction (thickness direction d3) of the display device 1. For example, even if the refractive index of at least one of the optical sheet 20, the sealing layer 40, and the adhesive layer 50 is increased, the light reflected at the first end 2b and refracted at the lens surface 21a becomes less likely to reach the user's eyes.

[0089] From the above, it can be seen that theoretically, the condition under which the brightness of the double image is 50% of the brightness of the direct image can be expressed by a function with the distances D1 and Y1 as variables. Furthermore, it can be seen that to reduce the brightness of the double image to less than 50% of the brightness of the direct image, it is sufficient to increase the distance D1 or decrease the distance Y1 from a state in which the brightness of the double image is 50% of the brightness of the direct image. However, in reality, not all of the light emitted from the light-emitting unit 13 is necessarily reflected at the end 2a to form a double image. According to Fresnel's equation, a portion of the light emitted from the light-emitting unit 13 passes through the end 2a without being reflected. Therefore, compared to the hypothetical display device 1 assumed when considering the theoretical basis of the derived conditions, the ratio of the brightness of the double image to the brightness of the direct image is smaller in the actual display device 1. It can be said that the conditions derived from the above simulation tests were derived taking into account such realistic circumstances.

[0090] The above-described simulation tests were conducted to derive the conditions for suppressing the brightness of the double image to less than 50% of the brightness of the direct image, and the theoretical basis for these conditions was based on the assumption that the light-emitting unit 13 has a cubic shape and a square shape in the first cross section. This section explains how these conditions can also be applied to cases where the light-emitting unit 13 has a rectangular shape other than a square in the first cross section, as shown in FIG. 11a. Specifically, consider a case where the length of the second side 132 is greater than the length H1 of the first side 131. In this case, the length of the lens surface-side second side 132a is greater than when the light-emitting unit 13 has a square shape in the first cross section with the same length H1 of the first side 131 (the square indicated by the dashed line labeled 13d in FIG. 11a). Therefore, under the condition that the distance D1 and the distance Y1 are constant, when the length of the second side 132 of the light-emitting unit 13 is greater than the length H1 of the first side 131 in the first cross section, the surface area of ​​the light-emitting unit 13 that emits light that forms a direct image is larger than when the light-emitting unit 13 has a square shape with the first side 131 having the same length H1. As a result, the ratio of the brightness of the double image to the brightness of the direct image is smaller. Therefore, when the light-emitting unit 13 has a square shape in the first cross section, if the derived condition is satisfied and the brightness of the double image is less than 50% of the brightness of the direct image, then even when the length of the second side 132 is greater than the length H1 of the first side 131, the derived condition is satisfied and the brightness of the double image is less than 50% of the brightness of the direct image. Therefore, when the length of the second side 132 is equal to or greater than the length of the first side 131, the derived condition is satisfied and the brightness of the double image is less than 50% of the brightness of the direct image. When the light emitting section 13 has a rectangular shape rather than a square shape in the first cross section, the shape of the light emitting section 13 is, for example, a rectangular parallelepiped rather than a cube.

[0091] Next, we will explain the theoretical basis for the fact that, particularly under certain assumptions, the condition under which the brightness of the double image is 50% of the brightness of the direct image can be expressed by a linear function with the distance D1 and the distance Y1 as variables. Figure 11b is a diagram for explaining the theoretical basis for the condition under which the brightness of the double image is 50% of the brightness of the direct image. In the example shown in Figure 11b, the light-emitting unit 13 is positioned in a direction that forms an angle θ1 with the thickness direction d3 from point P2, and so that light L13 emitted toward the side where the first end 2b is located in the second direction d2 passes through the intersection point P5. In other words, in the example shown in Figure 11b, the above-mentioned point P6 coincides with point P2. We will consider a case where the brightness of the double image is 50% of the brightness of the direct image when the light-emitting unit 13 is positioned as shown in Figure 11b. We will explain the fact that, at least in such a case, the condition under which the brightness of the double image is 50% of the brightness of the direct image can be expressed by a linear function with the distance D1 and the distance Y1 as variables.

[0092] When the light-emitting unit 13 is positioned so that light L13 emitted from point P2 in a direction forming an angle θ1 with respect to the thickness direction d3 passes through intersection point P5, light L13 is reflected at intersection point P5 and refracted in a direction forming an angle θ2 with respect to the thickness direction d3. At this time, a double image is formed by light emitted from the end-side first side 131a. In contrast, a direct image is formed by light emitted from the opposite-side first side 131b and the lens-surface-side second side 132a. When the light-emitting unit 13 is positioned so that light L13 passes through intersection point P5, the following equation (32) holds between angle θ1, distance D1, and distance Y1.

[0093] From the above-mentioned equations (13) and (32), the following equation (33) is obtained.

[0094] From equation (33), assuming that the brightness of the double image is 50% of the brightness of the direct image when light-emitting unit 13 is positioned as shown in Figure 11b, it can be seen that the condition under which the brightness of the double image is 50% of the brightness of the direct image can be expressed by a linear function with distance D1 and distance Y1 as variables. In particular, it can be seen that the condition under which the brightness of the double image is 50% of the brightness of the direct image can be expressed by a proportional equation with a coefficient of 1 / tan(a sin(sin θ2 / n)).

[0095] As described above, the brightness of the double image can be reduced by increasing the distance D1 or decreasing the distance Y1. Considering that the brightness of the double image is 50% of the brightness of the direct image when the formula (33) is satisfied, it is considered that the brightness of the double image will be less than 50% of the brightness of the direct image when the following formula (34) is satisfied.

[0096] As described above, assuming that the brightness of the double image is 50% of the brightness of the direct image when the light-emitting unit 13 is positioned as shown in Figure 11b, equation (34) can be theoretically derived as the condition under which the brightness of the double image is less than 50% of the brightness of the direct image. Furthermore, if equation (34) expresses the condition under which the brightness of the double image is less than 50% of the brightness of the direct image when the light-emitting unit 13 is positioned as shown in Figure 11b, it is believed that equation (34) can also express the condition under which the brightness of the double image is less than 50% of the brightness of the direct image when the light-emitting unit 13 is positioned as shown in Figure 11b and the brightness of the double image is 50% or more of the brightness of the direct image. Furthermore, substituting 30° for θ2 and 1.4 for n in "tan(a sin(sin θ2 / n))" in equation (34) yields a value relatively close to "2.600" shown in equation (1) above. Substituting 30° for θ2 and 1.5 for n in "tan(a sin(sin θ2 / n))" in equation (34) yields a value relatively close to "2.822" shown in equation (2) above. Substituting 30° for θ2 and 1.6 for n in "tan(a sin(sin θ2 / n))" in equation (34) yields a value relatively close to "3.049" shown in equation (3) above.

[0097] As mentioned above, by making certain assumptions, conditions similar to those derived from simulation tests can be derived as conditions for suppressing the luminance of the double image to less than 50% of the luminance of the direct image. However, as mentioned above, the conditions derived from simulation tests can be said to be conditions derived by taking into consideration more realistic circumstances than the theoretically derived conditions.

[0098] The display device 1 of this embodiment includes a light-emitting substrate 10 having a semiconductor layer 11 divided into a plurality of unit regions 10a and light-emitting sections 13 arranged in the plurality of unit regions 10a. The display device 1 of this embodiment also includes an optical sheet 20 arranged opposite the light-emitting substrate 10 and a covering section 2 covering the light-emitting sections 13. The optical sheet 20 has a plurality of unit lenses 21 aligned in a first direction d1 and extending in a second direction d2 non-parallel to the first direction d1. The plurality of unit regions 10a are aligned in the first direction d1 and the second direction d2. In a first cross section passing through the light-emitting section 13 and parallel to the second direction d2 and the thickness direction of the optical sheet 20, the light-emitting section 13 has a rectangular shape including a first side 131 extending in the thickness direction d3 of the optical sheet 20 and a second side 132 extending in the second direction d2 and having a length equal to or greater than the length of the first side 131. In the first cross section, the length of the first side 131 is defined as H1, the distance in the second direction d2 between the end 2a of the covering portion 2 and the light-emitting portion 13 is defined as D1, and the distance between the lens surface 21a of the unit lens 21 and the light-emitting portion 13 is defined as Y1. In this case, one of the following is true: the refractive index n of the covering portion 2 is 1.4 or more but less than 1.5 and the following formula (1) is satisfied; the refractive index n of the covering portion 2 is 1.5 or more but less than 1.6 and the following formula (2) is satisfied; or the refractive index n of the covering portion 2 is 1.6 or more but less than 1.6 and the following formula (3) is satisfied.

[0099] By satisfying the above conditions, the brightness of light that is reflected at the end 2a of the covering portion 2 and reaches the user's eyes can be reduced, ensuring that the user can easily view the direct image. In particular, the ratio of the brightness of the double image to the brightness of the direct image can be made less than 50%. In particular, taking into account the circumstances of the actual display device 1 described above, the ratio of the brightness of the double image to the brightness of the direct image can be made less than 50%. In particular, when the assumed angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 30° or less, the ratio of the brightness of the double image to the brightness of the direct image can be made less than 50%.

[0100] In the cross section of the display device 1 of the present embodiment perpendicular to the second direction d2, the unit lenses 21 may have a shape corresponding to a part of a circle or a part of an ellipse. Such unit lenses 21 can refract light emitted from the light-emitting substrate 10 so that the traveling direction of the light changes when observed from the second direction d2. The display device 1 of the present embodiment can use such unit lenses 21 to sufficiently reduce the brightness of light that is reflected at the first end 2 b and reaches the user's eyes.

[0101] 4 and 5 , the maximum distance between the lens surface 21a of each unit lens 21 and the light-emitting unit 13 in the thickness direction d3 is defined as distance Y3. In the display device 1 of the present embodiment, the following conditions may be satisfied between the distance Y3 and the length H1 and distance D1 in any first cross section: the refractive index n of the covering portion 2 is 1.4 or greater but less than 1.5 and the following formula (17) is satisfied; the refractive index n of the covering portion 2 is 1.5 or greater but less than 1.6 and the following formula (18) is satisfied; or the refractive index n of the covering portion 2 is 1.6 or greater but the following formula (19) is satisfied. By satisfying the above conditions, when the angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is assumed to be 30° or less, the brightness of the light that is reflected at the end 2a of the covering portion 2 and reaches the user's eyes is reduced, thereby ensuring a more stable and easy-to-view direct image for the user.

[0102] Next, a description will be given of an example of a method for manufacturing the display device 1. First, the light emitting substrate 10 is prepared. Then, the sealing layer 40 is formed so as to cover the surface of the light emitting substrate 10 on which the light emitting section 13 is provided.

[0103] Next, the optical sheet 20 is manufactured. The optical sheet 20 can be manufactured, for example, by the following method. First, as shown in FIG. 12a, a layer 70 is formed on a substrate layer 60. The layer 70 is a layer of material for the unit lenses 21. The layer 70 of material for the unit lenses 21 is, for example, a resin layer. In this case, the layer 70 of material for the unit lenses 21 may be an acrylic resin. Next, as shown in FIG. 12b, the layer 70 formed on the substrate layer 60 is shaped to form a lens surface 21a on the substrate layer 60. In this way, the optical sheet 20 can be formed. In this case, the optical sheet 20 is a laminate of the substrate layer 60 and the layer 70.

[0104] Next, the sealing layer 40 and the optical sheet 20 are bonded together via an adhesive layer 50. In this step, the surface of the optical sheet 20 opposite the lens surface 21a shown in Fig. 12b is bonded to the surface of the sealing layer 40 via the adhesive layer 50. In this way, the display device 1 shown in Figs. 1 to 5 is manufactured.

[0105] According to the above-described manufacturing method, a display device 1 is manufactured that includes an optical sheet 20 that includes, in particular, a base layer 60 and a layer 70. The optical sheet 20 does not have to include the base layer 60. In this case, the optical sheet 20 may be made of the layer 70. In a display device 1 that includes such an optical sheet 20, the above-described distance Y1 is easily reduced because the optical sheet 20 does not include the base layer 60. Therefore, in such a display device 1, the above-described formulas (1)-(3) and formulas (17)-(19) are easily satisfied. As described above, according to such a display device 1, the brightness of light that is reflected at the end 2a of the covering portion 2 and reaches the user's eyes can be further reduced.

[0106] A display 100 including a plurality of display devices 1 may be manufactured using the display device 1 of this embodiment. FIG. 12c is a diagram showing a display 100 including a plurality of display devices 1 of this embodiment. As shown in FIG. 12c , in a display 100 including a plurality of display devices 1, the plurality of display devices 1 may be arranged so as to be in contact with each other. In FIG. 12c and FIG. 19 described later, only the outer shape of the display device 1 is shown, and the structure included in the display device 1 is not shown. In this case, in the display 100, the ends 2a of the plurality of display devices 1 are in contact with each other. In particular, the plurality of display devices 1 may be arranged so as to be in contact with each other at least in the second direction d2. In this case, in the display 100, the first ends 2b of the plurality of display devices 1 are in contact with each other. In this case, the first ends 2b of the display devices 1 may be arranged at a position away from the end of the display 100 in the second direction d2. In particular, the first ends 2b of the display devices 1 may be arranged near the center of the display 100 in the second direction d2. According to the display device 1 of the present embodiment, even when the display device 1 is incorporated into the display 100, the brightness of light that is reflected at the first end 2b and reaches the user's eyes can be reduced. This ensures that the direct image is easily visible throughout the entire display 100. In particular, it becomes easier to prevent the joints of the display 100, where the first ends 2b of the multiple display devices 1 meet, from being visible due to light reflection at the first ends 2b.

[0107] Various modifications can be made to the above-described embodiment. An example of a modification will be described below with reference to the drawings. In the following description and the drawings used in the following description, parts that can be configured similarly to the above-described specific example will be designated by the same reference numerals as those used for the corresponding parts in the above-described specific example, and duplicated explanations may be omitted. Furthermore, if it is clear that the effects obtained in the above-described embodiment can also be obtained in the modified example, the explanations may be omitted.

[0108] (Variation 1) In the above-described embodiment, the display device 1 has been described in which, in the first cross section, the dimension w1 of the end 2a of the covering portion 2 in the thickness direction d3 of the optical sheet 20 is equal to the maximum dimension w2 of the covering portion 2 in the thickness direction d3 of the optical sheet 20. However, the configuration of the optical sheet 20 is not limited to this. FIG. 13a is an enlarged perspective view showing the periphery of the first end 2b of one unit lens 21 in the display device 1 of Variation 1. FIG. 13b is a cross-sectional view of the display device 1 having the unit lens 21 shown in FIG. 13a, cut so that the unit lens 21 is cut in a cross section taken along line XIII-XIII in FIG. 13a. FIG. 13b corresponds to a cross section of the display device 1 cut along a plane passing through the light-emitting portion 13, which is parallel to the second direction d2 and the thickness direction d3 of the optical sheet 20.

[0109] In the example shown in FIG. 13b, in the first cross section, the dimension w1 of the end 2a of the covering portion 2 in the thickness direction d3 of the optical sheet 20 is smaller than the maximum dimension w2 of the covering portion 2 in the thickness direction d3 of the optical sheet 20. This provides the following effect. It may be necessary to increase the maximum dimension w2 of the covering portion 2 in the thickness direction d3 of the optical sheet 20. For example, depending on the optical function required of the unit lenses 21, it may be necessary to increase the dimension w3 of the unit lenses 21 in the thickness direction d3 of the optical sheet 20, as shown in FIG. 13a. In this case, increasing the dimension w3 increases the maximum dimension w2. Thus, even when it is necessary to increase the maximum value w2, reducing the dimension w1 of the end 2a of the covering portion 2 can reduce the brightness of light that is reflected by the end 2a of the covering portion 2 and reaches the user's eyes. In particular, even when it is necessary to increase the maximum value w2, reducing the dimension w1 can reduce the distance Y1. As a result, even when the maximum value w2 needs to be increased, the above-described formulas (1) to (3) and formulas (17) to (19) are more likely to be satisfied.

[0110] 13b, in the first cross section, the dimension w4 of the end 21b of the unit lens in the thickness direction d3 of the optical sheet 20 is smaller than the maximum dimension w5 of the unit lens 21 in the thickness direction d3 of the optical sheet 20. This allows the dimension w1 to be smaller than the maximum dimension w2.

[0111] In the example shown in Fig. 13b, the covering portion 2 has an end region 2c that extends in the second direction d2 and includes the end 2a of the covering portion 2. In the example shown in Fig. 13b, the covering portion 2 has the end region 2c and a main body region 2d, which is the region other than the end region 2c. The covering portion 2 covers the light-emitting portion 13 in the main body region 2d. In the first cross section, the dimension w6 of the covering portion 2 in the thickness direction d3 of the optical sheet 20 gradually decreases within the end region 2c along the second direction d2 toward the end 2a of the covering portion 2. This allows the dimension w1 to be smaller than the maximum value w2.

[0112] 13b, in the first cross section, the dimension w7 of the unit lenses 21 in the thickness direction d3 of the optical sheet 20 gradually decreases in the end region 2c along the second direction d2 toward the end 2a of the covering portion 2. As a result, the dimension w6 gradually decreases in the end region 2c along the second direction d2 toward the end 2a of the covering portion 2.

[0113] In the example shown in Figure 13b, in the edge region 2c, the unit lens 21 has an inclined surface 21c connecting the lens surface 21a and the unit lens edge 21b. In the first cross section shown in Figure 13b, the angle θ3 that the inclined surface 21c makes with the thickness direction d3 is greater than 0°. By having the unit lens 21 have the inclined surface 21c in the edge region 2c, the dimension w1 can be made smaller than the maximum value w2. Furthermore, by having the unit lens 21 have the inclined surface 21c in the edge region 2c, light reflected at the portion of the surface of the unit lens 21 located in the edge region 2c is less likely to reach the user's eyes.

[0114] 13a, the portion of the unit lens 21 located in the main body region 2d has a shape equivalent to a cylinder cut along a plane perpendicular to its bottom. The portion of the unit lens 21 located in the edge region 2c has a shape equivalent to a truncated cone cut along a plane perpendicular to its bottom. As a result, the unit lens 21 has an inclined surface 21c in the edge region 2c.

[0115] (Modification 2) The unit lenses 21 may be linear Fresnel lenses. Fig. 14 is a cross-sectional view of the display device 1 of Modification 2 taken along a plane perpendicular to the second direction d2. In the display device 1 shown in Fig. 14, the unit lenses 21 are linear Fresnel lenses.

[0116] 14 , the lens surface 21 a of each unit lens 21 has a plurality of Fresnel lens surfaces 211 and a plurality of rise surfaces 212 connecting adjacent Fresnel lens surfaces 211. Each of the plurality of Fresnel lens surfaces 211 and the plurality of rise surfaces 212 extends along the second direction d2. The plurality of Fresnel lens surfaces 211 correspond to a plurality of lens surfaces obtained by dividing a continuous lens surface of a virtual lens into a plurality of portions along a plane perpendicular to the thickness direction (optical axis direction) of the lens. By having the lens surface 21 a of each unit lens 21 have such a plurality of Fresnel lens surfaces 211, the unit lens 21 can exhibit the same optical effect as the virtual lens.

[0117] In the example shown in Fig. 14, the multiple Fresnel lens surfaces 211 correspond to multiple lens surfaces obtained by dividing the lens surface of a virtual lens having a continuous lens surface corresponding to the shape of a portion of the side surface of a cylinder into multiple parts along a plane perpendicular to the thickness direction of the lens. In the example shown in Fig. 14, the lens surface 21a of each unit lens 21 has a curved surface 213 at the center in the first direction d1 that protrudes in a direction away from the light-emitting substrate 10. The curved surface 213 has a shape corresponding to the shape of a portion of the side surface of a cylinder. The unit lens 21 shown in Fig. 14 can exhibit the same optical effect as a lens having a continuous lens surface corresponding to the shape of a portion of the side surface of a cylinder.

[0118] By making the unit lenses 21 linear Fresnel lenses, the maximum dimension w8 of the unit lens end 21b in the thickness direction d3 of the optical sheet 20 can be reduced while the unit lenses 21 exhibit the desired optical effect. This allows the dimensions w4 and w1 described above in Modification 1 to be reduced. As a result, the luminance of light that is reflected at the end 2a of the covering portion 2 and reaches the user's eyes can be reduced while the unit lenses 21 exhibit the desired optical effect. Furthermore, the above-described formulas (1) to (3) and formulas (17) to (19) are more likely to be satisfied.

[0119] (Variation 3) In the above-described embodiment, the display device 1 is described as being capable of suppressing the brightness of the double image to less than 50% of the brightness of the direct image when the maximum assumed value of the angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 30°. However, depending on the application of the display device 1, the maximum assumed value of the angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 may be 50°. For example, if the display device 1 is a device whose orientation is difficult for the user to adjust, such as a stationary display, the maximum assumed value of the angle θ2 in normal usage may be 50°. Therefore, the display device 1 may be capable of suppressing the brightness of the double image to less than 50% of the brightness of the direct image when the maximum assumed value of the angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 50°.

[0120] The present inventors have found that if any one of the following is true: the refractive index n of the covering portion 2 is 1.4 or more and less than 1.5 and the following formula (4) is satisfied; the refractive index n of the covering portion 2 is 1.5 or more and less than 1.6 and the following formula (5) is satisfied; or the refractive index n of the covering portion 2 is 1.6 or more and the following formula (6) is satisfied, then when the angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 50° or less, the brightness of the double image can be reduced to less than 50% of the brightness of the direct image.

[0121] The following describes a method for deriving the conditions, including equations (4) to (6), for suppressing the brightness of the double image to less than 50% of the brightness of the direct image when the angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 50° or less. The present inventors conducted a simulation test to determine the above conditions.

[0122] As a simulation test, a simulation test similar to that of the above-described embodiment was conducted, except that the refractive index n, the distance D1, and the distance Y1 were changed, and the ratio of the brightness of the double image to the brightness of the direct image was obtained when the angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 50°.

[0123] 15a to 15c are graphs showing the ratio of the brightness of the double image to the brightness of the direct image when the angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 50°, with the refractive index n fixed and the distance D1 and distance Y1 changed. Fig. 15a is a graph when the refractive index n is fixed at 1.4. Fig. 15b is a graph when the refractive index n is fixed at 1.5. Fig. 15c is a graph when the refractive index n is fixed at 1.6. The results of the simulation test using the graphs shown in Figs. 15a to 15c are presented in the same manner as the results of the simulation test using the graphs shown in Figs. 7a to 7c.

[0124] From the simulation test results shown in Figures 15a to 15c, it can be seen that the smaller the distance D1, the easier it is to reduce the ratio of the brightness of the double image to the brightness of the direct image. From the simulation test results shown in Figures 15a to 15c, it can be seen that the larger the distance Y1, the easier it is to reduce the ratio of the brightness of the double image to the brightness of the direct image. From the simulation test results shown in Figures 15a to 15c, it can be seen that the larger the refractive index n, the easier it is to reduce the ratio of the brightness of the double image to the brightness of the direct image.

[0125] Figure 16a shows the relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% when the refractive index n is 1.4, as obtained from the results of the simulation test shown in Figure 15a. Figure 16b shows the relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% when the refractive index n is 1.5, as obtained from the results of the simulation test shown in Figure 15b. Figure 16c shows the relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% when the refractive index n is 1.6, as obtained from the results of the simulation test shown in Figure 15c. The method of notating the results of the simulation test using graphs shown in Figures 16a to 16c is the same as the method of notating the results of the simulation test using graphs shown in Figures 15a to 15c.

[0126] 16a to 16c, it can be seen that the plots representing the relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% are roughly aligned on a single straight line (dashed line marked with symbol L8). From this, it can be seen that the relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% can be approximated by a linear function. Furthermore, it is clear that the straight line (dashed line marked with symbol L8) representing the relationship between distance D1 and distance Y1 does not pass through the origin of the graph. From this, it can be seen that the relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% can be approximated by a linear function with an intercept that is not zero.

[0127] In Fig. 16a, the plot showing the correspondence relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% was approximated to a linear function by the least squares method, resulting in the following equation (20): In Fig. 16b, the plot showing the correspondence relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% was approximated to a linear function by the least squares method, resulting in the following equation (21): In Fig. 16c, the plot showing the correspondence relationship between distance D1 and distance Y1 when the ratio of the brightness of the double image to the brightness of the direct image is 50% was approximated to a linear function by the least squares method, resulting in the following equation (22):

[0128] As described above, the smaller the distance D1, the smaller the ratio of the brightness of the double image to the brightness of the direct image. Furthermore, the larger the distance Y1, the smaller the ratio of the brightness of the double image to the brightness of the direct image. Therefore, from equation (20), equation (4) is derived as the condition under which the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image when the refractive index n of the covering portion 2 is 1.4. From equation (21), equation (5) is derived as the condition under which the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image when the refractive index n of the covering portion 2 is 1.5. From equation (22), equation (6) is derived as the condition under which the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image when the refractive index n of the covering portion 2 is 1.6. Furthermore, as described above, the larger the refractive index n, the smaller the ratio of the brightness of the double image to the brightness of the direct image. Therefore, if the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image when the refractive index n of the covering portion 2 is 1.4, then the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image even when the refractive index n is 1.4 or more and less than 1.5. If the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image when the refractive index n of the covering portion 2 is 1.5, then the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image even when the refractive index n is 1.5 or more and less than 1.6. If the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image when the refractive index n of the covering portion 2 is 1.6, then the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image even when the refractive index n is 1.6 or more.

[0129] From the above, when the angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 50° or less, the conditions for suppressing the brightness of the double image to less than 50% of the brightness of the direct image are derived as follows: the refractive index n of the covering portion 2 is 1.4 or more and less than 1.5 and the following formula (4) is satisfied; the refractive index n of the covering portion 2 is 1.5 or more and less than 1.6 and the following formula (5) is satisfied; or the refractive index n of the covering portion 2 is 1.6 or more and the following formula (6) is satisfied.

[0130] In Modification 3, when the angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 50° or less, the condition under which the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image is theoretically supported, similar to the condition under which the angle θ2 is 30° or less in the above-described embodiment. Furthermore, the condition under which the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image when the angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 50° or less can also be applied to cases where the light-emitting unit 13 has a rectangular shape other than a square in the first cross section, similar to the condition under which the angle θ2 is 30° or less in the above-described embodiment. Substituting 50° for θ2 and 1.4 for n in "tan(a sin(sin θ2 / n))" in the above-described equation (34) yields a value relatively close to "1.567" shown in the above-described equation (4). Substituting 50° for θ2 and 1.5 for n in "tan(a sin(sin θ2 / n))" in the above-mentioned equation (34) yields a value relatively close to "1.708" shown in the above-mentioned equation (5). Substituting 50° for θ2 and 1.6 for n in "tan(a sin(sin θ2 / n))" in the above-mentioned equation (34) yields a value relatively close to "1.841" shown in the above-mentioned equation (6).

[0131] In the first cross section, the length of the first side 131 is defined as H1, the distance in the second direction d2 between the end 2a of the covering portion 2 and the light-emitting portion 13 is defined as D1, and the distance between the lens surface 21a of the unit lens 21 and the light-emitting portion 13 is defined as Y1. In the display device 1 of the third modification, any one of the following is true: the refractive index n of the covering portion 2 is 1.4 or more but less than 1.5 and the following formula (4) is satisfied; the refractive index n of the covering portion 2 is 1.5 or more but less than 1.6 and the following formula (5) is satisfied; or the refractive index n of the covering portion 2 is 1.6 or more but less than 1.6 and the following formula (6) is satisfied.

[0132] By satisfying the above conditions, it is possible to reduce the brightness of the light that reaches the user's eyes after being reflected at the end 2 a of the covering 2, thereby ensuring that the user can easily view the direct image. In particular, when the angle θ2 that the viewing direction A1 forms with respect to the thickness direction d3 is 50° or less, the ratio of the brightness of the double image to the brightness of the direct image can be made less than 50%.

[0133] Furthermore, in the display device 1 of Modification 3, the following condition may be satisfied between the distance Y3 and the length H1 and distance D1 in an arbitrary first cross section: the refractive index n of the covering portion 2 is 1.4 or greater but less than 1.5 and the following formula (23) is satisfied; the refractive index n of the covering portion 2 is 1.5 or greater but less than 1.6 and the following formula (24) is satisfied; or the refractive index n of the covering portion 2 is 1.6 or greater but the following formula (25) is satisfied. By satisfying the above condition, when the assumed angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 50° or less, the luminance of light that is reflected at the end 2 a of the covering portion 2 and reaches the user's eyes can be reduced, thereby ensuring a more stable and easy view of the direct image by the user.

[0134] (Variation 4) In the above-described embodiment and each variation, an example has been described in which the optical sheet 20 has a plurality of unit lenses 21 aligned in the first direction d1 and extending in the second direction d2. In particular, in the above-described embodiment and each variation, a display device 1 has been described in which one unit lens 21 corresponds to one of the second-direction unit area rows 10c. However, the configuration of the optical sheet 20 is not limited thereto. FIG. 17 is a plan view showing the optical sheet 20 included in the display device 1 of Variation 4, as observed from the side opposite to the side facing the light-emitting substrate 10. FIG. 18 is a cross-sectional view of the display device 1 of Variation 4, in which the optical sheet 20 is cut along line XVIII-XVIII in FIG. 17. FIG. 18 is an enlarged view of the periphery of the end 2a of the covering portion 2 of the display device 1. FIG. 18 corresponds to a cross-section of the display device 1 cut along a plane parallel to the thickness direction d3 of the optical sheet 20 and passing through the light-emitting portion 13. Such a cross section passing through the light-emitting section 13 and parallel to the thickness direction d3 of the optical sheet 20 is referred to as a second cross section. In Fig. 18, the second cross section is a cross section parallel to the second direction d2. Although not shown, the second cross section may be a cross section parallel to the first direction d1, or may be a cross section non-parallel to both the first direction d1 and the second direction d2.

[0135] The optical sheet 20 of Modification 4 has a sheet-like main body 23, similar to the optical sheet 20 of the above-described embodiment. As shown in FIGS. 17 and 18 , the optical sheet 20 of Modification 4 has a sheet-like main body 23 and a plurality of isolated lenses 24 arranged on the surface of the main body 23. The dashed line indicated by the symbol L9 in FIG. 18 is a virtual line indicating the boundary between the plurality of isolated lenses 24 and the main body 23. In the example shown in FIG. 17 , adjacent isolated lenses 24 in the first direction d1 and the second direction d2 are in contact with each other. In this case, a plane passing through the position where the lens surfaces 24a of adjacent isolated lenses 24 are connected and perpendicular to the front direction (thickness direction d3) of the display device 1 can be considered as the boundary L9 between the isolated lenses 24 and the main body 23. Although not shown, as described below, a gap may be provided between adjacent isolated lenses 24. In this case, the plane that passes through the position where the surface of the optical sheet 20 formed between adjacent isolated lenses 24 and the lens surface 24a of the isolated lens 24 are connected and is perpendicular to the front direction (thickness direction d3) of the display device 1 can be considered to be the boundary L9 between the isolated lens 24 and the main body portion 23.

[0136] Like the optical sheet 20 of the above-described embodiment, the optical sheet 20 of the fourth modification also changes the light distribution characteristics of light emitted from the light-emitting substrate 10 to desired light distribution characteristics. In particular, the optical sheet 20 changes the light distribution characteristics so as to provide the user with desired visual information when the user observes the display device 1 from the intended use direction. The isolated lens 24 is an element that refracts incident light at its surface, i.e., the lens surface 24a, to change the direction of travel of the light. As an example, the isolated lens 24 focuses light that is emitted from the light-emitting substrate 10 and diffused in the first direction d1 and the second direction d2 toward the front of the display device 1.

[0137] Unlike the unit lenses 21 described in the above embodiment, the isolated lenses 24 do not extend in the second direction d2. When the optical sheet 20 of the fourth modification is cut along a cross section parallel to the thickness direction d3 and perpendicular to the second direction d2, the cross-sectional shape of the isolated lenses 24 can change depending on the position of the cross section in the second direction d2.

[0138] Each of the multiple isolated lenses 24 is arranged corresponding to each of the multiple unit regions 10a. Corresponding to the unit region 10a means that the isolated lens 24 overlaps the center of the light-emitting section 13 of the unit region 10a in the first direction d1 and the second direction d2 in the thickness direction d3. In the example shown in FIG. 18 , each of the multiple isolated lenses 24 overlaps the center C3 of the light-emitting section 13 of each of the multiple unit regions 10a in the first direction d1 and the second direction d2 in the thickness direction d3. In the example shown in FIG. 18 , the center C4 of each of the multiple isolated lenses 24 in the first direction d1 and the second direction d2 overlaps the center C3 of the light-emitting section 13 of each of the multiple unit regions 10a in the first direction d1 and the second direction d2.

[0139] In the display device 1 of Variation 4, the multiple isolated lenses 24 are arranged two-dimensionally. As an example, the multiple unit regions 10a are aligned in the first direction d1 and the second direction d2. Furthermore, as shown in FIG. 17 , the multiple isolated lenses 24 are aligned in two different directions on a plane, the first direction d1 and the second direction d2. In the example shown in FIG. 17 , the multiple isolated lenses 24 are in contact with each other in the first direction d1 and the second direction d2. Although not shown, gaps may be provided between the multiple isolated lenses 24 in the first direction d1 and the second direction d2. In the example shown in FIG. 17 , the multiple isolated lenses 24 are aligned in the first direction d1 and the second direction d2 at a common and constant arrangement pitch p3. In the example shown in FIG. 17 , the optical sheet 20 is a so-called fly's eye lens.

[0140] As an example, when the optical sheet 20 is observed from the thickness direction d3 (see FIG. 17), the outline of each of the isolated lenses 24 has a circular shape.

[0141] The arrangement and contour shape of the isolated lenses 24 are not limited to the example shown in FIG. 17 . Although not shown, the contour shape of the isolated lenses 24 when observed from the thickness direction d3 may be a four-fold symmetric shape other than a circle. The contour shape of the isolated lenses 24 may be a quadrilateral or an approximately quadrilateral. The contour shape of the isolated lenses 24 may be a square or an approximately square. The isolated lenses 24 having a quadrilateral or approximately quadrilateral contour shape may be arranged in a lattice pattern. Although not shown, the isolated lenses 24 may be arranged in a first arrangement direction and a second arrangement direction inclined by 60° with respect to the first arrangement direction. In this case, although not shown, the contour shape of the isolated lenses 24 when observed from the thickness direction d3 may be a six-fold symmetric shape other than a circle. The contour shape of the isolated lenses 24 may be a regular hexagon or an approximately regular hexagon. The isolated lenses 24 having a regular hexagon or an approximately regular hexagon contour shape may be arranged in a honeycomb pattern.

[0142] In the illustrated example, the isolated lens 24 changes the traveling direction of light by refraction at the lens surface 24a. In the examples shown in Figures 17 and 18, the isolated lens 24 has a shape corresponding to a portion of a sphere.

[0143] As described above, since the isolated lens 24 has a shape equivalent to a portion of a sphere and its center C4 overlaps with the center C3, the isolated lens 24 focuses the light that is diffused in the first direction and the second direction d2 emitted from the light-emitting substrate 10 toward the front of the display device 1.

[0144] The method for manufacturing the display device 1 including the optical sheet 20 of Modification 4 is similar to the method for manufacturing the display device 1 including the optical sheet 20 of the above-described embodiment. For example, the optical sheet 20 of Modification 4 in which the main body 23 and the isolated lenses 24 are integrally formed can be manufactured by the same method as the method for manufacturing the optical sheet 20 in which the main body 23 and the unit lenses 21 are integrally formed of the above-described embodiment.

[0145] As shown in FIG. 18 , in the second cross section, the light-emitting unit 13 has a rectangular shape including a third side 133 extending in the thickness direction d3 of the optical sheet 20 and a fourth side 134 perpendicular to the third side 133 and having a length equal to or greater than the length of the third side 133. The rectangle includes a square. That is, the length of the third side 133 may be equal to the length of the fourth side 134. In any second cross section, the light-emitting unit 13 has a rectangular shape including the third side 133 and the fourth side 134. As an example, the light-emitting unit 13 has the shape of the rectangular parallelepiped described above. As a result, in any second cross section, the light-emitting unit 13 has a rectangular shape including the third side 133 and the fourth side 134.

[0146] 18 , the second cross section shows the end 2 a of the covering portion 2. In the example shown in Fig. 18 , the end 2 a of the covering portion 2 includes the end of the main body portion 23 of the optical sheet 20, the end of the sealing layer 40, and the end of the adhesive layer 50. The end 2 a of the covering portion 2 is formed by a surface parallel to the thickness direction d3 of the optical sheet 20.

[0147] For the same reason as in the above-described embodiment, it is required to reduce the luminance of light that is emitted from the light-emitting unit 13, reflected at the end 2 a of the covering unit 2 that appears in the first cross section, and reaches the user's eyes, it is also required in Modification 4 to reduce the luminance of light that is emitted from the light-emitting unit 13, reflected at the end 2 a of the covering unit 2 that appears in the second cross section, and reaches the user's eyes. That is, in Modification 4, from the perspective of ensuring that the direct image is easily visible to the user, it is required to reduce the luminance of light that is emitted from the light-emitting unit 13, reflected at the end 2 a of the covering unit 2 that appears in the second cross section, and reaches the user's eyes. In particular, it is required to keep the luminance of the double image to less than 50% of the luminance of the direct image.

[0148] The conditions under which the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image in the display device 1 of Modification 4 will be described. In the second cross section, the length of the third side 133 is defined as H2. In the second cross section, the distance between the end 2a of the covering portion 2 and the light-emitting portion 13 in a direction perpendicular to the thickness direction d3 of the optical sheet 20 is defined as D2. In the second cross section, the distance between the boundary L9 between the main body portion 23 and the isolated lens 24 and the light-emitting portion 13 in the thickness direction d3 of the optical sheet 20 is defined as Y2. In this case, if the relationship between the length H2, the distance D2, the distance Y2, and the refractive index n satisfies the relationship between the length H1, the distance D1, the distance Y1, and the refractive index n described in the above embodiment when the brightness of the double image is less than 50% of the brightness of the direct image, it is considered that the brightness of the double image can be suppressed to less than 50% of the brightness of the direct image in the display device 1 of Modification 4.

[0149] By replacing the length H1, distance D1, and distance Y1 in equation (1) in the above embodiment with the length H2, distance D2, and distance Y2, respectively, the following equation (7) is obtained. By replacing the length H1, distance D1, and distance Y1 in equation (2) in the above embodiment with the length H2, distance D2, and distance Y2, respectively, the following equation (8) is obtained. By replacing the length H1, distance D1, and distance Y1 in equation (3) in the above embodiment with the length H2, distance D2, and distance Y2, respectively, the following equation (9) is obtained. Therefore, when any one of the following conditions is met: the refractive index n of the covering portion 2 is 1.4 or more and less than 1.5 and the following formula (7) is satisfied; the refractive index n of the covering portion 2 is 1.5 or more and less than 1.6 and the following formula (8) is satisfied; or the refractive index n of the covering portion 2 is 1.6 or more and the following formula (9) is satisfied, the luminance of light that is reflected at the end 2 a of the covering portion 2 and reaches the user's eyes can be reduced, thereby ensuring ease of viewing of the direct image by the user. In particular, when the assumed angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 30° or less, the ratio of the luminance of the double image to the luminance of the direct image can be made less than 50%.

[0150] By replacing the length H1, distance D1, and distance Y1 in equation (4) in the above embodiment with the length H2, distance D2, and distance Y2, respectively, the following equation (10) is obtained. By replacing the length H1, distance D1, and distance Y1 in equation (5) in the above embodiment with the length H2, distance D2, and distance Y2, respectively, the following equation (11) is obtained. By replacing the length H1, distance D1, and distance Y1 in equation (6) in the above embodiment with the length H2, distance D2, and distance Y2, respectively, the following equation (12) is obtained. Therefore, when any one of the following conditions is met: the refractive index n of the covering portion 2 is 1.4 or more and less than 1.5 and the following formula (10) is satisfied; the refractive index n of the covering portion 2 is 1.5 or more and less than 1.6 and the following formula (11) is satisfied; or the refractive index n of the covering portion 2 is 1.6 or more and the following formula (12) is satisfied, the luminance of light that is reflected at the end 2 a of the covering portion 2 and reaches the user's eyes can be reduced, thereby ensuring ease of viewing of the direct image by the user. In particular, when the assumed angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 50° or less, the ratio of the luminance of the double image to the luminance of the direct image can be made less than 50%.

[0151] In the second cross section of the display device 1 in the above-described embodiment, the optical sheet 20 has a plurality of unit lenses 21 aligned in the first direction d1 and extending in the second direction d2. The light-emitting section 13 may have a rectangular shape including a third side 133 and a fourth side 134. In this case, in the second cross section of the display device 1, the distance between the boundary L1 between the main body 23 and the unit lenses 21 and the light-emitting section 13 in the thickness direction d3 of the optical sheet 20 is defined as Y5 (see FIG. 4 ). Replacing the distance Y2 in the above-described equation (7) with the distance Y5 yields the following equation (26). Replacing the distance Y2 in the above-described equation (8) with the distance Y5 yields the following equation (27). Replacing the distance Y2 in the above-described equation (9) with the distance Y5 yields the following equation (28). When any one of the following conditions is satisfied: the refractive index n of the covering portion 2 is 1.4 or more but less than 1.5 and the following formula (26) is satisfied; the refractive index n of the covering portion 2 is 1.5 or more but less than 1.6 and the following formula (27) is satisfied; or the refractive index n of the covering portion 2 is 1.6 or more but the following formula (28) is satisfied, in a display device 1 in which the optical sheet 20 has a plurality of unit lenses 21 arranged in the first direction d1 and extending in the second direction d2, the luminance of light that is reflected at the end 2 a of the covering portion 2 and reaches the user's eyes can be reduced, thereby ensuring more stable ease of viewing of the direct image by the user. In particular, the luminance of light that is reflected at the end 2 a other than the first end 2 b of the covering portion 2 (for example, the end 2 a designated by the symbol 2 e in FIG. 4 ) and reaches the user's eyes can be sufficiently reduced. In particular, when the assumed angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 30° or less, the brightness of the light that is reflected at the end 2a other than the first end 2b of the covering portion 2 and reaches the user's eyes can be sufficiently reduced.

[0152] By replacing the distance Y2 in the above-described formula (10) with the distance Y5, the following formula (29) is obtained. By replacing the distance Y2 in the above-described formula (11) with the distance Y5, the following formula (30) is obtained. By replacing the distance Y2 in the above-described formula (12) with the distance Y5, the following formula (31) is obtained. When any one of the following is true: the refractive index n of the covering portion 2 is 1.4 or more and less than 1.5 and the following formula (29) is satisfied; the refractive index n of the covering portion 2 is 1.5 or more and less than 1.6 and the following formula (30) is satisfied; or the refractive index n of the covering portion 2 is 1.6 or more and the following formula (31) is satisfied, in the display device 1 in which the optical sheet 20 has a plurality of unit lenses 21 arranged in the first direction d1 and extending in the second direction d2, the luminance of light that is reflected at the end 2 a of the covering portion 2 and reaches the user's eyes can be reduced, thereby ensuring more stable ease of viewing of the direct image by the user. In particular, it is possible to sufficiently reduce the luminance of light that reaches the user's eyes after being reflected at the end 2 a other than the first end 2 b of the covering 2 (for example, the end 2 a designated by the reference symbol 2 e in FIG. 4 ). In particular, when the assumed angle θ2 that the viewing direction A1 makes with respect to the thickness direction d3 is 50° or less, it is possible to sufficiently reduce the luminance of light that reaches the user's eyes after being reflected at the end 2 a other than the first end 2 b of the covering 2.

[0153] A display 100 including a plurality of display devices 1 may be manufactured using the display device 1 of Modification 4. FIG. 19 is a diagram showing a display 100 including a plurality of display devices 1 of Modification 4. As shown in FIG. 19 , in a display 100 including a plurality of display devices 1, the plurality of display devices 1 may be arranged so as to be in contact with each other. In this case, the ends 2 a of the plurality of display devices 1 are in contact with each other in the display 100. In this case, the ends 2 a of the display devices 1 may be disposed at positions away from the ends of the display 100. In particular, the ends 2 a of the display devices 1 may be disposed near the center of the display 100 in the second direction d2. According to the display device 1 of this embodiment, even when the display device 1 is incorporated into the display 100 in this manner, the brightness of light reflected at the ends 2 a and reaching the user's eyes can be reduced. This ensures easy visibility of direct images throughout the entire display 100. In particular, it is easy to prevent the seams of the display 100 where the ends 2 a of the plurality of display devices 1 are in contact with each other from being visible due to light reflection at the ends 2 a.

[0154] The components disclosed in the above-described embodiment and each modification may be combined as needed, or some components may be omitted from all the components shown in the above-described embodiment and each modification.

[0155] REFERENCE SIGNS LIST 1 display device 2 covering portion 2a end portion 2b first end portion 10 light-emitting substrate 10a unit region 10c unit region second direction row 11 semiconductor layer 13 light-emitting portion 131 first side 132 second side 133 third side 134 fourth side 13R first light-emitting portion 13G second light-emitting portion 13B third light-emitting portion 20 optical sheet 21 unit lens 21a lens surface 23 main body portion 24 isolated lens 24a lens surface 100 display

Claims

1. A light emitting substrate having a semiconductor layer divided into a plurality of unit areas and light emitting sections arranged in the plurality of unit areas; and a covering section including an optical sheet arranged opposite the light emitting substrate and covering the light emitting sections, wherein the optical sheet has a plurality of unit lenses arranged in a first direction and extending in a second direction non-parallel to the first direction, the plurality of unit areas are aligned in the first direction and the second direction, and in a first cross section passing through the light emitting sections and parallel to the second direction and the thickness direction of the optical sheet, the light emitting sections have a rectangular shape including a first side extending in the thickness direction of the optical sheet and a second side extending in the second direction and having a length equal to or greater than the length of the first side, a display device in which, in the first cross section, the length of the first side is H1, the distance between the end of the covering portion and the light-emitting portion in the second direction is D1, and the distance between the lens surface of the unit lens and the light-emitting portion is Y1, and any one of the following is true: a refractive index n of the covering portion is 1.4 or more and less than 1.5 and the following formula (1) is satisfied; a refractive index n of the covering portion is 1.5 or more and less than 1.6 and the following formula (2) is satisfied; or a refractive index n of the covering portion is 1.6 or more and the following formula (3) is satisfied.

2. A light emitting substrate having a semiconductor layer divided into a plurality of unit areas and light emitting sections arranged in the plurality of unit areas; and a covering section including an optical sheet arranged opposite the light emitting substrate and covering the light emitting sections, wherein the optical sheet has a plurality of unit lenses arranged in a first direction and extending in a second direction non-parallel to the first direction, the plurality of unit areas are aligned in the first direction and the second direction, and in a first cross section passing through the light emitting sections and parallel to the second direction and the thickness direction of the optical sheet, the light emitting sections have a rectangular shape including a first side extending in the thickness direction of the optical sheet and a second side extending in the second direction and having a length equal to or greater than the length of the first side, In the first cross section, when the length of the first side is H1, the distance between the end of the covering portion and the light-emitting portion in the second direction is D1, and the distance between the lens surface of the unit lens and the light-emitting portion is Y1, any one of the following is true: the refractive index n of the covering portion is 1.4 or more and less than 1.5 and the following formula (4) is satisfied; the refractive index n of the covering portion is 1.5 or more and less than 1.6 and the following formula (5) is satisfied; or the refractive index n of the covering portion is 1.6 or more and the following formula (6) is satisfied.

3. The display device according to claim 1 or 2, wherein, in a cross section perpendicular to the second direction, the unit lenses have a shape corresponding to a part of a circle or a part of an ellipse.

4. A display device as described in claim 1 or 2, wherein in the first cross section, the dimension of the end of the covering portion in the thickness direction of the optical sheet is smaller than the maximum dimension of the covering portion in the thickness direction of the optical sheet.

5. A display device as described in claim 4, wherein the covering portion has an end region that extends in the second direction and includes the end of the covering portion, and in the first cross section, the dimension of the covering portion in the thickness direction of the optical sheet gradually decreases within the end region along the second direction toward the end of the covering portion.

6. The display device according to claim 1, wherein the unit lenses are linear Fresnel lenses.

7. A display comprising a plurality of display devices according to claim 1 or 2, wherein the plurality of display devices are arranged so as to be in contact with each other at least in the second direction.

8. A light emitting substrate having a semiconductor layer divided into a plurality of unit areas and light emitting portions arranged in the plurality of unit areas; and a covering portion including an optical sheet arranged opposite to the light emitting substrate and covering the light emitting portions, wherein the optical sheet has a sheet-like main body and a plurality of isolated lenses arranged on a surface of the main body, and in a second cross section passing through the light emitting portions and parallel to the thickness direction of the optical sheet, the light emitting portions have a rectangular shape including a third side extending in the thickness direction of the optical sheet and a fourth side perpendicular to the third side and having a length equal to or greater than the length of the third side, a display device in which, in the second cross section, a length of the third side is H2, a distance between the end of the covering portion and the light-emitting portion in a direction perpendicular to the thickness direction of the optical sheet is D2, and a distance between the boundary between the main body portion and the isolated lens and the light-emitting portion in the thickness direction of the optical sheet is Y2, and any one of the following is true: a refractive index n of the covering portion is 1.4 or more and less than 1.5 and the following formula (7) is satisfied; a refractive index n of the covering portion is 1.5 or more and less than 1.6 and the following formula (8) is satisfied; or a refractive index n of the covering portion is 1.6 or more and the following formula (9) is satisfied.

9. A light emitting substrate having a semiconductor layer divided into a plurality of unit areas and light emitting portions arranged in the plurality of unit areas; and a covering portion including an optical sheet arranged opposite to the light emitting substrate and covering the light emitting portions, wherein the optical sheet has a sheet-like main body and a plurality of isolated lenses arranged on a surface of the main body, and in a second cross section passing through the light emitting portions and parallel to the thickness direction of the optical sheet, the light emitting portions have a rectangular shape including a third side extending in the thickness direction of the optical sheet and a fourth side perpendicular to the third side and having a length equal to or greater than the length of the third side, a display device in which, in the second cross section, a length of the third side is H2, a distance between the end of the covering portion and the light-emitting portion in a direction perpendicular to the thickness direction of the optical sheet is D2, and a distance between the boundary between the main body portion and the isolated lens and the light-emitting portion in the thickness direction of the optical sheet is Y2, and any one of the following is true: a refractive index n of the covering portion is 1.4 or more and less than 1.5 and the following formula (10) is satisfied; a refractive index n of the covering portion is 1.5 or more and less than 1.6 and the following formula (11) is satisfied; or a refractive index n of the covering portion is 1.6 or more and the following formula (12) is satisfied.

10. A display comprising a plurality of display devices according to claim 8 or 9, wherein the plurality of display devices are arranged so as to be in contact with each other.

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