Optical member, surface light source device, and display device

Abstract

This invention provides an optical component, a surface light source device, and a display device. The optical component includes: a light guide plate having a light-emitting surface and a back surface facing the light-emitting surface; and an optical sheet having a prism surface facing the light-emitting surface. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction (D1) and a plurality of connecting surfaces not parallel to the inclined surfaces. The inclined surfaces are inclined relative to the first direction such that a first side of the inclined surfaces approaches the light-emitting surface in the first direction. The optical sheet includes a plurality of unit prisms arranged along the first direction. Each unit prism includes a first prism surface located on a first side in the first direction and a second prism surface facing the first prism surface from the first direction. The prism surface includes a first prism surface and a second prism surface. The first prism surface includes a first element surface, a second element surface, and a third element surface. The second element surface is located between the first element surface and the third element surface. The difference in inclination angle between the first element surface and the third element surface is 5° or more.

Description

[0001] This application is a divisional application of Chinese Patent Application No. 202480032392.1 (PCT / JP2024 / 017364), filed on May 10, 2024, entitled "Optical Components, Surface Light Source Device and Display Device". Technical Field

[0002] This disclosure relates to optical components, surface light source devices, and display devices. Background Technology

[0003] As disclosed in Patent Document 1 (JP 2016-95347A), surface light source devices including a light-emitting surface are known. The conventional surface light source device disclosed in Patent Document 1, being an edge-light type, includes a reflector, a light guide plate, and an optical sheet. In the surface light source device of Patent Document 1, the light guide plate includes a light-emitting surface and a back surface facing the light-emitting surface. The conventional back surface includes an inclined surface that is tilted relative to the light-emitting surface. Regarding the angle of incidence of light traveling within the light guide plate towards the light-emitting surface, this angle decreases by twice the angle of the inclined surface each time it is reflected. By repeatedly reflecting at the inclined surface, the angle of incidence of light towards the light-emitting surface is less than the critical angle of total internal reflection, allowing light to exit from the light guide plate. In this surface light source device, the light emission direction of the light emitted from the light-emitting surface of the light guide plate is biased within a very narrow angular range that is significantly tilted relative to the stacking direction of the light guide plate and the optical sheet.

[0004] In the surface light source device of Patent Document 1, the optical sheet includes a prism surface facing the light-emitting surface of the light guide plate. The prism surface repeatedly includes a first prism surface and a second prism surface. The second prism surface becomes the incident surface of light from the light guide plate. The first prism surface reflects the light that has passed through the second prism surface. Due to the reflection from the first prism surface, the angle between the stacking direction of the light guide plate and the optical sheet and the direction of light travel becomes smaller. In a surface light source device using such a light guide plate and optical sheet, the brightness in specific directions, such as the frontal direction, can be improved.

[0005] Light traveling at a significant angle relative to the stacking direction can enter the portion of the first prism surface that is near the end of the light guide plate. Light traveling at a smaller angle relative to the stacking direction enters the portion of the first prism surface that is away from the base of the light guide plate. In the surface light source device disclosed in Patent Document 1, the first prism surface is a folded surface. Near the end of the light guide plate, the angle of the first prism surface relative to the stacking direction is relatively large. On the base of the light guide plate, the angle of the first prism surface relative to the stacking direction is relatively small. By making the first prism surface a folded surface, the brightness in specific directions such as the frontal direction can be further improved.

[0006] As described above, in conventional surface light source devices, optical components including light guide plates and optical sheets exhibit excellent light-focusing capabilities. This allows for increased brightness in specific directions, such as the frontal direction. On the other hand, since less light is emitted in directions other than these specific directions, the viewing angle becomes narrower. Summary of the Invention

[0007] The purpose of this disclosure is to effectively expand the viewing angle in a display device that uses a surface light source.

[0008] The optical components of a first surface light source device according to one embodiment of this disclosure include: A light guide plate comprising a light-emitting surface and a back surface facing the light-emitting surface; and An optical element comprising a prism surface facing the light-emitting surface. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The optical sheet comprises a plurality of unit prisms arranged in the first direction. Each unit prism includes: a first prism surface located on a first side in the first direction; and a second prism surface facing the first prism surface from the first direction. The prism surface includes a first prism surface and a second prism surface. The first prism surface includes a first feature surface, a second feature surface, and a third feature surface. The second feature surface is located between the first feature surface and the third feature surface. The difference in tilt angle between the first feature surface and the third feature surface is greater than 5°.

[0009] The optical components of a second surface light source device according to one embodiment of the present disclosure include: A light guide plate comprising a light-emitting surface and a back surface facing the light-emitting surface; and An optical element comprising a prism surface facing the light-emitting surface. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The optical sheet comprises a plurality of unit prisms arranged in the first direction. Each unit prism includes: a first prism surface located on a first side in the first direction; and a second prism surface facing the first prism surface from the first direction. The prism surface includes a first prism surface and a second prism surface. The first prism surface includes a first feature surface, a second feature surface, and a third feature surface. The second feature surface is located between the first feature surface and the third feature surface. The difference in tilt angle between the first feature surface and the third feature surface is greater than twice the angle of the tilt surface relative to the first direction.

[0010] The optical component of the third surface light source device in one embodiment of this disclosure is an optical component for a surface light source device disposed facing the display panel, wherein... The optical component includes: A light guide plate comprising a light-emitting surface and a back surface facing the light-emitting surface; and An optical element comprising a prism surface facing the light-emitting surface. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The spacing between the connecting surfaces in the first direction is larger than the spacing between the pixels of the display panel in the first direction.

[0011] The optical components of a fourth surface light source device according to one embodiment of this disclosure include: A light guide plate comprising a light-emitting surface and a back surface facing the light-emitting surface; and An optical element comprising a prism surface facing the light-emitting surface. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The spacing between the connecting surfaces in the first direction is 0.060 mm or more.

[0012] One embodiment of the present disclosure includes a first surface light source device comprising: A light guide plate includes a light-emitting surface, a back surface facing the light-emitting surface, and a light-incident surface located between the light-emitting surface and the back surface; An optical sheet comprising a prism surface facing the light-emitting surface; The reflective sheet faces the back side; and The light source emits light that is incident on the light guide plate. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The optical sheet comprises a plurality of unit prisms arranged in the first direction. Each unit prism includes: a first prism surface located on a first side in the first direction; and a second prism surface facing the first prism surface from the first direction. The prism surface includes a first prism surface and a second prism surface. The first prism surface includes a first feature surface, a second feature surface, and a third feature surface. The second feature surface is located between the first feature surface and the third feature surface. The difference in tilt angle (°) between the first element surface and the third element surface is greater than or equal to half the peak and half the width (°) of the angular distribution of brightness at the light-emitting surface.

[0013] The optical components of a fifth surface light source device according to one embodiment of this disclosure include: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The reflective sheet, starting from the light guide plate, sequentially comprises a surface layer, an internal diffusion layer, and a metal layer. The internal diffusion layer comprises a base layer and a light-diffusing component retained in the base layer.

[0014] The optical components of a sixth surface light source device according to one embodiment of this disclosure include: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The reflective sheet has a specular gloss level of less than 200 at an incident angle of 20°. The reflective sheet has a specular gloss of 75 or higher at an incident angle of 85°.

[0015] The optical components of a seventh surface light source device according to one embodiment of this disclosure include: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The specular gloss G(20) of the reflective sheet at an incident angle of 20°, the specular gloss G(60) of the reflective sheet at an incident angle of 60°, and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: |G(60)-G(85)|<|G(20)-G(60)|.

[0016] The optical components of the eighth surface light source device according to one embodiment of this disclosure include: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The specular gloss G(20) of the reflective sheet at an incident angle of 20°, the specular gloss G(60) of the reflective sheet at an incident angle of 60°, and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: |G(60)-G(85)| / ((G(60)+G(85)) / 2)<|G(20)-G(60)| / ((G(20)+G(60)) / 2).

[0017] The optical components of the ninth surface light source device according to one embodiment of this disclosure include: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The diffuse reflectivity of the reflective sheet is above 65% and below 90%.

[0018] The optical components of the tenth surface light source device according to one embodiment of this disclosure include: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The reflective sheet has a specular gloss level of 75 or higher and 110 or lower at an incident angle of 85°.

[0019] The optical components of the eleventh surface light source device according to one embodiment of this disclosure include: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The ratio of the specular gloss of the reflective sheet at an incident angle of 85° to the specular gloss of the reflective sheet at an incident angle of 20° is 0.85 or higher.

[0020] The optical components of the twelfth surface light source device according to one embodiment of this disclosure include: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The specular gloss G(20) of the reflective sheet at an incident angle of 20° and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: G(20)-G(85)≤0.

[0021] One embodiment of the second surface light source device disclosed herein includes: Any optical component of one embodiment of this disclosure; and A light source that emits light incident on the light guide plate.

[0022] One embodiment of the display device disclosed herein includes: An arbitrary surface light source device according to one embodiment of this disclosure; and The display panel faces the surface light source device.

[0023] According to this disclosure, the viewing angle in a display device that uses a surface light source can be effectively expanded. Attached Figure Description

[0024] Figure 1 This is a diagram used to illustrate one embodiment of the present disclosure. Figure 1 This is a longitudinal sectional view showing a schematic structure of a display device, a surface light source device, and optical components.

[0025] Figure 2 It is shown Figure 1 A top view of an example of pixel arrangement in the display device shown.

[0026] Figure 3 yes Figure 1 The longitudinal sectional view of the surface light source device and optical components shown. Figure 3 It is a diagram used to illustrate the function.

[0027] Figure 4 yes Figure 3 A top view of the surface light source device and optical components shown.

[0028] Figure 5 It shows that it can be included Figure 3 A perspective view of an example of a light guide plate in a surface light source device and optical components.

[0029] Figure 6 It is shown Figure 5 A partially enlarged cross-sectional view of the light guide plate shown.

[0030] Figure 7 It shows that it can be included Figure 3 A perspective view of an example of an optical element in a surface light source device and optical components.

[0031] Figure 8 It is shown Figure 7 A partially enlarged cross-sectional view of the optical plate shown.

[0032] Figure 9 It shows that it can be included Figure 3 A longitudinal sectional view of an example of a reflector in a surface light source device and optical components.

[0033] Figure 10 It is a graph showing the angular distribution of brightness on the light-emitting surface of the light guide plate.

[0034] Figure 11It is a graph showing the angular distribution of brightness on the first surface of the optical plate.

[0035] Figure 12 Is with Figure 3 The corresponding sectional view is a diagram showing a modified example of the light guide plate.

[0036] Figure 13 It is shown Figure 12 A graph showing the luminance angle distribution on the first surface of the optical plate in the surface light source device. Detailed Implementation

[0037] This implementation involves the following <1> to <54>.

[0038] <1>

[0039] An optical component of a surface light source device, comprising: A light guide plate comprising a light-emitting surface and a back surface facing the light-emitting surface; and An optical element comprising a prism surface facing the light-emitting surface. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The optical sheet comprises a plurality of unit prisms arranged in the first direction. Each unit prism includes: a first prism surface located on a first side in the first direction; and a second prism surface facing the first prism surface from the first direction. The prism surface includes a first prism surface and a second prism surface. The first prism surface includes a first feature surface, a second feature surface, and a third feature surface. The second feature surface is located between the first feature surface and the third feature surface. The difference in tilt angle between the first feature surface and the third feature surface is greater than 5°.

[0040] <2>

[0041] The optical components of the surface light source device according to <1>, wherein, The difference in tilt angle between the first feature surface and the third feature surface is greater than twice the angle of the tilt surface relative to the first direction.

[0042] <3>

[0043] An optical component of a surface light source device, comprising: A light guide plate comprising a light-emitting surface and a back surface facing the light-emitting surface; and An optical element comprising a prism surface facing the light-emitting surface. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The optical sheet comprises a plurality of unit prisms arranged in the first direction. Each unit prism includes: a first prism surface located on a first side in the first direction; and a second prism surface facing the first prism surface from the first direction. The prism surface includes a first prism surface and a second prism surface. The first prism surface includes a first feature surface, a second feature surface, and a third feature surface. The second feature surface is located between the first feature surface and the third feature surface. The difference in tilt angle between the first feature surface and the third feature surface is greater than twice the angle of the tilt surface relative to the first direction.

[0044] <4>

[0045] The optical component of the surface light source device according to any one of <1> to <3>, wherein... The spacing between the connecting surfaces in the first direction is 0.060 mm or more.

[0046] <5>

[0047] The optical component according to any one of <1> to <4>, wherein... The spacing between the connecting surfaces in the first direction is larger than the spacing between the pixels of the display panel disposed facing the ground with the surface light source device along the first direction.

[0048] <6>

[0049] The optical component according to any one of <1> to <5>, wherein... The ratio of the spacing of the connecting surface in the first direction to the spacing of the pixels of the display panel disposed facing the ground with the surface light source device in the first direction is 1.0 or more and 2.2 or less.

[0050] <7>

[0051] The optical component according to any one of <1> to <6>, wherein, The optical component has a reflective sheet facing the back side.

[0052] <8>

[0053] According to the optical component described in <7>, wherein... The reflective sheet, starting from the light guide plate, sequentially comprises a surface layer, an internal diffusion layer, and a metal layer. The internal diffusion layer comprises a base layer and a light-diffusing component retained in the base layer.

[0054] <9>

[0055] According to the optical component described in <7> or <8>, wherein, The reflective sheet has a specular gloss level of less than 200 at an incident angle of 20°. The reflective sheet has a specular gloss of 75 or higher at an incident angle of 85°.

[0056] <10>

[0057] The optical component according to any one of <7> to <9>, wherein... The specular gloss G(20) of the reflective sheet at an incident angle of 20°, the specular gloss G(60) of the reflective sheet at an incident angle of 60°, and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: |G(60)-G(85)|<|G(20)-G(60)|.

[0058] <11>

[0059] The optical component according to any one of <7> to <10>, wherein... The specular gloss G(20) of the reflective sheet at an incident angle of 20°, the specular gloss G(60) of the reflective sheet at an incident angle of 60°, and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: |G(60)-G(85)| / ((G(60)+G(85)) / 2)<|G(20)-G(60)| / ((G(20)+G(60)) / 2).

[0060] <12>

[0061] The optical component according to any one of <7> to <11>, wherein, The diffuse reflectivity of the reflective sheet is above 65% and below 90%.

[0062] <13>

[0063] The optical component according to any one of <7> to <12>, wherein, The reflective sheet has a specular gloss of 75 or higher at an incident angle of 85°.

[0064] <14>

[0065] The optical component according to any one of <7> to <13>, wherein... The ratio of the specular gloss of the reflective sheet at an incident angle of 85° to the specular gloss of the reflective sheet at an incident angle of 20° is 0.85 or higher.

[0066] <15>

[0067] The optical component according to any one of <7> to <14>, wherein... The specular gloss G(20) of the reflective sheet at an incident angle of 20° and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: G(20)-G(85)≤0.

[0068] <16>

[0069] The optical component according to any one of <7> to <15>, wherein... The ratio of the specular gloss of the reflective sheet at an incident angle of 85° to the specular gloss of the reflective sheet at an incident angle of 60° is greater than 0.55 and less than 2.0.

[0070] <17>

[0071] The optical component according to any one of <7> to <16>, wherein, The specular gloss G(60) of the reflective sheet at an incident angle of 60° and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: 15≤G(60)-G(85)≤22.

[0072] <18>

[0073] The optical component according to any one of <1> to <17>, wherein, The light guide plate includes a light incident surface and an opposite surface located between the light emitting surface and the back surface. The incident surface and the opposite surface are opposite each other in the first direction. The optical component also has a reflective layer overlapping the opposite surface.

[0074] <19>

[0075] A surface light source device, which further comprises: The optical component described in any one of <1> to <18>; and A light source that emits light incident on the light guide plate.

[0076] <20>

[0077] According to the surface light source device described in <19>, wherein... The difference in tilt angle (°) between the first element surface and the third element surface is greater than or equal to half the peak and half the width (°) of the angular distribution of brightness at the light-emitting surface.

[0078] <21>

[0079] A display device comprising: The surface light source device described in <19> or <20>; and The display panel faces the surface light source device.

[0080] <22>

[0081] A surface light source device, comprising: A light guide plate includes a light-emitting surface, a back surface facing the light-emitting surface, and a light-incident surface located between the light-emitting surface and the back surface; An optical sheet comprising a prism surface facing the light-emitting surface; The reflective sheet faces the back side; and The light source emits light that is incident on the light guide plate. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The optical sheet comprises a plurality of unit prisms arranged in the first direction. Each unit prism includes: a first prism surface located on a first side in the first direction; and a second prism surface facing the first prism surface from the first direction. The prism surface includes a first prism surface and a second prism surface. The first prism surface includes a first feature surface, a second feature surface, and a third feature surface. The second feature surface is located between the first feature surface and the third feature surface. The difference in tilt angle (°) between the first element surface and the third element surface is greater than or equal to half the peak and half the width (°) of the angular distribution of brightness at the light-emitting surface.

[0082] <23>

[0083] According to the surface light source device described in <22>, wherein, The spacing between the connecting surfaces in the first direction is larger than the spacing between the pixels of the display panel disposed facing the ground with the surface light source device in the first direction.

[0084] <24>

[0085] According to the surface light source device described in <22> or <23>, wherein, The spacing between the connecting surfaces in the first direction is 0.060 mm or more.

[0086] <25>

[0087] The surface light source device according to any one of <22> to <24>, wherein... The light guide plate includes a side opposite to the light incident surface in the first direction. The surface light source device also includes a reflective layer superimposed on the opposite surface.

[0088] <26>

[0089] A display device comprising: The surface light source device described in any one of <19> to <25>; and The display panel faces the surface light source device.

[0090] <27>

[0091] An optical component of a surface light source device is provided, which is an optical component of a surface light source device configured to be grounded facing a display panel, wherein... The optical component includes: A light guide plate comprising a light-emitting surface and a back surface facing the light-emitting surface; and An optical element comprising a prism surface facing the light-emitting surface. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The spacing between the connecting surfaces in the first direction is larger than the spacing between the pixels of the display panel in the first direction.

[0092] <28>

[0093] An optical component of a surface light source device, comprising: A light guide plate comprising a light-emitting surface and a back surface facing the light-emitting surface; and An optical element comprising a prism surface facing the light-emitting surface. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The spacing between the connecting surfaces in the first direction is 0.060 mm or more.

[0094] <29>

[0095] According to the optical component described in <27> or <28>, wherein, The light guide plate includes a light incident surface and an opposite surface located between the light emitting surface and the back surface. The incident surface and the opposite surface are opposite each other in the first direction. The optical component also has a reflective layer overlapping the opposite surface.

[0096] <30>

[0097] A surface light source device, comprising: The optical component described in any one of <27> to <29>; and A light source that emits light incident on the light guide plate.

[0098] <31>

[0099] A display device comprising: <30> The surface light source device; and The display panel faces the surface light source device.

[0100] <32>

[0101] An optical component of a surface light source device, comprising: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The reflective sheet, starting from the light guide plate, sequentially comprises a surface layer, an internal diffusion layer, and a metal layer. The internal diffusion layer comprises a base layer and a light-diffusing component retained within the base layer.

[0102] <33>

[0103] According to the optical component described in <32>, wherein... The reflective sheet has a specular gloss level of less than 200 at an incident angle of 20°. The reflective sheet has a specular gloss of 75 or higher at an incident angle of 85°.

[0104] <34>

[0105] An optical component of a surface light source device, comprising: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The reflective sheet has a specular gloss level of less than 200 at an incident angle of 20°. The reflective sheet has a specular gloss of 75 or higher at an incident angle of 85°.

[0106] <35>

[0107] The optical component according to any one of <32> to <34>, wherein... The specular gloss G(20) of the reflective sheet at an incident angle of 20°, the specular gloss G(60) of the reflective sheet at an incident angle of 60°, and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: |G(60)-G(85)|<|G(20)-G(60)|.

[0108] <36>

[0109] An optical component of a surface light source device, comprising: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The specular gloss G(20) of the reflective sheet at an incident angle of 20°, the specular gloss G(60) of the reflective sheet at an incident angle of 60°, and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: |G(60)-G(85)|<|G(20)-G(60)|.

[0110] <37>

[0111] The optical component according to any one of <32> to <36>, wherein... The specular gloss G(20) of the reflective sheet at an incident angle of 20°, the specular gloss G(60) of the reflective sheet at an incident angle of 60°, and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: |G(60)-G(85)| / ((G(60)+G(85)) / 2)<|G(20)-G(60)| / ((G(20)+G(60)) / 2).

[0112] <38>

[0113] An optical component of a surface light source device, comprising: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The specular gloss G(20) of the reflective sheet at an incident angle of 20°, the specular gloss G(60) of the reflective sheet at an incident angle of 60°, and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: |G(60)-G(85)| / ((G(60)+G(85)) / 2)<|G(20)-G(60)| / ((G(20)+G(60)) / 2).

[0114] <39>

[0115] The optical component according to any one of <32> to <38>, wherein... The diffuse reflectivity of the reflective sheet is above 65% and below 90%.

[0116] <40>

[0117] An optical component of a surface light source device, comprising: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The diffuse reflectivity of the reflective sheet is above 65% and below 90%.

[0118] <41>

[0119] The optical component according to any one of <32> to <40>, wherein... The reflective sheet has a specular gloss of 75 or higher at an incident angle of 85°.

[0120] <42>

[0121] An optical component of a surface light source device, comprising: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The reflective sheet has a specular gloss level of 75 or higher and 110 or lower at an incident angle of 85°.

[0122] <43>

[0123] The optical component according to any one of <32> to <42>, wherein... The ratio of the specular gloss of the reflective sheet at an incident angle of 85° to the specular gloss of the reflective sheet at an incident angle of 20° is 0.85 or higher.

[0124] <44>

[0125] An optical component of a surface light source device, comprising: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The ratio of the specular gloss of the reflective sheet at an incident angle of 85° to the specular gloss of the reflective sheet at an incident angle of 20° is 0.85 or higher.

[0126] <45>

[0127] The optical component according to any one of <32> to <44>, wherein... The specular gloss G(20) of the reflective sheet at an incident angle of 20° and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: G(20)-G(85)≤0.

[0128] <46>

[0129] An optical component of a surface light source device, comprising: A light guide plate, comprising a light-emitting surface and a back surface facing the light-emitting surface; and The reflective sheet faces the back side. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The specular gloss G(20) of the reflective sheet at an incident angle of 20° and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: G(20)-G(85)≤0.

[0130] <47>

[0131] The optical component of the surface light source device according to any one of <32> to <46>, wherein... The spacing between the connecting surfaces in the first direction is larger than the spacing between the pixels of the display panel disposed facing the ground with the surface light source device in the first direction.

[0132] <48>

[0133] The optical components of the surface light source device according to any one of <32> to <47>, wherein... The spacing between the connecting surfaces in the first direction is 0.060 mm or more.

[0134] <49>

[0135] The optical component according to any one of <32> to <48>, wherein... The ratio of the spacing of the connecting surface in the first direction to the spacing of the pixels of the display panel disposed facing the ground with the surface light source device in the first direction is 1.0 or more and 2.2 or less.

[0136] <50>

[0137] The optical component according to any one of <32> to <49>, wherein... The ratio of the specular gloss of the reflective sheet at an incident angle of 85° to the specular gloss of the reflective sheet at an incident angle of 60° is greater than 0.55 and less than 2.0.

[0138] <51>

[0139] The optical component according to any one of <32> to <50>, wherein... The specular gloss G(60) of the reflective sheet at an incident angle of 60° and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: 15≤G(60)-G(85)≤22.

[0140] <52>

[0141] The optical component according to any one of <32> to <51>, wherein... The light guide plate includes a light incident surface and an opposite surface located between the light emitting surface and the back surface. The incident surface and the opposite surface are opposite each other in the first direction. The optical component also has a reflective layer overlapping the opposite surface.

[0142] <53>

[0143] A surface light source device, which further comprises: The optical component described in any one of <32> to <52>; and A light source that emits light incident on the light guide plate.

[0144] <54>

[0145] A display device comprising: The surface light source device described in <53>; and The display panel faces the surface light source device.

[0146] Hereinafter, this embodiment will be described with reference to the accompanying drawings. Furthermore, in the drawings accompanying this specification, for ease of illustration and understanding, the scale and aspect ratios relative to the actual object have been appropriately altered and exaggerated. Structures shown in some figures may be omitted in others.

[0147] In this specification, terms such as “parallel,” “orthogonal,” “same,” or values ​​of length or angle used to describe shape, geometric conditions, and the degree to which they are determined are not limited to a strict meaning, but are interpreted to include the range of degrees to which the same function can be expected.

[0148] In this specification, the terms "sheet," "film," and "plate" are not distinguished solely by their different names. For example, "optical sheet" is not distinguished only by its name from components called optical films or optical plates. "Reflective sheet" is not distinguished only by its name from components called reflective films or reflective plates. "Light guide plate" is not distinguished only by its name from components called light guide sheets or light guide films.

[0149] In this specification, the normal direction of a sheet-like (sheet-like, plate-like) component refers to the direction parallel to the normal or perpendicular line of the sheet-like (film-like, plate-like) surface of the object. "Sheet surface (film surface, plate surface)" refers to the surface whose plane direction coincides with that of the object when the sheet-like (film-like, plate-like) component is viewed as a whole.

[0150] In this specification, when multiple candidate upper limits and multiple candidate lower limits are listed for a certain parameter, the numerical range of that parameter can also be constructed by combining any candidate upper limit and any candidate lower limit. As an example, let's examine the statement: "Parameter B can be above A1, above A2, or above A3. Parameter B can be below A4, below A5, or below A6." In this example, the numerical range of parameter B can be above A1 and below A4, above A1 and below A5, above A1 and below A6, above A2 and below A4, above A2 and below A5, above A2 and below A6, above A3 and below A4, above A3 and below A5, or above A3 and below A6.

[0151] To clarify the directional relationships between the figures, the first direction D1, the second direction D2, and the third direction D3 are shown as common directions in several figures using arrows labeled with the same number. The end of the arrow represents the first side of each direction. The side opposite to the end of the arrow represents the second side of each direction. For example... Figure 1 As shown, the dot notation within the circle represents an arrow pointing forward from the paper in a direction orthogonal to the plane of the paper in the attached figure.

[0152] "Inhibition" refers to suppressing or hindering the realization or occurrence of something. "Inhibition" not only means completely preventing the realization or occurrence of something, but also means reducing the likelihood of the realization or occurrence of something, or making it difficult to cause the realization or occurrence of something.

[0153] Figures 1 to 13This is a diagram used to illustrate this embodiment. The surface light source device 20 may also include an optical component 28 and a light source 24. The optical component 28 adjusts the optical path of the light emitted from the light source 24. The surface light source device 20 includes a light-emitting surface 21. Light is emitted from the light-emitting surface 21. Figure 1 A display device 10 is shown in schematic form as an application example of a surface light source device 20 and an optical component 28.

[0154] Hereinafter, this embodiment will be described using an example of applying the surface light source device 20 and the optical component 28 to the display device 10. In this embodiment, the effective widening of the viewing angle in the display device 10 using the surface light source device 20 and the optical component 28 was studied. However, the surface light source device 20 and the optical component 28 are not limited to application in the display device 10. The surface light source device 20 and the optical component 28 can be applied to various applications such as lighting devices.

[0155] like Figure 1 As shown, the display device 10 may include a display panel 15 and a surface light source device 20. In the illustrated example, the display panel 15 and the surface light source device 20 may also overlap in a third direction D3. The third direction D3 may also be a stacking direction. The third direction D3 may also be the thickness direction of the display panel 15 and the surface light source device 20. The third direction D3 may also be the thickness direction of each component included in the display panel 15 and the surface light source device 20. The display panel 15 and the surface light source device 20 may also extend in a direction orthogonal to the third direction D3.

[0156] In the illustrated example, the liquid crystal display panel 15 and the surface light source device 20 extend along the first direction D1 and the second direction D2. The illustrated liquid crystal display panel 15 and surface light source device 20 are flat. The first direction D1 and the second direction D2 are orthogonal. The third direction D3 is orthogonal to the first direction D1. The third direction D3 is orthogonal to the second direction D2. Viewed from the third direction towards D3, the illustrated liquid crystal display panel 15 and surface light source device 20 have a rectangular shape. Viewed from the third direction towards D3, the illustrated liquid crystal display panel 15 and surface light source device 20 have a pair of end edges extending along the first direction D1 and the second direction D2, respectively.

[0157] In the illustrated example, the first direction D1 can also be a vertical direction. In the illustrated example, the first side on the first direction D1 can also be the upper side in the vertical direction. In the illustrated example, the second direction D2 and the third direction D3 can each be along a horizontal direction. In the illustrated example, the normal direction of the display panel 15 is parallel to the third direction D3, and the normal direction of the surface light source device 20 is parallel to the third direction D3. In the illustrated example, the display surface 11 is perpendicular to the third direction D3, and the light-emitting surface 21 of the surface light source device 20 (described later) is orthogonal to the third direction D3. In the illustrated example, the reflector 70, light guide plate 30, and optical sheet 50 included in the surface light source device 20 and optical components 28 are orthogonal to the third direction D3.

[0158] Display panel 15 can also constitute display surface 11. The normal direction of display surface 11 can also be parallel to the third direction D3. Images can also be displayed on display surface 11. Figure 1 In the example shown, the surface light source device 20 illuminates the display panel 15 from behind as a backlight. The display panel 15 can also be a transmissive display panel. The display panel 15 can also be a liquid crystal display (LCD) panel. There is no particular limitation on the type of LCD panel. The display panel 15 can be a TN type LCD panel, a VA type LCD panel, or an IPS type LCD panel. The display panel 15 can also contain multiple pixels 16. The display panel 15 functions as a shutter that controls the transmission or blocking of light from the surface light source device 20 according to each pixel. A pixel becomes the smallest unit constituting an image.

[0159] Figure 2 A specific example of the pixel arrangement in a display panel 15 is shown. The illustrated display panel 15 includes a first pixel 16A, a second pixel 16B, and a third pixel 16C.

[0160] exist Figure 2 In the example shown, the first pixel 16A, the second pixel 16B, and the third pixel 16C are repeatedly arranged in this order on the second direction D2. Figure 2 In the example shown, the first pixel 16A is continuously arranged in the first direction D1. Figure 2 In the example shown, the second pixel 16B is continuously arranged in the first direction D1. Figure 2 In the example shown, the third pixel 16C is continuously arranged in the first direction D1. Figure 2 In the example shown, pixels 16A, 16B, and 16C are arranged with a first pixel spacing PP1 in the first direction D1. Pixels 16A, 16B, and 16C are arranged with a second pixel spacing PP2 in the second direction D2.

[0161] The first pixel 16A, the second pixel 16B, and the third pixel 16C can also emit image light of different colors. The first pixel 16A can also emit blue image light. The second pixel 16B can also emit green image light. The third pixel 16C can also emit red image light. A unit pixel can also be formed by a first pixel 16A, a second pixel 16B, and a third pixel 16C arranged consecutively in the second direction D2. Figure 2 A unit pixel is illustrated by being surrounded by a dashed line. The first pixel 16A, the second pixel 16B, and the third pixel 16C can also each constitute a sub-pixel.

[0162] like Figure 3 As shown, the surface light source device 20 includes a light source 24 and an optical component 28. The optical component 28 adjusts the light path of the light emitted from the light source 24. The optical component 28 may also form a light-emitting surface 21. In this embodiment, the surface light source device 20 may also be configured as an edge-lit type. The light emitted from the light source 24, i.e., the light from the light source, may also be incident on the optical component 28 from the side. That is, the light may also be incident on the optical component 28 from a direction that is not parallel to the third direction D3, for example, a direction orthogonal to the third direction D3.

[0163] like Figure 3 As shown, the optical component 28 may also include a reflector 70, a light guide plate 30, and an optical sheet 50. The reflector 70, the light guide plate 30, and the optical sheet 50 may also be stacked sequentially in the third direction D3. That is, the light guide plate 30 may also be located between the reflector 70 and the optical sheet 50 in the third direction D3.

[0164] In the illustrated example, the reflector 70, light guide plate 30, and optical sheet 50 extend in the first direction D1 and the second direction D2. The reflector 70, light guide plate 30, and optical sheet 50 illustrated are flat. Figure 4 The reflector 70, light guide plate 30, and optical sheet 50 shown have a rectangular shape when viewed from a third direction (D3). When viewed from a third direction (D3), the reflector 70, light guide plate 30, and optical sheet 50 have a pair of end edges extending in a first direction (D1) and a second direction (D2), respectively. Figure 4 In the example shown, the light emitted from the light source 24 is incident from the second lateral optical component 28 in the first direction D1.

[0165] The light source 24 is not particularly limited. For example, the light source 24 may include fluorescent lamps such as linear cold cathode tubes, point-shaped LEDs (light-emitting diodes), or incandescent lamps. Figure 4As shown, the light source 24 may also include a plurality of dot-shaped light emitters 25 arranged in the second direction D2. The light emitters 25 may also be light-emitting diodes (LEDs). The light emitters 25 may also face the optical component 28 from the side. The light emitters 25 may also be arranged facing the light guide plate 30. Alternatively, the light emitted from the light emitters 25 may also be guided to the optical component 28 by a reflective component or the like.

[0166] like Figure 5 As shown, the light guide plate 30 is plate-shaped. The light guide plate 30 may also include a light-emitting surface 31 and a back surface 32 as a pair of main surfaces. The light-emitting surface 31 may also face a first side in the first direction D1. The light-emitting surface 31 may also face the optical sheet 50. The back surface 32 may also face a second side in the first direction D1. The back surface 32 may also face the reflective sheet 70. The light guide plate 30 may also include a side surface located between the light-emitting surface 31 and the back surface 32. The side surface of the light guide plate 30 may also face a direction orthogonal to a third direction D3.

[0167] The light guide plate 30 may also include a light incident surface 33 facing a second side in the first direction D1 as a side surface. Light from the light source can also be incident on the light guide plate 30 through the light incident surface 33. The light emitter 25 may also be arranged facing the light incident surface 33. Figure 5 The light-incident surface 33 shown is positioned opposite to the light-emitting element 25 constituting the light source 24. Light from the light-incident surface 33 enters the light guide plate 30 and travels within the light guide plate 30 in a first direction D1, opposite to the light-incident surface 33. In the illustrated example, the light guide plate 30 also includes a first side surface 35a and a second side surface 35b as sides. The first side surface 35a and the second side surface 35b extend between the light-incident surface 33 and the opposite side surface 34, respectively.

[0168] The light guide plate 30 guides the light from the light source incident from the light incident surface 33 primarily in the first direction D1. The material constituting the light guide plate 30 can also be a transparent material, such as a transparent resin material. "Transparent" means that the total transmittance is 50% or more and 100% or less; it can be 80% or more and 100% or less, or 90% or more and 100% or less. The total transmittance is a value measured according to JIS K7361-1:1997. The incident angle is set to 0° when measuring the total transmittance. The incident angle is the angle (°) formed by the direction of travel of the incident light relative to the normal direction of the sheet-like component into which the light is incident. An incident angle is an angle of 0° or more and 90° or less. The measurement environment for measuring the total transmittance is set as follows: temperature 23℃±2℃, relative humidity 50%±5%. Before the test begins, the sample to be measured is placed in the measurement environment for 16 hours. Before measuring the total transmittance, turn on the light source of the measuring device for 15 minutes to stabilize the output of the light source.

[0169] like Figure 5and Figure 6 As shown, the back surface 32 can also be configured as a concave-convex surface. The back surface 32 can also include multiple inclined surfaces 37 and multiple connecting surfaces 39. For example... Figure 5 and Figure 6 As shown, the inclined surface 37 and the connecting surface 39 can also be arranged alternately along the first direction D1.

[0170] In the illustrated example, the inclined surface 37 is inclined relative to the first direction D1, such that its first side in the first direction D1 approaches the light-emitting surface 31. That is, the distance between the light-emitting surface 31 and the inclined surface 37 along the third direction D3 gradually shortens towards the first side in the first direction D1. Light guiding within the light guide plate 30 is achieved based on total internal reflection at a pair of principal surfaces of the light guide plate 30, namely the light-emitting surface 31 and the back surface 32. However, by reflecting off the inclined surface 37, the angle of incidence when incident on the pair of principal surfaces 31, 32 becomes smaller. By reflecting off the inclined surface 37, if the angle of incidence to the pair of principal surfaces 31, 32 is less than the critical angle of total internal reflection, the light can be emitted from the light guide plate 30. The inclined surface 37 functions as a light extraction element for extracting light from the light guide plate 30.

[0171] The connecting surface 39 can be inclined to the opposite side of the inclined surface 37 with the third direction D3 as the center, or it can extend along the third direction D3. By arranging the connecting surface 39 between two adjacent inclined surfaces 37, the thickness variation of the light guide plate 30 at various positions in the first direction D1 can be reduced.

[0172] In addition to the inclined surface 37 and the connecting surface 39, the back surface 32 may also include a flat surface 38. The angle between the first direction D1 and the flat surface 38 may also be smaller than the angle between the first direction D1 and the inclined surface 37. Similarly, the angle between the first direction D1 and the flat surface 38 may be smaller than the angle between the first direction D1 and the connecting surface 39. Figure 3 and Figure 6 As shown, the flat surface 38 can also be parallel to the first direction D1. By setting the flat surface 38, the distribution of the inclined surface 37 along the first direction D1, which is the light guiding direction, can be adjusted. By adjusting the distribution of the inclined surface 37, the distribution of the amount of light emitted from the light guide plate 30 along the first direction D1 can be adjusted.

[0173] The angle between the first direction D1 and the inclined surface 37 refers to the angle between the first direction D1 and the inclined surface 37 in the cross section along the first direction and the third direction D3. The angle between the first direction D1 and the flat surface 38 refers to the angle between the first direction D1 and the flat surface 38 in the cross section along the first direction and the third direction D3. The angle between the first direction D1 and the connecting surface 39 refers to the angle between the first direction D1 and the connecting surface 39 in the cross section along the first direction and the third direction D3. These angles are set to be greater than 0° and less than 90°. Figure 6 The angle θy between the first direction D1 and the inclined surface 37 is shown in the figure.

[0174] The tilt angle θy of the tilted surface 37 relative to the first direction D1 can be 0.10° or more, 1.0° or more, or 1.5° or more. The tilt angle θy is the angle between the first direction D1 and the tilted surface 37. By setting a lower limit for the tilt angle θy, the light extraction efficiency from the light guide plate 30 can be improved. The tilt angle θy of the tilted surface 37 relative to the first direction D1 can be 5.0° or less, 3.0° or less, or 2.0° or less. By setting an upper limit for the tilt angle θy, the direction of travel of light emitted from the light-emitting surface 31 of the light guide plate 30 can be limited to a narrower angular range. The tilted surface 37 can also be a flat surface. The tilt angle θy of each tilted surface 37 can also be constant within the tilted surface 37. The tilted surface 37 can also include a curved surface. The tilted surface 37 can also include a folded surface. The tilt angle θy of the tilted surface 37 containing a curved surface or a folded surface is set as the tilt angle measured at the center position in the first direction D1.

[0175] The angle θy of the inclined surface can be greater than 0.10° and less than 5.0°, greater than 1.0° and less than 5.0°, or greater than 1.5° and less than 5.0°. The angle θy of the inclined surface can be greater than 0.10° and less than 3.0°, greater than 1.0° and less than 3.0°, or greater than 1.5° and less than 3.0°. The angle θy of the inclined surface can be greater than 0.10° and less than 2.0°, greater than 1.0° and less than 2.0°, or greater than 1.5° and less than 2.0°.

[0176] exist Figure 3 In the example shown, as the light guide direction D1 moves from the incident surface 33 towards the opposite surface 34, that is, from the second side to the first side in the first direction D1, the proportion of the inclined surface 37 on the back surface 32 increases. According to this structure, the emission of light from the light guide plate 30 in the region away from the incident surface 33 along the light guide direction can be promoted. Therefore, the decrease in the amount of emitted light as it moves away from the incident surface 33 can be suppressed. The illuminance distribution along the first direction D1 on the emitting surface 31 can be made more uniform.

[0177] like Figure 5 As shown, the inclined surface 37 can also extend in the second direction D2. The angle θy between the inclined surface 37 and the first direction D1 can also be constant at various positions in the second direction D2. The connecting surface 39 can also extend in the second direction D2. The angle between the connecting surface 39 and the first direction D1 can also be constant at various positions in the second direction D2. The flat surface 38 can also extend in the second direction D2. The angle θy between the flat surface 38 and the first direction D1 can also be constant at various positions in the second direction D2.

[0178] Flat surface 38 is adjacent to inclined surface 37. For example... Figure 3 and Figure 6 As shown, the flat surface 38 can also be connected to the inclined surface 37 from a second side in the first direction D1. The flat surface 38 can also be connected to the inclined surface 37 from a first side in the first direction D1. The flat surface 38 can also be connected to the inclined surface 37 from both sides in the first direction D1. The flat surface 38 can be connected to the inclined surface 37 from a constant side in the first direction D1, or it can be connected to the inclined surface 37 from a side other than a constant side in the first direction D1. Figure 3 and Figure 6 As shown, the end of the inclined surface 37 on the first side in the first direction D1 can also appear in the first direction D1 with a constant period. Figure 3 and Figure 6 As shown, the end of the first side of the connecting surface 39 in the first direction D1 can also appear in the first direction D1 with a constant period.

[0179] The arrangement spacing PC of the connecting surfaces 39 in the first direction D1 can also be longer than before. By setting a lower limit for the arrangement spacing PC of the connecting surfaces 39 in the first direction D1, the generation of stray light and the like can be suppressed, thereby improving the utilization efficiency of the light source. The arrangement spacing PC of the connecting surfaces 39 in the first direction D1 can be 0.060 mm or more, 0.070 mm or more, 0.080 mm or more, or 0.20 mm or more. The arrangement spacing PC of the connecting surfaces 39 in the first direction D1 can be 0.37 mm or less, 0.32 mm or less, or 0.28 mm or less. By setting an upper limit for the arrangement spacing PC of the connecting surfaces 39 in the first direction D1, the observation of unevenness on the back surface 32 can be suppressed.

[0180] The arrangement spacing PC can be 0.060mm or more and 0.37mm or less, 0.070mm or more and 0.37mm or less, 0.080mm or more and 0.37mm or less, or 0.20mm or more and 0.37mm or less. The arrangement spacing PC can be 0.060mm or more and 0.32mm or less, 0.070mm or more and 0.32mm or less, 0.080mm or more and 0.32mm or less, or 0.20mm or more and 0.32mm or less. The arrangement spacing PC can be 0.060mm or more and 0.28mm or less, 0.070mm or more and 0.28mm or less, 0.080mm or more and 0.28mm or less, or 0.20mm or more and 0.28mm or less.

[0181] The arrangement spacing PC (mm) of the connecting surface 39 in the first direction D1 can also be greater than the arrangement spacing PP1 (mm) of the pixels 16 in the first direction D1. In this way, by extending the arrangement spacing PC of the connecting surface 39 in the first direction D1, the generation of stray light and the like can be suppressed, thereby improving the utilization efficiency of the light source.

[0182] The ratio of the arrangement spacing PC (mm) of the connecting surface 39 in the first direction D1 to the arrangement spacing PP1 (mm) of the pixels 16 in the first direction D1 can be 0.60 or more, 1.0 or more, 1.2 or more, or 1.4 or more. By setting a lower limit for this ratio, the generation of stray light can be suppressed, thereby improving the utilization efficiency of the light source. The ratio of the arrangement spacing PC (mm) of the connecting surface 39 in the first direction D1 to the arrangement spacing PP1 (mm) of the pixels 16 in the first direction D1 can be 2.2 or less, 2.0 or less, 1.9 or less, or 1.8 or less. By setting an upper limit for this ratio, the observation of unevenness on the back surface 32 can be suppressed. By setting an upper limit for this ratio, the moiré fringes caused by the interference between the regularity of the structure on the back surface 32 and the regularity of the pixels can be made less noticeable.

[0183] The ratio of the arrangement spacing PC (mm) to the arrangement spacing PP1 (mm) can be 0.60 or higher and 2.2 or lower, 1.0 or higher and 2.2 or lower, 1.2 or higher and 2.2 or lower, or 1.4 or higher and 2.2 or lower. The ratio of the arrangement spacing PC (mm) to the arrangement spacing PP1 (mm) can be 0.60 or higher and 2.0 or lower, 1.0 or higher and 2.0 or lower, 1.2 or higher and 2.0 or lower, or 1.4 or higher and 2.0 or lower. The ratio of the arrangement spacing PC (mm) to the arrangement spacing PP1 (mm) can be 0.60 or higher and 1.9 or lower, 1.0 or higher and 1.9 or lower, 1.2 or higher and 1.9 or lower, or 1.4 or higher and 1.9 or lower. The ratio of the arrangement spacing PC (mm) to the arrangement spacing PP1 (mm) can be greater than 0.60 and less than 1.8, greater than 1.0 and less than 1.8, greater than 1.2 and less than 1.8, or greater than 1.4 and less than 1.8.

[0184] As an example, other dimensions of the light guide plate 30 can also be set as follows: The length of the light guide plate 30 in the third direction D3, i.e., the thickness of the light guide plate 30, can be 0.10 mm or more, 0.20 mm or more, or 0.30 mm or more. The length of the light guide plate 30 in the third direction D3 can be less than 1.0 mm, more than 0.9 mm, or less than 0.7 mm. The length of the light guide plate 30 in the first direction D1 and the length of the light guide plate 30 in the second direction D2 are not particularly limited. The length of the light guide plate 30 in the first direction D1 and the length of the light guide plate 30 in the second direction D2 can, for example, be determined based on the size of the display device.

[0185] The light guide plate 30 can be manufactured using extrusion molding, UV molding, injection molding, etc. Various materials can be used as the material for the light guide plate 30. The material of the light guide plate 30 can also be a transparent resin with one or more of the following as its main components: acrylic resin, polystyrene resin, polycarbonate resin, polyethylene terephthalate resin, polyacrylonitrile resin, etc. The light guide plate 30 may also contain a resin material matrix and a light-diffusing component dispersed in the matrix. The light-diffusing component can also be inorganic particles such as silica or alumina. Alternatively, it can be organic particles such as acrylic resin, polycarbonate resin, or silicone resin.

[0186] like Figure 7As shown, the optical sheet 50 is plate-shaped. The optical sheet 50 may also include a first surface 51 and a second surface 52 as a pair of main surfaces. The first surface 51 may also face a first side on the third direction D3. The second surface 52 may also face a second side on the third direction D3. The second surface 52 may also face the light guide plate 30. The second surface 52 is configured as a prism surface 53.

[0187] The optical sheet 50 may also include a main body 55 and a unit prism 60. The main body 55 may also be sheet-like. The main body 55 may also include a light-emitting side 55a and a light-incident side 55b. As shown in the example, the light-emitting side 55a of the main body 55 may also constitute the first surface 51 of the optical sheet 50. The first surface 51 may also be a surface orthogonal to the third direction D3.

[0188] The first surface 51 can be a flat surface. The first surface 51 can also be a matte surface. The first surface 51 can also be a textured surface. For the purpose of adjusting the amount of light or the brightness in the second direction, the first surface 51 can also be composed of linear protrusions or linear concave portions along the first direction. The linear protrusions or linear concave portions along the first direction can also be arranged along the second direction D2.

[0189] Multiple unit prisms 60 may also be provided on the light-incident side 55b of the main body 55. Alternatively, multiple unit prisms 60 may be provided without gaps on the light-incident side 55b of the main body 55. Multiple unit prisms 60 may also constitute the second surface 52 of the optical sheet 50. The prism surface 53 may also be composed of multiple unit prisms 60.

[0190] A "unit prism" is an element that functions by applying optical effects such as refraction or reflection to light, thereby changing the direction of light travel. A "unit prism" is not distinguished solely by its name from "unit shape element," "unit optical element," or "unit lens."

[0191] Multiple unit prisms 60 can also be arranged along the first direction D1. Each unit prism 60 can also extend in a linear fashion. For example... Figure 7 As shown in the example, each unit prism 60 can also extend in a straight line. For example... Figure 7 As shown in the example, each unit prism 60 can also extend linearly in a second direction D2 orthogonal to the arrangement direction, i.e., the first direction D1. For example... Figure 7 As shown in the example, multiple unit prisms 60 can also form a linear array prism. Each unit prism 60 can also be cylindrical.

[0192] The arrangement of multiple unit prisms 60 is not limited to Figure 7The example shown. Multiple unit prisms 60 can also be arranged in two or more directions, including the first direction D1 and directions not parallel to the first direction D1. Multiple unit prisms 60 can also form a two-dimensional array of microlenses.

[0193] Each unit prism 60 may also include a first prism surface 61 and a second prism surface 62. The first prism surface 61 and the second prism surface 62 may also face each other in the first direction D1. The first prism surface 61 may also be located on a first side in the first direction D1. The second prism surface 62 may also be located on a second side in the first direction D1. Prism surface 53 may also include a first prism surface 61 and a second prism surface 62. Prism surface 53 may also be composed only of the first prism surface 61 and the second prism surface 62. As will be described later, the second prism surface 62 can function as an incident surface for light emitted from the light guide plate 30. The first prism surface 61 can function as a reflective surface for reflecting light traveling within the unit prism 60 through the second prism surface 62.

[0194] like Figure 8 As shown in the example, the first prism surface 61 and the second prism surface 62 can also extend from the main body portion 55, respectively. The first prism surface 61 and the second prism surface 62 can also be connected to the main body portion 55 at one end. Figure 8 As shown in the example, the first prism surface 61 and the second prism surface 62 can also be connected to each other at the other end. The first prism surface 61 and the second prism surface 62 can also form the top 63 of the unit prism 60, which is furthest from the main body 55 in the third direction D3, at the other end.

[0195] In the illustrated example, in the main cross-section of the optical plate 50 parallel to both the first direction D1 and the third direction D3, the first prism surface 61 and the second prism surface 62 approach each other as they move away from the main body 55. Figure 8 In the main cross-section of the optical plate 50 shown, the unit prism 60 has a cross-sectional shape that tapers at the ends. Figure 7 In the example shown, the cross-sectional shape of the optical sheet 50 is constant at all positions in the second direction D2 in the principal section. The illustrated unit prism 60 extends in the second direction D2 with a constant cross-sectional shape. In the illustrated optical sheet 50, multiple unit prisms 60 have the same structure. Not limited to the illustrated example, the multiple unit prisms 60 may also have different structures. Not limited to the illustrated example, the cross-sectional shape of each unit prism 60 may also differ at various positions in the second direction D2.

[0196] like Figure 8As shown, the first prism surface 61 can also be a folded surface. The first prism surface 61 can also include a first element surface 66, a second element surface 67, and a third element surface 68. The first element surface 66, the second element surface 67, and the third element surface 68 can also be connected sequentially. The first element surface 66, the second element surface 67, and the third element surface 68 can also be arranged sequentially from the top 63 of the unit prism 60 towards the base end. The second element surface 67 can be located between the first element surface 66 and the third element surface 68. The first element surface 66 can also form the top 63 at one end. The first element surface 66 can also be connected to one end of the second element surface 67 at the other end. The second element surface 67 can also be connected to one end of the third element surface 68 at the other end. The third element surface 68 can also be connected to the main body 55 at the other end. (Not limited to...) Figure 8 In the example shown, the first prism surface 61 can also contain more than four feature surfaces.

[0197] The angle between the prism surface or feature surface and the stacking direction (third direction D3) of the constituent elements of the optical component 28 is set as the tilt angle θx (°). The tilt angle θx (°) is an angle between 0° and 90°. The tilt angle of the prism surface or feature surface containing a curved surface is the angle measured at the center position in the first direction D1 of the prism surface or feature surface. The tilt angle of the feature surface included in the first prism surface 61 may also decrease as the position of the feature surface approaches the main body 55 from the top 63. In the illustrated example, the tilt angle θxe1 of the first feature surface 66 may also be greater than the tilt angle θxe2 of the second feature surface 67. The tilt angle θxe2 of the second feature surface 67 may be greater than the tilt angle θxe3 of the third feature surface 68. According to this structure, the entire area of ​​the first prism surface 61 can be effectively used to implement optical path adjustment.

[0198] A lower limit can be set for the tilt angle difference (°) between the first element surface 66 and the third element surface 68. That is, a lower limit can also be set for the tilt angle difference (°) between the tilt angles θxe1 and θxe3 of the first element surface. By setting a lower limit for the tilt angle difference (°), light incident from the light guide plate 30 onto the optical sheet 50 can be diffused by reflection on the first prism surface 61. As a result, the viewing angle of the display device 10 can be effectively expanded. An upper limit can also be set for the tilt angle difference (°) between the first element surface 66 and the third element surface 68. By setting an upper limit for the tilt angle difference (°), excessive diffusion can be suppressed. As a result, the light source light can be utilized efficiently in the image formation of the display device 10. The tilt angle difference (°) between the first element surface 66 and the third element surface 68 can be 5° or more, 8° or more, 10° or more, or 12° or more. The difference in tilt angle (°) between the first element plane 66 and the third element plane 68 can be less than 20°, less than 18°, or less than 15°.

[0199] The difference in tilt angle (°) between the first element surface 66 and the third element surface 68 can be 5° or more and 20° or less, 8° or more and 20° or less, 10° or more and 20° or less, or 12° or more and 20° or less. The difference in tilt angle (°) between the first element surface 66 and the third element surface 68 can be 5° or more and 18° or less, 8° or more and 18° or less, 10° or more and 18° or less, or 12° or more and 18° or less. The difference in tilt angle (°) between the first element surface 66 and the third element surface 68 can be 5° or more and 15° or less, 8° or more and 15° or less, 10° or more and 15° or more, or 12° or more and 15° or less.

[0200] The difference in tilt angle (°) between the first element surface 66 and the third element surface 68 can be greater than twice, 2.5 times, three times, four times, or even six times the tilt angle θy of the tilt surface 37 relative to the first direction D1. According to this example, the difference in tilt angle (°) can be sufficiently increased relative to the deviation of the direction of light travel emitted from the light guide plate 30. Therefore, light incident from the light guide plate 30 onto the optical sheet 50 can be diffused by reflection on the first prism surface 61. This effectively expands the viewing angle of the display device 10.

[0201] The utilization efficiency of the light source can also be considered to set an upper limit for the tilt angle difference (°) between the first element surface 66 and the third element surface 68. The tilt angle difference (°) between the first element surface 66 and the third element surface 68 can be greater than twice and less than 15 times the tilt angle θy of the tilt surface 37 relative to the first direction D1, or greater than 2.5 times and less than 15 times, or greater than 3 times and less than 15 times, or greater than 4 times and less than 15 times, or greater than 6 times and less than 15 times.

[0202] The angle difference (°) between the first element surface 66 and the third element surface 68 can also be greater than half the peak and half the width (°) of the angular distribution of brightness at the light-emitting surface 31 of the light guide plate 30. According to this example, the angle difference (°) is sufficiently large relative to the deviation of the direction of travel of the light emitted from the light guide plate 30. Therefore, the light incident on the optical sheet 50 from the light guide plate 30 can be diffused by reflection on the first prism surface 61. This effectively expands the viewing angle of the display device 10.

[0203] The angle difference (°) between the first element surface 66 and the third element surface 68 can be greater than or less than 20° in the half-peak and half-width (°) of the brightness angle distribution at the light-emitting surface 31 of the light guide plate 30, or greater than or less than 18°, or greater than or less than 15°.

[0204] Here, the angular distribution of brightness at the light-emitting surface 31 of the light guide plate 30 is the brightness (cd / m²) in each direction within the surface, including the third direction D3 (which is the stacking direction of the light guide plate 30 and the optical sheet 50) and the first direction D1. 2 The related distribution. As an example, such as Figure 10 The diagram illustrates the relationship between brightness and the angle (°) between the direction from which the brightness is obtained and the third direction D3. When the direction from which the brightness is obtained is tilted relative to the third direction D3 towards the first direction D1, the angle (°) between this direction and the third direction D3 is a positive value. That is, the angle on the horizontal axis is the positive value of the brightness emitted from the light-emitting surface 31 in the direction tilted from the third direction D3 towards the first direction D1. The brightness angle distribution at the light-emitting surface 31 is a measurement taken after removing components that are closer to the light-emitting surface 21 than the surface light source device 20. Figure 3 In the surface light source device 20 shown, the measured value is set as that in the device including the light source 24, the light guide plate 30 and the reflector 70. Half-peak half-width HW (°) refers to the angle (°) between the following two directions: the direction between the direction where the maximum brightness BMAX is obtained and the third direction D3, and the direction where the brightness BF is half of the maximum brightness BMAX; and the direction where the maximum brightness BMAX is obtained.

[0205] Luminance in angular distribution (cd / m) 2 This can be measured using the ELDIM EZ Contrast XL80. For Figure 10 The angular distribution of brightness shown was measured using an EZ Contrast XL80 from ELDIM.

[0206] The tilt angle θxe1 of the first element surface can be greater than 25° and less than 55°, greater than 30° and less than 55°, or greater than 35° and less than 55°. The tilt angle θxe1 of the first element surface can be greater than 25° and less than 50°, greater than 30° and less than 50°, or greater than 35° and less than 50°. The tilt angle θxe1 of the first element surface can be greater than 25° and less than 45°, greater than 30° and less than 45°, or greater than 35° and less than 45°.

[0207] The tilt angle θxe2 of the second element surface can be greater than 19° and less than 49°, greater than 24° and less than 49°, or greater than 29° and less than 49°. The tilt angle θxe2 of the second element surface can be greater than 19° and less than 44°, greater than 24° and less than 44°, or greater than 29° and less than 44°. The tilt angle θxe2 of the second element surface can be greater than 19° and less than 39°, greater than 24° and less than 39°, or greater than 29° and less than 39°.

[0208] The tilt angle θxe3 of the third element surface can be greater than 12° and less than 42°, greater than 17° and less than 42°, or greater than 22° and less than 42°. The tilt angle θxe3 of the third element surface can be greater than 12° and less than 37°, greater than 17° and less than 37°, or greater than 22° and less than 37°. The tilt angle θxe3 of the third element surface can be greater than 12° and less than 32°, greater than 17° and less than 32°, or greater than 22° and less than 32°.

[0209] The tilt angle θx2 of the second prism surface 62 can be greater than 20° and less than 50°, greater than 25° and less than 50°, or greater than 30° and less than 50°. The tilt angle θx2 of the second prism surface 62 can be greater than 20° and less than 45°, greater than 25° and less than 45°, or greater than 30° and less than 45°. The tilt angle θx2 of the second prism surface 62 can be greater than 20° and less than 40°, greater than 25° and less than 40°, or greater than 30° and less than 40°.

[0210] The length Wx of the unit prism 60 in the first direction D1 can be 12 μm or more and 32 μm or less, 14 μm or more and 32 μm or less, or 16 μm or more and 32 μm or less. The length Wx of the unit prism 60 in the first direction D1 can be 12 μm or more and 30 μm or less, 14 μm or more and 30 μm or less, or 16 μm or more and 30 μm or less. The length Wx of the unit prism 60 in the first direction D1 is equivalent to the width Wx of the unit prism 60.

[0211] The ratio (Wx1 / Wx) of the length Wx1 of the first prism surface 61 in the first direction D1 to the length Wx of the unit prism 60 in the first direction D1 can be greater than or equal to 0.32 and less than 0.62, greater than or equal to 0.37 and less than 0.62, or greater than or equal to 0.42 and less than 0.62. The ratio (Wx1 / Wx) can be greater than or equal to 0.32 and less than 0.57, greater than or equal to 0.37 and less than 0.57, or greater than or equal to 0.42 and less than 0.52.

[0212] The ratio (Wxe1 / Wx) of the length Wxe1 of the first element surface 66 in the first direction D1 to the length Wx of the unit prism 60 in the first direction D1 can be greater than or equal to 0.050 and less than 0.17, greater than or equal to 0.070 and less than 0.17, or greater than or equal to 0.090 and less than 0.17. The ratio (Wxe1 / Wx) can be greater than or equal to 0.050 and less than 0.15, greater than or equal to 0.070 and less than 0.15, or greater than or equal to 0.090 and less than 0.15. The ratio (Wxe1 / Wx) can be greater than or equal to 0.050 and less than 0.13, greater than or equal to 0.070 and less than 0.13, or greater than or equal to 0.090 and less than 0.13.

[0213] The ratio (Wxe2 / Wx) of the length Wxe2 of the second element surface 67 in the first direction D1 to the length Wx of the unit prism 60 in the first direction D1 can be greater than or equal to 0.080 and less than 0.20, greater than or equal to 0.10 and less than 0.20, or greater than or equal to 0.12 and less than 0.20. The ratio (Wxe2 / Wx) can be greater than or equal to 0.080 and less than 0.18, greater than or equal to 0.10 and less than 0.18, or greater than or equal to 0.12 and less than 0.18. The ratio (Wxe2 / Wx) can be greater than or equal to 0.080 and less than 0.16, greater than or equal to 0.10 and less than 0.16, or greater than or equal to 0.12 and less than 0.16.

[0214] The ratio (Wxe3 / Wx) of the length Wxe3 of the third element surface 68 in the first direction D1 to the length Wx of the unit prism 60 in the first direction D1 can be greater than 0.16 and less than 0.28, greater than 0.18 and less than 0.28, or greater than 0.20 and less than 0.28. The ratio (Wxe3 / Wx) can be greater than 0.16 and less than 0.26, greater than 0.18 and less than 0.26, or greater than 0.20 and less than 0.26. The ratio (Wxe3 / Wx) can be greater than 0.16 and less than 0.24, greater than 0.18 and less than 0.24, or greater than 0.20 and less than 0.24.

[0215] The length Hx of the unit prism 60 in the third direction D3 can be greater than 8.0 μm and less than 20 μm, greater than 10 μm and less than 20 μm, or greater than 12 μm and less than 20 μm. The length Hx of the unit prism 60 in the third direction D3 can be greater than 8.0 μm and less than 18 μm, greater than 10 μm and less than 18 μm, or greater than 12 μm and less than 18 μm. The length Hx of the unit prism 60 in the third direction D3 is equivalent to the height Hx of the unit prism 60.

[0216] The length of the optical sheet 50 in the third-direction D3 can be greater than 115 μm and less than 175 μm, greater than 125 μm and less than 175 μm, or greater than 135 μm and less than 175 μm. The length of the optical sheet 50 in the third-direction D3 can be greater than 115 μm and less than 165 μm, greater than 125 μm and less than 165 μm, or greater than 135 μm and less than 165 μm. The length of the optical sheet 50 in the third-direction D3 is equivalent to the thickness of the optical sheet 50.

[0217] The optical sheet 50 can be manufactured using extrusion molding, UV molding, injection molding, etc. Various materials can be used as the material for the optical sheet 50. The material of the optical sheet 50 may also include a transparent resin with one or more of the following as its main component: acrylic resin, polystyrene resin, polycarbonate resin, polyethylene terephthalate resin, polyacrylonitrile resin, etc. The material of the optical sheet 50 may also include epoxy acrylate resin, polyurethane acrylate resin-based reactive resins (such as ionizing radiation-curing resins).

[0218] like Figure 3 and Figure 4 As shown, the reflective sheet 70 is sheet-shaped. The reflective sheet 70 reflects light emitted from the back surface 32 of the light guide plate 30, causing it to return to the light guide plate 30. The reflection of the reflective sheet 70 can be specular reflection, diffuse reflection, or anisotropic diffuse reflection. A reflective sheet 70 with specular reflection function may also include a surface layer of a thin metal film. A reflective sheet 70 with diffuse reflection function may be a sheet containing inorganic particles such as titanium dioxide or silicon dioxide. A reflective sheet 70 with anisotropic diffuse reflection function may be a sheet containing light-diffusing components along its length in an oriented state, or a sheet containing protrusions or concave portions along its length in an oriented state.

[0219] The total light reflectivity of the reflector 70 can be above 75%, above 80%, or above 85%. By setting a lower limit for the total light reflectivity, the utilization efficiency of the light source can be improved. There is no specific upper limit for the total light reflectivity of the reflector 70. The total light reflectivity of the reflector 70 can be below 100%, or less than 100%. The total light reflectivity of the reflector 70 can be above 75% and below 100%, above 80% and below 100%, or above 85% and below 100%. The total light reflectivity of the reflector 70 can be above 75% and less than 100%, above 80% and less than 100%, or above 85% and less than 100%.

[0220] By using the reflective sheet 70 with diffuse reflection function, the viewing angle in the display device 10 using the surface light source device 20 can be effectively expanded. A lower limit can also be set for the diffuse reflectivity of the reflective sheet 70. By setting a lower limit for the diffuse reflectivity of the reflective sheet 70, the viewing angle can be effectively expanded. The diffuse reflectivity of the reflective sheet 70 can be 65% or more, 70% or more, or 75% or more.

[0221] An upper limit can also be set for the diffuse reflectance of the reflector 70. By setting an upper limit for the diffuse reflectance of the reflector 70, the reduction in the maximum brightness can be suppressed. The diffuse reflectance of the reflector 70 can be below 90%, below 87%, or below 85%. Diffuse reflectance (%) is the omnidirectional diffuse reflectance after removing the specular reflection portion from the total light reflectance.

[0222] The diffuse reflectivity of the reflective sheet 70 can be above 65% and below 90%, above 70% and below 90%, or above 75% and below 90%. The diffuse reflectivity of the reflective sheet 70 can be above 65% and below 87%, above 70% and below 87%, or above 75% and below 87%. The diffuse reflectivity of the reflective sheet 70 can be above 65% and below 85%, above 70% and below 85%, or above 75% and below 85%.

[0223] The total light reflectance (%) was determined using measurements of spectroscopic total light reflectance. In determining the total light reflectance, measurements of the spectroscopic total light reflectance for each wavelength per 1 nm were used in the visible light wavelength region above 380 nm and below 780 nm. A D65 light source was used for the measurement of spectroscopic total light reflectance. The angle of incidence relative to the sample surface was 8°. The measurement environment for the spectroscopic total light reflectance was: temperature 23℃±2℃, relative humidity 50%±5%. Before the test, the sample to be measured was placed in the measurement environment for 16 hours. Before measuring the spectroscopic total light reflectance, the light source of the measuring device was turned on for 15 minutes to allow the light source output to stabilize.

[0224] When measuring the total reflectance of the spectrophotometer, a black plate is attached to the back side of the sample, facing the incident surface, through an optically transparent adhesive sheet. The optically transparent adhesive sheet is "PANACLEAN PD-S1" manufactured by PANAC Corporation. The black plate is "Comoglass DFA2CG 502K (Black) series" manufactured by Kuraray Corporation.

[0225] In measuring total reflectance, the UH4150 UV-Vis-NIR spectrophotometer manufactured by Hitachi High Technology Co., Ltd. can also be used. A standard integrating sphere (with 4 apertures) with a diameter of 60 mm can also be used as the reflectance detector.

[0226] Regarding the determination of total light reflectance, the following formula (X) is used, which is equivalent to the visible light reflectance specified in formula (18) in column “7.2 Basic Formula” of JIS R 3106:2019. According to formula (X), total light reflectance is calculated taking into account the CIE daylight D65 spectral distribution of the light source and the CIE light-adaptation standard relative visibility. The total light reflectance is determined as a weighted average of the total spectral reflectance of the spectrophotometer, with the CIE daylight D65 spectral distribution of the light source and the CIE light-adaptation standard relative visibility used as weighting coefficients. In formula (X), “A(λ)” is the spectral distribution of the D65 light source. In formula (X), “B(λ)” is the CIE light-adaptation standard relative visibility. In formula (X), “C(λ)” is the total spectral reflectance of the spectrophotometer (%).

[0227] [Formula 1]

[0228] Total diffuse reflectance is defined as the difference between total reflectance and specular reflectance. Specular reflectance is determined using measurements of spectroscopic specular reflectance. In determining specular reflectance, measurements of spectroscopic specular reflectance for each wavelength in the visible light wavelength region above 380 nm and below 780 nm are used. A D65 light source is used in the measurement of spectroscopic specular reflectance. The angle of incidence relative to the sample surface is 8°. The measurement environment for spectroscopic specular reflectance is: temperature 23℃ ± 2℃, relative humidity 50% ± 5%. Before the test, the sample to be measured is placed in the measurement environment for 16 hours. Before measuring the spectroscopic specular reflectance, the light source of the measuring device is lit for 15 minutes to allow the light source output to stabilize. For spectroscopic specular reflectance, the measuring device used in the measurement of total spectroscopic reflectance can be used.

[0229] When measuring the reflectivity of the beam splitter, a black plate is attached to the back side of the sample being measured, facing the incident surface, through an optically transparent adhesive sheet. The optically transparent adhesive sheet is "PANACLEAN PD-S1" manufactured by PANAC Corporation. The black plate is "Comoglass DFA2CG 502K (Black) series" manufactured by Kuraray Corporation. When measuring the reflectivity of the beam splitter, the incident surface is the side of the reflector that faces the light guide plate.

[0230] In determining specular reflectance, the following formula (Y) is used, which is equivalent to the visible light reflectance specified in formula (18) in column “7.2 Basic Formula” of JIS R 3106:2019. According to formula (Y), the specular reflectance is calculated considering the CIE daylight D65 spectral distribution of the light source and the CIE light-adaptive standard relative visibility. The specular reflectance is determined as a weighted average of the spectroscopic specular reflectances, using the CIE daylight D65 spectral distribution of the light source and the CIE light-adaptive standard relative visibility as weighting coefficients. In formula (Y), “A(λ)” is the spectral distribution of the D65 light source. In formula (Y), “B(λ)” is the CIE light-adaptive standard relative visibility. In formula (Y), “D(λ)” is the spectroscopic specular reflectance (%).

[0231] [Equation 2]

[0232] An upper limit can also be set for the specular gloss G(20) of the reflector 70 at an incident angle of 20°. The specular gloss G(20) of the reflector 70 at an incident angle of 20° can be 200 or less, 150 or less, or 100 or less, expressed in two significant figures. By setting an upper limit for the specular gloss G(20) of the reflector 70 at an incident angle of 20°, the reflector 70 can be given a diffuse reflection function. In particular, light incident on the reflector 70 at a small incident angle can be diffused. Therefore, the viewing angle in the display device 10 using the surface light source device 20 can be effectively expanded.

[0233] A lower limit can also be set for the specular gloss G(20) of the reflector 70 at an incident angle of 20°. By setting a lower limit for the specular gloss G(20) of the reflector 70 at an incident angle of 20°, the reduction of the maximum brightness can be suppressed. The specular gloss G(20) of the reflector 70 at an incident angle of 20° can be 65 or higher, 75 or higher, or 85 or higher.

[0234] The specular gloss G(20) can be 65 or higher and below 200, 75 or higher and below 200, or 85 or higher and below 200. The specular gloss G(20) can be 65 or higher and below 150, 75 or higher and below 150, or 85 or higher and below 150. The specular gloss G(20) can be 65 or higher and below 100, 75 or higher and below 100, or 85 or higher and below 100.

[0235] A lower limit can also be set for the specular gloss G(85) of the reflector 70 at an incident angle of 85°. The specular gloss G(85) of the reflector 70 at an incident angle of 85° can be 75 or higher, 85 or higher, or 90 or higher. By setting a lower limit for the specular gloss G(85) of the reflector 70 at an incident angle of 85°, the diffusion of light incident on the reflector 70 at a large incident angle can be suppressed. As a result, the reduction of the maximum brightness can be suppressed.

[0236] An upper limit can also be set for the specular gloss G(85) of the reflector 70 at an incident angle of 85°. By setting an upper limit for the specular gloss G(85) of the reflector 70 at an incident angle of 85°, the viewing angle can be expanded. Regarding the specular gloss G(85) of the reflector 70 at an incident angle of 85°, it can be 110 or less, 105 or less, or 100 or less, expressed in two significant figures.

[0237] The specular gloss G(85) can be 75 or higher and 110 or lower, or 90 or higher and 110 or lower. The specular gloss G(85) can be 75 or higher and 105 or lower, or 90 or higher and 105 or lower. The specular gloss G(85) can be 75 or higher and 100 or lower, or 90 or higher and 100 or lower.

[0238] Alternatively, the aforementioned upper limit can be set for the specular gloss G(20) of the reflector 70 at an incident angle of 20°, and the aforementioned lower limit can be set for the specular gloss G(85) of the reflector 70 at an incident angle of 85°. Specifically, the specular gloss G of the reflector 70 at an incident angle of 20° can be 200 or less, and the specular gloss of the reflector 70 at an incident angle of 85° can be 75 or more. According to this example, the viewing angle can be effectively expanded while sufficiently suppressing the reduction of the maximum brightness value.

[0239] The ratio (G(85) / G(20)) of the specular gloss G(85) of the reflector 70 at an incident angle of 85° to the specular gloss G(20) of the reflector 70 at an incident angle of 20° can be 0.85 or higher, 0.90 or higher, or 0.95 or higher. By setting a lower limit for the ratio (G(85) / G(20)), it is possible to suppress the diffusion of light incident at a large incident angle while allowing the diffusion of light incident at a small incident angle. Thus, while suppressing the reduction of the maximum brightness, the viewing angle in the display device 10 using the surface light source device 20 can be effectively expanded. The upper limit of the ratio (G(85) / G(20)) is not specifically set. The ratio (G(85) / G(20)) can be 2.2 or lower, 1.6 or lower, or 1.2 or lower.

[0240] The ratio (G(85) / G(20)) can be greater than 0.85 and less than 2.2, greater than 0.90 and less than 2.2, or greater than 0.95 and less than 2.2. The ratio (G(85) / G(20)) can be greater than 0.85 and less than 1.6, greater than 0.90 and less than 1.6, or greater than 0.95 and less than 1.6. The ratio (G(85) / G(20)) can be greater than 0.85 and less than 1.2, greater than 0.90 and less than 1.2, or greater than 0.95 and less than 1.2.

[0241] The difference between the specular gloss G(20) and the specular gloss G(85) of the reflector 70 at an incident angle of 20° (G(20)-G(85)) can be less than 0, less than -2.0, less than -4.5, or less than -5.0, expressed in two significant figures. By setting an upper limit for the difference in specular gloss (G(20)-G(85)), it is possible to suppress the diffusion of light incident at a large incident angle while allowing the diffusion of light incident at a small incident angle. Thus, while suppressing the reduction of the maximum brightness, the viewing angle in the display device 10 using the surface light source device 20 can be effectively expanded. The lower limit of the difference in specular gloss (G(20)-G(85)) is not specifically set. The difference in specular gloss (G(20)-G(85)) can be greater than -75, greater than -45, or greater than -15.

[0242] The difference in specular gloss (G(20) - G(85)) can be above -75 and below 0, above -45 and below 0, or above -15 and below 0. The difference in specular gloss (G(20) - G(85)) can be above -75 and below -2.0, above -45 and below -2.0, or above -15 and below -2.0. The difference in specular gloss (G(20) - G(85)) can be above -75 and below -5.0, above -45 and below -5.0, or above -15 and below -5.0.

[0243] The angle θMAX at which the maximum brightness value BMAX in the brightness distribution on the light-emitting surface 31 of the light guide plate 30 is obtained will not deviate significantly from 60°. Therefore, the light emitted from the light-emitting surface 31 or the back surface 32 of the light guide plate 30 at an emission angle θk of approximately 60° can be efficiently utilized in the surface light source device 20. Therefore, the specular gloss G(60) of the reflector 70 at an incident angle of 60° can be closer to the specular gloss G(85) of the reflector 70 at an incident angle of 85° than the specular gloss G(20) of the reflector 70 at an incident angle of 20°.

[0244] Based on this, the specular gloss G(20) of the reflector 70 at an incident angle of 20°, the specular gloss G(60) of the reflector 70 at an incident angle of 60°, and the specular gloss G(85) of the reflector 70 at an incident angle of 85° can satisfy the following relationship.

[0245]

[0246] According to this example, it is possible to suppress the diffusion of light incident at a large angle of incidence while allowing light incident at a small angle of incidence to diffuse. Therefore, while suppressing the reduction of the maximum brightness, the viewing angle in the display device 10 using the surface light source device 20 can be effectively expanded.

[0247] Similarly, the specular gloss G(20) of the reflector 70 at an incident angle of 20°, the specular gloss G(60) of the reflector 70 at an incident angle of 60°, and the specular gloss G(85) of the reflector 70 at an incident angle of 85° can satisfy the following relationship.

[0248]

[0249] According to this example, it is possible to suppress the diffusion of light incident at a large angle of incidence while allowing light incident at a small angle of incidence to diffuse. Therefore, while suppressing the reduction of the maximum brightness, the viewing angle in the display device 10 using the surface light source device 20 can be effectively expanded.

[0250] "|G(60)-G(85)|" refers to the absolute value of the difference between the specular gloss G(60) of reflector 70 at an incident angle of 60° and the specular gloss G(85) of reflector 70 at an incident angle of 85°. "|G(20)-G(60)|" refers to the absolute value of the difference between the specular gloss G(20) of reflector 70 at an incident angle of 20° and the specular gloss G(60) of reflector 70 at an incident angle of 60°.

[0251] A lower limit can also be set for the specular gloss G(60) of the reflector 70 at an incident angle of 60°. The specular gloss G(60) of the reflector 70 at an incident angle of 60° can be 85 or higher, 95 or higher, or 105 or higher, expressed in two significant figures. By setting a lower limit for the specular gloss G(85) of the reflector 70 at an incident angle of 60°, the diffusion of light incident on the reflector 70 at a large incident angle can be suppressed. Therefore, the reduction of the maximum brightness can be suppressed.

[0252] An upper limit can also be set for the specular gloss G(60) of the reflector 70 at an incident angle of 60°. By setting an upper limit for the specular gloss G(60) of the reflector 70 at an incident angle of 60°, the viewing angle can be expanded. The specular gloss G(60) of the reflector 70 at an incident angle of 60° can be 140 or less, 130 or less, or 120 or less, expressed in two significant figures.

[0253] Regarding the specular gloss G(60), to two significant figures, it can be 85 or higher and 140 or lower, or 95 or higher and 140 or lower, or 105 or higher and 140 or lower. Regarding the specular gloss G(60), to two significant figures, it can be 85 or higher and 130 or lower, or 95 or higher and 130 or lower, or 105 or higher and 130 or lower. Regarding the specular gloss G(60), to two significant figures, it can be 85 or higher and 120 or lower, or 95 or higher and 120 or lower, or 105 or higher and 120 or lower.

[0254] The ratio (G(85) / G(60)) of the specular gloss G(85) of the reflector 70 at an incident angle of 85° to the specular gloss G(60) of the reflector 70 at an incident angle of 60° can be 0.55 or higher, 0.65 or higher, or 0.75 or higher. The ratio (G(85) / G(60)) can be 2.0 or lower, 1.5 or lower, or 1.0 or lower. By setting an upper and lower limit for the contrast ratio (G(85) / G(60)), it is possible to suppress the diffusion of light incident at a large incident angle while allowing the diffusion of light incident at a small incident angle. As a result, the viewing angle in the display device 10 using the surface light source device 20 can be effectively expanded while suppressing the reduction of the maximum brightness value.

[0255] The ratio (G(85) / G(60)) can be greater than 0.55 and less than 2.0, greater than 0.65 and less than 2.0, or greater than 0.75 and less than 2.0. The ratio (G(85) / G(60)) can be greater than 0.55 and less than 1.5, greater than 0.65 and less than 1.5, or greater than 0.75 and less than 1.5. The ratio (G(85) / G(60)) can be greater than 0.55 and less than 1.0, greater than 0.65 and less than 1.0, or greater than 0.75 and less than 1.0.

[0256] The difference between the specular gloss G(60) and the specular gloss G(85) of the reflector 70 at an incident angle of 60° (G(60)-G(85)) can be less than 22, less than 21, or less than 20, expressed in two significant figures. The difference in specular gloss (G(60)-G(85)) can be greater than 10, greater than 15, or greater than 18, expressed in two significant figures. By setting upper and lower limits for the difference in specular gloss (G(60)-G(85)), it is possible to suppress the diffusion of light incident at large incident angles while allowing the diffusion of light incident at small incident angles. Therefore, while suppressing the reduction of the maximum brightness, the viewing angle in the display device 10 using the surface light source device 20 can be effectively expanded.

[0257] Regarding the difference (G(60) - G(85)), with two significant figures, it can be 10 or more and 22 or less, or 15 or more and 22 or less, or 18 or more and 22 or less. Regarding the difference (G(60) - G(85)), with two significant figures, it can be 10 or more and 21 or less, or 15 or more and 21 or less, or 18 or more and 21 or less. Regarding the difference (G(60) - G(85)), with two significant figures, it can be 10 or more and 20 or less, or 15 or more and 20 or less, or 18 or more and 20 or less.

[0258] Regarding specular gloss, except for setting the incident angles to 20°, 60°, and 85°, the specular gloss was set to the value measured according to JIS Z 8741:1997. The measurement environment for specular gloss was: temperature 23℃±2℃, relative humidity 50%±5%. Before the measurement, the sample to be measured was placed in the measurement environment for 16 hours. Before measuring the specular gloss, the light source of the measuring device was turned on for 15 minutes to stabilize the output of the light source.

[0259] When measuring specular gloss, a black plate is attached to the back side of the sample being measured, facing the incident surface, through an optically transparent adhesive sheet. The optically transparent adhesive sheet is "PANACLEAN PD-S1" manufactured by PANAC Corporation. The black plate is "Comoglass DFA2CG 502K (Black) series" manufactured by Kuraray Corporation. When measuring the specular gloss of the reflective sheet, the incident surface is the side of the reflective sheet facing the light guide plate.

[0260] like Figure 9 As shown, the reflective sheet 70 may contain multiple layers. (As...) Figure 9As shown, the reflector 70 may also include a surface layer 75, an internal diffusion layer 74, and a metal layer 72 sequentially from the light guide plate 30. With such a structure, the reflector 70 can achieve the characteristics of the aforementioned reflector; specifically, it can achieve one or more of the following optical characteristics.

[0261] • The total light reflectivity of the reflector is above 75% and below 100%.

[0262] • The diffuse reflectivity of the reflective sheet is above 65% and below 90%.

[0263] • G(20)≤200 and 75≤G(85)

[0264] ·|G(60)-G(85)|<|G(20)-G(60)|

[0265] ·G(60)-G(85)| / ((G(60)+G(85)) / 2)<|G(20)-G(60)| / ((G(20)+G(60)) / 2)

[0266] ·75≤G(85)≤110

[0267] ·0.85≤G(85) / G(20)

[0268] ·G(20)-G(85)≤0

[0269] Here, G(20) is the specular gloss of the reflective sheet 70 at an incident angle of 20°. G(60) is the specular gloss of the reflective sheet 70 at an incident angle of 60°. G(85) is the specular gloss of the reflective sheet 70 at an incident angle of 85°. For example, by enhancing the internal diffusion in the internal diffusion layer 74, it is possible to effectively increase G(20) while suppressing the increase of G(60) and G(85). For example, by enhancing the surface diffusion in the surface layer 75, it is possible to effectively increase G(60) and G(85) while suppressing the increase of G(20).

[0270] Surface layer 75 functions as an anti-adhesion layer. Surface layer 75 inhibits the reflective sheet 70 from contacting the surface of the light guide plate 30 and inhibits the reflective sheet 70 from adhering to the light guide plate 30. Surface layer 75 may also be a layer with an uneven surface. Surface layer 75 may also have an uneven surface formed by embossing. Alternatively, surface layer 75 may contain particles and adhesive resin, and have an uneven surface caused by the particles.

[0271] The internal diffusion layer 74 diffuses the incident light. By providing the internal diffusion layer 74, the diffuse reflectivity of the reflector 70 can be increased. Through the combination of the surface layer 75 and the internal diffusion layer 74, the surface layer 75 reflects light at large incident angles. The internal diffusion layer 74 diffuses light at small incident angles that pass through the surface layer 75. By reducing the diffuse reflectivity at the surface layer 75, the diffuse reflectivity in the reflector 70 having the internal diffusion layer 74 and the surface layer 75 varies with the incident angle.

[0272] like Figure 9 As shown, the internal diffusion layer 74 may also include a base layer 74a and a light-diffusing component 74b retained in the base layer 74a. The internal diffusion layer 74 may also include one or more of the following as the light-diffusing component 74b: a metal compound, a porous material containing gas, resin beads with a metal compound surrounding them, white microparticles, and simple bubbles. The base layer 74a may also be a transparent resin. The material of the base layer 74a may also be a transparent resin with one or more of the following as its main component: acrylic resin, polystyrene resin, polycarbonate resin, polyethylene terephthalate resin, polyacrylonitrile resin, etc.

[0273] The metal layer 72 reflects light that has passed through the surface layer 75 and the inner diffusion layer 74. By providing the metal layer 72, the total light reflectivity of the reflective sheet 70 can be increased. The metal layer 72 can be a metal film with high reflectivity. The metal layer 72 can also be a vapor-deposited silver film.

[0274] like Figure 9 As shown, the reflector 70 may further include a support 71 and an anchoring layer 73. As in the example shown, the reflector 70 may also sequentially include a surface layer 75, an inner diffusion layer 74, an anchoring layer 73, a metal layer 72, and a support 71, starting from the light guide plate 30. The support 71 supports the other layers included in the reflector 70. The support 71 may also be a board made of resin, metal, paper, etc. The anchoring layer 73 may be a layer that improves the adhesion between the metal layer 72 and the inner diffusion layer 74.

[0275] Table 1 shows the reflection characteristics of the reflective sheets of samples 1-3. The reflective sheet 70 of sample 1 has... Figure 9The structures shown are as follows: The reflective sheet of Sample 1 includes a support 71, a metal layer 72 as a vapor-deposited silver layer, an anchoring layer 73, an internal diffusion layer 74, and a surface layer 75. The reflective sheet of Sample 2 includes a support 71, a metal layer 72 as a vapor-deposited silver layer, an anchoring layer 73, and an internal diffusion layer 74. In Samples 1 and 2, the internal diffusion layer 74 is a polyethylene terephthalate sheet containing silica particles. The reflective sheet of Sample 3 includes a support 71 and a metal layer 72 as a vapor-deposited silver layer. In the reflective sheets of Samples 1 to 3, the same layers 71, 72, 73, and 74 are used. For the reflective sheets of Samples 1 to 3, the total light reflectance, specular reflectance, diffuse reflectance, and specular gloss were measured. In the measurements of total reflectance, specular reflectance, and diffuse reflectance, a UV-Vis-NIR spectrophotometer manufactured by Hitachi High Technology Co., Ltd. was used. Regarding specular gloss, a gloss meter (Model 14563) manufactured by BYK Gardner was used to measure the specular gloss G(20) at an incident angle of 20°, the specular gloss G(60) at an incident angle of 60°, and the specular gloss G(85) at an incident angle of 85°.

[0276] According to the results in Table 1, for light with an incident angle of 20°, the reflection characteristics of sample 1 are similar to those of sample 2, which has diffuse reflection characteristics. On the other hand, for light with an incident angle of 85°, the reflection characteristics of sample 1 are similar to those of sample 3, which has specular reflection characteristics.

[0277] [Table 1]

[0278] Next, the functions of the display device 10, the surface light source device 20, and the optical component 28 shown in the figure will be explained.

[0279] like Figure 3 As shown, light is emitted from the light-emitting element 25. Light rays L31 and L32 pass through the light-incident surface 33 and are incident on the light guide plate 30. Figure 3 As shown, light rays L31 and L32 are reflected by the light-emitting surface 31 and the back surface 32 within the light guide plate 30. The reflection at the light-emitting surface 31 and the back surface 32 results in total internal reflection caused by the difference in refractive index between the material constituting the light guide plate 30 and air. Light rays L31 and L32 repeatedly undergo reflection at the light-emitting surface 31 and the back surface 32, traveling within the light guide plate 30 in the first direction (light guiding direction) D1.

[0280] In the illustrated example, the back surface 32 includes an inclined surface 37. The inclined surface 37 is inclined such that it approaches the light-emitting surface 31 from the incident light surface 33 toward the opposite surface 34. The inclined surface 37, together with the connecting surface 39 and the flat surface 38, forms the back surface 32. In the illustrated example, the connecting surface 39 extends along a third direction D3. Therefore, most of the light L31, L32 traveling in the light guide plate 30 toward the first side in the first direction D1 does not incident on the connecting surface 39 in the back surface 32, but rather on the inclined surface 37 or the flat surface 38. Figure 6 As shown, the incident angle θa2 of light L61 when it is incident on the inclined surface 37 is smaller than the incident angle θa1 of light L61 when it was previously incident on the light-emitting surface 31 by an amount smaller than the inclined surface angle θy of the inclined surface 37. Then, the incident angle θa3 of light L61 when it is incident on the light-emitting surface 31 again is smaller than the incident angle θa2 of light L61 when it was previously incident on the inclined surface 37 by an amount smaller than the inclined surface angle θy of the inclined surface 37. That is, by utilizing the inclined surface 37 for reflection, each time the light is reflected on the light-emitting surface 31 and the back surface 32, the incident angle of the light decreases by an amount smaller than the inclined surface angle θy of the inclined surface 37. Therefore, each time the light is reflected by the inclined surface 37, the incident angle of light L31, L32, and L61 traveling within the light guide plate 30 toward the light-emitting surface 31 decreases by an amount equal to twice the inclined surface angle θy.

[0281] As described above, the incident angle of light toward the light-emitting surface 31 and the back surface 32 gradually decreases due to reflection by the inclined surface 37, thus becoming less than the critical angle for total internal reflection. Light incident at an incident angle less than the critical angle for total internal reflection toward the light-emitting surface 31 or the back surface 32 can be emitted from the light guide plate 30. The light L31 and L32 emitted from the light-emitting surface 31 are directed toward the optical sheet 50 disposed on the light-emitting side of the light guide plate 30. On the other hand, the light L32 emitted from the back surface 32 is reflected by the reflective sheet 70 disposed on the back surface of the light guide plate 30, and enters the light guide plate 30 and travels within the light guide plate 30.

[0282] In the illustrated example, as the light guide direction approaches the opposite surface 34 from the incident surface 33, the proportion of the inclined surface 37 in the back surface 32 increases. With this structure, in the region of the light guide plate 30 near the incident surface 33 where there is a tendency for increased emitted light, excessive emitted light from the emitting surface 31 of the light guide plate 30 can be suppressed. In the region of the light guide plate 30 away from the incident surface 33 where there is a tendency for decreased emitted light, the emitted light from the emitting surface 31 of the light guide plate 30 can be sufficiently ensured. Thus, the emitted light along the first direction D1, which is the light guiding direction, can be homogenized.

[0283] Since the light previously traveled mainly within the light guide plate 30 in the first direction D1, the exit angle θk of the light emitted from the light guide plate 30 is as follows: Figure 6As shown, it becomes larger. The emission angle is the angle (°) between the direction of travel of the emitted light and the normal direction of the component such as the plate that causes the light to exit. The emission angle is an angle of 0° or more and 90° or less. The emission angle θk is biased within a narrow range of angles that become relatively large. The light emitted from the light guide plate 30 is directed within a narrow range of angles that are significantly tilted relative to the third direction D3.

[0284] Figure 10 An example of the angular distribution of brightness measured at the light-emitting surface 31 of the light guide plate 30 is shown. This angular distribution of brightness is the angular distribution of brightness measured for a surface light source device 20 with the structure on the side closer to the light-emitting surface 21 of the light guide plate 30 removed. Figure 10 The brightness distribution shown is the result of an actual survey of the brightness in each direction on the light-emitting surface 31, in the plane parallel to both the first direction D1 and the third direction D3. Figure 10 In the graph shown, the angle of the direction in which the measured brightness is recorded on the horizontal axis is taken as the positive value, which is the angle of inclination from the third direction D3 to the first side on the first direction D1.

[0285] For the surface light source device 20 employing the aforementioned shape and size range, an investigation was conducted. Figure 10 The brightness angle distribution is shown. The brightness angle distribution is the brightness distribution in each direction on the light-emitting surface 31 of the light guide plate 30, in a plane parallel to both the third direction D3 and the first direction D1 of the light guide plate 30. The angle θMAX in the brightness angle distribution can satisfy equation (1). By adjusting the shape or size of each component, the angle θMAX in the brightness angle distribution can also further satisfy equation (2). The angle θMAX is the angle at which the direction of obtaining the maximum brightness BMAX in the brightness angle distribution tilts from the third direction D3 of the light guide plate 30 to the first side on the first direction D1.

[0286] 60°≤θMAX≤85°···(1)

[0287] 70°≤θMAX≤80°···(2)

[0288] The half-peak and half-width HW in the brightness angle distribution can satisfy equation (3). It can also satisfy equation (4) by adjusting the shape or size of each component. Half-peak and half-width HW is the angle at which the direction of brightness BF, which is half of the brightness value, is tilted from the direction of the brightness value to the other side of the first direction D1 between the third direction D3 of the light guide plate 30 and the direction of obtaining the maximum brightness value BMAX.

[0289] 5°≤HW≤25°···(3)

[0290] 5°≤HW≤15°···(4)

[0291] Light emitted from the light guide plate 30 then enters the optical sheet 50. As described above, the optical sheet 50 includes a unit prism 60, wherein the top 63 of the unit prism 60 protrudes towards one side of the light guide plate 30. The longitudinal direction of the unit prism 60 intersects the light guiding direction D1 based on the light guide plate 30. Figure 3 In the example shown, the length direction of the unit prism 60 is orthogonal to the light guiding direction D1.

[0292] like Figure 3 and Figure 6 As shown, light rays L31, L32, and L61 directed towards the optical plate 50 pass through the second prism surface 62 of the unit prism 60 and are incident on the unit prism 60. For example... Figure 3 and Figure 6 As shown, light rays L31, L32, and L61 are reflected by the second prism surface 62 on the first prism surface 61, which faces the second prism surface 62 in the first direction D1, causing their travel directions to change. The reflection on the first prism surface 61 can also be total internal reflection.

[0293] exist Figure 3 and Figure 6 In the cross section shown, parallel to both the third direction D3 and the first direction D1, i.e., the main cross section of the optical sheet, light rays L31, L32, and L61 traveling in a narrow angle range inclined significantly from the third direction D3 are bent by total internal reflection at the first prism surface 61, such that the angle between their travel direction and the third direction D3 decreases. The optical sheet 50 causes the travel direction of light traveling in a direction inclined significantly towards the third direction D3 to rise along the third direction D3 by reflection at the unit prism 60. In combination with the light guide plate 30 that satisfies the above conditions (1) and (3), the optical sheet 50 can perform excellent optical path adjustment function. Furthermore, in combination with the light guide plate 30 that satisfies the above conditions (2) and (4), the optical sheet 50 can perform even better optical path adjustment function.

[0294] The light path, adjusted by the unit prism 60, is directed toward the first surface 51 of the optical sheet 50. The first surface 51 constitutes the emitting surface 21 of the surface light source device 20. Light passes through the emitting surface 21 and is emitted from the optical component 28 and the optical sheet 50. The light emitted from the emitting surface 21 illuminates the display panel 15 from the back. The display panel 15 forms an image on the display surface 11 by selectively allowing light from the surface light source device 20 to pass through each pixel. An observer can view the image on the display surface 11.

[0295] However, conventional optical components and optical sheets, which include a light guide plate with an inclined surface and an optical sheet with a prism surface facing the light guide plate, exhibit strong light-gathering capabilities. Therefore, conventional optical components and optical sheets can improve brightness in specific directions, such as the frontal direction. However, the amount of light in directions other than those specific directions is relatively low. In display devices using surface light sources, the viewing angle becomes narrower. In contrast, according to this embodiment, as described below, the viewing angle in display devices using surface light sources can be effectively expanded.

[0296] According to this embodiment, whenever reflected by the inclined surface 37, the incident angle of the light traveling within the light guide plate 30 toward the light emitting surface 31 decreases by twice the angle of inclination θy of the inclined surface 37. Lights L31 and L32 traveling within the light guide plate 30 can exit from the light emitting surface 31 when the incident angle toward the light emitting surface 31 is less than the critical angle for total internal reflection. By setting the inclined surface angle θy to a smaller value within the aforementioned range, the light emitted from the light guide plate 30 travels in a narrower angle range that is significantly inclined relative to the third direction D3. That is, the light guide plate can limit the emission direction of the light emitted from the light emitting surface 31 to a narrower angle range that is significantly inclined relative to the third direction D3. The light emitted from the light guide plate 30 is incident on the optical sheet 50 through the second prism surface 62. The light passing through the second prism surface 62 is reflected by the first prism surface 61. Through reflection on the first prism surface 61, the direction of light travel can be significantly changed. The light reflected from the first prism surface 61 can also travel in a narrower angular range after being reflected at the first prism surface 61.

[0297] As described above, the tilt angle difference (dθ = tilt angle θxe1 of the first element surface 66 - tilt angle θxe3 of the third element surface) between the first element surface 61 and the third element surface 68 can also be 5° or more. The tilt angle difference dθ between the first element surface 66 and the third element surface 68 can also be greater than twice the tilt angle of the tilted surface 37 relative to the first direction D1. The tilt angle difference dθ (°) between the first element surface 66 and the third element surface 68 can also be set to half-peak and half-width HW (°) or more in the angular distribution of brightness at the light-emitting surface 31. Such a tilt angle difference dθ of the first element surface 61 is generally larger than the deviation angle of the direction of travel of light incident into the optical sheet 50 through the second element surface 62. Therefore, by setting the tilt angle difference dθ of the first element surface 61 as described above, light traveling in a narrower angular range and incident on the first element surface 61 can be effectively diffused. This expands the viewing angle in the display device 10 using this surface light source device 20.

[0298] In particular, in this embodiment, light incident on the first prism surface 61 of the optical sheet 50 is directed towards a narrower angular range through the light path adjustment function in the light guide plate 30. The focused light is diffused to a desired degree using the first prism surface 61. Therefore, excessive light diffusion at the first prism surface 61 can be avoided. By suppressing the generation of stray light and light loss, the light source can be utilized efficiently. Thus, in the display device 10 using the surface light source device 20, the viewing angle can be effectively expanded while sufficiently suppressing the reduction of the maximum brightness value.

[0299] Furthermore, in Patent Document 1 (Japanese Patent Application Publication No. 2016-95347), which is described as prior art, a scheme of giving a folded surface to a unit prism is also proposed. In this prior art, the tilt angle of the element facets included in the unit prism relative to the third direction D3 also decreases from the end of the unit prism toward the base end. In Patent Document 1, it is proposed to arrange an element facet with a larger angle relative to the third direction D3 on the end side where light is more easily incident due to its relatively tilt, and to arrange an element facet with a smaller angle relative to the third direction D3 on the base side where light is more easily incident due to its relatively upright position, thereby ensuring excellent light-gathering function. In this prior art, the difference in tilt angles of the element facets included in the first prism surface is not studied, and no lower limit for the difference in tilt angles is set; therefore, the prism surface performs a light-gathering function opposite to the diffusion function. Based on this, it can be said that the effect of giving the first prism 61 a diffusion function by setting a lower limit on the difference in tilt angle dθ between the first element surface 66 and the third element surface 68 of the first prism 61 becomes significant, exceeding the range that can be predicted according to the current level of technology.

[0300] Furthermore, as described above, the emitted light from the light-emitting surface of the light guide plate travels within a narrow angle range that is significantly tilted relative to the frontal direction. In combinations with such light guide plates, conventionally, the reflection at the reflector is specular reflection. Specular reflection suppresses the situation where the direction of light travels within the light guide plate before exiting from the rear is significantly different from the direction of light that is reflected by the reflector and re-incidentally enters the light guide plate. Therefore, even for re-incident light, the light path adjustment function of the light guide plate and the reflector effectively functions. That is, by setting the reflection of the reflector to positive reflection, the direction of light travel from the light-emitting surface of the light guide plate can be kept within a narrower angle range that is significantly tilted relative to the frontal direction.

[0301] In contrast, in this embodiment, the diffuse reflectivity of the reflective sheet 70 can also be set to 65% or more. That is, the reflection at the reflective sheet can be mainly diffuse reflection.

[0302] As described above, the light guide plate 30 having the connecting surface 39 and the inclined surface 37 can be manufactured by extrusion molding, UV molding, injection molding, etc. However, it is also conceivable that it is impossible to give the end of the inclined surface 37 or the portion of the back surface 32 adjacent to the connecting surface 39, such as the end of the inclined surface 37 or the end of the flat surface 38, a shape with sufficient high precision. The light emitted from the back surface 32 also includes light that diffuses in the ineffective area of ​​the back surface 32 where it cannot be processed with sufficient high precision. In addition, there is also light that is reflected by the reflector and then incident on the connecting surface and diffuses. That is, the light emitted from the back surface includes light emitted from the light guide plate as diffused light.

[0303] By making the reflection at the reflector 70 diffuse, the reflector 70 can moderately diffuse only the light emitted from the back surface 32. Light emitted from the light-emitting surface 31, rather than from the back surface 32, is precisely affected by the light path adjustment function of the light guide plate 30 and is not diffused by the reflector 70. Therefore, it is possible to maintain strong directivity in the emission direction from the light-emitting surface 31 of the light guide plate 30 while uniformly diffusing other light. Thus, in the display device 10 using the surface light source device 20, it is possible to effectively expand the viewing angle while sufficiently suppressing the decrease in the maximum brightness.

[0304] The diffuse reflectivity of the reflective sheet 70 can be below 90%. By setting an upper limit on the diffuse reflectivity, the specular reflection component can be ensured. This, in turn, suppresses the reduction in the maximum brightness.

[0305] Alternatively, the specular gloss G(85) of the reflective sheet 70 at an 85° incident angle can be set to 75 or higher, and the specular gloss G(20) of the reflective sheet 70 at an 80° incident angle can be set to 200 or lower. The specular gloss G(85) of the reflective sheet 70 at an 85° incident angle can be 75 or higher and 110 or lower. The ratio of the specular gloss G(85) of the reflective sheet 70 at an 85° incident angle to the specular gloss G(20) of the reflective sheet 70 at an 80° incident angle (G(85) / G(20)) can be 0.85 or higher. The difference between the specular gloss G(20) of the reflective sheet 70 at an 85° incident angle and the specular gloss G(85) of the reflective sheet 70 at an 85° incident angle (G(20)-G(85)) can be 0 or lower. That is, the reflection of light incident on the reflector 70 at an incident angle of 85° can also include a large amount of orthographic reflection (i.e., specular reflection). By using one or more of these structures, it is possible to increase the specular reflectivity of light incident on the reflector 70 at larger incident angles including 85°, while also increasing the diffuse reflectivity of light incident on the reflector 70 at smaller incident angles including 20°.

[0306] Regarding the light emitted from the back surface 32 after the light guide plate 30 has been appropriately subjected to a light path adjustment function, that is, the light traveling from the back surface 32 of the light guide plate 30 in a direction that is significantly inclined relative to the third direction D3, its angle of incidence becomes larger. Such light, incident at a large angle of incidence on the reflector 70, is easily orthogonally reflected by the reflector 70, whose specular gloss has been adjusted as described above. Therefore, the light emitted from the back surface 32 after the light guide plate 30 has been appropriately subjected to a light path adjustment function is selectively orthogonally reflected by the reflector 70, and can return to the light guide plate 30 while maintaining its direction of travel. This light can then be emitted from the light emitting surface 31 of the light guide plate 30 in a direction that is significantly inclined relative to the third direction D3. The light emitted from the light emitting surface 31 of the light guide plate 30 in a direction that is significantly inclined relative to the third direction D3 can travel in the direction that yields the maximum brightness. Therefore, the reflector 70, whose specular gloss has been adjusted as described above, can maintain a direction of travel that easily contributes to the maximum brightness of the light.

[0307] Among the light emitted from the back surface 32 of the light guide plate 30, there is also light that has not been subjected to the optical path adjustment function provided by the inclined surface 37 of the light guide plate 30. This light does not exit in the direction of maximizing brightness. The exit angle of such light emitted from the light guide plate 30 is smaller than the exit angle of light that has not been subjected to the optical path adjustment function provided by the inclined surface 37 of the light guide plate 30. The reflector 70 diffusely reflects light incident at a small angle of incidence with a high diffuse reflectivity. Therefore, the reflector 70 can selectively diffusely reflect light that is unlikely to contribute to maximizing brightness.

[0308] Based on the above, a strong directivity can be maintained in the emission direction from the light-emitting surface 31 of the light guide plate 30, while other light can be diffused uniformly. Therefore, in the display device 10 using the surface light source device 20, the viewing angle can be effectively expanded while sufficiently suppressing the decrease in the maximum brightness.

[0309] In addition, such as Figure 9As shown, the reflector 70 may also sequentially include a surface layer 75, an internal diffusion layer 74, and a metal layer 72 starting from the light guide plate 30. With such a reflector 70, light L91 traveling in a direction significantly inclined relative to the third direction D3 can be reflected with high reflectivity by the surface layer 75. That is, light L91 with a large angle of incidence can be reflected primarily by the surface layer 75. Light L92 and L93 traveling in a direction not significantly inclined relative to the third direction D3 can be reflected by the internal diffusion layer 74 and the metal layer 72. That is, light L92 and L93 with a small angle of incidence can be reflected primarily by the internal diffusion layer 74 or the metal layer 72. With this reflector 70, the diffuse reflectivity can be adjusted according to the angle of incidence relative to the reflector 70. For example, by reducing the surface roughness Ra and Rz of the surface layer 75 and enhancing the internal diffusion of the internal diffusion layer 74, light L91 traveling in a direction significantly inclined relative to the third direction D3 can be primarily orthographically reflected on the surface of the surface layer 75. Lights L92 and L93 traveling in a direction that is not significantly tilted relative to the third direction D3 are diffusely reflected primarily within the internal diffusion layer 74. According to this example, the reflector 70 maintains the direction of travel of light L91, which easily contributes to the maximum brightness, and selectively diffuses light L92 and L93, which are less likely to contribute to the maximum brightness. That is, it is possible to maintain strong directivity in the emission direction from the light-emitting surface 31 of the light guide plate 30 while uniformly diffusing other light. Therefore, in the display device 10 using the surface light source device 20, the viewing angle can be effectively expanded while sufficiently suppressing the reduction of the maximum brightness.

[0310] Figure 11 The angular distribution of brightness on the first surface 51 of the optical sheet 50 is shown. The angular distribution of brightness on the first surface 51 of the optical sheet 50 is the brightness (cd / m²) in each direction within the surface, including the third direction D3 (which is the stacking direction of the light guide plate 30 and the optical sheet 50) and the first direction D1. 2 The distribution related to this. For example... Figure 11 As shown, the relationship between brightness and the following angle is illustrated: this angle (°) is the angle between the direction from which the brightness is obtained and the third direction D3. When the direction from which the brightness is obtained is tilted relative to the third direction D3 towards a first side in the first direction D1, the angle (°) between this direction and the third direction D3 is a positive value. That is, the angle on the horizontal axis is the positive value of the brightness emitted from the first surface 51 towards the direction tilted from the third direction D3 towards the first side in the first direction D1. The brightness angle distribution on the first surface 51 is a measurement value taken without removing components that are closer to the emitting surface 21 than the surface light source device 20.

[0311] exist Figure 11In the graphs shown, the solid line represents the angular distribution of the surface light source device including the reflector 70 of sample 1. The reflector 70 of sample 1 has the characteristics shown in Table 1. The dashed line represents the angular distribution of the surface light source device using the reflector of sample 3. The reflector of sample 3 has the characteristics shown in Table 1. Regarding the luminance ratio shown on the vertical axis of the graphs, in each example of the surface light source device, the luminance emitted from the optical sheet 50 at an exit angle of 0° is normalized to 100%.

[0312] Between the surface light source device whose brightness angle distribution is measured using solid lines and the surface light source device whose brightness angle distribution is measured using dashed lines, the structures other than the reflectors are identical. Regarding the light guide plates assembled in the surface light source device, the arrangement spacing PC is 0.115 mm, and the tilt angle θy is 0.5°. The dimensions of the optical plates assembled in the surface light source device are as follows.

[0313] • Inclination angle θxe1 of the first element surface: 40°

[0314] • The tilt angle θxe2 of the second element surface is 34°

[0315] • The tilt angle θxe3 of the third element surface: 27°

[0316] • Inclination angle θx2: 35°

[0317] • First element surface length Wxe1: 2.0 μm

[0318] • Second element surface length Wxe2: 2.5μm

[0319] • Length of the third element surface Wxe3: 3.9μm

[0320] Figure 11 The luminance of the angular distribution shown was measured using an EZ Contrast XL80 from ELDIM. Figure 11 The brightness of the brightness angle distribution shown is the measured value at the center position of the first surface 51 of the optical sheet 50 in the two directions of first direction D1 and second direction D2.

[0321] As in Figure 11 As shown by the solid line, in the measurement results of the surface light source device using the reflector 70 of Sample 1, a brightness peak was generated in the third direction D3, which is the frontal direction. (As shown in...) Figure 11As shown by the dashed line, in the measurement results of the surface light source device using the reflector sheet of sample 3, a brightness peak was generated in the third direction D3, which is the frontal direction. The brightness of the surface light source device using sample 1, shown by the solid line, is higher than that of the surface light source device using sample 3, which is shown by the dashed line, in a direction tilted at more than 20° relative to the third direction D3. That is, by using the reflector sheet 70, which includes a surface layer 75, an internal diffusion layer 74, and a metal layer 72 sequentially from the light guide plate 30, the viewing angle can be expanded while maintaining the directionality of the brightness. By using the reflector sheet 70, which includes a surface layer 75, an internal diffusion layer 74, and a metal layer 72 sequentially from the light guide plate 30, the utilization efficiency of the light source can be improved, and the frontal brightness can be maintained while effectively expanding the viewing angle.

[0322] Furthermore, the specular gloss G(60) of the reflector 70 at an incident angle of 60° and the specular gloss G(85) of the reflector 70 at an incident angle of 85° can also satisfy one of the following relationships.

[0323] ·0.55≤G(85) / G(60)≤2.0

[0324] ·15≤G(60)-G(85)≤22

[0325] Light emitted from the light-emitting surface 31 or the back surface 32 of the light guide plate 30 at an emission angle θk of 60° can also be efficiently utilized in the surface light source device 20. Therefore, by using a reflector 70 that satisfies these relationships, the maximum brightness can be effectively increased. Alternatively, the brightness in a direction that is not significantly tilted relative to the direction in which the maximum brightness is obtained can be increased.

[0326] Furthermore, the specular gloss G(20) of the reflector 70 at an incident angle of 20°, the specular gloss G(60) of the reflector 70 at an incident angle of 60°, and the specular gloss G(85) of the reflector 70 at an incident angle of 85° can also satisfy any of the following relationships.

[0327] ·|G(60)-G(85)|<|G(20)-G(60)|

[0328] ·|G(60)-G(85)| / ((G(60)+G(85)) / 2)<|G(20)-G(60)| / ((G(20)+G(60)) / 2)

[0329] By using a reflective sheet 70 that satisfies these relationships, light emitted in the direction of maximum brightness and at a small tilt angle relative to that direction can be specularly reflected with high reflectivity. Therefore, it is possible to suppress the diffusion of light incident at a large angle of incidence while simultaneously allowing the diffusion of light incident at a small angle of incidence. Consequently, while suppressing the reduction in maximum brightness, the viewing angle in the display device 10 using the surface light source device 20 can be effectively expanded.

[0330] As described above, the arrangement spacing PC of the connecting surfaces 39 in the first direction D1 can also be larger than the arrangement spacing PP1 of the pixels 16 in the first direction D1 of the display panel 15. The arrangement spacing PC of the connecting surfaces 39 in the first direction D1 can also be 0.060 mm or more. By extending the arrangement spacing PC of the connecting surfaces 39 in this way, the number of connecting surfaces 39 or the number of inclined surfaces 37 can be reduced. As described above, the light guide plate 30 having connecting surfaces 39 and inclined surfaces 37 can be manufactured by extrusion molding, UV molding, injection molding, etc. However, it is also conceivable that it is impossible to give the end of the inclined surface 37 or the portion of the back surface 32 adjacent to the connecting surface 39 with sufficient high precision, such as the end of the inclined surface 37 or the end of the flat surface 38. Light incident on the ineffective area of ​​the back surface 32 that cannot be processed with sufficient high precision will not travel in the expected direction. This light may become stray light. Even if this light is emitted from the light emitting surface 31, it may become light that cannot form an image in the display panel 15. That is, light incident on the ineffective area of ​​the back surface 32 may become ineffective light. In contrast, if the arrangement spacing PC of the connecting surfaces 39 is increased, the number of connecting surfaces 39 or the number of inclined surfaces 37 is reduced, thereby reducing the proportion of ineffective areas in the back surface 32. Therefore, the light path adjustment function in the light guide plate 30 functions more effectively. As a result, the utilization efficiency of the light source is improved, enabling both the widening of the viewing angle and the increase in brightness. For example, in the display device 10 using the surface light source device 20, the viewing angle can be effectively widened while sufficiently suppressing the reduction of the maximum brightness.

[0331] Furthermore, if the spacing between the connecting surfaces in the first direction is longer than the spacing between the pixels along the first direction of the display panel, moiré patterns are easily generated. Therefore, in conventional surface light source devices, the spacing between the connecting surfaces in the first direction is shorter than the spacing between the pixels along the first direction of the display panel.

[0332] This was investigated, and it was found that the arrangement spacing PC of the connecting surface 39 in the first direction D1 is such that even if it is longer than the arrangement spacing PP1 of the pixels 16 along the first direction D1 of the display panel 15, moiré patterns can be minimized. Furthermore, by adjusting the processing conditions within a previously selected range, the deviation of the arrangement spacing PC of the connecting surface 39 in the first direction D1 can be reduced. Thus, it was confirmed that even if the arrangement spacing PC of the connecting surface in the first direction is longer than previously possible, the problem of moiré pattern formation can be addressed.

[0333] Furthermore, if the spacing between the connecting surfaces in the first direction is increased, uneven brightness may occur due to the arrangement of the connecting surfaces or the inclined surfaces. Therefore, in conventional surface light source devices, the spacing between the connecting surfaces in the first direction is set to be shorter than the spacing between the pixels along the first direction of the display panel.

[0334] This was studied, and it was found that by setting the arrangement spacing PC of the connecting surface 39 in the first direction D1 to 0.37 mm or less, or by setting the ratio of the arrangement spacing PC of the connecting surface 39 in the first direction D1 to the arrangement spacing PP1 of the pixels 16 of the display panel 15 in the first direction D1 to 2.2 or less, the unevenness in brightness caused by the configuration of the connecting surface 39 or the inclined surface 37 can be made less noticeable.

[0335] Furthermore, by imparting diffuse reflection functionality to the reflective sheet 70, the brightness unevenness caused by the arrangement of the connecting surface 39 or the inclined surface 37 can be effectively reduced to a less noticeable state. It can be assumed that the brightness unevenness caused by the arrangement of the connecting surface 39 or the inclined surface 37 is also formed by light emitted from the back surface 32 of the light guide plate 30. By utilizing the reflective sheet 70 to directly diffuse the light causing the brightness unevenness, excessive diffusion can be avoided, thereby effectively reducing the noticeability of the brightness unevenness.

[0336] As described above, in this embodiment, the optical component 28 includes: a light guide plate 30, which includes a light-emitting surface 31 and a back surface 32 facing the light-emitting surface 31; and an optical sheet 50, which includes a prism surface 53 facing the light-emitting surface 31. The back surface 32 includes a plurality of inclined surfaces 37 and connecting surfaces 39 alternately arranged in a first direction D1. The inclined surfaces 37 are inclined relative to the first direction D1 such that they approach the light-emitting surface 31 on a first side in the first direction D1. The optical sheet 50 includes a plurality of unit prisms 60 arranged along the first direction D1. Each unit prism 60 includes a first prism surface 61 located on a first side in the first direction D1, and a second prism surface 62 facing the first prism surface 61 from the first direction D1. The prism surface 53 includes the first prism surface 61 and the second prism surface 62. The first prism surface 61 includes a first element surface 66, a second element surface 67, and a third element surface 68. The second element surface 67 is located between the first element surface 66 and the third element surface 68. The tilt angle difference dθ between the first element surface 66 and the third element surface 68 of the first prism surface 61 can also be 5° or more. The tilt angle difference dθ between the first element surface 66 and the third element surface 68 can also be greater than twice the tilt angle of the tilted surface 37 relative to the first direction D1. The tilt angle difference dθ (°) between the first element surface 66 and the third element surface 68 can also be half-peak and half-width HW (°) or more in the angular distribution of brightness at the light-emitting surface 31. According to this embodiment, the tilt angle difference dθ of the first prism surface 61 can be made larger than the deviation angle of the direction of travel of light incident into the optical sheet 50 through the second prism surface 62. Therefore, the viewing angle in the display device 10 using the surface light source device 20 can be effectively expanded.

[0337] In this embodiment, the optical component 28 includes: a light guide plate 30, which includes a light-emitting surface 31 and a back surface 32 facing the light-emitting surface 31; and a reflective sheet 70, which faces the back surface 32. The back surface 32 includes a plurality of inclined surfaces 37 and connecting surfaces 39 alternately arranged in a first direction D1. The inclined surfaces 37 are inclined relative to the first direction D1 such that they approach the light-emitting surface 31 on a first side in the first direction D1. The diffuse reflectivity of the reflective sheet 70 can be 50% or more. The light emitted from the back surface 32 includes light emitted from the light guide plate 30 as diffuse light. By making the 9-reflection at the reflective sheet 70 diffuse, the light emitted from the back surface 32 is moderately diffused by utilizing the reflective sheet 70, thereby maintaining a strong directivity in the emission direction emitted from the light-emitting surface 31 of the light guide plate 30 while uniformly diffusing other light. Thus, in the display device 10 using the surface light source device 20, the viewing angle can be effectively expanded while sufficiently suppressing the reduction of the maximum brightness value.

[0338] In this embodiment, the optical component 28 includes: a light guide plate 30, which includes a light-emitting surface 31 and a back surface 32 facing the light-emitting surface 31; and a reflective sheet 70, which faces the back surface 32. The back surface 32 includes a plurality of inclined surfaces 37 and connecting surfaces 39 alternately arranged in a first direction D1. The inclined surfaces 37 are inclined relative to the first direction D1 such that they approach the light-emitting surface 31 on a first side in the first direction D1. The reflective sheet 70 may also be configured to satisfy any one or more of the following. In addition, G (20) is the specular gloss G of the reflective sheet 70 at an incident angle of 20°. G (60) is the specular gloss G of the reflective sheet 70 at an incident angle of 60°. G (85) is the specular gloss G of the reflective sheet 70 at an incident angle of 85°.

[0339] The reflector 70 includes, in sequence from the light guide plate 30, a surface layer 75, an inner diffusion layer 74, and a metal layer 72. The inner diffusion layer 74 includes a base layer 74a and a light diffusion component 74b held within the base layer 74a.

[0340] • G(20)≤200 and 75≤G(85)

[0341] ·|G(60)-G(85)|<|G(20)-G(60)|

[0342] ·G(60)-G(85)| / ((G(60)+G(85)) / 2)<|G(20)-G(60)| / ((G(20)+G(60)) / 2)

[0343] • The diffuse reflectance of reflective sheet 70 is above 65% and below 90%.

[0344] ·75≤G(85)≤110

[0345] ·0.85≤G(85) / G(20)

[0346] ·G(20)-G(85)≤0

[0347] By using a reflector 70 that satisfies any condition, it is possible to maintain the direction of light that easily contributes to the maximum brightness, and selectively diffuse light that is difficult to contribute to the maximum brightness. That is, it is possible to maintain strong directivity in the emission direction emitted from the light-emitting surface 31 of the light guide plate 30 while uniformly diffusing other light. As a result, in the display device 10 using the surface light source device 20, it is possible to effectively expand the viewing angle while sufficiently suppressing the reduction of the maximum brightness.

[0348] In this embodiment, the optical component 28 includes: a light guide plate 30, which includes a light-emitting surface 31 and a back surface 32 facing the light-emitting surface 31; and an optical sheet 50, which includes a prism surface 53 facing the light-emitting surface 31. The back surface 32 includes a plurality of inclined surfaces 37 alternately arranged in a first direction D1, and a plurality of connecting surfaces 39 not parallel to the inclined surfaces 37. The inclined surfaces 37 are inclined relative to the first direction D1 such that their first side approaches the light-emitting surface 31 in the first direction D1. The arrangement spacing PC of the connecting surfaces 39 in the first direction D1 can also be larger than the arrangement spacing PP1 of the pixels 16 in the first direction D1 of the display panel 15. The arrangement spacing PC of the connecting surfaces 39 in the first direction D1 can also be 0.060 mm or more. By increasing the arrangement spacing PC of the connecting surfaces 39, the number of connecting surfaces 39 and the number of inclined surfaces 37 are reduced, and the proportion of ineffective areas that are not processed with sufficient high precision in the back surface 32 can be reduced. Therefore, the light path adjustment function in the light guide plate 30 can function more effectively. As a result, the utilization efficiency of the light source is improved, enabling both an expanded viewing angle and increased brightness. For example, in the display device 10 using the surface light source device 20, the viewing angle can be effectively expanded while sufficiently suppressing the decrease in the maximum brightness value.

[0349] This embodiment has been described with reference to specific examples, but the specific examples described above are not limiting to this embodiment. This embodiment described above can be implemented by various other specific examples, and various omissions, substitutions, changes, additions, etc., can be made without departing from its spirit.

[0350] Hereinafter, an example of a modification will be described with reference to the accompanying drawings. In the following description and the accompanying drawings used in the description, parts that can be constructed in the same way as the specific examples described above will be referred to by the same reference numerals as the corresponding parts in the specific examples described above, and repeated descriptions will be omitted.

[0351] Furthermore, various modifications can be made to the light guide plate 30, optical sheet 50, and reflective sheet 70 described above. For example, the second prism surface 62 of the optical sheet 50 can also be a folded surface containing multiple element faces. The second prism surface 62 can also be linearly symmetrical with respect to the first prism surface 61 in cross-sections along both the third direction D3 and the first direction D1, with an axis parallel to the third direction D3 as the center. In addition, the reflective sheet 70 may not include the internal diffusion layer 74, but instead include a surface layer 75 and a metal layer 72.

[0352] like Figure 12 As shown, a reflective layer 46 can also be superimposed on the opposite side 34 of the light guide plate 30. The reflective layer 46 can reflect light emitted from the opposite side 34 of the light guide plate 30. This improves the utilization efficiency of the light source.

[0353] Figure 13The angular distribution of brightness on the first surface 51 of the optical plate 50 is shown. Figure 13 The angular distribution of brightness shown by the solid line represents the angular distribution of a surface light source device using a light guide plate 30 containing a reflective layer 46. Figure 13 The angular distribution of brightness shown by the dashed line represents the angular distribution of a surface light source device using a light guide plate 30 that does not include the reflective layer 46. For Figure 13 The brightness angle distribution shown is consistent with Figure 11 The brightness angle distribution shown was measured in the same manner.

[0354] by Figure 13 The brightness angle distribution shown is used as the measurement object for the surface light source device. Figure 12 The structure shown. Figure 13 The brightness angle distribution shown is used as the measurement object for the surface light source device relative to the... Figure 11 The difference between the surface light source devices, which are measured using the dotted lines representing the brightness angle distribution, and the devices in question are: a reflective layer is provided on the opposite side of the light guide plate. Figure 13 The brightness angle distribution shown is used as the measurement object for the surface light source device and... Figure 11 The brightness angle distribution shown by the dashed line in the figure is the same structure for the surface light source device as the object of measurement, except for the reflective layer.

[0355] Figure 13 The luminance of the angular distribution shown was measured using an EZ Contrast XL80 from ELDIM. Figure 13 The brightness of the brightness angle distribution shown is the measured value at the center position of the first surface 51 of the optical sheet 50 in the two directions of first direction D1 and second direction D2.

[0356] like Figure 13 As shown, the brightness of the surface light source device with the reflective layer 46 included in the light guide plate 30 is higher in the direction inclined to the second side (light source side) in the first direction D1 relative to the third direction D3, compared to the brightness of the surface light source device without the reflective layer 46. By providing the reflective layer 46 on the light guide plate 30, the field of view in the direction inclined to the second side in the first direction D1 relative to the third direction can be expanded. That is, by overlapping the reflective layer 46 on the opposite surface 34 of the light guide plate 30, the utilization efficiency of the light source can be improved, thereby expanding the field of view.

[0357] Furthermore, the overall structure of the aforementioned surface light source device 20 and display device 10 can be modified in various ways. For example, the surface light source device 20 may also include a reflective polarizer.

[0358] Label Explanation

[0359] 10: Display device; 11: Display surface; 15: Display panel; 16: Pixel; 16A: First pixel; 16B: Second pixel; 16C: Third pixel; 20: Surface light source device; 21: Light-emitting surface; 24: Light source; 25: Light-emitting body; 28: Optical component; 30: Light guide plate; 31: Light-emitting surface; 32: Back side; 33: Light-incident surface; 34: Opposite surface; 35a: First side surface; 35b: Second side surface; 37: Inclined surface; 38: Flat surface; 39: Connecting surface; 46: Reflective layer; 50: Optical sheet; 51: First surface; 52: Second surface; 53: Prism surface; 55: Main body; 55a: 55b: Light-emitting side; 60: Unit prism; 61: First prism surface; 62: Second prism surface; 63: Top; 66: First element surface; 67: Second element surface; 68: Third element surface; 70: Reflector; 71: Support; 72: Metal layer; 73: Anchoring layer; 74: Internal diffusion layer; 74a: Base layer; 74b: Light diffusion component; 75: Surface layer; D1: First direction; D2: Second direction; D3: Third direction; θxe1: Inclination angle of the first element surface; θxe2: Inclination angle of the second element surface; θxe3: Inclination angle of the third element surface; θy: Inclined surface angle.

Claims

1. An optical component of a surface light source device, comprising: A light guide plate comprising a light-emitting surface and a back surface facing the light-emitting surface; and An optical element comprising a prism surface facing the light-emitting surface. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The optical sheet comprises a plurality of unit prisms arranged in the first direction. Each unit prism includes: a first prism surface located on a first side in the first direction; and a second prism surface facing the first prism surface from the first direction. The prism surface includes a first prism surface and a second prism surface. The first prism surface includes a first feature surface, a second feature surface, and a third feature surface. The second feature surface is located between the first feature surface and the third feature surface. The difference in tilt angle between the first feature surface and the third feature surface is greater than 5°. The difference in tilt angle between the first feature surface and the third feature surface is greater than twice the angle of the tilt surface relative to the first direction.

2. An optical component of a surface light source device, comprising: A light guide plate comprising a light-emitting surface and a back surface facing the light-emitting surface; and An optical element comprising a prism surface facing the light-emitting surface. The back surface includes a plurality of inclined surfaces alternately arranged in a first direction and a plurality of connecting surfaces that are not parallel to the inclined surfaces. The inclined surface is inclined relative to the first direction in such a way that it approaches the light-emitting surface on a first side in the first direction. The optical sheet comprises a plurality of unit prisms arranged in the first direction. Each unit prism includes: a first prism surface located on a first side in the first direction; and a second prism surface facing the first prism surface from the first direction. The prism surface includes a first prism surface and a second prism surface. The first prism surface includes a first feature surface, a second feature surface, and a third feature surface. The second feature surface is located between the first feature surface and the third feature surface. The difference in tilt angle between the first feature surface and the third feature surface is greater than twice the angle of the tilt surface relative to the first direction.

3. The optical component of the surface light source device according to claim 1 or 2, wherein, The spacing between the connecting surfaces in the first direction is 0.060 mm or more.

4. The optical component according to claim 1 or 2, wherein, The spacing between the connecting surfaces in the first direction is larger than the spacing between the pixels of the display panel disposed facing the ground with the surface light source device along the first direction.

5. The optical component according to claim 1 or 2, wherein, The ratio of the spacing of the connecting surface in the first direction to the spacing of the pixels of the display panel disposed facing the ground with the surface light source device in the first direction is 1.0 or more and 2.2 or less.

6. The optical component according to claim 1 or 2, wherein, The optical component has a reflective sheet facing the back side.

7. The optical component according to claim 6, wherein, The reflective sheet, starting from the light guide plate, sequentially comprises a surface layer, an internal diffusion layer, and a metal layer. The internal diffusion layer comprises a base layer and a light-diffusing component retained in the base layer.

8. The optical component according to claim 6, wherein, The reflective sheet has a specular gloss level of less than 200 at an incident angle of 20°. The reflective sheet has a specular gloss of 75 or higher at an incident angle of 85°.

9. The optical component according to claim 6, wherein, The specular gloss G(20) of the reflective sheet at an incident angle of 20°, the specular gloss G(60) of the reflective sheet at an incident angle of 60°, and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: |G(60)-G(85)|<|G(20)-G(60)|.

10. The optical component according to claim 6, wherein, The specular gloss G(20) of the reflective sheet at an incident angle of 20°, the specular gloss G(60) of the reflective sheet at an incident angle of 60°, and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: |G(60)-G(85)| / ((G(60)+G(85)) / 2)<|G(20)-G(60)| / ((G(20)+G(60)) / 2).

11. The optical component according to claim 6, wherein, The diffuse reflectivity of the reflective sheet is above 65% and below 90%.

12. The optical component according to claim 6, wherein, The reflective sheet has a specular gloss of 75 or higher at an incident angle of 85°.

13. The optical component according to claim 6, wherein, The ratio of the specular gloss of the reflective sheet at an incident angle of 85° to the specular gloss of the reflective sheet at an incident angle of 20° is 0.85 or higher.

14. The optical component according to claim 6, wherein, The specular gloss G(20) of the reflective sheet at an incident angle of 20° and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: G(20)-G(85)≤0.

15. The optical component according to claim 6, wherein, The ratio of the specular gloss of the reflective sheet at an incident angle of 85° to the specular gloss of the reflective sheet at an incident angle of 60° is greater than 0.55 and less than 2.

0.

16. The optical component according to claim 6, wherein, The specular gloss G(60) of the reflective sheet at an incident angle of 60° and the specular gloss G(85) of the reflective sheet at an incident angle of 85° satisfy the following relationship: 15≤G(60)-G(85)≤22.

17. A surface light source device, further comprising: The optical component as described in claim 1 or 2; and A light source that emits light incident on the light guide plate.

18. The surface light source device according to claim 17, wherein, The difference in tilt angle (°) between the first element surface and the third element surface is greater than or equal to half the peak and half the width (°) of the angular distribution of brightness at the light-emitting surface.

19. A display device comprising: The surface light source device according to claim 17; and The display panel faces the surface light source device.

Images