JP7157351B2 - Surface light source device, display device and electronic device - Google Patents

Description

The present invention relates to a light guide plate, a surface light source device, a display device, and an electronic device.

As backlight systems for liquid crystal display devices, there are a system called an edge-light backlight and a system called a direct backlight. BACKGROUND ART As a display for a large-sized liquid crystal display device, a direct type backlight is used, which has a high light utilization efficiency and can easily achieve high brightness. As a light source for the backlight, for example, an LED (Light Emitting Diode) that emits white light is used. In the case of a direct type backlight, a plurality of LEDs are arranged directly below the liquid crystal display device, and luminance unevenness is likely to occur in the liquid crystal display device between the portion directly above the LEDs and other portions.

Conventionally, the light source is installed in a conical recess for inserting the light source provided on the back of the light guide plate, and the back of the light guide plate is provided with light scattering dots for scattering the light inside the light guide plate, A surface light source device has been proposed in which at least part of light from a light source is reflected by the front surface and/or the rear surface of the light guide plate and then emitted from the front surface of the light guide plate (for example, Patent Document 1). .

Japanese Patent No. 3427636

Moreover, it has been difficult to reduce the thickness of the light guide plate and suppress unevenness in luminance. In view of such circumstances, it is an object of the present invention to provide a technique for promoting thinning of the light guide plate and suppressing luminance unevenness of the light guide plate.

The light guide plate according to the present invention includes a concave portion provided on the opposite side of the light emitting surface from which light is emitted, and an upper portion in the direction toward the light emitting surface from the light emitting element provided on the opposite side of the light emitting surface and above the concave portion. a first direction changing portion provided inside for changing the traveling direction of at least part of the light from the light emitting element; A second direction changing section is provided for changing the direction of movement of a portion.

In this way, even if the thickness of the light guide plate cannot be increased, the irradiation area of the light from the light emitting elements can be widened and the light distribution can be dispersed so as not to be concentrated right above the light emitting elements. That is, it is possible to promote thinning of the light guide plate and to suppress luminance unevenness.

Also, the first direction changing part and the second direction changing part may be made of a material that blocks, reflects or diffuses light. With such a configuration, luminance unevenness can be suppressed.

Further, an optical film laminated on the light exit surface may be further provided, and the second direction changing part may be provided on the optical film. Specifically, the second direction changing portion may be provided on an optical film such as a diffusion sheet or a prism sheet provided in a general surface light source device.

Further, the first direction changing part is a first diffraction grating formed in the concave portion of the light guide plate, and the second direction changing part is a second diffraction grating formed on the light exit surface, good too. For example, even with such a configuration, luminance unevenness can be suppressed.

In addition, the light guide plate according to the present invention includes a first recess for housing the light emitting element provided on the opposite side of the light emitting surface from which light is emitted, and the first recess has a conical shape, a truncated conical shape, or a pyramidal shape. or a truncated pyramidal shape, and on the light exit surface side of the light guide plate and upward in the direction toward the light exit surface with respect to the first recess, a cone shape, a truncated cone shape, a pyramid shape, a truncated pyramid shape, or A bowl-shaped second recess may be provided.

In this way, even if the thickness of the light guide plate cannot be increased, the light from the light emitting element is refracted or reflected by the side surfaces of the first recess and the side surface of the second recess, and the light is emitted from the light exit surface. The irradiation area by the light of can be expanded. That is, it is possible to promote thinning of the light guide plate and to suppress luminance unevenness.

Also, the first concave portion and the second concave portion may each have a Fresnel lens for diffusing light from the light emitting element. By doing so, it is possible to widen the irradiation area of the light from the light exit surface without increasing the thickness of the light guide plate, and it is possible to suppress luminance unevenness.

Further, the present invention may be provided as a surface light source device including the light guide plate described above and light emitting elements accommodated in recesses. and a display panel for receiving the light emitted from the light. Moreover, the surface light source device may further include a transparent resin layer arranged between the light guide plate and the light emitting element. Further, it may be provided as an electronic device including the display device.

ADVANTAGE OF THE INVENTION According to this invention, while promoting thinning of a light-guide plate, the technique which suppresses the brightness nonuniformity of a liquid crystal display device can be provided.

FIG. 1 is a perspective view illustrating the configuration of a liquid crystal display device. FIG. 2 is a perspective view illustrating the configuration of the surface light source device. 3A is a cross-sectional view schematically showing the light guide plate according to Embodiment 1. FIG. 3B is a cross-sectional view schematically showing the light guide plate according to Embodiment 1. FIG. FIG. 4 is a cross-sectional view schematically showing a light guide plate according to Embodiment 2. FIG. FIG. 5 is a cross-sectional view schematically showing a light guide plate according to Embodiment 3. FIG. FIG. 6 is a cross-sectional view schematically showing a light guide plate according to Embodiment 4. FIG. 7 is a cross-sectional view schematically showing a light guide plate according to Embodiment 5. FIG. FIG. 8 is a cross-sectional view schematically showing a light guide plate according to Embodiment 6. FIG. 9 is a cross-sectional view schematically showing a light guide plate according to Embodiment 7. FIG. 10 is a cross-sectional view schematically showing a light guide plate according to Embodiment 8. FIG. 11 is a cross-sectional view schematically showing a light guide plate according to Embodiment 9. FIG. FIG. 12 is a cross-sectional view schematically showing a light guide plate according to the tenth embodiment. 13 is a cross-sectional view schematically showing a light guide plate according to Embodiment 11. FIG. 14 is a cross-sectional view schematically showing a light guide plate according to Embodiment 12. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the embodiment described below shows an example of carrying out the present invention, and does not limit the present invention to the specific configuration described below.

In the following embodiments, the "display device" will be explained as a liquid crystal display device, and the "surface light source device" will be explained as a backlight of the liquid crystal display device.

(Structure of liquid crystal display device)
FIG. 1 is a perspective view illustrating the configuration of a liquid crystal display device. As shown in FIG. 1 , the liquid crystal display device includes a surface light source device 1 arranged as a backlight, and a display panel 2 that receives light emitted from the surface light source device 1 . The display panel 2 displays an image by increasing or decreasing light transmittance by applying a voltage to liquid crystal enclosed between glass plates. In the following description, the display panel 2 side of the surface light source device 1 is sometimes referred to as the upper surface side, and the opposite surface side thereof is referred to as the lower surface side. That is, the light emitting surface side of the surface light source device 1 is called the upper side.

(Structure of surface light source device)
FIG. 2 is a perspective view illustrating the configuration of the surface light source device 1. FIG. A surface light source device 1 includes a light guide plate 10 and a frame 12 . The surface light source device 1 also includes a plurality of light sources 11 arranged on the lower surface side of the light guide plate 10, a mounting substrate 13, and a reflective layer . The lower surface side of the light guide plate 10 is the side opposite to the side on which the display panel 2 is arranged. Further, the surface light source device 1 includes a diffusion sheet 15 , a prism sheet 16 and a light shielding member 17 that are laminated in order on the upper surface side of the light guide plate 10 . The upper surface side of the light guide plate 10 is the side on which the display panel 2 is arranged. The number of prism sheets 16 may be one or plural.

The light guide plate 10 has a substantially flat plate shape and is made of translucent material such as polycarbonate resin or polymethyl methacrylate (acrylic) resin. The upper surface of the light guide plate 10 is a light emitting surface from which light is emitted, and faces the display panel 2 . The light guide plate 10 guides the light incident on the light guide plate 10 to the light exit surface so that the entire light exit surface is illuminated uniformly.

The light source 11 emits white light from an emission surface. The light source 11 is, for example, an LED package, but a light source other than the LED package may be used. The light source 11 is formed by sealing an LED chip, which is a light-emitting element (light-emitting portion), with a translucent resin (resin layer) containing a phosphor. The phosphor layer may be placed on the light exit surface of the light guide plate 10 without placing the phosphor on the LED chip, or the phosphor layer may be placed on the diffusion sheet 15 . The light source 11 is driven by power supplied from the mounting board 13 . As the light source 11, an LED light source other than white may be used. The light source 11 is arranged below the light guide plate 10 .

The frame 12 is a frame-shaped member (also referred to as a “frame body”) having an opening and having four sides. The frame 12 is made of polycarbonate resin containing titanium oxide or polycarbonate resin containing no titanium oxide. The light guide plate 10 is fitted in the frame 12 , and the inner peripheral surface of the frame 12 surrounds the side surface forming the outer peripheral surface of the light guide plate 10 . The frame 12 has a high reflectance and reflects and reuses the light leaking from the side surface of the light guide plate 10 . The mounting board 13 is a wiring board in which wiring is provided by a conductive foil on an insulating base material.

A plurality of light sources 11 and reflective layers 14 are provided on the mounting substrate 13 . A reflective layer 14 is provided around the light source 11 . The reflective layer 14 is, for example, white resin or metal foil with high reflectance, and reflects light so that the light in the light guide plate 10 does not leak from the bottom surface of the surface light source device 1 . The diffusion sheet 15 is a translucent resin film, and diffuses the light emitted from the light exit surface of the light guide plate 10 to widen the directivity of the light. The prism sheet 16 is a transparent resin film having a triangular prism-like fine pattern formed on its upper surface. Increase brightness.

The light shielding member 17 has a frame shape when the surface light source device 1 is viewed from above. The frame shape may be a closed loop shape, and may be, for example, a rectangular shape, a substantially elliptical shape, or other shapes other than these. The light shielding member 17 may be, for example, a black adhesive tape having adhesive surfaces on both upper and lower surfaces. A frame portion of the light shielding member 17 is adhered along the upper end of the frame 12 to suppress leakage of light from the surface light source device 1 .

<Embodiment 1>
FIG. 3A is a cross-sectional view schematically showing the light guide plate 10. FIG. The light guide plate 10 has a plurality of recesses 20 on the bottom surface of the light guide plate 10 . That is, the recessed portion 20 is a recess that opens downward in the light guide plate 10 and is recessed upward. A plurality of light sources 11 are arranged on the mounting board 13 , and one light source 11 is accommodated in each recess 20 . In addition, the recessed part 20 is also called an accommodating part. Light emitted from the light source 11 enters the light guide plate 10 . The light incident on the light guide plate 10 is refracted, reflected, and diffused within the light guide plate 10 and emitted from the light exit surface of the light guide plate 10, so that the light exit surface of the light guide plate 10 shines uniformly. The thickness (height) t1 of the light guide plate 10 and the pitch d1 between the light sources 11 are arbitrary values. Optical films such as a diffusion sheet 15 and a prism sheet 16 are laminated on the light exit surface, which is the upper surface side of the light guide plate 10 . The size ratio of each component is not limited to the illustrated example.

The recess 20 has a truncated cone shape, and the diameter of the recess 20 narrows from the opening (lower side) of the recess 20 toward the back (upper end) of the recess 20 . The diameter of the bottom surface (upper end) of the recess 20 and the height (depth) of the recess 20 are arbitrary values, and the shape and size of the recess 20 are not particularly limited. For example, instead of a truncated cone, a bell shape with a curved surface at the far end of the recess 20 or a cone shape may be used. Also, the shape, height and width of the light source 11 are not particularly limited as long as the shape and size of the light source 11 are accommodated in the recess 20 .

Further, the surface light source device 1 according to the present embodiment includes direction changing portions that change the traveling direction of the light emitted from the light source 11 on the concave portion 20 and the light emitting surface. Specifically, the first direction changing portion 30 is provided near the line passing through the light source 11 and perpendicular to the light exit surface, which is the end portion at the back of the recess 20 . Further, a second direction changer 40 is provided on the light exit surface and near the foot of the perpendicular line drawn from the light source 11 to the light exit surface. The first redirecting portion 30 and the second redirecting portion 40 are made of a material that blocks, reflects or diffuses light, respectively. Also, the first direction changing portion 30 and the second direction changing portion 40 may be formed by coating with ink having predetermined properties such as blocking, reflecting, and diffusing light.

FIG. 3B is a diagram for explaining the path of light according to this embodiment. For example, the light source 11 has the highest luminous intensity in the direction directly above it. As indicated by the thick solid arrow in FIG. 3B, the light emitted from the light source 11 in the upward direction enters the first direction changing section 30 and is blocked, reflected, or diffused. Also, the light that has passed through the first direction changing portion 30 is further incident on the second direction changing portion 40 and is blocked, reflected, or diffused.

In particular, when the distance from the light source 11 to the display panel 2, which is the light irradiation surface, is short, it is difficult to make the illuminance on the display panel 2 uniform, and the illuminance tends to be higher the closer the light source 11 is. According to the first direction changing unit 30 and the second direction changing unit 40 shown in FIG. 3A, it is possible to block, reflect, or diffuse straight light directly upward from the light source 11, thereby suppressing the occurrence of luminance unevenness. be able to Note that the direction changing portion 30 and the direction changing portion 40 may be provided at a portion corresponding to the peak of the luminous intensity of the light emitted from the light source 11 .

<Embodiment 2>
FIG. 4 is a cross-sectional view schematically showing the light guide plate 10 according to the second embodiment. The size ratio of each component is not limited to the illustrated example. In this embodiment, constituent elements corresponding to the above configuration are denoted by corresponding reference numerals, and descriptions thereof are omitted.

The light guide plate 10 according to this embodiment also has two direction changing portions. Specifically, the first direction changing portion 30 is provided near the line passing through the light source 11 and perpendicular to the light exit surface, which is the end portion at the back of the recess 20 . A second direction changer 40 is provided between the diffusion sheet 15 and the prism sheet 16 and near the foot of the vertical line extending from the light source 11 to the diffusion sheet 15 or the prism sheet 16 . Summarizing the first and second embodiments, the first direction changing section 30 and the second direction changing section 40 are provided directly above the light source 11 . In other words, at least part of the light from the light source 11 has a first direction changing portion and a second direction changing portion that change the traveling direction of the light in two stages. Also, the first direction changing part 30 and the second direction changing part 40 are made of a material that blocks, reflects or diffuses light, respectively. The first direction changing portion 30 and the second direction changing portion 40 according to this embodiment may also be formed by applying ink having predetermined characteristics.

The first direction changing unit 30 and the second direction changing unit 40 shown in FIG. 4 can also block, reflect, or diffuse straight light directly upward from the light source 11, thereby suppressing the occurrence of luminance unevenness. will be able to Note that the first direction changing section 30 and the second direction changing section 40 may be provided at positions other than those shown in FIG. 4 as long as they are directly above the light source 11 . For example, the second direction changer 40 may be provided on the prism sheet 16 .

<Embodiment 3>
FIG. 5 is a cross-sectional view schematically showing the light guide plate 10 according to the third embodiment. The size ratio of each component is not limited to the illustrated example. In this embodiment, constituent elements corresponding to the above configuration are denoted by corresponding reference numerals, and descriptions thereof are omitted.

A concave portion 20 in FIG. 5 is a truncated conical concave portion provided in the light guide plate 10 and serves as a through hole. In addition, the diameter of the recess 20 narrows from the opening on the bottom side toward the opening on the top side. That is, the accommodating portion of the light source 11 according to this embodiment is a through hole with a tapered side surface.

A light diffusion layer 50 made of a diffusion material that diffuses light is provided on the light exit surface side (upper surface side) of the light guide plate 10 . The diffusing material is, for example, a resin molding in which particles having random sizes and different refractive indices are dispersed therein, and diffuses the light emitted from the light exit surface of the light guide plate 10 to improve the directivity of the light. spread. Further, the light diffusion layer 50 has a plurality of truncated cone-shaped protrusions 51 , and each of the protrusions 51 is inserted into the recess 20 of the light guide plate 10 . A diffusion sheet 15 and a prism sheet 16 (not shown) are laminated on the upper surface side of the light diffusion layer 50 .

In the surface light source device shown in FIG. 5, the light guide plate 10 is combined with the light diffusion layer 50 formed of a material different from the light guide plate 10 formed of polycarbonate, acrylic, or the like. With such a configuration, the light from the light source 11 can be refracted by the side surface 21 of the recess 20 in the direction of diffusion, and the light incident on the light diffusion layer 50 can be further diffused. Also, the convex portion 51 of the light diffusion layer 50 is positioned almost directly above the light source 11 . By increasing the thickness almost directly above the light source 11 where the luminance tends to be the highest and by refracting the light on the side surface of the truncated cone-shaped projection 51, it is possible to suppress the occurrence of luminance unevenness. . Further, when the light guide plate 10 and the light diffusion layer 50 shown in FIG. 5 are integrally molded without being divided into two parts, a mold having the same shape as the concave portion 20 is used. The shape of the recess 20 is pointed at its upper end, but such a shape is easily damaged and difficult to maintain the diffusion performance of the integrally molded part. Thus, there is an advantage of forming with two parts.

<Embodiment 4>
FIG. 6 is a cross-sectional view schematically showing the light guide plate 10 according to the fourth embodiment. The size ratio of each component is not limited to the illustrated example. Although only one recess 22 is shown in the example of FIG. 6, the light guide plate 10 is provided with a plurality of recesses 22 and the like at a predetermined pitch. In this embodiment, constituent elements corresponding to the above configuration are denoted by corresponding reference numerals, and descriptions thereof are omitted.

The surface light source device shown in FIG. 6 is a cylindrical depression with one bottom surface open, and includes a concave portion 22 serving as a housing portion for housing the light source 11 . The diameter of the bottom surface of the recess 22 and the height (depth) of the recess 22 are arbitrary values. For example, it may be a prism, a truncated cone, or other shape instead of a cylinder. Also, the shape, height and width of the light source 11 are not particularly limited as long as the shape and size of the light source 11 are accommodated in the recess 22 .

The light guide plate 10 according to this embodiment has a first diffraction grating 60 and a second diffraction grating 70 almost directly above the light source 11 . The first diffraction grating 60 is provided at the far end of the recess 22 . The second diffraction grating 70 is provided on the light exit surface side of the light guide plate 10 . Also, the first diffraction grating 60 and the second diffraction grating 70 are provided concentrically in a plan view seen from above the light exit surface side. Note that the first diffraction grating 60 and the second diffraction grating 70 may have the same shape. In this embodiment, the first diffraction grating 60 and the second diffraction grating 70 each have a predetermined diffraction angle and are provided so as to widen the irradiation area of the light from the light source 11 . That is, by providing diffraction gratings at appropriate pitches, the direction in which light from the light source 11 is diffracted is controlled, and the irradiation area on the display panel 2 is widened.

With the configuration shown in this embodiment as well, the light from the light source 11 can be diffused and applied to the display panel 2 . In this way, it is possible to suppress the occurrence of luminance unevenness even by adopting a configuration in which the traveling direction of light is changed in two steps.

Embodiments 1 to 4 are provided with some kind of direction changing part for changing the traveling direction of at least part of the light from the light source 11 inside the concave part that houses the light source 11 and at two places above the light exit surface. there is In this way, even if the thickness of the light guide plate cannot be increased, the irradiation area of the light from the light source 11 can be widened and the light distribution can be dispersed so as not to be concentrated right above the light source 11.例文帳に追加That is, it is possible to promote thinning of the light guide plate and to suppress luminance unevenness of the liquid crystal display device.

<Embodiment 5>
FIG. 7 is a cross-sectional view schematically showing the light guide plate 10 according to the fifth embodiment. The size ratio of each component is not limited to the illustrated example. Although only one recess 23 is shown in the example of FIG. 7, the light guide plate 10 is provided with a plurality of recesses 23 and the like at a predetermined pitch. In this embodiment, constituent elements corresponding to the above configuration are denoted by corresponding reference numerals, and descriptions thereof are omitted.

The light guide plate 10 shown in FIG. 7 is a conical depression with an open bottom, and includes a recess 23 serving as a housing portion for housing the light source 11 . The diameter of the bottom surface of the recess 23 and the height (depth) of the recess 23 are arbitrary values. The concave portion 23 may have a truncated cone shape, a pyramid shape, a truncated pyramid shape, or the like. Also, the shape, height and width of the light source 11 are not particularly limited as long as the shape and size of the light source 11 are accommodated in the recess 23 .

In addition, on the light emitting surface side of the light guide plate 10, a concave portion 80, which is a conical concave portion, is provided almost directly above the light source 11. As shown in FIG. The diameter of the bottom surface of the recess 80 and the height (depth) of the recess 80 are also arbitrary values. Alternatively, the recess 80 may have a truncated cone shape.

According to the light guide plate 10 according to the present embodiment, part of the light from the light source 11 that is incident on the side surface 24 of the recess 23 and refracted is further incident on the side surface 81 of the recess 80 and refracted, or It can be reflected. Also in this embodiment, the recesses 23 and the recesses 80 are provided so as to widen the irradiation area of the light from the light source 11 .

With the configuration shown in this embodiment as well, the light from the light source 11 can be diffused and applied to the display panel 2 . In this way, it is possible to suppress the occurrence of luminance unevenness even by adopting a configuration in which the traveling direction of light is changed in two steps.

<Embodiment 6>
FIG. 8 is a schematic cross-sectional view of the light guide plate 10 according to the sixth embodiment. The size ratio of each component is not limited to the illustrated example. Although only one recess 25 is shown in the example of FIG. 8, the light guide plate 10 is provided with a plurality of recesses 25 and the like at a predetermined pitch. In this embodiment, constituent elements corresponding to the above configuration are denoted by corresponding reference numerals, and descriptions thereof are omitted.

The surface light source device shown in FIG. 8 is a cone-shaped recess with an open bottom, and includes a recess 25 serving as a housing portion for housing the light source 11 . The diameter of the bottom surface of the recess 25 and the height (depth) of the recess 25 are arbitrary values. The concave portion 25 may have a truncated cone shape, a pyramid shape, a truncated pyramid shape, or the like. Also, the shape, height and width of the light source 11 are not particularly limited as long as the shape and size of the light source 11 are accommodated in the recess 23 . Fresnel lens-like unevenness 26 is formed on the side surface of the concave portion 25 according to the present embodiment. The unevenness 26 is formed so as to cover almost right above the light source 11 , and changes the traveling direction of the light emitted from the light source 11 so as to widen the irradiation area to the display panel 2 .

Further, the light exit surface side of the light guide plate 10 is provided with a concave portion 90 which is a bowl-shaped concave portion formed by a curved surface. Fresnel lens-shaped unevenness 91 is formed on a part of the surface of the recess 90 . The unevenness 91 is also formed so as to cover almost directly above the light source 11, and changes the traveling direction of the light emitted by the light source 11 so as to widen the irradiation area to the display panel 2 (not shown). That is, the unevenness 91 changes the direction in which the light from the light source 11 is refracted to a steeper angle, and widens the irradiation area on the display panel 2 .

With the configuration shown in this embodiment as well, the light from the light source 11 can be diffused and applied to the display panel 2 . In this way, it is possible to suppress the occurrence of luminance unevenness even by adopting a configuration in which the traveling direction of light is changed in two stages. Further, a Fresnel lens may be provided on a plane parallel to the display panel 2 on at least one of the light emitting surface side of the light guide plate 10 and the light source 11 side. By doing so, the thickness of the light guide plate 10 can be reduced.

<Embodiment 7>
FIG. 9 is a cross-sectional view schematically showing the light guide plate 10 according to the seventh embodiment. The size ratio of each component is not limited to the illustrated example. Also in the present embodiment, constituent elements corresponding to the configuration described above are denoted by corresponding reference numerals, and descriptions thereof are omitted.

The light source 11 may be covered with a transparent resin layer 18, for example. In the example of FIG. 9, a transparent resin layer 18 is arranged between the light guide plate 10 and the plurality of light sources 11 and the reflective layer 14 . In other words, multiple light sources 11 are embedded in the transparent resin layer 18 . Also, the light guide plate 10 is arranged on the transparent resin layer 18 and the light source 11 is not accommodated in the concave portion 20 of the light guide plate 10 . Further, the lower surface of the light guide plate 10 is in contact with the transparent resin layer 18, and the lower surface of the light guide plate 10 and the reflective layer 14 are not in contact. The upper surface of the transparent resin layer 18 is flat and in contact with the light guide plate 10 . Light emitted from the light source 11 passes through the transparent resin layer 18 and enters the light guide plate 10 .

In this embodiment, a first direction changer 30 and a second direction changer 40 are provided at the same positions as in the second embodiment. With such a configuration as well, it is possible to block, reflect, or diffuse straight light directly upward from the light source 11, thereby suppressing the occurrence of luminance unevenness. Also, the luminous flux directed directly above the light source 11 spreads as it travels in the transparent resin layer 18, is refracted when emitted to the lower surface of the light guide plate 10, and is further diffused. The first direction changing portion 30 or the second direction changing portion 40 may be provided in the transparent resin layer 18 .

<Embodiment 8>
FIG. 10 is a cross-sectional view schematically showing the light guide plate 10 according to the eighth embodiment. The size ratio of each component is not limited to the illustrated example. Also in the present embodiment, constituent elements corresponding to the configuration described above are denoted by corresponding reference numerals, and descriptions thereof are omitted.

In the example of FIG. 10 as well, the light source 11 is embedded in the transparent resin layer 18 . It can be said that such a configuration also has the transparent resin layer 18 arranged between the light guide plate 10 and the plurality of light sources 11 and the reflective layer 14 . The transparent resin layer 18 is arranged below the light guide plate 10 , and the light source 11 is not accommodated in the recess 20 of the light guide plate 10 . Also, the lower surface of the light guide plate 10 and the reflective layer 14 are not in contact with each other. Moreover, the lower surface of the light guide plate 10 and the transparent resin layer 18 may be in contact with each other, or may be in non-contact with each other. The transparent resin layer 18 shown in FIG. 10 has a substantially hemispherical shape, but is not limited to this shape. There may be. In addition, part of the transparent resin layer 18 may enter the concave portion 20 of the light guide plate 10 , or the transparent resin layer 18 may not enter the concave portion 20 of the light guide plate 10 . Also, the transparent resin layer 18 may be in contact with the interior of the recess 20 . Light emitted from the light source 11 passes through the transparent resin layer 18 and enters the light guide plate 10 .

Also in this embodiment, the first direction changing portion 30 and the second direction changing portion 40 are provided at the same positions as in the second embodiment. With such a configuration as well, it is possible to block, reflect, or diffuse straight light directly upward from the light source 11, thereby suppressing the occurrence of luminance unevenness. Also, the luminous flux directed directly above the light source 11 travels while spreading within the transparent resin layer 18, is refracted when emitted from the transparent resin layer 18, and is further diffused. The first direction changing portion 30 or the second direction changing portion 40 may be provided in the transparent resin layer 18 .

<Embodiment 9>
FIG. 11 is a cross-sectional view schematically showing the light guide plate 10 according to the ninth embodiment. The size ratio of each component is not limited to the illustrated example. Also in the present embodiment, constituent elements corresponding to the configuration described above are denoted by corresponding reference numerals, and descriptions thereof are omitted.

The light source 11 is embedded in the transparent resin layer 18 also in the example of FIG. The transparent resin layer 18 has, for example, a substantially hemispherical shape that protrudes upward, and has a donut shape in which the vicinity of the center in a plan view is depressed and the periphery protrudes upward in a ring shape. Moreover, the shape which two substantially hemispherical shapes connected may be sufficient. The transparent resin layer 18 is arranged below the light guide plate 10 , and the light source 11 is not accommodated in the recess 20 of the light guide plate 10 . The lower surface of the light guide plate 10 and the reflective layer 14 are not in contact with each other. Moreover, the lower surface of the light guide plate 10 and the transparent resin layer 18 may be in contact with each other, or may be in non-contact with each other. In addition, part of the transparent resin layer 18 may enter the concave portion 20 of the light guide plate 10 , or the transparent resin layer 18 may not enter the concave portion 20 of the light guide plate 10 . Also, the transparent resin layer 18 may be in contact with the interior of the recess 20 . Light emitted from the light source 11 passes through the transparent resin layer 18 and enters the light guide plate 10 .

Also in this embodiment, the first direction changing portion 30 and the second direction changing portion 40 are provided at the same positions as in the second embodiment. With such a configuration as well, it is possible to block, reflect, or diffuse straight light directly upward from the light source 11, thereby suppressing the occurrence of luminance unevenness. Also, the luminous flux directed directly above the light source 11 travels while spreading within the transparent resin layer 18, is refracted when emitted from the transparent resin layer 18, and is further diffused. The first direction changing portion 30 or the second direction changing portion 40 may be provided in the transparent resin layer 18 .

<Embodiment 10>
FIG. 12 is a cross-sectional view schematically showing the light guide plate 10 according to the tenth embodiment. The size ratio of each component is not limited to the illustrated example. Also in the present embodiment, constituent elements corresponding to the configuration described above are denoted by corresponding reference numerals, and descriptions thereof are omitted.

The light source 11 is embedded in the transparent resin layer 18 also in the example of FIG. It can be said that such a configuration also has the transparent resin layer 18 arranged between the light guide plate 10 and the plurality of light sources 11 and the reflective layer 14 . The transparent resin layer 18 is accommodated in the recess 20 below the light guide plate 10 . Moreover, the lower surface of the light guide plate 10 and the transparent resin layer 18 may be in contact with each other, or may be in non-contact with each other. The transparent resin layer 18 shown in FIG. 10 has a substantially hemispherical shape, but is not limited to this shape. There may be. Also, the transparent resin layer 18 may be in contact with the interior of the recess 20 . Light emitted from the light source 11 passes through the transparent resin layer 18 and enters the light guide plate 10 .

Also in this embodiment, the first direction changing portion 30 and the second direction changing portion 40 are provided at the same positions as in the second embodiment. With such a configuration as well, it is possible to block, reflect, or diffuse straight light directly upward from the light source 11, thereby suppressing the occurrence of luminance unevenness. Also, the luminous flux directed directly above the light source 11 travels while spreading within the transparent resin layer 18, is refracted when emitted from the transparent resin layer 18, and is further diffused. The first direction changing portion 30 or the second direction changing portion 40 may be provided in the transparent resin layer 18 .

<Embodiment 11>
FIG. 13 is a cross-sectional view schematically showing the light guide plate 10 according to the eleventh embodiment. The size ratio of each component is not limited to the illustrated example. Also in the present embodiment, constituent elements corresponding to the configuration described above are denoted by corresponding reference numerals, and descriptions thereof are omitted.

In the example of FIG. 13 as well, the light source 11 is embedded in the transparent resin layer 18 . It can be said that such a configuration also has the transparent resin layer 18 arranged between the light guide plate 10 and the plurality of light sources 11 and the reflective layer 14 . The transparent resin layer 18 has, for example, a substantially hemispherical shape that protrudes upward, and has a donut shape in which the vicinity of the center in a plan view is depressed and the periphery protrudes upward in a ring shape. Moreover, the shape which two substantially hemispherical shapes connected may be sufficient. The transparent resin layer 18 is arranged below the light guide plate 10 , and the light source 11 is accommodated in the concave portion 20 of the light guide plate 10 . Also, the lower surface of the light guide plate 10 and the reflective layer 14 are in contact with each other. Moreover, the lower surface of the light guide plate 10 and the transparent resin layer 18 may be in contact with each other, or may be in non-contact with each other. Also, the transparent resin layer 18 may be in contact with the interior of the recess 20 . Light emitted from the light source 11 passes through the transparent resin layer 18 and enters the light guide plate 10 .

Also in this embodiment, the first direction changing portion 30 and the second direction changing portion 40 are provided at the same positions as in the second embodiment. With such a configuration as well, it is possible to block, reflect, or diffuse straight light directly upward from the light source 11, thereby suppressing the occurrence of luminance unevenness. Also, the luminous flux directed directly above the light source 11 travels while spreading within the transparent resin layer 18, is refracted when emitted from the transparent resin layer 18, and is further diffused. The first direction changing portion 30 or the second direction changing portion 40 may be provided in the transparent resin layer 18 .

<Embodiment 12>
FIG. 14 is a cross-sectional view schematically showing the light guide plate 10 according to the twelfth embodiment. The size ratio of each component is not limited to the illustrated example. Also in the present embodiment, constituent elements corresponding to the configuration described above are denoted by corresponding reference numerals, and descriptions thereof are omitted.

In FIG. 14, a transparent resin layer 18 is arranged between the light guide plate 10 and the plurality of light sources 11 and the reflective layer 14 . In other words, multiple light sources 11 are embedded in the transparent resin layer 18 . It can be said that such a configuration also has the transparent resin layer 18 arranged between the light guide plate 10 and the plurality of light sources 11 and the reflective layer 14 . Also, the light guide plate 10 is arranged on the transparent resin layer 18 and the light source 11 is not accommodated in the concave portion 20 of the light guide plate 10 . Further, similarly to the fifth embodiment and the like, the light guide plate 10 is provided with the concave portion 23 and the concave portion 80 . The recesses 23 and 80 are conical, pyramidal, bowl-shaped, bell-shaped, or the like. Further, a first direction changing portion 30 is provided at the inner depth portion of the concave portion 23 . A second direction changer 40 is provided between the diffusion sheet 15 and the prism sheet 16 and in the vicinity directly above the light source 11 .

The light guide plate 10 according to the present embodiment has recesses 23 and recesses 80 as in the fifth embodiment. Further, the light guide plate 10 according to the present embodiment has a convex dot pattern 19a on the light exit surface side and a concave dot pattern 19b on the lower surface side. It is assumed that the dot pattern 19a is provided around the concave portion 80 in plan view. Similarly, the dot pattern 19b is provided around the recess 23 in plan view. The dot patterns 19a and 19b may be provided on the light exit surface and the entire lower surface of the light guide plate 10, respectively. The dot pattern 19a has a projection shape such as a convex lens shape, a cylinder shape, a prism shape, a cone shape, a pyramid shape, or the like. The dot pattern 19b has a concave shape such as a concave lens shape, a cylindrical groove shape, a prismatic groove shape, a conical groove shape, a pyramidal groove shape, or the like. The dot patterns 19a and 19b may be circular, elliptical, or polygonal in plan view. Also, the dot patterns 19a and 19b may be formed integrally with the light guide plate 10 when the light guide plate 10 is manufactured by injection molding. Also, the dot patterns 19a and 19b may be separately formed on the light guide plate 10 by inkjet or the like. The dot patterns 19a and 19b can diffuse the light on the lower surface or the light exit surface of the light guide plate 10. FIG. Further, the interior of the recess 23 or the recess 80 may have minute unevenness. By doing so, the light incident on the concave portion 23 or the concave portion 80 can be more diffused.

In this embodiment, a first direction changer 30 and a second direction changer 40 are provided at the same positions as in the second embodiment. With such a configuration as well, it is possible to block, reflect, or diffuse straight light directly upward from the light source 11, thereby suppressing the occurrence of luminance unevenness. Also, the luminous flux directed directly above the light source 11 travels while spreading within the transparent resin layer 18, is refracted when emitted from the transparent resin layer 18, and is further diffused. The first direction changing portion 30 or the second direction changing portion 40 may be provided in the transparent resin layer 18 .

A display device including the light guide plate 10 shown in Embodiments 1 to 6 can be mounted on various electronic devices. Examples of electronic devices equipped with such display devices include smartphones, digital cameras, tablet terminals, electronic books, wearable devices, car navigation devices, electronic dictionaries, and electronic billboards. By using the light guide plate and the display device according to the present invention, it is possible to reduce luminance unevenness while reducing the size and thickness of electronic equipment.

1 Surface light source device 10 Light guide plate 11 Light source 12 Frame 13 Mounting substrate 14 Reflective layer 15 Diffusion sheet 16 Prism sheet 17 Light shielding members 20, 22, 23, 25 Concave portions 21, 24 Side surface 26 Unevenness 30 First direction changing portion 40 Second direction changing portion 50 light diffusion layer 51 convex portion 60 first diffraction grating 70 second diffraction gratings 80 and 90 concave portion 81 side surface 91 unevenness 2 display panel

Claims (7)

a substrate;
a light guide plate having a through hole penetrating from a light emitting surface for emitting light to a surface on the substrate side;
a light source disposed within the through hole;
a reflective layer provided between the substrate and the light guide plate;
a transparent resin layer provided between the reflective layer and the light guide plate;
a light diffusion layer provided in an opening of the through hole on the light exit surface side;
has
The reflective layer is a member made of resin, and extends to the inside of the through hole so as to cover the surface of the substrate in the opening of the through hole on the substrate side ,
a surface of the reflective layer on the light guide plate side is in contact with the transparent resin layer, and a surface of the light guide plate on the reflective layer side is in contact with the transparent resin layer;
A surface light source device , wherein the transparent resin layer is in contact with the light source. 2. The surface light source device according to claim 1, wherein the light diffusing layer has a convex portion that protrudes from an opening of the through hole on the light emitting surface side toward the light source. 3. The surface light source device according to claim 2, wherein the convex portion of the light diffusion layer is positioned directly above the light source. 4. The surface light source device according to claim 1, wherein the light diffusion layer is made of a material different from that of the light guide plate. 5. The surface light source device according to claim 4, wherein the light diffusion layer is formed of a resin member in which particles having different refractive indices are dispersed. a surface light source device according to any one of claims 1 to 5;
a display panel that receives light emitted from the surface light source device;
A display device. An electronic device comprising the display device according to claim 6 .

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