JP7093039B2 - 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.

In recent years, electronic devices have become smaller and thinner. The light guide plate of a liquid crystal display device (liquid crystal display) mounted on such an electronic device is required to be thin. As a backlight method for a liquid crystal display device, there are a method called an edge light type backlight and a method called a direct type backlight. As a backlight for a large-sized liquid crystal display device, a direct-type backlight having high light utilization efficiency and easy to increase the brightness is used. 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 under the light guide plate, but the light guide plate tends to have uneven brightness between the portion directly above the LEDs and other parts. In connection with the above technique, for the purpose of reducing the brightness variation of the light source, the light source is installed in a conical light source insertion recess provided on the back surface of the light guide plate, and on the back surface of the light guide plate. A surface light source device provided with light scattering dots for scattering light inside a light guide plate has been proposed (see Patent Document 1).

Japanese Patent No. 3427636

There is a demand for making the light guide plate thinner and suppressing uneven brightness of the light guide plate. In view of such a situation, it is an object of the present invention to provide a technique for promoting thinning of the light guide plate and suppressing uneven brightness of the light guide plate.

In the present invention, the following means are adopted in order to solve the above problems. That is, the present invention is provided on the light emitting surface that emits light, the opposite surface on the opposite side of the light emitting surface, the concave portion provided on the opposite surface, and the light emitting surface, the opposite surface, and the bottom surface of the concave portion to refract the light. The recess is a light guide plate having a plurality of scattering portions and a tapered surface extending from the bottom surface of the recess toward the opening of the recess.

According to the present invention, the light hits the tapered surface, the light is refracted and incident on the light guide plate, so that the light incident on the light guide plate is greatly spread. According to the present invention, light hits the scattering portion provided on the bottom surface of the recess, and the light is refracted and scattered and incident on the light guide plate. According to the present invention, the light in the light guide plate hits the scattering portion provided on the opposite surface, and the light in the light guide plate is refracted and scattered. According to the present invention, the light in the light guide plate hits the scattering portion provided on the light emitting surface, the light in the light guide plate is refracted and scattered, and the light is emitted from the light emitting surface of the light guide plate to the outside. With these configurations, the brightness distribution on the light emitting surface of the light guide plate can be made uniform without increasing the thickness of the light guide plate, and uneven brightness of the light guide plate can be suppressed.

In the light guide plate according to the present invention, a plurality of scattering portions provided on the light emitting surface, the opposite surface, and the bottom surface of the recess are densely arranged. With this configuration, there is a high possibility that the light in the light guide plate and the light emitted from the light emitting surface of the light guide plate are refracted and scattered. Therefore, the brightness distribution of the light emitting surface of the light guide plate is not increased without increasing the thickness of the light guide plate. Is more uniform, and uneven brightness of the light guide plate can be further suppressed.

The light guide plate according to the present invention has a conical trapezoidal shape as a concave portion. With this configuration, a light source of a small size can be accommodated in the recess, so that the brightness distribution on the light emitting surface of the light guide plate is made uniform without increasing the thickness of the light guide plate, and uneven brightness of the light guide plate is suppressed. be able to.

In the light guide plate according to the present invention, the angle of the tapered surface is set according to the angle of the main axis of the light source housed in the recess. With this configuration, even if the main axis of the light source is changed by changing the type of the light source, the incident angle of the light incident on the light emitting surface of the light guide plate can be maintained at a constant angle. In addition, the peak direction of the emitted light of the light source can be controlled. Therefore, the luminance distribution on the light emitting surface of the light guide plate can be controlled for each light source.

The light guide plate according to the present invention is provided with a plurality of recesses on opposite surfaces. With this configuration, the light source can be accommodated in each of the plurality of recesses. The surface light source device according to the present invention includes a light guide plate according to the present invention and a light source housed in a recess, and the angle of the tapered surface is set according to the angle of the main axis of the light source. Since such a surface light source device includes the light guide plate according to the present invention, the brightness distribution on the light emitting surface of the light guide plate is made uniform without increasing the thickness of the light guide plate, and uneven brightness of the light guide plate is suppressed. A surface light source device can be provided.

The surface light source device according to the present invention includes a light guide plate according to the present invention, a light source arranged on the opposite surface side of the light guide plate, and a transparent resin layer arranged between the light guide plate and the light source. Is embedded in the transparent resin layer. Further, in the surface light source device according to the present invention, the light guide plate according to the present invention, a plurality of light sources arranged on the opposite surface side of the light guide plate, and a transparent resin layer arranged between the light guide plate and the plurality of light sources. And, a plurality of light sources are embedded in the transparent resin layer. With these configurations, the distance between the light guide plate and the light source can be kept constant without increasing the thickness of the light guide plate. By separating the light source from the light source without accommodating the light source in the recess of the light guide plate, the spread of the light incident on the light guide plate can be increased. Further, by accommodating the light source and the transparent resin layer in the recess of the light guide plate and increasing the distance between the light source and the light source, the spread of the light incident in the light guide plate can be increased.

The display device according to the present invention includes a surface light source device according to the present invention and a display panel that receives light emitted from the surface light source device. Since such a display device includes the light guide plate and the surface light source device according to the present invention, the brightness distribution on the light emitting surface of the light guide plate is made uniform without increasing the thickness of the light guide plate, and the brightness unevenness of the light guide plate becomes uneven. A suppressed display device can be provided.

The electronic device according to the present invention includes a display device according to the present invention. Since such an electronic device includes the light guide plate, the surface light source device, and the display device according to the present invention, the luminance distribution of the light emitting surface of the light guide plate is made uniform without increasing the thickness of the light guide plate, and the light guide plate It is possible to provide an electronic device in which uneven brightness is suppressed.

According to the present invention, it is possible to promote the thinning of the light guide plate and suppress the uneven brightness of the light guide plate.

FIG. 1 is a perspective view illustrating the configuration of the liquid crystal display device according to the embodiment. FIG. 2 is a perspective view illustrating the configuration of the surface light source device according to the embodiment. FIG. 3 is a cross-sectional view of the light guide plate. FIG. 4A is an enlarged cross-sectional view of the light guide plate. FIG. 4B is an enlarged cross-sectional view of the light guide plate. FIG. 4C is an enlarged cross-sectional view of the light guide plate. FIG. 5A is a plan view of the light guide plate. FIG. 5B is a plan view of the light guide plate. 6A and 6B are cross-sectional views of the light guide plate. FIG. 7 is an enlarged cross-sectional view of the light guide plate. 8 (A) and 8 (B) are views showing the relationship between the angle of the main axis of the light source and the angle of the tapered surface of the recess. FIG. 9 is a diagram showing the progress of light when light is emitted from the light source within a range of about ± 20 degrees with respect to the angle of the main axis of the light source. FIG. 10A is a cross-sectional view of the light guide plate 10. FIG. 10B is a cross-sectional view of the light guide plate 10. FIG. 10C is a cross-sectional view of the light guide plate 10. FIG. 10D is a cross-sectional view of the light guide plate 10. FIG. 10E is a cross-sectional view of the light guide plate 10. FIG. 10F is a cross-sectional view of the light guide plate 10. FIG. 10G is a cross-sectional view of the light guide plate 10.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the embodiments described below show an example of carrying out the present invention, and the present invention is not limited to the specific configuration described below.

In the following embodiments, the "display device" is described as a liquid crystal display device, and the "surface light source device" is described as a backlight of the liquid crystal display device. The "surface light source device" may be used for purposes other than the backlight, such as a front light arranged on the front surface of a display panel or an electronic paper display device.

(Configuration of liquid crystal display device)
FIG. 1 is a perspective view illustrating the configuration of the liquid crystal display device according to the embodiment. 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 applying a voltage to a liquid crystal sandwiched between glass plates to increase or decrease the light transmittance. Hereinafter, in the surface light source device 1, the display panel 2 side may be described as the upper surface side, and the opposite surface side thereof may be described as the lower surface side.

(Structure of surface light source device 1)
FIG. 2 is a perspective view illustrating the configuration of the surface light source device 1 according to the embodiment. The surface light source device 1 includes a light guide plate 10 and a frame 12. Further, the surface light source device 1 includes a plurality of light sources 11, a mounting substrate 13, and a reflection layer 14 arranged on the lower surface side of the light guide plate 10. The lower surface side of the light guide plate 10 is the opposite side 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 which are sequentially laminated 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 prism sheet 16 may be one sheet or a plurality of prism sheets 16.

The light guide plate 10 has a substantially flat plate shape, and is formed of a translucent material such as a polycarbonate resin or a polymethylmethacrylate resin. The upper surface of the light guide plate 10 is a light emitting surface from which light is emitted, and is a surface facing the display panel 2. The light guide plate 10 guides the light incident on the light guide plate 10 to the light emitting surface so that the entire light emitting surface shines uniformly.

The light source 11 emits white light from the exit 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, with a translucent resin (resin layer) containing a phosphor. Alternatively, the phosphor layer may be arranged on the light emitting surface of the light guide plate 10 without arranging the phosphor on the LED chip, or the phosphor layer may be arranged on the diffusion sheet 15. The light source 11 is driven by receiving 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 has an opening and is a frame-shaped member having four sides (an example of a "frame body"). The frame 12 is formed of a polycarbonate resin containing titanium oxide, a polycarbonate resin not containing titanium oxide, or the like. The light guide plate 10 is fitted into 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 leaked from the side surface of the light guide plate 10. The mounting substrate 13 is a wiring board in which wiring is provided by a conductor foil on an insulating base material.

A plurality of light sources 11 and a reflective layer 14 are provided on the mounting substrate 13. The reflective layer 14 is provided around the light source 11. The reflective layer 14 is, for example, a white resin or a metal foil having a high reflectance, and reflects the light in the light guide plate 10 so as not to leak from the lower 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 emitting surface of the light guide plate 10 to expand the directivity of the light. The prism sheet 16 is a transparent resin film having a fine triangular prism-like pattern formed on the upper surface, collects the light diffused by the diffusion sheet 15, and has the brightness when the surface light source device 1 is viewed from the upper surface side. To raise.

The light-shielding member 17 has a frame shape when the surface light source device 1 is viewed from the upper surface side. The frame shape may be a closed loop shape, for example, a rectangular shape, a substantially elliptical shape, or any other shape. The light-shielding member 17 may be, for example, a black adhesive tape having both upper and lower surfaces as adhesive surfaces. The frame portion of the light-shielding member 17 is adhered along the upper end of the frame 12 to prevent light from leaking from the surface light source device 1.

FIG. 3 is a cross-sectional view of the light guide plate 10. The light guide plate 10 has a plurality of recesses 20 on the lower surface of the light guide plate 10. The recess 20 has a conical trapezoidal shape. A plurality of light sources 11 are arranged on the mounting board 13, and one light source 11 is housed in each recess 20. Since the recess 20 has a conical trapezoidal shape, a small size light source 11 can be accommodated in the recess 20. The light emitted from the light source 11 is incident on the light guide plate 10. The light incident on the light guide plate 10 is refracted, reflected and diffused in the light guide plate 10 and emitted from the light emitting surface of the light guide plate 10, so that the light emitting surface of the light guide plate 10 shines uniformly. The thickness (height) t1 of the light guide plate 10 is, for example, 0.35 mm, but the value is not limited to this value and may be another value. The pitch d1 of the light source 11 is, for example, 2 to 4 mm, but is not limited to these values and may be another value.

FIG. 4A is an enlarged cross-sectional view of the light guide plate 10. The light guide plate 10 includes an incoming surface 30 through which light enters, an outgoing surface 31 that emits light incident from the incoming light surface 30, and an opposite surface 32 on the opposite side of the light emitting surface 31. The opposite surface 32 of the light guide plate 10 is the lower surface of the light guide plate 10. A recess 20 is provided on the opposite surface 32 of the light guide plate 10. The recess 20 has a bottom surface 21, an opening 22, and a tapered surface (diameter slope) 23 extending from the bottom surface 21 toward the opening 22. The tapered surface 23 is a smooth surface. The light emitting surface 31 and the opposite surface 32 of the light guide plate 10 are parallel to the bottom surface 21 of the recess 20. The diameter of the recess 20 increases from the bottom surface 21 of the recess 20 toward the opening 22. The diameter of the bottom surface 21 of the recess 20 is, for example, Φ0.43 mm, but the diameter is not limited to this value and may be another value. The height (depth) of the recess 20 is, for example, 0.32 mm, but the value is not limited to this value and may be another value. The shape, height and width of the light source 11 are not particularly limited, and the light source 11 may have a shape and size accommodated in the recess 20. Further, the size of the recess 20 may be changed according to the shape, height and width of the light source 11.

FIG. 4B is an enlarged cross-sectional view of the light guide plate 10. As shown in FIG. 4B, the conical trapezoidal recess 2
The internal angle of 0 may be R-shaped. 4C is an enlarged cross-sectional view of the light guide plate 10. As shown in FIG. 4C, the bottom surface 21 of the conical trapezoidal recess 20 may be R-shaped. That is, the bottom surface 21 of the conical trapezoidal recess 20 may be a curved surface.

The light emitted from the light source 11 hits the tapered surface 23 of the recess 20 and is refracted to enter the light guide plate 10. The light in the light guide plate 10 is incident on the light emitting surface 31 and the opposite surface 32 of the light guide plate 10. When the light incident on the light emitting surface 31 of the light guide plate 10 is incident at an incident angle smaller than the critical angle, the light is emitted to the outside from the light emitting surface 31 of the light guide plate 10. When the light incident on the light emitting surface 31 of the light guide plate 10 is incident at an incident angle larger than the critical angle, the light is reflected by the light emitting surface 31 of the light guide plate 10. When the light incident on the opposite surface 32 of the light guide plate 10 is incident at an incident angle smaller than the critical angle, the light is emitted to the outside from the opposite surface 32 of the light guide plate 10. The light emitted from the opposite surface 32 of the light guide plate 10 is reflected by the reflection layer 14 and is re-entered into the light guide plate 10. When the light incident on the opposite surface 32 of the light guide plate 10 is incident at an incident angle larger than the critical angle, the light is reflected by the opposite surface 32 of the light guide plate 10.

A plurality of dot patterns 41 are provided on the light emitting surface 31 of the light guide plate 10. A plurality of dot patterns 42 are provided on the opposite surface 32 of the light guide plate 10. The light in the light guide plate 10 is refracted and scattered by hitting the dot pattern 41 provided on the light emitting surface 31 of the light guide plate 10 and the dot pattern 42 provided on the opposite surface 32 of the light guide plate 10. A plurality of dot patterns 43 are provided on the bottom surface 21 of the recess 20. The light emitted from the light source 11 hits the dot pattern 43 provided on the bottom surface 21 of the recess 20, is refracted and scattered, and is incident on the light guide plate 10. The dot patterns 41 to 43 are examples of the scattering portion.

The dot pattern 41 shown in FIG. 4 has a protrusion shape (convex shape) protruding to the outside of the light guide plate 10, but is not limited to this shape, and the dot pattern 41 has a concave shape recessed inside the light guide plate 10. There may be. The dot patterns 42 and 43 shown in FIG. 4 have a concave shape that is recessed inside the light guide plate 10, but the dot patterns 42 and 43 are not limited to this shape, and the dot patterns 42 and 43 have a protrusion shape that protrudes to the outside of the light guide plate 10. It may have a convex shape). The protrusion shape is, for example, a convex lens shape, a cylindrical shape, a prismatic shape, a conical shape, a pyramid shape, or the like. The concave shape is, for example, a concave lens shape, a cylindrical groove shape, a prismatic groove shape, a conical groove shape, a pyramid groove shape, or the like. The dot patterns 41 to 43 may be circular, elliptical, or polygonal in a plan view. The dot patterns 41 to 43 may be integrally formed with the light guide plate 10 manufactured by injection molding. Further, the dot patterns 41 to 43 may be separately formed on the light guide plate 10 by inkjet or the like. The surface of the dot patterns 41 to 43 may have minute irregularities. By forming minute irregularities on the surface of the dot patterns 41 to 43, the light hitting the dot patterns 41 to 43 can be more refracted and scattered.

The plurality of dot patterns 41 to 43 are densely arranged. The plurality of dot patterns 41 to 43 may be arranged discretely, but in order to enhance the effect of refraction and scattering of the light in the light guide plate 10 and the light emitted from the light emitting surface 31 of the light guide plate 10, a plurality of dot patterns 41 to 43 may be arranged discretely. It is preferable that the dot patterns 41 to 43 are densely arranged. For example, as shown in FIG. 5A, a plurality of dot patterns 41 may be arranged closest to each other. FIG. 5A is a plan view of the light guide plate 10 and is a view seen from the normal direction of the light emitting surface 31 of the light guide plate 10. The dot pattern 41 shown in FIG. 5A is hexagonal in a plan view, and a plurality of dot patterns 41 are arranged adjacent to each other. Further, for example, as shown in FIG. 5B, a plurality of dot patterns 41 may be arranged. FIG. 5B is a plan view of the light guide plate 10 and is a view seen from the normal direction of the light emitting surface 31 of the light guide plate 10. The dot pattern 41 shown in FIG. 5B is circular in a plan view, and a plurality of dot patterns 41 are arranged adjacent to each other. The width of the dot patterns 41 to 43 is, for example, 30 μm, and the height of the dot patterns 41 to 43 is, for example, 5 to 6 μm, but the height is not limited to these values and may be other values. ..

The dot patterns 41 to 43 may have the same size (height and width), or may have different sizes. The dot pattern 41 and the dot pattern 42 may have the same size, and the dot patterns 41 and 42 and the dot pattern 43 may have different sizes. The dot pattern 41 and the dot pattern 43 may have the same size, and the dot patterns 41 and 43 and the dot pattern 42 may have different sizes. The dot pattern 42 and the dot pattern 43 may have the same size, and the dot pattern 41 and the dot patterns 42, 43 may have different sizes. The size of the dot patterns 41 to 43 may be changed according to the value of the thickness of the light guide plate 10 and the value of the pitch of the adjacent light source 11.

6A and 6B are cross-sectional views of the light guide plate 10. As shown in FIG. 6A, since the tapered surface 23 of the recess 20 extends from the bottom surface 21 toward the opening 22, the light emitted from the light source 11 in a direction other than the vertical direction of the light source 11. Corresponds to the tapered surface 23 of the recess 20. The light that hits the tapered surface 23 of the recess 20 and is incident on the light guide plate 10 is refracted toward the plane direction of the light guide plate 10. Therefore, the spread of the light incident on the light guide plate 10 is larger than the spread of the emitted light of the light source 11. Therefore, the light incident on the light guide plate 10 is greatly spread with respect to the light emitting surface 31 of the light guide plate 10, and the light is emitted from the light emitting surface 31 of the light guide plate 10 to the outside. As a result, the luminance distribution of the light emitting surface 31 of the light guide plate 10 is made uniform, and the luminance unevenness of the light guide plate 10 and the luminance unevenness of the liquid crystal display device can be suppressed.

As shown in FIG. 6A, the light in the light guide plate 10 hits the dot pattern 41 provided on the light emitting surface 31 of the light guide plate 10 and is refracted and scattered, and the light is emitted from the light emitting surface 31 of the light guide plate 10 to the outside. Is emitted. As a result, the luminance distribution of the light emitting surface 31 of the light guide plate 10 is made uniform. Further, as shown in FIG. 6A, the light in the light guide plate 10 travels inside the light guide plate 10 while being repeatedly reflected by the light emitting surface 31 and the opposite surface 32 of the light guide plate 10.

As shown in FIG. 6B, the light in the light guide plate 10 hits the dot pattern 42 provided on the opposite surface 32 of the light guide plate 10 and is refracted and scattered. The light in the light guide plate 10 is refracted and scattered, and the light is emitted from the light emitting surface 31 of the light guide plate 10 to the outside, so that the luminance distribution of the light emitting surface 31 of the light guide plate 10 is made uniform, and the light guide plate 10 It is possible to suppress uneven brightness and uneven brightness of the liquid crystal display device.

FIG. 7 is an enlarged cross-sectional view of the light guide plate 10. As shown in FIG. 7, the light emitted from the light source 11 in the vertical direction of the light source 11 hits the dot pattern 43 provided on the bottom surface 21 of the recess 20, is refracted and scattered, and is incident on the light guide plate 10. Light is emitted to the outside from the light emitting surface 31 of the light guide plate 10. Therefore, the luminance distribution of the portion directly above the light source 11 in the light emitting surface 31 of the light guide plate 10 is made uniform, and the luminance unevenness of the light guide plate 10 and the luminance unevenness of the liquid crystal display device can be suppressed.

The angle (tilt angle) of the tapered surface 23 of the recess 20 may be set according to the light distribution angle of the light source 11 and the angle (tilt angle) of the main axis (peak of the emitted light) of the light source 11. 8 (A) and 8 (B) are views showing the relationship between the angle of the main axis of the light source 11 and the angle of the tapered surface 23 of the recess 20. In FIGS. 8A and 8B, an example of the trajectory of the light emitted from the light source 11 is shown by a thick arrow. In FIG. 8A, the angle (θ1) of the main axis of the light source 11 with respect to the center line of the light source 11 is 50 degrees, and the angle (θ2) of the tapered surface 23 of the recess 20 with respect to the center line of the light source 11 is 60 degrees. be. In FIG. 8B, the angle (θ1) of the main axis of the light source 11 with respect to the center line of the light source 11 is 30 degrees, and the angle (θ2) of the tapered surface 23 of the recess 20 with respect to the center line of the light source 11 is 75 degrees. be.

The angle of the tapered surface 23 of the recess 20 is set according to the angle of the main axis of the light source 11 and the light distribution angle of the light source 11. As a result, even if the main axis of the light source 11 or the light distribution angle is changed by changing the type of the light source 11, the incident angle (θ3) of the light incident on the light emitting surface 31 of the light guide plate 10 is set to a constant angle. Can be maintained at. Further, by adjusting the angle of the tapered surface 23 of the recess 20, the peak direction of the emitted light of the light source 11 (the direction in which the intensity of the emitted light is maximized) can be controlled. Therefore, the luminance distribution of the light emitting surface 31 of the light guide plate 10 can be controlled for each type of the light source 11. Further, it is possible to control the luminance distribution of the entire light emitting surface 31 of the light guide plate 10 when a plurality of light sources 11 are arranged directly under the light guide plate 10.

FIG. 9 is a diagram showing the progress of light when light is emitted from the light source 11 within a range of about ± 20 degrees with respect to the angle of the main axis of the light source 11. As shown in FIG. 9, for light within a range of about ± 20 degrees with respect to the angle of the main axis of the light source 11, the light emitted from the light source 11 is the light guide plate in the same manner as the light traveling shown in FIG. Proceed inside 10.

By reducing the pitch of adjacent light sources and increasing the density of the light sources arranged directly under the light guide plate, uneven brightness of the light guide plate can be suppressed. On the other hand, when the pitch of adjacent light sources is large, the brightness unevenness of the light guide plate cannot be suppressed unless the thickness of the light guide plate is increased. According to the embodiment, the light source 11 is housed in the recess 20 of the light guide plate 10, and the emitted light of the light source 11 is refracted by the tapered surface 23 of the recess 20 to be incident on the light guide plate 10 so as to be inside the light guide plate 10. Increase the spread of light in. Further, according to the embodiment, the light hitting the dot patterns 41 to 43 provided on the light guide plate 10 is refracted and scattered. As a result, even when the pitch of the adjacent light source 11 is large, the brightness distribution of the light emitting surface 31 of the light guide plate 10 is made uniform without increasing the thickness of the light guide plate 10, and the brightness unevenness of the light guide plate 10 and the brightness of the light guide plate 10 are increased. It is possible to suppress uneven brightness of the liquid crystal display device. Therefore, it is possible to promote the thinning of the light guide plate 10 and suppress the uneven brightness of the light guide plate 10 and the uneven brightness of the liquid crystal display device.

The light source 11 may be embedded in the transparent resin layer. 10A to 10G are cross-sectional views of the light guide plate 10. In the structural example shown in FIG. 10A, the transparent resin layer 51 is arranged between the light guide plate 10 and the plurality of light sources 11 and the reflective layer 14. Therefore, a plurality of light sources 11 are embedded in the transparent resin layer 51. The light guide plate 10 is arranged on the transparent resin layer 51, and the light source 11 is not housed in the recess 20 of the light guide plate 10. The opposite surface 32 of the light guide plate 10 is in contact with the transparent resin layer 51, and the opposite surface 32 of the light guide plate 10 is not in contact with the reflective layer 14. The upper surface of the transparent resin layer 51 is flat. The upper surface of the transparent resin layer 51 is a contact surface with the light guide plate 10. The light emitted from the light source 11 passes through the transparent resin layer 51 and is incident on the light guide plate 10.

In the structural example shown in FIG. 10B, the transparent resin layer 52 is arranged between the light guide plate 10 and the plurality of light sources 11 and the reflective layer 14. Therefore, a plurality of light sources 11 are embedded in the transparent resin layer 52. The light guide plate 10 is arranged on the transparent resin layer 52, and the light source 11 is not housed in the recess 20 of the light guide plate 10. The opposite surface 32 of the light guide plate 10 is in contact with the transparent resin layer 52, and the opposite surface 32 of the light guide plate 10 is not in contact with the reflective layer 14. The upper surface of the transparent resin layer 52 is a flat surface. The upper surface of the transparent resin layer 52 is a contact surface with the light guide plate 10. The light emitted from the light source 11 passes through the transparent resin layer 52 and is incident on the light guide plate 10. In the structural example shown in FIG. 10B, the thickness of the transparent resin layer 52 is thinner than the thickness of the transparent resin layer 51 shown in FIG. 10A. Therefore, the transparent resin layer 52 directly above the light source 11 is thin.

In the structural example shown in FIG. 10C, the transparent resin layer 53 is arranged between the light guide plate 10 and the plurality of light sources 11 and the reflective layer 14. Therefore, a plurality of light sources 11 are embedded in the transparent resin layer 53. The light guide plate 10 is arranged on the transparent resin layer 53, and the light source 11 is not housed in the recess 20 of the light guide plate 10. The opposite surface 32 of the light guide plate 10 and the transparent resin layer 53 are in contact with each other, and the opposite surface 32 of the light guide plate 10 and the reflective layer 14 are not in contact with each other. A plurality of convex portions 61 are formed on the upper surface of the transparent resin layer 53. The upper surface of the transparent resin layer 53 is a contact surface with the light guide plate 10. FIG. 10C
The convex portion 61 of the transparent resin layer 53 shown in the above is substantially hemispherical, but the convex portion 61 of the transparent resin layer 53 is not limited to this shape, and the convex portion 61 of the transparent resin layer 53 is a protrusion having a cylindrical shape, a prismatic shape, a conical shape, a pyramidal shape, or the like. It may have a shape (convex shape). The convex portion 61 of the transparent resin layer 53 is located above the light source 11, and a part or all of the convex portion 61 of the transparent resin layer 53 is inserted in the concave portion 20 of the light guide plate 10. The bottom surface 21 of the concave portion 20 of the light guide plate 10 may be in contact with the convex portion 61 of the transparent resin layer 53, or the bottom surface 21 of the concave portion 20 of the light guide plate 10 and the convex portion 61 of the transparent resin layer 53 are not in contact with each other. May be. The tapered surface 23 of the concave portion 20 of the light guide plate 10 may be in contact with the convex portion 61 of the transparent resin layer 53, or the tapered surface 23 of the concave portion 20 of the light guide plate 10 and the convex portion 61 of the transparent resin layer 53 may be in contact with each other. It may be non-contact. The light emitted from the light source 11 passes through the transparent resin layer 53 and is incident on the light guide plate 10.

In the structural example shown in FIG. 10D, a plurality of transparent resin layers 54 are arranged below the light guide plate 10, and a transparent resin layer 54 is arranged between the light guide plate 10 and each of the plurality of light sources 11. Therefore, each light source 11 is embedded in each transparent resin layer 54. The light source 11 is not housed in the recess 20 of the light guide plate 10. The light guide plate 10 and the transparent resin layer 54 are in contact with each other, and the opposite surface 32 of the light guide plate 10 and the reflection layer 14 are not in contact with each other. The opposite surface 32 of the light guide plate 10 may be in contact with the transparent resin layer 54, or the opposite surface 32 of the light guide plate 10 may be in non-contact with the transparent resin layer 54. The transparent resin layer 54 shown in FIG. 10D has a substantially hemispherical shape, but is not limited to this shape. There may be. A part of the transparent resin layer 54 may enter the recess 20 of the light guide plate 10, or the transparent resin layer 54 may not enter the recess 20 of the light guide plate 10. The bottom surface 21 of the recess 20 of the light guide plate 10 may be in contact with the transparent resin layer 54, or the bottom surface 21 of the recess 20 of the light guide plate 10 and the transparent resin layer 54 may not be in contact with each other. The tapered surface 23 of the recess 20 of the light guide plate 10 may be in contact with the transparent resin layer 54, or the tapered surface 23 of the recess 20 of the light guide plate 10 may not be in contact with the transparent resin layer 54. The boundary portion between the tapered surface 23 of the recess 20 of the light guide plate 10 and the opposite surface 32 of the light guide plate 10 may be in contact with the transparent resin layer 54. The light emitted from the light source 11 passes through the transparent resin layer 54 and is incident on the light guide plate 10.

In the structural example shown in FIG. 10E, a plurality of transparent resin layers 55 are arranged below the light guide plate 10, and a transparent resin layer 55 is arranged between the light guide plate 10 and each of the plurality of light sources 11. Therefore, each light source 11 is embedded in each transparent resin layer 55. The light source 11 is not housed in the recess 20 of the light guide plate 10. The light guide plate 10 and the transparent resin layer 55 are in contact with each other, and the opposite surface 32 of the light guide plate 10 and the reflection layer 14 are not in contact with each other. The opposite surface 32 of the light guide plate 10 may be in contact with the transparent resin layer 55, or the opposite surface 32 of the light guide plate 10 may be in non-contact with the transparent resin layer 55. The transparent resin layer 55 has a shape in which two substantially hemispherical shapes are connected. A part of the transparent resin layer 55 may enter the recess 20 of the light guide plate 10, or the transparent resin layer 55 may not enter the recess 20 of the light guide plate 10. The bottom surface 21 of the recess 20 of the light guide plate 10 may be in contact with the transparent resin layer 55, or the bottom surface 21 of the recess 20 of the light guide plate 10 and the transparent resin layer 55 may be non-contact. The tapered surface 23 of the recess 20 of the light guide plate 10 may be in contact with the transparent resin layer 55, or the tapered surface 23 of the recess 20 of the light guide plate 10 and the transparent resin layer 55 may not be in contact with each other. The boundary portion between the tapered surface 23 of the recess 20 of the light guide plate 10 and the opposite surface 32 of the light guide plate 10 may be in contact with the transparent resin layer 55. The light emitted from the light source 11 passes through the transparent resin layer 55 and is incident on the light guide plate 10.

In the structural example shown in FIG. 10F, a plurality of transparent resin layers 56 are arranged below the light guide plate 10, and a transparent resin layer 56 is arranged between the light guide plate 10 and each of the plurality of light sources 11. Therefore, each light source 11 is embedded in each transparent resin layer 56. The light source 11 and the transparent resin layer 56 are housed in the recess 20 of the light guide plate 10. The opposite surface 32 of the light guide plate 10 and the reflective layer 14 are in contact with each other. That is, the light guide plate 10 and the reflective layer 14 are in close contact with each other. The bottom surface 21 of the recess 20 of the light guide plate 10 may be in contact with the transparent resin layer 56, or the recess 2 of the light guide plate 10 may be in contact with the bottom surface 21.
The bottom surface 21 of 0 and the transparent resin layer 56 may not be in contact with each other. The tapered surface 23 of the recess 20 of the light guide plate 10 may be in contact with the transparent resin layer 56, or the tapered surface 23 of the recess 20 of the light guide plate 10 may not be in contact with the transparent resin layer 56. The transparent resin layer 56 shown in FIG. 10F has a substantially hemispherical shape, but is not limited to this shape. There may be. The light emitted from the light source 11 passes through the transparent resin layer 56 and is incident on the light guide plate 10.

In the structural example shown in FIG. 10G, a plurality of transparent resin layers 57 are arranged below the light guide plate 10, and a transparent resin layer 57 is arranged between the light guide plate 10 and each of the plurality of light sources 11. Therefore, each light source 11 is embedded in each transparent resin layer 57. The light source 11 and the transparent resin layer 57 are housed in the recess 20 of the light guide plate 10. The opposite surface 32 of the light guide plate 10 and the reflective layer 14 are in contact with each other. That is, the light guide plate 10 and the reflective layer 14 are in close contact with each other. The bottom surface 21 of the recess 20 of the light guide plate 10 may be in contact with the transparent resin layer 57, or the bottom surface 21 of the recess 20 of the light guide plate 10 and the transparent resin layer 57 may not be in contact with each other. The tapered surface 23 of the recess 20 of the light guide plate 10 may be in contact with the transparent resin layer 57, or the tapered surface 23 of the recess 20 of the light guide plate 10 may not be in contact with the transparent resin layer 57. The transparent resin layer 57 has a shape in which two substantially hemispherical shapes are connected. The light emitted from the light source 11 passes through the transparent resin layer 57 and is incident on the light guide plate 10.

In the structural examples shown in FIGS. 10A to 10E, the light source 11 and the recess 20 of the light guide plate 10 overlap each other when viewed from the normal direction of the light emitting surface 31 of the light guide plate 10, and are below the recess 20 of the light guide plate 10. The light source 11 is arranged. By arranging any of the transparent resin layers 51 to 55 between the light guide plate 10 and the light source 11, the distance between the light guide plate 10 and the light source 11 is kept constant without increasing the thickness of the light guide plate 10. Can be kept. By separating the light source plate 10 and the light source 11 without accommodating the light source 11 in the recess 20 of the light guide plate 10, the spread of the light incident on the light guide plate 10 becomes large. The thickness of the transparent resin layers 51 to 55 is arbitrary. By changing the thickness of the transparent resin layers 51 to 55, the distance between the light guide plate 10 and the light source 11 can be changed. For example, by changing the thickness of the transparent resin layers 51 to 55 according to the type of the light source 11, the distance between the light guide plate 10 and the light source 11 can be set to the distance according to the type of the light source 11.

In the structural examples shown in FIGS. 10F and 10G, the light source 11 and the recess 20 of the light guide plate 10 overlap each other when viewed from the normal direction of the light emitting surface 31 of the light guide plate 10, and are below the recess 20 of the light guide plate 10. The light source 11 is arranged. By accommodating the light source 11 and the transparent resin layers 56 and 57 in the recess 20 of the light guide plate 10 and increasing the distance between the light source plate 10 and the light source 11, the spread of light incident on the light guide plate 10 can be increased. growing. The thicknesses of the transparent resin layers 56 and 57 are arbitrary. For example, the thicknesses of the transparent resin layers 56 and 57 may be changed according to the type of the light source 11.

The liquid crystal display device shown in the embodiment can be mounted on various electronic devices. Examples of electronic devices provided with such a liquid crystal display device include smartphones, digital cameras, tablet terminals, electronic books, wearable devices, car navigation devices, electronic dictionaries, electronic advertising boards, and the like. By using the light guide plate 10, the surface light source device 1, and the liquid crystal display device according to the embodiment, it is possible to reduce the size and thickness of the electronic device and suppress uneven brightness of the liquid crystal display device.

1 Surface light source device 2 Display panel 10 Light source plate 11 Light source 12 Frame 13 Mounting board 14 Reflective layer 15 Diffusion sheet 16 Prism sheet 17 Light-shielding member 20 Recess 21 Bottom surface 22 Opening 23 Tapered surface 31 Emission surface 32 Opposite surface 41 to 43 Dot pattern 51 ~ 57 Transparent resin layer

Claims (12)

A light guide plate having an light emitting surface that emits light, an opposite surface on the opposite side of the light emitting surface, a recess provided on the opposite surface, and a scattering portion provided on the light emitting surface that refracts and scatters light. When,
A light source arranged below the recess and
A reflective layer arranged on the opposite surface side of the light guide plate and around the light source,
A transparent resin layer arranged between the light guide plate and the light source,
Equipped with
A part of the reflective layer is arranged below the recess.
The other part of the reflective layer is in contact with the opposite surface.
The recess has a tapered surface that extends from the bottom surface of the recess toward the opening of the recess.
A surface light source device in which the tapered surface of the recess is in contact with the transparent resin layer. The surface light source device according to claim 1, wherein the scattering unit is a member separate from the light guide plate. The surface light source device according to claim 1 or 2, wherein the recess has a conical trapezoidal shape. The surface light source device according to any one of claims 1 to 3, wherein the scattering portion has a convex shape. The surface light source device according to any one of claims 1 to 4 , wherein the bottom surface of the recess and the transparent resin layer are in contact with each other. The surface light source device according to any one of claims 1 to 5 , wherein the reflective layer covers a part of a side surface of the light source. The surface light source device according to claim 6 , wherein the transparent resin layer covers the upper surface of the light source and the other part of the side surface of the light source. The surface light source device according to any one of claims 1 to 7 , wherein the angle of the tapered surface is set according to the angle of the main axis of the light source. The surface light source device according to any one of claims 1 to 8 , wherein the scattering unit is arranged above the light source. The plurality of recesses are provided on the opposite surface of the light guide plate.
Each of the plurality of light sources is arranged below the plurality of recesses.
Each of the plurality of scattering portions is arranged above the plurality of light sources, and the plurality of scattering portions are arranged above the plurality of light sources.
The reflective layer is arranged around the plurality of light sources, and the reflective layer is arranged around the plurality of light sources.
The surface light source device according to any one of claims 1 to 9 , wherein a part of the reflective layer is arranged below the plurality of recesses. The surface light source device according to any one of claims 1 to 10 .
A display panel that receives the light emitted from the surface light source device, and
Display device. An electronic device comprising the display device according to claim 11 .

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