JP2016170883A - Surface light source device and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface light source device which is for acquiring planar light efficiently with a simple structure even in the case where a plurality of pieces of single-color LEDs with high color purity are used, and a liquid crystal display device which is mounted with the surface light source device and which can display a high quality image.SOLUTION: A surface light source device includes: a plurality of kinds of light sources for emitting light of different colors; a plurality of light guide rods 6 for converting the light emitted by the plurality of kinds of light sources and entering from a light incident surface 61 into planar light; and a box-like reflection surface 7. The light guide rod 6 includes: a plurality of convex bodies 8 provided on the light incident surface 61; first concave parts 8a provided on the top surfaces of the plurality of convex bodies 8; a plurality of second concave parts 9; and a plurality of second prism structures 10. Each of the plurality of kinds of light sources is arranged inside the first concave part 8a. The second concave part 9 has a curve-shaped cross section symmetrical to the direction in which the light guide rod 6 extends with respect to the first concave part 8a.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a surface light source device and a liquid crystal display device.

  The liquid crystal display element included in the liquid crystal display device does not emit light by itself. For this reason, the liquid crystal display device includes a surface light source device on the back surface of the liquid crystal display element as a light source for illuminating the liquid crystal display element.

  In addition, the liquid crystal display element includes a color filter, and by transmitting only a part of the wavelength of light from the fluorescent lamp that emits white light in a continuous spectrum through the color filter, red, green, and blue light is transmitted. The display color is extracted to express the color. In this way, when only a part of the wavelength band light is cut out from the continuous spectrum light source to obtain the display color, the liquid crystal display element is designed to increase the color purity of the display color in order to widen the color reproduction range. Therefore, the transmission wavelength band of the color filter provided for must be set narrow. For this reason, when trying to increase the color purity of the display color, there arises a problem that the amount of light transmitted through the color filter is reduced and the luminance is lowered.

  In recent years, a liquid crystal display device using a monochromatic LED having a narrow wavelength width, that is, a high color purity as a light source has been proposed as an improvement measure for such problems. A backlight using a single color LED as a light emission source and covering up to white by additive color mixing has a wide color reproduction range, and can provide a high-quality image with high brightness.

  Realizing a high-quality surface light source device with high color reproduction characteristics, low brightness unevenness and color unevenness with as few light sources as possible and a simple structure, the workability at the time of production is good and the cost can be reduced. Technology development is desired.

  For example, in Patent Document 1, a white light source is made with a unit in which LEDs having R, G, and B colors are arranged close to each other, and the units are arranged in a matrix to reduce color unevenness. A technique for realizing a surface light source with a wide color reproduction range is disclosed.

JP 2011-205142 A

  However, when the technique of Patent Document 1 is used as a surface light source, LEDs having colors of R, G, and B are arranged close to each other, so that a range that can be irradiated by one unit of white light source is limited. Therefore, a large number of LED light sources are required. In Patent Document 1, a member that refracts the emitted light is attached to each of a large number of units. Thus, it leads to an increase in manufacturing procedures and manufacturing costs.

  The present invention has been made to solve the above-described problems. Even when a plurality of single color LEDs having high color purity are used, a surface light source for efficiently obtaining planar light with a simple configuration. An object of the present invention is to provide a liquid crystal display device that is equipped with the device and the surface light source device and can display a high-quality image.

  A surface light source device according to the present invention includes a plurality of types of light sources that emit light of different colors, a plurality of light guide rods that convert light emitted from a plurality of types of light sources incident from a light incident surface into planar light, and a plurality of light sources. A light source and a plurality of light guide rods arranged in parallel, and a box-like reflecting surface having an opening on the side from which planar light is emitted. The light guide rod is a surface along the direction in which the light rod extends, and the light guide rod includes a plurality of convex bodies provided on the light incident surface, a first concave portion provided on the top surface of the plurality of convex bodies, and a plurality of light guide bars. A first prism structure portion provided on at least one of the top surface or side surface of the convex body, and a plurality of second recess portions provided on the light exit surface facing the light incident surface so as to face the first recess portion A plurality of surfaces provided on two opposing surfaces in contact with the light incident surface and the light emitting surface and along the direction in which the light guide rod extends. Each of the plurality of types of light sources is disposed inside the first recess, and the second recess is a direction in which the light guide rod extends with respect to the first recess. Have a symmetrical cross section.

  By providing a plurality of convex bodies on the light incident surface of the light guide bar, providing a first concave portion on each convex body and arranging a light source on the inside thereof, light from the light source is efficiently introduced into the light guide bar. Can be guided. In addition, by providing the second concave portion 9 so as to face each first concave portion, it is possible to reflect the light beam incident on the light guide rod from the light incident surface toward the extending direction of the light guide rod. That is, the light from the light source can be used as propagating light that propagates while totally reflecting inside the light guide rod.

  Furthermore, by providing a plurality of second prism structures, it is possible to emit propagating light propagating while totally reflecting the inside of the light guide bar to the outside of the light guide bar. Further, by providing the first prism structure portion on at least one of the top surface or the side surface of the convex body, the light emitted from the side surface of the convex body 8 can be diffused over a wide range.

  From the above, the light guide bar can generate a rectangular uniform luminance distribution. Therefore, it is possible to obtain a surface light source device having a uniform luminance distribution by arranging a plurality of light guide bars capable of generating a uniform luminance distribution.

  Further, since light from the light source is propagated throughout the light guide rod, extended in the longitudinal direction, and extended in the short direction, it is possible to irradiate a wide area with a small number of light sources. As a result, a surface light source can be created with a small number of light guide rods, so that the number of backlight members can be reduced.

2 is a cross-sectional view of the liquid crystal display device according to Embodiment 1. FIG. 1 is a plan view of a surface light source device according to Embodiment 1. FIG. 2 is a perspective view of a light guide bar according to Embodiment 1. FIG. FIG. 3 is a partial cross-sectional view and a bottom view of the light guide bar according to Embodiment 1. FIG. 3 is a partial cross-sectional view and a bottom view of the light guide bar according to Embodiment 1. FIG. 3 is a partial cross-sectional view and a bottom view of the light guide bar according to Embodiment 1. 6 is a diagram illustrating light paths in the first and second recesses of the light guide rod according to Embodiment 1. FIG. It is a figure explaining the path | route of the light in the 1st recessed part and 2nd prism structure part of the light guide bar which concern on Embodiment 1. FIG. It is a figure explaining scattering of the light in the light guide bar which is not provided with the 1st prism structure part. 6 is a diagram for explaining light scattering in the first prism structure portion of the light guide rod according to Embodiment 1. FIG. 6 is a perspective view of a light guide bar according to Embodiment 2. FIG. 10 is a perspective view of a light guide bar according to Embodiment 3. FIG. 6 is a perspective view of a light guide bar according to Embodiment 4. FIG. 10 is a perspective view of a light guide bar according to Embodiment 5. FIG.

<Introduction>
In Japanese Patent Application No. 2014-167207 (filed on August 20, 2014) which is a prior application by the applicant of the present application, light from a light source is diffused by using a light guide rod and a reflecting bar containing a diffusing material, and is planar. Techniques for obtaining light are disclosed. Light from a plurality of light sources having a single color is incident on the light guide rod, and after it is actively emitted to the projection surface side, it is reflected from the bottom surface of the surface light source device by a reflection bar that exists directly above the light guide rod. By reflecting on the sheet, it is possible to spread light from the light source in the short direction of the light guide rod. Further, since light from any light source is reflected by the same plane of the reflection bar, color mixing can be performed in this process.

  By arranging such a light guide bar and a reflection bar, it is possible to realize a surface light source device in which light from a light source having a plurality of types of colors is mixed into a planar illumination light.

  However, in the surface light source device described in Japanese Patent Application No. 2014-167207 described above, a large amount of light traveling from the light guide rod toward the diffusion plate and toward the projection surface of the surface light source is reflected by the reflection bar. For this reason, the number of reflections of light in the surface light source device increases, and each time reflection occurs on the reflection bar or reflection sheet, a small amount of light is absorbed, resulting in a reduction in efficiency. As a result, an increase in the number of reflections due to the reflection bar and the reflection sheet results in a loss of light, leading to a decrease in luminance of the surface light source. For this reason, it is desirable to guide the light from the light source to the projection surface with as few reflections as possible. An embodiment of the present invention that solves the above problems will be described below.

<Embodiment 1>
FIG. 1 is a cross-sectional view schematically showing a configuration of an example of a liquid crystal display device 100 (including a surface light source device 500) according to the first embodiment. FIG. 2 is a plan view of the surface light source device 500. A cross section taken along line AB in FIG. 2 corresponds to FIG. In FIG. 2, descriptions other than the light guide rod 6 and the first and second light sources 4 and 5 are omitted for easy viewing. FIG. 3 is a perspective view of the light guide bar 6 in the first embodiment.

  As shown in FIG. 1, the liquid crystal display device 100 includes a transmissive liquid crystal panel 1, a first optical sheet 2, a second optical sheet 3, and a surface light source device 500. The surface light source device 500 irradiates the back surface 1 b of the liquid crystal panel 1 with light through the second optical sheet 3 and the first optical sheet 2.

  The surface light source device 500 includes a plurality of first light sources 4, a plurality of second light sources 5, a plurality of light guide bars 6, and a reflective surface 7. The first light source 4 is, for example, a blue LED. The second light source 5 emits light of a color different from that of the first light source 5. The second light source 5 is, for example, a green LED. The light guide rod 6 converts light emitted from the first and second light sources 4 and 5 incident from the light incident surface 61 into planar light.

  The reflecting surface 7 has a box shape. The box-shaped reflecting surface 7 accommodates a plurality of first and second light sources 4 and 5 and a plurality of light guide bars 6 arranged in parallel. In the reflection surface 7, the side where the planar light is emitted is opened.

  As shown in FIG. 1, the liquid crystal panel 1, the first optical sheet 2, the second optical sheet 3, and the surface light source device 500 are arranged in this order from the + z axis direction to the −z axis direction.

  The light guide rod 6 is a rod-shaped member made of a transparent resin (for example, acrylic, polycarbonate, etc.). The light guide bar 6 diffuses a part of the light from the first and second light sources 4 and 5 in all directions while propagating other light into the light guide bar 6 by total reflection of light, so that it is monochromatic. The light from a plurality of LEDs is mixed. The term “mixing” here means that the luminance distribution of the light beams from the respective light sources having different incident positions when reaching the back surface 1b of the liquid crystal panel 1 becomes uniform to some extent.

  The light guide bar 6 includes a plurality of convex bodies 8, a plurality of first concave portions 8a, a plurality of second concave portions 9, a plurality of first prism structure portions 11, and a plurality of second prism structures. Part 10.

  The light incident surface 61 of the light guide bar 6 is a surface along the direction in which the light guide bar 6 extends. The plurality of convex bodies 8 are provided on the light incident surface 61. A first concave portion 8 a is provided on the top surface of the convex body 8. The 1st light source 4 or the 2nd light source 5 is arrange | positioned inside the 1st recessed part 8a.

  By covering the first and second light sources 4 and 5 with the first concave portion 8a, it is possible to efficiently take the light emitted from the light source into the light guide rod 6. In addition, since the light taken into the light guide bar 6 repeats total reflection inside the light guide bar 6, the light from the first and second light sources 4 and 5 propagates to the end of the light guide bar 6. .

  4A and 4B are a partial cross-sectional view and a bottom view of the light guide bar 6, respectively. As shown in FIGS. 4A and 4B, the first recess 8a has a conical shape. The first recess 8a diffuses light from the light source in all directions. Moreover, as shown to Fig.5 (a), (b), the shape where the 1st recessed part 8a piled up the cone on the cylinder may be sufficient. Moreover, as shown to Fig.6 (a), (b), the shape where the 1st recessed part 8a piled up the cone on the square pillar may be sufficient.

  As shown in FIGS. 1 and 3, the plurality of second recesses 9 are provided on the light emitting surface 62 facing the light incident surface 61 so as to face the first recess 8 a. The second recess 9 has a curved cross section symmetrical to the longitudinal direction (x direction) of the light guide bar 6 with respect to the first recess 8a.

  FIG. 7 is a diagram illustrating light paths in the first and second recesses 8 a and 9 of the light guide rod 6. As shown in FIG. 7, by providing the first and second recesses 8a and 9, light rays 12 having a small divergence angle out of light rays emitted from the light source are reduced. The light beam 12 having a small divergence angle can be propagated into the light guide bar 6 with an equal amount of light from side to side.

  As shown in FIGS. 2 and 3, the plurality of second prism structures 10 are in contact with the light incident surface 61 and the light emitting surface 62, and extend in the direction (x direction) in which the light guide bar 6 extends. Further, they are provided on two opposing surfaces. The second prism structure 10 is provided to intentionally break the total reflection condition of the light beam taken into the light guide bar 6 and to emit the light beam to the outside of the light guide bar 6.

  The second prism structure unit 10 changes the angle of the light beam propagating through the light guide rod 6 by total reflection. That is, according to the arrangement and shape of the second prism structure portion 10, in the longitudinal direction (x direction) of the light guide rod 6, the amount of light emitted from the light guide rod 6 to the outside of the light guide rod 6, The light emission position can be controlled.

  FIG. 8 is a diagram for explaining a light path in the first concave portion 8 a and the second prism structure portion 10 of the light guide rod 6. As shown in FIG. 8, by providing the second prism structure unit 10, light from the light source can be actively emitted in the y direction. In other words, by providing the second prism structure portion 10, when irradiating light to the back surface 1 b of the liquid crystal panel 1, not only the x direction that is the longitudinal direction of the light guide bar 6 but also the y direction that is the short direction. Can also spread the light.

  As shown in FIG. 3, the second prism structure unit 10 is a triangular prism having a concave shape with respect to the side surface of the light guide bar 6. As shown in the enlarged view of FIG. 3, in the second prism structure unit 10, the angle θa formed by the surface 10a and the xz plane is in a range larger than 0 ° and smaller than 90 °. Further, the angle θb formed by the surface 10b and the xz plane is in a range larger than 0 ° and smaller than 90 °. The light propagating in the −x direction inside the light guide bar 6 is reflected by the surface 10 a of the second prism structure portion 10, so that a light beam is emitted to the outside of the light guide bar 6. Similarly, light propagating in the + x direction inside the light guide bar 6 is reflected by the surface 10 b of the second prism structure 10, so that a light beam is emitted to the outside of the light guide bar 6.

  As shown in FIG. 3, the first prism structure portion 11 is provided in each of the plurality of convex bodies 8. The first prism structure portion 11 is provided on two opposite side surfaces of the convex body 8 on the ± y direction side. The first prism structure 11 is a triangular prism repeating structure extending in the x direction. As shown in the enlarged view of FIG. 3, in each triangular prism constituting the first prism structure portion 11, the angle θa formed by the surface 11a surface and the xz plane is in a range larger than 0 ° and smaller than 90 °. . Further, the angle θb formed by the surface 11b and the xz plane is in a range larger than 0 ° and smaller than 90 °.

  FIG. 9 is a diagram illustrating a light path when the light guide bar 6 does not include the first prism structure portion 11 on the side surface of the convex body 8. FIG. 10 is a diagram illustrating a light path when the light guide bar 6 includes the first prism structure portion 11 on the side surface of the convex body 8. In FIG. 9, when the light beam 13 diffuses out of the light guide rod 6, it is refracted by the flat side surface of the convex body 8 and is emitted toward the z direction side. On the other hand, in FIG. 10, the light beam 13 is emitted toward the ± y direction side at the first prism structure portion 11 provided on the side surface of the light guide rod 6 with a larger refraction angle when emitted. That is, by providing the first prism structure unit 11, it is possible to spread light emitted from the light source in the y direction and make the luminance on the projection surface more uniform.

  The second prism structure 10 may be provided also on the light incident surface 61 of the light guide bar 6. Further, a plurality of the second prism structure portions 10 may be arranged continuously. Further, the second prism structure 10 does not need to penetrate the side surface of the light guide bar 6.

  Further, the convex body 8, which is a structure for allowing the light of the first and second light sources 4 and 5 to enter the light guide rod 6, is disposed at any position on the light incident surface 61 of the light guide rod 6. Also good.

  Further, the second prism structure 10 may have a convex structure with respect to the light guide bar 6. Furthermore, the shape of the second prism structure 10 may be not only a triangular prism but also a quadrangular pyramid.

  Further, in the first embodiment, the first prism structure portion 11 is provided on two opposing side surfaces facing in the ± y direction among the side surfaces of the convex body 8. Furthermore, the first prism structure 11 may be provided on two opposing side surfaces facing in the ± x direction among the side surfaces of the convex body 8. Further, the shape of the first prism structure portion 11 may be not only a triangular prism but also a shape in which square pyramids are arranged.

  Further, the size of the triangular prism structure in the first and second prism structures 11 and 10 can be arbitrarily changed. The size and angles θa and θb may be different for each triangular prism.

  In the first embodiment, the first and second light sources 4 and 5 are LEDs. For example, the first light source 4 is an LED and the second light source 5 is a laser diode. Light sources with different characteristics may be used.

  Two or more types (two colors) of light sources for one light guide rod 6 may be installed. The number of light sources for one light guide bar 6 may be two or three or more.

  The number of the plurality of light guide bars 6 arranged in the surface light source device 500 can be changed according to the required luminance and the size of the surface light source.

<Effect>
The surface light source device 500 according to the first embodiment includes a plurality of types of light sources (first and second light sources 4 and 5) that emit light of different colors and a light emitted from a plurality of types of light sources that are incident from the light incident surface 61. A plurality of light guide rods 6 that convert light into planar light, a plurality of types of light sources and a plurality of light guide rods 6 arranged in parallel, and a box-like shape in which the side from which planar light is emitted is opened The light incident surface 61 of the light guide bar 6 is a surface along the direction (x direction) in which the light guide bar 6 extends, and the light guide bar 6 has a light incident surface 61. The plurality of convex bodies 8 provided on the top surface, the first concave portion 8a provided on the top surfaces of the plurality of convex bodies 8, and the first surface provided on at least one of the top surfaces or side surfaces of the plurality of convex bodies 8 A plurality of second recesses provided on the prism structure 11 and the light exit surface 62 facing the light incident surface 61 so as to face the first recess 8a. 9 and a plurality of second prism structures 10 provided on two opposing surfaces in contact with the light incident surface 61 and the light emitting surface 62 and along the direction in which the light guide rod 6 extends. Each of the plurality of types of light sources is disposed inside the first recess 8a, and the second recess 9 is in a direction (x direction) in which the light guide bar 6 extends with respect to the first recess 8a. It has a symmetrical curved cross section.

  Therefore, by providing a plurality of convex bodies 8 on the light incident surface 61 of the light guide bar 6 and providing the first concave portions 8a on each convex body 8 and arranging the light source on the inside thereof, the light from the light source can be obtained. The light can be efficiently guided into the light guide bar 6. Further, by providing a second recess 9 having a curved cross section symmetrical to the direction (x direction) in which the light guide rod 6 extends with respect to the first recess 8a, the light is guided from the light incident surface 61. The light incident on the bar 6 can be reflected toward the extending direction of the light guide bar 6. That is, the light from the light source can be used as propagating light that propagates while totally reflecting inside the light guide rod 6.

  Further, by providing the plurality of second prism structure portions 10, it is possible to emit propagating light propagating while totally reflecting the inside of the light guide bar 6 to the outside of the light guide bar 6. Further, by providing the first prism structure 11 on the side surface of the convex body 8, the light emitted from the side surface of the convex body 8 can be diffused over a wide range.

  As described above, in the first embodiment, each light guide bar 6 can generate a rectangular uniform luminance distribution. Therefore, it is possible to obtain a surface light source device having a uniform luminance distribution by arranging a plurality of light guide bars 6 capable of generating a uniform luminance distribution. Further, regardless of the position of the first and second light sources 4 and 5 on the light incident surface 61, each light source can be adjusted by adjusting the shape and arrangement of the first and second prism structures 11 and 10. Since it is possible to distribute the luminance distribution at the time of emission of the light guide rod 6 by the light from the substantially equal distribution, color unevenness hardly occurs. In addition, since each light source is monochromatic, the color reproduction range can be kept wide.

  Further, since light from the light source is propagated throughout the light guide rod, extended in the longitudinal direction, and extended in the short direction, it is possible to irradiate a wide area with a small number of light sources. As a result, it is possible to create a surface light source with a small number of light guide rods 6, and thus the number of backlight members can be reduced.

  In the surface light source device 500 according to the first embodiment, the first recess 8a has a shape including a cone.

  Therefore, the light from the light source can be diffused in all directions by making the first recess 8a conical.

  Further, in the surface light source device 500 according to the first embodiment, the second prism structure unit 10 is a triangular prism.

  Therefore, it is possible to adjust the angle of the light beam emitted from the light guide bar 6 by changing the angle of the surfaces constituting the triangular prism.

  In the surface light source device 500 according to the first embodiment, the second prism structure unit 10 may be a quadrangular pyramid.

  Therefore, it is possible to adjust the angle of the light beam emitted from the light guide bar 6 by changing the shape of the quadrangular pyramid.

  In the surface light source device 500 according to the first embodiment, the second prism structure unit 10 has a concave shape.

  Therefore, by making the second prism structure portion 10 concave with respect to the light guide bar 6, light rays propagating through the light guide bar 6 can be efficiently reflected.

  In the surface light source device 500 according to the first embodiment, the second prism structure unit 10 may have a convex shape.

  Therefore, even if the second prism structure portion 10 has a convex shape with respect to the light guide rod 6, the light beam propagating through the light guide rod 6 can be reflected.

  Further, in the surface light source device 500 according to the first embodiment, the second prism structure unit 10 may be provided also on the light incident surface 61 of the light guide bar 6.

  Therefore, by providing the second prism structure portion 10 also on the light incident surface 61 of the light guide bar 6, the propagating light propagating while totally reflecting the inside of the light guide bar 6 is transmitted to the outside of the light guide bar 6. It can be injected efficiently.

  In the surface light source device 500 according to the first embodiment, the first prism structure portion 11 is provided on two side surfaces facing each other among the side surfaces of the convex body 8.

  Therefore, for example, by providing the first prism structure 11 on two side surfaces orthogonal to the extending direction of the light guide bar 6, not only the direction in which the light guide bar 6 extends but also the width of the light guide bar 6. It is possible to diffuse light also in the direction.

  In the surface light source device 500 according to the first embodiment, the first prism structure unit 11 may be provided on all surfaces of the side surfaces of the convex body 8.

  Therefore, by providing the first prism structure 11 on all side surfaces of the convex body 8, the light emitted from the light source can be diffused in a wider range.

  In the surface light source device 500 according to the first embodiment, the first prism structure unit 11 includes a plurality of triangular prisms extending in the direction in which the light guide bar 6 extends.

  Therefore, it is possible to adjust the angle of the light beam emitted from the side surface of the convex body 8 by changing the angle of the surface constituting each triangular prism.

  Further, in the surface light source device 500 according to the first embodiment, the first prism structure unit 11 may include a plurality of quadrangular pyramids.

  Therefore, the same effect can be obtained even when a plurality of quadrangular pyramids are provided instead of the triangular prism.

  In the surface light source device 500 according to the first embodiment, the plurality of types of light sources (that is, the first and second light sources 4 and 5) are LEDs.

  Therefore, by using the first and second light sources 4 and 5 as monochromatic LED light sources, when the surface light source device is used as the backlight of the liquid crystal display device, the color reproduction range of the liquid crystal display device can be kept wide. .

  In the surface light source device 500 according to the first embodiment, at least one type of light source of the plurality of types of light sources is a laser diode.

  Therefore, even when a laser diode having high straightness is used as the light source, the light guide bar 6 in the first embodiment can realize a planar light source with uniform luminance.

  The liquid crystal display device 100 according to the first embodiment includes the surface light source device 500 and the liquid crystal panel 1 that displays an image using light emitted from the surface light source device.

  Therefore, according to the first embodiment, the configuration of the surface light source device 500 can be simplified without degrading the display quality of the liquid crystal display device 100.

<Embodiment 2>
FIG. 11 is a perspective view of the light guide bar 6A in the second embodiment. The light guide bar 6A according to the second embodiment includes a first prism structure part 11A instead of the first prism structure part 11 of the light guide bar 6 according to the first embodiment. The configuration other than the first prism structure portion 11A in the second embodiment is the same as that in the first embodiment.

  In Embodiment 1, the 1st prism structure part 11 was the repeating structure of the triangular prism extended in the direction (x direction) where the light-guide rod 6 extends. On the other hand, in the second embodiment. The first prism structure 11 </ b> A is a repeating structure of triangular prisms extending in the direction perpendicular to the light incident surface 61 (z direction).

  As shown in FIG. 11, the first prism structure portion 11 </ b> A is provided on two side surfaces of the convex body 8 facing in the ± y direction. The first prism structure portion 11A is a triangular prism repeating structure extending in the z direction. As shown in the enlarged view of FIG. 11, in each triangular prism constituting the first prism structure portion 11A, the angle θa formed by the surface 11Aa and the xz plane is in a range larger than 0 ° and smaller than 90 °. . Further, the angle θb formed by the surface 11Ab and the xz plane is in a range larger than 0 ° and smaller than 90 °.

  As in the first embodiment, in order to reduce color unevenness and luminance unevenness in the planar light of the surface light source device 500, the light from the light source is taken into the light guide rod 6 as much as possible and propagated. It is preferable to emit the light from the light source to the outside of the light guide bar 6 so that the luminance distribution of light is as uniform as possible. However, there is also light that reaches the projection surface as direct light without being taken into the light guide rod 6. Such light also needs to be controlled so as to have a non-biased luminance distribution depending on the position of the light source.

  In the second embodiment, by providing the first prism structure portion 11A, the divergence angle of the light emitted from the xz plane in the convex body 8 of the light guide rod 6A is increased, and the light is diffused further away. Therefore, there is an effect of suppressing luminance unevenness on the projection surface.

  Further, the first prism structure 11A may be provided not only on the side surface on the ± y direction side of the convex body 8 but also on the side surface on the ± x direction side. Furthermore, the shape of the first prism structure portion 11A is not limited to a triangular prism shape, and may be a repeating quadrangular pyramid.

  In addition, the size of the triangular prism structure in the first prism structure portion 11A can be arbitrarily changed, and the size and angle of each triangular prism may be different.

<Effect>
In the surface light source device 500 according to the second embodiment, the first prism structure portion 11 </ b> A includes a plurality of triangular prisms extending in a direction perpendicular to the light incident surface 61.

  Therefore, in the second embodiment, the first prism structure portion 11A is provided on the side surface of the convex body 8 of the light guide bar 6A, thereby increasing the divergence angle of light emitted from the side surface. Therefore, there is an effect of suppressing luminance unevenness on the projection surface. That is, the light guide bar 6A can generate a rectangular uniform luminance distribution. The surface light source device 500 in which a plurality of light guide bars 6A capable of generating a uniform luminance distribution is arranged can be handled as a surface light source having a uniform luminance distribution. Further, regardless of the position of the light source, the luminance distribution of light from each light source emitted from the light guide rod 6A can be adjusted by adjusting the shape and arrangement of the first and second prism structures 11A and 10. Almost equal distribution is possible. Therefore, it is possible to obtain planar light with suppressed color unevenness.

<Embodiment 3>
FIG. 12 is a perspective view of the light guide bar 6B according to the third embodiment. The light guide bar 6B according to the second embodiment includes a first prism structure part 11B instead of the first prism structure part 11 of the light guide bar 6 according to the first embodiment. The configuration other than the first prism structure portion 11B in the second embodiment is the same as that in the first embodiment.

  The first prism structure portion 11B is provided on the top surface of the convex body 8 (that is, the surface facing the −z direction side of the convex body 8). The first prism structure portion 11B includes a plurality of triangular prisms extending in the x direction. As shown in the enlarged view in FIG. 12, in each triangular prism constituting the first prism structure portion 11B, the angle θa formed by the surface 11Ba surface with the xy plane is in a range larger than 0 ° and smaller than 90 °. . Further, the angle θb formed by the surface 11Bb and the xy plane is in a range larger than 0 ° and smaller than 90 °.

  As in the first embodiment, in order to reduce color unevenness and luminance unevenness in the planar light of the surface light source device, the light from the light source is taken into the light guide bar 6 as much as possible and propagated, and each light source It is preferable to emit the light from the light guide bar 6B so that the luminance distribution of the light from the light source becomes as uniform as possible. Furthermore, the light taken into the light guide bar 6B and propagating to the top surface of the convex body 8 is likely to be emitted in the vicinity of the convex body 8 and easily causes luminance unevenness.

  Therefore, in the third embodiment, the first prism structure portion 11B is provided on the top surface of the convex body 8. By providing the first prism structure portion 11B, the light beam that is incident on the top surface of the convex body 8 and is totally reflected and propagates into the light guide rod 6 or the top surface of the convex body 8 is transmitted. It is possible to control the direction in the yz plane of the light beam that is reflected by the reflecting surface 7 and then emitted to the outside of the light guide bar 6B.

  That is, the divergence angle of the light emitted from the xz plane or the yz plane after being reflected on the top surface of the convex body 8 of the light guide bar 6B is increased, and the light can be diffused further, and the luminance distribution is increased. Since it is not biased, there is an effect of suppressing unevenness in luminance on the projection surface due to high intensity direct light.

  Further, the shape of the first prism structure portion 11B is not limited to a triangular prism shape, and may be a repeating quadrangular pyramid. In addition, the size of the triangular prism structure in the first prism structure portion 11B can be arbitrarily changed, and the size and angle of each triangular prism may be different.

<Effect>
In the surface light source device 500 according to the third embodiment, the first prism structure portion 11B is provided on the top surface of the convex body 8.

  Therefore, by providing the first prism structure portion 11B on the top surface of the convex body 8, the divergence angle of the light emitted from the side surface of the convex body 8 is increased after reflection on the top surface of the convex body 8. . Therefore, there is an effect of suppressing luminance unevenness on the projection surface. That is, the light guide bar 6B can generate a rectangular uniform luminance distribution. The surface light source device 500 in which a plurality of light guide bars 6B capable of generating a uniform luminance distribution is arranged can be handled as a surface light source having a uniform luminance distribution. Further, regardless of the position of the light source, the luminance distribution of light from each light source emitted from the light guide bar 6B can be adjusted by adjusting the shape and arrangement of the first and second prism structures 11B and 10. Almost equal distribution is possible. Therefore, it is possible to obtain planar light with suppressed color unevenness.

  In the surface light source device 500 according to the third embodiment, the first prism structure portion 11B includes a plurality of triangular prisms extending in the direction in which the light guide bar 6B extends.

  Therefore, it is possible to adjust the angle of the light beam emitted from the light guide bar 6B by changing the angle of the surfaces constituting each triangular prism.

<Embodiment 4>
FIG. 13 is a perspective view of the light guide bar 6C according to the fourth embodiment. The light guide rod 6C according to the fourth embodiment further includes a first prism structure portion 11C instead of the first prism structure portion 11 of the light guide rod 6 according to the first embodiment. In the fourth embodiment, the configuration other than the first prism structure portion 11C is the same as that of the first embodiment.

  In the fourth embodiment, the first prism structure portion 11C is provided on the top surface of the convex body 8. The first prism structure portion 11C is a triangular prism repeating structure extending in the y direction. As shown in the enlarged view of FIG. 12, in each triangular prism constituting the first prism structure portion 11C, the angle θa formed by the surface 11Ca surface with the xy plane is in a range larger than 0 ° and smaller than 90 °. . Further, the angle θb formed by the surface 11Cb and the xy plane is in a range larger than 0 ° and smaller than 90 °.

  As in the first embodiment, in order to reduce color unevenness and luminance unevenness in the planar light of the surface light source device, the light from the light source is taken into the light guide bar 6 as much as possible and propagated, and each light source It is preferable to emit the light from the light guide bar 6 so that the luminance distribution of the light from the light source is as uniform as possible. Furthermore, the light taken into the light guide rod 6C and propagating to the top surface of the convex body 8 is likely to be emitted in the vicinity of the convex body 8 and easily causes luminance unevenness.

  Therefore, in the fourth embodiment, the first prism structure portion 11C is provided on the top surface of the convex body 8. By providing the first prism structure portion 11C, the light beam is incident on the top surface of the convex body 8, and is totally reflected and propagates inside the light guide rod 6C, or is transmitted through the top surface of the convex body 8. It is possible to control the direction in the yz plane of the light beam that is reflected by the reflecting surface 7 and then emitted to the outside of the light guide rod 6C.

  That is, after the light is reflected from the top surface of the convex body 8 of the light guide rod 6C, the divergence angle of light emitted from the side surface on the ± y direction side or the side surface on the ± x direction side is increased, and the light is diffused further away. In addition, since the luminance distribution is not biased, there is an effect of suppressing luminance unevenness on the projection surface due to high intensity direct light.

  Further, the shape of the first prism structure portion 11C is not limited to a triangular prism shape, and may be a repeating quadrangular pyramid. In addition, the size of the triangular prism structure in the first prism structure portion 11C can be arbitrarily changed, and the size and angle of each triangular prism may be different.

<Effect>
In the surface light source device 500 according to the fourth embodiment, the first prism structure portion 11C is provided on the top surface of the convex body 8.

  Accordingly, by providing the first prism structure portion 11C on the top surface of the convex body 8, after reflecting on the top surface of the convex body 8, the side surface on the ± y direction side or the ± x direction side of the convex body 8 The divergence angle of the light emitted from the side surface increases. Therefore, there is an effect of suppressing luminance unevenness on the projection surface. That is, the light guide bar 6C can generate a rectangular uniform luminance distribution. The surface light source device 500 in which a plurality of light guide bars 6C capable of generating a uniform luminance distribution is arranged can be handled as a surface light source having a uniform luminance distribution. Further, regardless of the position of the light source, the luminance distribution of light from each light source emitted from the light guide rod 6C can be adjusted by adjusting the shape and arrangement of the first and second prism structures 11C and 10. Almost equal distribution is possible. Therefore, it is possible to obtain planar light with suppressed color unevenness.

  In the surface light source device 500 according to the fourth embodiment, the first prism structure portion 11C includes a plurality of triangular prisms extending in a direction orthogonal to the direction in which the light guide bar 6C extends.

  Therefore, it is possible to adjust the angle of the light beam emitted from the light guide rod 6C by changing the angle of the surfaces constituting each triangular prism.

<Embodiment 5>
FIG. 14 is a perspective view of the light guide bar 6D according to the fifth embodiment. The light guide rod 6D according to the fifth embodiment includes a first prism structure portion 11D instead of the first prism structure portion 11 of the light guide rod 6 according to the first embodiment. In the fifth embodiment, the configuration other than the first prism structure portion 11B is the same as that of the first embodiment.

  The first prism structure portion 11D is provided on two opposing side surfaces of the convex body 8 facing in the ± y direction. The first prism structure portion 11D includes first and second regions 11Da and 11Db. The first region 11Da is composed of a plurality of triangular prisms extending in the extending direction (x direction) of the light guide rod 6D. The second region 11Db is composed of a plurality of triangular prisms extending in a direction (z direction) perpendicular to the light incident surface 61 of the light guide rod 6D. The second region 11Db is sandwiched between the two first regions 11Da.

  As in the first embodiment, in order to reduce color unevenness and luminance unevenness in the surface light source device 500, since the light emitted from the first and second light sources 4 and 5 is monochromatic, it is guided as much as possible. It is preferable that the light beam is taken into the light rod and propagated, and is emitted to the outside of the light guide rod so that the luminance distribution of light from each light source becomes as uniform as possible. For light that reaches the projection surface as direct light without being taken into the light guide rod, it is necessary to control the luminance distribution so as not to be biased depending on the position of the light source.

  By providing the first prism structure portion 11D including the first and second regions 11Da and 11Db on the side surface of the convex body 8, yz of the light beam emitted from the side surface of the convex body 8 to the outside of the light guide rod 6D. The direction in the plane can be controlled. Moreover, the direction in the xy plane of the light ray inject | emitted from the side surface of the convex body 8 to the exterior of the light guide rod 6D can also be controlled.

  Therefore, the divergence angle of the light emitted from the side surface of the convex body 8 after being reflected at the top surface of the convex body 8 is increased, and the light can be diffused further. Since the luminance distribution of divergent light is not biased, there is an effect of suppressing luminance unevenness on the projection surface due to high intensity direct light.

  Further, the first prism structure portion 11D may be provided not only on the side surface on the ± y direction side of the convex body 8 but also on the side surface on the ± x direction side. Furthermore, the first prism structure portion 11 </ b> D may be provided on the top surface of the convex body 8. In this case, the first prism structure portion 11D is provided avoiding the opening of the first recess 8a.

  Furthermore, the shape of the first prism structure portion 11D is not limited to a triangular prism shape, and may be a repeating quadrangular pyramid.

  In addition, the size of the triangular prism structure in the first prism structure portion 11D can be arbitrarily changed, and the size and angle of each triangular prism may be different.

  Further, in the first prism structure portion 11D, the ratio of the areas of the first region 11Da and the second region 11Db can be arbitrarily changed according to the intended luminance distribution.

<Effect>
In the surface light source device 500 according to the fifth embodiment, the first prism structure unit 11D includes a plurality of triangular prisms having different extending directions.

  Therefore, by providing a plurality of triangular prisms having different extending directions in the same surface on the side surface of the convex body 8, it is possible to reduce the deviation in the divergence direction of light passing through the side surface. Therefore, there is an effect of suppressing luminance unevenness on the projection surface. That is, the light guide bar 6D can generate a rectangular uniform luminance distribution. The surface light source device 500 in which a plurality of light guide bars 6A capable of generating a uniform luminance distribution is arranged can be handled as a surface light source having a uniform luminance distribution. Further, regardless of the position of the light source, the luminance distribution of light from each light source emitted from the light guide rod 6A can be adjusted by adjusting the shape and arrangement of the first and second prism structure portions 11D and 10. Almost equal distribution is possible. Therefore, it is possible to obtain planar light with suppressed color unevenness.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

  DESCRIPTION OF SYMBOLS 1 Liquid crystal panel, 1a Image | video display surface, 1b back surface, 2nd 1st optical sheet, 2nd optical sheet, 4th 1st light source, 5th 2nd light source, 6, 6A, 6B, 6C, 6D , 61 Light incident surface, 62 Light exit surface, 7 Reflecting surface, 8 Convex body, 8a First concave portion, 9 Second concave portion, 10 Second prism structure portion, 11, 11A, 11B, 11C First Prism structure part, 12, 13 rays, 100 liquid crystal display device, 500 surface light source device.

Claims (18)

Multiple types of light sources that emit light of different colors,
A plurality of light guide rods that convert light emitted from the plurality of types of light sources incident from the light incident surface into planar light;
A plurality of light sources and a plurality of light guide rods arranged in parallel; and a box-shaped reflecting surface in which a side from which the planar light is emitted is opened;
With
The light incident surface of the light guide bar is a surface along a direction in which the light guide bar extends,
The light guide rod is
A plurality of convex bodies provided on the light incident surface;
A first recess provided on a top surface of the plurality of convex bodies;
A first prism structure portion provided on at least one of a top surface or a side surface of the plurality of convex bodies;
A plurality of second recesses provided on the light exit surface facing the light incident surface so as to face the first recess;
A plurality of second prism structures provided on two opposing surfaces in contact with the light incident surface and the light emitting surface and along a direction in which the light guide rod extends;
With
Each of the plurality of types of light sources is disposed inside the first recess,
The second recess has a curved cross section symmetrical to the direction in which the light guide rod extends with respect to the first recess.
Surface light source device. The first recess has a shape including a cone.
The surface light source device according to claim 1. The second prism structure is a triangular prism;
The surface light source device according to claim 1. The second prism structure is a quadrangular pyramid.
The surface light source device according to claim 1. The second prism structure is concave.
The surface light source device according to any one of claims 1 to 4. The second prism structure is convex.
The surface light source device according to any one of claims 1 to 4. The second prism structure portion is also provided on the light incident surface of the light guide rod.
The surface light source device according to any one of claims 1 to 6. The first prism structure portion is provided on two side surfaces facing each other among the side surfaces of the convex body.
The surface light source device according to any one of claims 1 to 7. The first prism structure portion is provided on all of the side surfaces of the convex body.
The surface light source device according to any one of claims 1 to 7. The first prism structure portion is provided on the top surface of the convex body.
The surface light source device according to any one of claims 1 to 7. The first prism structure portion includes a plurality of triangular prisms extending in a direction in which the light guide rod extends.
The surface light source device according to any one of claims 8 to 10. The first prism structure portion includes a plurality of triangular prisms extending in a direction perpendicular to the incident surface.
The surface light source device according to claim 8 or 9. The first prism structure portion includes a plurality of triangular prisms extending in a direction orthogonal to a direction in which the light guide rod extends.
The surface light source device according to claim 10. The first prism structure portion includes a plurality of triangular prisms having different extending directions.
The surface light source device according to any one of claims 8 to 10. The first prism structure includes a plurality of quadrangular pyramids;
The surface light source device according to any one of claims 8 to 10. The plurality of types of light sources are LEDs.
The surface light source device according to any one of claims 1 to 15. At least one of the plurality of types of light sources is a laser diode;
The surface light source device according to any one of claims 1 to 15. A surface light source device according to any one of claims 1 to 17,
A liquid crystal panel for displaying an image using light irradiated by the surface light source device;
Comprising
Liquid crystal display device.

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