JP2009004216A - Planar light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planar light source device capable of uniforming a luminance distribution. <P>SOLUTION: This planar light source device A which emits planar light is structured, such that a plurality of columnar parts 2A, each of which extends in direction x and arranged in direction y, and a plurality of columnar parts 2B each extending in the direction y and arranged in the direction x are connected at the mutual intersecting points; and each of the columnar parts 2A and 2B is provided with a light guide member 1, having an entering surface formed at least on one end side, a reflecting part, and an emitting surface formed on the side opposite to the reflecting part, and a plurality of LED units 6 facing the incident surfaces of the plurality of columnar parts 2A and 2B. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a planar light source device used as a backlight of a liquid crystal display device, for example.

  FIG. 4 shows an example of a conventional planar light source device (see, for example, Patent Document 1). A planar light source device X shown in the figure is used as a backlight of a liquid crystal display device Y, and includes a plurality of cold cathode tubes 91. The cold cathode tube 91 has a shape extending in one direction and is configured to emit linear light. The plurality of cold cathode tubes 91 are arranged in parallel to each other. The plurality of linear lights emitted from the plurality of cold cathode tubes 91 are emitted as planar light by passing through, for example, a diffusion filter (not shown). The planar light passes through the liquid crystal panel 92 of the liquid crystal display device Y, whereby a desired image or video is displayed.

  However, the planar light source device X forms planar light using a plurality of linear lights. These linear lights extend along a certain direction. For this reason, the luminance distribution of the planar light from the planar light source device X tends to be a plurality of stripes extending in the certain direction. In such a case, there is a problem that unevenness occurs in the image of the liquid crystal display device Y.

JP 2007-123030 A

  The present invention has been conceived under the above-described circumstances, and an object thereof is to provide a planar light source device capable of achieving uniform luminance distribution.

  The planar light source device provided by the present invention provides planar light that spreads in the first and second directions that are perpendicular to each other, and the third planar light that is perpendicular to both the first and second directions. A planar light source device that emits in a direction, each extending in the first direction, and a plurality of first columnar portions arranged in the second direction, each in the second direction The plurality of second columnar portions extending in the first direction are connected to each other at intersections, and each of the first and second columnar portions includes An incident surface provided on at least one end side, a reflecting portion provided on one side in the third direction, and an emission surface provided on the other side in the third direction are formed. The light guide member and the incident surfaces of the plurality of first and second columnar portions are directly opposed to each other. It is characterized and a plurality of light sources, in that it comprises that.

  According to such a configuration, light is emitted from the plurality of first and second columnar portions orthogonal to each other. For example, when planar light is configured by transmitting such light through a diffusion filter, it is possible to prevent the luminance distribution of the planar light from becoming a plurality of stripes extending in one direction. Therefore, it is possible to make the luminance distribution of the planar light from the planar light source device uniform, and for example, to uniformly display an image of a liquid crystal display device in which the planar light source device is used as a backlight. it can.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

  1 to 3 show an example of a planar light source device according to the present invention. The planar light source device A of the present embodiment includes a light guide member 1 and a plurality of LED units 6, and transmits light emitted from the light guide member 1 through a diffusion filter (not shown), for example. It is configured to be able to emit planar light extending in x and y in the direction z. The planar light source device A is used as a backlight of a liquid crystal display device, for example.

  The light guide member 1 is made of a transparent resin such as PMMA or polycarbonate, for example, and has a plurality of columnar portions 2A and 2B. The plurality of columnar portions 2A and 2B are columnar shapes having, for example, a rectangular cross section. Each of the plurality of columnar portions 2A extends in the direction x, and is arranged at equal intervals in the direction y. Each of the plurality of columnar portions 2B extends in the direction y, and is arranged at equal intervals in the direction x. The plurality of columnar portions 2A and 2B are integrally connected at a location where they intersect each other. Thereby, the light guide member 1 is made into mesh shape in planar view.

  As shown in FIG. 2, the columnar portion 2A has an incident surface 3A, a reflecting portion 4A, and an exit surface 5A, and the thickness distribution in the direction z becomes thinner from both ends in the direction x toward the center in the direction x. Yes. The incident surfaces 3A are both end surfaces of the columnar portion 2A, and are surfaces on which light from the LED unit 6 is incident. 4 A of reflection parts are provided in the direction z lower end of the columnar part 2A, and are comprised by several groove | channel 4Aa. Each of the plurality of grooves 4Aa extends in the direction y and is arranged in the direction x. The reflection unit 4A functions to reflect light incident from the incident surface 3A upward in the direction z. The exit surface 5A is the upper end surface in the direction z of the columnar portion 2A, and is a surface that emits the light reflected by the reflecting portion 4A upward in the direction z.

  As shown in FIG. 3, the columnar portion 2B has an incident surface 3B, a reflecting portion 4B, and an exit surface 5B, and the thickness distribution in the direction z decreases from both ends in the direction y toward the center in the direction y. Yes. The incident surfaces 3B are both end surfaces of the columnar portion 2B, and are surfaces on which light from the LED unit 6 is incident. The reflecting portion 4B is provided at the lower end in the direction z of the columnar portion 2B, and is configured by a plurality of grooves 4Ba. Each of the plurality of grooves 4Ba extends in the direction x and is arranged in the direction y. The reflector 4B functions to reflect light incident from the incident surface 3B upward in the direction z. The emission surface 5B is the upper end surface in the direction z of the columnar portion 2B, and is a surface that emits the light reflected by the reflection portion 4B upward in the direction z.

  In the present embodiment, a portion of the reflecting portions 4A and 4B where the plurality of columnar portions 2A and 2B intersect each other has a stepped shape depending on the location. This is because the thickness in the direction z of the portion where a certain columnar portion 2A and a certain columnar portion 2B intersect is the thicker of any thickness.

  For example, the columnar portion 2A shown in FIG. 2 intersects a portion relatively close to the end portion in the direction y among the plurality of columnar portions 2B. The portion near the end in the direction y of the columnar portion 2B is a portion where the thickness in the direction z is relatively thick. The thickness of the intersecting portion of the columnar portion 2A and the plurality of columnar portions 2B shown in the figure is adjusted to the thickness of the columnar portion 2B. For this reason, in the columnar part 2A shown in this drawing, a step is generated at the intersection with the plurality of columnar parts 2B. On the other hand, the columnar portion 2B shown in FIG. 3 intersects the central portion in the direction x of the plurality of columnar portions 2A. The central portion in the direction x of the columnar portion 2A is the portion having the smallest thickness in the direction x. For this reason, the remarkable level | step difference is not formed in the reflection part 4B of the columnar part 2B shown by this figure.

  The plurality of LED units 6 are light sources of the planar light source device A, and are disposed in front of the incident surfaces 3A and 3B. As shown in FIGS. 2 and 3, the LED unit 6 includes a substrate 61, an LED chip 62, a case 63, and a translucent resin 64. The substrate 61 is an insulating substrate made of glass epoxy resin, for example. The LED chip 62 has, for example, an n-type semiconductor layer, a p-type semiconductor layer, and an active layer sandwiched between them, and is configured to emit blue light, for example. The case 63 is made of, for example, a white resin and surrounds the LED chip 62. The translucent resin 64 covers the LED chip 62. For example, a fluorescent material is mixed in a transparent epoxy resin or silicone resin. This phosphor material emits yellow light when excited by blue light from the LED chip 62. The LED unit 6 can emit white light by mixing blue light and yellow light.

  Next, the operation of the planar light source device A will be described.

  According to the present embodiment, light is emitted from the plurality of columnar portions 2A and the plurality of columnar portions 2B that are orthogonal to each other. For example, when planar light is configured by transmitting such light through a diffusion filter, it is possible to prevent the luminance distribution of the planar light from becoming a plurality of stripes extending in one direction. Therefore, it is possible to make the luminance distribution of the planar light from the planar light source device A uniform. For example, the planar light source device A can uniformly display an image of a liquid crystal display device used as a backlight. it can.

  By adjusting the thickness of the intersecting portions of the plurality of columnar portions 2A and 2B to either thicker one, the thickness of the intersecting portions is extremely thin when the columnar portions 2A and 2B are observed in the longitudinal direction. There is nothing. If there is an extremely thin portion in the longitudinal direction, the light traveling in the longitudinal direction in the columnar portions 2A and 2B is totally reflected by the thin portion or penetrates from the light guide member 1. It will be. According to the planar light source device A, there is no possibility that light is unduly reflected or penetrated at the intersections between the plurality of columnar portions 2A and 2B. This is suitable for making the luminance distribution of the planar light from the planar light source device A uniform.

  The planar light source device according to the present invention is not limited to the above-described embodiment. The specific configuration of each part of the surface light source device according to the present invention can be varied in design in various ways.

  The reflecting portions 4A and 4B are not limited to those constituted by the plurality of grooves 4Aa and 4Ba, and may be constituted by fine irregularities or by providing a reflective film. The columnar portions 2A and 2B are not limited to a rectangular cross section, and may be, for example, a substantially circular cross section. In addition to disposing the LED units 6 at both ends of the columnar portions 2A and 2B, the LED units 6 may be disposed only at one end side of the columnar portions 2A and 2B. The columnar portions 2A and 2B may have a shape with a constant thickness.

It is a top view which shows an example of the planar light source device which concerns on this invention. It is sectional drawing which follows the II-II line | wire of FIG. It is sectional drawing which follows the III-III line of FIG. It is sectional drawing which shows an example of the conventional planar light source device.

Explanation of symbols

A A planar light source device x (first) direction y (second) direction z (third) direction 1 Light guide member 2A (first) columnar portion 2B (second) columnar portions 3A, 3B Incident Surface 4A, 4B Reflection part 4Aa, 4Ba Groove 5A, 5B Output surface 6 LED unit (light source)
61 Substrate 62 LED chip 63 Case 64 Translucent resin

Claims (1)

A planar light source device that emits planar light spreading in first and second directions that are perpendicular to each other in a third direction that is perpendicular to both the first and second directions,
Each extending in the first direction, a plurality of first columnar portions arranged in the second direction, each extending in the second direction, and arranged in the first direction. And a plurality of second columnar portions connected to each other at intersections, and
Each of the first and second columnar parts is provided with an incident surface provided at least on one end side, a reflecting part provided on one side in the third direction, and provided on the other side in the third direction. A light guide member formed with a light exit surface;
A plurality of light sources facing the entrance surfaces of the plurality of first and second columnar portions;
A planar light source device comprising:

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