JP2007273325A - Light guide plate and surface light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide plate capable of uniformly diffusing light emitted from a plurality of point light sources, and having high emission efficiency; and to provide a surface light source device equipped with the light guide plate. <P>SOLUTION: In this light guide plate 1, a plurality of light reflecting grooves 3 each used for introducing light emitted from the plurality of point light sources 2, 2 to diffuse and emit it from a surface thereof are arranged thereon by dispersing them. The light reflecting grooves 3 comprise a plurality of V-shaped grooves 31 and 32 having, on one-side slant faces, reflecting surfaces 3a, 3a formed in directions respectively perpendicular to the plurality of point light sources 2, 2; and the reflecting surfaces 3a, 3a of the light reflecting grooves 3 are formed to increase the areas thereof in proportion to the distances from the point light sources 2, 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light guide plate and a surface light source device for uniformly irradiating a liquid crystal display plate such as a personal computer, a word processor, and a liquid crystal television.

  The surface light source device is provided with, for example, a light source composed of an LED or the like, a light guide plate that introduces light emitted from the light source, disperses the light on a liquid crystal panel, and emits the light. For example, the light guide plate is made of a transparent resin material such as polycarbonate resin or methacrylic resin, and the reflection plate is made of a white resin sheet or the like having a high reflectance and is attached to the back side of the light guide plate.

In such a surface light source device, a plurality of point light sources are provided by arranging groove-shaped prisms in a predetermined pattern so that light emitted from a point light source such as an LED is evenly distributed on the surface of the light guide plate Has proposed a configuration in which a pattern corresponding to each light source is arranged for each area (see, for example, Patent Document 1).
Japanese Patent No. 3151830

  However, in the above-described conventional surface light source device, the light emitted from each light source cannot be diffused beyond the respective areas, so that the total irradiation efficiency is lowered. In addition, since a portion (dark portion) with low luminance (or lightness) is generated at the boundary position of each area, there is a problem that luminance unevenness and color unevenness easily occur on the liquid crystal display panel.

  This invention is made in view of such a situation, and provides the surface light source device provided with the light guide plate with the high irradiation efficiency which can diffuse uniformly the light irradiated from several point light sources, and the light guide plate. With the goal.

  (1) The light guide plate of the present invention is a light guide plate in which a plurality of reflection grooves for dispersing light emitted from a plurality of point light sources from the end face and diffusing from the surface are distributed on the surface. Each of the reflection grooves is disposed with a gap between each other, and is formed in a direction orthogonal to any of the plurality of point light sources, and is formed in a direction orthogonal to a specific point light source. Further, the reflection groove formed in a direction orthogonal to a point light source other than the specific point light source is formed in the gap between the reflection grooves.

  According to such a configuration, the reflection grooves that are perpendicular to the point light sources other than the specific point light source are disposed in the gap between the reflection grooves that are perpendicular to the specific point light source. Since the light is distributed on the surface of the light guide plate, the light emitted from each point light source is diffused without being biased toward a specific area, and uneven brightness is less likely to occur. improves.

  (2) The reflection groove formed in a direction orthogonal to the specific point light source and the reflection groove formed in a direction orthogonal to the point light source other than the specific point light source are connected to each other. May be formed. In this way, it is possible to form a continuous reflection groove by connecting the reflection grooves vertically opposed to different point light sources, so when forming the reflection groove, a cutting jig is formed at each reflection groove joint. By simply changing the direction, it becomes possible to form the reflective grooves in a single process, and the man-hours can be reduced.

  (3) The length of the reflection groove may be formed so as to increase in proportion to the distance from the point light source. In this way, in the part away from the point light source, the size of the reflection groove corresponding to the surface becomes large, so that the amount of reflected light becomes large and the decrease in luminance (or brightness) is compensated for from the point light source. Regardless of the distance, uniform luminance can be obtained on the liquid crystal display panel.

  (4) A surface light source device according to the present invention includes a light guide plate according to any one of (1) to (3), a point light source for irradiating light to the light guide plate, and a back surface of the light guide plate. And a reflector disposed on the side.

  According to such a configuration, it is possible to provide a surface light source device with little luminance unevenness without the light emitted from each point light source being biased to a specific area.

  According to the light guide plate of the present invention, the reflection grooves that are perpendicular to the point light sources other than the specific point light source are arranged in the gap between the reflection grooves that are perpendicular to the specific point light source. Are distributed on the surface of the light guide plate, the light emitted from each point light source will be diffused without being biased to a specific area, making it difficult for uneven brightness to occur and the irradiation efficiency. Will also improve.

  In addition, if a reflection groove formed in a direction perpendicular to a specific point light source and a reflection groove formed in a direction orthogonal to a point light source other than the specific point light source are connected to each other, Since it can be formed in one continuous reflection groove, it is possible to form the reflection groove in a single process only by changing the direction of the cutting jig at the joint of each reflection groove when forming the reflection groove. Can be reduced.

  In addition, if the length of the reflection groove is formed so as to increase in proportion to the distance from the point light source, the size of the reflection groove corresponding to the surface becomes large at a part away from the point light source. For this reason, the amount of reflected light is increased, and a decrease in luminance (or lightness) is compensated for, and uniform luminance (or lightness) is obtained on the liquid crystal display panel regardless of the distance from the point light source.

  According to the surface light source device of the present invention, it is possible to provide a surface light source device with less luminance unevenness without the light emitted from each point light source being biased to a specific area.

  Hereinafter, the light guide plate and the surface light source device according to the preferred embodiment of the present invention will be described in detail.

  FIG. 1 shows a light guide plate, (a) is a plan view of the light guide plate, and (b) is a plan view of a reflection groove. In the figure, reference numeral 1 denotes a light guide plate made of a resin material or the like having a large light refractive index, 2 denotes a point light source made of LED or the like, 3 denotes a reflection groove formed in the light guide plate 1, and a rear surface of the light guide plate 1 (light emission) The light emitted from the point light source 2 is taken in from the end face of the light guide plate 1 and diffused from the surface to be emitted. The light source 2 includes two point light sources 21 and 22.

  The reflection groove 3 includes a reflection groove 31 formed in a direction orthogonal to the point light source 21 and a reflection groove 32 formed in a direction orthogonal to the point light source 22. They are connected to each other to form a single reflection groove 3. The lengths of the reflection grooves 31 and 32 are formed so as to increase in proportion to the distances from the respective point light sources 21 and 22. Each of the reflection grooves 31 and 32 is formed in a V-shaped cross section having reflection surfaces 3a and 3a on one side slope. Such reflection grooves 3 are distributed on the surface of the light guide plate 1.

  A reflector (not shown) is disposed on the back side of the light guide plate 1 and a liquid crystal display (not shown) is disposed on the front side.

  According to such a configuration, each reflection groove 31, 32 is vertically opposed to the two point light sources 21, 22, and the reflection groove 3 composed of these reflection grooves 31, 32 is dispersed in the light guide plate 1. Therefore, the light emitted from each of the point light sources 21 and 22 is diffused without being biased toward a specific area, so that uneven brightness is less likely to occur and the irradiation efficiency is improved.

  Moreover, since the reflection groove 3 is formed by connecting the reflection grooves 31 and 32 to each other, when the reflection groove 3 is formed, the moving direction of the cutting jig is changed at the connection between the reflection grooves 31 and 32. Thus, the reflection groove 3 can be formed in a single process, and the number of steps for forming the reflection groove 3 can be reduced.

  The light diffusing action of the reflection groove 3 will be described in more detail with reference to FIGS. When the reflection groove 31 or 32 is formed in a direction orthogonal to the point light source 2, the light emitted from the point light source 2 is reflected by the reflection surface 3 a formed on one side slope of the reflection groove 31 or 32. A liquid crystal display panel that is emitted toward the front (see FIGS. 2B and 2C) and disposed on the front side of the light guide plate 1 is irradiated from the back side.

  However, as shown in FIG. 2D, if the reflecting groove 31 or 32 is not formed in a direction orthogonal to the point light source 2, the light emitted from the point light source 2 is reflected on the reflecting surface 3a. The light is hardly emitted toward the front of the object, and does not contribute much as light for irradiating the liquid crystal display panel disposed on the front surface side of the light guide plate 1.

  The reflection groove 3 as described above is manufactured by using, for example, a conical cutting tool 5 as shown in FIG. That is, the angle of the tip of the cutting tool 5 is set so that the reflecting surfaces 3a and 3a of the reflecting grooves 31 and 32 have a predetermined reflection angle, and reflection is performed while rotating the tool 5 as shown in FIG. The light guide plate 1 may be cut by moving along the shape of the groove 3.

  It should be noted that the present invention is not limited to the embodiment, and it is free to make design changes and improvements as necessary, as long as it does not depart from the gist of the invention. For example, the point light source 2 Three or more may be provided. In addition, the reflection grooves 31 and 32 may have any cross-sectional shape as long as the reflection surface 3a can be secured, even if the reflection grooves 31 and 32 do not have a V-shaped cross section. Further, the reflection grooves 31 and 32 do not necessarily have to be connected to each other. For example, the plurality of reflection grooves 31 and 32 are dispersedly arranged on the surface of the light guide plate 1 with a gap between each other. If the reflection groove 32 is formed in the gap, the same effect as in the above embodiment, that is, the effect that the light emitted from the point light sources 21 and 22 is diffused without being biased to a specific area. can get.

  The light guide plate of the present invention provides a uniform luminance distribution, makes it difficult for uneven luminance to occur, and improves the irradiation efficiency, so that a liquid crystal display plate for a personal computer, word processor, liquid crystal television or the like that requires a uniform luminance distribution. It is suitable for the field of surface light source devices that irradiate the light.

  The surface light source device of the present invention provides a uniform luminance distribution and is less likely to cause uneven brightness, and also improves the irradiation efficiency from each point light source to the liquid crystal display panel. It is used in the field of LCD televisions.

It is a top view of the light-guide plate which concerns on embodiment of this invention, (a) is the top view seen from the back side of a light-guide plate, (b) is a top view which expands and shows a reflective groove | channel. It is a figure which shows the reflective groove of the same light-guide plate, (a) is a top view which shows the reflective surface of a reflective groove, (b) is sectional drawing which shows reflection of the light by a reflective surface, (c) is reflection of the light by a light source. FIG. 4D is a sectional view showing reflection of light by a disturbance element. It is the figure which showed the formation process of the reflective groove of the same light-guide plate, (a) is the figure which showed the formation procedure of the reflective groove by a cutting tool, (b) is the perspective view of a cutting tool

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light guide plate 2 Point light source 21, 22 Point light source 3 Reflection groove 31, 32 Reflection groove 3a Reflection surface

Claims (4)

A light guide plate in which a plurality of reflection grooves for dispersing and emitting light emitted from a plurality of point light sources from an end face is emitted from the surface and dispersed on the surface,
Each of the reflection grooves is disposed with a gap between each other, and is formed in a direction orthogonal to any of the plurality of point light sources,
The reflection groove formed in the direction orthogonal to the point light sources other than the specific point light source is formed in the gap between the reflection grooves formed in the direction orthogonal to the specific point light source. Characteristic light guide plate.   The reflection groove formed in a direction orthogonal to the specific point light source and the reflection groove formed in a direction orthogonal to a point light source other than the specific point light source are connected to each other. The light guide plate according to claim 1.   The light guide plate according to claim 1, wherein a length of the reflection groove is formed so as to increase in proportion to a distance from the point light source. A light guide plate according to any one of claims 1 to 3, a point light source for irradiating light to the light guide plate, and a reflector disposed on the back side of the light guide plate. A surface light source device.

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