Lighting device and liquid crystal display

Abstract

The present invention relates to an illumination device and a liquid crystal display device. One major surface of a light guide plate (12) is formed, in stripe form in a plan view, with a plurality of prism grooves (14) each consisting of a slight slope and a steep slope. The inclination angles of the slight slope and the steep slope are in ranges of 1 DEG to 10 DEG and 41 DEG to 45 DEG , respectively. The width of the steep slope in the one major surface of the light guide plate increases as the position goes away from a light incident surface of the light guide plate in such a manner that the width of the steep slope amounts to 1.1 to 1.5 at a position farthest from the light incident surface if it is assumed that the width of the steep slope is equal to 1.0 at a position closest to the light incident surface. The invention therefore provides an illumination device which can illuminate a large area brightly and uniformly though its power consumption is low and a liquid crystal display device that is equipped with such an illumination device and is high in luminance and superior in display quality.

Description

technical field [0001] The present invention relates to an illuminating device and a liquid crystal display device, and more particularly to an illuminating device capable of uniformly and brightly illuminating a large area even with a light source of one lamp, and a liquid crystal display device using the same. Background technique [0002] Conventionally, a unit composed of a light source, an intermediate light guide, a light guide plate, and a housing that holds the above together and has a reflective inner surface has been used in a front light of a reflective liquid crystal display device. [0003] Figure 23A is a perspective structural view showing a liquid crystal display device having such a configuration, Figure 23B yes Figure 23A A top view of the liquid crystal display device shown. The liquid crystal display device shown in these figures includes a liquid crystal display unit 120 and a front light 110 provided on the front side of the liquid crystal display u...

AI Technical Summary

Problems solved by technology

[0007] However, in such a 1-lamp type front light, it is almost impossible to uniformly and brightly illuminate a large area of ​​a display screen larger than several inches by a combination of a thin light guide plate and a light-emitting element of 1 lamp.

That is, in Figure 23A In the front light 110 shown, if the light-emitting element 115 is provided on one side, in order to guide the light from the light-emitting element 115 to the light guide plate 112 evenly, it is first necessary to pass the intermediate light guide body 113 on the side of the light guide plate 112. The end surface 112a makes the incident light uniform in the length direction, but because it is difficult to make the incident light of the light guide plate 112 uniform through the intermediate light guide body 113, it is extremely difficult to obtain uniform outgoing light in front of the light guide plate 112

Therefore, when it is particularly conspicuous, an image will be generated on the edge portion (the left edge portion in FIG. 23 ) on the side of the light-emitting element 115 of the light guide plate 112 . Figure 23B The problem of the triangular dark part 118 in the top view is shown, which causes the visibility of the liquid crystal display device to be reduced.

[0008] In this way, although there is a high demand for a front light that uses a light-emitting element of one lamp as a light source, there is no front light that is thin and can uniformly and brightly illuminate a large area.

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