Sheet light emitting apparatus

Abstract

A sheet light emitting apparatus, incuding a light guiding plate of a translucent material and having light receiving and light emitting surfaces, a light source disposed to face the light receiving surface, and a prism structure provided on the light receiving surface, the prism structure having plural kinds of prisms having different apex angles.

Description

technical field [0001] The present invention relates to a planar light-emitting device that guides light from a light source into a light guide plate, emits it through the light guide plate, and irradiates the entire surface of an illuminated body such as a liquid crystal cell of a liquid crystal display device with the emitted light from the light guide plate. Background technique [0002] In recent years, thin liquid crystal display devices have been used as display devices for notebook word processors, computers or portable telephones, and other portable information terminal equipment. In order to illuminate such a thin liquid crystal display device, a planar light emitting device having a light guide plate is used. The light source of the planar light-emitting device utilizes linear light sources such as fluorescent tubes and point light sources such as multiple light-emitting diodes. Multiple light-emitting diodes (hereinafter referred to as LEDs) are often compacted du...

AI Technical Summary

Problems solved by technology

However, when using a directional LED with strong emission light, for example, JP-A-2002-082625 ( Figure 4 ) has the following disadvantages: a trough of the light propagating inside the light guide plate 31 is generated on the side of the light-emitting LED 32 close to the light guide plate 31 (side of the end surface 31a), and between a plurality of LEDs 32 and their two end produces a triangular part A that light cannot reach

[0009] In the above-mentioned planar light-emitting device using the light guide plate having a plurality of prisms on the light-receiving surface, there is also the following problem: that is, as described above, the light from the LED passes through the plurality of prisms and becomes transmitted through each lens 101P. A plurality of transmitted lights sp, these transmitted lights sp are combined to form a collective beam SK, such a collective beam SK diverges from each LED 102 as shown in FIG. inner marching distribution

and as stated in Figure 14B As in the planar light-emitting device shown in , in order to achieve the purpose of thinning and simplification, in the planar light-emitting device composed of a prism sheet (103) opposite to each other without passing through the diffusion sheet above the light guide plate (101), the above-mentioned The obvious bright lines and the decreased brightness (R in Figure 16A) are easily reflected on the lighting itself, so these will directly make the state of the lighting worse

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