Light guide plate, planar illuminator using the same and liquid crystal display apparatus

Abstract

The invention provides a light guide plate, a planar illuminator using the same and a liquid crystal display apparatus. The light guide plate made of a transparent resin is used for converting light of light sources into planar light. The light guide plate comprises a light exit plane having a rectangular outer shape; four light entrance planes which are connected to four sides of the light exit plane and are substantially orthogonal to the light exit plane; and a backside which is planes opposed to the light exit plane and includes four inclined planes inclined to be farther from the light exit plane toward a center from the four light entrance planes, wherein a minimum thickness is in the four light entrance planes and a maximum thickness is in the center from the four light entrance planes.

Description

[0001] This application is a divisional application of an invention patent application with an application date of June 13, 2007, an application number of 200780022482.9, and an invention title of "light guide plate, light guide plate assembly, planar lighting device using them, and liquid crystal display device" . technical field [0002] The present invention relates to a light guide plate for converting light from a light source such as a point light source or a linear light source into planar light; Specifically, it relates to a light guide plate for uniformly emitting planar illumination light with a large illumination area, a light guide plate assembly capable of maximizing light utilization efficiency and front brightness, and a method using them A planar lighting device that has a large lighting area and improves in-plane uniformity to illuminate indoors and outdoors, or a planar lighting used as a backlight for liquid crystal display panels of liquid crystal display d...

AI Technical Summary

Problems solved by technology

[0018] First, since the light from the light source enters from the side end surface of the light guide plate, there is a limit to the amount of incident light, and it is difficult to obtain high-brightness illumination light

[0019] Second, since the outer diameter of the currently available fluorescent tubes is at least about 2.0 mm, it is difficult to make the thickness of the light guide plate thinner than the outer diameter of the fluorescent tube, and as a result, it is difficult to further reduce the thickness of the light guide plate

However, as in the aforementioned Patent Documents 2, 3, and 4, in general, in the technology of planar lighting devices such as a light guide plate using LEDs as a light source, and a light guide plate type BLU, in addition to the problems of the light guide plate type BLU using fluorescent lamps, In addition, there are problems that it is difficult to reduce thickness and increase size due to the following reasons or problems

[0022] First, there is a limit to the light guide length of a side-light light guide plate such as a flat plate or a wedge shape, and the in-plane uniformity of the brightness of the exit surface and the brightness of the light-emitting surface cannot be fully achieved

[0023] Second, in the light guide plate of the conventional side light type, when the light from the light source is incident from one side end face or both end faces, due to the arrangement pitch of the LEDs, the luminous density (lm / m 2 ) has a limit, so there is also a limit to the amount of incident light

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