JPH046584A - Backlighting device - Google Patents

Abstract

PURPOSE:To eliminate the unbalance (irregularity) of brightness and to efficiently utilize light emitting from a light source by making peak and trough parts of a saw tooth shape below a light source different in reflection factor. CONSTITUTION:A saw-tooth undulating reflecting plate 5 is interposed between the light source 2 and a lamp house 1. Namely, a light diffusion plate is incorporated in a saw-tooth shape between a cylindrical light source 2 and the lamp house 1 and a surface display panel 3 is irradiated with the light from the cylindrical light source 2. Further, when this backlighting device is made thin, the light from the cylindrical light source 2 appears intensely on the surface display panel 3 to generate an irregularity in brightness, so the reflection factor of the trough parts of the saw tooth shape below the light source is decreased. Consequently, the loss of the light reaching the surface display panel 3 is reduced, efficient utilization is available and thin size and a uniform brightness distribution are realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Fields] The present invention is applicable to various display elements, particularly word processors, personal computers, computer terminal devices, or
This invention relates to a backlighting device for a liquid crystal display panel of a television or the like.

[Prior Art] Conventionally, a backlighting device using a cylindrical light source has been of the type shown in a perspective view in FIG.

That is, if the light emitted from the cylindrical light source 2 housed in the lamp house 1 is directly irradiated onto the front display panel 3, the brightness on the front display panel 3 will be uneven (111 degrees unevenness).
As a means of correcting this to some extent, a halftone screen (writing curtain) 4 is interposed between the cylindrical light source 2 and the front display panel 3.

However, the dotted screen 4 requires high precision in its mounting position, making it difficult to work with, and it also requires a method that reflects a portion of the light irradiated onto the front display panel. However, there are drawbacks such as the inability to efficiently utilize the light generated from the light source.

[Means for solving the problem] In order to solve this problem, instead of the conventional screen 4 shown in FIG. 2, a serrated reflective plate 5 is inserted between the light source and the lamp house. This solves the above problem.

That is, in FIG. 3, a light diffusing plate is installed between the cylindrical light source 2 and the lamp house 1 in a sawtooth-like undulating shape so that the light from the cylindrical light collection R2 is uniformly and efficiently irradiated onto the front display panel 3. Furthermore, if the backlighting device is made thin, the light from the cylindrical light source 2 will be strongly emitted onto the front display panel 3, causing uneven brightness. By lowering the brightness, uneven brightness is improved.

[Example code of the present invention] An embodiment of this invention will be described based on FIG.

3 in the figure is a front display panel, which in this case is a milky white methacrylic resin plate. 2 is a cylindrical light source, in this case ■Erebam 10FLE-8,253 (AS)
This is a cold cathode tube. 6 is a sawtooth shaped reflector. In this case, a #B color reflector with a high reflectance of 1 reflection + 1!82% is used, and a reflectance of 55 is applied to the sawtooth valley below the light source.
% white reflector was attached only to the diameter of the light source.

The distance between the four cylindrical light sources 2 is 29 mm, the height difference between the sawtooth reflecting plates 5 is 4.5 mm, and the front display panel 3
The distance from to the serrated apex is 8 mm, the distance between each apex is 29 mm, and the apex is curved.

In this example, when one cold cathode tube was lit with a power of 3.6 watts, it was lit at 140 mm and a length of 230 m.
Maximum brightness on surface display panel with m 2500 c
A brightness distribution of d/m' and a minimum brightness of 2060 cd/m2 was obtained.

That is, it was confirmed that the brightness distribution difference was within the range of ±10%.

[Effects of the Invention] By using the backlighting device according to the present invention, it is possible to realize a backlighting device that is thin and has a uniform brightness distribution, which reduces the loss of light that reaches one front display panel, which can be used efficiently. Ta.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conventional backlighting device. I! FIG. 2 is a sectional view showing the position of a dotted screen of a conventional backlighting device. The AS3 diagram is a sectional view showing an embodiment of the present invention. Further, from FIG. 1 to FIG. 113, each symbol in the drawings represents the following. 1: Lamp house, 2: Cylindrical light source, 3: Surface display panel, 4: Screen with halftone dot pattern (lighting curtain), 5: Saw-shaped relief diffuser plate No. 30

Claims (1)

[Claims] A thin, almost parallelepiped lamp house has a surface display panel on the top surface, a plurality of cylindrical light sources are written on the inside of the lamp house, and a sawtooth with a plurality of vertices is provided in the space between the lamp house and the light sources. A backlighting device characterized in that a raised reflector is arranged so that the serrated peaks are located between the light sources, and the reflectance of the serrated valleys and peaks below the light sources is changed.