JPH08179322A - Backlight unit for liquid crystal display device - Google Patents

Abstract

PURPOSE: To inexpensively and easily realize a backlight unit for a liquid crystal display device. CONSTITUTION: This backlight unit for a liquid crystal display device includes a light transmission body 3, one or more light sources 5 provided on one or more side surface sides of the light transmission body 3, and a uniformizing means capable of constituting a nearly uniform high-luminance light emission diffusing surface by dispersing light made incident on the light transmission body 3. The uniformizing means is concurrently formed on at least one surface of the light transmission body 3 at the time of molding the light transmission body 3 and constituted by including a part 9 having a cross section perpendicular to incident light, which is formed to be zigzag.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit for a liquid crystal display device.

[0002]

2. Description of the Related Art Since a liquid crystal display device is a passive element in which liquid crystal does not emit light by itself, a separate light source is required from the viewpoint of easy viewing. Therefore, a liquid crystal display device is usually composed of a liquid crystal display unit (liquid crystal panel) and a backlight unit, and both units are manufactured separately and then placed on the back side of the liquid crystal display unit to illuminate from the back side (back side). Is
A backlight unit is attached.

Such a backlight unit includes a lamp that emits light and a light guide plate that irradiates the light of the lamp that is incident from the side to the entire panel surface of the liquid crystal display unit.
And. Then, in order to realize uniform irradiation (improvement / uniformization of luminance distribution) on the lower surface of the light guide plate,
A rough surface (uneven surface) is separately formed by trial and error by post-processing (for example, silk printing or cutting) after injection molding of the light guide plate.

[0004]

However, the above-mentioned conventional structure is not sufficient for obtaining high brightness, and it is expected that a light guide plate structure capable of realizing the structure more easily and cheaply will appear. Therefore, it is an object of the present invention to provide a backlight unit that is inexpensive, simple, and capable of realizing high brightness.

[0005]

In order to solve the above problems, the present invention provides a light guide, one or more light sources which can be provided on one or more side surfaces of the light guide, and a light guide. A uniforming means capable of dispersing light to form a substantially uniform high-intensity light emitting diffusion surface, and a backlight unit for a liquid crystal display device, wherein the uniformizing means is a light guide body during molding of the light guide body. Is structurally characterized in that it is formed on at least one of the surfaces simultaneously and has a portion having a zigzag cross section perpendicular to the incident light.

[0006]

The zigzag-shaped portion of the uniformizing means for forming a substantially uniform light-emitting diffusion surface is simultaneously formed on at least one surface of the light guide body during molding of the light guide body. In addition, it is possible to save the time and effort for post-processing (additional work). Further, since the zigzag portion effectively collects light, it is possible to obtain high brightness with low power consumption while uniforming the brightness distribution on the light emitting diffusion surface.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Referring to FIG. 1, in the backlight unit 1 of the present embodiment, a light guide unit, for example, a light guide plate 3 having a rectangular shape (transverse cross section) when viewed from above is disposed inside the backlight unit 1. On the side, a light source, for example, a round rod-shaped lamp 5 (for example, a cold cathode tube) is arranged in parallel.

The lamp 5 is provided only on one side (back side) of the light guide plate 3, but it can be provided on another side part instead of or in addition to it, and is composed of a plurality of lamps. You can also The lamp holder 13 that covers the lamp 5 has a curved surface (reflection cover surface) 1 like a vertically divided cylinder so that the light from the lamp 5 can enter the light guide plate 3 without waste.
3a and can be formed by injection molding a highly reflective molding material. Note that the lamp holder may be configured to include a multi-faced portion (not shown) including a plurality of flat surfaces instead of the curved surface 13a. As the high reflection molding material, for example, polycarbonate (P
C) or a resin obtained by adding an ABS resin thereto may be used, but more practically, for example, S3100 (PC / ABS) manufactured by Daicel Chemical Industries, Ltd. is used.
With this lamp holder, leakage current (and thus brightness reduction) can be substantially eliminated.

A light diffusing plate 7 for increasing the amount of diffusion is attached to the upper side (diffusion surface side) of the light guide plate 3, and a light reflecting plate for auxiliary increasing the amount of light emission is provided below the light guiding plate 3. 11 can be attached. Now, the light guide plate 3 forming the essential part of this embodiment will be described in detail below.
As shown in FIG. 1, it has a one-sided wedge shape in which the wall thickness gradually decreases as it goes away from the lamp 5 in the vertical direction.
However, the present invention is not limited to this, and may have a vertical cross-sectional shape (not shown) such as a uniform flat plate shape, a concave shape, a convex shape, a U shape, a V shape, or both wedge shapes.

As shown in FIG. 1, the upper surface of the light guide plate 3 has a cross-section parallel to the lamp 5 (in other words, a cross section perpendicular to the incident light) and has a continuous sharp mountain shape, that is, a zigzag portion 9. (Equalizing means). The zigzag portion 9 is a means for improving the luminance distribution and is provided on the upper surface of the light guide plate 3 in this embodiment, but it may be provided instead of or in addition to the lower surface. It should be noted that a rough surface 19 by silk pattern printing is additionally / additionally formed on the lower surface of the light guide plate 3 of the present embodiment in order to further improve the luminance distribution in a separate post process. It is not an essential element for establishment. Further, instead of silk printing, injection molding irregularities such as an etching grain pattern are formed in a zigzag-shaped portion 9 on the upper surface.
It can also be formed in the same way.

The light guide plate 3 having such a characteristic zigzag portion 9 is not formed by additionally performing cutting work, but an injection mold (not shown) for forming the light guide plate. Zigzag portion (not shown) corresponding to
By forming them, they are simultaneously formed and configured at the same time when manufacturing (molding) the light guide plate. Examples of materials for injection molding the light guide plate 3 include polycarbonate (PC) and P
MMA or the like may be used, but more practically, for example,
Delpet 80NR (PMMA) manufactured by Asahi Kasei Corporation can be used.

In this embodiment having the above configuration,
It is possible to form the zigzag portion (uniformizing means) at the same time as the manufacturing of the light guide plate, without the need for post-processing that is required for the light guide plate. That is, the luminance distribution on the light-emitting diffusion surface of the light guide plate can be favorably made uniform (luminance unevenness can be eliminated), and thus such an excellent light guide plate (and thus the backlight unit) can be manufactured in large quantities at a low cost. In addition, it can be manufactured easily and accurately, is practical and practical, and is extremely preferable.

Finally, FIG. 2 shows an example of the result of a comparison experiment between the structure of this embodiment and the conventional structure concerning the viewing angle characteristics at the center of the backlight unit. In the same figure, the value of the conventional unit in the vertical direction (0 °) is set to 100, but it will be well understood that the structure of this embodiment succeeds in obtaining high brightness. In addition, the angle of the top of the zigzag portion is 95 °.
However, it was confirmed that good brightness was obtained in the range of about 50 ° to 150 °.

[0014]

As described above, according to the present invention, a large number of backlight units can be realized inexpensively and easily without any inconvenience, which is extremely rational and economical.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an embodiment of a backlight unit according to the present invention.

FIG. 2 is a diagram showing an experimental comparison result between the structure of the present embodiment and the conventional structure.

[Explanation of symbols]

 1 ... Backlight unit 3 ... Light guide plate 5 ... Lamp 7 ... Light diffusing plate 9 ... Zigzag portion 11 ... Light reflecting plate 13 ... Lamp holder 13a ... Curved surface 19 ... Rough surface

Claims (1)

[Claims] 1. A light guide (3), one or more light sources (5) that can be provided on one or more side surfaces of the light guide (3), and light incident on the light guide (3) is dispersed. And a uniformizing means capable of forming a substantially uniform high-intensity light-emitting diffusion surface, the backlight unit for a liquid crystal display device, wherein the uniformizing means is used for molding the light guide body (3). A backlight unit for a liquid crystal display device, comprising a portion (9) simultaneously formed on at least one surface of (3) and having a zigzag cross section perpendicular to incident light.