JP2003141924A - Lighting unit and liquid crystal display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively transmit light from a light source to a liquid crystal display panel. SOLUTION: By making a lamp cover 7 in a shape with several pressurized positions with the use of elastic force of a material, warping of a reflector 3 and a reflecting sheet 4 is suppressed and the reflecting sheet 4 is made adhered to a light guide plate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination unit used in a liquid crystal display device for displaying characters and images and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art A liquid crystal display device is a cathode ray tube (cathode ray tube).
Compared with, it has small size, light weight, and low power consumption.
A variety of liquid crystal display devices have been commercialized and become widespread due to advances in development and manufacturing technologies. In many of these liquid crystal display devices, in order to realize a bright display screen, illumination light is applied from the back of the display element by a built-in illumination unit.

In this illumination unit, an edge light system in which a light guide plate is placed on the back surface of a display element and a line light source such as a cold cathode tube is arranged on the end surface of the light guide plate is thin and excellent in brightness uniformity on the light emitting surface. As a backlight system of a liquid crystal display device used in a notebook personal computer or the like, an edge light system is often adopted in consideration of thinness.

A conventional illumination unit and a liquid crystal display device will be described below with reference to FIGS. 1 and 2.

FIG. 1 is an exploded perspective view of an edge light type illumination unit UT in which conventional light sources are arranged on both sides of a light guide plate, and a liquid crystal display device L having the same, and FIG.
3 is a cross-sectional view of the liquid crystal display device L. FIG. This illumination unit UL is emitted from the flat light guide plate 1 that propagates light to the entire back surface of the liquid crystal display panel 6, the light source 2 arranged on one side surface of the light guide plate 1, and the light source 2. Light guide plate 1
A reflector 3 that guides the end face 1a of the light guide plate 1; It is distributed. These light guide plates 1,
The light source 2 and the like are held by the housing 5, and the lamp cover 7 fixes the reflector 3 and the reflection sheet 4 to the housing 5 to form the lighting unit UT.

The light guide plate 1 is formed of a material such as transparent acrylic having optimum optical characteristics represented by the transmittance and the refractive index necessary for light transmission. The reflection sheet 4 has a role of returning the light emitted from the light guide plate 1 to the inside of the light guide plate 1 again and increasing the illumination light emitted from the emission surface. As the reflection sheet 4, a white resin film having a high reflectance is used.

The reflector 3 efficiently causes the light from the light source 2 to enter the incident end face 1a of the light guide plate 1, and is bent so as to surround the light source 2 in a U-shape or a horizontal U-shape. The reflector 3 is formed integrally with the reflection sheet 4 by bending the reflection sheet 4 around the light source 2 (this portion is a "reflector") into a substantially U-shape or a horizontal U-shape. There is also.

The housing 5 is disposed close to the side surface of the reflector 3 so as to surround it from above. Housing 5
Plays a role as a holder for the reflector 3 and also has a role for holding the liquid crystal display panel 6, the light source 2 and the light guide plate 1. The housing 5 is made of, for example, a polycarbonate resin or the like in a plastic shape or a film shape in order to reduce the weight of the liquid crystal display device L.

The lamp cover c is mainly made of a metal such as stainless steel (SUS) or aluminum, and when the reflection sheet 4 is brought into close contact with the light guide plate 3, the lamp cover c is separated from the light source through the gap between the light guide plate 1 and the reflection sheet 4. It has a role of preventing light from leaking out. It also has a role of suppressing the warp of the reflector and efficiently conducting the light from the light source 2 to the liquid crystal display panel.

The illuminating unit UT having such a structure is a liquid crystal display device L in which the liquid crystal display panel 6 is arranged above the illuminating unit UT and the metal front frame 8 is attached thereto.
In the liquid crystal display device L, the light emitted from the light source 2 is guided to the light guide plate 1 directly or after being condensed by the reflector 3.
By being evenly transmitted to the entire back surface of the liquid crystal display panel 6, the characters and images displayed on the display surface 6a of the liquid crystal display panel 6 become visible.

FIG. 3 shows a typical shape of the conventional lamp cover 7. Both ends of the processed plate are fixed to the frame with screws so that the reflector 3 and the reflection sheet 4 are pressed against the liquid crystal display panel side 6.

[0012]

However, in the structure of the conventional example shown in FIG. 3, only the housing 5 is provided at both ends thereof.
However, there is a problem in that the reflector 3 tends to spread due to the elastic force of the material in the rearward direction and the reflection sheet 4 cannot be sufficiently adhered to the light guide plate 1. When the pressure applied to the reflection sheet 4 is insufficient, a gap is formed between the light guide plate 1 and the reflection sheet 4, and the light from the light source 2 leaks to the outside, which causes unevenness in light emission in the display unit, and the liquid crystal display panel is There was a problem that the characters and images displayed were difficult to see.

Further, if the side surface of the back surface of the reflector 3 that effectively transmits the light from the light source 2 to the light guide plate runs along, the light leaks out of the liquid crystal display device L, resulting in inefficient light transmission, and Light unevenness occurs on the liquid crystal display screen. Further, if the width of the lamp cover 7 is narrowed so as to suppress the spread of the reflector 3, it becomes impossible to suppress the warpage of the reflection sheet.

From the above, in order to efficiently transmit the light from the light source 2 to the liquid crystal display panel 6, the light leaks from between the light guide plate 1 and the reflection sheet 4 or between the reflector 3 and the reflection sheet 4. It is necessary to devise the shape of the lamp cover 7 so that it will not occur.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above conventional problems and to provide an illumination unit capable of eliminating display unevenness and efficiently transmitting light to a liquid crystal display panel, and a liquid crystal display device using the same. .

[0016]

In order to solve the above-mentioned problems, an illumination unit according to claim 1 of the present invention comprises a light source,
A light guide plate for guiding the light from the light source, a reflector arranged to surround the light source and reflecting the light in the direction of the light guide plate,
In a lighting unit including a lamp cover for fixing a reflector and a reflection sheet, and a housing arranged so as to surround the reflector, a rectangular bent and bent portion for pressurization is formed in the lamp cover.

According to the present invention, the plurality of bent and raised portions provided on the lamp cover serve as the pressing positions, and the reflector can be effectively fixed from the plurality of pressing positions.

A lighting unit according to a second aspect of the present invention is characterized in that a U-shaped cutout portion is provided to the plurality of bent and raised portions provided on the lamp cover according to the first aspect.

According to the present invention, it is possible to pressurize the reflector and the reflection sheet at the same time and to give the pressing force a degree of freedom.

A liquid crystal display device using an illumination unit according to claim 3 of the present invention is the illumination unit according to claim 1 or 2, and a liquid crystal display panel disposed above the illumination unit. It is characterized by including.

According to the present invention, since the light from the light source can be efficiently and evenly transmitted to the liquid crystal display panel in the illumination unit, a liquid crystal display device using the illumination unit with low power consumption and high reliability is obtained. .

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) As shown in FIG. 1, a lighting unit UT of the present embodiment has a light source 2 and a light source 2.
A plate-shaped light guide plate 1 for transmitting light from the light source, a reflector 3 arranged to surround the light source 2 and reflecting light in the direction of the light guide plate 1, and a housing 5 arranged to surround the reflector 3. , A reflector 3 and a lamp cover 7 that fixes the reflection sheet 4 so as to press it from the back surface. The light source 2 is a fluorescent discharge tube 2 which is driven by a high frequency alternating current (40 to 100 kHz) and emits light. The light source 2 of the present embodiment has one lamp arranged on one side surface of the light guide plate 1, but two lamps are arranged, and one lamp or plural lamps are arranged on both left and right side surfaces of the light guide plate 1. Or one of the four sides of the light guide plate 1 arranged in an L shape on two sides (“L
There is a "shaped fluorescent discharge tube"), etc., and both are called edge light systems.

The light guide plate 1 is made of a material such as acrylic which has optimum optical characteristics represented by the transmittance and the refractive index required for light transmission. The light guide plate 1 has a back surface provided with a dot pattern or groove pattern (not shown) whose shape is changed according to the distance from the light source 2.

The reflection sheet 4 has a role of increasing the illumination light that returns the light emitted from the back surface of the light guide plate 1 back into the light guide plate 1, and is arranged along the back surface of the light guide plate 1. ing. A white resin film having a high reflectance is used for the reflection sheet 4.

The housing 5 is arranged close to the side surface of the reflector 3 so as to surround it from above. Housing 5
Serves as a holder for the reflector, and also serves to hold the liquid crystal display panel 6, the light source 2 and the light guide plate 1. The housing 5 is made of, for example, a polycarbonate resin in a plastic shape or a film shape.

The lamp cover 7 is mainly made of metal such as SUS or aluminum, and when the reflection sheet 4 is brought into close contact with the light guide plate 3, the light from the light source comes out from the gap between the light guide plate 1 and the reflection sheet 4. It has a role to prevent leakage.
It also has a role of suppressing the warp of the reflector and efficiently conducting the light from the light source 2 to the liquid crystal display panel.

FIG. 4 shows the shape of the lamp cover according to the present invention. The lamp cover of the present invention has a bent and raised portion 7a. FIG. 5 is a sectional view showing a state of the rectangular portion 7a of the lamp cover, the reflection sheet 4, and the light guide plate 1 in the embodiment of the present invention. According to the embodiment of the present invention, the flat shape of the lamp cover is changed to the rectangular shape and bent to raise the reflection sheet 4 at the plurality of pressing positions by using the elastic force as shown in FIG. By applying pressure from the light guide plate 1
And the reflection sheet 4 can be closely attached, and light can be prevented from leaking through the gap.

The illumination unit UT having such a structure is a liquid crystal display device L in which the liquid crystal display panel 6 is arranged above it and the metal front frame 8 is attached thereto.
In the liquid crystal display device L, the light emitted from the light source 2 is guided to the light guide plate 1 directly or after being condensed by the reflector 3.
By being evenly transmitted to the entire back surface of the liquid crystal display panel 6, the characters and images displayed on the display surface 6a of the liquid crystal display panel 6 become visible.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings. FIG. 6 is a shape diagram of a lamp cover showing a second embodiment of the present invention. The lamp cover 7 has a U-shaped portion 7b obtained by cutting out the rectangular portion 7a of the lamp cover according to the first aspect. The reflector pressing portion 7c has an effect of suppressing the warp of the reflector 3 in the back direction. The pressing force can be freely adjusted by changing the length of the reflector pressing portion 7c. It has the effect of pressing the reflection sheet at the same time as the reflector.

[0031]

In the lighting unit of the present invention and the liquid crystal display device using the same, the reflector and the reflection sheet can be brought into close contact with each other by using the lamp cover according to the present invention, whereby light leakage can be prevented and a light source can be provided. The light from the can be effectively transmitted to the liquid crystal panel.

[Brief description of drawings]

FIG. 1 is a block diagram of a liquid crystal display device.

FIG. 2 is a sectional view of a liquid crystal display device.

FIG. 3 is a rear view of a conventional liquid crystal display device.

FIG. 4 is a shape diagram of a lamp cover according to the first embodiment of the present invention.

FIG. 5 is an operation diagram of the lamp cover according to the embodiment of the present invention.

FIG. 6 is a sectional view of the embodiment of the invention described in claim 1.

FIG. 7 is a shape view of a lamp cover according to an embodiment of the present invention described in claim 2.

[Explanation of symbols]

1 Light guide plate 1a Light guide plate entrance end face 2 light sources 3 reflector 4 Reflective sheet 5 housing 6 Liquid crystal display panel 6a Back side of liquid crystal display panel 7 lamp cover 7a Bending and raising part of lamp cover 7b Lamp cover hollow 7c Reflector pressurizing part of lamp cover 7 7d Reflection sheet pressurizing part of lamp cover

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiyuki Tsubota             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 2H089 HA40 JA10 QA02 QA06                 2H091 FA14Z FA23Z FA42Z FB02                       FB08 FC19 FD06 FD13 FD18                       LA02 LA18                 5G435 AA03 BB12 BB15 EE23 EE27                       FF03 FF08 FF12

Claims (3)

[Claims] 1. A light source, a light guide plate that guides light from the light source, a reflector that surrounds the light source from three sides, and a reflector that reflects light from the light source toward the light guide plate. In a lighting unit including a lamp cover that fixes a reflector and a housing that surrounds the reflector, a plurality of bent and bent portions are formed in the lamp cover. 2. The lighting unit according to claim 1, wherein a bent and raised portion formed on the lamp cover is hollowed out. 3. A liquid crystal display device comprising the illumination unit according to claim 1.