JPH09171173A - LCD panel dustproof device - Google Patents

Abstract

(57) An object of the present invention is to provide a liquid crystal display device which prevents invasion of dust, has little decrease in brightness for long-term use, and is prevented from being contaminated by dust. An image display surface of a liquid crystal panel and a protective plate are filled with a foam rubber material and hermetically sealed. Further, the back surface of the liquid crystal panel, the projection surface of the light source, and the optical path from the backlight formed by the first diffusion plate and the second diffusion plate are sealed with a foam rubber material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to dustproof of a projection type display device using a liquid crystal panel.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display device composed of a liquid crystal panel and a backlight is required to have higher brightness and higher image quality in recent years, and it has become essential for the product quality to increase the brightness of the backlight. In response to this demand, the liquid crystal and the pixel driving element have a problem that their performance is extremely deteriorated at high temperature and as a result, the contrast is lowered. Therefore, even if the brightness is increased, the temperature increase must be reduced. And
Two conflicting issues have been raised. In order to solve this problem, in the conventional liquid crystal display device, the pixel drive electrode of the liquid crystal panel is formed by separating the distance between the backlight and the liquid crystal display panel, inserting the heat absorbing member between the backlight and the liquid crystal display panel. Measures such as a method of suppressing the temperature rise of the pixel driving element by devising the heat transfer coefficient of the material of the glass substrate and the glass substrate on which the counter electrode is formed have been taken. JP-A-5-273535 discloses an example of a method of suppressing the temperature rise of a pixel driving element by devising heat transfer coefficients of materials of a glass substrate having a pixel driving electrode of a liquid crystal panel and a glass substrate having a counter electrode. Is mentioned.

[0003]

However, even if the temperature rise at the time of driving the liquid crystal panel is suppressed by the various methods described above, external dust invades and adheres to the back surface and the front surface of the liquid crystal panel for long-term use. Even if the brightness of the backlight does not decrease, there are a phenomenon in which the brightness of the screen decreases due to stains on the screen and a phenomenon in which the screen is difficult to see due to the stains and the image quality deteriorates. The problem of image deterioration due to invasion and adhesion of dust was not described because it was not described. Dust ingress,
Image deterioration due to adhesion is particularly remarkable when mounted on a vehicle such as a subway, and an object of the present invention is to provide a liquid crystal display device which prevents dust from entering and has little decrease in brightness for long-term use and prevents dust from being contaminated. is there.

[0004]

In order to achieve the above object, the following constitution is adopted.

(1) A transparent protective plate is provided on the front surface of the liquid crystal panel, and a first packing made of a foamed rubber material is put between the surface other than the image display surface of the liquid crystal panel and the protective plate for sealing.

(2) A backlight is provided by providing a distance on the back surface of the liquid crystal panel, a first diffusion plate is provided on the back surface of the liquid crystal panel to close the back surface side of the liquid crystal panel, and a second diffusion plate is provided on the back light projection direction side. A diffusing plate is provided to cover the front side of the light source while diffusing the projection light of the backlight, and the optical path from the backlight formed by the first diffusing plate and the second diffusing plate is made of foamed rubber material. Seal tightly.

(3) The chassis enclosing the liquid crystal panel and the backlight, the first diffusion plate and the second diffusion plate, and the second packing has a plurality of ventilation holes.

The above means have the following effects.

(1) The image display surface of the liquid crystal panel is hermetically sealed to prevent dust.

(2) The backlight is sealed from the rear surface of the liquid crystal panel to prevent dust.

(3) The portions other than the above items (1) and (2) are radiated through the ventilation holes.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings. FIG. 1 shows a perspective view of the liquid crystal display device of the present invention.
Shows a sectional view taken along the line AA of FIG. 1, and FIG. 3 shows an enlarged view of a B portion of FIG.

In each drawing, 1 is a liquid crystal display device, 2 is a chassis, 3 is a liquid crystal panel, 4 is a protective plate, 6 is a stepped screw, 7 is a rear cover, 9 is a first packing,
10 is a ventilation hole, 11 is a fixing metal fitting, 13 is a panel fixing screw, 15 is a backlight, 16 is a fluorescent tube, 20 is a second packing, 21 is a first diffusion plate, 22 is a second diffusion plate, Reference numeral 30 indicates a housing, and symbol a indicates the flow of air.

In FIG. 1, a liquid crystal panel 3 is a chassis 2
Is fixed to the front surface by the panel fixing screw 13, the image display surface 5 of the liquid crystal panel 3 is fixed to the front surface of the chassis 2 by the stepped screw 6 on the protective plate 4, and the first packing 9 is attached to the rear surface of the protective plate 4 and the liquid crystal. The panel 3 is inserted into a surface other than the image display surface 5 on the front side to surround the image display surface 5, and the space formed by the image display surface 5 and the back surface of the protective plate 4 is sealed to prevent dust from entering.
The chassis 2 is made of a metal material having a plurality of air holes 10, and the air inflow / outflow action is performed through the air holes 10 to cool the heat of driving the liquid crystal panel and the heat of internal components such as the backlight 15. It is equipped with fixing metal fittings 11 on both sides. The first packing 9 is a foamed rubber, and in particular, when a continuous foamed rubber is used, it is good in sealing, and is bent and held in contact with the surface other than the image display surface 5 of the liquid crystal panel 3 and the back surface of the protective plate 4. Become. The protective plate 4 penetrates a hole having a diameter larger than the outer shape of the shaft of the stepped screw 6 (not shown), and the thickness of the plate is approximately the same as the length of the shaft of the stepped screw (not shown), The expansion and contraction due to the difference in thermal expansion coefficient between the material of the protective plate 4 and the material of the chassis 2 is absorbed.

In FIG. 2, the back surface of the liquid crystal panel 3 is sealed with a first diffusion plate 21, and a back light 15 is arranged at a distance from the back surface thereof. It is sealed with the second diffusion plate 22. The light projection space formed by the first diffusing plate 21 and the second diffusing plate 22 is located between the respective diffusing plates 21 and 22 around the first diffusing plate 21 or around the second diffusing plate 22. Then, the second packing 20 is bent and attached with an adhesive to seal the inside.
Further, the second packing 20 presses the periphery of the first diffusion plate 21 and the second diffusion plate 22 with a pressing force corresponding to the bending to prevent a gap from being generated due to the deformation of the respective diffusion plates 21 and 22, and is installed. When the temperature of the environment changes drastically and a gap is created, a tape pad is attached to the gap to prevent dust from entering from this part.

In FIG. 3, the inside of the liquid crystal display device 1 is infiltrated by outside air through a ventilation hole 10 provided in the chassis 2 to cool the inside, and the image display surface 5 of the liquid crystal panel 3 and the inside of the liquid crystal panel, the first, Since the diffuser plate 21, the second diffuser plate 22 and the space between them and the interior of the backlight 15 are hermetically sealed, dust does not enter and the image display surface is not deteriorated in brightness and is not stained.

[0017]

As described above, according to the present invention, the image display surface of the liquid crystal panel is hermetically sealed, and the light source (backlight) is hermetically sealed from the back surface of the liquid crystal panel to prevent dust, so that the brightness of the screen is reduced by dust due to long-term use. And the effect of preventing deterioration of image quality due to dirt on the image surface.

[Brief description of the drawings]

FIG. 1 is a perspective view of a liquid crystal display device of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG. 1;

FIG. 3 is an enlarged view of a portion B in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 2 ... Chassis, 3 ... Liquid crystal panel, 4 ... Protective plate, 9 ... First packing, 10 ... Vent hole, 15 ... Backlight, 20 ... Second packing, 21 ... First diffusion Plate, 22 ... Second diffuser plate.

Claims (3)

[Claims] 1. A light source (backlight) on the back of a liquid crystal panel.
In a projection display device that projects light and displays an image on the surface of the liquid crystal panel, a transparent protective plate is provided on the front surface of the liquid crystal panel, and a foam rubber material is used between the surface other than the image display surface of the liquid crystal panel and the protective plate. A dustproof device for a liquid crystal panel, comprising: enclosing the image display surface with a first packing consisting of: and a space formed by the image display surface, a protective plate, and the first packing consisting of a foam rubber material. 2. A light source (backlight) on the back of a liquid crystal panel.
In a projection display device that projects light and projects an image on the front surface of the liquid crystal panel, a light source (backlight) is provided at a distance on the back surface of the liquid crystal panel, and a first diffusion plate is provided on the back surface of the liquid crystal panel. The back side of the liquid crystal panel is closed, and the second diffusion plate is provided on the projection side of the light source (backlight) to cover the front side of the light source while diffusing the projection light of the light source (backlight). A dustproof device for a liquid crystal panel, characterized in that an optical path from a light source (backlight) formed of a plate and a second diffusion plate is sealed with a second packing made of a foam rubber material. 3. The apparatus according to claim 1, wherein at least the liquid crystal panel and the light source (backlight), the first diffusing plate and the second diffusing plate, and the chassis enclosing the second packing are used for a plurality of vents. A dustproof device for a liquid crystal panel, which is provided with a hole.