JPH07318936A - Liquid crystal module - Google Patents

Abstract

PURPOSE:To prevent the deformation and peeling of a reflecting sheet and to prevent the uneven luminance and degradation of contrast in a liquid crystal display by disposing a metal plate on the rear surface of a light guide plate so that the metal plate does not come into contact with a linear light source and disposing a resin plate on the rear surface of the metal plate. CONSTITUTION:The light guide plate 2 is disposed on the rear surface of the liquid crystal cell 1 and has a reflecting sheet 21 on its rear surface. The linear light source 3 is surrounded by a reflecting sheet 31 which does not come into contact with the light source 3. The metal plate 5 consists of an aluminum or iron plate and is disposed on the rear surface of the light guide plate 2 so that the metal plate does not come into contact with the linear light source 3. The resin plate 6 consists of an insulating material having heat resistance and thermal conductivity and is disposed on the rear surface of the metal plate 5 corresponding to the center part of the light guide plate 2. Thereby, heat from the linear light source 3 is not directly given to the metal plate 5 but the transmitted heat can be uniformly diffuse. The resin plate 6 assists the effect of uniformizing heat distribution and protects the reflecting sheet 21 and the metal plate 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called liquid crystal module having a liquid crystal cell and back lighting means.

[0002]

2. Description of the Related Art Conventionally, in a so-called liquid crystal module, as shown in Japanese Patent Laid-Open No. 4-7519, a liquid crystal cell is housed in a metal frame together with a peripheral drive circuit and a lighting means on the back surface for easy handling. It was In such a liquid crystal module, the light source is not disposed directly below the liquid crystal cell as the illumination means on the rear surface, but the light guide plate is disposed on the rear surface of the liquid crystal cell, and the light source is disposed on the side surface of the light guide plate.
A so-called side illumination type illumination means is preferable because the module can be made thin.

[0003]

However, in the liquid crystal module having the side illumination type illumination means as described above,
The heat of the light source that has been turned on easily accumulates in the module and propagates with the passage of time, which causes the gap between the reflection sheet and the light guide plate provided on the back surface of the light guide plate to change, and in some cases peeling occurs. When the illuminance becomes uneven, or when it propagates to the liquid crystal cell, it appears as a decrease in contrast, a change in color, or whitening. Moreover, this phenomenon does not extend to the entire display all at once, but occurs from a part of the display surface and is magnified, so that the display quality is extremely noticeable and the display quality is significantly deteriorated.

Therefore, it is considered to conduct heat to a metal frame which is an outer case of the liquid crystal module to dissipate the heat. However, the heat is not dissipated only from the metal frame to the outside but the heat is also transferred from the metal frame to the liquid crystal cell. Since it was transmitted, the above-mentioned symptoms were sometimes alleviated, but rather it appeared in a short time and was inconvenient.

[0005]

The present invention has been made in view of the above points, and a linear light source is provided near a side surface of a liquid crystal cell and a light guide plate having a reflection sheet on the back surface. The metal plate is disposed on the back surface of the light guide plate so as not to come into contact with the linear light source, and the resin plate is provided on the back surface of the metal plate so as to correspond to the central portion of the light guide plate. Further, according to the present invention, the linear light source is arranged close to the side surface of the light guide plate and surrounded by the reflection sheet, and is arranged at least on the back surface of the light guide plate, and only a part of the outside of the reflection sheet surrounding the linear light source. And a resin plate disposed on the back surface of the metal plate so as to correspond to the central portion of the light guide plate.

[0006]

As a result, the metal plate uniformly diffuses the propagated heat without directly receiving the heat of the linear light source, and the resin plate assists the soaking action and protects the reflection sheet and the metal plate.

[0007]

1A and 1B are a plan view and a sectional view of an essential part of a liquid crystal module according to an embodiment of the present invention, in which 1 has a structure in which liquid crystal molecules are twisted at 90 to 270 degrees between two substrates 11. It is a liquid crystal cell that is filled with nematic liquid crystal and has polarizing plates 12 in front and behind. The liquid crystal cell 1 is provided with a driving element 13 for driving a liquid crystal, which is connected to the periphery of the liquid crystal cell 1 if necessary. The driving element 13 is, for example, a so-called TAB supported by a resin film having a foil electrode. Although illustrated, the bare chip may be directly connected and fixed to the liquid crystal cell substrate or the drive circuit substrate 14, both of which are connected to the peripheral terminals of the liquid crystal cell 1 to drive the liquid crystal, and the common terminal, the power source, etc. May be connected to the drive circuit board 14 that supports the drive element. The liquid crystal cell 1 may be a ferroelectric liquid crystal cell or the like.

Reference numeral 2 denotes a light guide plate arranged on the back surface of the liquid crystal cell 1, which has a light diffusion sheet 21 on the front surface and a reflection sheet 21 on the back surface as necessary. The light guide plate 2 is formed by laminating one or a plurality of flat plates having excellent light transmission characteristics such as an acrylic resin flat plate, and the back surface thereof is a spotted printing paint for diffusing light and illuminating it uniformly. It is preferable that irregularities are appropriately provided.
The reflection sheet 21 is made of non-mirror-finished aluminum foil, white paper, or the like and may be attached to the light guide plate 2. However, a slight air layer is preferably formed between the back surface of the light guide plate 2 and the reflection sheet 21. Therefore, it is preferable to improve the reflection / diffusion efficiency. For this purpose, it is preferable that only the peripheral portion is attached to the light guide plate 2 or supported by the backside resin plate 6 described later.

Reference numeral 3 denotes a linear light source which is arranged close to the side surface of the light guide plate 2 and is composed of a fluorescent lamp or a cold cathode tube, and is provided on two or four opposite sides of the light guide plate 2 as required. It is arranged, but in most cases, only one is required. This linear light source 3 is preferably surrounded by a reflection sheet 31 in a non-contact manner, and the reflection sheet 31 is made of a substantially cylindrical aluminum foil or the like. Is efficiently guided to the light guide plate 2.

Reference numeral 4 denotes a frame body made of a resin molded product or the like, which fixedly accommodates the light guide plate 2, the linear light source 3, or the lead wire 32 of the linear light source, and further supports the liquid crystal cell 1.
When supporting the liquid crystal cell 1, a cushioning material 41 or the like may be used. Further, when fixing these components by a metal frame 7 described later, the frame body 4 is not necessary, or the liquid crystal cell 1, the light guide plate 2 and the side surface illumination type surface illumination means of the linear light source 3 are separately provided. The frame body 4 may be used only for unitization.

A metal plate 5 is arranged on the back surface of the light guide plate 2 so as not to come into contact with the linear light source 3, and has a thickness of 0.01 to 1.0.
The linear light source 3 does not come into contact with the linear light source 3 because it does not receive the heat directly. The purpose of the metal plate 5 is to spread the propagated heat substantially uniformly, to suppress the reflection sheets 21 and 31, that is, to reduce the uneven brightness, and to protect the reflection sheet 21. It may be provided so as to approach or contact only a part of the outer side of the reflection sheet 31 that is arranged on the back surface of the light plate 2 and surrounds the linear light source 3.

Reference numeral 6 denotes a resin plate made of an insulating material having heat resistance and thermal conductivity such as polyethylene terephthalate, which is arranged on the back surface of the metal plate 5 so as to correspond to the central portion of the light guide plate. The insulation of the reflective sheet 21
It is used for the purpose of protecting the metal plate 5 from being damaged, and when the entire surface of the metal plate 5 is exposed, a large amount of heat is dissipated and the temperature does not become uniform, so that it also serves to make the heat diffusion and heat dissipation by the metal plate 5 constant.

Reference numeral 7 is a metal frame for accommodating the liquid crystal cell 1, the light guide plate 2 and the like as a unit. The metal frame 7 has a through hole in the center for observing the surface of the liquid crystal cell, and the frame 4
Although a state in which the nails are fixed by caulking is shown in the figure, the present invention is not limited to this and may be fixed with a screw, for example.

With such a structure, for example, after the liquid crystal module is turned on at room temperature and 15 to 60 minutes have passed, the entire state of the liquid crystal display surface is observed, and the contrast on the liquid crystal display surface and the lighting portion are not observed. The light transmittance of the pixel at the lighting portion was measured at the center and the peripheral portion of the screen, respectively, and when only the resin plate was used, after 15 minutes, the contrast was already reduced or whitening had occurred on a part of the screen. But,
In the embodiment of the present invention, a change in the light transmittance of the entire screen was observed even after 60 minutes had passed, but the observer felt uncomfortable in a local area of the screen or a screen unbalance was felt. No change in contrast or coloration occurred.

[0015]

As a result, the metal plate evenly diffuses the propagated heat without directly receiving the heat of the linear light source, and the resin plate assists the soaking action and protects the reflection sheet and the metal plate. The deformation and peeling of the reflection sheet were less likely to occur, and uneven illuminance, lowering of contrast in liquid crystal display, color change, or whitening became extremely difficult to appear. Since such a phenomenon occurs from a part of the display surface and is magnified, it is very noticeable and the display quality is remarkably lowered, but the display quality can be kept high.

[Brief description of drawings]

FIG. 1 is a plan view a and A of a liquid crystal module according to an embodiment of the present invention.
-A sectional view b.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal cell 2 Light guide plate 21 Reflective sheet 3 Linear light source 31 Reflective sheet 5 Metal plate 6 Resin plate

Claims (2)

[Claims] 1. A liquid crystal cell, a light guide plate arranged on the back surface of the liquid crystal cell and having a reflection sheet on the back surface, a linear light source arranged near the side surface of the light guide plate, and a linear shape on the back surface of the light guide plate. A liquid crystal module comprising: a metal plate arranged so as not to contact the light source; and a resin plate arranged on the back surface of the metal plate so as to correspond to the central portion of the light guide plate. 2. A liquid crystal cell, a light guide plate arranged on the back surface of the liquid crystal cell and having a reflection sheet on the back surface, a linear light source arranged close to the side surface of the light guide plate and surrounded by the reflection sheet, and at least a conductor. A metal plate arranged on the back surface of the light plate so as to come close to or abut only a part of the outside of the reflection sheet surrounding the linear light source, and on the back surface of the metal plate so as to correspond to the central portion of the light guide plate. A liquid crystal module, comprising: