JP3679428B2 - LCD module - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a so-called liquid crystal module having a liquid crystal cell and backlighting means.
[0002]
[Prior art]
Conventionally, in a so-called liquid crystal module, as disclosed in Japanese Patent Laid-Open No. 4-7519, the liquid crystal cell is housed in a metal frame together with a peripheral drive circuit and a back illumination means to facilitate handling. In such a liquid crystal module, a light source is not disposed directly under the liquid crystal cell as a lighting means on the back, but a light guide plate is disposed on the back of the liquid crystal cell, and a light source is disposed on the side of the light guide plate. Side illumination type lighting means is preferable because the module can be made thin.
[0003]
[Problems to be solved by the invention]
However, in a liquid crystal module having such a side illumination type illumination means, the heat of the light source that is lit is easily accumulated in the module and propagates over time, and is provided on the back surface of the light guide plate accordingly. If the gap between the reflective sheet and the light guide plate is changed or peeled off in some cases, illuminance unevenness occurs, or if it propagates to the liquid crystal cell, it will appear as a decrease in contrast, color change, or whitening. Moreover, this phenomenon does not reach the entire display all at once, but occurs from a part of the display surface and is enlarged, so that it is very noticeable and the display quality is remarkably lowered.
[0004]
Therefore, we considered heat conduction to the metal frame, which is the outer case of the liquid crystal module, to dissipate heat. However, heat is not dissipated only from the metal frame toward the outside, but is also transmitted from the metal frame to the liquid crystal cell. Therefore, although the above-mentioned symptom may be alleviated, it appeared rather in a short time and was inconvenient.
[0005]
[Means for Solving the Problems]
The present invention has been made in consideration of the above points, and a linear light source is disposed in the vicinity of the side surface of the light guide plate disposed on the back surface of the liquid crystal cell and having a reflective sheet on the back surface, and the back surface of the light guide plate. And a resin plate disposed in close contact with the back surface of the metal plate so as to correspond to the central portion of the light guide plate. In the present invention, the linear light source is disposed in the vicinity of the side surface of the light guide plate and is surrounded by the reflection sheet. The linear light source is disposed at least on the back surface of the light guide plate and is part of the outer side of the reflection sheet surrounding the linear light source. A metal plate provided so as to be close to or in contact with only the resin plate, and a resin plate disposed in close contact with the back surface of the metal plate so as to correspond to the central portion of the light guide plate.
[0006]
[Action]
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 reflective sheet and the metal plate.
[0007]
【Example】
1A and 1B are a plan view and a cross-sectional view of a liquid crystal module according to an embodiment of the present invention. Reference numeral 1 denotes a nematic liquid crystal having a structure in which liquid crystal molecules are twisted at 90 to 270 degrees between two substrates 11. A liquid crystal cell having polarizing plates 12 on the front and rear sides. The liquid crystal cell 1 is provided with a driving element 13 for driving liquid crystal around the liquid crystal cell 1 as necessary. The driving element 13 is a so-called TAB supported by a resin film having a foil-like electrode, for example. Although illustrated, the bare chip may be directly connected and fixed to the liquid crystal cell substrate or the drive circuit substrate 14, and both are connected to the peripheral terminals of the liquid crystal cell 1 for driving the liquid crystal, and the common terminal, the power source, etc. May be connected to the drive circuit board 14 that supports the drive elements. As the liquid crystal cell 1, a ferroelectric liquid crystal cell can be used.
[0008]
Reference numeral 2 denotes a light guide plate disposed on the back surface of the liquid crystal cell 1. A light diffusion sheet is provided on the front surface as necessary, and a reflective sheet 21 is provided on the back surface. The light guide plate 2 is used 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 of the light guide plate 2 diffuses light and uniformly illuminates it. It is preferable that unevenness is appropriately provided. The reflective sheet 21 is made of non-mirror-finished aluminum foil or white paper, and may be affixed to the light guide plate 2. Preferably, a slight air layer is formed between the back surface of the light guide plate 2 and the reflective sheet 21. Therefore, it is preferable to increase the reflection / diffusion efficiency. For this purpose, only the peripheral part is preferably attached to the light guide plate 2 or supported by the back resin plate 6 described later.
[0009]
3 is a linear light source arranged in the vicinity of the side surface of the light guide plate 2 and is composed of a fluorescent lamp or a cold cathode tube, and is arranged on two or four sides facing the light guide plate 2 as required. In many cases, one is sufficient. The linear light source 3 is preferably surrounded in a non-contact manner by a reflection sheet 31, and the reflection sheet 31 is made of a substantially cylindrical aluminum foil or the like, and both ends thereof are bonded and fixed to the light guide plate 2. Is efficiently guided to the light guide plate 2.
[0010]
Reference numeral 4 denotes a frame made of a resin molded product, which fixedly stores 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. A buffer material or the like may be used for supporting the liquid crystal cell 1. When these components are fixed by a metal frame 7 to be described later, the frame 4 is not necessary, or the liquid crystal cell 1, the light guide plate 2, and the side-illuminated surface illumination means of the linear light source 3 are separately provided. This frame 4 may be used only for unitization.
[0011]
5 is a metal plate arranged on the back surface of the light guide plate 2 so as not to contact the linear light source 3, and is made of an aluminum plate or iron plate having a thickness of 0.01 to 1.0 mm, and does not contact the linear light source 3. This is because the heat is not directly received. The purpose of the metal plate 5 is to spread the transmitted heat substantially uniformly, hold down the reflection sheets 21 and 31, that is, reduce the brightness unevenness, and protect the reflection sheet 21. You may provide so that it may adjoin to or contact | abut only a part of the outer side of the reflective sheet 31 which is arrange | positioned on the back surface of the optical plate 2, and surrounds the linear light source 3. FIG.
[0012]
6 is a resin plate made of an insulating material having heat resistance and heat conductivity, such as polyethylene terephthalate, and is disposed on the back surface of the metal plate 5 so as to correspond to the central portion of the light guide plate. Is used to protect the reflective sheet 21 and the metal plate 5 from being damaged. When the metal plate 5 is exposed to the entire surface, the heat is radiated and the temperature is not uniformed. Also plays the role of making it constant.
[0013]
A metal frame 7 accommodates the liquid crystal cell 1, the light guide plate 2 and the like integrally. The metal frame 7 has a through-hole for observing the surface of the liquid crystal cell in the center, and the state of being fixed to the frame body 4 with a claw caulking is illustrated but is not limited thereto. May be.
[0014]
With such a configuration, for example, the liquid crystal module is turned on at room temperature, and after 15 to 60 minutes have elapsed, the entire state of the liquid crystal display surface is observed, and the contrast on the liquid crystal display surface and the lighting and non-lighting locations are also observed. When the light transmittance of the pixel was measured at the center and the periphery of the screen, respectively, when only the resin plate was used, after 15 minutes, the contrast had already been reduced or whitened in part of the screen. In the embodiment of the invention, even after 60 minutes, a change in the light transmittance of the entire screen was recognized, but the contrast was such that the observer felt uncomfortable or the screen was unbalanced. There was no change in color.
[0015]
【The invention's effect】
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 reflective sheet and the metal plate. And illuminance unevenness, a decrease in contrast of the liquid crystal display, a color change, or whitening is hardly observed. Such a phenomenon occurs from a part of the display surface and is enlarged, so that the display quality is extremely noticeable and the display quality is remarkably lowered, but the display quality can be kept high.
[Brief description of the drawings]
1A is a plan view of a liquid crystal module according to an embodiment of the present invention, and FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Liquid crystal cell 2 Light guide plate 21 Reflection sheet 3 Linear light source 31 Reflection sheet 5 Metal plate 6 Resin plate

Claims (2)

A liquid crystal cell, a light guide plate disposed on the back surface of the liquid crystal cell and having a reflective sheet on the back surface, a linear light source disposed close to the side surface of the light guide plate, and a linear light source on the back surface of the light guide plate so as not to contact A liquid crystal module comprising: a metal plate disposed on the back of the metal plate; and a resin plate disposed in close contact with the back surface of the metal plate so as to correspond to a central portion of the light guide plate. A liquid crystal cell, a light guide plate disposed on the back surface of the liquid crystal cell and having a reflection sheet on the back surface, a linear light source disposed close to the side surface of the light guide plate and surrounded by the reflection sheet, and disposed at least on the back surface of the light guide plate a metal plate disposed so as to close or abut only a part of the outside of the reflection sheet surrounding the linear light source while being are closely arranged on the rear surface of the metal plate so as to correspond to the central portion of the light guide plate A liquid crystal module comprising a resin plate.

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