JPS62265629A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To improve response characteristics at the time of low temperature and to obtain an excellent picture quality by providing the titled device with a conductive light shielding protection film and a means for supplying a current to the film. CONSTITUTION:Transistors (TRs) 12-14 are formed on a glass substrate 11, a gate insulating film 15 and an amorphous film 16 are formed between electrodes and a picture element electrode 17 is connected to a source electrode 14 so that voltage is applied to liquid crystal by the electrode 17. A light shielding electrode 19 to be the light shielding protection film is formed through an insulating film 18 so that light is not irradiated to the TRs and the gate part 12 of the TR is shielded by the electrode 19.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device with improved operation at low temperatures.

(Prior art) Generally, liquid crystals have narrow temperature characteristics, and especially at low temperatures, the operational response speed of liquid crystals decreases, and when images such as those from television broadcasts are displayed, an afterimage phenomenon occurs or the liquid crystal becomes inoperable. . For this reason, television receivers and the like that use liquid crystals are usually not used at negative temperatures.

Therefore, especially when using at negative temperatures, some methods are being considered to raise the ambient temperature. That is, a conductive mesh such as a mesh screen is provided around the liquid crystal to indirectly warm the liquid crystal.

However, in this case, the mesh may block the light, which may appear on the screen and significantly deteriorate the image quality.

(Problems to be Solved by the Invention) Conventional means for improving the response characteristics of liquid crystals at low temperatures have the drawback of causing deterioration of image quality. In view of these points, it is an object of the present invention to provide a liquid crystal display device that can improve response characteristics at low temperatures and provide good image quality.

[Structure of the invention]

(Means for solving the problem) In the present invention, a light-shielding protective film for shielding light from a transistor that operates a liquid crystal is made conductive, and a means for passing a current through this protective film is provided. It is.

(Function) When the ambient temperature is low, by passing a current through the light-shielding protective film, heat is generated, the liquid crystal is warmed, and the response characteristics of the liquid crystal are improved.

(Example) An example of a liquid crystal display device according to the present invention will be described below based on the drawings.

First, Figure 2 shows a general TP using thin film transistors.
A driving transistor and a scanning section of a T-LCD (thin film transistor liquid crystal display) will be shown, and a simple driving principle of the liquid crystal display will be explained. (1) is a hold circuit, and the video input signal Sv is held for one line by this hold circuit (1)K. (2) is a scanning circuit, which selects one of life (3), (4), (5), and (6) to apply current. Now, if line (3) is selected, transistor (7) becomes conductive due to the torsion. A voltage proportional to the video signal is applied from the signal line (8) to the liquid crystal section (9). The a value is a common electrode to which a constant voltage is applied. Then, the liquid crystal section (9) changes the polarized light beam depending on the voltage of the video signal.

The input light and output light will change.

By the way, the transistor (7) is affected by light.

When strong light is incident, dark current increases. For this reason, the liquid crystal display device is provided with a light shielding means to prevent the transistor (7) from being exposed to light. FIG. 3 is a sectional view showing this transistor section in this embodiment, and the transistor is formed on a glass substrate αυ. here,
α2 is a gate electrode, (1j is a drain electrode, QJJ is a source electrode, and between these electrodes is a gate insulating film (1! 9. Amorphous WX (t (9 is provided respectively. Source electrode α4) K is a pixel electrode αη is connected, and a voltage is applied to the liquid crystal by this electrode αη.In this embodiment, a light-shielding electrode a, which serves as a light-shielding protective film, is provided through an insulating film α to prevent light from hitting the transistor. In other words, this electrode α1 shields the gate portion α of the transistor from light. Note that (A) is also an insulating film.

Next, an embodiment of the overall configuration of a liquid crystal display device according to the present invention will be described with reference to FIG. Qυ, (22 is a glass substrate and 1 are opposed to each other via a spacer (to) and I24. Between the glass substrate (21) and @ are a liquid crystal (c), a color filter (a), and a driving transistor. is arranged,
The pixel electrode (5) of the driving transistor and the color filter (to) form a pair. (to) is the common electrode,
A constant voltage is supplied from the outside. Further, (g) is a light shielding electrode of the driving transistor. The light from the backlight (to) passes through the polarizing plate 01) and the color filter (c) and enters the liquid crystal (c).

The polarization axis of this liquid crystal (c) is changed by the pixel electrode (5) of the transistor, and the light goes out from the other polarizing plate G2 and enters the observer's eyes. By the way, in this embodiment, when the ambient temperature of the liquid crystal display device is low, and therefore the temperature of the liquid crystal part is low, it is possible to flow current through the electrode 4, which is a light-shielding film, and the heat generated thereby warms the liquid crystal. be able to. Therefore, it is possible to improve the response characteristics of the liquid crystal at low temperatures, which has been a problem in the past. Also.

The above electrodes can be provided for each pixel.

Compared to the conventional mesh structure, the image does not deteriorate significantly. It also has good heating efficiency. In addition, in order to avoid affecting the voltage between the common electrode (c) and the pixel electrode (c), the light-shielding electrode is separated from other circuits by 70-
It is desirable to leave it in the

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a liquid crystal display device that can improve the response characteristics of the liquid crystal at low temperatures without significantly deteriorating the image quality.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a liquid crystal display device according to the present invention, and FIG. 2 is a circuit diagram of the device shown in FIG. 1. FIG. 3 is a cross-sectional view of the drive transistor in the device of FIG. 25...Liquid crystal, 27...Pixel electrode. 29...Light shielding electrode. Agent Patent attorney Ken Nori Chika Hiroshi Uji 25--Toshih fM1 diagram] 1 Figure 3, Figure 2I! 1

Claims (1)

[Claims] A liquid crystal display device comprising: a conductive light-shielding protective film for shielding light from a transistor that operates a liquid crystal; and means for applying a current to the protective film.