JPH0324527A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To preclude a spot defect and make only part of a picture element absent even if a two-terminal element is broken by dividing each picture element into several and driving respective parts by individual two-terminal elements. CONSTITUTION:One picture element electrode 2 is divided into 2 - 10 parts, which are each provided with a two-terminal element. For example, two picture element electrodes each on both sides of a driving electrode 3, i.e. four electrodes in total are provided on a substrate to form one picture element, and the respective picture element electrodes are formed by depositing, for example, I.T.O., etc., by a sputtering method and etching it selectively. There fore, even if an element defect occurs, 3/4 of one picture element is driven normally to prevet a remarkable decrease in display quality. Consequently, the liquid crystal display device which does not have a picture element defect even if a two-terminal element becomes defecive is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display device using a two-terminal element, such as a display panel for a measuring instrument, an image display device for a personal computer, and a liquid crystal television.

(Summary of the Invention) The present invention provides a liquid crystal display device using a two-terminal element in which a non-linear resistance film is provided between a pixel electrode and a driving electrode, in which a pixel electrode is divided into 2 to 1000000 parts, and each divided pixel electrode is By forming a two-terminal element, even if a two-terminal element becomes defective (such as an open circuit), the entire pixel does not become defective, but only a portion of the pixel becomes defective.

This improves display quality and yield in liquid crystal display devices. (Conventional technology) Small size. Lightweight and thin. Liquid crystal display devices have an advantage over other display devices as display devices with low power consumption, and have been put into practical use in recent years. ? li. In order to increase the amount of information displayed on crystal display devices, three-terminal active matrix liquid crystal display devices such as thin film transistors, so-called MIMs consisting of Zn○ varistors and metal-insulating film-metal structures have been developed.
Two-terminal active matrix liquid crystal display devices, such as nonlinear resistive elements and nonlinear resistive elements using Si-rich nitride or oxide films in the insulating film portion, are being researched. Compared to three-terminal elements, two-terminal elements have the advantage of having fewer layers and relatively coarse patterning accuracy, making them low-cost. Application to large area display devices is possible.

FIG. 4 is an X-Y matrix panel circuit diagram of a two-terminal active matrix liquid crystal display device using nonlinear resistance elements. Usually, about 100 to 1000 row liquid crystal drive electrodes and column liquid crystal drive electrodes are formed on each of the substrate and the counter substrate. A liquid crystal 33 and a nonlinear resistance element 34 are formed at the xy intersection. FIG. 3 [al and ridges] are a front view and a side view, respectively, of a two-terminal element using a 3i silicon nitride film or the like as a nonlinear resistance element.

After selectively forming a pixel electrode 22 (1.T.O.) on a transparent substrate, a nonlinear resistance film 24 (silicon nitride) and a drive electrode 23 (Cr) are deposited, and each is selectively etched. It has become. Driving of such a liquid crystal display device is performed as follows.

A large number of row electrodes 31 in FIG. 4 are selected line-by-line from the top one by one, and data is written using the column electrodes 32 within the selection period. In order to display with sufficient contrast at this time, the effective voltage applied to the liquid crystal at the selected point must be greater than the liquid crystal's saturation voltage, and the effective voltage applied to the liquid crystal at non-selected points must be higher than the liquid crystal's saturation voltage. It needs to be smaller than the threshold voltage. When a nonlinear resistance film is used, the resistance of the nonlinear resistance film 24 becomes low at the selection point during writing (when high voltage is applied), and charges are easily injected into the liquid crystal 33.
During the holding period (when low voltage is applied), the nonlinear resistance Wl! 24
The resistance of the liquid crystal 33 increases, and the charges injected into the liquid crystal 33 are more likely to be retained. In this way, the effective voltage applied to the liquid crystal 33 can be kept high. In addition, when not selected, the resistance of the nonlinear resistance film 24 does not decrease so much during writing, and the resistance of the liquid crystal 3
3, not much charge is injected into it. Therefore, the effective voltage applied to the liquid crystal 33 can be kept relatively low, and high contrast can be maintained even if the number of divisions is considerably increased. In the nonlinear resistance element, the &lI rule and structure of the nonlinear resistance film are determined so that the nonlinear resistance film has a desired resistance value during each of the writing period and the holding period. Furthermore, in order to obtain a sufficient drive margin when displaying with such a liquid crystal display device, the ratio between the capacitance CLC of the liquid crystal section and the capacitance CI of the nonlinear resistance element section in each pixel must be made sufficiently large. is also necessary. (At least CLC/C
I≧5) [Problem to be solved by the invention] In this way, in a liquid crystal display device using a nonlinear resistance element,
Although it is possible to increase the display capacity, pixel defects occur due to defects during SiNX film formation, etching defects during patterning, electrostatic damage, and the like. In the conventional structure, one two-terminal element
If one pixel is broken, one pixel becomes a point defect, but the present invention provides a liquid crystal display device in which even if a two-terminal element breaks, it does not become a point defect and only a part of the pixel is chipped.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention divides one pixel electrode into 2 to 10 parts and provides a two-terminal element in each of them. Even if a defect occurs, it does not become an M-element defect and only a portion of the pixel is missing. [Examples] Examples of the present invention will be described below based on the drawings. 1st
Figures (al and (bl) and Figure 2+a+. (bl is a diagram showing the two-terminal element of the present invention. In Figure 1, there are four terminals in total, two on each side of the drive electrode 3 on the substrate 1. 1 pixel.Each pixel electrode is, for example, 16T.○,
The material can be deposited by the Subanok method, etc., and then selectively etched. Next, the nonlinear resistive film 4
(for example, Si 3iNx) and drive electrode 3 (
For example, Cr) is continuously deposited in this order and etched continuously in one mask step.

The reason why a two-terminal element becomes defective is that the nonlinear resistive film T
! i. Defects in the membrane due to roughness of the base at the time of membrane, adhesion of rubber, etc.
Defects such as etching of necessary parts of the drive electrode 3, pixel electrode 2, and nonlinear resistive film 4 due to dust adhesion on the substrate, resist bubbles, resist scratches, mask scratches, etc. during patterning, destruction due to static electricity during the liquid crystal panel manufacturing process, etc. is possible.

By dividing one pixel into four in this way, even if an element defect occurs, 374 out of 1 pixels can be driven normally, and a significant deterioration in display quality can be prevented.

FIG. 2 shows an example in which one pixel is divided into two.

〔Effect of the invention〕

As described above, according to the present invention, the display quality and yield of a liquid crystal panel can be improved simply by changing the shape of the mask without improving the process environment (cleanliness, static electricity).

3,23・ 4 24・ 31・・・・ 32・・・・ 33・・・・ 34・・ Drive electrode nonlinear resistive film Row liquid crystal drive electrode Column liquid crystal drive electrode liquid crystal nonlinear resistance element

[Brief explanation of drawings]

FIG. 1 (al and (b) are a plan view and a sectional view, respectively, showing a first embodiment of the present invention, and FIG. 2 (al and (bl) are a plan view and a sectional view, respectively, showing a second embodiment of the present invention. , Fig. 3 tag.

Claims (1)

[Claims] In a liquid crystal display device that has multiple pixel electrodes on a transparent substrate and uses a two-terminal element consisting of a nonlinear resistive film and a driving electrode, each pixel is divided into 2 to 10 parts, each of which is driven by a separate two-terminal element. A liquid crystal display device characterized by: