JPH03210534A - Two-terminal element - Google Patents

Abstract

PURPOSE:To prevent the formation of spot defects in a liquid crystal panel even if electrodes for driving are partly disconnected by wiring the driving electrodes like rings and feeding electricity to nonlinear type resistance films from both sides. CONSTITUTION:Plural pieces of picture element electrodes 2 are formed on a substrate 1 and the nonlinear resistance films 4 and the driving electrodes 3 are continuously deposited in this order and are continuously etched in one time of mask stage. The electrodes 3 for driving are wired like rings from both sides to the two-terminal element parts of the picture element electrodes 2. The electricity is fed from the nonlinear resistance films 4, by which the line disconnection is prevented even if one side of the driving electrodes 3 is disconnected. The generation of the spot defects of the liquid crystal panel is lessened simply by changing the shape of a mask in this way without increasing the number of process. The yield is thus improved.

Description

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

[Summary of the invention]

The present invention is a two-terminal element in which a nonlinear resistance film is provided between a pixel electrode and a drive electrode, and the drive electrode is wired in a ring shape, and power is supplied to the nonlinear resistance film from both sides. The purpose is to improve yield by preventing pixel defects from occurring even if there is a disconnection in the secondary electrode or due to poor patterning, etc., as long as both sides are not disconnected.

[Conventional technology]

Liquid crystal display devices have advantages over other display devices as small, lightweight, thin, and low power consumption display devices, and have been put into practical use in recent years. In order to increase the amount of information displayed on liquid crystal display devices, three-terminal active matrix liquid crystal display devices such as thin film transistors, so-called MIM type nonlinear resistance elements such as ZnO varistors and metal-insulating film-metal structures, and Si in the insulating film part are used. Two-terminal active matrix liquid crystal display devices such as nonlinear resistive elements using rich nitride or oxide films are being studied.

Compared to three-terminal devices, two-terminal devices have the characteristics that the number of formed films is smaller and the patterning precision can be considerably rougher, so that they can be applied to low-cost, large-area display devices.

FIG. 3 is an X-Y matrix panel circuit diagram of a two-terminal active matrix liquid crystal display device using nonlinear resistance elements. Generally, 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 X-Y intersection. FIG. 2 is a front view and a side view of a two-terminal element using a Si-rich 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. 3 are selected one by one from the top, 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 a high voltage is applied), and charges are easily injected into the liquid crystal 33, which increases the resistance during the retention period (when a low voltage is applied). , the resistance of the nonlinear resistive film 24 increases,
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 nonlinear resistive film 2 is
The resistance of 4 is not so low that not much charge is injected into the liquid crystal 33. 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 composition 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.

In addition, in order to obtain a sufficient drive margin when displaying with such a liquid crystal display device, the capacitance CLC of the liquid crystal section and the capacitance C of the nonlinear resistance element section in each pixel must be
It is also necessary to make the ratio with I sufficiently large. (At least CLC/CI≧5) [Problem to be solved by the invention] In this way, in a liquid crystal display device using a nonlinear resistance element,
Disconnection is likely to occur at the stepped portion of the drive electrode formed by the pixel electrode, which is one of the causes of lower yield. Further, since the patterning accuracy can be quite rough, it is possible to increase the capacity of the display, but the driving electrodes may be disconnected due to dust adhesion, resist bubbles, resist scratches, etc. during patterning.

Therefore, the present invention provides a two-terminal element that does not cause a point defect in a liquid crystal panel even if a portion of the driving electrode is disconnected.

[Means to solve the problem]

In order to solve the above problems, the present invention wires the drive electrode in a ring shape in the two-terminal element of each pixel and supplies power to the nonlinear resistance film from both sides, so that one side of the drive electrode is disconnected. This also prevents line breakage.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. FIG. 1 is a diagram showing a two-terminal element of the present invention.

In FIG. 1, a plurality of pixel electrodes 2 are formed on a substrate 1. For example, 1. T.O.

It can be formed by depositing such as by sputtering method or the like and selectively etching it. Next, the nonlinear resistive film 4
(for example, Si-rich 5iNx) and the driving electrode 3 (for example, Cr) are successively deposited in this order and successively etched using - times of masking steps. At this time, the driving electrode 3 is wired in a ring shape from both sides to the two-terminal element portion of the pixel electrode 2.

A difference is created in the overlapping part of the pixel electrode 2 and the drive electrode 3, and the film thickness of the drive electrode 3 becomes thinner at that part, resulting in a disconnection and a point defect. By layering the wiring, even if one side is disconnected, it will not become a point defect as long as the driving electrode 3 on the opposite side is conductive.

Further, if a necessary part of the driving electrode 3 is etched due to dust adhesion on the substrate, resist bubbles, resist scratches, mask scratches, etc. during patterning, it will also become a point defect, but if only one side is broken, it will not be a point defect.

〔Effect of the invention〕

As explained above, according to the present invention, the occurrence of point defects in liquid crystal panels can be reduced by simply changing the shape of the mask without increasing the number of steps, and the yield can be improved.

[Brief explanation of drawings]

Figure 1 is a diagram showing the two-terminal element of the present invention, and Figure 1 (a)
is a plan view, FIG. 1(b) is a sectional view, FIG. 2 is a diagram showing a conventional two-terminal element, FIG.
) is a sectional view, and the third figure is an XY matrix panel circuit diagram of a two-terminal active matrix liquid crystal display device using nonlinear resistance elements. 1, 21 ・ 2, 22 ・ 3, 23 ・ 4, 24 φ 31 φ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・41 ・Column liquid crystal driving electrode ・Liquid crystal ・Nonlinear resistance element

Claims (1)

[Claims] A two-terminal element having a plurality of pixel electrodes on a transparent substrate, a nonlinear resistance film, and a drive electrode, characterized in that the drive electrode is wired in a ring shape for each pixel. .