Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Electrical excitation of liquid crystal
Patent
1997-01-17
1999-01-19
Sikes, William L.
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Electrical excitation of liquid crystal
349 44, 349110, 349106, 349111, G02F 1136, G02F 1135, G02F 11333
Patent
active
058619283
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a monochrome or color liquid crystal display system which has been widely employed as a display system of a watch, a pocket calculator, a video camera, and a variety of electronic devices. Particularly, it relates to a liquid crystal display system having first and second electrodes which are disposed on one of two substrates between which a liquid crystal is filled, and also having a nonlinear resistor having a structure of a "metal-insulating film-metal" or a "metal-insulating film-transparent conductive film" between the first and second electrodes.
BACKGROUND TECHNOLOGY
A display capacity of a liquid crystal display system using a liquid crystal panel has been recently increased.
In a simple matrix structured liquid crystal display system employing a multiplex driving system, a contrast is dropped or a response speed is reduced as a duty ratio is higher. Accordingly, if the liquid crystal display system has about 200 scanning lines, it is difficult to obtain a sufficient contrast.
Accordingly, there has been employed an active matrix system liquid crystal panel having switching elements in each pixel to remove such drawbacks.
There are two types of active matrix system liquid crystal display panel, namely, one is a three terminal devices employing thin film transistors as switching elements and the other is two terminal devices employing nonlinear resistors. The two terminal devices is superior to the three terminal devices since the former is simple in structure and a method of manufacturing thereof.
A diode type, a varistor type, or an MIM (Metal-Insulator-Metal) type is developed as the two terminal devices.
Among these types, the MIM type is simple in structure and has few manufacturing steps.
Further, the liquid crystal panel requires high density and high definition, and the switching elements require reduction of their occupied areas.
As a means for achieving high density and high definition, there are a photo-lithography technique and an etching technique which are respectively micro processing techniques of a semiconductor production technique. However, even if this semiconductor production technique is employed, it is very difficult to realize a large area with low cost.
A structure of a switching element which efficiently makes the area large with low cost will be now described with reference to FIG. 11, showing a plan view exemplifying a conventional liquid crystal display system, and FIG. 12 showing a cross sectional view taken along the line XII--XII of FIG. 11.
The liquid crystal display system comprises, as shown in FIG. 12, a first substrate 131, a second substrate 136 which are respectively made of a transparent material and opposing each other by way of a spacer 142 at a given gap, and a liquid crystal 141 which is filled between the first and second substrates 131 and 136.
A first electrode 132 and a display electrode 135 are respectively arranged in a matrix on the first substrate 131 as shown in FIG. 11, and a nonlinear resistor layer 133 is disposed on the first electrode 132. Further, a second electrode 134 is disposed on the nonlinear resistor layer 133 to overlap the nonlinear resistor layer 133 so as to constitute a nonlinear resistor 130. The second electrode 134 extends from the display electrode 135 and a part thereof serves as a display electrode as shown in FIG. 11.
A black matrix 137 is disposed at an entire region as hatched in FIG. 11 on a surface of the second substrate 136 opposing the first substrate 131 so as to prevent leaking light from the gaps between each display electrode 135 disposed on the first substrate 131. That is, the black matrix 137 is disposed on a non-display electrode portion as a shading portion.
Still further, an opposed electrode 139 is disposed on the second substrate 136 opposing the display electrode 135 by way of an insulating film 138 as shown in FIG. 12, and it is arranged in a belt-shape as shown in FIG. 11 so that the opposed electrode 139 is prevented from contacting the black matri
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Citizen Watch Co. Ltd.
Sikes William L.
Ton Toan
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