Liquid crystal cells – elements and systems – Particular excitation of liquid crystal – Electrical excitation of liquid crystal
Patent
1997-08-22
1999-10-05
Sikes, William L.
Liquid crystal cells, elements and systems
Particular excitation of liquid crystal
Electrical excitation of liquid crystal
349187, 349 49, 349 50, 349 41, 349122, G02F 11333, G02F 1136, G02F 113
Patent
active
059632798
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a monochrome or colored liquid crystal display device which is widely used for watches, calculators, video cameras, and various other electronic devices and a method of producing the same.
Particularly, the invention relates to a structure of a liquid crystal display device for driving liquid crystal by controlling a thin film diode or a thin film transistor serving as a nonlinear element provided for each picture-element disposed in a matrix shape on a display screen and a method of producing the same.
BACKGROUND TECHNOLOGY
The display capacity of liquid crystal display devices using a liquid crystal panel has been recently increased.
In a simple matrix structured liquid crystal display device employing a multiplex driving system, the contrast drops or the response speed reduces as a time-shared system is further developed. Accordingly, if the liquid crystal display device 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 picture-element to remove such drawbacks.
In the active matrix system liquid crystal panel, there are two types: one is a three terminal system employing thin film transistors (hereinafter referred to as "TFT") serving as switching elements and the other is a two terminal system employing thin film diodes (hereinafter referred to as "TFD") serving as nonlinear resistors. The two terminal system is superior to the three terminal system since the former is simple in structure and easier to produce.
A diode type, a varsity type, and an MIM (Metal-Insulator-Metal) type have been developed as the two terminal system.
The structure of a liquid crystal display device employing conventional thin film diodes will be now described with reference to FIG. 20 which is a plan view showing a part thereof and FIG. 21 which is a cross sectional view taken along the line A--A in FIG. 20.
The liquid crystal display device comprises, as shown in FIG. 21, a first substrate 1 and a second substrate 2 respectively made of a transparent material such as glass, wherein the first and second substrates 1 and 2 oppose each other with a certain gap via a spacer 3 and a liquid crystal 4 is filled in between the first and second substrates 1 and 2.
A lower electrode 5 and a picture-element electrode (display electrode) 6 are disposed on the first substrate 1 in a matrix shape as shown in FIG. 20, and an anodic oxidation layer 7 as a nonlinear resistor layer is formed on the lower electrode 5. Further, a pair of upper electrodes 8 and 9 are disposed on the anodic oxidation layer 7 so as to overlap each other.
A thin film diode (TFD) 11 as a first nonlinear resistor element is structured by the lower electrode 5, the anodic oxidation layer 7 and the upper electrode 8, and a TFD 12 as a second nonlinear resistor element is structured by the lower electrode 5, the anodic oxidation layer 7 and the upper electrode 9.
The upper electrode 8 of the first TFD 11 is connected with a signal electrode 13 (FIG. 20) which applies a signal from the outside to the TFD 11, and the upper electrode 9 of the second TFD 12 is connected to the picture-element electrode 6.
A switching element part is structured by the first TFD 11 and the second TFD 12, and an electric path is formed in the order of: "the signal electrode 13.fwdarw. the upper electrode 8.fwdarw. the anodic oxidation layer 7.fwdarw. the lower electrode 5.fwdarw. the anodic oxidation layer 7.fwdarw. the upper electrode 9.fwdarw. the picture-element electrode 6".
On the other hand, a black matrix 14 is provided on the surface of the second substrate 2 opposing the first substrate 1 at an entire region thereof as hatched in FIG. 20 for preventing leaking of light from a gap between each picture-element electrode 6 disposed on the first substrate 1. That is, the black matrix 14 is provided on a non-display part for intercepting light.
Further, an opposing electrode 15 formed as a scanning elec
REFERENCES:
patent: 5648826 (1997-07-01), Song et al.
patent: 5684547 (1997-11-01), Park et al.
patent: 5808595 (1998-09-01), Kubota et al.
patent: 5861928 (1999-01-01), Sekiguchi
patent: 5893621 (1999-04-01), Sekiguchi
Citizen Watch Co. Ltd.
Horney Kari M.
Sikes William L.
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