Liquid crystal display element and method for treating defective pixels therein
AssigneeHosiden Corporation
InventorsYasuhiro Ukai, Tomihisa Sunata, Teizou Yukawa
Life of this patent
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Abstract
In an active liquid crystal display element which operates in a normally white mode, there is formed a shorting metal layer which overlaps each pixel electrode and a source bus adjacent thereto. In those portions of the pixel electrode and the source bus overlapping the shorting metal layer there are formed weld metal layers. The pixel electrode of a defective pixel is connected to the corresponding source bus by welding the weld metal layers and the shorting metal layer through irradiation with laser beams to the above-mentioned overlapping portions. As a result of this, the defective pixel becomes a black defect when the liquid crystal display element operates.
Claims17
A liquid crystal display element which operates in a normally white mode and wherein a plurality of source buses and a plurality of gate buses are arranged in rows and columns at right angles to each other on the inside of a first transparent base plate, pixel electrodes are each disposed in an area defined by said source and gate buses and connected via a thin film transistor to a pair of adjoining ones of said source and gate buses, and a common electrode is formed substantially all over the inside of a second transparent base plate in opposed relation to said pixel electrodes, liquid crystal being interposed between said base plates, said liquid crystal display element including:
- a shorting metal layer formed in a manner to overlap a marginal portion of each of said pixel electrodes and a portion of an adjoining one of said source buses with an insulating layer being interposed therebetween;
- and
- a fused metal portion formed by laser welding through said insulating layer between said overlapping portions of each defective pixel and the adjoining one of said source buses, said pixel electrode of said each defective pixel being electrically connected to said source bus through said fused metal portion.
A liquid crystal display element which operates in a normally white mode and wherein a plurality of source buses and a plurality of gate buses are arranged in rows and columns at right angles to each other on the inside of a first transparent base plate, pixel electrodes are each disposed in an area defined by said source and gate buses and connected via a thin film transistor to a pair of adjoining ones of said source and gate buses, and a common electrode is formed substantially all over the inside of a second transparent base plate in opposed relation to said pixel electrodes with liquid crystal interposed therebetween, each of said pixel electrodes being formed by a transparent conductive layer on an insulating layer, together with the corresponding one of said source buses, said liquid crystal display element including:
- a capacitive bus formed in a manner to overlap said pixel electrodes of each row with said insulating layer interposed therebetween;
- a first weld metal layer formed opposite said pixel electrode with said insulating layer interposed therebetween, said first weld metal layer being connected to said capacitive bus;
- a second weld metal layer overlapping said first weld metal layer with said insulating layer interposed therebetween, at least one portion of said second weld metal layer being formed directly on said pixel electrode;
- and
- a fused metal portion formed by laser welding on said overlapping portion of each defective pixel, for connecting said pixel electrode of said defective pixel to said capacitive bus capacitance.
A method for disposing of a defective pixel in a liquid crystal display element which operates in a normally white mode and wherein a plurality of parallel source buses and a plurality of parallel gate buses are arranged in rows and columns at right angles to each other on the inside of a first transparent base plate, pixel electrodes are each disposed in an area defined by said source and gate buses and connected via a thin film transistor to a pair of adjoining ones of said source and gate buses, and a common electrode is formed substantially all over the inside of a second transparent base plate in opposed relation to said pixel electrodes with liquid crystal interposed therebetween, said method including:
- welding, by irradiation with laser beams from the outside, those portions of a shorting metal layer which overlap a marginal portion of said pixel electrode and an adjoining one of said source buses with an insulating layer interposed therebetween, to connect said pixel electrode of each defective pixel to the corresponding one of said source buses which is to be supplied with a potential different from that applied to said common electrode, whereby the nature of the defect of said defective pixel is changed.
Dependencies are inferred from the claim text.