Active matrix display device

• US 5,434,686 A
• Filed: 09/09/1993
• Issued: 07/18/1995
• Est. Priority Date: 05/08/1991
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Imaya, Akihiko, Kato, Hiroaki, Kanemori, Yuzuru, Irie, Katsumi, Yano, Kozo
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): TRICE, RONALD
• Application Number:
  US08/123,847
• Time in Patent Office: 677 Days
• Field of Search: 359/59, 345/92, 345/93
• US Class Current: 349/55
• CPC Class Codes: G02F 1/13624 having more than one switching element per pixel
• CPC Class Codes: G02F 1/136263 Line defects

Abstract

An active matrix display device comprising two pixel electrodes in each rectangular area defined by adjacent signal lines and adjacent scanning lines. The pixel electrodes disposed across each signal line are connected with respective switching elements, which are connected to the common scanning line and the common signal line. In this way, each pixel electrode has only one signal line formed on one side thereof. As a result, a line defect conventionally produced by a leakage between adjacent signal lines through a pixel electrode is prevented. Further, a defective pixel can be easily corrected by short-circuiting the pixel electrode with the adjacent signal line.

Claims

1. An active matrix display device comprising a pair of insulating substrates at least one of which is transparent, a display medium sealed between the insulating substrates, the optical properties of the display medium being modulated corresponding to an applied voltage, a plurality of scanning lines formed on one of the insulating substrates, a plurality of signal lines formed so as to cross the scanning lines on the insulating substrate, two pixel electrodes disposed in each rectangular area defined by the adjacent scanning lines and the adjacent signal lines, and switching elements connecting the pixel electrodes to the scanning lines and the signal lines;

wherein the pixel electrodes are disposed in pairs across each signal line, and the switching elements respectively connected to the paired pixel electrodes are connected to the common scanning line and the common signal line, and

wherein each switching element is formed above a scanning line branch extending from the scanning line including a portion of the scanning line branch, a signal electrode of the switching element is disposed so as to overlap the scanning line branch with the insulating film therebetween, and an electrode portion constituting the switching element and electrically connected to each pixel electrode is disposed so as to overlap the scanning line branch with the insulating film therebetween,

and further wherein said scanning line branch and said switching element constitute a repair structure for a defective connection between said switching element and said pixel electrode, by cutting said scanning line branch, and by short-circuiting said two overlapping electrode portions of said switching element, thereby electrically connecting said pixel electrode to said common signal line.

2. An active matrix display device according to claim 1, wherein the scanning line branch has a narrow portion between the branch point from the scanning line and the portion where the switching element is formed, the narrow portion having such a width that the scanning line branch can be easily cut at that portion.

3. An active matrix display device according to claim 1, wherein the width is 5 to 15 μ

m.

4. An active matrix display device comprising a pair of insulating substrates at least one of which is transparent, a display medium sealed between the insulating substrates, the optical properties of the display medium being modulated corresponding to an applied voltage, a plurality of scanning lines formed on one of the insulating substrates, a plurality of signal lines formed so as to cross the scanning lines on the insulating substrate, two pixel electrodes disposed in each rectangular area defined by the adjacent scanning lines and the adjacent signal lines, and switching elements connecting the pixel electrodes to the scanning lines and the signal lines;

wherein the pixel electrodes are disposed in pairs across each signal line, and the switching elements respectively connected to the paired pixel electrodes are connected to the common scanning line and the common signal line,

wherein each switching element is formed above or below a scanning line branch extending from the scanning line including a portion of the scanning line branch, a signal electrode of the switching element is disposed so as to overlap the scanning line branch with the insulating film therebetween, and an electrode portion constituting the switching element and electrically connected to each pixel electrode is disposed so as to overlap the scanning line branch with the insulating film therebetween, and

wherein the active matrix display device further comprises a conductive portion, one end of said conductive portion is overlapping the pixel electrode with an insulating film and conductive piece therebetween, and the other end of said conductive portion is overlapping a projection portion of the signal line with an insulating film therebetween which acts as a repair structure for a defective connection between said switching element and said pixel electrode, by short-circuiting said two overlapping portions of said conductive portion, thereby electrically connecting said pixel electrode to said common signal line, whereby the pixel is lightened to an average brightness of all pixels connected with said signal line.

5. A method of fabricating and repairing a liquid crystal display, the method comprising:

forming at least two source buses on a first of a pair of insulating substrates, the sources buses being formed parallel to one another;

forming at least two scanning lines on the first of the insulating substrates, the scanning lines being parallel to one another and substantially orthogonal to the source buses;

forming a pair of pixel electrodes in a region bordered by a first and a second of the source buses and by a first and a second of the scanning lines;

forming a first switching device for driving a first pixel electrode of the pixel electrode pair and a second switching device for driving a second pixel electrode of the pixel electrode pair, the first switching device serving to drive the first pixel electrode of the pair when a source signal is carried on the first of the source buses and a scanning signal is carried on the first of the scanning lines, the second switching device serving to drive the second pixel electrode of the pair when a source signal is carried on the second of the source buses and a scanning signal is carried on the first of the scanning lines;

determining whether a defect exists in the first pixel electrode of the pair and, if the defect exists;

shortcircuiting the first pixel electrode of the pair to the first source bus.