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Repair method for point defect of LCD

IP.com Disclosure Number: IPCOM000015584D
Original Publication Date: 2002-Feb-15
Included in the Prior Art Database: 2003-Jun-20
Document File: 5 page(s) / 74K

Publishing Venue

IBM

Abstract

Disclosed is the repair method for point defect (defective pixel) in the thin film transistors (TFT) array substrate ,which has IPS (In Plane Switching mode)-HRP(High Resolution Process) structure, for use in a liquid crystal display (LCD) device. This structure has the character that common electrodes made of ITO (Indium-Tin Oxide) are located immediately above signal and gate lines. Therefore, the pixel electrode in defective pixel is connected with the pixel electrode in adjacent normal pixel via the common electrodes between the two pixels by means of the laser CVD method. Moreover, in order to separate electrically the common electrodes and the repaired portions, the common electrodes are cut off completely by the laser beam. The cut sections have the depth not to cut off the gate and signal lines located immediately below the common electrode. FIG.1 is a plan view showing the thin film transistors (TFT) array substrate of IPS- HRP type liquid crystal display (LCD) device in the display area. FIG. 2 shows a sectional shape at the position corresponding to a X-X’ line in FIG. 1. The glass substrate 1 is provided with TFT 2 having signal lines 3, gate lines 4, storage capacitor lines 5, common electrodes 6, pixel electrodes 7, an amorphous silicon layer and the like deposited thereon. The TFT 2 is a switching element for controlling a drive voltage to the pixel electrode 7, and is provided on an intersection portion of the signal line 3 and the gate line 4. Each signal line 3 is the one for transmitting a display signal to the TFT 2, arranged on the insulating layer 8A, and provided to be extended in a predetermined direction at each predetermined interval. Each gate line 4 is the one for transmitting a scanning signal to the TFT 2, arranged on the glass substrate 1, and provided so as to be extended in a direction approximately perpendicular to that where each signal line 3 continues at each predetermined interval. Each storage capacitor line 5 extended in parallel to the gate line 3 is provided and electrically connected to each common electrode 6 in the outer peripheral portion. Here, the storage capacitor line 5 is arranged so as to cross the central portion in the vertical direction of each pixel region 9 which is defined by being surrounded by two signal lines 3 adjacent to each other and two gate lines 4 adjacent to each other. The common electrodes 6 made of ITO (Indium-Tin Oxide) are provided on the insulating layer 8B, and are formed in an approximately lattice type so as to be located immediately above the respective signal lines 3 and the gate lines 4. It should be noted that the common electrodes 6 are set to have width wider than those of the signal line 3 and the gate line 4. Here, for the insulating layer 8B, the same material as that of transparent resist capable of securing a large film thickness (several micrometers) that is about ten times larger than a conventionally used nitride film or the like (film thickness: less than 1micrometer), for example, acrylic resin or the like is used. The pixel electrodes 7 made of ITO are electrically connected to the source electrodes 10 of the TFT 2 via the contact holes 11 formed in the insulating layer 8B. The point defect of IPS- HRP type LCD device is repaired as described in the following. First, as shown in FIG. 3, the conductive film 4B (metal film) for connecting electrically the upper pixel electrodes 1A of the defective pixel 2D and the common electrodes 3 is formed by the laser CVD method. In the same manner, the pixel electrodes 1U of the upper adjacent (no defective) pixel 2U and the common electrodes 3, the lower pixel electrodes 1B of the defective pixel 2D and the common electrodes 3, the pixel electrodes 1L of the lower adjacent (no defective) pixel 2L and the common electrodes 3 are connected by the conductive film 4A, 4C and 4D respectively. Here, the only conductive film 4C formed between the lower pixel electrodes 1B of the defective pixel 2D and the common electrodes 3 need to be detour the cut portion 5 by the laser beam. Accordingly, the pixel electrodes 1A and 1B in the defective pixel 2D, the pixel electrodes 1U in the upper adjacent pixel 2U and the pixel electrodes 1L in the lower adjacent pixel 2L are connected electrically by the conductive film 4A, 4B, 4C, 4D. Then, in order to separate electrically the formed conductive film 4A, 4B, 4C, 4D and the common electrodes 3, the common electrodes 3 are cut off completely by the laser beam at four positions 6A, 6B, 6C, 6D which are in the vicinity of the formed conductive film 4A, 4B, 4C, 4D respectively. The cut sections have the depth not to cut off the gate line 7 located immediately below the common electrodes. Moreover, the upper and lower pixel electrodes 1A, 1B in the defective pixel 2D are cut off completely by the laser beam at two positions 7A, 7B respectively which are in the 1

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Repair method for point defect of LCD

   Disclosed is the repair method for point defect (defective pixel) in the thin film transistors (TFT) array substrate ,which has IPS (In Plane Switching mode)-HRP(High Resolution Process) structure, for use in a liquid crystal display (LCD) device. This structure has the character that common electrodes made of ITO (Indium-Tin Oxide) are located immediately above signal and gate lines. Therefore, the pixel electrode in defective pixel is connected with the pixel electrode in adjacent normal pixel via the common electrodes between the two pixels by means of the laser CVD method. Moreover, in order to separate electrically the common electrodes and the repaired portions, the common electrodes are cut off completely by the laser beam. The cut sections have the depth not to cut off the gate and signal lines located immediately below the common electrode.

FIG.1 is a plan view showing the thin film transistors (TFT) array substrate of IPS- HRP type liquid crystal display (LCD) device in the display area. FIG. 2 shows a sectional shape at the position corresponding to a X-X' line in FIG. 1. The glass substrate 1 is provided with TFT 2 having signal lines 3, gate lines 4, storage capacitor lines 5, common electrodes 6, pixel electrodes 7, an amorphous silicon layer and the like deposited thereon. The TFT 2 is a switching element for controlling a drive voltage to the pixel electrode 7, and is provided on an intersection portion of the signal line 3 and the gate line 4. Each signal line 3 is the one for transmitting a display signal to the TFT 2, arranged on the insulating layer 8A, and provided to be extended in a predetermined direction at each predetermined interval. Each gate line 4 is the one for transmitting a scanning signal to the TFT 2, arranged on the glass substrate 1, and provided so as to be extended in a direction approximately perpendicular to that where each signal line 3 continues at each predetermined interval. Each storage capacitor line 5 extended in parallel to the gate line 3 is provided and electrically connected to each common electrode 6 in the outer peripheral portion. Here, the storage capacitor line 5 is arranged so as to cross the central portion in the vertical direction of each pixel region 9 which is defined by being surrounded by two signal lines 3 adjacent to each other and two gate lines 4 adjacent to each other. The common electrodes 6 made of ITO (Indium-Tin Oxide) are provided on the insulating layer 8B, and are formed in an approximately lattice type so as to be located immediately above the respective signal lines 3 and the gate lines 4. It should be noted that the common electrodes 6 are set to have width wider than those of the signal line 3 and the gate line 4. Here, for the insulating layer 8B, the same material as that of transparent resist capable of securing a large film thickness (several micrometers) that is about ten times larger than a conventionally us...