Method and apparatus for automatically inspecting and repairing an active matrix LCD panel

• US 5,235,272 A
• Filed: 06/17/1991
• Issued: 08/10/1993
• Est. Priority Date: 06/17/1991
• Status: Expired due to Term

• Current Assignee: Photon Dynamics Incorporated (KLA Corporation)
• Original Assignee: Photon Dynamics Incorporated (KLA Corporation)
• Inventors: Henley, Francois J.
• Primary Examiner(s): Karlsen, Ernest F.
• Application Number:
  US07/716,592
• Time in Patent Office: 785 Days
• Field of Search: 324/158 R, 324/158 E, 324/158 P, 324/537, 324/527, 324/528, 324/96
• US Class Current: 324/760.01
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/136254 Checking; Testing
• CPC Class Codes: G02F 1/136259 Repairing; Defects
• CPC Class Codes: G09G 2330/10 Dealing with defective pixels
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: Y10S 345/904 Display with fail/safe testing feature

Abstract

LCD panels are inspected in-process to measure pixel decay, turn-on time and parasitic capacitance and/or identify pixel defects and line defects. Prior to final assembly, panels identified as having sufficiently few repairable defects are repaired. Line defects may be repaired. Further pixel defects may be repaired when redundant structures are included by splicing out the defective TFT or storage capacitor and splicing in a redundant, built-in TFT or storage capacitor. The inspection and repair systems are linked through a repair file. The inspection system identifies each defect by type and location and includes such information in the repair file. The repair system accesses such file and follows a prescribed repair method for a given type of defect at the location of such defect. The inspection system includes an automated non-contact voltage imaging system. The repair system includes lasers and means for repairing defects by adding metallization.

Claims

1. A method for identifying pixel defects on an active plate having a pixel array, a plurality of pixel drive elements and a matrix of data lines and gate lines, each one pixel in the array being coupled to one gate line and one data line in the matrix by a pixel drive element, a plurality of data lines of the matrix terminating at a first shorting means, a plurality of gate lines terminating at a second shorting means, the method comprising the steps of:

applying a first timing pattern to the first shorting means and second shorting means;

capturing a voltage image of a first area of the active plate to obtain first pixel voltage data for pixels within said first area;

applying a second timing pattern to the first shorting means and second shorting means;

capturing a second voltage image of a second area of the active plate to obtain second pixel voltage data for pixels within said second area; and

comparing the first pixel voltage data and the second pixel voltage data to identify each pixel common to said first area and to said second area which has a short circuit to a data line.

2. The method of claim 1, further comprising the steps of:

applying a third timing pattern to the first shorting means and second shorting means;

capturing a third voltage image of a third area of the active plate to obtain third pixel voltage data for pixels within said third area; and

identifying a second pixel common to said first area, said second area and said third area as having a short circuit to a gate line by comparing the first, second and third pixel voltage data corresponding to said second pixel.