Method and apparatus for testing LCD panel array prior to shorting bar removal

USRE37847E1 · kind E1 · reissue

Assignee

• PhotoDynamic Inc. · US

Inventors

• Francois J. Henley · Los Gatos, US
• Stephen Barton · Manchester, GB

Key dates

• Filing date: Dec 18, 2000
• Grant date: Sep 17, 2002
• Expiry date: Dec 18, 2020

Classification

• Technology area (CPC —): General

Abstract

Final testing of an LCD panel or the like is performed after preliminary testing for short circuit defects. During final testing, the panel is exposed to signals at the shorting bars and the resulting display pattern is imaged. The resulting image data then is processed at a computer system to determine whether the resulting display pattern differs from an expected display pattern. If differences are present then an open circuit or pixel defect is present. The applied test signals and the pattern or differences determine the type of defect present. For an open circuit defect along a gate line, a partial row (column) of the resulting display pattern does not activate. For an open circuit along a drive line, a partial column (row) of the resulting display does not activate. Pixel shorts are identified by applying test signals to the shorting bars during a first test cycle, then imaging the display during a second test cycle after at least one of the test signals is removed. Pixels which remain active that should be inactive have short circuit defects.