The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 14, 1993
Filed:
Jul. 10, 1992
Walter N Zalph, Boca Raton, FL (US);
International Business Machines Corp., Armonk, NY (US);
Abstract
A TFT LCD display has a PEL matrix in which the drain lines of the different TFTs are supplied with different drain voltages to achieve a preset number of gray scales. The different drain voltages are set during factory calibration through use of a test PEL having substantially the same characteristics as the PELs viewable by a user. The characteristics of the test PEL are first measured, the values of drain voltages for achieving the different gray scales are mathematically derived from the measurements, and such values are stored in the display system. The specific manner in which calibration is done is by measuring output voltages of a photodiode located next to the test PEL as a function of different drain voltage inputs and constructing a unique transmissivity versus drain voltage for the subject display. Calibration is accomplished by a factory tester or by a built-in calibration system.