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:
Mar. 21, 2000
Filed:
Jan. 30, 1998
Jay Friedman, Felton, CA (US);
Candescent Technologies Corporation, San Jose, CA (US);
Abstract
A device for and method of eliminating objectionable bands of uneven brightness in flat panel field emission displays (FEDs). Within the FED screen, a matrix of rows and columns is provided and emitters are situated within each row-column intersection. Rows are activated sequentially by row drivers and discrepancies in row driver settling times among the row drivers cause bands of uneven brightness on the display screen. The present invention normalizes row settling time of row driver integrated circuits that can be variant due to differences in semiconductor processing and manufacturing. The present invention includes specialized circuitry coupled to the row drivers for sensing an output of the row driver and determining a difference between the output and a threshold at a particular time before the output has completely settled to a target voltage. In response to the difference, gate voltages of output transistors within the row driver are altered in order to adjust the settling time of the row driver to match a target settling time. As a result, the settling times of all the row drivers in the FED screen are matched. Consequently, the brightness variation problem is eliminated.