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:
Nov. 14, 2000
Filed:
Sep. 30, 1998
Ronald L Hansen, San Jose, CA (US);
Candescent Technologies Corporation, San Jose, CA (US);
Abstract
A circuit and method for controlling the brightness of a display screen implemented using a flat panel field emission display (FED) screen. 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 and separate gray scale information is presented to the columns. When the proper voltage is applied across the cathode and anode of the emitters, they release electrons toward a phosphor spot, e.g., red, green, blue, causing an illumination point. The present invention includes brightness control circuitry positioned across the row drivers for altering row on-time of the applied voltage to the rows causing a uniform change in brightness cross the FED screen. The applied voltage is pulse width modulated to alter the brightness of the FED screen. Because the relative column voltages remain constant within the present invention, gray scale resolution or the gamma or the white point balance of the screen is not compromised as brightness is altered. Brightness is increased for an increase in the on-time window and decreased for a decrease in the on-time window.