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:
Jul. 09, 2002
Filed:
Nov. 25, 1998
Roger G. Stewart, Neshanic Station, NJ (US);
Alfred C. Ipri, Princeton, NJ (US);
Sarnoff Corporation, Princeton, NJ (US);
Abstract
An emissive display device such as an active matrix electroluminescent display (AMEL display) has an improved method of operation. The AMEL display produces gray scale operation comprising an array of pixels, each pixel including a first transistor having its gate connected to a select line, its source connected to a data line, and its drain connected to the gate of a second transistor. The second transistor has its source adapted to receive a ramped voltage level, and its drain connected to a first electrode of an electroluminescent cell. The electroluminescent cell has a second electrode connected to an alternating current high voltage power source, wherein the electroluminescent cell is illuminated, when the ramp voltage level is less than a voltage level on the gate of the second transistor. The ramp voltage level is increased linearly during a frame duration, and the alternating current high voltage power source is on continuously during the same frame duration. The alternating current high voltage power source may also be varied in amplitude from a minimum peak-to-peak value to a maximum peak-to-peak value during the frame duration.