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. 18, 2003
Filed:
Sep. 05, 2000
Terence John Nelson, New Providence, NJ (US);
Other;
Abstract
A low-cost, large-area display system having a backlight in segments each positioned to illuminate a subfield of M rows of a fast supertwisted-nematic (STN) display of N rows. Fields of Q+1 subfields are addressed by the method known as Active Addressing using orthogonal waveforms of period MT/N where T is the frame time. A subfield is addressed for Q+1 periods MT/N of the row waveforms and illuminated during the last one. Fast STNs allow Q to be small leading to a small effective multiplex ratio with improved contrast and horizontal viewing-angle range. A few additional leading and trailing rows may be addressed to overcome vertical parallax. The row drivers are periodically connected by switches that simply ground un-addressed rows. With Q+1 also a divisor of N, subfield contributions to the column waveforms can be calculated once and used Q+1 times in each frame. For example, N=240, M=16, L=4 and Q=2 provide an effective multiplex ratio of 57 and allow at least 2.2 msec for pixels to turn on when the frame rate 1/T is 60 Hz. The viewing-angle range can also be expanded by moving subfields a few rows in the scan direction and advancing the integration time to equalize the brightness of pixels illuminated by the next segment. For example, if the turn-off time is 0.76 T and the integration time is shortened to 0.33 MT/N, equalization is possible with turn-on times as large as ¾ of the turn-off time without decreasing pixel transmittance by more than 50%. Dual-scan configurations using N=240, for example, can display VGA or 480 p formats.