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. 28, 1995
Filed:
Nov. 24, 1992
James G Hagerman, San Diego, CA (US);
Other;
Abstract
Improved bias drive and noise reduction techniques for use with and image projector, such as a liquid crystal light valve image projector. A bias drive circuit produces a square wave-like signal to drive the liquid crystal light valve, for example, with a square wave signal. The square wave-like signal is phase-locked to the vertical refresh (vertical sync) signal of the projector. A frequency synthesizer is used to drive the bias drive circuit wherein the noise is interlaced by using every other field as the sync reference input to the bias drive circuit. The bias drive circuit is unique in how it reduces unwanted visual noise effects in a displayed image by waveshaping the drive signal and interlacing and phase-locking it to the vertical refresh signal of the projector. These aspects of the present invention combine to virtually eliminate visual noise in the projected image. An optional variable gain circuit may be provided that provides the ability to set the amplitude of the bias provided by the bias drive circuit to the cut-in operating point of the liquid crystal light valve.