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:
Jun. 02, 1987
Filed:
Sep. 27, 1984
Fred F Hubble, III, Rochester, NY (US);
Randolph H Bullock, Rochester, NY (US);
Li-Fung Cheung, Los Angeles, CA (US);
Robert E Crumrine, East Rochester, NY (US);
James P Martin, Dansville, NY (US);
Peter P White, Schaumburg, IL (US);
Mehrdad Zomorrodi, Culver City, CA (US);
Xerox Corporation, Stamford, CT (US);
Abstract
The present invention is concerned with a self-adjusting document sensor compensating for degradation of the sensor system. A suitable light source and a detector are provided, the output of the detector being fed into an amplifier whose gain depends upon a feedback signal. Periodically, the output of the amplifier is compared to a reference. If the output of the amplifier falls below the reference, a pulse is sent to a ripple counter whose digital output is fed back to the amplifier to change the gain of the amplifier. If the detector is an unbiased photodiode operating in the transconductance mode, the leakage currents and their subsequent effect on output with amplifier gain changes will be minimized.