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:
Jan. 14, 1992
Filed:
Dec. 12, 1990
Thomas J Hammond, Penfield, NY (US);
Xerox Corporation, Stamford, CT (US);
Abstract
An exposure control system for a document copier is enabled by positioning a segmented variable reflectance mirror along the optical imaging path. The mirror segments incorporate a material whose transmission changes in response to applied voltage signals, the preferred material being an electrochromic material. In a first embodiment a white reference strip along the platen surface is exposed and the charge levels along discrete areas of the photoreceptor are measured by an electrometer with a plurality of probe segments. Outputs from each probe segment are processed in a control circuit and a signal sent to an appropriate mirror segment to increase or decrease reflectance to enable a corresponding decrease or increase, respectively, of the charge level, at the corresponding discrete areas of the photoreceptor illuminated by the mirror segments.