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. 02, 1979
Filed:
Mar. 14, 1977
James G Tisue, Mountain View, CA (US);
Rapicom Inc., Santa Clara, CA (US);
Abstract
A compensation circuit for use in a document reproduction system for correcting variations in white level occurring between different documents and due to nonuniformity of the scanning process including a variable voltage gain amplifier for compensatingly modifying the output of an image scanner and having a gain control system which drives the white level amplifier gain to a predetermined level so that the scanner output is made independent of certain well known causes of nonuniformity. The gain control system includes a comparator which compares the amplifier output to a white reference signal, a counter having a start count which may be present and which is incremented when the comparator output indicates that the amplifier output exceeds the reference signal, a memory which is addressed by signals developed by the scanner and which stores the output of the counter at intervals which in effect subdivide each scan line, the stored signals being used to preset the counter at the beginning of each particular scan interval, and a digital-to-analog converter for converting the counter output to a form which can be used to drive the amplifier.