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. 11, 1994
Filed:
Dec. 14, 1992
Steven L Webb, Loveland, CO (US);
Edward S Beeman, Loveland, CO (US);
Kenneth D Gennetten, Fort Collins, CO (US);
Craig L Miller, Boise, ID (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A document scanner is disclosed wherein means are provided to dynamically compensate for any changes in document illumination intensity that may occur as a document is scanned. The compensation method and apparatus operates to measure the intensity of light that is reflected from a target area that borders an edge of the document being scanned. The target area is a narrow, elongated, area that extends in the scan direction. The target area is of a color to approximate the document's background area, i.e. the document's nonimage area. Since the target area is of a continuous and uniform color tone, any variation in the quantity of light that is reflected from the target area is caused by a variation in the intensity of illumination thereof by the scanning light source. The method and apparatus of the invention controls the scanning light source so as to maintain the light reflected from the target area at a substantially constant magnitude.