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:
Sep. 07, 1999
Filed:
Oct. 23, 1995
Thomas W Karpen, Skaneateles, NY (US);
William H Havens, Skaneateles, NY (US);
Dennis W McEnery, Marcellus, NY (US);
Brian L Jovanovski, Syracuse, NY (US);
Welch Allyn, Inc., Skaneateles Falls, NY (US);
Abstract
A bar code reader is provided which can read bar code symbols of varying contrast, from high to medium to low contrast. The bar code reader includes a digitizing circuit which digitizes an analog signal representing the reflectance function of a scanned bar code by comparing the analog signal to a threshold signal. In the present invention, the threshold signal is switchable between a first state wherein the threshold signal is a standard threshold signal suitable for digitizing analog signals representing medium to high contrast bar code symbols and a second state wherein the threshold signal is a non-standard threshold signal suitable for digitizing analog signals representing low contrast bar code symbols. In one embodiment of the invention, the threshold signal is manually adjustable. In another embodiment, a bar code reader is provided which automatically digitizes and decodes bar code symbols of varying contrast by repetitively scanning bar code symbols, using first and second alternating threshold signal states to digitize the analog signal resulting from each scan.