05949054 is referenced by 183 patents and cites 21 patents.

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.

Title
Bar code reader for reading high to low contrast bar code symbols
Application Number
8/546588
Publication Number
5949054
Application Date
October 23, 1995
Publication Date
September 7, 1999
Inventor
Brian L Jovanovski
Syracuse
NY, US
Dennis W McEnery
Marcellus
NY, US
William H Havens
Skaneateles
NY, US
Thomas W Karpen
Skaneateles
NY, US
Agent
Wall Marjama Bilinski & Burr
Assignee
Welch Allyn
NY, US
IPC
G06K 7/10
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