Gtech Corporation

Henry J Constant, Jr

Steven A Bozzi

Bruce I Parkes

A method and apparatus for generating and applying quality factors (QFs) to an optical reader. After an optical reader is calibrated, a mid-range gray scale level is selected and scanned. The reader outputs digital numbers (DNs) that are generated for all the pixels that will be responding to the reading of a document. A histogram of the DNs is generated and characteristics of the histogram distribution are calculated and used as QFs. For example, the standard deviation of the histogram may serve as a QF, where a lower standard deviation is preferred. Thresholds and standards may be developed from experience that indicate the operating condition of the reader. The QFs, thus, may be used during manufacturing and for field servicing of the reader.

Optical reader quality factor

A method and system for calibrating optical reader systems employs a target with areas comprising linear gray scale levels. The gray scale levels include the darkest and the lightest scenes. The gray scale levels are illuminated by an array of LEDs and the light reflected from target impacts photo-transistors. The photo-transistors are biased in their linear ranges and the target is scanned while the LED drive current is changed. The photo-transistor responses to the different gray scale levels at the different LED drive currents are analyzed, and the LED rive current that produces a linear output from the photo-transistors over the gray scale dynamic range is selected. Several video channels may be used and their offsets and gains are normalized. Black offsets and black to white gain correction functions are generated for balancing or correcting each pixel. The correction functions may be applied by a processor for later raw image data of scenes scanned by the optical reader.

System and method for calibrating an optical reader system

An optical reader with a single optical assembly that receives images from at least two different environments. For example, one environment may be constructed in a first chamber into which a document or bulk item with a bar code may be placed. The other environment may be constructed in a second chamber with an active drive mechanism that transports a document with optical readable markings to a reading location. The environments may be separated by a baffle that prevents light from leaking between the environments, and the electronics and software are constructed to read and decode information that is found in the images from both environments either sequentially or simultaneously.

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West Warwick, RI, United States of America

Henry J Constant, Jr