Patent ID: 6598797
Filing Date: 2003-07-29
Classification: G06K

Abstract:
A method of focusing an optical symbology utilizing a set of illumination parameters including intensity, exposure time and gain comprising the steps of:capturing an image of said optical symbology in an active area of a two dimensional photodetector; providing at least two focusing zones of said optical symbology, controlling said two dimensional photodetector to receive said image of said optical symbology for each of said ay least two focusing zones in said active area with a first level of one of the parameters; said active area of said two dimensional photo-detector shifting out said image data substantially serially, first evaluating transitions between light and dark data in a central set of scan lines, producing a representative value for each of said at least two focusing zones, and determining a first relative focus value based upon a largest of said representative values; controlling said two dimensional photodetector to receive said image of said optical symbology for each of said at least two focusing zones in said active area with a second level unequal to said first level of said one of the parameters; said active area of said two dimensional photodetector shifting out said image data substantially serially; evaluating transitions between light and dark data in a central set of scan lines producing a representative value for each of said at least two focusing zones and determining a second relative focus value based upon a largest of said representative values; comparing said first and second relative focus values to determine an optimum focus; and wherein at least two levels of one of the parameters is used to focus the optical symbology.