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专利名称：Signal processing for print scanners发明人：Giancarlo Punis申请号：US05/653450申请日：19760129公开号：US04020357A公开日：19770426
摘要：Laser light scattered from a UPC symbol on a moving web is detected by aphotomultiplier, and detection threshold levels and print contrast signals are developedon a time varying analog basis. Since the reflected light includes an ambient component,the \"white\" and \"dark\" logical thresholds are developed based on the voltage levels ofpeak above zero, white to dark as a time variant function, and respective maximum valuesthereof. When a valid UPC signal is detected, present signal parameters develop printcontrast (i.e., white minus dark/white) and produce a gate pulse having a durationproportional to that ratio.
申请人：METROLOGIC INSTRUMENTS, INC.
代理机构：Paul & Paul
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