An automatic projection laser scanning system for reading bar code symbols. The system is supportable on or above a countertop surface, and includes a laser scanning device having a compact housing from which it automatically produces an object detection field of volumetric expanse for automatic detection...http://www.google.com.tw/patents/US5661292?utm_source=gb-gplus-share專利 US5661292 - Automatic laser projection scanner with improved laser beam scanning efficiency
