A scanner has a window in its housing through which the scanning beam emerges to impinge upon an indicia to be read. The window is elongate, and adjacent each end, on the inside of the housing, there is a bar code symbol structure. In use, the scanning beam first scans across the symbol structure at...http://www.google.com.au/patents/US6005255?utm_source=gb-gplus-sharePatent US6005255 - Timing synchronization for image scanning
