TACHOMETER START OF SCAN DETECTOR
Original Publication Date: 1984-Jun-30
Included in the Prior Art Database: 2004-Apr-04
Xerox Disclosure Journal
The majority of laser scanning systems which exist today use one or more external photodetector circuits to determine the position of the laser spot for start of scan applications. There are several versions of these in use but all of them require the detector to be positioned somewhere in the path of the scanning beam at a reasonable throw from the scanning motor. There is proposed a method in which tachometers are incorporated into the motor housing and used to detect the position of the shaft (and thus the laser spot position) for a simple two facet scanning system. The cost savings in a production environment could be substantial by eliminating the handling and alignment of an external device during manu-facture and service of a printer.