The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 10, 1979
Filed:
Sep. 13, 1977
David E Damouth, Rochester, NY (US);
William F Gunning, Los Altos Hills, CA (US);
Xerox Corporation, Stamford, CT (US);
Abstract
A motor speed control system for reducing instantaneous speed variations as a result of hunting in hysteresis synchronous motors utilized to drive optical scanners by controlling the frequency of the drive signal applied to the motor. A laser beam is reflected from the facets of the optical scanner and scans a surface along a scan line, a signal being generated at the start and end of each scan line. A counter is driven by an accurate clock which is started and stopped in accordance with the start and end of scan signals. The resulting count of the counter is thus inversely proportional to the speed of the motor and is converted to an analog input signal and coupled to a voltage controlled oscillator whose frequency is controlled for driving the motor such that undesirable oscillations of the motor are damped out. Additional embodiments for controlling the motor speed are disclosed which utilize only the start of scan signal to both start and stop the counter.