Precision speed control for optical scanners
US4140903A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 3, 1977 |
| Grant date | Feb 20, 1979 |
| Priority date | — |
| Expiry date | Jan 3, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2201/04794
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
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 drive voltage applied to the motor windings. 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 of each scan line. The start of scan signal is amplified and compared in a phase detector with a reference frequency corresponding to the desired optical scanner speed. The phase detector generates a voltage signal representing the phase difference between the start of scan signal and the reference frequency due to variations in the motor speed. This signal is then modulated. The resultant signal modulates the amplitude of both of the signals utilized to drive the motor field windings, the motor torque being adjusted in response to this drive signal charge whereby the hunting in the motor is effectively damped out.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.