Modulator control for automatically overcoming intensity variations in a laser scanner
US4746987A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 21, 1986 |
| Grant date | May 24, 1988 |
| Priority date | — |
| Expiry date | May 21, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4005
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A scanner with high intensity source beam, a modulator for modulating the source beam to provide a zero order beam and first order writing beam in response to an image signal input, a polygon for scanning the writing beam across a moving recording member to write images thereon, a sensor in the path of the zero order beam providing a first black beam intensity signal while scanning between pages and a second white beam intensity signal while the writing beam scans an image background area, a circuit for differencing the first and second beam intensity signals from one another to provide a composite intensity signal representing the intensity of the source beam, and a second circuit for differencing the composite beam intensity signal from an intensity setpoint signal to provide a correction signal for adjusting the rf power to the modulator to maintain a substantially constant writing beam intensity. In a second embodiment, the correction signal is determined by a successive approximation register.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.