Optical unit for use in image-forming apparatus
US5136160A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 22, 1991 |
| Grant date | Aug 4, 1992 |
| Priority date | — |
| Expiry date | Feb 22, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2201/04744
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In an optical unit, a light beam is emitted from a light source toward a given object. Part of the light beam is reflected by a reflecting mirror and is returned to a monitor diode which is incorporated in the light source. The reflecting mirror is arranged in an optical path along which the light beam is directed from the light source to the object, but is located outside of an image region containing an optical axis and expanding in the main scanning direction. By use of the light beam returned to the monitor diode, the deflection start position from which the light beam emitted from the light source is deflected is detected. In other words, the deflection start timing is detected. A variation in the monitor current produced by the monitor diode is utilized for controlling the light source, to thereby match the horizontal synchronization.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.