Focus error detecting circuit for disk player
US4992652A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 5, 1989 |
| Grant date | Feb 12, 1991 |
| Priority date | — |
| Expiry date | Dec 5, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0909
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
This invention relates to a focusing error detection circuit employed in an optical pickup of an optical disk apparatus or the like. The laser light received from the recording medium is detected by a photodetector and processed in a focusing error computing device to form a first focusing error signal. The first focusing error signal is sampled and held at the timing of periodic turn-off of the laser beam and the sampled-and-held signal is subtracted from the first focusing error signals to produce a second focusing error signal. The second focusing error signal is freed of adverse effects caused by factors, such as temperature changes of the focusing error computing device thereby enabling the accurate focusing servo control of the optical pickup device.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.