Tracking servo apparatus for carrying out tracking by eliminating an offset component from an output signal and method therefor
US5982722A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 16, 1996 |
| Grant date | Nov 9, 1999 |
| Priority date | — |
| Expiry date | Jan 16, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0901
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An offset component extracting circuit is supplied with a tracking error signal TE' obtained by using the push-pull method and including an offset component resulting from optical axis deviation, etc. of the object lens followed by tracking. The offset component extracting circuit extracts, from the tracking error signal TE', an offset component included in the tracking error signal itself. A hold circuit outputs offset component S1 delivered from the offset component extracting circuit as offset component S2 as it is for a time period during which servo is in OFF state on the basis of a servo command signal delivered from a system controller to hold the offset component S1 when servo operation changes from OFF state to ON state to output the offset component S1 thus held as offset component S2. A differential amplifier subtracts the offset component S2 from the tracking error signal TE' to deliver a tracking error signal TE from which the offset component S2 has been eliminated to a tracking control circuit through a switch 15. The tracking control circuit includes, e.g., a phase compensation circuit, etc. in the servo control, and drives, e.g., biaxial device of the optical pick-…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.