Optical information read apparatus
US4740940A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 6, 1986 |
| Grant date | Apr 26, 1988 |
| Priority date | — |
| Expiry date | Mar 6, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0901
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical information read apparatus for optically reading information recorded on a recording medium includes an optical head for producing two detected signals whose phases vary according to a tracking error of the head, and a tracking error detecting circuit for producing a tracking error signal corresponding to a phase difference between the two detected signals, and a tracking controller for controlling the optical head in response to the tracking error signal. The tracking error detecting circuit has a correlation test circuit for checking a correlation between the states of the two detected signals, and for making the tracking error signal substantially invalid when there is no correlation between the states of the two detected signals. Thus, a stable tracking control can be performed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.