Tracking circuit for guiding a beam of light along data tracks of a recorded medium
US5136568A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 22, 1991 |
| Grant date | Aug 4, 1992 |
| Priority date | — |
| Expiry date | May 22, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/094
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A tracking circuit for guiding a beam of light along data tracks of a recorded medium as compact disks and video disks, in which the recorded medium reflects a light beam onto a photodetector. The photodetector has an output voltage that is applied to a servo through a variable-gain amplifier. A compensation voltage is superimposed over the output voltage from the photodetector during the open state of the circuit to compensate off said voltages. This compensation voltage is varied until the sum of the output voltage from the photodetector and the compensation voltage attains a predetermined value. Thereafter the circuit is closed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.