Optical head with a tilt correction servo mechanism
US5216649A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 19, 1989 |
| Grant date | Jun 1, 1993 |
| Priority date | — |
| Expiry date | Jun 19, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1395
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical head device includes a tilt servo mechanism using photodetectors for detecting rays of light reflected from the recording surface of an optical disk. The rays of light are obtained from a laser diode used as a light source for information reproduction. According to one aspect; prisms are formed on the flange of a converging lens to refract peripheral portions of the light emitted from the laser diode for tilt detection. According to another aspect, secondary diffraction grating domains at the sides of the primary diffraction domain of a diffraction grating diffract peripheral portions of the emitted rays of light for tilt detection. According to another aspect, a mirror reflects peripheral portions of the emitted rays from the laser diode. According to a further aspect a mirror reflects the light from the laser diode passing through a beam splitter. Each photodetector receiving the light reflected from the recording surface of the disk may be partitioned into two detector cells, and a tilt signal is obtained as the differential output of the two cells.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.