Optical record and reproduction apparatus with liquid crystal panel that rotates light followed by a polarizer or birefringent plate
US5210627A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 30, 1991 |
| Grant date | May 11, 1993 |
| Priority date | — |
| Expiry date | May 30, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1353
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical record and reproduction apparatus, in which a light beam generated by a light source is concentrated onto an information recording medium by a focusing device, and the light beam reflected by the information recording medium is detected by a light detector to obtain a tracking error signal. A liquid crystal panel having a transparent electrode aligned in a striped form and a polarizing plate or birefringent phase difference plate constitute a beam divider for obtaining a main beam and supplementary beams without any accompanying mechanical movement. The beam divider is arranged between the light source and the focusing device. By selectively applying a voltage to the transparent electrode, the liquid crystal panel is made to function in the same manner as a diffraction grating. Another transparent electrode aligned in a striped form at an inclined angle may also be provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.