Videodisc focusing and tracking servo
US4773055A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 6, 1987 |
| Grant date | Sep 20, 1988 |
| Priority date | — |
| Expiry date | Nov 6, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0925
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An electro-optical apparatus comprising an objective (7) scans an optical disc (3) having a transparent protective layer (5) by means of a radiation beam (10) which, through the transparent layer, is focussed on a reflecting recording surface (4). The objective moves along the optical axis (19) for focussing the radiation beam on the recording layer and moreover performs limited pivotal movements. The position of the optical axis of the objective is corrected for obliquity of the surface of the optical disc, correction means (22A, B) being provided to tilt the objective through a correction angle, so that the angle between the optical axis and the normal to the disc surface is reduced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.