Apparatus for optically reading a record carrier by means of an autofocus device
US3992575A · kind A · utility
14Cited by
5References
5Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Nov 26, 1974 |
| Grant date | Nov 16, 1976 |
| Priority date | — |
| Expiry date | Nov 26, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0924
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An apparatus is described for reading a record carrier on which information is stored in an optically readable reflecting structure. By projecting two radiation spots one before and one behind the plane of the information structure, it is possible to ascertain whether a read beam is properly focussed on the information structure.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.