Apparatus for optically reading a record carrier and correcting focus error
US4074314A · kind A · utility
24Cited by
7References
1Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Aug 27, 1976 |
| Grant date | Feb 14, 1978 |
| Priority date | — |
| Expiry date | Aug 27, 1996 |
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. An optical wedge-field lens combination extends the range of operation of the focus correction device.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.