Optical scanning for record carriers adapted for reading with differing wavelengths
US5235583A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 25, 1992 |
| Grant date | Aug 10, 1993 |
| Priority date | — |
| Expiry date | Feb 25, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0938
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A device in which a radiation source generates a radiation beam of a first wavelength. The scanning spot 7 generated by this radiation beam follows the centerline 13 of a track 8 to be scanned on a first type of record carrier designed for this wavelength. When a second type of record carrier is being read, in which the information is stored in a phase structure designed for a wavelength which is longer than the first wavelength, the read spot 7 follows the edge of a track 38 to be read instead of the centerline 18. In this way it is possible to generate a satisfactory information signal not only from the first type of record carrier but also from the second type of record carrier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.