Optical disk discriminating device
US5003521A · kind A · utility
53Cited by
5References
8Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Aug 18, 1988 |
| Grant date | Mar 26, 1991 |
| Priority date | — |
| Expiry date | Aug 18, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2220/2537
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An objective lens (3) of an optical pick up head (10) is moved in a direction of the optical axis, and a signal level of the output detected by the optical pick up head (10) before and after a focussed state is compared with predetermined reference levels (Vref.sub.1) and (Vref.sub.2) level comparators (32) and (33), In order to discriminate the reproduction-only disk from the recording disk by utilizing a difference in the reflection factor on the recording surface on the optical disk (20). Operation of the optical disk recording/reproducing apparatus is automatically switched over depending upon the kind of the optical disk.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.