Opto-magnetic disk unit with improved dynamic range characteristics and opto-magnetic disk therefor
US5034934A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 17, 1989 |
| Grant date | Jul 23, 1991 |
| Priority date | — |
| Expiry date | Jan 17, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2220/2525
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An opto-magnetic disk unit is constructed so that predetermined areas existing in the front of the unit recording areas can be detected. In addition, at least one of first and second saturation magnetizations are recorded on each of the detected predetermined areas. At the time of reproduction, signal processing on the output of the pickup is performed after a part of the output of the pickup corresponding to the one section of the predetermined area is clamped to a predetermined level. Also at the time of reproduction, gain controlling of a circuit for signal processing the output of the pickup may be performed based on the level difference between the signal read from a first saturation magnetization section and the signal read from a second saturation magnetization section. An opto-magnetic disk is also provided having recording areas including at least one of first and second magnetization saturation levels arranged in the front of the unit recording areas.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.