Magnetic recording using recording media having temperature dependent coercivity
US4277806A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 14, 1979 |
| Grant date | Jul 7, 1981 |
| Priority date | — |
| Expiry date | May 14, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2005/0021
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A magnetic recording which is useful as a mirror image duplication video tape master is made from another magnetic recording by anhysteretic transfer at a temperature at which the coercive force of the master is much less than the coercive force of the other recording. Preferably, the magnetic recording layer of the master comprises fine particles of a manganese bismuth alloy, the coercivity of which decreases with decreasing temperature, and the other record comprises a magnetic recording layer having a coercivity which increases with decreasing temperature. The master record may subsequently be used to duplicate copies of the recording by anhysteretic transfer to a copy record having a coercive force which, at the temperature at which the transfer is made (typically room temperature), is substantially lower than the coercive force of the master.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.