Multi-layer magneto-optical recording medium
US4417290A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 19, 1981 |
| Grant date | Nov 22, 1983 |
| Priority date | — |
| Expiry date | Aug 19, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/24
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A multi-layer magneto-optical recording medium is constructed by placing a transparent protective film upon a magneto-optical recording medium wherein the easy axis of magnetization is provided perpendicular to the film surface so as to make the direction of magnetization perpendicular thereto to take a binary code depending on whether the vertical direction thereof is upward or downward, and further by placing a metal film, of which melting point is lower than either said magneto-optical recording medium and said transparent protective film, upon said transparent protective film. The metal film is evaporated by a laser beam irradiated thereon in a manner to leave a portion thereof not evaporated to become a tracking guide, whereby reproducing a magneto-optical record free of disturbance on linear polarization. The metal film can be perforated to form pits by irradiation of a laser beam. Presence or absence of such pits can be used for storing data and, therefore, is applicable for a read-only memory of optical method or an optical video disc.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.