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US4417290A Expired / Lapsed US ⏱️ 0.0 years remaining

Multi-layer magneto-optical recording medium

Assignee: KDDI Corp
•
Filing: 1981-08-19
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Granted: 1983-11-22
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Expires: 2001-08-19
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Abstract

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.

Inventors

  • 👤 Shinsuke Tanaka
  • 👤 Nobutake Imamura
  • 👤 Chuichi Ota

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-24 04:27
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B7/00; G11B7/24

Claims Analysis

Total Claims: 2
Claim 1
Independent Claim 89 words
A multi-layer magneto-optical recording medium comprising a magneto-optical recording substrate wherein an easy axis of magnetization is provided perpendicular to a film surface and the direction of magnetization is perpendicular to the film surface to take a binary code depending on whether the direction of magnetization is upward or downward, a transparent protective film placed upon said magneto-optical recording substrate and a metal film having a melting point lower than that of both said transparent protective film and said magneto-optical recording substrate is disposed upon said transparent protective film.
Claim 2
Dependent Claim 89 words
A multi-layer magneto-optical recording medium comprising a magneto-optical recording substrate wherein an easy axis of magnetization is provided perpendicular to a film surface and the direction of magnetization is perpendicular to the film surface to take a binary code depending on whether the direction of magnetization is upward or downward, a transparent protective film placed upon said magneto-optical recording substrate and a metal film having a melting point lower than that of both said transparent protective film and said magneto-optical recording substrate is disposed upon said transparent protective film.

References Cited (Backward Citations)

US3928870A Cited
US4202932A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1986-11-21 1987-05-23 1987-11-22 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1990-11-21 1991-05-23 1991-11-22 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1994-11-21 1995-05-23 1995-11-22 $7700.00 Window Closed / Lapsed

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