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Expired Canadian patentCanada

Magneto-optical recording method using a magneto-optical recording medium having two or more magnetic layers to allow recording and reproduction to be effected simultaneously and magneto-optical recording medium used in the method

CA 2073924 C · Owner: Hongu, Kazuoki · Inventors: Kobayashi, Tadashi; Yamamoto, Masakuni; Hasegawa, Koyo

CIPO record

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Abstract From the Canadian patent

A magneto-optical recording method employs a magneto-optical recording medium having a first magnetic layer which exhibits low coercive force at room temperature and high Curie temperature and a second magnetic layer which is exchange-coupled to the first magnetic layer and which exhibits a higher coercive force and a lower Curie temperature as compared with those of the first magnetic layer. A magnetic field modulated in accordance with information to be recorded is applied to the magneto-optical recording medium while irradiating it with a light beam of a constant intensity so as to record the information. The recorded information is simultaneously confirmed by using a reflected light of …

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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.

Why it's free to use

  • Filed July 15, 1992 and granted March 4, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended July 15, 2012.
  • A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by July 15, 2014.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledJuly 15, 1992
GrantedMarch 4, 1997
Term endedJuly 15, 2012
Patent numberCA 2073924 C
Classification (IPC)G11B13/04 +1 more

Timeline

Timeline From CIPO dates

1993199519971999200120032005200720092011Application filedJuly 15, 1992Patent grantedMarch 4, 1997Term endedJuly 15, 2012

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Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.