Magnetic field modulation magnet-optical recording apparatus in which an fm modulator and a magnetic head driving circuit are used in common
CA 2073539 C · Owner: Fuji, Hiroshi · Inventors: Fuji, Hiroshi
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A positive-direction current source is connected to a magnetic head coil via a multiplier and a switching device and a negative-direction current source is connected to the magnetic head coil via the switching device. The output current of the positive-direction current source is controlled to a level appropriate for generating a magnetic field forming a magneto-optical recording mark based on the amplitude of an information signal by the multiplier. The switching device is turned on/off by a carrier signal. As a result a magnetic head driving signal can be, obtained having the positive-direction current value modulated based on the amplitude of the information signal.
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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 9, 1992 and granted March 18, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended July 9, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by July 9, 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.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.