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Expired Canadian patentCanada

Focusing control circuitry for an optical memory system

CA 1210151 A · Owner: Burroughs Corporation (Delaware) · Inventors: Hsieh, Der-Chang; Labudde, Edward V.

CIPO record

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Its claims, description and drawings are in the Canadian Patents Database.

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Abstract From the Canadian patent

An optical storage system employing a lasesr beam which is directed and focused onto an optical disk for reading and/or writing data in a track of the disk. Proper focusing is maintained using focusing control circuitry which produces a focus error signal that is applied to a focus motor. This focusing control circuitry is able to return the objective lens assembly to its in-focus position so long as the objective lens assembly remains within a predetermined capture range. In the event that the objective lens assembly is outside of this capture range, a waveform generator is enabled which produces a correction signal that causes the focus motor to move the objective lens assembly back …

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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

  • Granted August 19, 1986. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended August 19, 2003.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledMay 18, 1983
GrantedAugust 19, 1986
Term endedAugust 19, 2003
Patent numberCA 1210151 A
Classification (IPC)G11B7/09 +2 more

Timeline

Timeline From CIPO dates

1984198619881990199219941996199820002002Application filedMay 18, 1983Patent grantedAug 19, 1986Term endedAug 19, 2003

Sources & verification

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