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Expired Canadian patentCanada

Servo control system using servo pattern time of flight for read/write head positioning in a magnetic recording system

CA 1233247 A · Owner: International Business Machines Corporation · Inventors: Jen, Shen; Kabelac, William J.

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Abstract From the Canadian patent

An improved servo control system for data track following of the read/write head in a magnetic recording system uses a pattern of segments of servo information slanted across the data tracks. The time of flight of the servo segment from occurrence of a reference pulse until the peak servo signal is read by the head is an indication of the position of the head in a direction perpendicular to the desired track. This time is compared with the known time of flight if the head were precisely over the centerline of the desired track and the time difference is used to generate a control signal to position the head over the track centerline. In an embodiment where each segment is slanted across …

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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 February 23, 1988. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 23, 2005.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledApril 11, 1986
GrantedFebruary 23, 1988
Term endedFebruary 23, 2005
Patent numberCA 1233247 A
Classification (IPC)G11B5/59

Timeline

Timeline From CIPO dates

1987198919911993199519971999200120032005Application filedApril 11, 1986Patent grantedFeb 23, 1988Term endedFeb 23, 2005

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