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Expired Canadian patentCanada

Electrical guide for tight tolerance machining

CA 1311272 C · Owner: Digital Equipment Corporation · Inventors: Smith, Alan B.

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

Method and apparatus for determining present machining height during machining of a workpiece includes an analog resistive sensor, a discrete resistive sensor and a resistive integrity sensor. Analog sensor preferably has a plurality of resistive elements. Discrete sensor includes contact break points on resistive legs, each leg having a different resistive value to create a step-wise incremental change in resistance of discrete sensor as contacts are lapped away. Integrity sensor has resistive value in fixed relation to resistive value of discrete sensor such that ratio is indicative of integrity before machining. Invention enables use of electronic lapping guide with electrically …

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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 December 8, 1992. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended December 8, 2009.
  • 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 18, 1989
GrantedDecember 8, 1992
Term endedDecember 8, 2009
Patent numberCA 1311272 C
Classification (IPC)G01B7/00 +2 more

Timeline

Timeline From CIPO dates

1990199219941996199820002002200420062008Application filedJuly 18, 1989Patent grantedDec 8, 1992Term endedDec 8, 2009

Sources & verification

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