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Expired Canadian patentCanada

Flaw detection method using microwaves

CA 1216042 A · Owner: Ahlstrom, (A.) Osakeyhtio · Inventors: Heikkila, Sakari; Tiuri, Martti

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Abstract From the Canadian patent

A method and an apparatus for detection of flaws in lumber is provided, in which the lumber is subjected to microwave radiation of equal intensity in turns simultaneously from two microwave radiation means in phase opposition and from an intermediate microwave radiation means and between the turns from none of said microwave radiation means. The microwave radiation transmitted through the lumber is measured and the level of the measured signals in pulse form is adjusted in such a way that the mean value of the pulse train equals a reference value. The level of the pulse train when no radiation is transmitted is adjusted to zero and the level of the pulses when said two microwave radiation …

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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 30, 1986. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended December 30, 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.
FiledJanuary 25, 1984
GrantedDecember 30, 1986
Term endedDecember 30, 2003
Patent numberCA 1216042 A
Classification (IPC)G01R27/04 +2 more

Timeline

Timeline From CIPO dates

1985198719891991199319951997199920012003Application filedJan 25, 1984Patent grantedDec 30, 1986Term endedDec 30, 2003

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