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Expired Canadian patentCanada

Nondestructive readout of a latent electrostatic image formed on an insulating material

CA 1295655 C · Owner: Kamieniecki, Emil · Inventors: Goldfarb, William C.; Kamieniecki, Emil

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Abstract From the Canadian patent

A method and apparatus are described for the nondestructive readout of a latent electrostatic image formed on a sheet or layer of insulating material. A sheet or layer of semiconductor material is disposed in relatively close proximity to the insulating material. A latent electrostatic image formed on the insulating material (by any known means) causes a surface depletion layer to be produced by induction at the surface of the semiconductor material. The location and distribution of the accumulated charges on the semiconductor material are read out as analog electrical signals corresponding to the AC surface photovoltage induced on the semiconductor material as the semiconductor material is …

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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 11, 1992. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 11, 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.
FiledMay 4, 1988
GrantedFebruary 11, 1992
Term endedFebruary 11, 2009
Patent numberCA 1295655 C
Classification (IPC)G01T1/24 +2 more

Timeline

Timeline From CIPO dates

1989199219951998200120042007Application filedMay 4, 1988Patent grantedFeb 11, 1992Term endedFeb 11, 2009

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