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Expired Canadian patentCanada

Tri-state optical device

CA 1299717 C · Owner: American Telephone And Telegraph Company · Inventors: Lentine, Anthony Lodovico

CIPO record

Overview

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

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Abstract From the Canadian patent

Abstract, A tri-state optical device 400 is disclosed having photodiodes 401 and 402 with respective quantum-wells 403 and 404 in the intrinsic regions. The photodiodes are connected in series with a bipolar switch 406 and a source of electrical potential 405 for emitting a pair of optical output beams having various combinations of power levels depending on the state of the bipolar switch and the ratio of two optical control beams incident on the photodiodes. In one state of the tri-state device with the bipolar switch in a conducting state the two output beams, have complementary high and low power levels representing for example, high, and low logic levels "1" and "0". In a second state …

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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 April 28, 1992. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended April 28, 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.
FiledNovember 29, 1988
GrantedApril 28, 1992
Term endedApril 28, 2009
Patent numberCA 1299717 C
Classification (IPC)G02F3/00 +2 more

Timeline

Timeline From CIPO dates

1989199219951998200120042007Application filedNov 29, 1988Patent grantedApril 28, 1992Term endedApril 28, 2009

Sources & verification

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