Bidirectional optical transmission system having a light-interruption detecting function
CA 2002432 C · Owner: Fujitsu Limited · Inventors: Shimizu, Kazuyoshi
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Disclosed is a bidirectional optical, transmission system for effecting bidirectional optical transmission between offices by utilizing a common optical transmission line. Each office comprising: a light transmitting unit for transmitting a light signal to another office; a light receiving unit for receiving a signal from the other office; and a light passing unit for passing the transmission signal from the light transmitting unit to the optical transmission line and for passing the receiving signal from the optical transmission line to the light receiving unit. To discriminate whether the received signal is the signal from the other office or from the same office by crosstalk through the …
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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
- Filed November 7, 1989 and granted November 30, 1993. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended November 7, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 7, 2011.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.