Line interface circuit
CA 2062870 C · Owner: Bell-Northern Research Ltd. · Inventors: Lee, Michael Charles Gerald
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An interface unit for interconnecting a telephone central switch to a personal computer. The interface unit receives power and data from the switch over a two wire twisted pair. The data is in a half duplex TCM (time compression multiplexed) format and is transformed into standard digital data with the logic "1" and "0" being represented by +5V and 0V respectively. The standard digital data is then arranged into 8 bit words and encoded in either an asynchronous or synchronous manner depending on the type of computer. The interface unit has a line interface circuit which provides the physical interface between the interface unit and the computer. The interface unit has a transmitter circuit …
Read the whole patent
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 March 12, 1992 and granted March 18, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 12, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 12, 2014.
- 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.