Chordal keyboard method and apparatus
CA 2101552 C · Owner: Walker-Estes Corporation · Inventors: Estes, Mark D.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A chordal keyboard method and apparatus for generating a key code using a plurality of keys (301) coupled to a controller (302) with a first and second set of registers (303, 304). A user depresses (201) at least one of the keys (301). The controller (302) detects (202) which of the keys, (301) are in a depressed position and which of the keys (301) are released from the depressed position. The controller (302) sets (203) in the first and the second set of registers (303, 304), bit locations of respective depressed keys, and clears in the second set of registers (304) bit locations of respective released keys. When the controller (302) detects (207) that all keys (301) are in a released …
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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 April 17, 1992 and granted May 8, 2001. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended April 17, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 17, 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.