Data compression and decompression system with immediate dictionary updating interleaved with string search
CA 2260883 C · Owner: Unisys Corporation · Inventors: Welch, Terry A. (Deceased); Cooper, Albert B.; Welch, Theresa Raylene (Executrix, Estate Of Terry A. Welch)
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A dictionary based data compression and decompression system where in the , compressor (10), when a partial string W and a character C are matched in the dictionary (13), a new string is entered into the dictionary with C as an extension character on the string PW where P is the string corresponding to the last output compressed code signal. An update string is entered (113) into the compression dictionary for each input character that is read and matched. The updating is immediate and interleaved with the character-by-character matching of the current string. The update process continues until the longest match is found in the dictionary. The code of the longest matched string 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
- Filed July 23, 1997 and granted June 4, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended July 23, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by July 23, 2019.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
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Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.