lzw patent search

[Drew Scott Daniels <umdanie8@cc.UManitoba.CA>]

Hi,
When do all the lzw related patents expire? I've heard different stories
and am confused by all the different patents that seem to exist for lzw.
I also am unsure as to how to search for information about each of the lzw
patents.

http://www.google.ca/search?q=cache:gHNrsOfbP7UC:www.unisys.com/about__unisys/lzw/+lzw&hl=en&ie=UTF-8
says:
including United States Patent No. 4,558,302, Japanese Patent Numbers
2,123,602 and 2,610,084, and patents in Canada, France, Germany, Italy and
the United Kingdom.

and:
Welch Patent Licensing Department; Unisys Corporation; Mail Stop E8-114;
Unisys Way, Blue Bell, PA 19424. Via the Internet, send E-mail to
LZW_INFO@UNISYS.COM. Via facsimile, send inquiries to Welch
Patent Licensing Department at 215-986-3090

Thanks

     Drew Daniels