Variable density light control apparatus and method
CA 2000939 A1 · Owner: Fergason, James L. · Inventors: Fergason, James L.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A controllable liquid crystal polarizer has nematic liquid crystal and pleochroic dye in plural parallel, elongate, volumes in a sheet-like containment medium. Polarization effectiveness is variable as a function of electric field. A method of making the polarizer includes continuously forming a sheet-like film of a containment medium having a plurality of volumes of liquid crystal and pleochroic dye therein and, during curing of the film, stretching it to elongate the volumes. A variable density light control apparatus includes plural polarizers, at least two of which are at least partially crossed, and at least one of the polarizers being variable to the extent that it polarizes light as …
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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 October 18, 1989. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended October 18, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by October 18, 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.