Twisted nematic liquid crystal display device
CA 2002427 C · Owner: International Business Machines Corporation · Inventors: Suzuki, Shunji
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The disclosure describes the provision of a normally black type twisted nematic liquid crystal display device which with variation in the visual angle, variation in contrast and background color is small. In effecting this the product of the thickness d of the liquid crystal layer between electrodes and the double refraction index of the liquid crystal layer concerned lies between 1.4 µm and 1.7 µm.
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 November 7, 1989 and granted January 11, 1994. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended November 7, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 7, 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.