Electrothermal color-varying instrument
CA 2050233 C · Owner: Nakagawa, Tanehiro · Inventors: Ono, Yoshiaki; Yamaguchi, Takeo; Tomatsu, Tsutomu
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An electrothermal color-varying instrument for inducing color change. in a thermal color-varying layer provided in a toy, a picture book, a teaching aid a, writing board has an electrothermal heat-generating element serving as a heat source which is composed of a thermistor which has:, (i) a positive temperature coefficient on the electrical resistance within a temperature range from 25°C to 70°C;, (ii) a volume resistivity at 25°C (p25) within a range of 9.8 x 10 -3 to 2.97 x 10 5 .OMEGA.~cm; and (iii) a ratio (p70/p25) of the volume, resistivity at 70°C to that at 25°C within a range of ~ (p70/p25) ~ 400; and, which is adapted to generate heat under the application of a voltage in a range …
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 August 29, 1991 and granted December 12, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended August 29, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 29, 2013.
- 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.