Photographic products and processes
CA 1325639 C · Owner: Polaroid Corporation · Inventors: Waller, David P.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Abstract of the Disclosure This invention relates to diffusion transfer photographic processes adapted to be performed in the presence of ambient light and to diffusion transfer products useful in such processes wherein a substantial increase in opacification in the red and near infrared region of the visible spectrum and a substantial increase in opacification in the blue and green region is achieved by employing certain alkyl-substituted phenanthrol/carboxynaphthol phthaleins as the lightabsorbing, pH-sensitive optical filter agent for the longer wavelength region of the visible spectrum.
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
- Granted December 28, 1993. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended December 28, 2010.
- 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.