Direct positive films
CA 2054716 A1 · Owner: Abbruzzese, John · Inventors: Abbruzzese, John; Aguero, Adelberto; Gallo, Steven R.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Direct positive photographic films are disclosed having novel density enhancers of the formula, wherein A is oxygen or sulfur and B is selected from the group, consisting of hydrogen alkyl, haloalkyl, hydroxyalkyl, alkylamino and alkoxy. Photographic materials coated with emulsions having these density enhancers display good optical density while maintaining high speed capability.
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 April 26, 1990. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended April 26, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 26, 2012.
- 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.