Optical card
CA 2221723 C · Owner: Dai Nippon Printing Co. Ltd. · Inventors: Azuma, Yoshihiro; Takei, Jiro
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
This invention relates to an optical card having a preformat portion comprising a low reflectance area having an excellent contrast to high reflectance area. An optical card original plate whose portions corresponding to preformat portions 4, 5 of an optical card 1 each have a stereostructure of an inverted pyramidal shape is prepared. An optical card is duplicated from this optical card original plate. The stereostructure in an inverted pyramidal shape can be formed by the anisotropic etching of a single crystal substrate. An original plate free from defects and surface roughnesses and ensuring a sufficiently low reflectance is obtained. An optical card produced from this original plate …
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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 March 21, 1997 and granted August 29, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 21, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 21, 2019.
- 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.