Progressive addition lens
CA 1190074 A · Owner: Polycore Optical Pte. Ltd. · Inventors: Van Ligten, Raoul F.; Kee, Yeo K.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
PROGRESSIVE ADDITION LENS_, ABSTRACT, A progressive addition lens is provided having a wide transition corridor and an improved balance between astigmatism and distortion in the field of peripheral vision to provide a wide, distortion-free clear view. This is achieved by employing a cosine function in blending the transition corridor with the peripheral area.
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 July 9, 1985. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended July 9, 2002.
- 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.