Reflection type overhead projector
CA 2047772 A1 · Owner: Kawahara, Yukio · Inventors: Isobe, Toshiya; Kajikawa, Mitsugi; Yonemitsu, Toshihiro
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A mirror Fresnel lens (12) is disposed on a base (11), on which a liquid crystal display (18) is mounted. The liquid crystal display (18) is provided with a polarization plate (24) only in the mirror Fresnel lens (12) side. Light from a light source (15) passes through the liquid crystal display (18), is reflected by the mirror Fresnel lens (12), again passes through the liquid crystal display (18), is converged by a projection lens 16 and reflected by the mirror (17) and eventually arrives at a screen (20). A separated polarization plate (25) is provided in a manner to overlap with the projection lens 16. The separated polarization plate (25) is paired with the polarization plate (24).
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 July 24, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended July 24, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by July 24, 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.