Method of and an apparatus for producing a required visual signal for direct observation from a first source of light in the presence of a second source of light
CA 2000317 A1 · Owner: Shanks, Ian Alexander · Inventors: Shanks, Ian Alexander
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A required visual signal for direct observation is produced from a first source of light in the presence of a second source of light, such as ambient light. Light is transmitted from the first source to a defined surface or defined region distant from the first source. A means for modulating light is operated between at least a first mode and a second mode. This operation is synchronised with a varying of the intensity of at least one of the sources of light at or above a given frequency equal to or greater than the critical fusion frequency for the size and luminance of the required visual signal. When the modulating means is in the first mode, this allows the required visual signal to be …
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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 October 6, 1989. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended October 6, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by October 6, 2011.
- 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
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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.