Focus control for optical disc system
CA 1232966 A · Owner: Philips Electronics N.V. · Inventors: Van Sluys, Robert N.J.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
PHN 10 949 15 30-5-1984, ABSTRACT:, "Apparatus for recording and/or reading information in/Prom a track of a reflecting record carrier which apparatus, comprises a focusing-control system with reduced spotoffset sensitivity.", The apparatus for recording and/or reading information in/from a track (7) of a radiation-reflecting record carrier (1) by means of a light source (4) which produces a light beam (3), an objective system (5) for focusing the light beam so as to form a light spot (V) on the record carrier depending on a control signal (Sf) a focusing-, error detection system comprising an astigmatic element (11) and four detectors (D1 to D4), comprises means (20) for deriving the …
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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
- Granted February 16, 1988. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 16, 2005.
- 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.