Weighted transducer and driving circuit with feedback
CA 2090481 C · Owner: Gottlieb, Mark · Inventors: Roche, Tom; Gottlieb, Mark
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A sound generating device which increases the effectiveness of the sound generated by mechanically coupling a weight to a piezoelectric element. This sound generating device may find particular application in a combination backup light and sound generating device utilized in an automotive vehicle. Also circuitry for, driving a piezoelectric element at its resonant frequency when the driving signal is applied to the piezoelectric element across a step-up transformer. The circuitry features a feedback signal which detects the frequency at which the piezoelectric element is vibrating. This feedback signal is then subjected to low-pass and high-pass filtering to remove any phase shifts …
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 February 21, 1992 and granted November 18, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended February 21, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by February 21, 2014.
- 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.