Self-checking circuit arrangement for operation of a searchlight signal
CA 2042634 C · Owner: Union Switch & Signal Inc. · Inventors: Darrow, John O. G.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
TITLE:, Self-Checking Circuit Arrangement for Operation of a Searchlight Signal, ABSTRACT The circuit arrangement of this invention includes a signal searchlight wherein the lamp is in an electrical series circuit with interlock contact switches. The switches interlock the display color lens such as yellow and green to control the electrical energization of the signal circuit. Logic control switching devices in a remote wayside control box supply signals through a cable to operate a bipolar device to selectively display the desired color.
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 May 15, 1991 and granted November 22, 1994. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended May 15, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by May 15, 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.