The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 15, 1994
Filed:
Mar. 10, 1992
Jean-Marie Pierret, Paris, FR;
Didier Canitrot, Saint-Maur des Fosses, FR;
Valeo Equipements Electriques Moteur, Creteil, FR;
Abstract
A circuit for detecting the state of a switch, in particular the state of a key contact for activating a regulator circuit for regulating the voltage at which a battery is charged by an alternator, in which a first terminal of the key switch is connected to a DC source and a second terminal of the key switch is connected to the regulator circuit via a load such as a warning lamp, said load being switched ON and OFF by means of a component having a voltage drop. The detection circuit is wherein it comprises amplifier means receiving a reference voltage on a first terminal, and on a second terminal the voltage present on a terminal of the load opposite from its terminal connected to the key switch, the amplifier means being designed to regulate the voltage drop to the value of the reference voltage so long as the key switch and the component having the voltage drop are conductive, and including means for generating a first signal on a key switch state detection output whenever said voltage present on the terminal is less than the reference voltage and for generating a second signal on said detection output whenever said voltage present on the terminal is greater than the reference voltage or whenever said amplifier means is regulating.