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:
Dec. 17, 1991
Filed:
Apr. 23, 1990
Lawrence Terrill, Bloomington, IL (US);
Francis L Carr, Downers Grove, IL (US);
Safco Corporation, Chicago, IL (US);
Abstract
A noise immune electronic switch is connectible between a cigarette lighter socket of a vehicle and a plug-in accessory device. The electronic switch is turned on in response to the drop in B+ voltage at the lighter socket when the automobile starter is engaged for rapidly charging an integrating capacitor that is coupled to a comparator. The other comparator input is connected to a source of reference voltage. The output of the comparator, when switched, drives a transistor switch conductive to couple the B+ line between the cigarette lighter socket and an output connector. A filter passes alternator ripple voltage on the B+ line to an amplifier where the ripple is amplified and inverted. The negative half cycles of the ripple voltage charge the integrating capacitor to maintain the comparator output switched. A defeat diode is connected between the integrating capacitor and the output connector such that the capacitor cannot charge when the transistor switch is non-conductive and an accessory device is connected to the output connector. A turn-on transistor is coupled between the storage capacitor and the integrating capacitor and is turned on by the sharp drop in voltage on the B+ line when the automobile starter motor is engaged.