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:
Jan. 11, 1977
Filed:
Jul. 19, 1973
Matthew J Dunphy, Braintree, MA (US);
Pyrotector, Incorporated, Hingham, MA (US);
Abstract
A fire detection system of the type utilizing an optical detector with discriminating photo-cells connected in series to form a voltage divider, with the rise in voltage at the junction of the photo-cells being utilized as the input to an amplifier to energize an alarm or actuate an extinguishing system, in which the ground wire to the remote optical detectors is also used as the ground wire between the amplifier and the actuating means for the alarm or the extinguishing system, whereby a break in the ground wire, which causes a rise in voltage at the junction, is prevented from causing a false alarm, since said break also breaks the circuit between the amplifier and the actuating means.