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:
May. 21, 1991
Filed:
Oct. 02, 1990
Sadataka Yuchi, Kanagawa, JP;
Hochiki Corporation, Tokyo, JP;
Abstract
In a fire alarm system including a plurality of addressable detectors connected to a main circuit extended from a central receiving unit, any alarming detector is discriminated and indicated in accordance with its address on the receiving unit side. In this system, one of the addressable detectors is assigned as a group master detector to each of areas under surveillance and the other detectors within the same area under surveillance have no addressing function. The unaddressable detectors are dependently connected to the group addressable detector within the same area under surveillance. Each of the addressable detectors includes a current limiting circuit which upon alarming limits the amount of current supplied to the main circuit to which the addressable detector is connected, and a changeover circuit for changing over the limited current value by the current limiting circuit to a lower value in response to an address-designated control signal supplied from the receiving unit when the number of alarming detectors exceeds a predetermined number.