Selective test circuit for fire detectors

• US 4,489,312 A
• Filed: 04/14/1982
• Issued: 12/18/1984
• Est. Priority Date: 04/15/1981
• Status: Expired due to Term

• Current Assignee: Nittan Co. Ltd. (Old) (Secom Company Limited)
• Original Assignee: Nittan Co. Ltd. (Old) (Secom Company Limited)
• Inventors: Yoshizaki, Yukio
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US06/368,224
• Time in Patent Office: 979 Days
• Field of Search: 340/514-516, 340/518, 340/500, 340/501, 340/506-509, 340/588, 340/589, 340/825.54, 340/825.06-825.12, 169/23, 324/158 F, 324/158 R
• US Class Current: 340/514
• CPC Class Codes: G08B 29/145 of fire detection circuits

Abstract

A circuit for selectively or extractively testing a fire detector among a plurality of fire detectors which are connected between an alarming line extending from the section relay of a receiving unit and a common line is disclosed. An inherent address code is allotted to each fire detector. When an address signal transmitted through the alarming line coincides with the allotted inherent address code, a coincidence signal is produced and in response to said coincidence signal a test voltage is generated for each fire detector.

Claims

1. A circuit for selectively testing detectors connected between one of a plurality of alarming lines each extending from a section relay of a receiving unit and a common line comprising:

an address-signal-sensing circuit for producing a coincidence signal when coincidence is sensed between an address signal transmitted through the alarming line and the inherent address code allotted to each fire detector beforehand;

a test-voltage-generating circuit for generating a test voltage to be applied to each fire detector in response to said coincidence signal;

a serial connection of a first Zenner diode and a condenser connected between the alarming line and the common line; and

means for generating a resetting signal to reset the address-signal-sensing circuit and the test-voltage-generating circuit when the alarming line voltage is in excess of a predetermined value;

whereby the condenser is charged at a voltage exceeding a predetermined value and, at the same time, resets the address-signal-sensing circuit and the test-voltage-generating circuit; and

the voltage charged on the condenser acts as the power source for actuating the address-signal-sensing circuit and the test-voltage-generating circuit.

2. A circuit for selectively testing fire detectors as recited in claim 1, wherein the means for generating the resetting signal is comprised of a third Zenner diode.

3. A circuit for selectively testing fire detectors as recited in claim 1 or claim 2, which is further provided with means for producing detector-operation signal upon actuation of one of the section relays of the receiving unit;

means for producing a finish signal when transmission of the address signal finishes; and

a non-operation sensing circuit for producing a detector non-operation signal after receiving the finish signal and the detector-operation signal provided that no detector-operation signal is further received after transmission of the address signal has finished.

4. A circuit for selectively testing fire detectors as recited in claim 3, wherein a display device is provided for indicating the address code selectively sent forth in accordance with the detector non-operation sensing signal.