FIRE ALARMING SYSTEM

• US 3,778,796 A
• Filed: 03/02/1971
• Issued: 12/11/1973
• Est. Priority Date: 03/31/1970
• Status: Expired due to Term

• Current Assignee: Yukio Honda
• Original Assignee: Yukio Honda
• Inventors: Honda, Yukio
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Myer, Daniel
• Application Number:
  US05/120,178
• Time in Patent Office: 1,015 Days
• Field of Search: 340/237S,184,416,216
• US Class Current: 340/517
• CPC Class Codes: G08B 17/00 Fire alarms; Alarms responsive to explosion
• CPC Class Codes: G08B 17/11 using an ionisation chamber for detecting smoke or gas
• CPC Class Codes: G08B 25/04 using a single signalling line, e.g. in a closed loop

Abstract

A fire alarm system having a plurality of detectors connected to a pair of conductors, a receiver and a power supply connected to said conductors and an alarm connected to the power supply and said conductors so that an alarm is sounded upon activation of a detector, each detector upon activation producing a preselected AC signal for transmission to the receiver and the receiver includes band pass filters activated by particular frequencies and having associated indicating means so that the activated detector and therefore the location of the fire or smoke can be immediately determined.

Claims

1. A fire alarm system comprising a plurality of fire detecting units for sensing heat or smoke, a receiving station including a direct current power supply, a pair of conductors connected at one end to said power supply, connections between each detecting unit and said conductors, each of said units including an AC generating device having a preselected frequency, heat or smoke detecting means electrically coupled with said generating means and with said conductors, and means including DC blocking means coupling said generator to said conductors whereby actuation of one of said detecting means at least partially shunts said conductors to increase the flow of current therethrough and causes an AC signal to be applied to said conductors, and said receiving means includes means responsive to an increase in current in said conductors to produce an alarm, frequency discriminating means responsive to said AC signals and a plurality of indicating means interconnected with said discriminating means, each of said indicating means being selectively activated by said discriminating means upon activation of one of said detecting units to identify the location of the detecting unit producing an alarm.