JPS6213196Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a fire alarm system.

The conventional fire alarm system, as shown in Figure 1,
The DC power supply 1, the reception relay 2, the normally open relay contact 3 of the reception relay 2, and the resistor 4 are connected in a loop, and the connection point of the reception relay 2 and the normally open relay contact 3 is connected to the negative side of the DC power supply 1, respectively. Terminals 5 and 6 are provided to constitute a receiver body, and a plurality of smoke detectors,' are connected between the terminals 5 and 6.

Next, this operation will be explained. When one smoke detector is activated and conducts, an exciting current flows through the receiving relay 2, the normally open relay contact 3 is closed, and the receiving relay 2 enters a self-holding state.

However, in such a conventional fire alarm device, when the receiving relay 2 enters the self-holding state, the terminals 5 and 6
The voltage between the two smoke detectors drops (the voltage is applied enough to light up the display light emitting diode built into the smoke detector), and other smoke detectors after the second one become inoperable. Even if smoke detectors were installed, they could only provide a regional warning function. In addition, in this kind of fire alarm system, multiple smoke detectors are connected in parallel between two lines drawn out from the receiver body, so the smoke detectors are close to the receiver body, If the smoke detector is located far away from the receiver, there will be a difference in the voltage applied to the smoke detector due to the voltage drop in the two lines, making it impossible for the smoke detector to operate in the same way. However, there was a problem in that the brightness of the display light emitting diodes varied.

Therefore, the purpose of this invention is that even if one fire detector operates and the voltage between the two lines fails, the remaining fire detectors will operate in the same way as if they were operated first. To provide a fire alarm device which can be operated in a similar manner and can keep the brightness of a display light emitting diode constant regardless of the wiring distance from a receiver main body.

An embodiment of this invention is shown in FIG. That is, in this fire alarm system, one end of the receiving relay 8, 8' is connected to the positive side of the DC power source 7, and the receiving relay is connected between the other end of the receiving relay 8, 8' and the negative side of the DC power source 7. Normally open relay contacts 9, 9' for self-holding of the receiving relays 8, 8' are connected, and the anodes of diodes 10, 10' are connected to the other ends of the receiving relays 8, 8'. The normally open relay contacts 11 and 11' of the receiving relays 8 and 8' are connected between the cathodes of the diodes 10 and 10' and the negative side of the DC power supply 7, respectively. Terminals 12, 13, 13' are provided to constitute the receiver body, while thyristors 14,
A constant current diode 15, a light emitting diode 16, and a resistor 17 are connected in series with their polarities aligned, and a resistor 18 is connected in parallel to the series circuit of the light emitting diode 16 and resistor 17, and the anode side and cathode side of this circuit are connected to the terminal 12. , 13, and detects smoke to switch the thyristor 14 from a cutoff state to a conduction state.

Next, the operation of this embodiment will be explained.
When the smoke detection circuit 19 of one smoke sensor body detects smoke, the thyristor 14 becomes conductive. As a result, a constant excitation current i defined by the constant current diode 15 flows to the receiving relay 8, the normally open relay contacts 9 and 11 are closed, and the receiving relay 8 enters the self-holding state, and the main body of the smoke detector, ' is continuously supplied with power, and the second and subsequent smoke detector bodies' remain in an operable state.

As described above, the fire alarm system of this invention includes a DC power source, a receiving relay whose one end is connected to the positive side of the DC power source, and a receiving relay connected between the other end of the receiving relay and the negative side of the DC power source. a first normally open relay contact of the receiving relay, a diode having an anode connected to the other end of the receiving relay, and a first normally open relay contact of the receiving relay connected between the positive side of the DC power source and the cathode of the diode. a receiver main body having two normally open relay contacts, a series circuit of a display light emitting diode, a switch element, and a constant current element connected between the cathode of the diode and the negative side of the DC power supply, and a series circuit of a switch element and a constant current element; and a fire detection circuit that switches the switch element from off to on. Even when the fire alarm goes down, the remaining fire detectors can operate in the same way as the first one, and the light emitting diode for display on each fire detector can be used regardless of the wiring distance from the receiver. This has the effect of making the brightness uniform.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional fire alarm system, FIG. 2A is a block diagram of a fire alarm system according to an embodiment of this invention, and FIG. 2B is a circuit diagram of its essential parts. 7... DC power supply, 8... Receiving relay, 9... Normally open relay contact, 10... Diode, 11... Normally open relay contact, 14... Thyristor, 15... Constant current diode, 16... Light emitting diode , 19
...Smoke detection circuit.

Claims (1)

[Scope of utility model claims] a DC power supply; a reception relay having one end connected to the positive side of the DC power supply; and a first normally open relay contact of the reception relay connected between the other end of the reception relay and the negative side of the DC power supply. , a receiver body having a diode having an anode connected to the other end of the receiving relay, and a second normally open relay contact of the receiving relay connected between the positive side of the DC power supply and the cathode of the diode; , a series circuit of an indicator light emitting diode, a switch element, and a constant current element connected between the cathode of the diode and the negative side of the DC power supply, and a fire detection device that detects a fire and switches the switch element from OFF to ON. A fire alarm device comprising a plurality of fire detector bodies each having a circuit.