JPS6367233B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a fire alarm system equipped with a smoke detector.

Prior Art As a conventional fire alarm device, one is known that is provided with a switching circuit that generates a pulse according to the operation of a smoke detector that detects smoke, and turns the fire alarm circuit on and off every time this pulse is generated. (Reference: Japanese Patent Publication No. 56-31028 by the applicant).

However, in the conventional type described above, even a small amount of smoke such as cigarette smoke causes the fire alarm circuit to turn on and off, making it impossible to distinguish it from smoke caused by a fire.
Therefore, there was a problem of malfunction.

Purpose of the Invention In view of the problems with the conventional type described above, the purpose of the present invention is to operate a fire alarm circuit only when a predetermined number (predetermined time) of output pulses from a pulse generation switching circuit are generated.
To prevent malfunction of a fire alarm circuit by making it possible to distinguish between temporary smoke and fire smoke.

Structure of the Invention According to the present invention, in order to achieve the above-mentioned object,
A resistor connected to one end of the DC power source, a smoke detector connected between the resistor and the other end of the DC power source, and a switch inserted into a circuit configured by the smoke detector and the resistor. a pulse generation switching circuit for controlling the switch on and off by identifying the DC voltage generated across the resistor in accordance with the operation of the smoke detector; and on and off control using the output pulse of the switching circuit. In a fire alarm device having a fire alarm circuit, an integrating circuit is provided between an output of the switching circuit and an input of the fire alarm circuit, and the output pulse is continuously transmitted. There is provided a fire alarm device characterized in that the fire alarm circuit is activated when a predetermined number of fire alarms occur.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the figure, 1 is, for example, a 30V DC power supply, to which a resistor 2 and a smoke detector 3 are connected in series. The smoke detector 3 is, for example, an ion type smoke detector, and becomes conductive when smoke is detected,
On the other hand, it becomes non-conducting when no smoke is detected.

A switch 4 is inserted into the circuit constituted by the resistor 2 and the smoke detector 3, and the switch 4 is turned on and off by a pulse generation switching circuit 5. That is, the switch 4 and the coil 57 of the pulse generation switching circuit 5 constitute one relay circuit.

The pulse generation switching circuit 5 also includes input resistors 51 and 52 and reference voltage generation resistors 53 and 5.
4, a comparison circuit 55 that compares the potential of the node N ₁ and the potential of the node N ₂ , and a transistor 56 for driving the relay coil 57 .

Reference numeral 6 denotes an integrating circuit for integrating the output pulses of the pulse generation switching circuit 5, and is constituted by a resistor 61 and a capacitor 62. In other words,
The integrating circuit 6 is a switching circuit 5 for pulse generation.
When a predetermined number of consecutive output pulses (a predetermined time) are received, the output (node N ₄ ) is set to high level. Note that the above-mentioned predetermined number of pulses is adjusted by the values of the resistor 61 and capacitor 62.

7 is a fire alarm circuit, which includes a thyristor 71;
It is composed of a relay circuit 72 and a display lamp 73. The thyristor 71 is turned on by the high level output of the integrating circuit 6, and remains on thereafter. As a result, the relay circuit 72 is driven and the display lamp 73 is turned on.

Next, the operation of the illustrated circuit will be explained.

First, a case where the smoke detector 3 does not detect smoke will be described. In this case, the smoke detector 3 maintains a non-conducting state, so the potential of the node _N1 of the pulse generation switching circuit 5 is at a high level (approximately
30V), and as a result, the output of the comparison circuit 55 (node N ₃ ) becomes low level. Therefore, transistor 56 is held off, the relay circuit is not driven, and switch 4 is therefore also held closed. At this time, the subsequent integration circuit 6 and fire alarm circuit 7 do not operate.

Next, a case where the smoke detector 3 detects smoke will be described. In this case, the smoke detector 3 that has detected smoke becomes conductive, and the potential of the node _N1 of the pulse generation switching circuit 5 becomes a low level (almost 0V), and as a result, the output of the comparison circuit 55 becomes a high level. . Therefore, the transistor 56 is turned on and the relay circuit is driven, so that the switch 4 is opened. When the switch 4 is opened in this way, the potential of the node _N1 rises again, and therefore the output potential of the comparator circuit 55 falls again. As a result, the transistor 56 is turned off and the relay circuit is driven. stops. In other words, switch 4
is controlled to turn on and off at predetermined intervals, and the output node N ₃ of the comparison circuit 55 sends out a pulse signal to the integration circuit 6.

The integration circuit 6 integrates the output pulses of the above-mentioned comparison circuit 55, but only when a predetermined number of pulses are generated in succession, the potential of the node _N4 turns on the thyristor 71 of the fire alarm circuit 7. This is the level where you can do it. Therefore, when temporarily generated smoke such as cigarette smoke is detected, the level of node _N4 does not become sufficiently high, and therefore, the fire alarm circuit 7 does not operate. On the other hand, when smoke generated for a certain period of time or more is detected, such as in a fire, the level of node _N4 becomes sufficiently high, and therefore, the fire alarm circuit 7 is activated.

Effects of the Invention As explained above, according to the present invention, since an integrating circuit is provided to integrate the output pulses of the pulse generation switching circuit, it is possible to distinguish between temporary smoke and fire smoke. Fire alarm circuit 7
does not malfunction.

[Brief explanation of drawings]

The attached figure is a circuit diagram showing one embodiment of the fire alarm device according to the present invention. 1: DC power supply, 2: Resistor, 3: Smoke detector, 4:
Switch, 5: Switching circuit for pulse generation,
6: Integral circuit, 7: Fire alarm circuit.

Claims (1)

[Claims] 1 A resistor connected to one end of the DC power supply, a smoke detector connected between the resistor and the other end of the DC power supply, and a switch inserted into a circuit configured by the smoke detector and the resistor. , a pulse generation switching circuit that identifies the DC voltage generated across the resistor according to the operation of the smoke detector and controls the switch on and off; and a pulse generation switching circuit that controls the switch on and off according to the operation of the smoke detector; In a fire alarm device equipped with a controlled fire alarm circuit, an integrating circuit for integrating output pulses of the switching circuit is provided between an output of the switching circuit and an input of the fire alarm circuit, and the output pulses are continuous. 1. A fire alarm device, characterized in that said fire alarm circuit is activated when a predetermined number of fire alarms occur.