JPS59214997A - Fire alarm - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

2. Description of the Related Art Conventionally, it has been known to provide a fire detector that is activated when the smoke concentration or temperature due to a fire reaches a predetermined value, and to issue a fire alarm by the operation of this fire detector. However, such fire alarm devices often generate false alarms due to temporary changes in physical quantities caused by cigarette smoke or air conditioning.

This invention provides an alarm when at least two fire detectors continue to operate for a predetermined period of time, or when a single fire detector operates and the physical quantity of smoke, heat, gas, etc. due to the fire increases significantly. Furthermore, the larger the physical quantity of smoke, heat, gas, etc., the earlier the alarm is generated.

Next, an embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing the configuration of the fire alarm system of the present invention, and FIGS. 2 and 3 are time charts for explaining the operation of the system shown in FIG. 1.

In Figure 1, a plurality of fire detectors -Dn are connected to the track re2 extending from the receiver R, and each of the fire detectors D1 to l-)+1 detects smoke, heat, gas, etc. a sensor 1; an amplifier 2 that amplifies the output of the sensor 1;
A threshold circuit 3 that generates an output when the output of the amplifier 2 reaches a predetermined value or more, a pulse generator 4 that generates a pulse according to the output value of the threshold circuit 3, and an output r of the pulse generator 4.
(Basically, it is composed of a transistor Tr+ that performs a switching operation between the line -e31.Ih via a resistor r1.

The receiver R also includes a power source E, a resistor r2 inserted in series between the power source E and the line 81, and a transistor Tr2 that becomes conductive when a current of a predetermined value or more flows through the resistor r2.
A counter 5 that counts the operation signal of this transistor Tr2 and generates an output when a predetermined number of pulses or more is counted; a reset pulse generator 6 that resets the counter 5 at regular intervals; and a reset pulse generator 6 that is driven by the output of the counter 5. Each of the alarm generators 7 is equipped with an alarm generator 7. Note that the counter 5 can also be replaced by an integrating circuit.

In normal fire monitoring status 1, fire detectors D1 to D
The output of the n sensor 1 never exceeds the threshold of the threshold circuit 3, so there is no pulse output from the pulse generator 4.

When a fire occurs, for example, as shown in Figure 2, the fire detector D
1 at time t1, and fire detector Dn at time t2.
When the pulse generator 3 generates pulses with periods TI and T2 as shown in FIG. 2 d+ and d2, each sensor D1 . The transistor Trx of Dn is turned on at this pulse period, and a pulse is sent to the receiver R via the resistor r1 on the lines -el and -ez.

In the receiver R, two activated fire detectors Dl,
The transistor Tr2 is turned on in synchronization with each pulse of Dn, and this pulse is applied to the counter 5. Note that the counter 5 is assumed to generate an output by inputting, for example, five pulses, and the reset pulse generator 6 is reset at a predetermined period T3.
Assuming that a reset pulse as shown in FIG. 2P is applied to the counter 5, the counter 5 generates an output at time t3, as shown in FIG. 2k, and is applied to the alarm generator 7.

If the pulse periods T, , T2 of each fire detector D+, Dn are set to vary according to smoke concentration, temperature, etc., the larger these physical quantities become, the earlier the alarm will be generated. 1. If the generation of smoke, heat, etc. is temporary, the pulse output from the pulse generator 4 is immediately stopped, and no alarm is generated.

1, if the operation of a single fire detector D1 has a pulse period of 1゛1 as shown in Figure 2 d+,
Since only 2 to 3 pulses are input to the counter 5 within the period T3 of the reset pulse, no alarm is generated.

Next, due to the operation of 11 fire detectors IJ, a fire occurred in the school.
FIG. 3 shows the operation when the pulse period of the pulse generator 4 of the detector D+ is greatly increased. Yes, there is. At this time, the pulse generator 4 generates a pulse as indicated by d+ in FIG. to drive.

As mentioned above, the fire alarm device of this invention is capable of preventing smoke.

Even if the level of heat, etc. is relatively low, if two or more fire detectors are activated, an alarm will be issued after a predetermined time, and if there is a sudden increase in smoke, heat, etc., an alarm will be issued early, so it is reliable in the event of a fire. The present invention provides a highly reliable fire alarm system that can issue a fire alarm quickly and without causing false alarms due to cigarette smoke or the like.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the fire alarm system of the present invention, and FIGS. 2 and 3 are time charts for explaining the operation of FIG. 1, respectively. , Dt-]Jn...Fire detector, R...Receiver, 1
...Sensor, 3...Threshold circuit, 4...Pulse generator, 5...Counter, 6...Reset pulse generator, 7...Alarm generator, E...Power supply Patent applicant Nitsukun Co., Ltd.

Claims (1)

[Claims] A fire detector having a pulse generator that starts operating when detecting a predetermined value or more of a physical quantity such as smoke, heat, gas, etc. and whose pulse period changes according to a change in the physical quantity, and a plurality of such fire detectors. A counter that is connected via a connected signal line and counts the 7S) responses of the fire detector, and a pulse generator that resets the counter at regular intervals, and is controlled by the output of the counter. and a receiver having an alarm generator, wherein the counter generates an output when a predetermined number or more of pulses are counted within a predetermined period of time.
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