JPH0444994B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a fire alarm system, and particularly provides an early warning system that generates very few non-fire alarms.

``Prior Art'' Conventionally, fire alarm systems generally consist of a plurality of fire detectors that are installed in each warning area and operate at a predetermined sensitivity, and a receiver that is connected to the fire detectors via a signal line. There is. When the fire detector detects a fire, the receiver detects an operation signal and displays an alarm. Fire detectors are used that operate with a predetermined fixed detection sensitivity depending on the conditions of the place where they are installed.

"Problems to be Solved by the Invention" Such conventional fire alarm devices often cause false alarms. This is because the installation conditions of the location where the fire detector is installed are slightly different in each case, and this parameter is the cause of false alarms. Accurately knowing the installation conditions of each fire detector in advance requires time and effort. Furthermore, if a fire detector that often malfunctions after installation is to be replaced with one with lower sensitivity, it is necessary to go to the site, and replacement may be difficult or dangerous.

``Means for Solving the Problems'' The fire alarm device of the present invention uses a multi-sensitivity fire detector that outputs operating signals in response to a plurality of different detection sensitivities, and the receiver has non-fire It is activated by a switch operation when a fire alarm is confirmed, and consists of a switching means for selecting one of the plurality of signal lines connected to a multi-sensitivity fire detector, or a means for changing the conditions for determining the occurrence of a fire. It is.

"Function" Since the detection sensitivity of the fire detector or the criteria for determining the occurrence of a fire can be easily changed to suit the installation conditions, an early warning system with fewer false alarms can be provided.

"Embodiment" An embodiment of the fire alarm device of the present invention will be described based on the drawings.

FIG. 1 is a block circuit diagram showing an embodiment of the fire alarm system of the present invention, showing a receiver RG, signal lines C, L1, L2, and a multi-sensitivity fire detector.
It is composed of DE. Receiver RG is powered by E
and a fire relay with three normally open contacts rf1~3
RF, a confirmation circuit CNC that confirms the operation recovery and re-operation of the multi-sensitivity fire detector DE, an alarm ARM that displays an alarm in the event of a fire, a push button switch rc, resistors R1 and R2, and an AND circuit AND1. a switch means consisting of an AND circuit AND2, a counter CT, inverters IN1 and IN2, an AND circuit
NAND1~3, diode D1~4, normally closed contact
Relay RA with ra, relay with switching contact rb
and a switching means consisting of RB.
In addition, the fire relay RF and confirmation circuit CNC are used to activate the alarm when the multi-sensitivity fire detector DE first operates.
It constitutes a fire occurrence determination means that activates the ARM, or restores the multi-sensitivity fire detector DE from its initial activation and activates the alarm ARM again within a predetermined period of time.

FIG. 2 is a block circuit diagram showing an embodiment of the confirmation circuit CNC of the receiver RG, which includes a transistor Q1, resistors R3 to R5, two mono-multivibrators MM1 and MM2, and a normally closed contact rd. relay with
It consists of RD.

FIG. 4 is a circuit diagram showing an embodiment of the multi-sensitivity type fire detector DE, which is applied to an ion type smoke detector. The ion chamber CH1 is ionized by a radiation source and sealed, and the ion chamber CH2 is ionized in the same way and allows outside air to enter freely.
A field effect transistor FET that converts the impedance of the intermediate electrode of both ion chambers CH1 and CH2,
Transistor Q2, diodes D5, 6, resistor R
6 A constant voltage circuit consisting of a Zener diode Z1, resistors R7 to R11, a Zener diode Z2,
3. An operation signal generation circuit consisting of thyristors SCR1 and SCR2.

First, the operation of the multi-sensitivity fire detector DE will be explained. Normally, this detector DE is supplied with power from the receiver RG via the signal lines L1, C or the signal lines L2, C. This power is applied to a constant voltage circuit consisting of transistor Q2 etc. through interference prevention diodes D5 and D6, and the constant voltage generated by this constant voltage circuit is supplied to ion chamber CH1 and field effect transistor FET. . If smoke enters the ion chamber CH2 due to a fire, etc., the ion current decreases and the field effect transistor
The gate voltage of the FET rises and the source current increases. Therefore, the voltage across resistor R7 is proportional to smoke density. Since the Zener voltage of Zener diode Z2 is lower than that of Zener diode Z3, the thyristor
SCR1 becomes conductive at low smoke concentrations, ie outputs a highly sensitive operating signal. Also Sairita
SCR2 becomes conductive at higher smoke concentrations,
In other words, a low sensitivity operating signal is output.

Next, the overall system operation of a fire alarm system using such a multi-sensitivity fire detector DE will be explained.

The outputs of the counter CT of the receiver RG are initially set to Q ₀ =0 and Q ₁ =0 when the power is turned on. Therefore, since the outputs of the two NAND circuits NAND1 and NAND2 are at a high level, relays RA and RB are in a de-energized state. The switching contact rb is connected to the signal line L1 side, and the sensor DE receives power from the signal line L1 and is in a highly sensitive monitoring state. In this state, when the sensor DE outputs a high-sensitivity operating signal, the signal lines L1 and C are short-circuited with low impedance. Fire relay RF is energized and each normally open contact rf1-3 is closed. Fire relay RF maintains itself by closing normally open contact rf1, and alarms such as buzzers and indicator lights are activated by closing normally open contact rf2.
Drives ARM. By closing the normally open contact rf3, one input of the AND circuit AND1 is set to high level.

If this fire alarm is confirmed at the scene as a non-fire alarm, this means that the background noise in this monitoring area has temporarily exceeded the detection sensitivity set by the detector DE. At this time, press the push button switch.
When fc is pressed, both inputs of the AND circuit AND1 become high level, and a high level signal is output to its output. This signal is input to the counter CT via the AND circuit AND2 and counted. The output of the counter CT becomes Q ₀ = 1, Q ₁ = 0, and the relay
Energize RA. The normally closed contact ra of the relay RA is opened, and the confirmation circuit CNC is inserted between the fire relay RF and the signal line L1. Confirmation circuit CNC
As shown in Fig. 2, when the sensor DE issues an operating signal, the transistor Q1 becomes conductive and a voltage is generated across the resistor R5, which causes the mono-multivibrator MM1 to become conductive.
trigger. Mono multivibrator MM2
is triggered by the rising edge of the rectangular wave of mono multivibrator MM1, and the pulse width is T2 (T1>T
2) Outputs the rectangular wave. Relay RD is then energized by this rectangular wave output. This confirmation circuit
Figure 3 shows a time chart of voltages at various parts of the CNC. As shown in the time chart, when sensor DE operates, relay RD operates immediately and normally closed contact rd
opens, cutting off the power supply to the sensor DE and restoring it. After this recovery time T2, the sensor is activated again.
If power is supplied to DE and it operates again within the confirmation time T1-T2, mono multivibrator MM1 has already been triggered and its output remains at high level, so mono multivibrator MM2
is not triggered, relay RD is not energized, and normally closed contact rd remains closed. Then, the operating current of the fire detector DE continuously flows through the fire relay RF, energizing it, and the normally open contact RF
2 closes and drives the alarm ARM to issue a fire alarm. Confirmation circuit CNC is like this fire detector DE
This is a so-called storage circuit that confirms the recovery and re-operation of the system.

Even in this alarm operation, if it is confirmed that it is a non-fire alarm, press the push button switch rc again. As a result, the outputs of the counter CT become Q ₀ =0 and Q ₁ =1.
Relay RA is deenergized and normally closed contact ra is closed, relay
RB is energized and its switching contact rb is switched to connect to the signal line L2 side. In other words, it enters a monitoring state in which the operating signal of the low sensitivity detection of the sensor DE is directly received by the fire relay RF without going through the confirmation circuit CNC.

If a non-fire alarm is to be generated even in this monitoring state, press the pushbutton switch rc again to set the outputs of the counter CT to Q ₀ =1 and Q ₁ =1. NAND circuit NAND
Since the output of 3 becomes low level, relay RA,
Both RB become energized. That is, the sensor DE
The low sensitivity detection signal is received and further confirmed by the circuit
It enters a monitoring state via CNC to determine if a fire has occurred. In this way, by operating the push button switch rc, it is possible to switch in the order of high sensitivity detection, advanced accumulation detection, low sensitivity detection, and low sensitivity accumulation detection.

The fire alarm system of the present invention is not limited to the embodiments shown in FIGS. 1 to 4, and even when using sensors with two or more detection sensitivities, a switching means for selecting a plurality of signal lines may be provided. This can be easily implemented by setting multiple conditions sequentially in the fire occurrence determination means on the receiver side (for example, by setting the time from the initial operation of the detector DE to the time when it recovers and confirms its re-operation in stages). It is also possible to set the accumulation time in stages (so-called a method of setting the accumulation time in stages).

AND circuit of input section of pushbutton switch RC
The circuit consisting of AND1, normally open contact rf3, and resistor R2 is designed to enable the function of the pushbutton switch rc only when a fire alarm occurs. Although it is not a particularly necessary circuit for this device, it can be used by mistake during normal times. The switching means is prevented from operating when operated.
If this input section circuit is omitted, the switching means becomes ready at any time and can also be used for changing sensitivity during installation.

Further, in this embodiment, the judgment criteria are sequentially changed using a switching means consisting of a push button switch rc, a counter CT, etc., but it is also possible to use a rotary switch which also serves as the switching means.

Displaying the state of the switching means based on the output of the counter CT or the like on a display (not shown) makes the currently set judgment criteria clear and is extremely convenient.

Further, in the case of sensors DE having the same detection sensitivity, a plurality of sensors DE can be connected in parallel to the signal lines L1, L2, and C.

"Effects of the Invention" As explained above, the fire alarm system of the present invention is effective when the receiver RG
By operating a switch on the side, the criteria for determining the occurrence of a fire can be easily changed to one that suits the installation conditions, making it possible to set the monitoring state to match the installation environment, which is extremely useful for disaster prevention.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing an embodiment of the fire alarm system of the present invention, FIG. 2 is a block circuit diagram of a confirmation circuit used in the same embodiment, and FIG. 3 is a time chart showing waveforms of various parts of the confirmation circuit. FIG. 4 is a circuit diagram of a multi-sensitivity fire detector used in the above embodiment. FS...Receiver, L1, L2, C...Signal line,
DE...Multi-sensitivity fire detector, E...Power supply, RF...
...Fire relay, RA, RB, RD...Relay,
ARM...alarm, CNC...confirmation circuit, AND1,
2...AND circuit, NAND1-3...NAND circuit, CT...counter, IN1,2...inverter, R1-11...resistor, D1-6...diode, Z1-3...Zener diode, Q1, 2
...Transistor, MM1,2...Mono multivibrator, CH1,2...Ion chamber, FET...
Field effect transistor, rc...push button switch.

Claims (1)

[Claims] 1. A multi-sensitivity type fire detection system that has a detection unit that detects fire phenomena such as smoke and heat, outputs operation signals corresponding to multiple detection sensitivities, and recovers when the power is cut off. a plurality of signal lines connected to the output of the fire detector; and a plurality of signal lines connected to one end of the plurality of signal lines, the alarm being activated when a fire is determined based on the operating signal from the fire detector. In a fire alarm system comprising a fire receiver that is activated to display an alarm, the fire receiver detects the operating current of the fire detector via the signal line, and detects the operating current of the fire detector through the signal line. A fire occurrence determination system that can switch the judgment condition of activating the alarm by the operation of the alarm, or activating the alarm by temporarily restoring the fire detector from the initial operation and activating the alarm again within a predetermined time. switching means for outputting a signal indicating an operation input when a pushbutton switch or the like is operated; switching the signal line connected to the fire occurrence determining means based on the signal from the switching means; 1. A fire alarm device comprising a switching means for alternately switching judgment conditions of an occurrence judgment means. 2. The means for determining the occurrence of a fire consists of a fire relay that detects the operating current of the fire detector and drives the alarm, and a confirmation circuit that restores the activated fire detector and confirms its re-operation within a predetermined time. A fire alarm device according to claim 1. 3 The switching of the signal line by the switching means is such that the signal line connected to the fire detector is sequentially switched from the signal line to which a high-sensitivity operating signal is output to the signal line to which a low-sensitivity operating signal is output. A fire alarm device according to claim 1, characterized in that: 4. The fire alarm device according to claim 1, wherein the switch means is provided with means that functions only when a fire alarm is being issued. 5. Claim 1, characterized in that the switching means is provided with a display that displays the switching state.
Fire alarm device as described in section.