JPH01287799A - Fire alarm device - Google Patents

Abstract

PURPOSE:To secure information transmission between a receiver and a sensor when a fire is detected by switching the limit value of a current limiting circuit to a specific value below, for example, a stationary monitor current when a current limitation control signal from the receiver is discriminated and received by the sensor which is in a nonalarm state. CONSTITUTION:When the receiver 1 decides that the number of alarming sensors reaches a specific value, the address of a sensor which is not in an alarming state is specified and the current limitation signal is sent out. In the sensor which discriminates and receives the current limitation control signal, a current limiting circuit 18 which limits a fire alarming current to a constant current, e.g. a current value for turning on a switching means 22 such as SCR provided to a fire detection part 4 switches the current to a lower limit value. Therefore, even if sensors which exceed the specific number alarm, the line current from the receiver 1 to sensors 3A-3N does not increase any more and a drop in sensor supply voltage due to line resistance is suppressed to a specific value. Consequently, the information transmitting function between the sensors 3A-3N which are connected to the same line and the receiver 1 is secured.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention identifies and displays the area where a fire has occurred by connecting a plurality of sensors each having a unique address between power and signal lines drawn out from a receiver. This invention relates to fire alarm equipment.

[Prior Art] Conventionally, as this type of fire alarm device, the one shown in FIG. 5, for example, is known.

In FIG. 5, reference numeral 1 denotes a receiver, and a plurality of sensors 3a to 3n each having a unique address are connected between power supply signal lines 2a and 2b drawn out from the receiver 1.

The detectors 3a to 3n are equipped with a fire detection section 4 in the detector body that triggers the SCR and sends an alarm current when a fire is detected.
On the sensor base side, there is a current detection circuit 5 that detects the alarm current of the fire detection section 40, and a receiver that transmits fire detection information together with unique address information from an address setting circuit 7 when receiving the detection output of the current detection circuit 5. A transmission circuit 6 is provided to send out a signal to the current detection circuit 1, and an L
An alarm indicator light 8 using an ED or the like is connected.

Therefore, for example, if the fire detection section 4 of the sensor 3a is activated due to fire detection and an alarm current flows due to the trigger of the SCR, the alarm indicator light 8 lights up and the current detection circuit 5 generates a detection output. A transmission signal having a frame structure including fire detection information and unique address information is sent from the transmission circuit 6 to the receiver 1. The receiver 1 that receives the signal from the sensor 3a displays a fire alarm based on the fire information in the transmitted signal, and also decodes the unique address information to determine the area where the fire occurred, for example, the sensor address. indicate.

[Problems to be Solved by the Invention] However, in such a conventional fire alarm device, when multiple sensors connected between the same power supply signal line are activated at the same time, the alarm cannot be detected. The current flowing through the power/signal line increases depending on the number of detectors, and the voltage drop due to the line resistance reduces the voltage supplied to the sensor.

Therefore, the clock pulse voltage for transmitting the detection information to the receiver may become insufficient, and there is a fear that transmission may become impossible.

[Means for Solving the Problems] The present invention has been made in view of such conventional problems, and it is possible to always receive stable reception without increasing the line current when the number of sensor alarms exceeds a predetermined number. An object of the present invention is to provide a fire alarm system that can guarantee information transmission between a fire alarm and a detector.

In order to achieve this object, the present invention connects a plurality of sensors with unique addresses between the power supply and signal lines drawn out from the receiver, and each of the sensors maintains continuity when a fire is detected. a fire detection section having a switching means (such as SCR) that causes an alarm current to flow through the fire detection section; a current detection circuit that detects the alarm current from the fire detection section; In a fire alarm device equipped with a transmission circuit that sends an address signal to a receiver and displays a sensor address, the receiver is configured to detect a non-alarming sensor when the number of alarming sensors reaches a predetermined value. A control means is provided for specifying the address of and sending out a current limit signal, and on the other hand,
Each of the sensors includes a current limiting circuit that limits the alarm current when a fire is detected to a constant value that allows the switching means to maintain continuity, and the transmission circuit identifies and receives a current limiting control signal from the receiver. A current limit switching circuit is provided which sometimes switches the limit value of the current limit circuit to a lower value.

[Function] In the fire alarm device of the present invention having such a configuration, alarms from a predetermined number of sensors connected to the same line from the receiver, for example, alarms from two sensors, can be activated. When detected, a current limit control signal will be sent by specifying the address of another sensor, and at this time, if the sensor that is in the non-alarm state identifies and receives the current limit control signal from the receiver, it will send out a current limit control signal. , the limiting value of the current limiting circuit is switched to, for example, a predetermined value below the steady monitoring current.

For this reason, even if a fire is detected by a sensor whose current limit value has been switched to a lower value, the line current between it and the receiver will hardly increase, and the line current will increase depending on the number of alarms from the sensor up to that point. Since the line current is maintained, the sensor supply voltage due to the line resistance does not drop any further, and information transmission between the receiver and the sensor can be guaranteed.

On the other hand, even if a fire is detected by a sensor whose current limit value has been switched to a lower value and the SCR provided in the fire detection section is triggered, the SCR cannot be maintained in a conductive state due to the current limit. However, while the fire detection output is being obtained, the S
Since the CR is conductive, the current detection circuit can provide the transmission circuit with the minimum current detection output necessary for signal transmission to the receiver, and due to the current limit, it is no longer possible to maintain continuity in the SCR and light up the alarm indicator light. However, fire detection information and address information can be transmitted normally from the detector to the receiver.

Furthermore, due to the current limit, the alarm indicator light cannot be lit when a fire is detected, but since the alarm indicator light of the sensor that triggered the alarm before the current limit value was changed is already lit, any further alarm indicator lights will be lit. Even if you don't, no particular problem will occur.

[Example code] FIG. 1 is a block diagram showing one embodiment of the present invention.

In FIG. 1, 1 is a receiver, and a plurality of addressable sensors 3A, 3B, .
・, 3N are connected.

The receiver 1 is provided with a receiving circuit 9, which receives and decodes a transmission signal containing fire detection information and unique address information transmitted when a fire is detected by any of the addressable sensors 3A to 3N, and outputs the received signal to the control circuit 10. occurs, and control circuit 1
0, the fire detection information and unique address information are decoded and the alarm display unit 11 is made to display a fire alarm and a fire alarm display, as well as display the decoded sensor address. Furthermore, when the control circuit 10 determines that the number of alarm sensors has reached a predetermined number, the transmission circuit 12 specifies the unique address of an addressable sensor other than the alarm sensor and sends a current limit control signal. Has controllability.

The control function of the control circuit 10 that sends out this current limit control signal is such that, for example, when it detects the alarms of two addressable sensors, it specifies the unique address of the other addressable sensor that is not alarming and limits the current. It begins to send control signals.

Figure 2 shows the addressable sensors 3A to 3 shown in Figure 1.
This is a circuit block diagram showing one embodiment of N. In this embodiment, a plurality of sensors installed in the same warning area are grouped, and only a specific sensor among them is given a unique address. An example is taken in which a parent sensor is used and a plurality of other sensors are cascade-connected to the parent sensor as child sensors.

In FIG. 2, 3 is a parent sensor with a function as an addressable sensor, and terminals 13a of the parent sensor 3,
13b, power supply signal lines 2a and 2b from receiver 1
is connected to the terminals 14a and 14b of the parent sensor 3, and between the power supply and signal lines 15a and 15b separately drawn out, there are a plurality of child sensors 16A to 16N using normal sensors that do not have unique addresses. are connected in parallel, and a terminating resistor 1 is installed at the end of the power signal lines 15a and 15b for detecting disconnection.
7 is connected.

The parent sensor 3 as an addressable sensor includes a current detection circuit 5 that detects the alarm current caused by the fire detection of the fire detection unit 4, and an address setting circuit 7 that sets the current detection circuit 5 when the detection output of the current detection circuit 5 is obtained. A transmission circuit 6 for transmitting unique address information to a receiver together with fire detection information, and an alarm indicator light 8 which is driven to be lit by the alarm current of the fire detector 4 are provided. Note that a resistor R7 is connected in parallel to the alarm indicator light 8 for protection and prevention of lighting during normal monitoring.

In addition to this, in the present invention, a current limiting circuit 18 is newly provided, and the current limiting circuit 18 can keep the alarm current at the time of fire detection conducted through the SCR of the fire detection section 4, and the alarm indicator light 8. It has a constant current function that limits the current to a constant value that allows lighting, for example, 6 mA.

Here, the alarm indicator light 8 of the parent sensor 3, the current limit circuit 18,
The current detection circuit 5, the transmission circuit 6, and the address setting circuit 7 are built into the sensor base, while the fire detection section 4 is provided in the sensor body, which is detachable from the sensor base. That is, the fire detection section 4 provided in the sensor body is mechanically and electrically connected removably to the fitting terminals 19a, 19b on the +) side and the fitting terminal 20 on the (-) side of the sensor base. When the sensor body including the fire detection section 4 is removed from the sensor base, the fitting terminals 19a and 19b are disconnected, and the power supply to the built-in circuit of the sensor base is cut off.

On the other hand, the power supply signal lines 15a and 15b connected to the child sensors 16A to 16N are connected to the connection terminals 14a and 14b, and the connection terminal 148 on the (+) side is connected to the line on the mating terminal 19b side. wire connection, and on the other hand, connection terminal 14
b is connected between the alarm indicator light 8 and the current limiting circuit 18. Therefore, for the current limiting circuit 18 of the parent sensor 3,
Fire detection section 4 of parent detector 3 and child detectors 16A to 16N
are connected in parallel, so that even if either the fire detection section 4 of the main sensor 3 or the child sensors 16A to 16N is activated by detecting a fire and sends an alarm current, the current is limited by the current limiting circuit 18. You will be killed.

The current limiting circuit 18 provided in the parent sensor 3 is a transistor T
A constant current circuit is configured by rl, Tr2, and resistors R1, R2, and R3. In this current limiting circuit 18, in the steady monitoring state, the transistor Tr2 is off and the transistor T
rl is turned on, and a steady monitoring current of, for example, 0.7 mA is flowing. On the other hand, when either the fire detection section 4 of the main sensor 3 or the child sensors 16A to 16N is activated due to fire detection and an alarm current flows, the transistors Tr1 and Tr2 are turned on and perform constant current operation. The current limit value at this time is I=VBE/R2, where VBE is the voltage between the emitters of transistors 'l' and rl.

The current detection circuit 5 provided subsequent to the current limiting circuit 18 includes a transistor Tr3 and resistors R4 and R5.

A voltage comparator with R6 and a current limiting circuit 1
The transistor Tr3 receives a voltage input according to the current value determined by the transistor Tr3, divides the voltage by the resistors R4 and R5, and inputs the divided voltage to the base of the transistor Tr3. Therefore, in the steady monitoring state, the impedance of the fire detection section 4 is sufficiently larger than the current limiting circuit 18, so the output voltage from the current limiting circuit 18 is low, so the transistors l'-r3 are turned off, and the fire is detected. When a constant current determined by the constant current operation of the current υ1 limiting circuit 18 flows due to the alarm current caused by do.

The collector output of the transistor Tr3 of the current detection circuit 5 is connected to the input terminal IN of the transmission circuit 6, and in the steady monitoring state where the transistor Tr3 is turned off, the input terminal IN is set to H level via the resistor R6. has been
When the transistor Tr3 is turned on due to fire detection, the input terminal IN is pulled to the L level, and the L level of this input terminal IN is pulled to the L level.
By drawing in the level, the transmission circuit 6 comes to transmit the fire detection information together with the unique address information set by the address setting circuit 7 to the receiver la1.

Further, the transmission circuit 6 receives the current limit control signal sent from the receiver 1 shown in FIG. 1, and performs current limit switching control to set the output terminal OUT to L level when the received signal matches its own unique address. The output terminal OUT of the transmission circuit 6, which generates a control output for The circuit 18 can normally perform current limiting operation. On the other hand, when the output terminal OUT of the transmission circuit 6 is set to L level by identification reception of the current limit control signal from the receiver, the transistors Trl and T of the current limit circuit 18
r2 is forcibly turned off, and the resistance R is further reduced compared to the resistance R1.
Since the resistance value of No. 3 is sufficiently large, the current limiting circuit 18 is thereby switched to a current limiting state in which a monitoring current lower than, for example, 0.7 mA, such as 0.5 mA, flows in the steady monitoring state.

FIG. 3 is a circuit block diagram showing an embodiment of the fire detection section 4 of the main sensor 3 shown in FIG. 2.

In addition, the child sensors '16A to 1 connected to the parent sensor 3 in a subordinate manner
6N also has the same configuration. In addition, the child sensor 16
A to 16N are provided with a fire detection unit 4 shown in FIG. 3 and an alarm indicator light 8, which is connected in parallel with a resistor R7, as represented by 16A.

In FIG. 3, the fire detection unit 4 is provided with a fire detection circuit 21, and in the case of a photoelectric smoke detection mechanism, for example, the light reception output is detected by detecting the scattered light of incoming smoke due to intermittent pulsed light emission. It is configured to generate a fire detection output when a predetermined level is reached. That is, the fire detection circuit 21 will intermittently generate a fire detection output when a fire is detected.

The output of the fire detection circuit 21 is 5 as a switching means.
It is applied to the gate of CR22, and 5CR22 is kept conductive upon receiving a trigger from the detection output of the fire detection circuit 21.
By maintaining conductivity of this 5CR22, an alarm current is caused to flow. At this time, the alarm current due to the continuity of 5CR22 is controlled by the current limiting circuit 18 as shown in FIG.
The current is limited to a constant current, for example, 6 mA, which can maintain conductivity of 22 and light the alarm indicator lamp 8.

Next, the operation of the above embodiment will be explained.

Now, suppose that among the plurality of addressable sensors 3A to 3N connected to the receiver 1 of FIG. 1, a fire is detected in the addressable sensor 3A at time t1, for example, as shown in the timing chart of FIG. 4. As shown in FIG. 2, since the addressable sensor 3A has a current limiting circuit 18, the alarm current of the fire detection section 4 is limited to 6 mA, and at the same time, the transmission circuit 6 of the addressable sensor 3A
A transmission signal containing fire detection information and unique address information is sent to the receiver 1. This transmission signal is transmitted to the receiver 1
The control circuit 10 determines the fire detection information and causes the alarm display section 11 to display a fire alarm, and also determines the address information and displays the sensor address.

Subsequently, if a fire is detected by the 7 dressable sensor 3B at time t2 in FIG. 4, the alarm current will be 6.
mA, and in reception@1, the transmission signal from the addressable sensor 3b is received and the sensor address is displayed on the alarm display section 11.

Here, the number of alarm sensors in the control circuit 10 of the receiver la1 is 2.
Since the receiver 1 is equipped with a function to send a current limit control signal to other non-alarm sensors, the addressable sensors 30 to 3N other than the addressable sensors 3A and 3B that have already issued an alarm from the receiver 1. A current limit control signal is sent by specifying a unique address.

In other non-alarm addressable sensors that receive the current limit control signal from the receiver 1, the current limit control signal from the receiver 1 is sent to the transmission circuit 6 as shown in FIG. When the identification is received, an L level output is generated at the output terminal OUT, and the transistors Trl and Tr of the current limiting circuit 18
2 is forcibly turned off, and as a result, in the case of a non-alarming addressable sensor, the steady monitoring current of 0.7 mA is lower than that of 0.5 mA, as shown in sensor 3N in Fig. 4, for example. limited to. Therefore, even if the third and subsequent sensor alarms are triggered, the line current of the power supply signal lines 2a and 2b from the receiver 1 is maintained at the alarm current of two alarm sensors, and Since there is no increase in line current as described above, an increase in voltage drop due to line resistance is suppressed, and information transmission between the alarm sensor and the non-alarm sensor can be guaranteed.

Next, when a fire is detected by a non-alarming sensor whose current limit value has been switched to a lower value by a current limit control signal from the receiver 1, the operation is as follows.

Assume that at time t2 in FIG. 4, for example, the current limit value is switched to a lower value in the non-alarming addressable sensor 3N, and a fire is detected at subsequent time tn.

At this time, the fire detection section 4 is intermittently producing a fire detection output as shown in Fig. 3, and although 5CR22 cannot maintain continuity due to current limitation, while the fire detection output is being obtained, It will be conductive. As a result, while 5CR22 is conductive due to the fire detection output, the transistor l'-r3 of the current detection circuit 5 shown in FIG. 2 is turned on, and the input IN of the transmission circuit 6 can be set to L level.

Here, the L level of the input terminal IN required for the transmission operation of the transmission circuit 6
If the level pull-in time is ΔT2, then ΔT2=20ms to prevent noise and chattering of mechanical contacts.
degree is necessary.

Therefore, the signal input period ΔT required for the transmission operation of the transmission circuit 6
By setting the generation time ΔT1 of the fire detection output to be longer than 2=20ms, for example, ΔT1=4QmS, the fire detection information and address information can be sent normally to the receiver 1 even if the continuity of 5CR22 cannot be maintained due to the current limit. can be transmitted.

Furthermore, when a fire is detected by the sensor which has been switched to a current limiting state with a lower current value by the current limiting control signal from the receiver 1, the alarm indicator lamp 8 cannot be turned on due to the current limiting; Alarm indicator lights are used when a fire is received and people go to the scene and check which detectors have activated.
For this reason, it is necessary to turn on the alarm indicator light 8 up to the second alarm, but there is no particular problem even if the alarm indicator light is turned on for the third alarm and beyond, since there is no need for on-site confirmation.

In the above embodiment, when the receiver 11 detects alarms from two sensors, a current limit control signal is sent to the sensor that is not alarming, but the current limit control signal is The number of sensor alarms to send out can be determined as appropriate.

Furthermore, in the above embodiment, as shown in FIG. 2, an addressable sensor is taken as an example in which a plurality of child sensors 16A to 16N are connected to a parent sensor 3 in a subordinate manner. Of course, it is also possible to use a single addressable sensor without a child sensor.

[Effects of the Invention] As explained above, according to the present invention, when the receiver determines that the number of alarming sensors has reached a predetermined number, the address of another non-alarming sensor is specified. A current limit signal is sent, and the sensor that recognizes and receives this current limit control signal sets the fire alarm current to a constant current, for example, a current value that can maintain continuity of a switching means such as an SCR installed in a fire detection section. Since the current limiting circuit that limits the current to By suppressing the drop in the sensor supply voltage to a predetermined value, it is possible to guarantee the information transmission function between multiple sensors connected to the same line and the receiver, making it possible to connect multiple addressable sensors to the receiver. The reliability of the fire alarm system can be further improved.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing an embodiment of the present invention; Fig. 2 is a circuit block diagram showing an embodiment of the addressable sensor of Fig. 1; Fig. 3 is a circuit block diagram showing an embodiment of the addressable sensor of Fig. 1; A circuit block diagram showing an embodiment of the fire detection section shown in FIG. 2; FIG. 4 is a timing chart showing the operation of the present invention. 1: Receiver 2a, 2b: Power supply signal line 3A to 3N Near address supplement sensor 3: Main detector 4: Fire detection section 5: Current detection circuit 6: Transmission circuit 7: Address setting circuit 8: Alarm indicator light 9: Receiving circuit 10: Control circuit 11: Alarm display section 12: Transmitting circuit 13a, 13b, 14a, 14b: Terminals 15a, 15b
: Power supply signal line (for child sensor) 16A to 16N = Child sensor 17: Termination resistor 18: Current limiting circuit 19a, 19b, 20: Fitting terminal 21: Fire detection circuit 22: 5CR (switching means) Tr1 to Tr3 :Transistor R1 to R6: Resistor

Claims (1)

[Claims] A plurality of sensors each having a unique address are connected between a power supply and signal line drawn out from a receiver, and each of the sensors is maintained conductive and sends an alarm current when a fire is detected. A fire detection section having a switching means, a current detection circuit that detects an alarm current from the fire detection section, and when a detection output of the current detection circuit is obtained, a unique address signal is sent to a receiver for detection. In a fire alarm system equipped with a transmission circuit for displaying a device address, when the number of alarm sensors reaches a predetermined number, the receiver specifies the address of a non-alarm sensor and sends a current limit control signal to the receiver. A current limiting circuit is provided in each of the sensors to limit the alarm current at the time of fire detection to a constant current that can maintain continuity of the switching device, and a current limiting circuit is provided in each of the sensors to transmit a current from the receiver to the switching device. A fire alarm device comprising: current limit switching means for switching the limit value of the current limit circuit to a lower value when a current limit control signal is identified and received.