JPH0935155A - Information transfer circuit for fire monitor and control board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely protect a circuit by a low fuse operation current such as several tens mA. SOLUTION: An information transfer circuit for a fire monitor and control board which outputs an information transfer signal from an information transfer terminal to an external unit 14 as necessary to drive the unit 14 at the time of receiving a fire detection signal from a fire sensor and judging the occurance of a fire is provided with an electronic fuse circuit 17 for turning an output line to an OFF state when a current flowing from the terminal F1 into the output signal line exceeds a prescribed value. A fuse monitoring part 15 monitors the output voltage of the circuit 17, and at the time of detecting the OFF of the output voltage, turns on a fuse OFF display lamp 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer circuit of a fire monitoring and control panel which operates by sending a transfer signal to an external unit when a fire is judged, and particularly, the transfer circuit exceeds an allowable limit. The present invention relates to a transfer circuit of a fire monitoring and control panel having a function of a fuse that disconnects a circuit in a cut state when a current flows.

[0002]

2. Description of the Related Art Conventionally, in a fire monitoring and control panel, when a fire detection signal is received from a fire detector and it is judged that a fire has occurred, the fire monitoring and control panel itself displays a fire alarm, and at the same time, The transfer circuit sends a transfer signal to a display unit installed at another location to enable fire indication.

In such a transfer circuit, a fuse is provided in order to protect the circuit from a short circuit in the signal line connecting the external unit or the external unit.

[0004]

However, in recent years, the transfer signal current has been reduced, and the transfer current required to drive the external unit is, for example, 30 mA to 50 mA.
Is suppressed to a low current. Therefore, for circuit protection, a fuse corresponding to the transfer current of 30 mA to 50 mA may be used, but in reality, there is no fuse that can be cut by a current of several tens of mA, and even the thinnest fuse has an operating current of For example, 200 mA is required.

Therefore, in order to protect the transfer circuit whose operating current is as low as several tens of mA, it is unavoidable to use a fuse that is far from the actually required fuse operating current of 200 mA. There was a risk that protection could not be ensured. An object of the present invention is to provide a transfer circuit of a fire monitoring control board, which can surely protect the circuit with a fuse operating current of several tens mA.

[0006]

In order to achieve this object, the present invention, when receiving a fire detection signal from a fire detector to judge a fire, transfers a signal from a transfer terminal to an external unit as needed. Regarding the transfer circuit of the fire monitoring control panel that operates by outputting a report signal, an electronic fuse that is provided on the transfer line of the transfer signal to the transfer terminal and disconnects the output line to the disconnected state when the current exceeds the specified value A circuit and a fuse monitoring circuit section for monitoring the output voltage of the electronic fuse circuit, detecting that the output voltage has been cut off, and displaying a blown fuse are provided.

The electronic fuse circuit is biased by, for example, a first transistor inserted and connected to the output line, a current detection resistor connected in series with the first transistor, and a voltage across the current detection resistor, and feedback-controls the first transistor. A second transistor and a control resistor for reverse biasing the first transistor by a control current of the second transistor,
The circuit configuration is such that the first transistor is cut off by the operating current of the second transistor when the current flowing through the output line exceeds a predetermined value.

By providing such an electronic fuse circuit in the transfer circuit, the operating current for circuit protection can be set to an arbitrary fuse operating current of 200 mA or less, which is the limit of the conventional fuse, and it can be ensured. It is possible to protect the circuit by detecting excessive current. Therefore, as the current of the transfer circuit becomes lower, the capacity of the power supply circuit corresponding to this can be made smaller and the cost can be reduced. In other words, conventional fuses can only blow at a minimum of 200mA,
A circuit element having a large current capacity capable of withstanding a short circuit current of 200 mA is required. However, in the present invention, since the fuse operating current of several tens of mA which is actually required can be surely cut, a circuit element having a low current capacity can be used, and the circuit can be downsized and the cost can be reduced. Can be further improved.

[0009]

1 is a block diagram of a fire alarm system using a fire monitoring and control panel having a transfer circuit according to the present invention. In FIG. 1, a plurality of sensor lines 2-1 to 2-n are drawn out from the fire monitoring control board 1, a plurality of fire detectors 3 are connected to each line, and a disconnection detection is further provided at the end of the line. The terminating resistor 4 of is connected. Sensor line 2-1
Corresponding to ~ 2-n, the fire monitoring control board 1 has a receiving circuit 5
-1 to 5-n are provided. Receiver circuits 5-1 to 5-n
Receives a fire detection signal from any one of the fire detectors 3 and outputs a fire reception signal to the MPU 6 as the control means.

When the MPU 6 receives a fire reception signal from any of the receiving circuits 5-1 to 5-n and judges a fire, it displays a fire alarm. The MPU 6 is provided with an operation unit 7, a display unit 8, a main sound device 9, a district sound control circuit 10 and a transfer circuit 13. A bell control line 11 is drawn from the district sound control circuit 10 to connect a plurality of district bells 12 as a district sound device. As the main acoustic device 9,
A buzzer, a speaker, etc. are provided.

An external display unit 14 is connected to the transfer circuit 13. The transfer circuit 13 outputs a transfer signal to the external display unit 14 in response to the transfer output instruction when the MPU 6 judges a fire, and in addition to the alarm display on the fire monitoring control panel 1, it is installed outside. Even the external display unit 14 that is present can display a fire alarm.

In the transfer circuit 13 of the present invention, an electronic fuse circuit for performing a circuit breaking operation at a predetermined operating current on the output line of the transfer signal to the transfer terminal connected to the external display unit 14. Is provided. This transfer circuit 13
Corresponding to the electronic fuse circuit provided in, the MPU 6 is provided with a fuse monitoring unit 15 realized by a program function, and the display unit 8 displays the disconnection state of the transfer signal output line due to the operation of the electronic fuse circuit. A fuse blown indicator lamp 16 is provided.

Further, the fire monitoring and control panel 1 is provided with a power source section 20. The power supply unit 20 is supplied with commercial AC 100V and is required to output the transfer signal in the transfer circuit 13 by the DC.
30V, D for the circuit units such as the receiving circuits 5-1 to 5-n
C24V, DC10 for driving the display of the display unit 8
The power supply voltage of 5V DC for operating the MPU 6 is output.

FIG. 2 is a circuit diagram showing a specific example of the embodiment of the transfer circuit of the present invention. In FIG. 2, the transfer circuit 13
Are transfer terminals F1, F2, F to the external display unit 14.
3 and connects the signal lines 21a, 21b, 21c. A transfer signal output line is connected to the transfer terminal F1 from the power supply line of the power supply voltage + 30V via the electronic fuse circuit 17 and the diode D1.

The common side of the switching relay contact 19a is connected to the transfer terminal F2. Switching relay contact 19a
The A side is open and the B side is connected to the transfer terminal F3 and is also grounded. Switching relay contact 19a
Is a relay contact of the relay 19 connected to the collector of the transistor Q4 which is turned on when the MPU 6 judges a fire.

That is, when the MPU 6 judges a fire, the transistor Q4 is turned on via the resistor R6 and the relay 19 is operated to switch the switching relay contact 19a from the A side to the B side. By switching the switching relay contact 19a to the B side, the transfer terminal F1 and the external display unit 1
4, a transfer terminal F2, a switching relay contact 19a, and a circuit leading to the ground connection are configured, and the transfer current flowing by the circuit formation can cause the external display unit 14 to perform a fire display operation and a buzzer sound.

Power is supplied to the external display unit 14 at F1 and F3, and the power lamp of the external display unit 14 is turned on. The electronic fuse circuit 17 includes a first transistor Q1, a second transistor Q2, a current detection resistor R1, and a control resistor R2. That is, the transistor Q1 and the current detection resistor R1 are connected in series to the output line to the transfer terminal F1, and the base and emitter of the second transistor Q2 are biased by the voltage across the current detection resistor R1.
The transistors Q1 and Q2 are feedback-connected to each other.

That is, the bias voltage of the current detection resistor R1 due to the collector current of the transistor Q1 is applied to the transistor Q.
It supplies the base current to 2 and transistor Q at the same time.
It has a connection configuration in which the base current of the transistor Q1 is supplied by the collector current of 2 and the positive feedback is provided to each other. Such a circuit composed of the transistors Q1 and Q2 and the resistors R1 and R2 has a reverse circuit due to the voltage across the resistor R2 of the transistor Q1 caused by the collector current of the transistor Q2 when the current flowing through the current detection resistor R1 reaches a predetermined value. It constitutes a current limiting circuit that cuts off by bias.

That is, when the current value is less than a predetermined value, the resistance R
Since the voltage across 1 is lower than the specified value and the collector current of the transistor Q2 is small, the voltage across the resistor R2 is also small, and the reverse bias voltage between the collector and base of the transistor Q1 due to the voltage across the resistor R2 is sufficiently low. The transistor Q1 is on. Current detection resistor R
When the current flowing through 1 exceeds the specified value, transistor Q2
When the collector current of the transistor Q1 increases, the voltage across the resistor R2 increases and the transistor Q1 is reverse-biased.
1 is cut off, and the output line to the transfer terminal F1 is cut off.

In the cutoff state of the transistor Q1, a current for maintaining the cutoff state flows in the circuit passing through the resistor R2 and the transistor Q2.
The current detection resistor R1 is, for example, 100Ω, but the control resistor R1
2 is 47 kΩ, which is sufficiently high, and the current flowing through the transistor Q2 for keeping the transistor Q1 in the cutoff state is a very weak current, and the output line can be regarded as a substantially disconnected state.

A voltage detection circuit 18 is provided for the electronic fuse circuit 17. The voltage detection circuit 18 is composed of a transistor Q3, resistors R3, R4, R5 and R7 and a Zener diode ZD1. The output of the electronic fuse circuit 17 is divided by the resistors R3 and R4. A Zener diode ZD1 for absorbing noise is connected in parallel with the resistor R4.

The output of the electronic fuse circuit 17 divided by the resistors R3 and R4 is transferred to the transistor Q3 via the resistor R5.
Supplied to the base. The + 5V power supply is supplied to the collector of the transistor Q3 via the resistor R7. The voltage between the collector and emitter of the transistor Q3 is set to MPU6.
Is taken into the port P2 and the operation of the electronic fuse circuit 17 is monitored. When the current flowing through the electronic fuse circuit 17 is less than the predetermined current value, the + 30V power source is supplied to the voltage detection circuit 18 via the electronic fuse circuit 17,
The transistor Q3 is on. Then, the + 5V power source is electrically connected to the ground via the resistor R7, and the port P2 of the MPU 6 is connected.
Becomes L level.

When a current of a predetermined value or more flows in the electronic fuse circuit 17, when the electronic fuse circuit 17 is activated and the output line to the transfer terminal F1 is disconnected, the base current of the transistor Q3 decreases to turn off. And + 5V
The + 5V power supply is supplied to the port P2 of the MPU 6 which is pulled up to the power supply via the resistor R7. That is, MPU
The port P2 of 6 has a power supply voltage of +5 V at the L level because the transistor Q3 is on when the electronic fuse circuit 17 is not operating, and the +5 V power supply resists when the transistor Q3 is turned off by the operation of the electronic fuse circuit 17.
It is supplied to the H level.

The fuse monitoring section 15 provided in the MPU 6 is
The state of the port P2 to which the output of the voltage detection circuit 18 is connected is monitored. When the port P2 changes from the L level to the H level, the port P3 is pulled from the H level to the L level, and the LED connected to the + 10V power supply line. The fuse blown indicator lamp 16 using is turned on. Next, the operation of the embodiment of FIG. 2 when a short circuit occurs on the external display unit 14 side will be described. First, in the steady monitoring state, MP
Transistor Q4 because U6 does not judge fire
Is off, the relay 19 is in an inoperative state, the switching relay contact 19a is closed to the A side in the drawing, and the transfer signal is not output to the external display unit 14.

In this state, if a short circuit occurs in the external display unit 14 or between its signal lines 21a and 21c, the external display unit 14 is connected from the + 30V power supply line through the electronic fuse circuit 17 and the diode D1.
Short circuit current flows to the side. In response to this short circuit current, the electronic fuse circuit 17 causes the transistor Q2 to operate when the short circuit current exceeds the specified fuse operating current.
1 is cut off, and the output line to the transfer terminal F1 is cut off in a substantially cut state.

At this time, the transistor Q3 of the voltage detection circuit 18 is turned off, and the port P2 of the MPU 6 is changed from L level to H level.
By setting the level, the fuse monitoring unit 15 detects the disconnection operation of the electronic fuse circuit 17, and the fuse disconnection indicator lamp 16
Lights up. At the same time, the MPU 6 may use a main sound device 9 or a dedicated buzzer to notify the blown fuse by an acoustic alarm such as intermittent ringing.

Next, the operation when a short circuit current flows due to a failure of the external display unit 14 when the MPU 6 judges a fire and outputs a transfer signal will be described. When the MPU 6 judges a fire, the transistor Q4 is turned on to activate the relay 19 to switch the switching relay contact 19a to the B side. As a result, a transfer current flows from the transfer terminals F1 to F2 through the control load in the external display unit 14, and the display operation of the external display unit 14 is performed.

However, if a short circuit current flows between the transfer terminals F1 and F2 due to a failure of the external display unit 14,
The electronic fuse circuit 17 operates to cut off the transistor Q1 by the transistor Q2 and disconnect the output line to the transfer terminal F1 in a disconnected state. At the same time, when the transistor Q3 of the voltage detection circuit 18 is turned off, the fuse monitoring unit 15 detects the change of the port P2 from the L level to the H level, and the fuse blown indicator lamp 16 is turned on to notify the operation of the electronic fuse circuit 17.

In the above embodiment, the external display unit 14 is taken as an example of the external transfer unit, but an appropriate transfer unit can be used in addition to this. Moreover, the operating current of the electronic fuse circuit 17 can be appropriately determined as necessary.

[0030]

As described above, according to the present invention, the circuit protection cutting operation can be performed for any fuse operating current below 200 mA, which is the limit of the conventional fuse. For this reason, it is possible to reliably cut the fuse operating current of several tens of mA required for the transfer circuit of which the current has been reduced, so that the fuse operating current is used as a circuit element used in the transfer circuit and the power supply circuit. A corresponding one having a small current capacity can be used, which can reduce the size and cost of the circuit.

[Brief description of drawings]

FIG. 1 is a block diagram of a fire monitoring system using a fire alarm control panel having a transfer circuit according to the present invention.

FIG. 2 is a circuit block diagram showing an embodiment of a transfer circuit according to the present invention.

[Explanation of symbols]

 1: Fire monitoring and control panel 2-1 to 2-n: Detector line 3: Fire detector 4: Termination resistance 5-1 to 5-n: Receiving circuit 6: MPU 7: Operation unit 8: Display unit 9: Main Sound section 10: District sound control circuit 11: Bell control line 12: District bell 13: Transfer circuit 14: External display unit 15: Fuse monitoring section 16: Fuse blown indicator light 17 :: Electronic fuse circuit 18: Voltage detection circuit 19 : Relay 19a: Relay contact for transfer 20: Power supply

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masashi Arikawa 2-1043 Kamiosaki, Shinagawa-ku, Tokyo Hochiki Co., Ltd.

Claims (2)

[Claims] 1. When a fire detection signal is received from a fire detector and a fire is judged, a fire monitoring control panel is operated by outputting a move signal from an alarm terminal to an external unit, if necessary. An electronic fuse circuit which is provided in an output line of a transfer signal to the transfer terminal and disconnects the output line in a disconnection state when a current flowing through the output line exceeds a predetermined value; A transfer circuit for a fire monitoring and control panel, comprising: a fuse monitoring circuit section that monitors the output voltage of the fuse circuit and detects when the output voltage is cut off, and displays a fuse cut. 2. The transfer circuit for a fire monitoring and control panel according to claim 1, wherein the electronic fuse circuit is connected in series with a first transistor inserted into the output line and connected to the first transistor. A current detecting resistor; a second transistor biased by a voltage across the current detecting resistor to feedback control the first transistor; and a control resistor reverse biasing the first transistor with a control current of the second transistor, A transfer circuit for a fire monitoring and control panel, characterized in that the operating current of the second transistor cuts off the first transistor when the current flowing through the output line exceeds a predetermined value.