JPS62272391A - Malfunctioning prevention circuit for disconnection monitor - 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 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a malfunction prevention circuit for a disconnection monitoring device used in disaster prevention equipment such as fire alarm equipment and theft prevention equipment.

[Background Art] As a disconnection monitoring device for monitoring disconnections in fire alarm equipment, etc., it is conceivable to provide a termination capacitor at the ends of a pair of electrical circuits.

This disconnection monitoring device monitors disconnection based on the charging voltage of the termination capacitor. Therefore, when the power is turned on, the charging voltage of the termination capacitor is unstable, which may cause the disconnection monitoring device to malfunction.

In addition, when a fire detector, etc. is activated, the fire detector, etc. becomes short-circuited, so the termination capacitor is discharged, and the voltage across the termination capacitor decreases. In this case, the disconnection monitoring device also detects malfunction. It can happen.

Further, even when restoring an activated fire detector or the like, the disconnection monitoring device may malfunction until the termination capacitor is completely charged.

[Object of the Invention] The present invention has been made by focusing on the problems of the above-mentioned background art, and is intended to reliably prevent malfunctions when power is turned on, when a fire detector, etc. is activated, and when a fire detector, etc. is restored. The object of the present invention is to provide a malfunction prevention circuit for a disconnection monitoring device for disaster prevention equipment.

[Embodiments of the invention] FIG. 1 is a circuit diagram showing one embodiment of the present invention.

The embodiment shown in FIG. 1 is an embodiment of fire alarm equipment, and includes a repeater connected to a receiver (not shown), and a terminating capacitor C.
It is composed of a terminator T including E, an electric line connecting the above-mentioned repeater and the terminator T, and a plurality of fire detectors DE provided in the electric line.

First, in the terminator T, a resistor R1 with a relatively large resistance value and a termination capacitor CE are connected in series, and a series circuit of a resistor R2 with a relatively small resistance value and a diode D1 is connected in parallel with the resistor R1. ing. In other words, the time constant is set such that the charging time to the termination capacitor CE is relatively long and the discharging time is relatively short.

Further, a Zener diode connected in parallel to the series circuit of the resistor R1 and the termination capacitor CE is used to prevent destruction of the capacitor GE when the termination T is connected with reverse polarity. The Zener diode also serves as voltage protection against external noise.

Inside the repeater, there is a power supply (for example, 2
A constant voltage circuit lO that sets the output voltage (4) to a predetermined constant voltage (for example, 10 V), an integrating circuit 11 that integrates this output voltage,
Inverter 1 that inverts the output signal from the integrating circuit 11
2, a metastable multivibrator 13 that receives the output signal of the inverter 1z as a reset signal, and a delay circuit 14 that delays the output signal of the monostable multivibrator 13 for a predetermined period of time.

? The output signal of the punch stabilizing multivibrator 13 is called a "clear pulse" in the sense that it clears the breakage detection latch L1, which will be described later. It is called a "discontinuation pulse."

Also, a positive power supply (for example, 24v) and common terminal C are connected, and between the L terminal and ground.

A series circuit of a resistor R3, a transistor TRI, and a resistor R4 is connected. By turning on the transistor TRI, the transistor TRI supplies power to the fire detector DE and charges the termination capacitor CE, and by turning it off, the power supply to the electric circuit is cut off and the fire detector DE is restored. It is something that makes you Also, the transistor TRI
When a fire detector is activated, its base voltage increases and that base voltage is used for fire detection.

Furthermore, a resistor R5, a transistor TR3, a resistor R6, and a diode ZD are connected between the positive power supply and the ground.
A series circuit with transistor TR3 and resistor R6 is connected, and a connection point between transistor TR3 and resistor R6 is connected to the L terminal. The Zener voltage of the Zener diode ZD2 is, for example, 9V. By turning on the transistor TR3, a discharge loop of the termination capacitor GE is formed, and at this time, a disconnection detection signal is generated at the 7th node (point Pl) of the Zener diode ZD2.

Also, resistors R7 and R8 are connected between the positive power supply and ground.
and a transistor TR4 are connected, and a connection point between resistors R7 and R8 is connected to the base of the transistor TR3.

Further, a Zener diode ZD1 is connected to the base of the transistor TRI. This Zener diode ZD1 constitutes a constant current circuit together with the transistor TRI, and defines the upper limit of the load current (the current flowing through the electric circuit, that is, the fire detector DE) of the transistor TRI.
are doing.

Further, between the output terminal of the constant voltage circuit 10 and the ground, a series circuit of resistors R9, RIO1RIL, and RL2 connected to a voltage higher than the reference voltage is connected, and each connection point is connected to P2 in descending order of voltage. ．． Let them be P3 and P4.

The disconnection detection comparator 20 that performs disconnection detection compares the disconnection detection signal (voltage of PL) with a reference voltage (voltage of P2, for example 6V), and when the disconnection detection signal is higher than the voltage of point P2. In this case, it is determined that the electric line connected between the C and L terminals is disconnected.

On the other hand, a comparator 21 for inhibiting disconnection detection at the time of a fire alarm sets the base voltage of the transistor TRI to a reference voltage (the voltage at point P3, for example 4
V), when the base voltage of the transistor TRI becomes equal to or higher than the reference voltage at point P3 due to the occurrence of a fire,
This prohibits the disconnection detection operation.

The comparator 22, which prohibits the disconnection detection operation at the time of recovery, connects the output voltage of the disconnection detection comparator 20 to the resistors R13 and R.
14 is compared with a reference voltage (voltage at point P4, for example, 2V), and the disconnection detection comparator 20
When the voltage divided by the output ``voltage'' becomes equal to or higher than the reference voltage at point P4, it is determined that it is time to recover, and the disconnection detection operation is prohibited.The resistance value of resistor RL4 is relatively small. A capacitor CI is connected in parallel with the large resistor R14.The resistor R14 increases the discharge time constant of the capacitor C1.

Further, the fire comparator 30 that detects a fire compares the base voltage of the transistor TRI with a reference voltage (the voltage at point P3, for example, 4V), and compares the base voltage of the transistor TRI
When the base voltage of I becomes equal to or higher than the reference voltage of point P3, it is determined that there is a fire.

The disconnection detector 7ch L1 that holds the output signal of the disconnection detection comparator 20 outputs rL when the electrical circuit is not disconnected, that is, when it is normal.
", and outputs rHJ when the line is disconnected. ANDL is to set the disconnection detection latch L1 when the lfV line is present and a disconnection detection pulse is generated. A
ND2 is for resetting the disconnection detection latch L1 when a clear pulse is generated in a steady state. AND3 outputs an "H" signal when a break detection pulse is generated in a steady state.

N0RI prohibits a disconnection alarm when the fire detector is restored, and normally outputs rHJ. N
0R2 occurs when a recovery pulse is received from a receiver (not shown) or when AND3 outputs an H signal due to a disconnection pulse.

The transistor TRI is turned off to ensure the recovery operation and disconnection detection operation of the activated fire detector. In addition to this, OR1 and OR2 are provided.

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

First, when the positive power is turned on, the constant voltage circuit lO
starts, and its output voltage gradually increases. During this time, the output voltage of the integrating circuit 11 also increases gradually, and the inverter 12 becomes "H" until the output voltage of the integrating circuit 11 reaches a predetermined value.
During this period, the monostable multivibrator 13 is held in a reset state, so it does not generate a clear pulse, and the delay circuit 14 does not generate a break detection pulse.

As a result, AND3 is not opened and no recovery pulse is input, N0R2 outputs rl(J, transistor TRI is turned on, terminating capacitor CE starts charging, and is sufficiently charged.

Furthermore, while the inverter 12 is generating rHJ output,
The connection/disconnection latch L1 and the fire latch L2 are also reset.

On the other hand, when the output voltage of the constant voltage circuit IO reaches the constant voltage, the inverter 12 sets its output voltage to "L", so the monostable multivibrator 13
and the reset for the fire latch L2 is released.

Here, when the disconnection monitoring signal is input, the monostable multivibrator 13 generates a clear pulse. The disconnection monitoring signal is output by a receiving circuit (not shown) of the repeater when, for example, an address received from a receiver (not shown) matches an address of the repeater itself.

When the monostable multivibrator 13 generates a clear pulse, normally, the rLJ output of the interrupter inhibiting function generators 21 and 22 causes N0R1 to output rl (since it outputs J, so AND2) to prevent an interrupt detection. Use-, ChiLl
is cleared.

Then, after a predetermined time delay from the generation of the clear pulse, the delay circuit 14 generates a disconnection pulse (see FIG. 2).

Further, since N0RI normally outputs "H", the disconnection detection pulse opens AND3, the disconnection detection pulse is applied to the base of the transistor TR4, the transistor TR4 is turned on, and the transistor TR3 is turned on.

On the other hand, at this time, the output of N0R2 becomes rLJ due to the disconnection pulse passed through AND3, and the output of N0R2 becomes rLJ, and the output of transistor T
RI turns off.

When the transistor TRI is turned off, the power supply to the electric path between the C and L terminals is cut off, and when the transistor TR3 is turned on, a discharge loop of the termination capacitor CE is formed by the resistors R2 and R5 and the transistor TR3.

As a result, the termination capacitor CE is discharged, so C,
A voltage of around 22V is generated between the L terminals, and therefore a voltage of approximately 2V or less, which is obtained by subtracting the voltage between the C1L terminals from the 24V power supply voltage, is generated at the point P1. here,
At point P2, where the output voltage 10■ of the constant voltage circuit is divided,
For example, since a voltage of 6V is generated and the voltage at point P1 is lower than that, the output of the connection/disconnection comparator 20 remains at "L". For this reason, the output of AND 1 also remains rlJ, and the disconnection latch Ll cannot be set, and a signal rLJ indicating non-disconnection is generated at its Q output terminal.

If the electrical circuit is disconnected, perform the following actions.

In other words, a disconnection pulse is generated, transistor TRI is turned off, transistor TR4 is turned on, and transistor TR
3 is turned on, the electrical circuit is disconnected, so the terminating capacitor CE is not discharged, and the voltage across the terminating capacitor CE is not applied between the C and L terminals. Therefore,
The voltage at point P1 rises to approximately 9V, which is the Zener voltage of Zener diode ZD2. For this reason, the output of the connection/disconnection comparator 20 becomes "H", and while AND3 is outputting the disconnection detection pulse, ANDl outputs r) (j and sets the connection/disconnection latch L1. As a result, its Q output becomes rHJ, indicating a disconnection. Note that even if the power supply voltage fluctuates, the Zener diode ZD2
This serves to ensure that the voltage at point PL is higher than the voltage at point P2 when the electrical path between the terminals is disconnected.

Next, the fire detection operation will be explained.

When a fire occurs, the fire detector CE becomes short-circuited, and the fire detector DE, resistor R3, and transistor TR
A large current flows through L and resistor R4. For this reason, the voltage drop across the resistor R4 increases, and the transistor TR
The emitter voltage of I increases. Along with this, its base potential increases. Its base potential is applied to the non-inverting input terminal of the fire comparator 30.

On the other hand, the inverting input terminal of the comparator 30 is at the point P3.
The voltage is about 4V, which is about 4V. therefore,
When the base potential of the transistor TRI rises above the voltage at point P3, the fire comparator 30 outputs "H" and the fire latch L2 is set. At this time, the rHJ signal is output to the inverted output terminal of the fire latch L2, and this signal becomes a fire signal.

Note that the increase in the base potential of the transistor TRI is caused by the Zener voltage (for example, 6 V) of the Zener diode ZD1.
It will stop when it reaches . After this, the transistor TRI and the Zener diode ZD1 operate as a constant current circuit,
The current flowing through the activated fire detector DE is limited to a predetermined value.

Next, a description will be given of an operation to prevent malfunctions in wire breakage detection.

The timing when disconnection detection should not be performed is as follows:
Possible situations include when the power is turned on, when a fire alarm is issued, and when the fire detector I)H is restored.

First, we will explain what happens when the power is turned on.

The disconnection detection comparator 20 compares the voltage at point P1 and the voltage at point P2, which is a reference voltage, and determines that there is a disconnection when the voltage at point P1 is high. By the way, when the power is turned on, since the output voltage of the constant voltage circuit 1O is not high enough, the voltage at point P2 is low, and there is a possibility that it may be mistakenly recognized as a disconnection even if it is not a disconnection.

When the power is turned on, the output voltage of the constant voltage circuit 10 gradually increases, but the output voltage is integrated by the integrator circuit 11, the output voltage of the integrator circuit 11 is inverted by the inverter 12, and this inverted signal is sent to the monostable multivibrator. 13. It serves as a reset signal for the disconnection detection latch LL and the fire latch L2. Therefore, the reset signal is output from the inverter 12 until the output voltage of the constant voltage circuit 10 becomes sufficiently high, and during this period, even if a disconnection monitoring signal is input from a receiving circuit (not shown), the monostable multivibrator 13 does not receive a clear pulse. Because of this, it does not occur.

Since no disconnection detection pulse is generated from the delay circuit 14 when the power is turned on, disconnection detection is not performed and erroneous operation of disconnection detection does not occur when the power is turned on.

In addition, the reset signal of the inverter 12 is connected to OR2 and ORI.
It is input to the reset terminals of the disconnection detection latch L1 and the fire latch L2 through the latches L1 and L2, and the outputs of the latches L1 and L2 are set to "L".

Next, prevention of malfunction of disconnection detection when a fire is reported will be explained.

When a fire is reported, the fire detector DE is short-circuited, so the voltage at one point P1 becomes higher than the voltage at point P2, the disconnection detection comparator 20 outputs rHJ, and the disconnection detection latch L1 outputs a disconnection signal. Become. If this continues, disconnection detection will malfunction when a fire is reported.

However, in the case of -H, when the C and L terminals are short-circuited, a large current flows through the resistor R4, the collector potential of the transistor TRI becomes high, and its base potential also becomes higher than the voltage at the point P3. When the alarm is issued, the comparator 21 outputs "H", N0RI becomes rLJ, and AND3 is held at rLJ output state 7g. Therefore, ANDl is closed, disconnection detection latch L1 is not set, and a disconnection signal is not erroneously output.

Next, the malfunction prevention 1F for detecting disconnection when the fire detector DE is restored will be explained.

At the time of recovery, a recovery command from a receiver (not shown) causes
When a restoration pulse is manually applied from the restoration circuit (not shown) of the repeater, N0R2 outputs "L".
Since RI is turned off and power is no longer supplied to fire detector DE, the self-holding circuit of fire detector DE is released.

Furthermore, the disconnection detection latch L1 and the fire latch L2 are also reset by the recovery pulse.

On the other hand, since the electric path between C and L terminals is not disconnected, point P
1, a voltage corresponding to the Zener voltage of the Zener diode ZD2 is generated, and the disconnection detection comparator 20 generates an rH'' output. Due to this rHJ output, the capacitor C1 is charged while the recovery pulse is input, and the voltage at point P5 becomes higher than the voltage at point P4, and the disconnection prohibition IF controller 22 generates an rHJ output at the time of recovery. Make rLJ the output of N0RI.

After the recovery operation is completed, the transistor TR
When 1 is turned on, charging of the termination capacitor CE is started. During this charging, the voltage at point P1 may not become lower than the voltage at point P2, and disconnection detection comparator 20 may output rHJ. If this continues, a disconnection signal will be erroneously generated.

However, in the above case, comparator 2 that prohibits failure during recovery
Since the voltage at the non-inverting input terminal 2 is higher than point P4 for a predetermined period of time, N0RI outputs "L", AND3 is closed, and AND1 is also closed, so the above-mentioned malfunction 1 is prevented.

Note that since the resistance value of the resistor R14 is relatively large, the electric charge charged in the capacitor C1 is gradually discharged over a predetermined period of time.
The output voltage of No. 2 outputs an "H" signal for the predetermined time (the time required for the termination capacitor CE to be almost charged and the voltage at point P1 to be equal to or lower than the voltage at point P2). When the predetermined period of time has elapsed, the disconnection check prohibition W comparator 22 at the time of recovery is set to r.
LJ output is generated, and N0RI outputs rHJ in the normal state, but when this normal state is reached, the termination capacitor CE is sufficiently charged.

FIGS. 2(1), (2), (3), and (4) are time charts showing each operation of the above embodiment.

The above embodiment includes a reset means, a disconnection detection pulse output prohibition means, and a disconnection signal output prohibition means.

The reset means is a disconnection detection latch L that outputs and holds a disconnection signal by outputting a disconnection detection signal from the disconnection detection comparator 20.
1 until the output voltage of the power supply circuit 10 becomes stable when the power is turned on. Specifically, it is composed of an integrating circuit 11 and an inverter 12 whose output is inverted when the output of the integrating circuit 11 reaches a predetermined value, but other circuits may be used. Furthermore, instead of the disconnection detection latch Ll, a disconnection C output circuit such as a switching circuit having a self-holding unit may be used.

The disconnection detection pulse output prohibiting means prohibits the output of the disconnection detection pulse that causes the disconnection detection circuit composed of the transistors TR1 and TR3 and the disconnection detection comparator 20 to perform the disconnection monitoring operation while the fire detector DE is operating. It is a means to do so. Specifically, it is composed of a transistor TRI and a comparator 21 that prohibits failure detection when an alarm is issued, but other circuits may be used.

The L-stage disconnection signal output prohibition means, when the sensor DE is restored,
This is means for prohibiting the disconnection detection latch LL, that is, the disconnection signal output circuit from being set.

Specifically, no! Ail separate circuit disconnection detection comparator 2
An integral circuit that integrates the output of 0 and is composed of a charging resistor R13, a capacitor C1, and a discharging resistor R14, and an output is generated when the charging voltage of this integrating circuit exceeds a predetermined value. The comparator 22 and the output of the comparator 22 prohibit the output of the comparator 20 from being manually applied to the set terminal of the disconnection signal output circuit L1, and the gate circuit consisting of N0RI, AND・3, ANDI and the manually applied recovery pulse. Disconnection signal output circuit Ll
ORI to be passed to the reset terminal of.

Although it is configured with a gate circuit consisting of OR2, other configurations may be adopted.

In addition, in the example L, disconnection monitoring device and its error 1, FJ
J f + prevention + 1 circuit, 1 - is provided in the middle gtz; t =, but it may also be provided in the receiver A1), and it can also be used for theft prevention equipment, etc. Furthermore, instead of the monostable multivibrator 13, a timer or the like that generates an output at predetermined time intervals can also be used.

[Effect of the invention] The malfunction prevention circuit of the disconnection monitoring device for disaster prevention equipment of the present invention has the following features:
This has the effect of reliably preventing erroneous operation of disconnection detection when the power is turned on, when a fire detector or the like is activated, and when the fire detector or the like is restored.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of the present invention. FIGS. 2(1), (2), (3), and (4) are time charts showing operations in the above embodiment. 10... Constant voltage circuit, 11... Integrating circuit, 13... Monostable multi-bi break,
・14...Delay circuit, 20...Danken comparator, 21...Damage check prohibition comparator when alarm is issued, 2
2...Comparator for disconnection during recovery, 30...Comparator for fire, CE...Terminal capacitor. Ll... Dankengawa latch, Ll... Fire latch. Patent Applicant: f-Gabi Disaster Prevention Industry Co., Ltd., Agent
Arata Yokubo - Fig. 2 (1) I" Ojohata (2) llT 笽吻 Fig. 2 (3) Report of Yauke

Claims (5)

[Claims] (1) A termination capacitor is provided at the end of a pair of electrical circuits to which an abnormality detector such as a fire detector is connected, and the terminal capacitor is discharged when a disconnection detection pulse occurs, and the discharge voltage determines whether or not the electrical circuit is disconnected. This is a disconnection monitoring device for disaster prevention equipment that detects disconnection, and the output voltage of the power supply circuit that supplies power to the disconnection determination circuit is stabilized when the power is turned on. a reset means for resetting until the abnormality detector operates; a break detection pulse output prohibiting means for prohibiting the output of a break detection pulse that causes the disconnection determination circuit to perform a disconnection monitoring operation; A malfunction prevention circuit for a disconnection monitoring device, comprising: disconnection signal output prohibiting means for prohibiting the disconnection signal output circuit from outputting a disconnection signal when a detector is restored. (2) In claim 1, the reset means is characterized by comprising an integrating circuit that integrates the output voltage of the power supply circuit, and an inverter that inverts the output voltage of the integrating circuit. Malfunction prevention circuit for disconnection monitoring equipment. (3) In claim 1, the disconnection detection pulse output inhibiting means includes a transistor connected in series with the fire detector, and outputs the disconnection signal when the base potential of the transistor is higher than a reference potential. What is claimed is: 1. A malfunction prevention circuit for a disconnection monitoring device, comprising: a comparator for inhibiting disconnection when an alarm is issued, which supplies a reset signal to a reset terminal of the circuit. (4) In claim 1, the wire breakage signal output inhibiting means includes an integrating circuit that integrates the output of the wire breakage determining circuit, and a restoration time detection circuit that generates an output when the output of the integrating circuit is equal to or higher than a predetermined value. Consisting of a prohibition comparator, a gate circuit that prohibits the output of the disconnection determination circuit from being input to the set terminal of the disconnection signal output circuit based on the output of the disconnection detection prohibition comparator upon recovery, and a gate circuit that allows the recovery pulse to pass. A malfunction prevention circuit for a disconnection monitoring device. (5) The malfunction prevention circuit for a disconnection monitoring device according to claim 1, wherein the power supply circuit is a constant voltage circuit.