JP3287966B2 - Transmission line monitoring equipment for fire alarm equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in various fire alarm systems, and detects a short circuit in a transmission line to separate a short circuit occurrence point, and detects a short circuit recovery in the transmission line to detect a short circuit recovery point. And a transmission line monitoring device for connecting the two.

[0002]

2. Description of the Related Art Conventionally, in a fire alarm system, a voltage between a pair of transmission lines is detected as disclosed in, for example, Japanese Patent Application Laid-Open No. 62-73400, in order to prevent a system down due to a short circuit in the transmission line. Then, a relay contact is used to determine whether or not the transmission line is short-circuited, and to disconnect the transmission line determined to be short-circuited. Also, in order to recover the short circuit, the power of the fire receiver was restarted.

[0003]

However, in a method of detecting a voltage between a pair of transmission lines to determine a short circuit,
When the line resistance is large, there is a problem that a short circuit cannot be detected. For example, in a fire alarm system having a transmission line wiring resistance of up to 30Ω, a transmission voltage of DC 30V, a maximum transmission current of a fire receiver of 1.2A, and a normal transmission current of 0.1A, a wiring resistance of 30Ω exists. When the transmission line is short-circuited via this wiring resistance, the short-circuit current is 30 V / 3
Since 0Ω = 1A, a current of 0.1A + 1A = 1.1A continues to flow, and there is no voltage drop in this fire alarm system, so there is a problem that a short circuit cannot be detected. In addition, when disconnecting the transmission line after detecting a short circuit, there is also a problem that the operation speed is slow if a mechanical switch such as a relay is used, so that the voltage drop due to the short circuit affects all transmission lines. Was. Further, when the short circuit is recovered, it is necessary to restart the power of the fire receiver.

Therefore, the present invention can detect a short-circuit in a transmission line even if the line resistance is large, and can not only quickly disconnect the transmission line when a short-circuit is detected, but also use the transmission line monitoring device itself to recover the short-circuit when the short-circuit is recovered. The purpose is to obtain a new transmission line monitoring device that can be reconnected.

[0005]

SUMMARY OF THE INVENTION A transmission line monitoring device for a fire alarm system according to the present invention comprises a pair of transmission lines, which are a power line and a signal line extending from a fire receiver, or at least a pair of transmission lines branched from these transmission lines. A transistor inserted into at least one of the transmission line pair or the branch transmission line pair on the input side of the transmission line monitoring device, and connected to a base of the transistor in order to monitor a short circuit and short circuit recovery of the branch transmission line. A constant current circuit that supplies a constant base current, and is connected between the emitter and the collector of the transistor, and when the voltage between the emitter and the collector exceeds a predetermined value, it detects that the transmission line on the output side is short-circuited and short-circuits. When a short-circuit detection circuit that generates a detection signal and is connected to the output-side transmission line, and a load resistance between the output-side transmission lines exceeds a predetermined resistance value, A short-circuit recovery detection circuit that detects that the output-side transmission line has recovered from the short-circuit and generates a short-circuit recovery detection signal; and is connected to the short-circuit detection circuit and the short-circuit recovery detection circuit, and is activated by the short-circuit detection signal. ,
Turning off the transistor through the constant current circuit,
A line disconnection control circuit that disconnects the output side transmission line and activates the transistor via the constant current circuit when activated by the short circuit recovery detection signal, thereby reconnecting the output side transmission line. It is provided. The transmission line monitoring apparatus according to the present invention further includes an address signal generation circuit that generates different address signals in place of the short-circuit notification signal.

[0006]

In the present invention, the constant current circuit supplies a constant base current to the base of the transistor during normal monitoring to keep the transistor on, but when a short circuit is detected, the constant current circuit is activated by a short circuit detection signal from the short circuit detection circuit. The line disconnection control circuit turns off the transistor via the constant current circuit, disconnects the short-circuited output transmission line, and supplies a short-circuit notification signal directly to the fire receiver or via a corresponding repeater. Let it. Further, at the time of short circuit recovery, the line disconnection control circuit activated by the short circuit recovery detection signal from the short circuit recovery detection circuit turns on the transistor via the constant current circuit, thereby reconnecting the output side transmission line that has recovered from the short circuit, and Stop supplying the short-circuit notification signal sent to the fire receiver or the corresponding repeater.
Further, according to the present invention, when a short circuit is detected, the address signal generation circuit supplies an address signal as a short-circuit notification signal to the fire receiver via the transmission line.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; FIG. 1 is a block diagram showing an example of a fire alarm system using the transmission line monitoring device of the present invention. The fire alarm system includes a fire receiver 1, a pair of transmission lines 2 (positive electrode) and 3 (negative electrode), which are a power line and a signal line extending from the fire receiver 1, and the transmission line 2
And at least one pair of branch transmission lines 51 branching from 3
5n and 61 to 6n, transmission line monitoring devices 71 to 7n each having an input side connected to each pair of branch transmission lines 51 and 61, 52 and 62 to 5n and 6n, and transmission line monitoring devices 71 to 7n. A pair of branch transmission lines 81 to 8n and 91 to 9n respectively connected to the output side, and between each pair of output side branch transmission lines 81 and 91 and between 82 and 92 to 8
A plurality of terminals, for example, fire sensors or repeaters 101 to 10n, connected in parallel with each other between n and 9n. Note that the short-circuit notification signals 111 to 11n output from the transmission line monitoring devices 71 to 7n are directly input to the fire receiver 1. Further, the fire receiver 1 and the terminals 101 to 10n each include a transmission unit (not shown) and transmit and receive various signals.

Next, the operation of the fire alarm system configured as described above will be described. During normal monitoring, each of the transmission line monitoring devices 71 to 7n keeps the transmission line conductive, that is, the branch transmission line 51 81, 61 and 91, 52 and 82,
Since 62 and 92 to 6n and 9n are connected, the fire receiver 1 exchanges transmission signals with the terminals 101 to 10n.

Here, if the output side branch transmission lines 82 and 9
When a short circuit occurs between the transmission line monitoring devices 7 and 2, the transmission line monitoring device 7 monitoring the output side branch transmission lines 82 and 92.
2 detects the short circuit and immediately disconnects at least one between the branch transmission lines 52-82 and 62-92. In this case, the transmission line between the fire receiver 1 and the terminal 102 is disconnected, but communication with the other terminals continues. In the conventional fire alarm system, at the time of such a short circuit accident, all the terminals were down, but in the present invention, the communication down was short-circuited by using the transmission line monitoring devices 71 to 7n. It can be limited to only the branch transmission line, and the reliability of the fire alarm system is greatly improved. In addition, the transmission line monitoring device 72 that has detected the short circuit
In addition to disconnecting the short circuits 2, 92, information on the occurrence of a short circuit is sent directly to the fire receiver 1 as a short circuit notification signal 112. Based on this information, the fire receiver 1 displays and prints the monitoring area where the short circuit is detected on the panel. Further, when the recovery from the short circuit occurs, the transmission line monitoring device 72 that detects the recovery from the short circuit not only reconnects the disconnected branch transmission lines 82 and 92, but also outputs the short-circuit notification signal 112 as information on the occurrence of the recovery from the short circuit. To the fire receiver 1 is stopped. When the information and the transmission signal are returned, the fire receiver 1 erases the display of the monitoring area where the short-circuit recovery is detected on the panel and prints the monitoring area. In the case where the fire alarm system shown in FIG. 1 transmits and receives signals between the fire receiver 1 and the terminals 101 to 10n by a polling method, the transmission signal between the terminal 102 and the fire receiver 1 is transmitted. Therefore, the fire receiver 1 displays and prints all the terminals 102 as transmission abnormalities.

FIG. 2 is a block diagram showing an embodiment of the transmission line monitoring apparatus shown in FIG. 1 in more detail. FIG.
Transmission line monitoring devices 71-7n shown in the fire alarm system
Have the same configuration, and only one of them, for example, 72 is shown in FIG. Transmission line monitoring device 72
Is a transistor inserted between the branch transmission lines 52 and 82, for example, a first PNP transistor Q1 (this transistor Q1 can also be inserted between the branch transmission lines 62 and 92); , 62 connected between the base of the transistor Q1 and the negative electrode GND of the stabilized power supply circuit A and connected to the transistor Q1 during normal monitoring. A constant current circuit B for supplying a constant base current; a short-circuit detection circuit C connected between the emitter and the collector of the transistor Q1 for detecting a short circuit between the output-side branch transmission lines 82 and 92; And a short-circuit recovery detection circuit D that is connected between both ends of the stabilized power supply circuit A and detects a short-circuit recovery between the output-side branch transmission lines 82 and 92. The stabilized power supply circuit A, the constant current circuit B, the short circuit detection circuit C, and the short circuit recovery detection circuit D are connected to each other, and are activated by the short circuit detection signal from the short circuit detection circuit C. Is cut off, the output-side branch transmission line that has been short-circuited is cut off, and activated by the short-circuit recovery detection signal from the short-circuit recovery detection circuit D, the constant current circuit B is activated to restart the supply of the base current of the transistor Q1. A line disconnection control circuit E is provided for reconnecting the output-side branch transmission line 82 and the branch transmission line 52 in which the short circuit recovery has occurred by turning on the transistor Q1. At this time, since the output-side branch transmission line 82 has returned from the short-circuit state, connecting the transmission line does not affect other branch transmission lines.

The line disconnection control circuit E further includes a relay (not shown). The relay disconnects the transistor Q1 from the output side branch transmission line 82 when the line disconnection control circuit E is activated by a short circuit detection signal when a short circuit is detected. First relay contact ry1 to be disconnected (this first relay contact ry1 is a break contact and is for protection from noise when the transistor Q1 is off, and is also provided between the branch transmission lines 62 and 92 like the transistor Q1). Can be inserted.) And a second relay contact ry2 (make contact) for transferring information about the short circuit to the fire receiver 1 (FIG. 1).
And a third relay contact ry for holding, which will be described in detail later.
3 (make contact). When the line disconnection control circuit E is activated by the short-circuit recovery detection signal when the short-circuit recovery is detected, the first relay contact ry1 of the above-mentioned relay is activated.
Closes and reconnects the transistor Q1 to the output branch transmission line 82, and the second relay contact ry2 opens to stop supplying the short-circuit notification signal.

The transmission line monitoring device 7 constructed as described above
Operation 2 will be described below. In the normal monitoring state, since the base current is supplied from the constant current circuit B, the transistor Q1 is on, the first relay contact ry1 is closed, and the second relay contact ry2 and the third relay contact ry
3 is open (FIG. 2 shows this state), the branch transmission lines 52 and 82, 62 and 92 are conducting, and the transmission line monitoring device 72 is connected between the output side branch transmission lines 82 and 92. Terminal 102 (FIG. 1).

However, the output side branch transmission line 82,
If a short circuit occurs between the circuits 92 for any reason, the short circuit detection circuit C detects this and sends a short circuit detection signal to the line disconnection control circuit E. Upon receiving the short-circuit detection signal, the line disconnection control circuit E operates and immediately operates the constant current circuit B to cut off the supply of the base current of the transistor Q1. At this time, the transistor Q1 is turned off, and the connection between the output-side branch transmission line 82 and the branch transmission line 52 in which the short circuit has occurred is disconnected. Since this is a disconnection by the transistor Q1, a voltage drop hardly occurs in the branch transmission line 52, and there is no influence of a short circuit to other branch transmission lines. At this time, the line separation control circuit E sends an operation signal to the relay. Therefore, the relay opens the first relay contact ry1 and closes the second relay contact ry2 and the third relay contact ry3. When the short-circuited output-side branch transmission line 82 returns, the short-circuit recovery detection circuit D detects this and sends a short-circuit recovery detection signal to the line separation control circuit E. Since the base current of the transistor Q1 is supplied to the circuit B, the transistor Q1 is turned on, and preparation for reconnecting the output-side branch transmission line 82 and the branch transmission line 52 is made. Further, at this time, the line disconnection control circuit E does not send an operation signal to the relay, so that the first relay contact ry1 is closed and the second relay contact ry2 and the third relay contact ry3 are opened.

FIG. 3 is a circuit diagram of the transmission line monitoring device shown in FIG. The stabilized power supply circuit A is connected between the branch transmission lines 52 and 62, and is composed of, for example, a field effect transistor, a resistor, a Zener diode, a diode, an NPN transistor, and a capacitor as shown in FIG. A voltage V ₀ is generated and the negative electrode is GND.
However, a circuit other than that shown in the figure may be used as long as a stable constant voltage output can be obtained.

The constant current circuit B includes a constant current supply / bias means comprising a field effect transistor Q2, a first resistor R1, and a first Zener diode Z1 connected in series between the emitter of the transistor Q1 and GND. Including. The field effect transistor Q2 and the first resistor R1 constitute a constant current supply means, but are used to suppress fluctuations in current consumption due to voltage fluctuations in the transmission line. , Field effect transistor Q
2 may be omitted and only the first resistor R1 may be used. The constant current circuit B also includes a second resistor R2, a third resistor R3, and a fourth resistor R3 connected in series between both ends of the stabilized power supply circuit A.
And a collector-emitter path of the first NPN transistor Q3 connected in series between the base of the transistor Q1 and GND, and connected to the collector-emitter path for normal monitoring. A first light emitting diode LED1 as a green indicator light indicating a state, a fifth resistor R5 connected to the first light emitting diode LED1, and a second NPN transistor connected to the fifth resistor R5 Q4 comprises a series connection of the collector-emitter path and a first Zener diode Z1 connected between the base of the first NPN transistor Q3 and GND, the base of the second NPN transistor Q4 being the third And a constant current supply means connected to a connection point between the resistor R3 and the fourth resistor R4.

The short-circuit detecting circuit C comprises a sixth resistor R6 and a seventh resistor R7 connected in series between the emitter and the collector of the transistor Q1, and a sixth resistor R6
And a second PNP transistor Q5 having a base connected to the connection point of the seventh resistor R7 and an emitter connected to the emitter of the transistor Q1.

The short-circuit detecting circuit C further includes an eighth resistor R8 and a ninth resistor R9 connected in series between the collector of the second PNP transistor Q5 and GND, and an eighth resistor R8 A third NPN transistor Q6 having a base connected to the connection point of the ninth resistor R9 and an emitter connected to GND, and a tenth transistor Q6 connected in series between both ends of the stabilized power supply circuit A. A positive input terminal connected to the resistor R10 and the second Zener diode Z2, to the collector of the third NPN transistor Q6, and to a connection point between the resistors R2 and R3, the tenth resistor R10 and the second Zener A comparator CM1 having a negative input terminal and an output terminal connected to a connection point with the diode Z2; a positive input terminal of the comparator CM1 and an output-side branch transmission line; And a first diode D1 connected between the two.

The short-circuit recovery detection circuit D includes a stabilized power supply circuit A
11th resistor R1 connected in series between both ends of
1, a second diode D2 and a third diode D3,
And a twelfth resistor R12, a thirteenth resistor R13, and a first resistor R13 connected in series between both ends of the stabilized power supply circuit A.
And a fourth diode D4 and a fifteenth resistor R15 connected in series with each other between the output-side branch transmission line 82 and the twelfth resistor R12. The short-circuit recovery detection circuit D further includes a sixteenth resistor R16 and a fourth resistor R16 connected in series between the output-side branch transmission line 82 and GND.
NPN transistor Q7 (the collector is connected to the sixteenth resistor R16, the base is connected to the connection point of the thirteenth resistor R13 and the fourteenth resistor R14, and the emitter is connected to GND); A + input terminal connected to a connection point between the eleventh resistor R11 and the second diode D2, a − input terminal and an output terminal connected to a connection point between the sixteenth resistor R16 and the collector of the fourth NPN transistor Q7. And a second comparator CM2 having the following.

The line disconnection control circuit E has a third PNP transistor Q8 connected in series between both ends of the stabilized power supply circuit A, and the above-mentioned first to third relay contacts ry1 to ry3. A parallel connection of the relay RY and the fifth diode D5, a second light-emitting diode LED2 as a red indicator light indicating a disconnected state,
And a fifth NPN transistor Q9 and a third PN transistor Q9.
A seventeenth resistor R17 connected between the emitter and base of the P-type transistor Q8, connected between the base of the third PNP transistor Q8 and the output terminal of the first comparator CM1 in the short-circuit detection circuit C. The eighteenth resistor R1
8 and the twelfth output terminal and the twelfth
A sixth diode D6 connected between the resistor R12 and the connection point of the thirteenth resistor R13, a twentieth resistor R20 connected between the emitter and the base of the fifth NPN transistor Q9, And the fifth NPN transistor Q
Nineteenth resistor R connected between the base of the second comparator 9 and the output terminal of the second comparator CM2 in the short-circuit recovery detection circuit D
19 inclusive.

Here, the principle of short-circuit detection by the short-circuit detection circuit C will be described with reference to FIG. The relationship between the transmission current (collector current) flowing through the transistor Q1 and the emitter-collector voltage of the transistor Q1 is as shown in FIG. 4 because the transistor Q1 is driven by the constant current circuit B with a constant base current. . Here, the current value I _SUS transmission current becomes substantially constant, flow on the fire receiver 1 (FIG. 1) of the short-circuit detection current value I _MAX and the transmission line monitoring device 72 connected to the terminal 102 (FIG. 1) Maximum current consumption I _SM
And the terminal 102 has the maximum current consumption I _SM
The base current is selected so that the maximum voltage drop V _CEM between the emitter and the collector of the transistor Q1 when the current flows does not affect the transmission. Next, the threshold value V _{S at} which the short circuit detection circuit C detects a short circuit is determined by the maximum voltage drop V
The minimum voltage V between the emitter and the collector of the transistor Q1 when the short circuit occurs because the maximum wiring resistance is larger than the _CEM and the maximum wiring resistance exists on the output side branch transmission lines 82 and 92 as described above.
Choose to be less than _MIN . That is, as shown in FIG.

V _CEM <V _S <V _MIN (= Transmission voltage of fire receiver 1−I _SUS × Maximum wiring resistance)

## EQU1 ## Threshold value V _S satisfying this condition
Then, the condition that the voltage between the output side branch transmission lines 82 and 92 becomes maximum at the time of short circuit, that is, the output side branch transmission line 82,
Even if a short circuit occurs between the terminals 92 via the maximum wiring resistance, the short circuit can be reliably detected.

For example, a transmission voltage of 36 V DC, a short-circuit detection current value I _{MAX of the} fire receiver 1 = 1.2 A, and a maximum wiring resistance of 30
Ω, when the maximum current consumption value I _SM = 0.5 A of the terminal device 102, I _SUS = 0.5 A <I _SUS <1.2 A
Set to 1A. At this time

V _MIN = DC36V-1A × 30Ω = 6V

## EQU1 ## On the other hand, if it is assumed that the maximum voltage drop V _CEM = 0.2 V between the emitter and the collector when the maximum current consumption of the terminal device 102 flowing through the transistor Q1 is 0.5 A, the threshold value V _{S for} short-circuit detection is as follows. You can select it.

0.2 V <V _S <6 V

According to such a short-circuit detection method, the reduction of the transmission voltage due to the short-circuit is limited only to the output side of the transmission line monitoring device 72 that has detected the short-circuit, and does not affect other transmission lines.

A specific example of the short-circuit detecting circuit C includes a sixth resistor R6, a seventh resistor R7, and a second PN as shown in FIG.
The second PNP transistor Q5 has an emitter-base voltage equal to the emitter-collector voltage of the transistor Q1 × R.
6 / (R6 + R7). The value of the sixth resistor R6 and the seventh resistor R7 is equal to the value of the second PNP transistor Q.
The emitter-collector voltage of 1 is short circuit detection threshold V
_{When the} voltage exceeds _S , the second PNP transistor Q5 turns on, that is,

V _S × R 6 / (R 6 + R 7) = 0.6 V (Emitter to turn on the second PNP transistor Q 5
Voltage between bases)

The second PNP transistor Q5 is set to supply a base current that can output a signal current to the line disconnection control circuit E.

In this embodiment, the transistor Q1
Although the base current of the transistor Q1 has been described as being constant, means for switching the base current of the transistor Q1 according to the current consumption of the terminal 102 monitored by the transmission line monitoring device 72 may be provided. However, even in that case, the above conditions must be satisfied.

Next, the transmission line monitoring device 72 shown in FIG.
Will be described in detail with reference to the time chart of FIG. When power is applied at time t1, stabilized power supply from the circuit A is a constant voltage V ₀ is supplied to each circuit B to E, R2, biasing means comprising a R3 and R4 are a second NPN-type in the constant current circuit B Since the transistor Q4 is forward biased, the second NPN transistor Q4 turns on. In addition, the first Zener diode Z1 has Q2 and R
The first NPN transistor Q3 is also turned on because the current is supplied from the constant current supply means composed of 1 and the Zener voltage _VZ1 is output. Therefore, the transistor Q1 is kept constant by the constant current supply means including the first NPN transistor Q3, the first light emitting diode LED1, the fifth resistor R5, the second NPN transistor Q4 and the first Zener diode Z1. It is turned on because the base current is supplied. Also, the first light emitting diode LED1
Also turns green to indicate that no short circuit has occurred between the output-side branch transmission lines 82 and 92.

The current value of the constant current supply means consisting of Q3, LED1, R5, Q4 and Z1, ie, the transistor Q1
The base current I _B is shown by the following equation.

I _B = (V _Z1 −V _BE (Q3) −V _F (LED
1) -V _CE (Q4)) / R5

Here, V _Z1 is the Zener voltage of the first Zener diode Z1, V _BE (Q3) is the base-emitter voltage of the first NPN transistor Q3, and V _F (LE
D1) is the forward voltage of the first light emitting diode LED1, and V _CE (Q4) is the collector-emitter voltage of the second NPN transistor Q4.

At the time of normal monitoring, the transistor Q1 is on and only a voltage of, for example, about 0.3 V is generated between the emitter and the collector of the transistor Q1.
Since the P-type transistor Q5 is off, it does not output a short-circuit detection signal. Since the short-circuit detection signal is not input, the third NPN transistor Q6 is off. At this time, if a load resistance _RL having a predetermined resistance value exists between the output-side branch transmission lines 82 and 92 (non-short-circuit state), the voltage on the output-side branch transmission line 82 is higher than the constant voltage V _0. first the voltage at the positive input terminal of the comparator CM1, the constant voltage V ₀ ho Isuzu resistance value and the third second resistor R2 for
And the sum of the resistance values of the resistor R3 and the fourth resistor R4, the voltage at the-input terminal of the first comparator CM1, that is, the Zener voltage VZ2 of the second Zener diode _Z2 (this _VZ2 Is lower than the constant voltage V ₀ and lower than the voltage at the + input terminal of the first comparator CM1.)
Therefore, the first comparator CM1 outputs an H level to its output terminal. Note that, instead of the second zener diode Z2, a circuit that generates the voltage _VZ2, for example, a circuit in which a plurality of diodes (not shown) are connected in series may be used.

Since this H level reverse biases the third PNP transistor Q8, the third PNP transistor Q8 is off, so that the relay RY remains demagnetized and its first relay contact ry1 is in a closed state (there is conduction between the branch transmission lines 52 and 82), and the second relay contact ry2 and the third relay contact ry3 remain open. Further, the twelfth resistor R12, the thirteenth resistor R13, and the fourteenth resistor R14 in the short-circuit recovery detection circuit D forward bias the fourth NPN transistor Q7.
The type transistor Q7 is on, so that the voltage applied from the stabilized power supply circuit A to the + input terminal of the second comparator CM2 through the eleventh resistor R11, for example, about 1.2
V is the ON fourth NPN transistor Q described above.
7, the second comparator CM2 outputs an H level to its output terminal because the voltage is higher than the voltage of 0 V applied to the minus input terminal of the second comparator CM2 through the H level. Turns on.

However, the output side branch transmission line 82,
If the load 92 is completely short-circuited at time t2 and the resistance value of the load resistance _RL becomes 0, the output branch transmission line 8
Since the current flowing between the transistors 2 and 92 increases rapidly and the base current of the transistor Q1 is fixed, the voltage between the collector and the emitter of the transistor Q1 increases so as to approach the voltage supplied by the branch transmission lines 52 and 62. Therefore, the second PNP transistor Q in the short-circuit detection circuit C
5 when the emitter-base voltage is V _EB (Q5)
(Eg, 0.6 V), the emitter-collector voltage V _EC (Q1) of the transistor Q1 becomes

V _EC (Q1) = (R6 + R7) / R6 · V _EB (Q5)

When the voltage exceeds the voltage satisfying the condition (2), the second PN
Since the P-type transistor Q5 is turned on at time t2 and outputs a short-circuit detection signal, the third NPN-type transistor Q5
6 also turns on. This third NPN transistor Q6
Is turned on, the third resistor R3 and the fourth resistor R4 in the constant current circuit B are short-circuited, the voltage applied between the resistors R3 and R4 is forcibly reduced, and the second NPN transistor Q4 is turned off. The second NPN transistor Q4 is turned off because no base current is supplied to keep it on. When the second NPN transistor Q4 is turned off, the first NPN transistor Q3 is also turned off. As a result, the above-described constant current supply means can no longer be configured, and the base current to the transistor Q1 cannot be supplied. , The transistor Q1 is also turned off, and the first light emitting diode LED1 is turned off.

When the transistor Q1 is turned off, the connection between the branch transmission lines 52 and 82 is opened. The sixth
The emitter and the collector of the transistor Q1 are connected by the resistor R6 and the seventh resistor R7.
And the seventh resistor R7 both have a resistance value of several kilohms or more, so that the output side branch transmission lines 82 and 92 are in the same state as the state where they are separated. Further, when the third NPN transistor Q6 is turned on, the voltage at the + input terminal becomes 0 V lower than the voltage at the-input terminal, so that the output of the first comparator CM1 becomes L level, and 3 P
The NP transistor Q8 is turned on. When the output of the first comparator CM1 goes low, a fourth N
The PN transistor Q7 is turned off because the forward bias is no longer applied, but since the output-side branch transmission lines 82 and 92 are short-circuited, the sixteenth resistor R16 is connected to the minus input terminal of the second comparator CM2. 0V is applied via
The output of the second comparator CM2 remains at the H level. As a result, short-circuited by closing the second relay contact ry2 with completely decouple the branch transmission lines 52 and 82 by opening a set time T _S completion time t3 the first relay contact ry1 relay RY is energized The third NPN transistor Q6 is kept on by sending the transfer signal 112 (FIG. 1) to the fire receiver 1 and closing the third relay contact ry3. At the same time, the second light-emitting diode LED2, which is a line separation indicator, is turned on.

Next, when the output side branch transmission lines 82 and 92 are short-circuited and restored at time t4, that is, when the load resistance _RL exceeds a predetermined resistance value, the constant voltage V ₀ of the stabilized power supply circuit A is set.
Is applied to a series circuit including the fifteenth resistor R15, the fourth diode D4, and the load resistor _RL, so that a voltage is generated across the load resistor _RL . When this voltage increases, that is, when the voltage at the + input terminal of the second comparator CM2 becomes lower than the voltage at the-input terminal, the output of the second comparator CM2 becomes L level,
Supplies the short-circuit recovery detection signal, thereby turning off the fifth NPN transistor Q9. As a result, the short-circuit by opening the second relay contact ry2 with relay RY reconnects the branch transmission lines 52 and 82 by closing the first relay contact ry1 that are demagnetized at the reset time T _R completion time t5 By stopping the supply of the transfer signal and opening the third relay contact ry3, the third NPN transistor Q6 is turned off. When the third NPN transistor Q6 is turned off, the forward bias of the second NPN transistor Q4 is restored, and the second NPN transistor Q4, and thus the first NPN transistor Q4, is turned off.
NPN transistor Q3 and transistor Q1 are turned on. Further, since the output of the first comparator CM1 goes high when the third NPN transistor Q6 is turned off, the third PNP transistor Q8 is turned off. Thus, the transmission line monitoring device 72 returns to the state at the time of normal monitoring.

FIG. 6 is a block diagram showing another example of a fire alarm system using the transmission line monitoring apparatus of the present invention. This fire alarm system includes a fire receiver 1 and a pair of transmission lines 2 and 3 similarly to the fire alarm system of FIG. 1, and is further inserted in series with these transmission lines 2 and 3, and transmission line monitoring devices 71 to 71. 7n and at least one set of units U1 to Un consisting of a plurality of terminals 101 to 10n connected in parallel at the output side of the transmission line monitoring device.

When a short circuit occurs between the transmission lines 2 and 3 on the output side of the transmission line monitoring device 72, the transistor Q1 (FIG. 2) in the transmission line monitoring device 72 is turned off as described above. Then, at least one of the transmission lines 2-2 and 3-3 is disconnected, and the second relay contact ry2 (FIG. 2) in the transmission line monitoring device 72 is closed, whereby the short-circuit notification signal 112 is directly transmitted. , Sent to the fire receiver 1. Next, when the short circuit is restored between the transmission lines 2 and 3 on the output side of the transmission line monitoring device 72, the transistor Q1 in the transmission line monitoring device 72 is turned on, and the first relay contact ry1 (FIG. 2). Is closed, the disconnected transmission line is reconnected, and the transmission line monitoring device 7
The transmission of the short-circuit notification signal 112 to the fire receiver 1 is stopped by the opening of the second relay contact ry2 in 2.

FIG. 7 is a block diagram showing still another example of a fire alarm system using the transmission line monitoring apparatus of the present invention. In this fire alarm system, at least one repeater 41 to 4 m is provided in the fire alarm system of FIG. Each of the repeaters 41 to 4m is connected between the transmission lines 2 and 3, and for example, each of the four transmission line monitoring devices 71, 72,.
., 7n short-circuit transfer signals 111A, 112A,.
-It is configured to receive 11 nA and to exchange various signals.

When a short circuit occurs between the output side branch transmission lines 82 and 92, the transmission line monitoring device 72 which has detected this short circuit immediately connects at least one of the branch transmission lines 52-82 and 62-92. It disconnects and sends the short circuit transfer signal 112A to the repeater 41. Then, the repeater 41 notifies the fire receiver 1 of the content of the short-circuit notification signal 112A through the transmission lines 2 and 3 by the transmission signal. The fire receiver 1 displays and prints a monitoring area where a short circuit is detected on the board based on information from the repeater 41. The fire alarm system shown in FIG. 7 includes the fire receiver 1, the repeaters 41 to 4m, and the terminal 10
In the case of transmitting and receiving a signal between 1 and 10n by the polling method, the transmission signal between the terminal 102 and the fire receiver 1 is interrupted.
Are displayed and printed even if all are transmission abnormalities. When the short circuit is restored between the output side branch transmission lines 82 and 92,
The transmission line monitoring device 72 that has detected the recovery from the short circuit reconnects the disconnected branch transmission lines 52 and 82 and stops sending the short circuit transfer signal 112A to the repeater 41. The fire receiver 1 returns the information and the transmission signal via the repeater 41 to erase the display of the monitoring area where the recovery from the short circuit is detected on the board, and print the monitoring area.

FIG. 8 is a block diagram showing another example of a fire alarm system using the transmission line monitoring apparatus of the present invention. The fire alarm system includes a transmission line monitoring device 71 as shown in FIG.
To 7n to fire receiver 1
Instead, the different address signals generated as short-circuit notification signals in the transmission line monitoring devices 71A to 7nA are transmitted through the branch transmission lines 51 to 5n and 61 to 6n and the transmission lines 2 to 3 to the fire receiver. It is intended to be sent to 1.

More specifically, FIG. 9 is a block diagram showing another embodiment of the transmission line monitoring device of the present invention. This transmission line monitoring device 72A has the same components as those of the transmission line monitoring device 72 of FIG. And an address signal generating circuit F connected in parallel with the stabilized power supply circuit A and activated by closing the second relay contact ry2. When the address signal generating circuit F is operated as described above,
A signal having a different frequency, for example, a unique frequency is generated for each of the transmission line monitoring devices 71A to 7nA, and this signal is sent to the fire receiver 1 as an address signal as described above. Then, the fire receiver 1 discriminates which transmission line monitoring device has been activated by discriminating the received frequency signal, and performs display or the like. At the time of recovery from the short circuit, the supply of the address signal is stopped.

The transistors Q1 and Q5 are PNP
Although the transistor is provided at the positive electrode of the transmission line, the transistor may be provided at the negative electrode of the transmission line as an NPN transistor.

When a relay is used in the main circuit, the operation speed when the relay is impressed is usually several milliseconds to several tens of milliseconds.
The response speed is extremely fast, which is less than m seconds. If the transmission line is short-circuited, it is better to disconnect the short-circuited portion as short as possible in order to minimize damage to the fire receiver or fire sensor caused by the short-circuit. This is the reason we used it.

[0051]

As described above in detail, the transmission line monitoring device of the fire alarm system according to the present invention comprises a pair of transmission lines, which are a power line and a signal line extending from a fire receiver, or a pair of these transmission lines. A transistor inserted into at least one of a transmission line pair or a branch transmission line pair on the input side of the transmission line monitoring device, for monitoring a short circuit and a recovery from the short circuit of at least one pair of branched transmission lines; and a base of the transistor. And a constant current circuit that supplies a constant base current, and is connected between the emitter and the collector of the transistor, and when the voltage between the emitter and the collector exceeds a predetermined value, the output-side transmission line is short-circuited. A short-circuit detection circuit that detects and generates a short-circuit detection signal; and a load resistance connected between the output-side transmission line and the output-side transmission line having a predetermined resistance. Exceeds, the short circuit recovery detection circuit that detects that the output side transmission line has recovered from the short circuit and generates a short circuit recovery detection signal, and is connected to the short circuit detection circuit and the short circuit recovery detection circuit, and the short circuit detection signal When activated by the constant current circuit, the transistor is turned off, thereby disconnecting the output side transmission line, and when activated by the short-circuit recovery detection signal,
Turning on the transistor through the constant current circuit,
Since a line disconnection control circuit for reconnecting the output side transmission line is provided, even if the line voltage does not decrease due to a short circuit accident via high resistance, a short circuit can be detected without fail, and a short-circuited transmission can be performed. There is no influence of voltage drop due to short circuit other than the line, and the disconnection operation is very fast, so that the reliability of the system is greatly improved, and the power of the fire receiver is not restarted when the short circuit is recovered There is an effect that the transmission line can be reconnected by the transmission line monitoring device itself.

In addition, the line disconnection control circuit may supply a short-circuit notification signal to the fire receiver directly or via a corresponding relay, or the address signal generation circuit activated upon detection of the short-circuit Since the address signal as the short-circuit notification signal is supplied to the fire receiver via a transmission line, the fire receiver can perform required processing based on the short-circuit notification signal or the address signal. Play.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a fire alarm system using a transmission line monitoring device according to the present invention.

FIG. 2 is a block diagram showing an embodiment of the transmission line monitoring apparatus shown in FIG. 1 in more detail;

FIG. 3 is a circuit diagram of the transmission line monitoring device shown in FIG. 2;

FIG. 4 is a diagram illustrating the principle of short-circuit detection.

FIG. 5 is a time chart for explaining the operation of the transmission line monitoring device shown in FIG. 3;

FIG. 6 is a block diagram showing another example of a fire alarm system using the transmission line monitoring device according to the present invention.

FIG. 7 is a block diagram showing still another example of a fire alarm system using the transmission line monitoring device according to the present invention.

FIG. 8 is a block diagram showing another example of a fire alarm system using the transmission line monitoring device according to the present invention.

FIG. 9 is a block diagram showing another embodiment of the transmission line monitoring device shown in FIG. 8 in more detail;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fire receiver 2,3 Transmission line 41-4m Repeater 51-5n, 61-6n, 81-8n, 91-9n
Branch transmission line 71-7n, 72A Transmission line monitoring device 101-10n Terminal device 111-11n Short circuit transfer signal Q1 Transistor A Stabilized power supply circuit B Constant current circuit C Short circuit detection circuit D Short circuit recovery detection circuit E Line separation control circuit F Address signal generating circuit RY Relay ry1, ry2, ry3 First, second, third relay contact

Continuation of front page (56) References JP-A-62-21347 (JP, A) JP-A-61-70294 (JP, U) JP-A-49-92184 (JP, U) JP-A-62-117688 (JP, U) , U) (58) Fields studied (Int. Cl. ⁷ , DB name) G08B 17/00

Claims (7)

(57) [Claims] 1. A fire receiver, a pair of transmission lines extending from the fire receiver as a power line and a signal line, and at least a pair of branch transmission lines branched from these transmission lines.
A transmission line monitoring device connected between each pair of branch transmission lines, a pair of branch transmission lines on the output side of the transmission line monitoring device, and a plurality of parallel connection between the output side branch transmission lines; In a fire alarm system including a terminal device, the transmission line monitoring device includes: a transistor inserted into at least one of the pair of branch transmission lines; a transistor connected to a base of the transistor; A constant current circuit for supplying a current, connected between an emitter and a collector of the transistor,
When the voltage between the emitter and the collector exceeds a predetermined value, a short-circuit detection circuit that detects that the output-side branch transmission line is short-circuited and generates a short-circuit detection signal; When the load resistance between the side branch transmission lines exceeds a predetermined resistance value, a short circuit recovery detection circuit that detects that the output side branch transmission line has recovered from a short circuit and generates a short circuit recovery detection signal; Connected to the short-circuit recovery detection circuit, and when activated by the short-circuit detection signal, turns off the transistor through the constant current circuit, thereby disconnecting the output-side branch transmission line, and A line disconnection control circuit that, when activated, turns on the transistor via the constant current circuit and thereby reconnects the output branch transmission line. Transmission line monitoring device of a fire alarm system, which comprises a. 2. A fire receiver, a pair of transmission lines extending from the fire receiver as a power line and a signal line, inserted in series with the transmission lines, and provided with a transmission line monitoring device and the transmission line monitoring device. A fire alarm system comprising: at least one set of a plurality of terminals connected in parallel to each other on the output side of the fire alarm system. An inserted transistor, a constant current circuit connected to a base of the transistor and supplying a constant base current, connected between an emitter and a collector of the transistor,
When the voltage between the emitter and the collector exceeds a predetermined value, a short-circuit detection circuit that detects that the transmission line on the output side is short-circuited and generates a short-circuit detection signal; When the load resistance between the lines exceeds a predetermined resistance value, a short-circuit recovery detection circuit that detects that the output-side transmission line has recovered from the short-circuit and generates a short-circuit recovery detection signal; When connected to a detection circuit and activated by the short circuit detection signal, the transistor is turned off via the constant current circuit, thereby disconnecting the output side transmission line, and when activated by the short circuit recovery detection signal, A line disconnection control circuit that turns on the transistor via the constant current circuit and thereby reconnects the output side transmission line. Transmission line monitoring apparatus of the alarm system. 3. A fire receiver, a pair of transmission lines extending from the fire receiver as a power line and a signal line, at least one repeater connected between the transmission lines, and the transmission line , A transmission line monitoring device connected between each pair of branch transmission lines, a pair of branch transmission lines on the output side of the transmission line monitoring device, and these output side branch transmission lines. In a fire alarm system comprising a plurality of terminals connected in parallel between each other, the transmission line monitoring device, a transistor inserted into at least one of the pair of branch transmission lines, A constant current circuit connected to a base of the transistor and supplying a constant base current; connected between an emitter and a collector of the transistor;
When the voltage between the emitter and the collector exceeds a predetermined value, a short-circuit detection circuit that detects that the output-side branch transmission line is short-circuited and generates a short-circuit detection signal; When the load resistance between the side branch transmission lines exceeds a predetermined resistance value, a short circuit recovery detection circuit that detects that the output side branch transmission line has recovered from a short circuit and generates a short circuit recovery detection signal; Connected to the short-circuit recovery detection circuit, and when activated by the short-circuit detection signal, turns off the transistor through the constant current circuit, thereby disconnecting the output-side branch transmission line, and A line disconnection control circuit that, when activated, turns on the transistor via the constant current circuit and thereby reconnects the output branch transmission line. Transmission line monitoring device of a fire alarm system, which comprises a. 4. A transmission line on an input side of the transmission line monitoring device.
A stabilized power supply circuit connected between the pair of roads.
A current circuit is connected across the stabilized power supply circuit.
And the positive electrode of the input-side transmission line pair and the transistor
Connected to the base of the transmission line monitoring device.
During normal monitoring of the transmission line pair on the
Source current to keep the transistor on
However, when a short circuit is detected, the base current of the transistor
2. The transistor according to claim 1, wherein the supply is cut off to turn off the transistor.
A transmission line monitoring device for the fire alarm system of any of Ishi 3 above. 5. The transistor according to claim 1 , wherein
A series connection between the emitter and collector of
Sixth and seventh resistors and connection of the sixth and seventh resistors
The base connected to the point and the emitter of the transistor
Second PNP-type transformer having an emitter connected to the
4. A device according to claim 1, wherein said first and second resistors are connected to each other.
Transmission line monitoring equipment for some fire alarm systems. 6. The short circuit control circuit according to claim 1 , wherein
No first relay contact when activated by detection signal
Driving a relay having a third relay contact to
Open the first relay contact inserted in series with the transistor.
This ensures that the output side transmission line is disconnected and
Closing the second relay contact
Receiving the fire directly to the receiver or via a corresponding repeater
4. The method according to claim 1, wherein a short-circuit notification signal is supplied to the transceiver.
Transmission line monitoring equipment for some fire alarm systems. 7. A transmission line on an input side of the transmission line monitoring device.
And a stabilized power supply circuit connected in parallel between
A dress signal generating circuit, wherein the constant current circuit is
Connected in parallel with the stabilized power supply circuit and
Also connected to the positive electrode of the transmission line pair and the base of the transistor.
The transmission line pair on the output side of the transmission line monitoring device.
During normal monitoring, supply base current to the transistor.
To keep the transistor on, but when a short circuit is detected
Cuts off the supply of base current to the transistor and
Turn off the transistor and set the address signal generation
The path is activated when a short circuit is detected, and connects the input side transmission line pair.
Via the address as a short-circuit notification signal to the fire receiver
4. A transmission line monitoring device for a fire alarm system according to claim 1, which supplies a signal .