JPH0353795A - Malfunction detecting system - Google Patents

Abstract

PURPOSE:To speedily reset the call state of a subscriber circuit by displaying the detection of malfunction in a PNPN switch at the time of feeding normally to a host controller in the malfunction detecting system of a switch circuit provided in the subscriber circuit of a telephone exchange. CONSTITUTION:A switch circuit 4 is equipped with a PNPN switch 4a, which supplies and connects a call current to a subscriber line and switches a voltage polarity to be impressed to the subscriber line, and a PNPN switch 4b to insert and connect a resistor 6 between A and B lines at the time of feeding to a facsimile equipment and a data telephone set. When the malfunction is generated in the switch 4b, an almost '0'V is impressed to the input of a comparator 8 in a malfunction detection display circuit 7 and an output comes to a negative voltage. Then, this negative voltage becomes smaller than the value of a referring voltage 12 and the output of a comparator 9 goes to a high level and is impressed to an AND incoming path 10. At such a time, for the input of another signal to the AND circuit 10, a normal feeding signal is set to a high level, a preloop switch signal is set to a low level and a feeding stop signal is set to the low level. Then, AND is established and a malfunction detection display output is set in a latch circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application) The present invention relates to a subscriber circuit of a telephone or switchboard, and more specifically, to a malfunction detection method for detecting malfunction of a switch circuit included in the subscriber circuit. .

(Prior art) The first switch circuit constituting the switch circuit of the subscriber circuit
The PN switch is used during normal power supply (normal telephone terminal supply!
), connect the output of the feeder circuit to the subscriber line, and connect the A of the subscriber edge.
Batteries on the wire. Supply earth air to line B. Also. At the time of reverse power supply, the structure is such that earth air is supplied to subscriber line A, and battery is supplied to subscriber line B.

The second PNPN switch is turned on together with the first PNPN switch when power is being supplied to a facsimile or data telephone.
H. A resistor is connected to the subscriber line, and the power supply circuit is configured to supply constant voltage power, with the battery being supplied to the A line and the earth's air being supplied to the B line.

(Problem to be Solved by the Invention) By the way, the conventional switch circuit uses AV to prevent malfunction of the second PNPN switch during normal power supply.
I used a PN switch to a high P of 7atitt.

This PNPN switch with high dv/dt tolerance. dv/
The erroneous ignition characteristic is defined as the dt tolerance to prevent erroneous ignition due to sudden voltage changes occurring at the subscriber m4Ja.

However, a sudden voltage change occurring on the subscriber line side may exceed the dv/dt tolerance of the PNPN switch, considering lightning surges and other dv/dtt effects. Spouted, P
In some cases, an erroneous pulse induced by noise or the like is superimposed on the NPN switch drive signal line, and malfunctions of the PNPN switch cannot be completely prevented. We met, PNP
Once the N switch is ignited incorrectly, it will disturb the normal operation of the subscriber circuit for a long time since it has a current holding function. Conventionally, in such cases, the malfunction was detected and
Since this information was not displayed, there was a drawback in that it was difficult to take immediate countermeasures.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks, and to provide a malfunction detection system that can detect and display a malfunction in a switch circuit of a subscriber circuit.

(Means for Solving the Problems) In order to achieve the above object, the malfunction detection method according to the present invention connects the subscriber terminal to the subscriber terminal by the A line and B line of the 2i type subscriber base, and connects the subscriber terminal between the A line and the B line. The first PNPN switch switches the polarity of the applied voltage seven times, and the high-resistance connection is used to form a DC loop when connecting a non-ringing terminal such as a facsimile or data telephone. a! a switch circuit comprising a second PNPN switch for performing . A subscriber circuit of a telephone exchange has a power supply circuit that supplies earth air and batteries to the switch circuit and monitors the loop state between the A line and the B line. a first comparator for detecting a voltage across the second PNPN switch; a second comparator that compares the output of the M1 comparator with a predetermined reference voltage, and a logic that receives as input the second comparator output, a normal power supply signal, a pre-loop switch-on signal, and a power supply stop signal. A malfunction detection circuit consisting of a product circuit and a latch circuit that holds the output of the AND circuit is provided. During normal power supply, the pre-loop switch signal is off. And if the power supply is not stopped,
When the second PNPN switch 1 malfunctions and the voltage between the terminals of the second PNPN switch becomes approximately oV, the latch circuit is configured to output a malfunction detection signal.

(Example) below. The present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a block circuit diagram showing an embodiment of a subscriber circuit to which a malfunction detection method according to the present invention is applied. The switch circuit 4 is connected to the subscriber terminal IK via the A line 2 and Bm3 of the two-wire subscriber line. The other end is connected to the power supply circuit 5.

When switching the polarity of the voltage applied to subscriber 1i1K and supplying power to facsimile and data telephones, A line 2 and B, i
A resistor (high resistance) RNN6 is connected between i3 and a DC loop is formed. This switch circuit 4 is connected to a first OPNPN switch 4a for supplying communication current to the subscriber line, and for switching the voltage polarity applied to the subscriber line. , Insert and connect resistor 6 between the H wires #! It has a 20PNPN switch 4b.

The power supply circuit 5 is equipped with a ground voltage and a battery, and supplies communication current as well as the AIIs 2 and B lines 3 of the subscriber lines.
Monitor the state of the loop between.

The malfunction detection display circuit 7 includes a second I) first comparator 8 which detects the voltage between the terminals of the N P N switch 4b. The output of the comparison circuit of K1 and the reference voltage value 12 (Vref) t-
AND circuit 10b and AND circuit 1 which receive the second comparator 9 to be compared, the output of the second comparator 9, the normal power supply signal, the pre-loop switch-on signal, and the power supply stop signal as inputs.
The latch circuit 11 is connected to a higher-level control device (not shown) and sends a malfunction detection display output to the device.

When supplying power to facsimiles and data telephones, subscriber line A
A second PN that connects a resistor RNN6 between line 2 and B line 3.
The voltage between the terminals of the PN switch 4b is about O volts when the second PNPN switch 4b is on, and the voltage between the terminals of the second PNP switch 4b is about O volts.
When the NPN switch is off, subscriber lines A2 and B
It is equal to the voltage across wire 3.

During normal power supply. A normal power supply signal is applied to the switch circuit 4, and the first PNPN switch 4a-1 and 4a
-4 is in the on state, the battery is supplied to the A line of the subscriber line connected to the telephone which is the subscriber terminal 1, and the earth is supplied to the B line.

At this time, the second PNPN switch 4b is off. A negative voltage (-48V) is applied to the inverting input terminal of the first comparator 8.
) is applied. Therefore, the output of the first comparator 8 is a positive voltage, and the output of the second comparator 9 is a negative voltage. Since the output of the AND circuit 10 is at a low level, the latch circuit 11 does not display the malfunction detection.

Here, if an erroneous pulse induced by noise etc. is superimposed and the second PNPN switch 4b malfunctions, approximately 0■ is applied to the input of the first comparator 80, so the first comparator 80 The output of is a negative voltage, and this negative voltage is the reference voltage l2
When the value of is 9 smaller than the value of , the output of the second comparator 9 becomes a high level and is applied to the logical product path 10.

At this time, the other signal input to the AND circuit 10 is /-MAL! The signal is at high level, the pre-roof switch signal is at low level, and the power supply stop signal is at low level, and the logical product is established. A malfunction detection display output is set in the latch circuit l1.

(Effects of the Invention) As explained above, the present invention provides a facsimile. A comparator detects the voltage across the second PNPN switch that is turned on when power is supplied to the data telephone, and an AND circuit detects the voltage across the second PNPN switch.
Detects PN switch malfunction conditions. Since the upper control device is configured to display the detection of malfunction of the PNPN switch during normal power supply, the upper control device can detect malfunction of the PNPN switch and immediately reset the call status of the subscriber circuit. It is possible to supply appropriate communication current to subscriber terminals. Therefore, unnecessary current consumption on subscriber lines can be suppressed. This has the effect of improving service to subscribers.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of the malfunction detection method according to the present invention. 1...Subscriber terminal 2...Subscriber line A. iiiI
3... BM of subscriber line 4... Switch circuit 4a
...First PNPN switch 4b...Second PNPN switch 5...Power supply circuit 6...Resistor (approximately NN) 7...
Malfunction detection display circuit 8...first comparison circuit 9...second comparison circuit 1
0...Logic product circuit 1l...Latch circuit 12...
・Reference voltage

Claims (1)

[Claims] The first PNPN switch is connected to the subscriber terminal by the A and B lines of the two-wire subscriber line and switches the polarity of the voltage applied between the A and B lines, as well as the non-ringing switch for facsimiles, data telephones, etc. a switch circuit comprising a second PNPN switch that performs a high resistance connection to form a DC loop when terminals are connected, and a loop between the A line and B line that supplies earth air and a battery to the switch circuit; In a subscriber circuit of a telephone exchange having a power feeding circuit for monitoring a state, a first comparator detecting a voltage across the second PNPN switch, and an output of the first comparator and a predetermined reference voltage. a second comparator that compares the output of the second comparator, an AND circuit that receives the output of the second comparator, a normal power supply signal, a pre-loop switch on signal, and a power supply stop signal, and a latch that holds the output of the AND circuit. a malfunction detection circuit consisting of a circuit is provided, and when the pre-loop switch signal is off and the power supply is not stopped during normal power supply, the second PNPN switch malfunctions and the second PNPN
A malfunction detection system characterized in that the latch circuit outputs a malfunction detection signal when the voltage between the switch terminals reaches approximately 0V.