JP2653039B2 - Communication line remote disconnection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-wire communication line, and more particularly, is inserted between a high-speed communication line such as ISDN and a terminal device.
The present invention relates to a communication line remote disconnection device that separates a communication line from a terminal device by performing remote control through a communication line from a central office.

[0002]

2. Description of the Related Art In a telephone facility or the like, when a failure occurs, it is necessary to separate the communication line from the terminal device in order to confirm whether the failure is on the communication line side or the terminal device side. In order to separate the communication line, a communication line separation operation circuit, a power supply for the operation, and a control DC current detection resistor inserted through the communication line are required.

Since the disconnecting device is configured as described above, the detecting resistor for controlling the operating power supply of the communication line separating operation circuit has an effect on the communication current in the communication state. Or cause imbalance in the line. Further, when the output voltage of the operating power supply fluctuates according to the operating conditions, it is necessary to take measures such as preventing an error operation of the circuit.

[0004]

The device for separating the communication lines has already been put into practical use, and consideration has been given to alleviation of the above-mentioned problems. However, ISDN
However, when applied to high-speed communication lines such as those described above, there is a problem that the measures cannot be said to be sufficient.

[0005] The present invention solves the above-mentioned problems, and ensures reliable operation by simple and easy operation even if the type of communication line, the type of terminal device connected to this communication line, and the operation state thereof are various. It is an object of the present invention to provide a communication line remote disconnection device capable of performing the following.

[0006]

To achieve the above object, the present invention is connected between two-wire communication lines, and operates by a control DC voltage of a certain value or more applied to the communication lines, A first power supply circuit that outputs a predetermined voltage; and a second power supply circuit that outputs a predetermined voltage only when a control DC current having a constant value is supplied to the communication line. A timer circuit including a time constant circuit including a capacitor for a timer and a resistor for monitoring the duration of the output voltage, which is operated by an output voltage of one of the second power supply circuits, and a communication line; A communication line disconnection operation circuit configured to control a switching relay to be separated and a communication line disconnection operation circuit configured to disconnect a communication line, wherein the second power supply circuit includes: For detecting DC current for control A detection resistor inserted in series with one of the communication lines, and operates when a communication current flows through the detection resistor to control the short-circuit operation of the detection resistor, and to control the short-circuit operation. And a short-circuit operation control circuit for maintaining the holding by the voltage between the two lines.

Further, the present invention discharges the charge of a timer capacitor of a timer circuit for monitoring the duration of the output voltage when the output voltages of the first and second power supply circuits do not reach a specified value. And a circuit for preventing the timer capacitor from malfunctioning and enabling remote disconnection of the communication line.

[0008]

On the station side, a positive or negative control DC voltage of a certain value or more is applied to the communication line through a constant current circuit that supplies a control DC current of a certain value. When the terminal device is in the high impedance state, the first power supply circuit operates by the control DC voltage applied on the station side, and the communication line disconnection operation circuit performs a predetermined disconnection operation.

When the terminal device is in the low impedance state, a constant control DC current is applied to the communication line, and the second power supply circuit detects this current and outputs a predetermined voltage. With this output, the communication line separation operation circuit performs a predetermined separation operation. When the disconnecting relay operates, the contact disconnects the terminal device side and keeps the communication line in a loop state, so that various tests can be performed from the station side.

As described above, when a constant control DC current is applied to the communication line, the second power supply circuit detects this current and outputs a predetermined voltage. Is larger than the specified value, the voltage appearing at the terminal of the detecting resistor inserted in series with the communication line becomes larger than the specified value. In this state, the second power supply circuit short-circuits the detection resistor so as not to affect the communication current, and the short-circuit operation of the detection resistor is maintained by the communication line. This is performed by the line voltage.

When the first and second power supply circuits operate, when the duration of the output voltage is shorter than a specified value, or
When the voltage value is smaller than the specified value, the communication line disconnection operation circuit may not operate normally. In this case, the timer capacitor of the communication line disconnection operation circuit is switched to the short-circuit state, and the timer capacitor does not erroneously charge or malfunction.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit diagram of a communication line remote disconnecting apparatus according to an embodiment of the present invention. In FIG. 1, L1 and L2 are two-wire communication-side connection terminals, and T1 and T2 are terminal-side connection terminals. Reference numeral 1 denotes a first power supply circuit. This circuit 1 is used for controlling a terminal device connected to a communication line in a high impedance state when a disconnection operation is performed. It operates by a DC voltage and outputs an operating voltage Vcc of a communication line disconnecting operation circuit 6 described later. The diode 11 is for protection when the output of the first power supply circuit and the output of the second power supply circuit are connected in parallel. First
Components of the power supply circuit 1 include a Zener diode,
It comprises a non-linear voltage control element such as a transistor circuit.

Reference numeral 2 denotes a second power supply circuit, which comprises a current detection control circuit 3 and a short-circuit operation control circuit 4. The current detection control circuit 3 operates by a constant value control DC current supplied to the communication line when the terminal device performs a disconnection operation when the terminal device is connected to the communication line in a low impedance state. An operation voltage Vcc for the line segment operation circuit 6 is output.

Reference numeral 31 denotes a detection resistor, which is inserted in series between the terminals L2 and T2 and is used to detect a control direct current. Reference numeral 32 denotes a capacitor, which is connected in parallel to the resistor 31 and is used for AC current bypass. Reference numeral 33 denotes a Zener diode which is connected in parallel with the resistor 31 and is turned on when a terminal voltage generated at the resistor 31 is larger than a specified value, and is used for protecting the resistor 31 and related circuit components. is there. Reference numeral 34 denotes a low-resistance diode, which operates when the direction of the current flowing through the resistor 31 is reversed, and prevents the generation of an unnecessary voltage appearing at the terminal of the resistor 31. A resistor 35 is for adjusting the output current, and a diode 36 is for protecting when the output of the second power supply circuit 2 and the output of the first power supply circuit 1 are connected in parallel.

In the communication state, the short-circuit operation control circuit 4
It operates when the communication current is supplied to the resistor 31 and controls the short-circuit operation of the control DC current detection resistor 31. 41 is a field effect transistor (FET),
The ET 41 is for short-circuiting the resistor 31 when turned on. A Zener diode 42 is turned on when the terminal voltage of the resistor 31 is higher than a specified value. When a current due to this ON flows through the resistor 43, a voltage is generated across the resistor. The transistor 44 is turned on at this voltage. When the transistor 44 is turned on, an energizing circuit is formed from the terminal L1 side communication line via the resistors 45, 46, 91 and the diode 92, and the operation circuit of the FET 41 is set.

The transistor 47 is turned on by a terminal voltage generated by a current flowing through the resistor 46. When the transistor 47 is turned on, a current flows through the resistors 48 and 49, and the voltage turns on the FET 41 to short-circuit the resistor 31. When a current flows through the resistors 48 and 49, the transistor 40 is turned on. When the transistor 40 is turned on, there is no voltage across the resistor 31 shorted by the FET 41, and thus the operation of the FET 41 is maintained even when the transistor 44 is turned off.

Reference numeral 5 denotes a charge / discharge control circuit. This circuit 5 controls the communication line disconnection operation circuit 6 when the operation output voltage Vcc is lower than a specified value or when the duration of the voltage Vcc is shorter than a predetermined value. The timer capacitor 71 is short-circuited to control the discharge of the charged electric charge. Reference numeral 51 denotes a transistor. The collector and the emitter of the transistor 51 are connected in parallel to a timer capacitor 71. When Vcc is lower than a specified value, the transistor 51 is turned on.
1 is discharged.

Reference numeral 52 denotes a voltage detector.
When cc is lower than the specified value, the resistors 53 and 54 are energized, the transistor 51 is turned on, and the charge of the timer capacitor 71 is discharged. When Vcc is at the specified value, the resistors 53 and 54 are not energized.
1 remains off, and the timer capacitor 71 is charged. The resistor 55 is for discharging current in the circuit of the voltage detector 52 of the Vcc voltage, and the diode 56 is for preventing backflow.

Reference numeral 6 denotes a communication line disconnection operation circuit.
Comprises a timer circuit 7 and a disconnection relay control circuit 8.
When a predetermined voltage Vcc is applied, the timer circuit 7 operates the disconnection relay control circuit 8 after a predetermined time.
A predetermined time constant circuit is constituted by the timer capacitor 71 and the resistor 72. The comparator 73 is provided between the voltage defined by the reference voltage indicating resistors 74 and 75 and the timer capacitor 71.
And outputs when they match.

The disconnection relay control circuit 8 operates when the timer circuit 7 is charged to a predetermined voltage, operates the communication line disconnection relay operating winding 81-A, and disconnects the communication line. Do. The communication line disconnection relay has two wires, an operation winding 81-A and a recovery winding 81-B, and separates the communication line by operation, and ry1 and ry2 are their contacts. .

Further, since the separation relay is of a self-holding type, even if the recovery winding 81-B is not energized,
The operation is maintained, but is restored when a current in the opposite direction is applied to this winding. The capacitor 87, the resistor 88, and the diode 89 are all for stable operation of the communication line disconnecting relay.

The disconnecting relay operating capacitor 82 is connected to Vc
Then, the communication line disconnecting relay is operated with the charged electric charge. The FET 83 is an energizing element that discharges the charge of the capacitor 82 to the operating winding 81-A of the relay, and is controlled so as to trigger when the timer capacitor 71 is charged to a constant value. The FET 83 outputs the output of the comparator 73 to the diode 84, the resistor 85 and the capacitor 86.
Triggered by receiving the circuit.

Next, the operation of the above embodiment will be described. For convenience of explanation, the terminal L1 has a positive polarity at the time of the separating operation, and has a negative polarity at the time of restoration. When the terminal device side is in the high impedance state, the first power supply circuit 1 operates by the control DC voltage applied to the communication line, makes the disconnection operation circuit 6 operable and starts charging the timer capacitor 71. I do. When the timer capacitor 71 is charged to a predetermined voltage, the comparator 73 detects this, and
The FET 83 of the conducting element is triggered to conduct between the drain and the source. The charge of the capacitor 82 is discharged through the operating winding 81-A of the disconnecting relay, and the disconnecting relay operates to separate the communication line by the contacts ry1 and ry2.

When the terminal device is in the low impedance state,
The first power supply circuit 1 does not operate. However, since a constant control DC current flows through the communication line, the second power supply circuit 2 detects the current flowing through the resistor 31 and outputs a predetermined voltage V
Output cc. With this output voltage Vcc, the communication line disconnecting operation circuit 6 operates in the same manner as described above, and disconnects the communication line.

When the line is in the communication state, the communication current is selected to be larger than the control DC current, so that the terminal voltage of the resistor 31 becomes larger than the specified value. Therefore, the Zener diode 42 is turned on, and the transistor 44 operates by the voltage generated in the resistor 43 by the current. When the transistor 44 is turned on, an energizing circuit from the terminal L1 side communication line is formed via the resistors 45, 46, 91 and the diode 92. The transistor 47 is turned on by the voltage generated at the resistor 46. This allows the resistors 48, 4
9 flows, and the voltage generated at that time causes FE
T41 is turned on, and the detection resistor 31 is short-circuited.

On the other hand, when the detection resistor 31 is short-circuited,
Since the zener diode 42 is turned off, the transistor 44 is also turned off. However, since the transistor 40 continues to be on, the FET 41 continues to operate and the short-circuit state of the detection resistor 31 is continued. With the above operation, the detection resistor 31 continues the short-circuit state.
The effect of the insertion of 1 on communication will be eliminated.

[0027]

As described above, according to the present invention,
Since the detection resistor inserted into the communication line for detecting the control DC current is short-circuited during communication, it does not hinder communication. Further, since the holding circuit is configured to be maintained at the line voltage of the communication line, there is an effect that the holding circuit does not hinder communication.

Further, since a field effect transistor is used as the short-circuiting element, there is an advantage that the short-circuiting effect is greater than when other elements are used. Further, when the voltage corresponding to Vcc is lower than the specified value or disappears for a specified time or less, the charge of the timer capacitor is discharged in a short time. There is an advantage that it operates and does not malfunction.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a communication line cutting device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st power supply circuit 2 2nd power supply circuit 3 Current detection control circuit 31 Detection resistor 33,42 Zener diode 34,36 diode 4 Short circuit operation control circuit 41,83 FET 40,44,47,51 Transistor 5 charge Discharge control circuit 52 Voltage detector 6 Communication line disconnection operation circuit 7 Timer circuit 71 Timer capacitor 72 Time constant resistor 73 Voltage comparator 74, 75 Reference voltage display resistor 8 Disconnect relay control circuit 81-A Disconnect Winding for operating the relay 81-B Winding for restoring the disconnecting relay 82 Capacitor for operating the disconnecting relay ry1 ry2 Contact of the communication line disconnecting relay

Claims (2)

(57) [Claims] 1. A first power supply circuit connected between two-wire communication lines, operated by a control DC voltage of a certain value or more applied to the communication lines, and outputting a predetermined voltage; A second power supply circuit that outputs a predetermined voltage only when the control DC current is supplied to the communication line, and the output voltage of either one of the first or second power supply circuit is A timer circuit including a time constant circuit including a capacitor for a timer and a resistor for operating and monitoring the duration of the output voltage, and a separation relay control circuit for controlling a switching relay for separating a communication line. In the communication line remote disconnecting device that separates the communication line by the configured communication line disconnection operation circuit, the second power supply circuit is connected to one of the communication lines to detect the control DC current. With a detection resistor inserted in series It operates when a communication current flows through this detection resistor, controls the short-circuit operation of the detection resistor, and maintains the short-circuit operation with a voltage between both lines. Become a communication line remote disconnecting device. 2. The communication line remote disconnecting device according to claim 1, wherein when the output voltages of the first and second power supply circuits do not reach a specified value, a timer for monitoring the duration of the output voltage. A communication circuit for discharging a charge of a timer capacitor of the circuit, thereby preventing malfunction of the timer capacitor and enabling remote separation of a communication line.