JPH01137792A - Subscriber circuit for telephone exchange - Google Patents

Abstract

PURPOSE:To quickly inform the occurrence of overcurrent to a host controller by providing an overcurrent detection circuit detecting the overcurrent of call current and an overcurrent detection display circuit consisting of an AND circuit. CONSTITUTION:The overcurrent detection circuit 6 compares the voltage of the A line 2 of a subscriber's line with prescribed voltage, detects the overcurrent of the call current and outputs a prescribed detection signal when a normal signal NOR is inputted. Besides, when a reverse signal REV is inputted, it compares the voltage of the B line 3 of the subscriber's line with a prescribed voltage, detects the overcurrent of the call current and outputs a prescribed detection signal. Then the overcurrent detection display circuit 7 takes the AND of an SCN signal from a power supplying circuit and the prescribed detection signal from the circuit 6 and outputs an overcurrent detection signal OIL to the host controller when the AND exists. In that way, the occurrence of the overcurrent can be quickly informed to the host controller.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a subscriber circuit of a telephone exchange, and in particular compares the voltage of the A line or the B line of the subscriber line with a predetermined voltage to determine the communication current. The present invention relates to a subscriber circuit that detects an overcurrent and outputs a predetermined signal to notify a host control device of the detection of the overcurrent.

[Conventional technology]

Conventionally, in the subscriber circuit of a telephone exchange, an overcurrent protection circuit is provided in the power supply circuit that applies a predetermined voltage between the A line and the B line of the subscriber line, and when the communication current becomes an overcurrent, In this case, this protection circuit operated to prevent damage to the subscriber circuit.

[Problem that the invention seeks to solve]

However, in such conventional subscriber circuits, although the protection circuit operates when the communication current becomes an overcurrent, it is not configured to notify the higher-level control device of the occurrence of the overcurrent.

As a result, the higher-level control device cannot detect the overcurrent of the call current, and as a result, the overcurrent protection circuit operates all the time, which impedes the normal operation of the subscriber circuit, and furthermore, the overcurrent may continue for a long time. There was a risk that the subscriber circuit would be destroyed.

SUMMARY OF THE INVENTION An object of the present invention is to solve such problems and provide a subscriber circuit for a telephone exchange that can detect an overcurrent in a telephone call current and send a predetermined signal to immediately notify a higher-level control device of the occurrence of an overcurrent. It's about doing.

[Means for solving problems]

The present invention is connected to a subscriber terminal by A line and B line of a two-wire subscriber line, applies a voltage to the A line and the B line, and connects a loop between the A line and the B line. In a subscriber circuit of a telephone exchange equipped with a power supply circuit that monitors the state, an overcurrent detection circuit that detects an overcurrent in the communication current by comparing the voltage of the A line or the voltage of the B line with a predetermined voltage; , a logical product is performed between the output of the power supply circuit indicating that the subscriber line is in a loop state and the overcurrent detection output of the overcurrent detection circuit, and when the logical product is established, a predetermined overcurrent detection signal is generated. The present invention is characterized in that it is equipped with an AND circuit that outputs .

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing this embodiment. This subscriber circuit includes a switch circuit 4, a power supply circuit 5, an overcurrent detection circuit 6, and an overcurrent detection display circuit 7.

One end of the switch circuit 4 is connected to the subscriber terminal 1 by A line 2 and B line 3 of the two-wire subscriber line, and the other end is connected to the power supply circuit 5.
It is connected to the. The switch circuit 4 switches the polarity of the voltage applied to the subscriber line.

The power supply circuit 5 is equipped with ground air through a constant resistance and a battery through a constant resistance, and supplies communication current to the subscriber terminal 1, and connects the subscriber line A line 2 and B line 3 with each other. The loop state of the subscriber line is monitored, and when the subscriber line is in a loop state, an SCN signal is output to notify the higher-level control device.

The overcurrent detection circuit 6 is connected to the A line 2 and B line 3 of the subscriber line, and compares the voltage of the A line 2 with a predetermined voltage, or the voltage of the B line 3 with a predetermined voltage, and determines the communication current. Detects overcurrent. When overcurrent is detected, a predetermined detection signal is output.

The overcurrent detection display circuit 7 calculates the AND of the SCN signal from the power supply circuit 5 and the predetermined detection signal from the overcurrent detection circuit 6, and when the AND is established, outputs a predetermined overcurrent detection signal OIL. Output to the upper control device.

Next, the operation will be explained. The switch circuit 4 connects the subscriber terminal 1
is on-hook and in the call monitoring state, connect the V0 volt battery from the power supply circuit 5 through a constant resistance to the A line 2,
On the other hand, the B line 3 is supplied with earth air through a constant resistance of the same value.

When the subscriber terminal 1 is off-hook and is in a talking state, the switch circuit 4 receives the normal signal NOR and supplies a Vl1m volt battery to the A line 2 through a constant resistance and a ground voltage to the B line 3 through a constant resistance. The communication current is supplied to the subscriber terminal 1 in a normal power supply state where the terminal 1 is in a normal power supply state, or in a reverse power supply state with a reverse polarity in which a reverse signal REV is input.

During a call, in the normal power supply state, the voltage of the A line 2 of the subscriber line is within the range of Vmm/2 to V1m volts, and in the reverse power supply state, the voltage of the B line 3 of the subscriber line
The voltage of is in the range of V■/2 to VlB volts. When a current exceeding the permissible value flows as a communication current, the voltage of the A line 2 of the subscriber line will be approximately Vs in the normal power supply state.
w/2 volts or more, and in the reverse power supply state, the voltage of the B line of the subscriber line becomes approximately Vgs/2 volts or more.

When the normal signal NOR is input (normal power supply state), the overcurrent detection circuit 6 compares the voltage of the A line 2 of the subscriber line with a predetermined voltage to detect an overcurrent of the communication current. Outputs a predetermined detection signal. Also, when the reversal signal REV is input (reversal power supply B),
The voltage of line B of the subscriber line is compared with a predetermined voltage to detect an overcurrent in the communication current, and the predetermined detection signal is output.

Then, the overcurrent detection display circuit 7 performs a logical product of the output signal of the overcurrent detection circuit 6 and the output signal of the power supply circuit 5, and the predetermined detection signal and the SCN signal are outputted from each circuit, and the logical product is calculated. When established, the overcurrent detection signal OIL is output to the host control device. In other words, when the subscriber line is in a loop state and an overcurrent of the communication current is detected,
An overcurrent detection signal OIL is sent, and an overcurrent display of the communication current is performed to the host control device.

〔Effect of the invention〕

As explained above, the present invention connects the A line and B line of a two-wire subscriber line to a subscriber terminal, applies voltage to the A line and B line, and connects the A line and B line. In the subscriber circuit of a telephone exchange equipped with a power supply circuit that monitors the loop state between , the output of the power supply circuit indicating that the subscriber line is in a loop state, and the overcurrent detection output of the overcurrent detection circuit, and
and an AND circuit that outputs a predetermined overcurrent detection signal when the AND is established.

Therefore, according to the present invention, it is possible to realize a subscriber circuit of a telephone exchange that can detect an overcurrent in a telephone call current, send a predetermined signal, and immediately notify a host controller of the occurrence of an overcurrent. As a result, it is possible to solve the problem that the normal operation of the subscriber circuit is inhibited or that an overcurrent of the communication current occurs for a long time and the subscriber circuit is destroyed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. 2...A line 3...B line 4...Switch circuit 5...Power supply circuit 6...Overcurrent detection circuit 7...Overcurrent detection display circuit

Claims (1)

[Claims] (1) Connected to the subscriber terminal by the A line and B line of a two-wire subscriber line, applying voltage to the A line and the B line, and looping between the A line and the B line. In a subscriber circuit of a telephone exchange equipped with a power supply circuit that monitors a power supply circuit, an overcurrent detection circuit detects an overcurrent in a communication current by comparing the voltage of the A line or the voltage of the B line with a predetermined voltage; The output of the power feeding circuit indicating that the subscriber line is in a loop state is ANDed with the overcurrent detection output of the overcurrent detection circuit, and when the AND is established, a predetermined overcurrent detection signal is generated. A subscriber circuit for a telephone exchange, comprising an AND circuit that outputs an output.