JPH0583371A - Exchange system - Google Patents

Abstract

PURPOSE:To provide an exchange system which can interrupt a noise at the time of hooking on a telephone set with easy constitution. CONSTITUTION:In an exchange to have an interface means for connecting lines and a channel switch and perform the exchanging connection between mutual lines stored through the interface means for connecting the lines by the channel switch, interface means 3a and 4a for connecting a telephone set are provided as the interface means for connecting the lines, and a hook detecting means 23 to detect the hook condition of the telephone set connected to itself and an interrupting means 25 to circuit-interrupt voice signal transmission systems 9, 13 and 14 to deliver a voice signal at the section of a telephone set connected to itself when the hook detecting means 23 detects the on-hook are provided at the interface means for connecting the telephone set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching system for improving a speech path system in a time division speech path system used in a PCM time division exchange or the like.

[0002]

2. Description of the Related Art A PCM (Pulse Code Modulation) time division switch is generally a subscriber circuit which is an interface for connecting telephones and the like, a time division switch for connecting the subscriber circuits to each other, and a central office line. It is composed of an office line trunk circuit which is an interface for connecting to each other and a control circuit which controls these to realize a function as an exchange.

Then, this exchange digitizes a call signal (voice signal or the like) from a subscriber circuit or a call signal (voice signal or the like) from a trunk circuit and converts it into a PCM signal so as to correspond to a call partner. The time-division switch distributes the signal, converts it to an analog signal again, and then sends it to the other party's line so that it can be exchanged and used for communication.

That is, in the digital exchange, since the exchange operation by the time division switch is performed by using the time slot determined with the other party to be connected, the call signal (in the time slot corresponding to the subscriber circuit or trunk circuit of the other party) A voice call can be made by inserting and removing (such as a voice signal).

FIG. 3 shows an example of an exchange system using a conventional PCM time division exchange. In the figure, 10 is a PC
M time division exchanges, 1 and 2 are telephones accommodated in the PCM time division exchange 10, and 3 and 4 are subscriber circuits provided in the PCM time division exchange 10. The subscriber circuits 3 and 4 convert a voice (analog) signal from the telephone into a PCM signal, and at the same time, convert a PCM signal sent through the time division switch 5 into a voice (analog).
It has a function of converting into a signal.

The time division switch 5 connects a plurality of subscriber circuits to form a PCM communication path. A trunk circuit 6 functions as an interface between the office line and the time division switch 5. Reference numeral 7 denotes a station line connection terminal, and the station line is connected to the station line trunk circuit 6 via the station line connection terminal 7. A control circuit 8 controls the operations of the subscriber circuits 3 and 4, the time division switch 5 and the office line trunk circuit 6. On the other hand, FIG. 4 shows a simplified configuration of the subscriber circuits 3 and 4.

In the figure, reference numeral 9 is a hybrid transformer, and this hybrid transformer 9 performs two-line / four-line conversion of a communication path. One winding of the hybrid transformer 9 is divided into two windings L1 and L2 to form a 2-wire side winding, and the other winding serves as a 4-wire side winding L3.

One end of the 4-wire conversion side winding L3 is grounded through the matching load circuit 11a, and the other end is connected through the matching load circuit 11b and the low-pass filter 14 to the digital / analog of the CODEC. (D / A)
It is connected to the converter 16. An intermediate tap TP is provided on the 4-wire side winding L3 of the hybrid transformer 9, and the intermediate tap TP is grounded via the matching load circuit 11c.

Reference numeral 13 is a low-pass filter, and the one end side of the 4-wire conversion side winding L3 of the hybrid transformer 9 is connected via the low-pass filter 13 to the codec (C
ODEC) analog / digital (A / D) converter 1
Connected to 5. The low pass filters 13 and 14 are for removing high frequency components of the audio signal.

The A / D converter 15 is for converting a voice (analog) signal into a PCM signal and sending it to the time division switch 5, and the D / A converter 16 is for the time division switch 5.
It is for converting the PCM signal sent from the device into a voice (analog) signal and sending it to the hybrid transformer 9 side.

Reference numerals 17 and 18 are telephone connection terminals, and
Reference numerals 9 and 20 are connection terminals for time divisional switches. One end of the winding L1 on the two-wire conversion side of the hybrid transformer 9 is connected to the telephone connection terminal 17, and the telephone connection terminal 18 is connected.
Is the winding L2 on the 2-wire conversion side of the hybrid transformer 9.
Of the A / D converter 15 is connected to the time-division switch connection terminal 19, and the input side of the D / A converter 16 is connected to the time-division switch connection terminal 20.

Further, 21 is a constant voltage source, 22 is a letter coil, and the other ends of the windings L1 and L2 of the hybrid transformer 9 are connected to the constant voltage source 21 and the letter coil 22, respectively. Electric power is supplied to the telephones 1 and 2 by the voltage source 21 and the letter coil 22.

In the conventional apparatus having such a structure, the concept of the conventional PCM time division switch will be described first. Now, suppose that one subscriber takes the telephone 1 off hook to make a call. Then, a signal indicating that the telephone 1 is off-hook is sent from the subscriber circuit 3 to which the telephone 1 is connected to the control circuit 8. When the control circuit 8 receives the off-hook signal, it sends a command to the time division switch 5 to connect the time division switch 5 to the subscriber circuit 3.

When the operator of the telephone 1 dials the telephone number assigned to the telephone 2, the dial signal is sent to the control circuit 8, and the control circuit 8 receiving the dial signal recognizes the telephone number from the dial signal. Then, the calling signal is sent to the corresponding subscriber circuit 4.

The call signal causes the telephone 2 to ring to notify of the incoming call. Then, when the telephone 2 responds (off-hook) by this, the control circuit 8 sends a command to the time division switch 5 to connect the subscriber circuit 3 and the subscriber circuit 4 via the time division switch 5, Secure.

In this way, when the PCM communication path is formed between the subscriber circuit 3 and the subscriber circuit 4, the telephone 1
The audio signal from the signal reaches the low pass filter 13 through the hybrid transformer 9 of the subscriber circuit 3, and the low pass filter 13 removes high frequency components from the signal. The audio signal from which high frequency components have been removed is further A / D
It is sent to the converter 15, where it is converted into a PCM signal and sent to the time divisional switch 5 via the terminal 19. The time division switch 5 sends the PCM signal to the subscriber circuit 4 via the PCM communication path.

The PCM signal sent to the subscriber circuit 4 reaches the D / A converter 16 via the terminal 20, where the PCM signal is reconverted into an analog signal, which is opposite to the A / D conversion. Furthermore, the analog signal is a low-pass filter 14
The waveform is shaped by and is output from the telephone 2 as a voice signal through the hybrid transformer 9. Phone 2
The voice signal of the subscriber using is also output from the telephone 1 through the same process, and the mutual call between the telephone 1 and the telephone 2 becomes possible.

When the telephone set 1 or the telephone set 2 goes on hook, a signal indicating that the telephone set has gone on hook goes to the subscriber circuit 3.
Alternatively, it is sent from the subscriber circuit 4 to the control circuit 8. As a result, the control circuit 8 sends a command to the time divisional switch 5, and the time divisional switch 5 disconnects the communication path formed between the subscriber circuit 3 and the subscriber circuit 4. Now, consider a case where a communication path is formed between the telephone 1 and the telephone 2 and one of the telephones goes on-hook after the telephone call.

FIGS. 5 and 6 are diagrams of the conventional example shown in FIGS. 3 and 4 when attention is paid to the hook signal. In FIG. 6, 23 is a hook-on / hook-off detection circuit for detecting hook-on / hook-off of a telephone connected to the subscriber circuit, and 24 is this hook-on / hook-off detection circuit. The detection signal (hook signal) at 23 is supplied to the control circuit 8 of the PCM time division exchange 10.
It is an output terminal for outputting to.

Now, it is assumed that a communication path is formed between the telephone 1 and the telephone 2. When the telephone set 1 goes on-hook, the hook detection circuit 23 of the subscriber circuit 3 detects that the telephone set is on-hook, and P via the terminal 24.
An on-hook signal is sent to the control circuit 8 of the CM time division exchange 10. When the control circuit 8 receives this on-hook signal, it determines that the telephone 1 has terminated the call, and sends a control signal to the time division switch 5 in the PCM time division exchange 10 so that the subscriber circuit 3 and the subscriber circuit 4 are connected. Disconnect the communication path between them.

By receiving the on-hook signal in this way, the call-end processing is started and the communication path is disconnected. Even if the telephone 1 is on-hook, the operating speed of the control circuit 8 causes the telephone 1 to be disconnected. Since the communication path between the telephone and the telephone 2 is not immediately disconnected, the communication path is maintained for a while after the on-hook. As described above, in the conventional method, after the telephone call ends (on-hook), the communication path is maintained for a while.

[0022]

As described above, in the conventional method, when a telephone call is made between telephones connected to the exchange,
Two telephones exchange voice signals via the call route secured by the call route switch to enable a telephone call, but one of the telephones in the call state goes on-hook to control the exchange. The circuit determines that the call has ended, and controls the call path switch. The call path switch disconnects the call paths of both telephones in the call and ends the call termination process. However, due to the operating speed of the control circuit of the exchange, it will take some time from the on-hook state of one of the telephones in the call state to the completion of the call path disconnection process between the telephones in the call state. During this time, the communication path remains formed. Therefore, the following problems remain.

First, when one of the telephones is on-hook, the terminals 17 and 18 to which the telephone is connected are connected.
Since the impedance between them (impedance on the 2-wire side of the hybrid transformer 9 which is a 2-wire / 4-wire conversion circuit) becomes high, the 2-wire side of the hybrid transformer 9 easily picks up external noise, power source noise, and the like. Since the communication path is still maintained, the noise induced on the 2-wire side of the hybrid transformer 9 may be output as noise to the other telephone via the 4-wire side.

When one of the telephones is on-hook, the side tone of the other party's telephone increases due to the mismatch of the two-wire / four-wire conversion circuit, and when the conditions are bad, the other party's telephone emits a ringing sound. There was a risk of this occurring.

Further, in the conventional method, the process of "hook detection → confirm hook detection signal → time division switch control" takes time, and the data processing speed of the control circuit 8 is limited. It was not possible to quickly follow the on / off operation of.

Of course, if the control circuit is composed of a high-speed CPU or the like, quick follow-up is possible to some extent, but for that reason, the circuit becomes extremely expensive, and the cost of the system is greatly increased. Therefore,
The object of the present invention is to provide a hook with a simple structure.
An object is to provide an exchange system capable of cutting off noise when turned on.

[0027]

In order to achieve the above object, the present invention is configured as follows. That is, in a switch having a line connection interface means and a call path switch, and performing a switch connection between the lines accommodated through the line connection interface means by the call path switch, the line connection interface A telephone connection interface means is provided as a means, and the telephone connection interface means includes hook detection means for detecting a hook state of a telephone connected to itself.
When the hook detecting means detects an on-hook condition, a disconnecting means for disconnecting the circuit of the audio signal transmission system for exchanging the audio signal with the telephone connected to itself is provided.

[0028]

In the above structure, the telephone connection interface means provided as the line connection interface means has the hook detection means for detecting the hook state of the telephone connected to itself, and the telephone connected to itself. The interruption means for controlling the interruption of the circuit of the audio signal transmission system for exchanging the audio signal with and off interrupts the circuit of the audio signal transmission system when the hook detection means detects on-hook.

For this reason, when one of the telephones in a call state is hooked on, the call path is temporarily maintained and is generated due to the impedance of the voice circuit. Noise transmission to the other telephone,
The audio signal transmission system can be cut off by the circuit cutoff, and can be realized with a simple configuration without changing other components.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit configuration diagram of a subscriber circuit showing an embodiment of the present invention, and FIG. 2 is a configuration diagram of an exchange system using the subscriber circuit.

In FIG. 2, reference numeral 10 is a PCM time division exchange, and 1 and 2 are telephones accommodated in the PCM time division exchange 10. Further, 3a and 4a are subscriber circuits provided in the PCM time division exchange 10, and the telephones 1 and 2 are connected to the subscriber circuits 3a and 4a and accommodated in the PCM time division exchange 10.

The subscriber circuits 3a and 4a convert a voice (analog) signal from the telephone into a PCM signal and, at the same time, send the PC through the time division switch 5.
It has a function of converting an M signal into a voice (analog) signal.

The time division switch 5 connects a plurality of subscriber circuits to form a PCM communication path. A trunk circuit 6 functions as an interface between the office line and the time division switch 5. Reference numeral 7 denotes a station line connection terminal, and the station line is connected to the station line trunk circuit 6 via the station line connection terminal 7. 8 is a control circuit, which is a subscriber circuit 3a, 4a,
The operation of the time division switch 5 and the office line trunk circuit 6 is controlled.

FIG. 1 shows a simplified structure of the subscriber circuits 3a and 4a. In the figure, 9 is a hybrid transformer, and the hybrid transformer 9 is a two-line / four-line system for a communication path. It's converting. hybrid·
One winding of the transformer 9 is divided into two windings L1 and L2 to form a two-wire side winding, and the other winding serves as a four-wire side winding L3. One end of the 4-wire conversion side winding L3 is grounded through the matching load circuit 11a, and the other end is connected through the matching load circuit 11b and the low-pass filter 14 to the digital / analog (D / D) of the codec (CODEC). A) It is connected to the converter 16. An intermediate tap TP is provided on the 4-wire side winding L3 of the hybrid transformer 9, and the intermediate tap TP is grounded via the matching load circuit 11c.

Reference numeral 13 denotes a low-pass filter, and the one end side of the 4-wire conversion side winding L3 of the hybrid transformer 9 is connected to the codec (C
ODEC) analog / digital (A / D) converter 1
Connected to 5. The low pass filters 13 and 14 are for removing high frequency components of the audio signal.

The A / D converter 15 is for converting a voice (analog) signal into a PCM signal and sending it to the time division switch 5, and the D / A converter 16 is for the time division switch 5.
It is for converting the PCM signal sent from the device into a voice (analog) signal and sending it to the hybrid transformer 9 side.

Reference numerals 17 and 18 are telephone connection terminals, and
Reference numerals 9 and 20 are connection terminals for time divisional switches. One end side of the winding L1 on the four-wire conversion side of the hybrid transformer 9 is connected to the telephone connection terminal 17, and the telephone connection terminal 18 is also connected.
Is the winding L2 on the 4-wire conversion side of the hybrid transformer 9.
Of the A / D converter 15 is connected to the time-division switch connection terminal 19, and the input side of the D / A converter 16 is connected to the time-division switch connection terminal 20.

Reference numeral 21 is a constant voltage source, 22 is a letter coil, and the other ends of the windings L1 and L2 of the hybrid transformer 9 are connected to the constant voltage source 21 and the letter coil 22, respectively. Electric power is supplied to the telephones 1 and 2 by the voltage source 21 and the letter coil 22. Reference numeral 23 is a hook-on / hook-off detection circuit for detecting hook-on / hook-off of a telephone connected to the subscriber circuit 30. Reference numeral 24 is the hook-on / hook-off detection circuit 23. It is an output terminal for outputting the detection signal (hook signal) in (1) to the control circuit 8 of the PCM time division exchange 10.

The above construction is the same as the conventional circuit shown in FIGS. 3 and 6. In the present invention, this conventional circuit is further provided with a switch 25 which can be turned on / off by a signal. That is, in the present invention, the switch 25 is provided between the low-pass filter 13 and one end of the four-wire side winding L3 of the hybrid transformer 9,
Moreover, the switch 25 is different from the conventional one in that it is opened and closed by a signal from the hook detection circuit 23.

With such a structure, the subscriber circuit 3a and the subscriber circuit 4a in the exchange system of FIG.
The subscriber circuit having the configuration shown in FIG. 1 is used as a telephone set 1 via the subscriber circuit 3a and the subscriber circuit 4a.
Consider the communication process between the and the telephone 2.

When both the telephone set 1 and the telephone set 2 are in the on-hook state, the switches 25 of the subscriber circuit of FIG. 1 used as the subscriber circuit 3a and the subscriber circuit 4a of FIG. 2 are off. Is set to. When phone 1 goes off hook, phone 2 goes off
The hook detection circuit 23 in the subscriber circuit 4a shown in FIG.
A hook signal indicating a hook is sent to the control circuit 8 via the output terminal 24.

At the same time, the hook signal causes the switch 25 to be closed, and the voice signal transmission line (call line) which is telephone set → hybrid transformer 9 → low pass filter 13 → A / D converter 15 → time division switch 5 ) Is formed.

Next, when the telephone number assigned to the telephone 2 is dialed in the telephone 1, the data of the telephone number is sent to the control circuit 8 in the PCM time division exchange 10 through the subscriber circuit 3a, and the control circuit 8 is sent. Calls the subscriber circuit 4a.

As a result, the telephone 2 rings the bell,
Notify you of an incoming call. As a result, when the user of the telephone set 2 who knows the incoming call goes off hook, a hook signal notifying the off hook is output from the detection circuit 23 of the subscriber circuit 4a and sent to the control circuit 8 to notify the response.

When the telephone 2 responds in this way, the control circuit 8 causes the time division switch 5 in the PCM time division exchange 10 to operate.
To connect the subscriber circuit 3a and the subscriber circuit 4a.

In this way, after the telephone path is formed between the telephone 1 and the telephone 2, when the telephone 1 is turned on and off, the hook detection circuit 23 of the subscriber circuit 3a turns on and off.
A hook signal indicating a hook is transmitted and given to the switch 25 of the subscriber circuit 3a. Immediately after receiving this, the switch 25 of the subscriber circuit 3a is opened, the one end side of the four-wire side winding L3 of the hybrid transformer 9 and the low-pass filter 13 are cut off, and the communication path is cut off. .. In this case, since the communication path itself is disconnected almost at the same time as the on-hook, there is no problem that the telephone hears noise or the side tone becomes loud.

On the other hand, in the telephone 1, even if chattering occurs during on-hook, the switch 25 responds quickly and disconnects the communication path, so that it can sufficiently cope with a sudden change such as chattering. ..

As described above, the subscriber circuit used in the present system is provided with a switch for physically disconnecting the call path by the on-hook of the connected telephone in the call path of the subscriber circuit. Since the call path is automatically cut off by on-hook, it is possible to disconnect the call path at the same time as the on-hook of the telephone during the call, without any modification to the control circuit of the exchange. Due to the delay of the call path disconnection process when on-hook as in the past,
It is possible to prevent noise from being generated in the other party's telephone and increase in sidetones due to the fact that the call path is maintained.

In short, in this system, the switch 25 is provided between the low-pass filter 13 and the four-wire side of the hybrid transformer 9 forming the voice signal transmission system (communication path) in the subscriber circuit. Is opened and closed by a signal from the hook detection circuit 23 for detecting the hook state of the telephone connected to the subscriber circuit. Therefore, the call path of the subscriber circuit is almost simultaneously with the on-hook of the telephone. Since the call is disconnected, it is possible to prevent the other party's phone from generating noise and increasing sidetone.

Further, since it can be realized by providing a switch for physically interrupting the communication path in the circuit of the voice signal transmission system, the control circuit of the exchange can be operated at high speed, and the load processing program of the control circuit can be executed. Without changing it, it can respond to chattering during on-hook and turn on / off the communication path.

The present invention is not limited to the embodiments described above and shown in the drawings, but can be appropriately modified and carried out within the scope not changing the gist of the invention. 25 is interposed between the low-pass filter 13 and the winding on the 4-wire side in the hybrid transformer 9 for 2-wire / 4-wire conversion, the winding on the 4-wire side and the low-pass filter in the hybrid transformer 9 are arranged. 14 may be provided between the low-pass filter 13 and the winding on the 4-wire side in the hybrid transformer 9, and the low-pass filter 13 and the winding on the 4-wire side in the hybrid transformer 9, respectively. It may be allowed to.

As described above in detail, this system has the interface means for line connection and the communication path switch,
In a switching system for performing exchange connection between lines accommodated via the line connection interface unit by a speech path switch, a telephone connection interface unit is provided as the line connection interface unit,
The interface means for connecting the telephone transmits a voice signal between the hook detecting means for detecting the hook state of the telephone connected to itself and the telephone connected to itself when the hook detecting means detects on-hook. The audio signal transmission system to be delivered and received is provided with an interruption means for interrupting the circuit.

In such a structure, the telephone connection interface means provided as the line connection interface means has hook detection means for detecting the hook state of the telephone connected to itself, and the hook detection means is connected to itself. The disconnecting means for controlling the circuit disconnection of the audio signal transmission system for exchanging the audio signal with the telephone set is designed to disconnect the circuit of the audio signal transmission system when the hook detecting means detects the on-hook. Is.

For this reason, when one of the telephones in a call is hooked on, the call path is temporarily maintained and is generated due to the impedance of the voice circuit. Noise transmission to the other telephone,
It can be cut off by cutting off the circuit of the audio signal transmission system,
Moreover, it can be realized with a simple configuration without changing other components.

[0055]

As described above in detail, according to the present invention, the telephone line can be disconnected at the same time as the on-hook operation of the telephone set during the call, which causes noise on the other side telephone set and increases the side tone. Besides, it can be realized by installing a switch that physically cuts off the communication path in the circuit of the voice signal transmission system, so that the control circuit of the exchange can be operated at high speed and the load processing program of the control circuit can be implemented. It is possible to provide a switching system that can respond to chattering during on-hook and turn on / off the communication path without changing.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing details of essential parts of the present invention.

FIG. 2 is a system block diagram of an exchange system to which the present invention is applied.

FIG. 3 is a schematic configuration diagram showing an example of a conventional PCM time division exchange.

FIG. 4 is a schematic diagram of an example of a conventional subscriber circuit.

FIG. 5 is a diagram showing a hook signal and a control signal system in an example of a conventional PCM time division switch.

FIG. 6 is a diagram showing a hook detection signal system in a conventional subscriber circuit.

[Explanation of symbols]

3a, 4a ... Subscriber circuit, 9 ... Hybrid transformer, 11a-11c ... Matching load circuit, 13, 14 ... Low-pass filter, 15 ... Analog / digital (A /
D) converter, 16 ... Digital / analog (D / A) converter, 23 ... Hook-on / hook-off detection circuit, 25 ...
switch.

Claims (1)

[Claims] 1. A switching system comprising a line connection interface means and a call path switch, wherein a call path switch is used to perform exchange connection between lines accommodated through the line connection interface means. An interface means for connecting a telephone is provided as an interface means for connecting the telephone, and the interface means for connecting the telephone includes a hook detecting means for detecting a hook state of a telephone connected to itself, and an on-hook state by the hook detecting means. An exchange system comprising: a disconnection means for disconnecting a voice signal transmission system for transmitting and receiving a voice signal to and from a telephone connected to the self when detected.