JPS5823037B2 - Kokan Cairo - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to switching circuits used in telephone exchanges, data exchanges, and the like.

In the above-mentioned switching equipment, crosstalk generated from the switching circuit adversely affects the performance of the switching equipment, and various methods have been proposed to reduce this crosstalk.

There are various types of crosstalk, but there is crosstalk that occurs from one line during a call to another line that is not in use through a switching element such as a relay or electronic contact.

This crosstalk component further acts as crosstalk on other lines in use, causing interference as intelligible calls, or acts as noise as unintelligible crosstalk.

When the crosstalk component is small, such interference is small, but as the scale of the exchange increases, the crosstalk component also accumulates and becomes a large disturbance.

Unused lines that cause such interference include lines that are incoming to the switching circuit and are unused if they are not connected to subscribers for backup purposes due to maintenance or other reasons, and lines that are outgoing from the switching circuit due to traffic volume and Some circuits are removed from the trunk circuit for reasons such as economic efficiency.

Crosstalk components generated via these fixed unused lines can be reduced by grounding at least one of the fixed unused incoming lines or outgoing lines with a sufficiently low impedance value in the required frequency band of the signal to be exchanged. has been proposed using a crosstalk reduction method described in Japanese Patent Application No. 78936/1983.

However, in normal cases, from the viewpoint of the usage efficiency and economic efficiency of switching equipment, the proportion of fixed vacant incoming and outgoing lines is small compared to the total number of incoming and outgoing lines of the switching circuit, and even if these are grounded, However, it is not possible to expect a significant reduction in the amount of crosstalk.

In other words, a major cause of crosstalk is the contact capacity and wiring capacity associated with incoming and outgoing lines that are not in use even when subscribers, links, trunks, etc. are physically connected to the switching circuit. .

An object of the present invention is to reduce crosstalk due to contact capacitance and wiring capacitance associated with such unused incoming and outgoing wires.

The switching circuit of the present invention includes an incoming line group connected to a subscriber, an outgoing line group that intersects the incoming line group, and, if necessary, interaction between required incoming lines and outgoing lines of these incoming line groups and outgoing line groups. In order to make a connection, a plurality of switching elements are provided at any intersection of these incoming lines and outgoing lines, and the switching elements connected to at least one of each incoming line or each outgoing line are connected to each other and the switching element is connected to at least one of each incoming line or each outgoing line and changes in current or voltage. a plurality of conduction state detection circuits that detect the conduction state of and a plurality of short circuits that ground at least one of the wires.

The switching circuit of the present invention also includes an incoming line group connected to a subscriber, an outgoing line group that intersects with the incoming line group, and required incoming and outgoing lines of these incoming line group and outgoing line group as necessary. In order to perform interconnection between the subscriber and the input line, a plurality of switching elements are provided at arbitrary intersections among the intersections of the input line and the output line, and a plurality of switching elements are connected to each of the input lines and connect the subscriber and the input line. a plurality of direct current isolation circuits for preventing direct current from flowing between them; and a plurality of receiver disconnection detection circuits for detecting when a subscriber connected through these direct current isolation circuits disconnects from the handset;
It is comprised of a plurality of short circuits that ground the input line with a sufficiently low impedance value in the frequency band of the signal to be exchanged when the handset is not removed by the output of the detection circuit.

Furthermore, the switching circuit of the present invention includes an incoming line group connected to a subscriber, an outgoing line group that intersects with the incoming line group, and required incoming and outgoing lines of these incoming line group and outgoing line group as necessary. A plurality of switching elements are provided at any of the intersections of these incoming lines and outgoing lines to perform interconnection of the incoming lines, and a plurality of switching elements are connected to each of the incoming line groups and the switching elements are connected to each other by changes in current or voltage. a plurality of continuity state detection circuits for detecting a continuity state; a plurality of DC isolation circuits connected to each of the input lines and for preventing direct current from flowing between the subscriber and the input lines; A plurality of handset disconnection detection circuits connected through these DC isolation circuits detect when the subscriber disconnects the handset, and an output of the continuity state detection circuit and an output of the handset disconnection detection circuit detect whether the handset is disconnected. a plurality of determination circuits that determine whether the telephone is not in use or each incoming line is not in use, and the frequency band of the signal to be exchanged when the handset is not removed or each incoming line is not in use according to the output of the determination circuit; and a plurality of short circuits that ground the input line with a sufficiently low impedance value.

Here, the sufficiently low impedance is an impedance of several ohms or less, which is considered to be a sufficiently low impedance compared to the impedance of the switching circuit, for example, 600 ohms in a normal telephone exchange.

Therefore, even if it is not directly grounded, it is sufficient as long as the impedance is sufficiently low in the frequency band handled by the exchange circuit. I can't help it.

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment of the present invention.

In FIG. 1, incoming lines 101, 102, 103 and 104 connected to the ring (or subscriber) are connected to continuity state detection circuits 131, 132, 133 and 133, respectively, which detect the usage status of each incoming line by changes in voltage or current. 13
4 to the switching circuit 109.

Similarly, outgoing terminals 105, 106, 107 and 108 connected to the link (or trunk) are connected to switching circuit 109 via conduction state detection circuits 135, 136, 137 and 138, respectively.

Each incoming and outgoing line is interconnected by a switching circuit 109 as required.

Electronic circuit 121゜122.123,124,125,1
26, 127 and 128 are relay contacts 111, 112, 113 for grounding the input line or output line, respectively.
゜114.It has a relay winding for driving 115, 116, 117 and 118, and receives an output from each of the detection circuits 131-138 when the input or output wires are not used, and operates the relay contacts 111-118. drive

This causes the corresponding incoming wire to be grounded. Crosstalk components caused by contact capacitance and wiring capacitance associated with incoming or outgoing wires that are not in use are reduced.

FIG. 2 is a diagram showing an example of a circuit that detects a voltage change in the incoming line 101 (or outgoing line 105) in FIG. 1 and performs grounding accordingly.
) is used a field effect transistor (hereinafter referred to as FET).

The potential of the input line 201 corresponding to the input line 101 in FIG.
It is constantly applied to the gate of T205, and the input line 2
01 is used, the drain of FET 205 is maintained at approximately power supply voltage E.

As a result, the relay drive circuit 204 (electronic circuit 1 in FIG.
No current flows through the relay winding (corresponding to 21),
Contact 203 is in an open state.

When the input line 201 becomes unused, the gate voltage of the FET 205 changes, and the source and drain become conductive.

As a result, current flows through the relay winding of relay drive circuit 204, relay contact 203 closes, and unused wire 201 is grounded.

Here, the capacitor 202 is used to prevent a short circuit with the ground potential of the power supply.

The capacitance of this capacitor is preferably as large as possible in order to lower the impedance value, but in reality, it is selected from several μF to several + μF in consideration of economic efficiency, space factor, and the like.

FIG. 3 is a diagram showing a second embodiment of the present invention.

When an electronic contact such as a transistor or a diode is used as the switching element of the switching circuit 109 in FIG. 1, the switching circuit 309 as shown in FIG. each incoming line 301, 302, 303 and 304 and each subscriber 3
Subscriber circuits 361, 342, 343 and 344 are inserted between the subscriber circuits 361, 342, 343 and 344, and these circuits supply power to the subscribers 341 to 344 and connect each incoming line 301 to 304 and each subscriber 341 DC insulation etc. are performed to prevent direct current from flowing between the terminals 344 and 344.

In such a case, since the voltage level of the telephone bell and the warning sound (hereinafter referred to as the "clack sound") for disconnecting the handset for a long period of time is high, it is transmitted to each subscriber circuit 361 without going through the switching element of the exchange circuit 309. ~364 are often sent directly to each subscriber 341~344.

Therefore, as shown in FIG. 1, a conduction state detection circuit 131 detects the conduction state of the switching element of the exchange circuit 109.
When each input line is grounded by the output of ~134, H1
When attempting to send out a ringtone, each subscriber's telephone receiver is in the off state, but the switching element of the switching circuit 109 is in a non-conducting state, so that it is grounded.

Therefore, the output of the howler sound signal source is grounded with low impedance, making it impossible to transmit it to each subscriber.

In order to prevent such a situation, the circuit shown in FIG. 3 does not use the conduction state detection circuit, but uses a telephone disconnection detection circuit 351, 352, 353 connected to each subscriber 341) to 344.
and 354, each incoming line is grounded, thereby reducing crosstalk and making it possible to transmit the howler sound.

In addition, in this case, each subscriber 341 to
When 344 is receiving a bell tone from each subscriber circuit 361 to 364, each subscriber is not on the receiver.

For this reason, a grounding circuit works, but generally the subscriber circuit 361
In the DC isolation circuit shown in Figure 4 in ~364, a transformer that couples only the frequency band of the signal to be exchanged is used, but since the frequency below the band is adopted for the ζζ bell sound, the actual There is no problem in the operation of sending out the bell sound.

In addition, in FIG. 3, reference numerals 321 to 324 are electronic circuits for controlling the relay contacts 311 to 314, respectively.

FIG. 4 is a diagram showing a specific example in which the inlet line 301 of FIG. 3 is grounded via a transformer.

In FIG. 4, a transformer 403 is used in the subscriber circuit 361 in FIG. It is being

The subscriber 401 has a DC isolation transformer 40 to prevent direct current from flowing between the incoming line 404 and the subscriber 401.
Exchange via 3.

It is connected to the incoming line 404 of the circuit, which is grounded by a relay contact 405 at the tertiary winding 413 of the transformer 403.

The subscriber 401 is in an off-hook state, such as during a call or when a ha-kura tone is being transmitted.

At some point, the direct current power source 407 causes a forward current to flow through the light emitting diode 412 of the photocoupler 402 that detects sushi, and the emitter of the photo transistor 411,
The collector becomes electrically conductive.

As a result, the input of the electronic circuit 406 is kept at zero potential.

Relay contact 405 is kept open.

On the other hand, when the subscriber 401 is in the on-hook state, no current flows through the light emitting diode 412, and the collector of the phototransistor 411 is maintained at approximately the power supply voltage E.

This causes current to flow through the relay winding of the electronic subcircuit 406, closing the relay contact 405 and grounding the tertiary winding.

In FIG. 3, reference numerals 408 and 409 are resistors for limiting the current flowing to the subscriber 401, and reference numeral 410 is a capacitor for DC blocking.

FIG. 5 is a diagram showing a third embodiment of the present invention.

As shown in FIG. 3, subscriber circuits 361 to 36 directly connected to each subscriber send out a bell tone to each subscriber 341 to 344.
4, the subscriber circuit of the called party may also supply the caller with a ringing tone indicating that the called party is ringing.

That is, in FIG. 3, if subscriber 343 is the caller and subscriber 341 is the called party, the subscriber circuit 361 sends out a bell tone to the called subscriber 341, and the switching circuit 3
A ring tone is provided to the originating subscriber 343 via the switching element 09.

In such a case, each input line 301 to 3 (as shown in Figure 3)
If the grounding of 04 is carried out under the control of the receiver removal detection circuits 351 to 354, the grounding is carried out even when the heavy bell tone is sent out, so the ringing tone is grounded with low impedance and cannot be supplied to the caller.

In the circuit shown in FIG. 5, in order to prevent such a situation, conduction state detection circuits 531 to 504 are connected to each input line 501 to 504 to detect the conduction state of the switching element of the exchange circuit 509.
34 are provided, respectively, and the outputs of the handset removal detection circuits 551 to 554 connected to the subscribers 541 to 544 and the outputs of the continuity state detection circuits 531 to 534 indicate that both the subscriber and the incoming line are not in use. The determination is made by the non-use state determination circuits 571 to 574, and the outputs of these determination circuits ground each incoming line, making it possible to supply the ringing tone in addition to the howler sound.

In FIG. 5, reference numbers 561 to 564 indicate DC insulation to prevent direct current from flowing between the power supply to each subscriber 541 to 544 and each incoming line 501 to 504 and each subscriber 541 to 544. This is a subscriber circuit that supplies telephone bell sounds, ha-kura sounds, etc., and has reference numbers 521 to 524.
is an electronic circuit for driving relay contacts 511-514.

FIG. 6 shows a specific example in which the inlet line 501 of FIG. 5 is grounded via a transformer.

In FIG. 6, a transformer 6 is connected to the subscriber circuit 561 of FIG.
03 is used, and the handset removal detection circuit 551 and the switching element conduction state detection circuit 53 of FIG.
1, optical coupling elements 602 and 612 are used, respectively.
Further, an AND circuit 611 is used as the unused state determination circuit 571 in FIG.

The subscriber 601 is connected to the incoming line 604 of the switching circuit via a DC isolation transformer 603 to prevent direct current from flowing between the incoming line 604 and the subscriber. This is done by a relay contact 605 in the tertiary winding 613 of the device 603.

The subscriber's handset is turned off and
Since the switching element of the hook state and exchange circuit 509 is in a non-conducting state, a forward current flows only through the light emitting diode of the optical coupling element 602 for detecting removal from the handset.

Furthermore, when a heavy bell signal is sent, the receiver of the called party is in an on-hook state, but in order to supply a ring tone to the caller, the switching element of the exchange circuit 509 is in a conductive state, and the optical coupling element is in a conductive state. A forward current flows only through the light emitting diode 612.

Also, during a call, subscriber 601 and incoming line 604
Since both are in use, a forward current flows through the light emitting diodes of both optical coupling elements 602 and 612.

As a result, the two inputs of the AND circuit 611 are connected to the collectors of the two phototransistors of the optical coupling elements 602 and 612, depending on whether the call is in progress, the sound is being sent out, or the bell sound is being sent out. Electric potential is applied.

However, in the three states described above, since a low level is applied to at least one of the two inputs of the AND circuit 611, a 01 level always appears as the output of the AND circuit 611, and this output keeps the relay contact 605 open. dripping

On the other hand, when both the subscriber 601 and the input line 604 are in an unused state, no forward current flows through any of the light emitting diodes of the optical coupling elements 602 and 612, and the two phototransistors of the optical coupling elements 602 and 612 The collector potentials of are kept approximately at the power supply voltages E1 and E2, respectively.

As a result, a high level is applied to all inputs of the AND circuit, so a high level appears at its output.

This output causes current to flow through the relay winding of electronic circuit 606, closing relay contact 605 and reducing crosstalk.

In FIG. 6, reference numeral 607 is a power source for supplying power to the subscriber, reference numerals 608 and 609 are resistors for limiting the current flowing to the subscriber, and reference numeral 610 is a capacitor for DC blocking. It is.

As described above, the use of the switching circuit of the present invention has the technical effect of significantly reducing crosstalk.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, FIG. 2 is a diagram showing a part of the circuit in FIG. 1, and FIG. 3 is a circuit diagram showing a second embodiment of the present invention. 4 is a diagram showing a part of the circuit in FIG. 3, FIG. 5 is a circuit diagram showing a third embodiment of the present invention, and FIG. 6 is a diagram showing a part of the circuit in FIG. 5. . In Figure 1, reference numerals 101, 102, 103 and 104 are incoming lines, reference numerals 105, 106, 107 and 108 are outgoing lines, reference numeral 109 is a switching circuit, reference numerals 111, 112, 113, 114, 115, 116. ,1
17 and 118 are relay contacts, reference number 12L122
゜123.124, 125, 126.127 and 12
8 is an electronic circuit, reference number 131,132゜133.13
4.135.136.137 and 138 represent conduction state detection circuits, respectively. In FIG. 3, reference numbers 301, 302, 303, and 304 are incoming wires, reference number 309 is a switching circuit, reference numbers 311, 312, 313, and 314 are relay contacts,
Reference numbers 321, 322, 323 and 324 are electronic circuits, reference numbers 341, 342, 343 and 344 are subscribers, reference numbers 351, 352, 353 and 354 are off-hook detection circuits, and reference numbers 361, 362.
, 363° and 364 represent subscriber circuits, respectively. In FIG. 5, reference numbers 501, 502, 503 and 504 are incoming lines, reference number 509 is an exchange circuit, reference numbers 511, 512, 513 and 514 are relay contacts,
Reference numbers 521, 522, 523 and 524 are electronic circuits, reference numbers 531, 532, 533 and 534 are continuity state detection circuits, reference numbers 541.542, 543 and 544 are subscribers, reference numbers 551.552.553
and 554 is a receiver removal detection circuit, 561, 562
563 and 564 represent subscriber circuits, and reference numerals 571, 572, and 574 represent unused state determining circuits, respectively.

Claims (1)

[Claims] 1. An incoming line group connected to a subscriber, an outgoing line group that intersects with the incoming line group, and, if necessary, interaction between required incoming lines and outgoing lines of these incoming line group and outgoing line group. In order to make a connection, a plurality of switching elements are provided at any intersection of these incoming lines and outgoing lines, and the switching elements connected to at least one of each incoming line or each outgoing line are connected to each other and the switching element is connected to at least one of each incoming line or each outgoing line and changes in current or voltage. a plurality of conduction state detection circuits that detect the conduction state of An exchange circuit comprising a plurality of short circuits that ground at least one of the wires. 2. In order to interconnect the incoming line group connected to the subscriber, the outgoing line group that intersects the said incoming line group, and the necessary incoming lines and outgoing lines of these incoming line group and outgoing line group as necessary, A plurality of switching elements provided at arbitrary intersections of these incoming lines and outgoing lines are connected to each of the incoming lines, and are configured to prevent direct current from flowing between the subscriber and the incoming lines. a plurality of direct current isolation circuits for detecting whether the subscriber has taken off the handset connected via these direct current isolation circuits, and a plurality of telephone removal detection circuits for detecting when the subscriber has taken off the handset, based on an output of the detection circuit when the handset has not been removed. 1. An exchange circuit comprising a plurality of short circuits that ground the input line with a sufficiently low impedance value in the frequency band of the signal to be exchanged. 3 An incoming line group connected to a subscriber, an outgoing line group that intersects with the incoming line group, and, if necessary, interconnections between the incoming line group and the required incoming line and outgoing line of these incoming line group and outgoing line group. A plurality of switching elements are provided at arbitrary intersections of the incoming lines and outgoing lines, and a plurality of switching elements are connected to each of the incoming line groups and detect a conduction state of the switching element by detecting a change in current or voltage. a continuity state detection circuit; a plurality of DC isolation circuits connected to each of the input lines for preventing direct current from flowing between the subscriber and the input lines; A plurality of handset disconnection detection circuits detect when a connected subscriber disconnects the handset, and the output of the continuity state detection circuit and the output of the handset disconnection detection circuit are used to detect a state in which the handset is not disconnected and each incoming line is not used. a plurality of determination circuits for determining the state in which the input signal is input at a sufficiently low impedance value in the frequency band of the signal to be exchanged when the handset is not removed and each incoming line is not used, according to the output of the determination circuit; An exchange circuit comprising a plurality of short circuits that ground lines.