JPS6228914B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a trunk circuit for transmitting and receiving signals in an automatic telephone exchange.

As a conventional trunk circuit for transmitting and receiving signals, a dual-line pulse type trunk used in a crossbar exchange can be considered, and this will be explained below with reference to FIG.

In Figure 1, relay J is a relay for detecting an incoming signal from the opposing station, and relay D is a relay for detecting a response signal (polarity inverted signal) from the opposing station when sending out, even if the line resistance between them is large. This is a polarized relay that can be operated with a small amount of current. These relays are inserted into the communication line even during a call to monitor the status of the game. The flow of communication current through these relays will greatly reduce the quality of communication, so wire rings RPT0 and RPT0 are installed in series with relays D and J to prevent crosstalk of these communication AC components.
RPT1 is inserted. As the incoming call signal from the other station forms a low-resistance loop between the communication lines A and B, the polarized relay J operates, and the incoming call is sent to the control circuit CONT via its contact j. Forward. The control circuit CONT prepares a register for counting dial pulses transferred from the game station following the arrival of this incoming call. Once this register is ready,
Sends a dial tone, etc. to the opposing team. The opponent station confirms this dial tone and sends out a dial pulse, but this dial information is also relayed by the polarized relay J, counted and accumulated in the register in the control circuit CONT, and connected to the extension telephone via the call path switch. be done. An extension telephone is connected to this trunk and operates relay E as a response signal to the opponent station to send a polarity reversal signal to the opponent station, but the polarized relay J is a relay in order to continue operation even when relay E is operated. Contact E uses a continuous contact. Therefore, even during a call, the polarized relay J continues to operate until the loop between the A and B lines due to low resistance is released as a recovery signal from the game player. Therefore, in the case of the local station being called first, only the E relay is restored and only sends a polarity inversion signal to the opposing station, and the polarized relay J continues to operate. After confirming the restoration signal from the receiving side, the game team opens the loop due to the low resistance between the A and B wires and restores the polarized relay J for the first time. This trunk is therefore free and available for the next outgoing/incoming call. This is a caller control recovery method (Calling Party Release) commonly used on leased line trunks to prevent collisions between outgoing and incoming calls.
It is called.

In other words, the call ends when the calling party recovers, and the called party calls first (recovers first).
Even if the calling party recovers, the call line must not be restored unless the calling party recovers, and this method facilitates the exchange of trunks in both directions.

The next time this trunk becomes the originating party,
Relays A and BA are activated by the information sent from the control circuit CONT, creating a low-resistance loop on the A and B lines and transmitting a start signal to the opposing team. Note that current flows through the polarized relay D in the opposite direction to its polarity, so it does not operate. When a dial tone or the like is returned from the opposing station as a dial pulse reception ready signal, the own station sends out a dial pulse to the opposing station by repeating the operation and recovery of relay A. While the dial pulse is being sent out, the C relay is operating and the BA relay is in the operating state, so an earth and open state (high impedance) pulse is sent to the A line.
A battery and open state (high impedance) pulse is sent to the B line. Only during dial pulse transmission, a potential opposite to the potential of the opposing station is output from the A and B lines, improving the pulse relay characteristics. Further, the circuit current is maintained by a low resistance loop except when dial pulses are being sent out. This polarized relay D is provided to detect the start of the game, and when it detects the recovery of the game, it sends the contact information to the control circuit CONT. A warning sound such as a tone is output to notify the player that the game has been restored. When the extension telephone is restored, relays A and BA will be restored, and the game station and your own station will also be restored.

In conventional trunks, the calling party releases the low-resistance loop between the A and B lines and recovers after a guard time of 600 msec or more, but the called party opens the low-resistance loop between the A and B lines from the calling party. From opening the loop of
It is designed to recover within 300msec. Therefore, if the called side has not completed recovery even after the calling side has a guard time of about 600 msec, the other station will continue to return a polarity inversion signal, resulting in a false call to the calling side, which is desirable from a traffic standpoint. isn't it. To prevent this, A line, B line
Some systems have wire rings and polarized relays between the lines, but since adding these circuits would require a large circuit, they are rarely installed in general double-wire pulse type trunks.

The conventional double-wire pulse type trunk circuit has been described above, but the polarized relays used in this are specially designed, and are expensive and large in size, resulting in problems in terms of mounting space. .
Therefore, it has the disadvantage that it is difficult to form trunk circuits on printed circuit boards in order to realize miniaturization of devices such as electronic exchanges. In addition, in order to prevent call loss, wire rings are required in addition to the polarized relay, which poses problems in terms of cost, mounting space, etc.
It has been difficult to construct a trunk circuit using such general-purpose small parts.

It is an object of the present invention to provide a trunk circuit for an automatic telephone exchange that is compact and operates stably, overcoming these drawbacks.

In order to achieve this object, the trunk circuit of the present invention has a diode blitz circuit whose first terminal and second terminal are inserted and connected in series to the DC current path of the trunk circuit, and whose voltage polarity is constant. It is characterized by comprising a circuit that detects the current direction using a transistor inserted and connected to the terminal, and a polarity reversal circuit that sends out a dial pulse by repeating the same potential and the opposite voltage as that of the game player.

These circuits can be constructed from inexpensive, small-sized components that are generally commercially available, and a small number of small relays can be used, resulting in an economical and compact trunk.

FIG. 2 shows an example of a trunk circuit according to the present invention.

When a low-resistance loop is formed between the A line and the B line as an incoming signal from the game, the ground - transistor 1 - OG contact - RLS contact - diode 2 - transistor 3 forming the limiter circuit, resistor 4 - Diode 5 - Transformer - B line - Low resistance of the opponent - A line - Transformer - Diode 6 - Transistor 7 forming the limiter circuit, resistor 8 - Diode 9 - Base and emitter of transistor 10 - OG contact - Transistor 11 - Battery The transistor 10 is saturated due to the current flowing through the path. For this reason, the input of IC12 becomes L level, and when H level information, that is, incoming information arrives at the control circuit IC terminal, the calling side goes to the game when ready to count and accumulate the dial pulses from the game that will subsequently arrive. Sends dial tone, etc. Subsequently, the incoming dial pulse connects the extension telephone to the trunk, and at the same time, as a response signal to the game, the P terminal of the control circuit CONT is set to L.
When the level changes from the high level to the high level, the output of the inverter 13 goes to the low level, turning on the transistor 14 of the polarity inversion circuit and turning off the transistor 11, so that the ground air is sent to the A line of the interface with the game player. On the other hand, due to the change of the P terminal from the L level to the H level, the output of the driver 15 is also at the H level, transistor 1 is turned off, and transistor 16 is turned on, so that the battery is sent to the B line of the interface with the game player. In other words, a polarity inverted signal is sent out as a response signal to the game, and the current in this case is as follows.

Earth - Transistor 14 - OG contact - Diode 17 - Transistors 7 and 8 forming the limiter circuit - Diode 18 - Transformer - A line - Low resistance loop of the opponent - B line - Transformer - Diode 1
9 - Transistor 3, resistor 4 - diode 20 - base emitter of transistor 21 RLS contact - OG contact - resistor 22 - transistor 16 - resistor 23 - battery that composes the limiter circuit.

As a result, the state changes such that the transistor 10 is restored (off) and the transistor 21 operates (on).
The IC terminal of the control circuit CONT, which is the output of IC12 and IC24, changes from H level to L level, and the RVS terminal changes from L level to H level. This allows the call state to continue from then on.

Next, in the case of a call to the local station (recovery to the called party), the P terminal of the control circuit CONT changes from H level to L level, thereby sending out a polarity inversion signal as a recovery signal to the opposing station. At this time, if the game still forms a low-resistance loop, the transistor 21 is restored and the transistor 10 is activated. After this, when the game opens the low resistance loop and the game recovers, transistor 1
0 is also restored. As a result, transistors 10 and 2
1 both recover and detect the recovery of the game. Therefore, the trunk can also be restored and used for making/terminating other calls.

On the other hand, when the game (calling side) calls first, the recovery of the game (calling side) can be detected by opening the low resistance loop of the game and causing both of the transistors 10-21 to recover. The detected control circuit CONT changes the P terminal from the H level to the L level, thereby bringing the entire trunk into the recovery state.

Also, a case will be explained in which this trunk becomes the calling side. First, in the control circuit CONT, when the OGC terminal is changed from the L level to the H level, and the P terminal is also changed from the L level to the H level, the relay OG operates to activate the game, and current flows through the next path. The essence of the game - B line - Trance -
Diode 19 - Transistor 3 forming the limiter circuit, Resistor 4 - Diode 20 - Base and emitter of transistor 21 - RLS contact - OG contact -
Resistor 25 - OG contact - Diode 17 - Transistor 7 forming the limiter circuit, Resistor 8 - Diode 18 - Transformer - A line - Battery for the game (-48V).

This allows the game to be activated by a low-resistance loop, and at the same time the control circuit CONT is activated by the operation of transistor 21.
The RVS terminal becomes H level. Next, when it becomes possible for the opposing station to count dial pulses, it starts transmitting dial pulses to the opposing station by replying with a dial tone or the like. The Hidenki OG recovers at the moment of the first break of the dial pulse, but this recovery time lasts until the digit interval is detected. The terminal P of the control circuit CON ₁ changes according to the dial pulse, and during the break of the dial pulse, a voltage with the same potential as that of the game player is applied, and during the make, a voltage with the opposite potential to the game game is applied. Its dial pulse relay has been improved. In the circuit operation when dial pulse is made, current flows through the following path.

Ground air - Transistor 14 - OG contact - Diode 17 - Transistor 7, resistor 8 - Diode 18 - Transformer - A line -
The first winding of the relay for dial pulse reception at the opposing station.
Battery; and the atmosphere of the opponent station - Dial of the opponent station - Second winding of the relay for pulse reception - B line - Transformer - Diode 19 - Transistor 3 and resistor 4 forming the limiter circuit - Diode 20 - Base and emitter of transistor 21 - rls→contact-og
Contact - Resistor 22 - Transistor 16 - Resistor 23 -
It's so bad.

In this way, current flows and the make rate is improved by speeding up the operating time of the dial pulse receiving relay of the opposing team during the make. In other words, the reason why the double-wire pulse method is adopted is that when a dial pulse meter signal is transmitted via a long-distance line, the rise time (the time it takes for the relay to operate) of the dial pulse receiving relay is delayed, causing The make time is improved by applying a voltage with a reverse potential so that the make time does not become too short. When the opposing station finishes receiving the dial pulse and returns a polarity inversion signal as a response signal, current flows through the next path.

The essence of the game - A line - Transformer - Diode 6 -
Transistor 7 and resistor 8 forming the limiter circuit
- Diode 9 - Base/emitter of transistor 10 - OG contact - Resistor 25 - OG contact - RLS contact -
Diode 2 - Transistor 3 that makes up the limiter circuit, Resistor 4 - Diode 5 - Transformer - B line - Battery for the game.

As a result, the operation of the transistor 10 and the recovery of the transistor 21 detect the response of the game by the change from the L level to the H level of the IC terminal of the control circuit CONT and the change from the H level to the L level of the RVS terminal, and after that, the communication state is established. becomes.

Next, if the trunk on the transmitting side is restored first, the relay is activated by changing the RLSC terminal of the control circuit CONT from L level to H level.
RLS operates, opens the loop to the opposing team, and sends a recovery signal. From this point on, the RS of the output of the comparator circuit 26 connected between the A line and the B line
The operation of the relay RLS continues until the potential at the terminal changes from the L level to the H level, and the relay OG also continues its operation. This means that after opening the low-resistance loop to the opposing station, the opening of the loop continues until the opposing station reverses the polarity as its recovery signal, and the relay RLOG is configured not to be restored before the recovery of the opposing station is completed. Prevents false calls.

On the other hand, if the called side (opposite side) recovers first, it will send a polarity inversion signal as recovery information for that game, so it can be detected by the recovery of transistor 10 and the operation of transistor 21. The output of the comparator 26 also changes from L level to H level. This allows relay OG
Then, restore the relay RLS and make the trunk free. FIG. 3 shows a time chart at each point when the above-mentioned trunk becomes the calling side.

Technically considering the effects of the present invention, the present invention is characterized by the fact that the present invention alternately repeats the pulse that becomes the A-line battery and the B-line battery, and the pulse that becomes the A-line battery and the B-line battery. By sending out a dial pulse, when the dial pulse is off, the potential of the own station is forced to match the potential of the opposing station to the same potential, improving the sharpness of the dial pulse (when the dial pulse is off). This has the effect of sharpening the off-state action. In the conventional example, when the dial pulse is off, the dial pulse sending circuit has a high impedance, and the discharging current flows due to the distributed capacitance existing in the cable etc. leading to the game, and the make time of the dial pulse is shortened. It also has the effect of preventing the battery from becoming too long, but this A-line battery, B-line battery, or
The original purpose of the present invention, which transmits and receives signals as a line battery and a B line, is to operate the relay E as a response signal to the game via the e contact - RPT ₁ - J relay in Fig. 1 in the conventional example. This is a configuration for sending out a polarity inversion signal to the opposing station, and the great effect of the present invention is that such a configuration can also be used to send out dial pulses. In other words, the A relay (BA, C relay) for dial pulse sending in the conventional example and the E relay for polarity reversal.
It can be seen that the present invention has a great effect in that the relay, RPT ₁ , and J relay can be used in common with the A-line battery, B-line battery, or the circuit that becomes the A-line battery and B-line battery. .

The above has described a trunk circuit that has the same function as a dual-line pulse type trunk circuit using a polarized relay and a crosstalk prevention wire used in a crossbar converter, etc., but the present invention furthermore operates only when making a call. Instead of using relays for various purposes such as relays, relays that operate only when a call is received, and relays that operate only during dial pulses, we aim to extend the life of relays by using semiconductor elements, and we can also construct them using small, commercially available parts. Since this is possible, it is possible to reduce the mounting area of the components and at the same time create an inexpensive and economical circuit configuration.

It should be noted that the present invention is not limited to the above embodiments, but can be modified in various ways as necessary. For example, although the double-wire pulse system has been described as an example of this circuit, it is obvious that it can also be used for a booster battery system.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a two-line pulse type trunk of a conventional automatic telephone exchange, FIG. 2 is a circuit diagram of a two-line pulse type trunk of an automatic telephone exchange according to the present invention, and FIG. 3 is a trunk circuit diagram of the trunk shown in FIG. 2 according to the present invention. FIG. 2 is a diagram illustrating a case where a person becomes a calling party (originating party). 10, 21... Current direction detection transistor,
1, 11, 14, 16... Transistors for reversing power supply polarity.

Claims (1)

[Claims] 1. In a trunk circuit of an automatic telephone exchange that transmits and receives signals between the two automatic telephone exchanges by direct current flowing through a telephone line connecting the two automatic telephone exchanges, the first terminal and the second two diode bridges whose terminals are inserted and connected in series to the DC current path to keep the voltage polarity of the constant current circuit constant; a current direction detection circuit that includes transistors that are inserted and connected to the two diode bridges respectively; connection means for respectively connecting first terminals of the two diode bridges to the telephone line; an earth supply transistor and a power supply transistor connected to the second terminals of the two diode bridges, respectively; When supplying earth air to the second terminal of one diode bridge, supplying power to the second terminal of the other diode bridge, and supplying power to the second terminal of one diode bridge. has ground air/power supply means for supplying ground air to the second terminal of the other diode bridge, and generates a dial pulse by repeatedly sending out voltages of the same potential and opposite potential as the game player via the telephone line. A trunk circuit for an automatic telephone exchange, comprising dial pulse sending means for sending out a dial pulse.