JP2504566B2 - Office line trunk circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention relates to a trunk line trunk circuit which is connected to a subscriber line of a central office switch to prevent outgoing / incoming collisions, and a primary line detection and a reversal detection can be shared by the same circuit. For the purpose of providing a trunk, one end is provided with a primary signal / reversal detection means connected to the B line for communication, and the other end of the primary signal / reversal detection means is grounded when the DC loop is not closed. Switch to connect to the A line for communication when the DC loop is closed.
The switching means and the second switching means for forming a connection of the ringing signal detecting means between the line A and the line B when the DC loop is not closed are provided, and the primary line is selected depending on whether the loop for the central line is closed or not. The detection output of the signal / reversal detection means is configured to identify whether it is the response state of the other party when the call is made or the call state when the call is received.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trunk line trunk circuit that is connected to a subscriber line of a central office switch to prevent outgoing / incoming collision.

The subscriber line accommodated in the central office switch may be connected to a single telephone or may be connected to a private branch exchange (PBX) or a device containing a plurality of telephones such as a key telephone device. The private branch exchange and the key telephone device are provided with a trunk line trunk as an interface circuit for the communication line of the central office switch, and are used for both normal outgoing call and incoming call (the outgoing call and the incoming call may be separated in some cases. ).

However, when making an outgoing call using a trunk line that also serves as an outgoing / incoming call, if an incoming / outgoing call is made from this switch to the trunk, a outgoing / incoming call collision will occur. Has been done.

[Prior Art] FIG. 4 is a block diagram of a conventional private branch exchange, FIG. 5 is a block diagram of a conventional office line trunk, and FIG. 6 is a time chart of the conventional example.

In FIG. 4, T-SW is a time division switch that represents a speech path switch, TEL is a number of extension telephones accommodated in a private branch exchange, LC is an extension subscriber circuit, and COT is a local trunk that is connected to a central office switch. , PVT is a trunk trunk, LPR is a line processor that controls subscriber circuit LC and trunk, MM
Represents a memory and CC represents a control device.

In this conventional example, a time division switch is used as a speech path switch, but there is also one using a crossbar switch.
When a call is made from the extension telephone TEL to the central office line, if the central office line is empty at that time, the central office trunk COT is captured by the action of the control unit, memory MM and line processor LPR and connected to the central office exchange (not shown). Then, the user is connected to the other party via the public telephone network by dialing.

The configuration of a conventional office line trunk will be described with reference to FIG.

In FIG. 5, the subscriber line of the central office switch is connected to this trunk line trunk (COT) as a central line, and two lines A and B are connected.
It is represented by two lines, usually from the central office switch to -48V on the A line,
Geoelectricity is being supplied to the B line.

In this station line trunk, 50 is a levers that detects that the polarities of the A and B lines are reversed when the other party answers after making a call from the extension to the central office switch through this station line trunk and dialing. Detecting section 51 is a primary signal detecting section for detecting a primary signal expressed by the voltage of -48V being transmitted from the central office switch to the B line at the time of an incoming call, and 52 is a central line trunk from the central office to this central trunk. A ringing signal detection unit that detects a ringing signal (ringer) of 16 Hz with a 1-second on and 2-second off cycle that arrives when an incoming call arrives.

Further, 53 and 54 represent relays A and B, respectively, both of which are relays for closing a DC loop, and the relay A is used when sending dial pulses. 55 is a C position circuit for preventing pulse distortion during dial pulse relay, T is a 2-wire to 4-wire transformer, BN is a balanced circuit (balance network), and VR is a varistor for overvoltage protection.

From each part of the revers detector 50, the primary signal detector 51, and the ringing signal detector 52, RV (revers), BD (battery detect), and RG (ringer) are output as signals indicating the detection state. Monitoring signal (displayed in SCN: scan)
Is constantly monitored by LPR. In addition, each relay A, B, C
The (C position) is driven by a signal distribution unit SD (signal divider) of a line processor (hereinafter referred to as LPR).

FIG. 6 shows a time chart of the conventional trunk line trunk shown in FIG.

The operation upon receipt of an incoming call will be described with reference to the time chart shown in FIG.

When there is an incoming call, the relay B is off, so the primary signal detection unit 51 detects -48V on the B line via the contact b, and the signal S
P becomes “1”. When a ringing signal (ringer) arrives at the same time as or after the primary signal, the ringing signal detector 52
Is driven and the signal RG becomes "1" as a detection output.

The LPR notifies this information to the control device CC via the T-SW (Fig. 4), and the relays A and B, which close the loop in which the operator answers the call, are driven by the LPR. The incoming connection is connected to the operator via the T-SW of the exchange. Since the ringing signal continues periodically as described above, even if there is an instruction to send an incoming call, the ringing signal is sent immediately or after a delay depending on the state of the ringing signal generation circuit at that time. Be seen. Therefore, it is necessary to detect the primary signal in order to detect early that there is an incoming call.

Next, the operation at the time of calling will be described with reference to the time chart shown in FIG. 6B.

When a call is transmitted from the extension line through the station line trunk, the relay A and the relay B are turned on by the control of the LPR, and a DC loop is formed by switching the contacts a and b with respect to the central office switch. Then, when the dial operation is performed, the dial pulse is sequentially sent to the central office switching equipment as shown in the figure by the control of the LPR. Connection to the other party is made by the operation of the central office switch, and the polarities of the A and B lines are reversed in the central office switch to which the other party answers, so that the A wire becomes ground and the B wire becomes -48V. When this is detected by the reversing detection unit 50, the reversing detection signal (RV) becomes "1" and is notified to the LPR. The outgoing / incoming operations are performed as described above. This is done as follows.

That is, when there is a call from the station, the primary signal detection unit 51
Is driven, and its detection signal BD is notified to the LPR, which is sent to the control device CC (Fig. 4), but at the same time as this, when there is an office line call from the extension telephone TEL (Fig. 4). , The control device CC controls so as not to capture this station line trunk. In that case, control is performed such that other vacant station line trunk is captured if it is available, and busy (busy tone) is transmitted if it is not vacant.

[Problems to be Solved by the Invention] As described above, in the conventional office line trunk having the function of preventing outgoing / incoming call collisions, the primary signal detection unit detects the polarity reversal of the B line at the time of the incoming call, and detects the levers. Department is A when making a call
Although the polarity reversal of the lines B and B is detected, there is a problem that it is uneconomical to have two circuits in order to perform similar functions.

An object of the present invention is to provide an office line trunk capable of sharing primary signal detection and reversal detection in the same circuit.

[Means for Solving the Problems] FIG. 1 is a principle configurational diagram of the present invention.

In FIG. 1, reference numeral 10 denotes a polarity reversing mechanism at the time of responding to the other party, which is provided in the publicly known central office switch, 11 is a primary signal and ringing signal transmitting mechanism at the time of incoming call, which is also provided in the publicly known central office exchange, 12 to
Reference numeral 17 represents each part of the trunk line trunk, 12 is a primary signal / inversion detecting means, 13 is a calling signal detecting means, 14 is an A line, 15 is a B line,
Reference numeral 16 represents a first switching means, and 17 represents a second switching means.

The present invention performs detection of a primary signal and detection of an inversion signal (revers) in the same circuit in an office line trunk equipped with a call origination / termination collision prevention function, and the detection output is the A line / B line at that time. It is identified as an inverted signal or a primary signal depending on whether or not the DC loop through it is closed.

[Operation] First, in the normal state, the first switching means 16 and the second switching means 17
Are both in the state shown in the figure, and when the incoming state is reached, the primary signal (-48V) is sent to the B line 15 by the primary signal of the central office switch and the ringing signal sending mechanism 11, and the ringing signal is sent to the A line. To be done.

The primary signal drives the primary signal / inversion detection means 12 of the trunk line trunk and generates a detection signal 121. Further, the arrival of the calling signal is detected by the calling signal detecting means 13 to detect the detection signal 131.
Is generated. The detection signals 121 and 131 are LPR (not shown).
In the LPR, the DC loop is not closed in this state (incoming state). Therefore, when the detection signal 121 is received, it is identified that there is an incoming call.

In the calling state, when there is a call from the extension telephone through the office line, the vacant office line trunk is captured by the LPR, and the control for closing the DC loop is performed, and the first switching means 16 and the second switching Both means 17 are switched to a state opposite to that shown. Subsequently, when a dial pulse is sent, the exchange is connected to the other party through the central office line, and when the other party responds, the switching contact 101 of the polarity reversing mechanism 10 at the time of response provided in the central office exchange is driven to polarize. Invert and supply -48V to the A line and ground to the B line.

In the trunk line trunk, this is the primary signal / inversion detection means.
12 is driven to generate a detection signal 121. This detection signal 1
Although 21 is notified to the LPR, since the DC loop is controlling to close the DC loop at this time, the detection signal notified at this time is
When 121 is received, it is identified as a polarity inversion signal by the response.

[Embodiment] FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is a primary signal
It is a figure which shows the specific structural example of a reversing detection circuit.

In FIG. 2, 20 is a primary signal / reverse detection circuit,
Reference numeral 21 is a C position relay, 22 is a ringer detection circuit, 23 is a relay A and a relay B, and other T, BN, RV, etc. are the same as in the conventional case.

In this embodiment, the primary signal / reverse detection circuit 20
The detection signal BD / RV from the LPG together with the ringer detection circuit 22 is LPR.
To be sent as a supervisory signal (displayed in SCN). Also, LPR
Control signals for driving the relays A, B, and C position relays are supplied from the signal distributor SD in the same manner as in the conventional case.

 The operation of the embodiment will be described below.

First, the operation at the time of incoming call will be described. The time chart is the same as that in Fig. 6A.

In the normal state, since the B line is at the ground potential, no current flows in the primary signal / revers detection circuit 20. (In this state, transmission is possible.) In the incoming state, the B line potential becomes −48V and the primary signal / reverse detection circuit 20 detects this and notifies the signal BD / RV to “1” to the LPR.

After that, when a ringing signal is sent from the station, the ringer detection circuit 22 detects this and sets the signal RG to "1" to notify the LPR. When the operator responds, the LPR causes the relay A and the relay B to respond.
Will be driven into a call.

With the above operation, the output of the primary signal / reverse detection circuit 20 is not identified as a revers signal.

Next, the operation at the time of call origination will be described. The following operations will be performed in order, and the time chart is the same as in FIG. 6B.

 You can make a call in the normal state.

The trunk of the station line is captured for transmission of the station line, the relay A and the relay B are driven by the signal distributor SD, and the DC loop is closed. Then, a dial pulse is transmitted from the contact a of the relay A.

When the called party is called by the operation of the central office switch and responds, a reversal signal (polarity reversal signal) is sent from the central office side, which is detected by the primary signal / reversal detection circuit 20 and the detection signal BD / RV is output. When it occurs, it is notified to LPR, and the call becomes active.

As described above, in the outgoing state, the relay loop is closed by the relays A and B, so that the reversal signal is not identified as the primary signal.

Although the primary signal and the reversal signal have the same characteristics as described above, the function to prevent the collision of incoming and outgoing calls by distinguishing them by reading the meaning of the signal depending on the difference between the time when the call originates and the time when the call arrives It will be possible to do as well as technology.

Next, FIG. 3 shows a concrete example of the configuration of the primary signal / reverse detection circuit.

The configuration of A. in FIG. 3 is a circuit using a photocoupler PC, and when transmitting in a normal state, the DC loop current flows through the diode D from the B line side to the A line side. However, when the primary signal arrives at the other party's response or at the time of incoming, the light emitting diode of the photocoupler PC becomes conductive and emits light, and the light receiving transistor receives light and the detection signal BD
/ RV is generated.

The configuration shown in FIG. 3B is a circuit using a differential amplifier OP,
A resistor R is provided between the B line and the line extending to the A line side, and the potential at both ends of the resistor is detected to determine that the B line side potential is more negative than the A line side potential. Detected by the amplifier OP, the detection signal BD / RV is generated.

[Effects of the Invention] According to the present invention, cost can be reduced by sharing the polarity inversion detection circuit and the primary signal detection circuit as compared with the conventional circuit, and the circuit space can be reduced by reducing the number of circuits. Can be reduced and the device can be downsized.

[Brief description of drawings]

FIG. 1 is a block diagram showing the principle of the present invention, FIG. 2 is a block diagram showing an embodiment,
FIG. 3 is a diagram showing a concrete example of the configuration of the primary signal / levers detection circuit, FIG. 4 is a diagram of a conventional private branch exchange, FIG. 5 is a diagram of a conventional office line trunk, and FIG. Is a time chart of a conventional example. In FIG. 1, 10: Polarity inversion mechanism of central office switch 11: Primary signal and ringing signal sending mechanism of central office exchange 12: Primary signal / reversal detecting means 13: Ringing signal detecting means 14: A line 15: B Line 16: first switching means 17: second switching means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyofumi Hayashi 2-18-2 Nishigotanda, Shinagawa-ku, Tokyo Inside Hasegawa Electric Co., Ltd. (72) Inventor Yoshinobu Okabe 1-19 Nishiki-cho, Naka-ku, Nagoya-shi, Aichi No. 24 within Fujitsu Nagoya Communication System Limited

Claims (1)

(57) [Claims] 1. A station line trunk circuit connected to a subscriber's line of a central office switch for preventing outgoing / incoming collisions, wherein a primary signal / reverse detection means having one end connected to a B line for communication is provided, The other end of the next signal / reversal detection means is connected to the earth when the DC loop is not closed, and is switched to be connected in series with the A line for communication when the DC loop is closed; Second switching means for forming a connection of the ringing signal detecting means between the A line and the B line when the line is not closed, and the primary signal / reverse detecting means depending on whether or not the loop for the central line is closed. A station line trunk circuit characterized by distinguishing whether the detection output of the call is the other party's response status at the time of calling or the calling status at the time of incoming.