JPH0575700A - Ringer transmission circuit for subscriber circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a ringer transmission circuit that suppresses impulse noise generated when a ringer signal of a subscriber telephone is stopped in a subscriber circuit of a telephone exchange or a subscriber transmission device. To do. [Structure] Ringer generating circuit 2, ringer relay switching means 10, ringer current detection circuit 40, ring trip circuit 51, ringer relay control means 60, ringer relay drive means 70, ringer current phase detection means 80, and ringer current phase The detection circuit 80 detects the zero-cross point of the AC signal included in the ringer signal, generates the ringer stop control clock signal, and outputs the ringer relay drive means 7.
At 0, the ringer relay control signal and the ringer stop control clock signal are used to drive and restore the ringer relay at the zero crossing point of the ringer current phase, and the ringer signal of the subscriber telephone 1 is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ringer sending circuit used in a subscriber circuit of a telephone exchange or a subscriber transmission device.

When a caller calls a telephone subscriber, the caller dials to ring the bell of the telephone subscriber's telephone of the other telephone subscriber. When the ringer signal is stopped by this switch, noise may be generated from the subscriber circuit that is sending the ringer signal and leak into the other line during the call, and a countermeasure is desired.

[0003]

2. Description of the Related Art An example of a conventional ringer sending circuit of a subscriber circuit is shown in FIG. When a caller on the transmission line side (not shown) rings a telephone subscriber, the bell of the telephone set 1 for the subscriber of the telephone subscriber rings, but the calling signal from the calling party is CODEC3.
1 is sent from the ringer relay control circuit 61 to the ringer relay drive circuit 71, and the ringer relay drive circuit 71 drives the ringer relay contact 11A / 11B of the ringer relay circuit 11 to move to the ringer relay contact 11A / 11B of FIG. Switching from the thick solid line contact side to the dotted line contact side, and from the ringer generation circuit 2, intermittent, for example,
An AC signal of 70 V and 20 Hz as shown in FIG. 4 (1) is supplied to the ringer current detection circuit 41 and the ringer relay circuit 1
It is sent to the telephone line 6 via 1 and the bell of the subscriber's telephone 1 is intermittently rung.

The ringing of the bell is continued until the subscriber goes off-hook on his or her own telephone set 1 for subscribers or the calling party goes on-hook for his or her own telephone set 1 for subscribers. When the subscriber off-hooks his or her own telephone set 1 for subscribers, a direct current flows by superimposing it on the ringer signal from the ringer generation circuit 2, and the ring trip circuit 51 detects this direct current and the ringer signal changes from positive polarity to negative polarity. At a certain fixed point of time, a ringer signal transmission stop command is issued to the ringer control circuit 61 so that the ringer relay contacts 11A / 11B are restored, and the ringer relay drive circuit 71 outputs a drive operation stop signal. Switching to the thick solid line side of the ringer relay contacts 11A / 11B shown in (4), and thereafter, a call with the calling party starts.

When the caller hooks his / her subscriber telephone set 1 on-hook, a ringer stop signal sent from the transmission line side via the CODEC 31 acts to restore the ringer relay contacts 11A / 11B. ..

[0006]

In these devices, a large number of subscriber circuits 3 are connected to subscriber telephones 1 via communication lines 6, respectively.

While each subscriber circuit 3 is in a call, transient noise may be generated and affected by the ringer sending circuit of another subscriber circuit 3. This noise is called impulse noise, and the source of this impulse noise is when the ringer signal is stopped because the load of the subscriber circuit 3 sending the ringer, that is, the subscriber telephone set 1 is an inductive load. , The back electromotive force is generated from the load, and it becomes impulse noise and leaks into other lines during a call. At a certain point in time when the ringer signal changes from the positive polarity to the negative polarity, the ringer signal current is not always the same depending on the load. Without
In particular, there is a problem that it causes a bit error when performing data communication with a modem or the like.

An object of the present invention is to solve the above problem and to provide a ringer sending circuit of a subscriber circuit for suppressing impulse noise generated when the ringer signal is stopped.

[0009]

FIG. 1 is a block diagram showing the principle of a ringer sending circuit of a subscriber circuit according to the present invention. In the figure, 1 is a telephone for subscribers, 2 is a ringer generation circuit, and 10 is a circuit.
Is a ringer relay switching means, 11 is a ringer relay contact, 20 is a power feeding and voice signal transmitting / receiving means, 40 is a ringer current detecting means, 51 is a ring trip circuit, 60 is a ringer relay control means, 70 is a ringer relay driving means, and 80 is It is a ringer current phase detection means.

According to the present invention, based on the ringer signal generated by the ringer generator 2, the ringer signal is sent to the subscriber's telephone 1, and the subscriber's telephone 1 and the ringer generator 2 are transmitted based on the ringer signal. And a ringer current detecting means 40 for detecting a ringer current flowing between the subscriber telephone 1 and a ringer relay switching means for switching between connecting a ringer signal to the subscriber telephone set 1 or connecting a voice signal from the transmission line side. 10 and the ringer current detection circuit 4
A ring trip circuit 51 that detects the output of 0, detects the off-hook of the subscriber, and sends a ringer signal stop signal.
And a ringer relay control means 60 for transmitting a ringer relay control signal in response to a ringer signal drive signal from the caller, a ringer signal stop signal, or a ringer signal stop signal from the ring trip circuit 51, and the ringer relay. A subscriber of a switchboard or a subscriber transmission device configured with a ringer relay drive signal for receiving a ringer relay drive signal from the control means 60 and transmitting a ringer relay drive signal for switching the ringer relay contact 11A of the ringer relay switching means 10. In the ringer sending circuit of the circuit, a ringer current phase for detecting a zero-cross point of an AC signal included in the ringer signal input from the ringer current detecting means 40 and generating a ringer stop control clock signal having the zero-cross point as a rising point. Detection means 8
Set 0.

Then, the ringer relay drive means 70
A ringer relay drive signal is sent using the ringer relay control signal from the ringer relay control means 60, and the operation of the ringer relay is performed at the rising point of the ringer stop control clock signal from the ringer current phase detection means 80. By adding a ringer relay drive signal transmission stopping means for restoring the ringer relay signal, the ringer relay switching means 10 is restored at the zero cross point of the AC signal included in the ringer signal, and the ringer signal of the subscriber telephone 1 is stopped. , Can achieve the purpose.

[0012]

According to the present invention, in the conventional subscriber circuit,
A ringer current phase detecting means 80 for detecting a zero-cross point of an alternating current signal included in the ringer current detecting means 40 is provided, and the ringer current driving means 70 sends the ringer current phase detecting means 80 to the ringer current phase detecting means 80. A point at which the ringer current becomes zero by adding a means for generating a signal for switching the ringer switching means 10 by the ringer stop control clock signal and the ringer relay control signal sent from the ringer relay control means 60. That is, a point at which the AC signal included in the ringer signal crosses zero is detected, and at that time, the ringer relay drive means 70 drives the ringer relay switching means 10 to restore the ringer relay contacts 11A / 11B to restore the ringer signal. Can be stopped, so the generation of impulse noise It is possible to suppress.

This is because the inductive load acts so as to prevent the current from changing, so if the Ringer signal is stopped while a large current is flowing, a large counter electromotive force is generated in an attempt to maintain the current. When the current is minimum, the Ringer signal is stopped and the back electromotive force is minimized.

[0014]

EXAMPLES Examples will be described with reference to FIGS. 2, 3 and 4. FIG. 2 shows an example of a ringer transmission circuit block diagram of the subscriber circuit 3 according to the present invention. In FIG.
The same reference numerals as those in FIG. 5 indicate the same components, 31 is a CODEC for converting a PCM digital signal sent from the transmission line side into a voice signal, and 81 is a Ringer current phase detection circuit.

FIG. 3 shows a concrete circuit example related to the Ringer current phase detection circuit 81 in FIG.
R1 to R8 are resistors, OP1 is an operational amplifier, C1 is a capacitor, CO1 is a comparator, D1 is a diode, and B.
U1 is a buffer, DL1 to DL2 are delay circuits, EX1
Is an EX-NOR circuit, and FF1 is a flip-flop added by the present invention. Further, NO1 is a NOT circuit, NA1 and NA2 are NAND circuits, RL1 is a Ringer relay, and TR1 is a transistor.

FIG. 4 is a diagram showing a time chart in the embodiment of FIG. 2, in which parentheses (1) to (9) are shown.
3 indicates the signal waveform at the place indicated by the same parenthesized reference in FIG. 3 or the operation recovery of the relay. (1) is a voltage waveform of the ringer signal generated by the ringer generation circuit 2,
(2) is a ringer current waveform that flows when the subscriber telephone 1 which is a load is connected, (3) is an output waveform of the comparator CO1 of the ringer current phase detection circuit 81,
(4) is the output waveform of the delay circuit DL1, (5) is EX-N
An output waveform of the OR circuit EX1 is a ringer stop control clock signal, (6) is an output of the ringer control circuit 91, a ringer relay control signal, (7) is an output waveform of the NAND circuit NA1, and (8) is an operation of the ringer relay RL1. (9) is the ringer relay contact 11A / of the ringer relay circuit of FIG.
11B shows a contact state of the contacts of 11B.

The operation will be described with reference to FIG. 3, which is a specific example of the block diagram of FIG. The present invention is different from the conventional example in that the switch is conventionally turned on / off at a certain point in time when the ringer signal changes from the positive polarity to the negative polarity, but the present invention detects the timing when no noise occurs in the telephone used. At that time, the switch is turned on / off to operate the ringer relay RL1.

That is, as shown in FIG. 2, a ringer current phase detection circuit 81 is inserted between the output of the ringer current detection circuit 41 and the ringer relay drive circuit 71. The ringer signal output from the ringer generator 4 is sent to the ringer relay circuit 11 via the ringer current detection circuit 41.
On the other hand, the output of which the ringer current detection circuit 41 has detected the ringer current waveform is sent to the ring trip circuit 51 and simultaneously to the ringer current phase detection circuit 81.

Here, when the calling signal of the subscriber telephone set 1 is sent from the caller on the transmission line side, the calling signal is sent from the ringer relay control circuit 61 to the ringer relay drive circuit 71, and the ringer relay circuit 11 is sent. Switch the ringer relay contact 11A of.

By this switching, the ringer signal shown in (1) of FIG. 4 generated by the ringer generator 4 is sent to the subscriber telephone set 1 through the ringer current detection circuit 41. on the other hand,
The current waveform detected by the Ringer current detection circuit 41 is shown in FIG.
The waveform becomes as shown in (2) of (1) and is sent to the ring trip circuit 51, and at the same time, the ringer current phase detection circuit 81
Also sent to.

The signal waveform sent to the ringer current phase detection circuit 81 has its direct current component cut by C1 in the comparator CO1 and is input to the non-inverting input terminal which is the + input terminal. The voltage of the input signal waveform is 0V compared with the voltage (= 0V) of the inverting input terminal, which is the input terminal.
The higher + side waveform part becomes almost Vcc voltage, and 0 V
The lower-side waveform portion has almost the -Vcc voltage. After that, in the diode D1, the output waveform portion having the −Vcc voltage is cut to 0 V, and has a waveform as shown in FIG. 4 (3).

Next, the comparator output waveform whose negative side waveform has been cut by the diode D1 is branched and is composed of, for example, a capacitor and a resistor, and the ringer relay RL1 is used.
4 is sent to the delay circuit DL1 adjusted so as to be delayed by a time corresponding to the operation delay time of the delay circuit DL1 and delayed there. As a result, the output signal of the delay circuit DL1 is delayed as shown in FIG. The signal is delayed by a time corresponding to the operation delay time of the ringer relay RL1 as compared with the input signal of DL1.

Next, the delayed signal and the signal before being delayed are input to the EX-NOR circuit EX1.
Since L is output when the two input signals are different,
The output signal of the EX-NOR circuit EX1 has a pulse width corresponding to the delay time of the ringer relay RL1 as shown in FIG. 4 (5). This signal is input to the CK terminal of the flip-flop FF1 of the ringer relay drive circuit 71 as a ringer stop control clock signal.

When stopping the ringer signal for ringing the bell of the subscriber telephone set 1, the ringer signal stop signal sent from the ring trip circuit 51 or the CODEC 21 is sent from the ringer relay control circuit 61 as a ringer relay control signal. The ringer relay drive circuit 71
Sent to. In the conventional example, the ringer relay RL1 is immediately restored when the relay recovery signal (= 0V continuous signal) of the ringer relay control signal is sent to the ringer relay drive circuit 71.

However, in the present invention, the ringer relay RL1 recovers at the timing of the ringer relay control signal and the ringer stop control signal clock signal which is the output of the ringer current phase detection circuit 81. That is, the relay recovery signal of the ringer relay control signal is the flip-flop F.
At the first rising edge of the ringer stop control clock signal after being input to the D terminal of F1, the Q output of the flip-flop FF1 changes from H (= + 5V) to L (= 0V).
Becomes

Next, the Q output signal of the flip-flop FF1 is input to the NAND circuit NA1 of the set / reset / latch circuit LA1 composed of the NAND circuits NA1 and NA2. Further, the signal input to the NOT circuit NO1 is changed as the ringer relay control signal is converted from the relay operation signal (H) to the relay restoration signal (L).
Since the output signal of the NAND circuit is converted from L to H, the NAND circuit N
The output of A2 changes from H to L.

When the output of the NAND circuit NA2 is changed from H to L, the transistor TR1 which has been on until then is turned off, and the operation of the ringer relay RL1 which was in operation is stopped and restored. ..

The NOT circuit NO1 and the NAND circuit N
A1 and NA2 are for causing the operation of the transistor TR1 to follow the Ringer relay control signal and maintain the operation.

If an abnormality occurs in the ringer current phase detection circuit 81 during transmission of the ringer signal to the subscriber telephone set 1 and the ringer signal stop control clock signal is no longer transmitted, the ringer relay RL1 is restored. Can not be. Therefore, the ringer relay drive circuit 71
The delay circuit DL2 is provided between the output of the ringer relay control circuit 61 and the input of the NAND circuit NA1 so that the set / reset / latch circuit LA1 can be forcibly reset, and the delay time of the delay circuit DL2 is set to the ringer signal period. (50 msec if the frequency is 20 Hz) 1 /
By taking a time longer than 2, for example, about 50 to 100 msec, although impulse noise cannot be suppressed, the ringer relay RL1 is delayed by the delay time.
Since it can be restored, it can be used as a conventional function.

[0030]

As described above, according to the present invention,
Using the ringer signal current that actually flows, the ringer current phase detection circuit detects the zero-cross point of the AC signal included in the ringer signal from the output waveform of the ringer detection circuit and generates the ringer stop control clock signal. The same effect is effectively exerted on the suppression of impulse noise irrespective of the difference in inductive inductance or the like depending on the type of telephone, so that it can be similarly used for any load of subscriber telephones and the like.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of a ringer transmission circuit of a subscriber circuit according to the present invention.

FIG. 2 is a block diagram showing an embodiment of a ringer sending circuit of a subscriber circuit according to the present invention.

FIG. 3 shows a specific example of a ringer transmission circuit of the subscriber circuit of FIG.

FIG. 4 is a diagram showing a time chart of an example of a ringer transmission circuit of the present invention.

FIG. 5 is a block diagram showing an example of a conventional ringer sending circuit of a subscriber circuit.

[Explanation of symbols]

 1 Telephone for subscriber 2 Ringer generator circuit 3 Subscriber circuit 4 Ringer generator 5 DC power source 6,7 Communication line 10 Ringer relay switching means 11 Ringer relay circuit 11A, 11B Relay contact of ringer relay RL1 20 Power supply and voice signal transmission / reception means 21 Power feeding / hybrid circuit 31 CODEC 40 Ringer current detection means 41 Ringer current detection circuit 51 Ring trip circuit 60 Ringer relay drive means 61 Ringer relay control circuit 71 Ringer relay drive circuit 80 Ringer current phase detection means 81 Ringer current phase detection circuit BU1 buffer C1 capacitor CO1 comparator D1 diode DL1, DL2 delay circuit FF1 flip-flop LA1 set / reset / latch circuit NA1, NA2 NAND circuit NO1 N T circuit OP1 op R1~R8 resistor RL1 Ringer Relay TR1 transistor

Claims (1)

[Claims] 1. A ringer signal generated by a ringer generation circuit (2) is sent to a subscriber telephone set (1), and the subscriber telephone set (1) and the ringer generation circuit (1) are based on the ringer signal. 2) Switching between connecting the ringer signal to the subscriber telephone (1) and the ringer current detecting means (40) for detecting the ringer current flowing between the ringer signal and the voice signal from the transmission line side. And a ring trip circuit (51) for detecting the output of the ringer current detection circuit (40) to detect an off-hook of the subscriber and sending a ringer signal stop signal. Upon receiving a ringer signal drive signal from the caller, a ringer signal stop signal, or a ringer signal stop signal from the ring trip circuit (51), the ringer relay Ringer relay control means (60) for transmitting a control signal, and the ringer relay control means (6)
0) receives the ringer relay drive signal from the ringer relay switching means (10) and the ringer relay contact (11).
In a ringer transmission circuit of a subscriber circuit of an exchange or a subscriber transmission device, which is constituted by a ringer relay drive means (70) for transmitting a ringer relay drive signal for switching A), the input from the ringer current detection means (40) A ringer current phase detection means (80) for detecting a zero-cross point of an AC signal included in the ringer signal and generating a ringer stop control clock signal having the zero-cross point as a rising point is provided, and the ringer relay drive means (70). The ringer relay control signal from the ringer relay control means (60) is used to send a ringer relay drive signal. At the rising point of the ringer stop control clock signal from the ringer current phase detection means (80), Stop sending ringer relay drive signal to restore the operation of the ringer relay Means for adding, and driving the ringer relay switching means (10) at the zero-cross point of the AC signal included in the ringer signal to stop the ringer signal of the subscriber telephone set (1). Ringer sending circuit of the person circuit.