JPS6332307B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to telephone off-hook detection when sending a ringing signal.

In particular, as the communication path from the exchange to the telephone becomes long, there is a method of detecting a loop by balancing the AB lines of the communication path in order to reduce the influence of noise due to induced vertical voltage.

However, in a general subscriber circuit, when detecting a subscriber's loop, that is, detecting off-hook, AB
Earth air is applied to one of the wires, and the other wire is connected to a battery via a detection relay, allowing unbalanced loop detection.

Therefore, as mentioned above, as communication routes become longer distances, a line circuit trunk, which balances AB lines and detects loops, is installed near the subscriber circuit and the subscriber circuit in the middle of the communication route. It is provided.
FIG. 1 shows an example of this.

In the figure, when you go off-hook on the phone side,
A communication current supply/loop monitoring relay J provided in parallel with the AB line operates, and its contact _j1 causes relay B to operate.

Therefore, contact j ₂ of relay J and contact of relay B
The operation of b ⁰ , b ¹ , and b ² forms a DC loop between terminals A ₀ and B ₀ .

A subscriber circuit (not shown) detects this DC loop and performs a known call detection process.

In this way, the direct current is interrupted by the relay loop REP, and the direct current loop on the telephone side is relayed by relay J.

On the other hand, if this telephone is used by the called party, a ringer trunk (not shown) will send a message that continues for 1 second and then stops for 2 seconds.
A 16Hz ringing signal is sent through the subscriber circuit.

If this ringing signal passes through the relay ring REP and is sent directly to the telephone side, relay J will malfunction, so the ringing signal is temporarily sent to the receiving relay R installed in the diode bridge formed by D ₀ to _{D 3} . receive,
A calling signal is sent to the telephone via contacts r ₁ and r ₂ of the receiving relay R.

That is, RG is a 16Hz calling signal source and continuously generates a signal. On the other hand, the receiving relay R operates during the presence of a ringing signal sent from the exchange. In other words, during the 2 second pause, it is in the recovery state, and 1
It is active only during the duration of seconds.

Then, only when relay R is operating, its contacts r1 and r2
operates, and the ringing signal from the ringing signal source RG is transmitted to the telephone set.

Therefore, the telephone bell rings for 1 second and pauses for 2 seconds. The fact that the telephone has gone off-hook is detected by relay J when relay R is restored.

That is, when the telephone goes off-hook, relay J operates, and similarly to the above-described call detection, relay B operates to form a DC loop between terminals A ₀ and B ₀ .

This DC loop is detected by a ring trip relay provided in a ringer trunk (not shown), the ringing signal is stopped, and the next control is started.

FIG. 2 shows the operation timing chart of FIG. 1, in which the same reference numerals as in FIG. 1 indicate operating states.

That is, a ringing signal (indicated by a broken line in the figure) is sent to the telephone only when relay R is in operation.

Even if the telephone goes off-hook at, for example, time _t1 while this calling signal is being sent out, relay J will not operate immediately, but will operate after relay R is restored once.

Then, as relay J operates, relay B operates, and as described above, the process moves to the next exchange process. However, the problem here is that the delay time between when the telephone goes off-hook and when relay J operates is wasted, and if the telephone goes off-hook while the telephone is sending out a ringing signal, a "rasping" sound from the ringing signal can be heard through the telephone receiver. , which causes discomfort to subscribers.

Therefore, the present invention improves the above drawbacks, and is designed to receive a calling signal through a contact that is made in accordance with the operation of a receiving relay for a calling signal in a line circuit trunk provided between a telephone set and a subscriber circuit. Only when the relay ring installed in the line circuit trunk is bypassed, the telephone side line is extended to the subscriber circuit side, and a ringing signal is sent to the telephone from the ringer trunk installed on the subscriber circuit side. This is a line circuit trunk in a telephone exchange.

The present invention will be explained in more detail below with reference to the drawings.

FIG. 3 shows an embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same functions.

Here, the difference from FIG. 1 is the operation when receiving a calling signal, and this will be mainly explained.

When the ringer trunk RGT is connected, the S relay (not shown) of the trunk is operated by the central control device (not shown), and its contacts s1 and s2
closes.

On the other hand, a ringing signal that lasts for 1 second and stops for 2 seconds is the signal source
It is repeatedly sent from IRG, and this signal is sent to line circuit trunk LCT via network NW and subscriber circuit LRG.

Therefore, the receiving relay R operates only during the existence period of this calling signal, that is, for one second. These operations are the same as in the conventional example shown in FIG. 1, but when this receiving relay R operates, its contacts r ₁ and r ₂ operate, and a calling signal is sent directly to the telephone.

At this time, when the telephone goes off-hook, the ring trip relay RT in the ringer trunk RGT operates. The operation of this relay RT is monitored by a central control device (not shown), and when the operation of the relay RT is detected, the S relay (not shown) is restored. Thereupon, the sending of the calling signal is also stopped, and the receiving relay R is restored.

When receiving relay R is restored, its contacts r ₁ and r ₂ are also restored, relay J is activated by the off-hook state of the telephone, that is, by the telephone side loop, and relay B is also activated by its contact j1. In this state, it is possible to make a call, and when the call ends, each relay is restored.

Although the operation time chart in Fig. 3 is shown,
FIG. 4 shows operating states with the same reference numerals as in FIG. 3; In other words, if the telephone goes off-hook at time t1 while sending a ringing signal to the telephone, the ringer trunk
RGT detects this, and when the ringing signal disappears, relay B is restored, relay J is activated, and then relay B is activated.

Therefore, even if the telephone goes off-hook while sending a ringing signal, it is immediately detected, there is almost no processing delay in the switching system, and the ringing signal is immediately stopped, so that the called telephone subscriber does not experience unpleasant noises. There will be no more giving.

Also, during the ringing signal pause period, receiving relay R is inactive, but off-hook of the telephone is detected by relay J, relay B is also activated, and a DC loop is formed between terminals A ₀ and B ₀ , so that the ringer trunk is Detect this with RGT's ring trip relay RT.

As described above, the present invention has extremely excellent effects, since there is almost no processing delay as an exchange, and no unpleasant sound is given to the called telephone subscriber when he or she responds.

[Brief explanation of the drawing]

FIG. 1 shows a conventional example, FIG. 2 shows an operation time chart of FIG. 1, FIG. 3 shows an embodiment of the present invention, and FIG. 4 shows an operation time chart of FIG. 3. In the figure, LCT is a line circuit trunk, LRG is a subscriber circuit, J is a call current supply and loop monitoring relay, R is a ring signal reception relay, REP is a relay ring, RGT is a ringer trunk, and RT is a ring trip relay. It is.

Claims (1)

[Claims] 1. In a line circuit trunk installed between a telephone set and a subscriber's circuit, a relay ring installed in the line circuit trunk only when a calling signal is received through a contact that is made in conjunction with the operation of a receiving relay for the calling signal. A line circuit trunk in a telephone exchange, characterized in that the line on the telephone side is extended to the subscriber circuit side, and a ringer trunk provided on the subscriber circuit side sends a ringing signal to the telephone set.