JP2585360B2 - Ring trip method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ring trip method for detecting a called party response when a calling signal is transmitted in a subscriber circuit of a telephone exchange having a ground fault / touch switch detection circuit, and in particular, to a ring trip method. The present invention relates to a ring trip device suitable for detecting a called party's response by also using a ground fault / contact detection circuit.

[Prior Art] As a ring trip means for detecting a called party response when a calling signal is transmitted in a subscriber circuit of a conventional telephone exchange, a digital switching system supervised by Masato Chiba, edited by the Institute of Electronics and Communication Engineers, March 1986 A dedicated response detection circuit (ring trip circuit) is provided as described on pages 77 to 83 of the publication. This ring trip circuit is composed of many elements as described in JP-A-59-221146 and JP-A-59-231960. Further, as a circuit for detecting a ground fault / contact in a subscriber circuit of a telephone exchange, a ground fault / contact detection circuit having a configuration as described in JP-A-61-62268 and JP-A-57-37967 has been devised. ing.

[Problems to be solved by the invention]

The above prior art has a problem that a dedicated ring trip circuit composed of many elements is required as a means for detecting a called party response when a calling signal is transmitted from a subscriber circuit of a telephone exchange.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a ring trip device which is used as a ground fault / contact contact detection circuit and which can reduce the cost of a subscriber circuit by eliminating the use of a dedicated ring trip circuit for the subscriber circuit of a telephone exchange.

[Means for solving the problem]

An object of the present invention is to provide a subscriber circuit of a telephone exchange having a ground fault / contact detection circuit, in which a ground fault / contact detection circuit is connected to only one of the communication lines when the called party answers when a call signal is transmitted. This is achieved by a ring trip method that detects a called party response by passing a detectable current through the touch detection circuit.

[Action]

In the ring trip method described above, a general ground fault / cross-contact detection circuit detects the current flowing through the two communication lines A and B, and compares the A line current with the B line current to determine the difference current. When the value exceeds a preset value, the output is significant (detection state). Therefore, when the called party answers when the calling signal is transmitted, only the one ground line of the ground fault / contact detection circuit is connected to the ground. By passing a sufficient current to make the output of the short-circuit / short-circuit detection circuit meaningful, the response of the called party at the time of transmitting the calling signal can be detected (ring trip) by also using the short-circuit / short-circuit detection circuit. This eliminates the need for a dedicated ring trip circuit.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram showing an embodiment of a ring trip device which also serves as a ground fault / cross contact detection circuit of a subscriber circuit according to the present invention. In FIG. 1, 1 is a ground fault / contact detection circuit, 2 is an A-line current detection circuit, 3 is a B-line current detection circuit,
Is a comparison circuit, 5 is a ground fault / contact detection circuit output, 6 is a call current supply circuit, 7 is a call signal transmission signal input, 8 is a ground fault / contact detection / ring trip identification circuit, 9 is a ground fault / contact detection output. , 10 is ring trip output, TEL is subscriber terminal, A
Is a battery line side terminal, B is a ground line side terminal, r _g is a call signal transmission relay contact, R _RG is a resistor, CR is a call signal source, and V _BB and V _RG are power supplies. In FIG. 1, parts not directly related to the present invention are omitted.

Ground-incompatible detecting circuit 1 of the subscriber circuit of Figure 1 is the A line current detection circuit 2 for detecting the A line current I _A, and B line current detecting circuit 3 for detecting the B line current I _B, A line current detecting circuit 2 and the B line current detecting circuit 3 and the output of the reference current difference current between I _RF and compares the a line current I _a and B line current I _B | I _a -I _B | reference current I _RF And a comparison circuit 4 which makes the ground fault / contact detection output 5 meaningful (detection state) when it exceeds. The ground fault / contact detection circuit output 5 is connected to a ground fault / contact detection / ring trip identification circuit 8. The battery V _BB line side of the call current detection circuit 6 is connected to one end of an A-line current detection circuit 2 in the ground fault / cross-contact detection circuit 1, and the other end of the A-line current detection circuit 2 is a relay contact r for calling signal transmission. Connect to the battery line side terminal A via _g . The ground wire side of the call current supply circuit 6
It is connected to the ground line side terminal B via the B line current detection circuit 3 in the touch detection circuit 1. Between the battery line side terminal A ground line side terminal B is connected to the subscriber terminal TEL, the make of the call signaling relay contact r _g is through a resistor R _RG and ringing signal source CR and power V _RG Grounded. The ground fault / contact detection / ring trip identification circuit 8 has a call signal transmission signal input 7, a ground fault / contact detection output 9, and a ring trip output 10.

In the above configuration, ground-incompatible detecting circuit 1 detects the A line current I _A with A line current detection circuit 2, and B line current detecting circuit 3 detects the B line current I _B, the detection result by sending to the comparison circuit 4, the differential current of the a line current I _a and B line current I _B in the comparator circuit 4 | is compared with a preset reference current I _RF, | I _a -I _B The result of this comparison is | I _A −I _B |> I _RF
In this case, the ground fault / contact detection circuit output 5 is significant (detection state). The ground fault / contact detection / ring trip identification circuit 8 is based on the ground fault / contact detection circuit output 5 and the call signal transmission signal input 7 so that the ground fault / contact detection circuit output 5 is significant and the call signal is transmitted. When the signal input 7 is meaningless, the ground fault / contact detection output 9 is made significant, and
When the contact detection circuit output 5 is meaningful and the call signal transmission signal input 7 is meaningful, the ring trip output is operated to be meaningful, so that the ground fault / contact detection circuit output 5 becomes meaningful. At times, it is determined whether a ground fault / contact has been detected or a ring trip has occurred.

FIG. 2 is an explanatory diagram showing signal waveforms of the respective units at the time of detecting a ground fault / cross-contact in FIG. 2, the same reference numerals as those in FIG. 1 denote the signal waveforms of the same parts. First, the operation in the case where an abnormality such as a ground fault or a contact fault in FIG. 1 has occurred will be described with reference to FIG. The battery wire A of FIG. 1 is grounded or the ground wire B
If an abnormality such as line contact occurs, the A-line current
I _A and B line current I _B and a different value, and therefore the second view of the differential current waveform | I _A -I _B | are shown as the difference current | I _A -I _B | a reference current I _RF At this point, the output 5 of the ground fault / contact detection circuit becomes meaningless and meaningless as shown in the output waveform 5 of the ground fault / contact detection circuit in FIG. At this time, since the calling signal has not been sent, the calling signal sending signal input 7 is meaningless as shown in the calling signal sending signal input waveform 7 in FIG. Therefore, as shown in the ground fault / contact detection output waveform 9 in FIG.
The ground fault / contact detection output 9 is meaningless from meaningless, and an abnormality such as ground fault / touch is detected. Also, since the ringing signal transmission signal input 7 is meaningless, the ring trip output 10 remains meaningless as shown in the ring trip output waveform 10 of FIG. If there is no abnormality such as ground fault or contact,
A line current I _A and B line current I _B and the approximately equal a second difference current waveform as shown in FIG. _{| I A -I B | ≒ 0} < since the I _RF, ground-incompatible detection circuit output waveform 5 is not meaningful, so the ground fault / contact detection output waveform 9 is also the ring trip output waveform 10.
Also makes no sense.

FIG. 3 is an explanatory diagram showing signal waveforms of respective parts when the called party answers during transmission of the calling signal of FIG. In FIG. 3, the first
The same reference numerals as those in the drawings indicate signal waveforms of the same portions. Then the first
The operation in the case where there is a called party response during transmission of the calling signal shown in the figure will be described with reference to FIG. Figure 1 call the signal transmission request is call signaling relay contact r _g operates the ground - Power V _RG - ringing signal source CR- resistor R _RG - subscriber terminal TEL (bell circuit) -B line By forming an AC closed circuit of a current detection circuit 3-communication current supply circuit 6-ground, the subscriber terminal TE
The bell circuit in L rings. In this state, no DC current flows and an AC current flows through the bell circuit of the subscriber terminal TEL. The A line current detection circuit 2 when the have been disconnected call signal sending relay contact r _g is the battery line side terminal A for operating conditions, A line current I _A is zero. Therefore, the A-line current
Differential current I _A and B line current I _B | I _A -I _B | difference current waveform of FIG. 3
| I _A -I _B | is as shown in, the maximum value I _R and the reference current I _RF of the current call signal being sent during the on-hook if as a I _R <I _RF, land of Figure 3 The ground fault / contact detection circuit output 5 becomes meaningless as shown in the output waveform 5 of the ground fault / contact detection circuit, and therefore, as shown in the ring trip output waveform 10 of FIG. The ring trip output 10 is meaningless. Then, when the called party answers (off-hook the subscriber terminal TEL),
Ground-Power supply V _RG -Call signal source CR-Resistance R _RG -Subscriber terminal TE
By forming an L (DC loop circuit) -B line current detection circuit 3-communication current supply circuit 6-grounded DC closed circuit, a sum current _ITR of AC current and DC current flows. Thus A line current I _A and B line current I differential current _{B | I A -I B | I} A -I B | | difference current waveform of Figure 3 is to change as shown in, when the off-hook When the difference current waveform | I _A −I _B | exceeds the reference current I _RF , the ground fault / contact detection circuit output 5 becomes significant as shown in the ground fault / contact detection circuit output waveform 5 in FIG. .
At this time, the ringing signal transmission signal input 7 is significant as shown in the ringing signal transmission signal input waveform 7 in FIG. Ring trip output waveform 10 in Fig. 3
As shown in (1), the called party response is detected (ring trip). At this time, the ground fault / contact detection output 9 has no meaning as shown in the calling signal sending signal input waveform 7 in FIG. 3 because the calling signal sending signal input 7 is significant.

In the above embodiment, as a means for determining whether the output of the ground fault / contact detection circuit 1 is significant due to the detection of the ground fault / contact, or whether it is significant by a ring trip, a ground fault / contact detection / ring Trip identification circuit 8
However, when the output of the ground fault / contact detection circuit becomes significant during the sending of the calling signal, a ring trip is performed. When it is significant, it may be determined that a ground fault or touching has been detected, so that it can be easily realized by software.

As described above, according to the present embodiment, the ground fault of the subscriber circuit
The means for separating the ground fault / contact contact and the ring trip by using the contact touch detection circuit as well can detect the original ground fault / contact contact and also detect the called party response (ring trip) when the calling signal is transmitted. Therefore, the ring trip circuit provided exclusively for the purpose of the conventional ring trip can be eliminated.

〔The invention's effect〕

According to the present invention, a ring trip can be performed by also using a ground fault / contact touch detection circuit of a subscriber circuit. This has the effect of making the user circuit economical.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a ring trip device according to the present invention, FIG. 2 is a signal waveform diagram of each part at the time of detection of a ground fault / cross contact shown in FIG. 1, and FIG. It is a signal waveform diagram of each part at the time of a user response. 1 ... ground fault / contact detection circuit 2 ... A-line current detection circuit
3 B-line current detection circuit 4 Comparison circuit 5 Ground / contact detection circuit output 6 Communication current supply circuit 7
Call signal transmission signal input, 8: Ground fault / contact detection / ring trip identification circuit, 9: Ground fault / contact detection output, 10 ...
Ring trip output, TEL ...... subscriber terminal, r _g ...... call signaling relay contacts, R _RG ...... resistance, CR ...... ringing signal source, V _BB, V _RG ...... Power

Claims (1)

(57) [Claims] 1. An A-line current detection circuit for detecting a battery line current of a subscriber line, a B-line current detection circuit for detecting a ground wire current, an output of the A-line current detection circuit, and a B-line current detection. Ground fault / contact detection circuit consisting of a comparison circuit that detects the difference between the current on the battery line and the current on the earth line of the subscriber line based on the circuit output and outputs the result of comparison with a preset threshold value In the subscriber circuit, the battery line side of the subscriber circuit is connected to the battery line side of the communication current supply circuit, the A-line current detection circuit of the ground fault / contact detection circuit, and the battery of the subscriber line via the call signal transmission switch. The ground wire side of the subscriber circuit is connected to the ground wire side of the call current supply circuit, and the ground wire of the subscriber line via the B wire current detection circuit of the ground fault / contact detection circuit,
When the call signal is transmitted, the switch for transmitting the call signal is operated to disconnect the connection between the subscriber line on the battery line side and the A-line current detection circuit, and the call signal is transmitted from the battery line of the subscriber line to the subscriber terminal, the earth wire. Through the B-line current detection circuit, and when the called party answers, a DC loop is formed by the subscriber terminal, so that a DC current component is superimposed and flows through the ground fault / contact detection circuit. A ring trip device, wherein a ground fault / contact detection circuit outputs a detection output, thereby detecting a called party response.