JPH03250951A - Ring trip method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Summary) A digital exchange monitors the current of a calling signal that calls a subscriber, and when the DC current exceeds a predetermined threshold, it is determined that the subscriber is off-hook, and the DC current Regarding the ring trip method that prevents malfunction of the ring trip circuit that outputs an off-hook detection signal while the off-hook detection signal is exceeded, when the ring signal is sent out, an inrush current flows into the capacitor C of the bell circuit, the voltage rises, and the voltage exceeds the threshold. The present invention also aims to provide a ring trip method that does not detect off-hook, and is configured to include validity/invalidity determining means that does not detect off-hook if the off-hook detection signal does not continue for a predetermined period of time at a subsequent stage of the ring trip circuit.

[Industrial application field]

The present invention monitors the current of a calling signal that calls a subscriber in a digital exchange, and when the DC current exceeds a predetermined threshold value, it is determined that the subscriber is off-hook, and the DC current exceeds the threshold value. The present invention relates to a ring trip method that prevents malfunction of a ring trip circuit that outputs an off-hook detection signal during a period of time.

[Conventional technology]

FIG. 4 is a block diagram of a conventional call control section.

In FIG. 4, the exchange common unit 15 sends an incoming call control signal to the line control circuit 14 when a call is received from a subscriber.

Then, the line control circuit 14 sends a signal to the relay driver 16 to connect and disconnect the line relay contact 11, and the line relay contact 11 is set to 1. Solid line side 2
For example, 20
Hz signal is intermittent, and a calling signal as shown in (A) is sent to the main part 10 of the subscriber, including capacitor C, choke L, and resistor R1.
The signal is sent to the bell circuit consisting of the following to ring the bell.

When the subscriber takes the telephone off-hook during a call, the switch 18 is turned on, and when the line relay contact 11 is on the dotted line side and a DC current flows from the ground to -48V, as shown in (B), the voltage across the resistor R3 is The voltage increases and this voltage is input to the ring trip circuit 1.

When this voltage becomes larger than the threshold value as shown in (B), the ring trip circuit 1 sends a detection signal to the concentrator circuit 13 as an off-hook detection while the voltage increases.

On the other hand, when the line relay contact 11 is on the solid line side, the loop monitoring circuit 12 detects off-hook and sends a detection signal to the line concentrator circuit 13.

The line concentrator 13 sends an off-hook detection signal to the line control circuit 14 in response to any input.

Then, the line control circuit 14 stops the connection and disconnection of the line relay contact 11 by the relay driver 16, makes it a solid line, and notifies the exchange common section 15 that off-hook has been detected.

Then, the exchange common unit 15 recognizes the off-hook state, notifies the line control circuit 14 that the call state has ended, and ends the call state.

[Problem to be solved by the invention]

However, when the line relay contact 11 first turns to the dotted line side when a calling signal is sent out, an inrush current as shown in Fig. 4(C) flows through the capacitor C of the bell circuit, and the voltage across the resistor R3 rises. .

A voltage difference occurs across the resistor R3, a direct current flows, and (
As shown in C), when the threshold is exceeded, the ring trip circuit l
The concentrator circuit 13 sends a pseudo off-hook detection signal while the threshold is erroneously exceeded even though the phone is not off-hook.
There is a problem in that the line control circuit 14 is notified of the call signal via the call signal, and the transmission of the call signal is stopped.

An object of the present invention is to provide a ring trip method that does not detect off-hook even when a rush current flows through the capacitor C of the bell circuit and the voltage rises and exceeds a threshold value when a ringing signal is sent.

(Means for solving problems) FIG. 1 is a block diagram of the principle of the present invention.

As shown in Figure 1, the digital exchange monitors the current of the calling signal that calls the subscriber, and when the DC current exceeds a predetermined threshold, it is determined that the subscriber is off-hook, and the DC current exceeds the threshold. A validity/invalidity determining means 2 which does not detect off-hook if the off-hook detection signal does not continue for a predetermined period of time is provided at a subsequent stage of the ring trip circuit 1 which outputs an off-hook detection signal while the off-hook detection signal is exceeded.

[For production]

According to the present invention, when a ringing signal is sent, a rush current flows through the capacitor C of the bell circuit, the voltage rises and exceeds the threshold value, and while the threshold value of the ring trip circuit 1 is exceeded, a pseudo off-hook detection signal is output, and the subsequent stage Even if input to the validity/invalidity determination means 2, this output period is shorter than the period for normally detecting off-hook and outputting an off-hook detection signal, and in the latter stage validity/invalidity determination means 2, this output period is shorter than the period for outputting a normal off-hook detection signal. Since the predetermined time is a slightly short period, this pseudo off-hook detection signal is invalidated.

Therefore, the transmission of the paging signal will not be stopped due to the pseudo off-hook detection signal.

〔Example〕

FIG. 2 is a block diagram of a call control unit according to an embodiment of the present invention;
FIG. 3 is a block diagram of the validity determining circuit according to the embodiment of the present invention, showing the validity determining circuit 2 and the portion of the line control circuit 14 that transmits or stops the incoming call control signal.

The difference between FIG. 2 and the conventional example shown in FIG. 4 is that the validity/invalidity determination circuit 2, detailed in FIG. do.

Off-hook detection signals from the ring trip circuit 1 and the loop monitoring circuit 12 are input to the validity/invalidity determination circuit 2 in FIG. 2 via the line concentrator 13.

When a ringing signal is sent out, a rush current flows through the capacitor C of the bell circuit, and in the ring trip circuit 1, as shown in Fig. 3 (A) (B).
When the portion exceeding the threshold outputs a Lebel pseudo off-hook detection signal as shown in FIG.

Flip-flop (hereinafter referred to as FF) 20.2 in Figure 3
As shown in FIG. 3(C), the period of the clock CLK1 to 1 is longer than the time when the inrush current exceeds the threshold value, and shorter than the time when the inrush current exceeds the threshold value in the case of normal off-hook. Clock CL like a signal
Even if a rubel with a period shorter than the period of K1 is input, FF2
0°FF21. The output of the NAND circuit 22 of the validity/invalidity determination circuit 2 consisting of the NAND circuit 22 is a level, which is the same as when no off-hook detection signal is input.

Of course, if the normal off-hook signal of Lebel is input for a period longer than the period of the clock CLKI, the output of the NAND circuit 22 becomes O level.

The incoming call control signal inputted from the exchange common section 15 to the line control circuit 14 is a level when a call is received from a subscriber, and a level of 0 when there is no call.
level, and is input to the AND circuit 24 in FIG.

If the output of the NAND circuit 22 is now LeHel, the output of the FF 23 is LeBel, and the incoming call control signal is sent to the relay driver 16 via the FF 25 to connect and disconnect the line relay contact 11.

When off-hook is detected and the output of the NAND circuit 22 becomes 0 level, the FF 23 is cleared and the output becomes 0 level, so the incoming call control signal is not output from the AND circuit 24 and the sending of the calling signal is stopped.

Here, even if the pseudo off-hook detection signal is inputted from the ring trip circuit 1 via the line concentrator 13 while the ringing signal is being sent, the output of the NAND circuit 22 of the validity/invalidity determination circuit 2 is level, so the incoming call control signal is is not blocked by the AND circuit 24 and does not stop sending out the calling signal.

That is, even if a pseudo off-hook detection signal is output from the ring trip circuit 1 due to a rush current to the capacitor C of the bell circuit, it will not be mistakenly determined as an off-hook detection and the transmission of the ringing signal will not be stopped.

Note that the clock CLK2 in FIG. 3 is a phase control signal that is a clock having the frequency of the calling signal.

Furthermore, even if the validity/invalidity determination circuit 2 is inserted after the ring trip circuit 1, the same effect can be obtained.

[Effects of the Invention] As described in detail above, according to the present invention, even if a pseudo off-hook detection signal is output from the ring trip circuit 1 due to a rush current to the capacitor C of the bell circuit when a ringing signal is sent out, an off-hook error occurs. This has the effect of eliminating the need to detect and stop the transmission of the calling signal.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a block diagram of a call control unit according to an embodiment of the present invention, FIG. 3 is a block diagram of a validity/invalidity determination circuit according to an embodiment of the present invention, and FIG. 4 is a block diagram of a validity determining circuit according to an embodiment of the present invention. FIG. 2 is a block diagram of a conventional call control unit. In the figure, 1 is a ring trip circuit, 2 is a valid/invalid judgment means, a valid/invalid judgment circuit, 10 is a main part of the subscriber ← path, 11 is a line relay contact, 12 is a loop monitoring circuit, 13 is a concentrator circuit, 14 is a Line control circuit, 15 is a common part of the exchange, 16 is a relay driver, 17 is a signal device, 18 is a switch, 20.21, 23.25 are flip-flops, 22 is a NAND circuit, 24 is an AND circuit, C is a capacitor, L indicates choke, and R1-R3 indicates resistance. Tumor block diagram of the present invention

Claims (1)

[Claims] The digital exchange monitors the current of the calling signal that calls the subscriber, and when the DC current exceeds a predetermined threshold, it is determined that the subscriber is off-hook, and while the DC current exceeds the threshold, an off-hook detection signal is sent. A ring trip method characterized in that a validity/invalidity determining means (2) which does not detect off-hook if an off-hook detection signal does not continue for a predetermined period of time is provided at a subsequent stage of a ring trip circuit (1) that outputs a ring trip circuit.