JPH0226446A - Ringing signal sending control circuit - Google Patents

Abstract

PURPOSE:To prevent a trouble from occurring by providing a ringing signal period detector to detect the period of a ringing signal, predicting the time of the next zero cross point based on the detection of a zero cross point and operating the contact of a relay at that time. CONSTITUTION:A subscriber's telephone set T is connected to a switch 2 to send a ringing signal to the telephone set T or stop it, a ringing signal generator 1 and a zero cross signal detector 5 to detect the zero cross point where the voltage of the ringing signal becomes zero are connected to the switch 2. Further, a ringing signal period detector 4 to detect the period of the ringing signal is connected to a ringing signal generator 1. By providing the ringing signal period detector 4, the time of the next zero cross point base on the detection of the zero cross point is predicted and the contact of the relay is operated at that time. Thus, the trouble is prevented from occurring.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a call signal sending control circuit for an exchange.

[Conventional technology]

As a first example, the conventional calling signal sending control circuit has a second calling signal sending control circuit.
There is a configuration as shown in the figure. The subscriber's telephone T is connected to the ringing signal generator 11 via the contact 12a of the relay.
It is connected to the. The ringing signal (16 to 66 Hz) generated by the ringing signal generator 11 is interrupted by the operation and restoration of the relay 12, and is sent to the telephone T. A control signal for operating and restoring the electric appliance 12 is given to a calling signal control signal generator 13 in terms of software. When the signal control signal generator 13 receives this signal, it sends this signal to a holding circuit 17 that has a function of holding the input state. The holding circuit 17 continues to hold the operating or restoring state until the next signal is received, and at the same time sends a control signal for controlling the driving state to the driving circuit 18 that drives the relay 12. The drive circuit 18 drives the relay 12 according to this control signal, and sends out the ringing signal to the telephone T intermittently. In this case, there is no temporal correlation between the operation/recovery of the relay 12 and the ringing signal, so the relay 12 operates or recovers to turn on or cut off the current of the ringing signal. There are cases where this happens. This is contact 12 of the relay.
In step a, a large current is switched on and off, which can cause trouble. Therefore, a spark quencher SK is usually used, which is constructed by connecting a capacitor Ck and a resistor Rk in series to protect the relay contact 12a.

Furthermore, as an improved version of the above-mentioned paging signal sending control circuit, there is a structure shown in FIG. In order to avoid turning on or cutting off the current of the ringing signal when the relay 12 is activated or restored, the zero-crossing signal detector 15 detects the zero-crossing point at which the voltage of the ringing signal becomes zero. The output and the output of the calling signal control signal generator 13 are input to the holding circuit 17, and the relay 12 is connected at the zero cross point.
A control signal is sent to the drive circuit 18 that controls the drive state. The drive circuit 18 drives the relay 12 in accordance with this control signal and intermittents the ringing signal to connect the telephone II.
This is what is sent to T.

[Problem to be solved by the invention]

In the conventional ringing signal sending control circuit described above, as shown in Figure 2, the ringing signal current may be turned on or off at the relay contacts, so a spark quencher is used. Therefore, the capacitor used in the spark quencher is required to have a high withstand voltage, and the circuit configuration becomes large. In addition, if it is shown in Fig. 3, there is no need to use a spark quencher, but in an actual circuit, the relay operation delay is several milliseconds, so the relay 12 is driven at the zero cross point with a 66Hz ringing signal. However, there is a problem that the circuit is opened and closed near the peak value of the ringing signal, so it is ineffective.

An object of the present invention is to provide a ringing signal period detector that detects the period of a ringing signal, so that when a zero-crossing point is detected, the time of the next zero-crossing point is predicted based on the detected zero-crossing point, and the relay contacts are operated at that time. It is an object of the present invention to provide a calling signal sending control circuit which prevents the occurrence of failures by causing the above problems to occur.

[Means to solve the problem]

The ringing signal sending control circuit of the present invention includes a ringing signal generator that generates a ringing signal to notify a subscriber's telephone set connected to an exchange of an incoming call, and a ringing signal generator that sends or stops the ringing signal to the telephone set. a switch; a ringing signal control signal generator that generates a signal for controlling sending or stopping of the ringing signal;
a ringing signal period detector for detecting a period of the ringing signal generated by the ringing signal generator; a zero-crossing signal detector for detecting a zero-crossing point at which the voltage of the ringing signal becomes zero; and a ringing signal period. a holding control signal generator that sends out a set/reset signal for controlling the switch to operate in synchronization with the detection output of the detector and with a fixed time delay from the detection output of the zero-crossing signal detector; and the call signal. a holding circuit that sets the operating state of the switch based on the output of the control signal generator and the output of the holding control signal generator and holds that state; and a holding circuit that drives the switch in response to the holding state of the holding circuit and controls the ringing. This configuration includes a drive circuit for sending or stopping signals.

[Example] Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

The subscriber's telephone T is connected to a switch 2 for sending or stopping a ringing signal to the telephone T. Also connected to the switch 2 are a ringing signal generator 1 that generates a ringing signal, and a zero-crossing signal detector 5 that detects a zero-crossing point, which is the point in time when the voltage of the ringing signal becomes zero. Furthermore, the calling signal generator 1
A ringing signal period detector 4 is connected to detect the period of the ringing signal. The outputs of the ringing signal period detector 4 and the zero crossing signal detector 5 are connected to a hold control signal generator 6 which sends out set/reset signals for controlling the operation of the switch 2. The output of the ringing signal control signal generator 3, which generates a signal for controlling sending or stopping of the ringing signal, and the output of the holding control signal generator 6 are connected to a holding circuit that sets the operating state of the switch and maintains that state. 7 is connected.

The output of the holding circuit 7 is connected to a drive circuit 8 for driving the switch 2 and sending or stopping the ringing signal.

Next, the operation will be explained.

When a request is made to send a ringing signal due to the connection operation of the exchange, the output of the ringing signal control signal generator 3 becomes "high."If the ringing signal generator 1 is in operation, the ringing signal period detector always outputs a "high" signal. 4 and zero cross signal detector 5
The control signal generator 6 performs a detection operation and holds the result.
It is being sent to

The holding control signal generator 6 receives these signals and is synchronized with the detection output of the ringing signal period detector 4 and delayed by a certain period of time from the detection output of the zero-crossing signal detector 5.
Set/reset signals for control are sent out in consideration of the operation delay of switch 2 so that switch 2 is operated at the time predicted to be the next zero-crossing point. The holding circuit 7 receives this set/reset signal and the fact that the output of the calling signal control signal generator 3 becomes "high",
A signal for driving the switch 2 is sent to the drive circuit 8.

The holding circuit 7 continues this state until the next change occurs, that is, the output of the ring signal control signal generator 3 becomes "low" and the output of the holding control signal generator 6 is received. This operation continues until the output of the ring signal control signal generator 3 remains "low".

By the above operation, the switch 2 can be opened and closed at the zero cross point.

〔Effect of the invention〕

As explained above, the present invention provides a ringing signal period detector that detects the period of the ringing signal, so that when a zero-crossing point is detected, the time of the next zero-crossing point is predicted based on it, and the relay is activated at that time. This has the effect of preventing the occurrence of failures by operating the contacts.

It is a diagram.

1.11...Call signal generator, 2...
・Switch, 3.13... Calling signal control signal generator, 4... Ringing signal period detector, 5
, 15... Zero cross signal detector, 6...
...Holding control signal generator, 7.17...Holding circuit, 8, 18... Drive circuit, 12...
Relay, 12a...Relay contact, SK...
... Spark quencher, T ... Subscriber's telephone.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of a conventional calling signal sending control circuit, and FIG. 3 is a block diagram of a conventional calling signal sending control circuit! 3 M3 figure

Claims (1)

[Claims] a ringing signal generator that generates a ringing signal to notify a subscriber's telephone connected to an exchange of an incoming call; a switch that transmits or stops the ringing signal to the telephone; and a switch that transmits or stops the ringing signal. a ringing signal control signal generator that generates a signal for controlling the ringing signal; a ringing signal period detector that detects the period of the ringing signal generated by the ringing signal generator; and a point in time when the voltage of the ringing signal becomes zero. a zero-crossing signal detector for detecting a zero-crossing point,
a holding control signal generator that sends out a set/reset signal for controlling the switch to operate in synchronization with the detection output of the ringing signal period detector and with a fixed time delay from the detection output of the zero-crossing signal detector; ,
a holding circuit that sets the operating state of the switch based on the output of the calling signal control signal generator and the output of the holding control signal generator and holds the operating state; and a holding circuit that drives the switch in response to the holding state of the holding circuit. and a drive circuit for sending or stopping the ringing signal.