JPS6311823B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a call collision monitoring circuit in a network control circuit that connects to a telephone switched line, for example, a subscriber telephone network, and performs automatic outgoing calls.

A conventional circuit of this type is shown in FIG. In the figure, 1a and 1b are subscriber lines L ₁ and L ₂
and are connected to terminals 2a and 2b, respectively. In addition, the selection signal sending unit 4 has relay contacts 3a, 3
b is connected to subscriber lines 1a and 1b. 16Hz
The detection unit 5 includes diodes 6, 7, 8, 9, capacitors 10, 11, resistors 12, 13, a relay 14, and a relay contact 15. The polarity detection section 16 is composed of a diode 17, a resistor 18, a relay 19, and a relay contact 20. Reference numeral 21 denotes a control unit for performing a call collision prevention function.

Next, the operation will be explained. Among the network control functions, the automatic call function requires the timings shown in FIG. 2 a, b, and c. First, when it becomes necessary or requested to make a call, subscriber line 1
A and 1b are monitored to see if they are already receiving calls. This is because it is impossible to make a call through the subscriber line while the call is incoming, and it is necessary to respond to the incoming call. This is the so-called call collision monitoring, and is the timing at which the monitoring device monitors the polarity reversal of the subscriber line and the transmission of the 16 Hz ringing signal, which is performed by the central office exchange upon receiving a call at a fixed time Tc, as shown in FIG. 2a. Call collision monitoring timing Tc
If it is confirmed that the subscriber line is free, a selection signal can be sent, that is, the destination subscriber number can be dialed. However, prior to dialing, it is necessary to short-circuit the subscriber line with a low DC resistance value and to set the pre-pause timing Tp shown in FIG. 2b at which no selection signal is sent. After the presentation, as shown in FIG. 2c, a selection signal is sent out and a response is awaited from the other party.

The automatic call function generally works as described above, but
Of these, only the call collision monitoring will be described in detail here. Under normal conditions, relay contacts 3a, 3b,
15 and 20 are in the restored state (the state shown in the figure), so the subscriber lines 1a and 1b and the 16 Hz detection section 5 are AC-coupled by the capacitor 10. At the sending/receiving collision monitoring timing Tc, the control unit 21 connects the relay contact 2
0, and the polarity detection unit 16 is connected to the subscriber line 1a,
Connect to 1b. The DC resistance value of the polarity detection unit 16 is approximately determined by the winding resistance of the relay 19 and the resistance 18, but this resistance value is such a high resistance value that the central office exchange does not determine that the line is closed. First, the 16Hz detection section 5 operates as follows. That is, a 16 Hz calling signal sent from the central office exchange is led to diodes 6, 7, 8, and 9 by AC coupling, full-wave rectified, and applied to capacitor 11 and relay 14. Therefore, the full-wave rectified wave is smoothed by the capacitor 11, and when the voltage exceeds the voltage value of the relay 14, the relay 14 is activated, and this is detected by the control unit 21. On the other hand, the operation of the polarity detection section 16 is as follows. That is, the relay contact 20 is made, and the subscriber lines 1a,
If 1b is L ₁ (1a) side = -48V, L ₂ (1b) side = earth air, the line current is subscriber line 1b → relay contact 20 → diode 17 → relay 19 → resistor 1
8 → flows along the route of subscriber line 1a. Therefore, due to the action of the diode 17, the relay 19 operates only when the subscriber line 1b is in the earth's atmosphere, and this is detected by the control section 21. From the above, the control unit 21 controls the relays 14 and 1 at the sending/receiving collision monitoring timing Tc shown in FIG.
9 is monitored, and if there is no relay operation, it can be determined that there is no collision between incoming and outgoing calls. Thereafter, the control section 21 switches the relay contacts 3a and 3b to the selection signal sending section 4 side, performs the subsequent preparation and selection signal sending operations, and then moves to communication. In addition, relay contact 1
Reference numeral 5 designates a relay contact 3a, 3b which temporarily operates in a state where the relay contacts 3a, 3b are switched to the selection signal sending unit 4 side, and discharges the charge in the capacitor 10 via the resistor 12. In addition, the incoming call operation is 16Hz at the 16Hz detection unit 5.
Relay contacts 3a, 3b when a calling signal is detected
to respond and start communication.

Conventional call/receive collision prevention circuits are configured as described above, so two relays are required, one for detecting a 16Hz ringing signal and one for detecting polarity.In addition, a relay for polarity detection is connected to the subscriber line only when necessary. It had drawbacks such as requiring a separate relay contact for connection, requiring a large number of parts, increasing component cost and mounting space.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it is possible to reduce the number of parts by sharing the 16Hz ringing signal detection part and the polarity detection part. The purpose is to provide equipment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A call collision monitoring device according to an embodiment of the present invention will be described below with reference to the drawings. In Figure 3, the first
The same reference numerals as in the drawings indicate the same or corresponding parts, and 22 is a relay contact, 23 is a resistor, and 24 is a control section. The timing of the call collision monitoring operation in this embodiment is shown in FIGS. 4, 5, and 6. Third
The principle will first be explained based on an embodiment of the present invention with reference to the drawings. First, if we consider the state in which the relay contact 22 is activated, the diode 8 is separated from the circuit, and the subscriber lines 1a and 1b are short-circuited by the resistor 23 with a high DC resistance value, the diodes 6, 7,
It can be seen that the full wave rectification function by 8 and 9 is destroyed and the polarity of subscriber lines 1a and 1b can be determined using diodes 6 and 9, capacitor 11 and relay 14. That is, if subscriber line 1a becomes -48V, subscriber line 1b → resistor 13 → diode 9 → relay 14 → diode 6 → resistor 23 → subscriber line 1
Line current flows through path a. Yotsuteko contact point 2
2 means that the conventional 16Hz detection section 5 and polarity detection section 16 shown in FIG. 1 can be used in common. Next, a more detailed operation of this embodiment will be explained. In Figure 4, the calling/receiving collision monitoring function monitors the polarity reversal or 16Hz ringing signal associated with incoming calls on the subscriber line during the Tc period prior to the pre-pause at the time of making a call, as described above, and allows the call to be made if both are not detected. It is. The control unit 24 determines the sending/receiving collision monitoring timing Tc as shown in FIG. 4a.
The relay contact 22 is switched in the Tm ₁ period immediately after the start. Then, at the end of this timing Tm ₁ , the operating state S ₁ of the relay 14 is stored. After relay contact 22 is restored, full wave rectification is used as before.
The 16Hz call signal is monitored by whether or not the relay 14 is operating. If the control unit 24 detects the operation of the relay 14, it is determined that an incoming call is being received, and processing to that effect is performed. Figure 5a
7. The operating states of each part in this case are indicated by e. If no 16 Hz ringing signal is detected during this Tb period, the relay contact 22 is operated again and switched to the resistor 23 side during the following Tm ₂ period as shown in FIG. 4a. Then, at the end of the Tm ₂ period, the operating state signal S ₂ of the relay 14 is read, and the exclusive OR with the first operating state signal S ₁ , ie, S ₁ S _2, is determined as shown in FIG. 5d. If this logical sum S ₁ S ₂ is significant, it can be determined that the subscriber lines 1a and 1b have changed polarity and become incoming calls during call collision monitoring. FIGS. 6a to 6e show the operating states of each part in this case. In addition, the period Tm ₁
The value of Tm ₂ is determined from the sum of the operating time of the relay contact 22 and the time constant due to the capacitor 11. If you want to eliminate the delay caused by capacitor 11, connect relay contact 22 in series with capacitor 11.
Insert a break contact that works at the same timing as
It is preferable to separate the capacitor 11 from the circuit during each period of Tm ₁ and Tm ₂ .

On the other hand, the incoming call operation is the same as that shown in FIG. 1 since the relay contact 22 is restored to normal operation.

In the above embodiment, the relay contact 22 is used in common with the relay contact 15 of the conventional monitoring device, but as another embodiment of the present invention, as shown in FIG. , one side of the diode bridge circuit may be left open.
It goes without saying that the same effects as in the above embodiment can be achieved even if semiconductor elements such as photocouplers are substituted for the relays and relay contacts.

As described above, according to the sending/receiving collision monitoring circuit of the present invention, one relay and one diode bridge are used.
Since the system is structured around a combination of 16Hz detection section and polarity detection section, the number of circuit parts can be reduced, and the structure of the collision monitoring device for sending and receiving calls can be made significantly cheaper. .

[Brief explanation of the drawing]

FIG. 1 is a circuit connection diagram showing a conventional call collision monitoring device, FIG. 2 is a timing diagram related to the automatic calling operation of the device shown in FIG. 1, and FIG. 3 is a call collision monitoring device according to an embodiment of the present invention. Circuit connection diagram showing 4th
5 and 6 are timing diagrams according to this embodiment, and FIG. 7 is a circuit connection diagram of a call collision monitoring device according to another embodiment of the present invention. 1a, 1b... subscriber line, 6, 7, 8, 9...
Diode, 13, 23...Resistor, 14...Relay, 22...Relay contact, 24...Control unit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. In the call collision monitoring device of the network control circuit when connected to the telephone exchange line of the subscriber telephone network and making automatic calls, the above 16Hz ring By opening one side of the diode bridge used for signal detection and at the same time shorting the subscriber line with a resistor, a single relay can be used to detect both the 16Hz ringing signal and the polarity reversal. An incoming/outgoing collision monitoring device featuring: