JP3403243B2 - Network control circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network control circuit. 2. Description of the Related Art Conventionally, in a network control circuit for making a dial call by a dial pulse method, a direct current holding circuit has a dial pulse relay (hereinafter referred to as a "DP relay").
And a dial signal is transmitted by turning on and off the DP relay. FIG. 2 is a block diagram of a conventional network control circuit. In the figure, reference numeral 11 denotes a line, which can be represented by an equivalent circuit including a DC power supply 12 and resistors R1 and R2. A network control circuit 14 has terminals L1 and L2.
Is connected to the line 11. The network control circuit 1
4 is a DC cut capacitor 16 for cutting the DC component of the current from the line 11, a transformer 17, and a circuit 1 for a specific country.
9, a rectifier diode 21, a DP relay RL2, a mute relay RL3, and a DC holding circuit 23. The DC cut capacitor 16,
An AC circuit including the transformer 17 and the specific country circuit 19 and a DC circuit including the rectifier diode 21, the DP relay RL2, the mute relay RL3, and the DC holding circuit 23 are connected in parallel at points P1 and P2. The DP relay RL2 is constituted by an IC, and the DP relay RL2
The dial pulse can be generated by turning on / off the. Also, the mute relay RL3 is
C, which is turned on while the DP relay RL2 is turned on and off, and prevents the waveform of the dial pulse from being dull by a transistor (not shown), a resistor, a capacitor and the like in the DC holding circuit 23. The network control circuit 14 is connected to the terminals L1 and L2 via a pair of line capture relays RL1. The line capture relay RL1 is mechanically formed. The specific country circuit 19 is a circuit provided in a specific country, and includes, for example, a charging pulse countermeasure circuit, a drop-in level countermeasure circuit, and the like. The charging pulse countermeasure circuit is a circuit required in Germany, and attenuates a charging pulse of 16 [kHz] output from the exchange at regular intervals. On the other hand, the drop-in level countermeasure circuit is a circuit required in the Swiss standard and increases the impedance with respect to a 12 [kHz] pulse. The DC component of the current input from the line 11 to the network control circuit 14 is cut by the DC cut capacitor 16, and only the AC component is input to the AC circuit. On the other hand, the DC component flows to the DC circuit. Also, 2
6 is a line capture relay drive circuit for turning on / off the line capture relay RL1, and 28 is the DP relay RL.
Relay drive circuit for turning on / off 2 29
Is a mute relay drive circuit for turning on / off the mute relay RL3. The line capture relay drive circuit 26, DP
Relay drive circuit 28 and mute relay drive circuit 29
Are connected to ports A to C of a CPU (not shown), respectively. When a dial call is made in the network control circuit 14, the ports A to C are controlled by the software of the CPU, and the DC held by the DC holding circuit 23 is turned on and off by turning on and off the DP relay RL2. It is intermittent. FIG. 3 is a waveform diagram of a signal output to each port in the conventional network control circuit. That is, at the timing t1, the port A is set to the high level, the line capture relay drive circuit 26 (FIG. 2) is operated, and the line capture relay RL1 is turned on. Further, the signal output to the port B at the timing t2 is set to the high level,
The DP relay drive circuit 28 is operated, and the DP relay R
Turn on L2. Then, at the timing t3, the signal output to the port C is set to the high level, the mute relay drive circuit 29 is operated, and the mute relay R
Turn on L3. Subsequently, at timings t4 and t5,
The signal output to port B is set to low level for a certain period of time, and the signal output to port C is set to low level at timing t6. Thus, the timing t
4. At t5, a dial pulse can be generated by setting the signal output to the port B to a low level for a certain period of time. In this case, since the signal output to the port B is set to the low level twice, "2" is called as a dial pulse. However, in the conventional network control circuit, not only the C component of the DC cut capacitor 16 and the L component of the transformer 17 constitute a series resonance circuit, but also Specific Country Circuit 19
Has a parallel resonance circuit including an inductor and a capacitor therein, and these resonance circuits are connected in parallel to the DC circuit. Therefore, when the DP relay RL2 is turned on / off, not only a delay occurs in the rise and fall of the dial signal, but also fine vibration occurs in the dial pulse. Thus, the DP relay R
When L2 is turned on and off, the waveform of the dial pulse becomes dull, and the exchange erroneously detects the dial signal. SUMMARY OF THE INVENTION It is an object of the present invention to provide a network control circuit which solves the problems of the conventional network control circuit and does not obscure the dial pulse waveform. For this purpose, the network control circuit of the present invention is connected to a line via a line capture relay, and includes a switch relay, a DC cut capacitor,
An AC circuit including a transformer, a DC circuit connected in parallel with the AC circuit, including a rectifier diode, a DP relay, a DC holding circuit, and a mute relay;
It has a DP relay drive circuit for turning on and off a relay to generate a dial pulse, and a switch relay drive circuit for turning on and off the switch relay to interrupt the connection between the AC circuit and the line. The switch relay drive circuit receives a signal for operating a line capture relay drive circuit and a signal for operating a mute relay drive circuit.
When the line capture relay is off and the mute relay is on, the switch relay is turned off. According to the present invention, as described above, the network control circuit is connected to the line via the line capture relay, and includes an AC relay having a switching relay, a DC cut capacitor, and a transformer. A rectifying diode, a DP relay, a DC holding circuit, and a DC circuit including a mute relay, and a DP for turning on and off the DP relay to generate a dial pulse. A relay drive circuit, and a switch relay drive circuit for turning on and off the switch relay to interrupt the connection between the AC circuit and a line. The switching device relay drive circuit receives a signal for operating the line capture relay drive circuit and a signal for operating the mute relay drive circuit,
When the line capture relay is off and the mute relay is on, the switch relay is turned off. in this case,
When making a dial call, the DP relay is turned on / off by the DP relay driving circuit, and the DC held in the DC holding circuit is interrupted. In addition, since the switch relay is turned off during dialing, the AC circuit is disconnected from the line. As a result, the dial pulse is not affected by the series resonance circuit constituted by the C component of the DC cut capacitor and the L component of the transformer. Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram of a network control circuit according to an embodiment of the present invention, and FIG. 4 is a diagram illustrating an operation of a switch relay in the embodiment of the present invention. In the figure, 1
Reference numeral 1 denotes a line, which can be represented by an equivalent circuit including a DC power supply 12 and resistors R1 and R2. Reference numeral 14 denotes a network control circuit, which controls the line 1 via terminals L1 and L2.
Connected to 1. The network control circuit 14 includes a switch relay RL4, a DC cut capacitor 16 for cutting a DC component of a current from the line 11, a transformer 17, and a circuit 1 for a specific country.
9, a rectifier diode 21, a DP relay RL2, a mute relay RL3, and a DC holding circuit 23. The switching relay RL4, the DC cut capacitor 16, the transformer 17, and the circuit 1 for a specific country
9, a rectifier diode 21, a DP relay RL2, a mute relay RL3, and a DC holding circuit 23.
Are connected in parallel at points P1 and P2. The switch relay RL4, the DC cut capacitor 16, the transformer 17, and the specific country circuit 19 are connected in series in this order.
L2 and the DC holding circuit 23 are also connected in series in order, and a mute relay RL3 is connected in parallel with the DC holding circuit 23 on the DC holding circuit 23 side from the DP relay RL2. The switch relay RL4 is mechanically formed, is disposed between the point P1 and the DC cut capacitor 16, and connects and disconnects the line 11 and the AC circuit. The switch relay RL4 may be provided anywhere in the AC circuit. The DP relay RL2 is formed of an IC, and can generate a dial pulse by turning on / off the DP relay RL2. Further, the mute relay RL3 is also formed of an IC, and is turned on while the DP relay RL2 is turned on and off, thereby preventing the waveform of the dial pulse from being dull due to a transistor, a resistor, a capacitor, etc., not shown in the DC holding circuit 23. . The network control circuit 14 is connected to the terminals L1 and L2 via a pair of line capture relays RL1. The line capture relay RL1 is mechanically formed. The specific country circuit 19 is a circuit provided in a specific country, and includes, for example, a charging pulse countermeasure circuit, a drop-in level countermeasure circuit, and the like. The charging pulse countermeasure circuit is a circuit required in Germany, and attenuates a charging pulse of 16 [kHz] output from the exchange at regular intervals. On the other hand, the drop-in level countermeasure circuit is a circuit required in the Swiss standard and increases the impedance with respect to a 12 [kHz] pulse. The DC component of the current input from the line 11 to the network control circuit 14 is cut by the DC cut capacitor 16, and only the AC component is input to the AC circuit. On the other hand, the DC component flows to the DC circuit. Also, 2
6 is a line capture relay drive circuit for turning on / off the line capture relay RL1, and 28 is the DP relay RL.
Relay drive circuit for turning on / off 2 29
Is a mute relay drive circuit for turning on and off the mute relay RL3, and 31 is the switch relay RL
4 is a switching device relay drive circuit for turning on / off the switch 4. The line capture relay drive circuit 26, DP
Relay drive circuit 28 and mute relay drive circuit 29
Are connected to ports A to C of a CPU (not shown), respectively, and the switch relay drive circuit 31 is connected to ports A and C. When making a dial call in the network control circuit 14, the ports A to C are controlled by software of the CPU, and the DC held by the DC holding circuit 23 is turned on and off by turning on and off the DP relay RL2. It is intermittent. As in the conventional network control circuit 14 (see FIG. 2), as shown in FIG. 3, the port A is set to the high level at the timing t1, and the line capture relay driving circuit 26
Is activated to turn on the line capture relay RL1.
At the timing t2, the signal output to the port B is set to the high level, the DP relay drive circuit 28 is operated, and the DP relay RL2 is turned on. Then, at the timing t3, the signal output to the port C is set to the high level, the mute relay drive circuit 29 is operated, and the mute relay RL3 is turned on. Subsequently, at timings t4 and t5,
The signal output to port B is set to low level for a certain period of time, and the signal output to port C is set to low level at timing t6. Thus, the timing t
4. At t5, a dial pulse can be generated by setting the signal output to the port B to a low level for a certain period of time. In this case, since the signal output to the port B is set to the low level twice, "2" is called as a dial pulse. Here, the switch relay RL4 is connected to the switch shown in FIG.
It is operated as shown in FIG. That is, when the signal output to the port A is low level (L) and the signal output to the port C is low level, the switch relay RL4 is turned off and the signal output to the port A is high level ( When the signal output to the port C is low in H), the switch relay RL4 is turned on, and the signal output to the port A is low and the signal output to the port C is high. When the signal output to port A is at a high level and the signal output to port C is at a high level, switch relay RL4 is turned off. Therefore, since the switch relay RL4 is turned off during dialing, the AC circuit is connected to the line 11.
Disconnected from As a result, the dial pulse is affected by the specific country circuit 19 having the series resonance circuit formed by the C component of the DC cut capacitor 16 and the L component of the transformer 17 and the parallel resonance circuit formed by the inductor and the capacitor. Disappears. When the DP relay RL2 is turned on / off, the waveform of the dial pulse does not become dull, so that it is possible to prevent the exchange from erroneously detecting the dial signal. It should be noted that the present invention is not limited to the above-described embodiments, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention. As described above in detail, according to the present invention, the network control circuit is connected to the line via the line capture relay, and includes a switch relay, a DC cut capacitor, An AC circuit including a transformer, a DC circuit connected in parallel with the AC circuit, and including a rectifier diode, a DP relay, a DC holding circuit, and a mute relay;
It has a DP relay drive circuit for turning on and off the DP relay to generate a dial pulse, and a switch relay drive circuit for turning on and off the switch relay to interrupt the connection between the AC circuit and the line. The switch relay drive circuit receives a signal for operating a line capture relay drive circuit and a signal for operating a mute relay drive circuit.
When the line capture relay is off and the mute relay is on, the switch relay is turned off. in this case,
When making a dial call, the DP relay is turned on / off by the DP relay driving circuit, and the DC held in the DC holding circuit is interrupted. In addition, since the switch relay is turned off during dialing, the AC circuit is disconnected from the line. Therefore, the waveform of the dial pulse does not become dull when the DP relay is turned on / off,
It is possible to prevent the exchange from erroneously detecting the dial signal.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a network control circuit according to an embodiment of the present invention. FIG. 2 is a block diagram of a conventional network control circuit. FIG. 3 is a waveform diagram of a signal output to each port in a conventional network control circuit. FIG. 4 is a diagram showing an operation of a switch relay in the embodiment of the present invention. [Description of Signs] 11 Line 14 Network control circuit 16 DC cut capacitor 17 Transformer 21 Rectifier diode 23 DC holding circuit 28 DP relay drive circuit 31 Switch relay drive circuit RL1 Line capture relay RL2 DP relay RL3 Mute relay RL4 Switch relay

Claims (1)

(57) [Claim 1] In a network control circuit connected to a line via a line capture relay, (a) an AC including a switch relay, a DC cut capacitor, and a transformer (B) a DC circuit connected in parallel with the AC circuit and including a rectifier diode, a DP relay, a DC holding circuit, and a mute relay; and (c) turning on and off the DP relay. A DP relay drive circuit for generating a dial pulse; and (d) a switch relay drive circuit for turning on and off the switch relay to intermittently connect between the AC circuit and a line. Relay drive circuit is a line capture relay drive.
Signal to activate the drive circuit, and mute relay drive
Signal to activate the circuit
Is off and the mute relay is on,
A network control circuit for turning off a switch relay.