JP2997560B2 - Network controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

 [Object of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network controller connected to a subscriber telephone line and activated by a no-ringing call signal from the telephone line.

[0002]

2. Description of the Related Art A network control device of this kind receives a so-called no-ringing signal activated by a no-ringing call signal so as not to ring a bell of a telephone connected in parallel, and also performs an insulation test performed from a telephone line. It is necessary to have high impedance.

[0003] As such a network control device, conventionally, FIG.
And Japanese Patent Publication No. 62-14149 as shown in FIG. In the network control device shown in FIG. 3, a high-voltage analog switch unit 2 and a low-voltage analog switch unit 4 are connected in series between a telephone line connection terminal L2 and a terminal device 5, and a telephone line connection terminal L1 is connected.
Is connected to a cathode of a backflow prevention diode 3, and a bistable circuit 6 is connected between the common return GND to which the anode of the diode 3 is connected and the low-voltage analog switch section 4. ing. Further, a release signal 7 is supplied to the bistable circuit 6 from the terminal device 5. The high-voltage analog switch section 2 includes a high-voltage detection circuit, and the low-voltage analog switch section 4 includes a low-voltage detection circuit.

Next, the operation of the circuit block diagram of FIG. 3 will be described. Normally, a voltage having a negative polarity at the terminal L2 is applied between the subscriber telephone line connection terminals L1 and L2. The polarity reversal of the subscribed telephone line occurs due to no ringing reception, and L2
When the terminal voltage becomes positive, a voltage is applied to the high-voltage analog switch unit 2. When this voltage is lower than the detection voltage of the high voltage detection unit, the switch is turned on, and when this voltage is higher, the switch is turned off. When the high-voltage analog switch unit 2 is turned on, a voltage is applied to the low-voltage analog switch unit 4 and the bistable circuit 6. The bistable circuit 6 short-circuits the return line of the low-voltage analog switch unit 4 and the common return line of the subscribed telephone line by an internal switch, so that the low-voltage analog switch unit 4 can be turned on. . On the other hand, when a voltage is applied to the analog switch unit 4 for low voltage, an internal low-voltage detection circuit operates. At this time, when the low-voltage analog switch unit 4 is turned on and a voltage is generated at the output, the bypass circuit operates and the low-voltage detection circuit is bypassed.
Thus, when the low-voltage analog switch unit 4 is turned on, the on-state is maintained even if the input voltage subsequently becomes lower than the detection voltage of the low-voltage detection circuit.
Therefore, a voltage equal to or lower than the high detection voltage and equal to or higher than the low detection voltage is input to the terminal device 5. The terminal device 5 is activated by application of a voltage, and subsequently transmits and receives data when its own terminal device is selected by a terminal device selection signal input from a subscriber telephone line. At this time, if the terminal device selection signal cannot be received, or if the terminal device itself has not been selected, the release signal 7 is transmitted to the bistable circuit 6. Release signal 7
Is input, the bistable circuit 6 cuts off the internal switch that short-circuits the return of the low-voltage analog switch 4 and the common return of the subscriber telephone line. As a result, the low-voltage analog switch section 4 cannot be turned on,
It turns off. At this time, no voltage is applied to the terminal device 5 and the release signal 7 stops, but the bistable circuit 6 maintains a state in which the low-voltage analog switch unit 4 cannot be turned on. FIG. 4 is a circuit diagram showing a detailed configuration of the circuit block diagram of FIG. The configuration of the figure will be described below for each block.

The high-voltage analog switch section 2 includes an NPN transistor Q21 as a main switch connected in series to the subscriber telephone line, and a transistor connected to the base of the transistor Q21 for controlling the transistor Q21. Q22, one Zener diode ZD21 having one connected to the base of transistor Q22 and the other connected to the subscriber line via resistor R21, bias resistor R22 of transistor Q22, and bias resistor R23 of transistor Q21. Become. The low-voltage analog switch section 4 includes a transistor Q41 of a switch body connected in series to the output of the high-voltage analog switch section 2, and a resistor R connected to the base of the transistor Q41.
Zener diode ZD41 connected via
And a bias resistor R41 of the transistor Q41, a transistor Q42 connected in parallel with the Zener diode ZD41, one of which is connected to the base of the transistor Q42, and the other of which is connected to the transistor Q41 via the resistor R43.
And a bias resistor R44 of a transistor Q42.

The bistable circuit 6 is connected between the return of the low-voltage analog switch section 4 and a common return, and controls the state of the transistor Q for controlling the state of the low-voltage analog switch section 4.
62 and a base of the transistor Q62.
Transistor Q61 for controlling transistor Q62
And a resistor R62 connected in series between the base of the transistor Q62 and the output of the high-voltage analog switch section 2.
A resistor R61 connected to the output of the high-voltage analog switch unit 2, a diode D61 connected between the resistor and the base of the transistor Q61, and a resistor R61 connected between the resistor R61 and the collector of the transistor Q62. And a capacitor C61 connected between the common return and the base of the transistor Q61, and a resistor R63 connected between the common return and the release signal line 7.

Next, the operation in the circuit diagram of FIG. 4 will be described. When a voltage is applied to the subscriber telephone line terminal L2, the high-voltage analog switch unit 2 applies a voltage to the base of the transistor Q21 via the resistor R23,
21 turns on. At this time, the voltage becomes Zener diode Z
When the voltage is higher than the Zener voltage of D21, the Zener diode ZD21 becomes conductive and current flows through the resistors R21 and R22. When the voltage generated at both ends of the resistor R22 becomes a voltage at which the transistor Q22 is turned on (hereinafter referred to as Vf voltage), the transistor Q22 is turned on, and the potential at the base of the transistor Q21 is reduced to the value of the common retrace. , The transistor Q21 is turned off.

When the high voltage analog switch section 2 is turned on,
When a voltage appears at the output, in the bistable circuit 6, the resistor R6
1 and R62, a voltage appears at the bases of the transistors Q61 and Q62. Since the base of the transistor Q61 has the capacitor C61, the capacitor C61
61 is charged. Therefore, the base potential of the transistor Q61 does not rise, and the transistor Q61 does not turn on.
On the other hand, the base of the transistor Q62 has the transistor Q61 but is not turned on, so that the potential of the base of the transistor Q62 rises and the transistor Q6
1 is turned on. As a result, the potential of the resistor R61 drops through the diode D62, and the transistor Q61
Becomes lower than the Vf voltage, and the transistor Q6
1 is off and Q62 transistor Q62 is on and stable.

On the other hand, the low voltage analog switch section 4
Since the transistor Q62 of the bistable circuit 6 is ON, a voltage is applied to the Zener diode ZD41 via the resistor R42. At this time, if the value of the voltage is equal to or higher than the Zener voltage of the Zener diode ZD41, the Zener diode ZD41 becomes conductive and current flows. The voltage generated at both ends of the resistor R42 is
When the Vf voltage reaches 41, the transistor Q41 is turned on. When the transistor Q41 is turned on, a voltage is generated at the output, and a current flows to the resistor R44 through the resistor R43 and the diode D41. At this time, the resistor R44
When the voltage generated at both ends of the transistor becomes the Vf voltage of the transistor Q42, the transistor Q42 is turned on to form a current route that bypasses the Zener diode ZD41.
41 continues to be in the ON state.

When the release signal 7 is output from the terminal device 5, the capacitor C61 is charged through the resistor R63, and the base potential of the transistor Q61 is
When the Vf voltage reaches 61, the transistor Q61 is turned on. As a result, the base potential of the transistor Q62 decreases, and the transistor Q62 is turned off. When the transistor Q62 is turned off, the diode D62
And the current flows toward the diode D61. After the release signal stops, the transistor Q
61 is turned on. The transistor Q61 is stable in the ON state and the transistor Q62 is stable in the OFF state.

When the transistor Q62 is turned off,
The base current of the transistor Q41 of the low-voltage analog switch section 4 is cut off, the transistor Q41 is turned off, the output voltage of the transistor Q42 is also lost, and the transistor Q42 is turned off. Next, the overall operation will be described. First, when a positive voltage is applied to the subscriber telephone line terminal L1, no current flows due to the backflow prevention diode 3. Therefore, the DC resistance is very high.

Next, when the polarity of the telephone line is inverted and no-ringing is received by the terminal device selection signal and a positive voltage is applied to the telephone line terminal L2, the high voltage analog switch unit 2 is turned on. The bistable circuit 6 turns on the analog switch unit 4 for low voltage, the analog switch unit 4 for low voltage turns on, and the terminal device 5 starts operating. Then, a terminal device selection signal is determined, and when the own device is selected, data transmission is performed.

In the insulation test, when the telephone line terminal L2 is set to have a positive polarity and a voltage higher than the Zener voltage of the Zener diode ZD21 is applied, the high-voltage analog switch unit 2 is turned off. The DC resistance at this time is equal to or greater than the combined resistance value of the resistors R21 and R23.

In the insulation test, the telephone line terminal L
When the voltage on the second side is positive and a voltage equal to or lower than the Zener voltage of the Zener diode ZD41 is applied, the high-voltage analog switch section 2 is turned on, and the bistable circuit 6 turns the low-voltage analog switch section 4 on. However, since the Zener diode ZD41 does not become conductive, the low-voltage analog switch unit 4 is turned off.

Furthermore, in the insulation test, the telephone line terminal L
When the voltage on the two sides is positive and a voltage equal to or higher than the Zener voltage of the Zener diode ZD41 and equal to or lower than the Zener voltage of the Zener diode ZD21 is applied, the terminal device starts operating as in the case of the above-mentioned no-ringing reception. Since the signal cannot be detected, the release signal 7 is transmitted after a predetermined time. As a result, the bistable circuit 6 cannot turn on the low-voltage analog switch section 4, and the low-voltage analog switch section 4 is turned off. At this time, the DC resistance of the line is equal to or greater than the combined resistance value of the resistors R61 and R62.

[0016]

In the above-described network control device, it is necessary to specify the polarity of the telephone line connected to the line connection terminal by the diode, and it operates when the polarity of the telephone line is changed after the device is connected. There was a problem that it disappeared.

In the above-described network control device, when the voltage of the telephone line becomes equal to or higher than the detection voltage of the low-voltage analog switch, the switch is always in a conductive state. At this time, as described above, the terminal device issues the release signal, but there is a problem that the voltage waveform on the telephone line is distorted due to the input impedance of the terminal device. When a diode bridge is used to solve the problem of the polarity of the telephone line and the designation of the polarity is canceled, the number of voltage changes applied to the low-voltage analog switch increases. Becomes more conductive,
The number of malfunctions such as distortion of the voltage waveform on the telephone line also increased, and there was a risk of affecting the voltage change due to the switching operation.

An object of the present invention is to provide a network control device which does not specify the polarity of the line connection terminal and does not affect the voltage change due to the switching operation other than the no ringing call. [Configuration of the Invention]

[0019]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is connected between a telephone line and a terminal device, is called by a no-ringing incoming signal from an exchange, and connects the telephone line to the terminal device. A network control device, comprising: a diode bridge connected between telephone lines so that line voltage polarities of telephone lines are aligned in a certain direction; and a low-voltage reference signal that is normally output and a high-voltage reference signal is output under predetermined conditions. A reference voltage generating means for comparing the reference signal from the reference voltage generating means with the rectified line voltage from the diode bridge, and outputting a signal when the reference signal is large, and a predetermined time at the fall of the output signal of the comparing means. A signal is output at the rising edge of the output signal of the first timer which outputs the signal and the comparing means, and the output signal of the reference voltage generating means is changed to the high voltage reference signal by this output signal. Rutotomoni, a second timer is cleared by the output signal of the comparator means and the first timer is provided between the terminal device and the diode bridge,
It is composed of a second timer and switch means that is closed by each output signal of the comparison means.

[0020]

In such a configuration, the first timer outputs a signal for a predetermined time at the rising edge of the output signal of the comparing means, the second timer outputs a signal at the rising edge of the comparing means, and the output signal provides a reference voltage. The output of the generating means is a high-voltage reference signal, and the opening and closing of the switch means is controlled by being cleared by the respective output signals of the first timer and the comparing means. It does not affect the voltage change during operation.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a network control device according to an embodiment of the present invention. In FIG. 1, a telephone line connection terminal L is connected to a telephone line, and is connected to a primary side of a diode bridge 1. On the secondary side of the diode bridge 1, divided resistors R1 and R2 connected to the input of the voltage detection comparator 2 and a switch circuit 6 for opening and closing the line are connected. Further, a terminal device which detects an NRS signal by a non-ringing call (not shown) and communicates with the center device via a network control device and a telephone exchange network is connected to a subsequent stage of the switch circuit 6.

The output of the detection reference voltage circuit 5 is connected to the other input of the voltage detection comparator 2. The output of the voltage detection comparator 2 is connected via a NOT circuit 9 to the input side of the timer circuit 3, the input sides of the AND circuits 7 and 8, and the input side of the timer circuit 4.

The timer circuit 3 is composed of, for example, a monostable multivibrator, and is output at the rising edge of the output signal of the voltage detection comparator 2 input via the NOT circuit 9 (rising at the input of the timer circuit 3 by the NOT circuit 9). Is sent. The output of the timer circuit 3 is A
It is connected to the input side of the ND circuit 7. Timer circuit 3
Is set shorter than the time from when the voltage detection comparator 2 detects the low voltage to when the high voltage is detected by the no ringing call. The output of the AND circuit 7 is connected to the clear input of the timer circuit 4. The timer circuit 4 is composed of, for example, a monostable multivibrator, and sends out an output at the rising edge of the output signal of the voltage detection comparator 2,
The output is stopped even during activation by the clear input from the D circuit 7. The output side of the timer circuit 4 is connected to the input side of the NAND circuit 8 and the input side of the detection reference voltage circuit 5. The transmission time of the output signal of the timer circuit 3 is a time sufficient for a terminal device (not shown) to receive the NRS signal.

The detection reference voltage circuit 5 outputs a low-voltage detection reference voltage when a signal from the timer circuit 4 is not input, and outputs a high-voltage detection reference voltage when a signal is input.

The output side of the NAND circuit 8 is connected to the switch circuit 6
When the output of the timer circuit 4 and the output of the voltage detection comparator 2 are present, the switch circuit 6
Close. A signal is also input to the control input side of the switch circuit 6 from a terminal device (not shown).

Next, the operation will be described with reference to FIG. FIG. 2 is a waveform chart showing the operation of the network control device of the present invention. Assuming that the gentle reversal due to the no ringing call is applied to both ends of the telephone line connection terminal L, a waveform as shown in the rectified line voltage V in FIG. 2 appears on the secondary side of the diode bridge 1 regardless of the polarity.

As the rectified line voltage V decreases, at the time point a at which the resistance-divided input of the voltage detection comparator 2 becomes lower than the low-voltage detection reference voltage of the detection reference voltage circuit 5,
The output of the voltage detection comparator 2 changes as shown in FIG. At this time, the timer circuit 3 outputs a signal as shown in FIG.

Further, when the rectification line voltage V starts to rise due to the reciprocity due to the no ringing call, at the point of time b at which the resistance divided input of the voltage detection comparator 2 becomes higher than the low voltage detection reference voltage of the detection reference voltage circuit 5. The output of the voltage detection comparator 2 changes as shown in FIG.
At this time, the timer circuit 4 outputs a signal as shown in FIG. The detection reference voltage circuit 5 outputs a high-voltage detection reference voltage to the voltage detection comparator 2 because the signal is input.

When a high-voltage detection reference voltage is output, at this time, the rise of the rectification line voltage V due to the no ringing call is slow. It becomes lower than the voltage detection reference voltage. Then, the output of the voltage detection comparator 2 changes, and the timer circuit 3 outputs a signal as shown in FIG.

When the rise of the rectified line voltage V due to the no ringing call proceeds, at the time C at which the resistance divided input of the voltage detection comparator 2 becomes higher than the high voltage detection reference voltage of the detection reference voltage circuit 5, the voltage detection comparator 2 Changes as shown in FIG. At this time, the NAND circuit 8 outputs a signal as shown in FIG. 2D and closes the switch circuit 6 because both signals are applied to the input.

Thereafter, a terminal device (not shown) detects an NRS signal by a no-ringing call, and
When the S signal is detected, a signal for closing the switch circuit 6 is issued from the terminal device. When the NRS signal is not detected, the output signal disappears depending on the output time of the timer circuit 4. Therefore, the output of the NAND circuit 8 also becomes as shown at D in FIG. 2, and the switch circuit 6 is opened.

Next, it is assumed that the line voltage has changed due to an exchange operation other than the no ringing call. At this time, since the change in the rectification line voltage is faster than the slow reversal due to the no ringing call, the time from a to b in FIG.
And c becomes short, and the output of the voltage detection comparator 2 changes while the output of the timer circuit 3 is present. Therefore, the AND circuit 7 outputs a signal, and the timer circuit 4 stops or does not emit the signal. Therefore, since neither signal is applied to the input of the NAND circuit 8, the switch circuit 6 does not close.

In the above embodiment, the voltage detection comparator is performed by one circuit, but the voltage detection may be performed by using a plurality of voltage detection comparators. Also,
The output time when the rectification line voltage V waveform falls and the output time when the rectification line voltage V waveform rises in the waveform B in FIG. 2 may be set by different timer circuits.

[0035]

As described above, according to the present invention, it is not necessary to specify the polarity of the telephone line connected to the line connection terminals L1 and L2, and a sudden change in the line voltage due to the switching operation other than the no ringing call. However, since the switch does not become conductive, the problem that the voltage waveform on the telephone line is distorted due to the input impedance of the terminal device does not occur, and the voltage change due to the switching operation other than the no ringing call is not affected, and the no ringing call is performed. Can obtain a network control device that can detect

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a network control device of the present invention.

FIG. 2 is a waveform chart showing the operation of FIG.

FIG. 3 is a configuration diagram of a conventional network control device.

FIG. 4 is a circuit diagram of FIG. 3;

[Explanation of symbols]

2 ... voltage detection comparator, 3 ... timer circuit, 4
…… Timer circuit, 5 …… Detection reference voltage circuit, 6 …… Switch circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04M 11/00-11/10

Claims (1)

(57) [Claims] 1. A connection between a telephone line and a terminal device,
A network controller that is called by a no-ringing incoming signal from the exchange side and connects a telephone line to a terminal device, and a diode bridge connected between the telephone lines so that the line voltage polarity of the telephone line is aligned in a fixed direction. Normally, a reference voltage generating means for outputting a low voltage reference signal and outputting a high voltage reference signal under predetermined conditions, and comparing the reference signal from the reference voltage generating means with the rectified line voltage from the diode bridge, the reference signal A signal that outputs a signal when the output signal of the comparison means falls, a first timer that outputs a signal for a predetermined time when the output signal of the comparison means falls, and a signal that is output when the output signal of the comparison means rises. To make the output signal of the reference voltage generating means a high voltage reference signal, and clear by the output signals of the comparing means and the first timer. That a second timer is provided between the terminal device and the diode bridge, a network control unit and a switching means for closing operation by the output signal of the comparison means and the second timer.