JPS59221147A - Ring trip circuit - Google Patents

Abstract

PURPOSE:To reduce an operating and restoring time by separating a signal voltage superimposed on a call signal into a positive and a negative voltage, and comparing a value obtained by multiplying an absolute value of the positive voltage by a prescribed coefficient, with the absolute value of the negative voltage to eliminate the need for a low pass filter. CONSTITUTION:Each absolute value of positive and negative superimposed voltages is held respectively in capacitors C1, C2 by inputting a voltage between a terminal (a) of a resistor Ra and ground to an operational amplifier OP1 after the voltage is divided at resistors R1, R2. As a result, the absolute value of potentials of points A and B is equal to each other at on hook and the absolute value of the potential at the point B is larger than the absolute value of the potential of the point A at off-hook, then the detection of ring trip is attained. Since the detection becomes unstable if this state is left as it is, the amplification factor of operational amplifiers OP1, OP2 has only to be changed depending on on-hook and off-hook.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) 6 Technical Field of the Invention The present invention relates to ring trip circuits, and more particularly to telephone exchanges or PQMI! ! The present invention relates to a ring trip circuit that monitors the called party's response at the signal converter of the transmitting station.

(Middle), Prior Art and Problems The ring trip circuit is a circuit that controls the stopping of the ringing signal (16 Hz intermittent alternating current in our country) that operates the bell of the called telephone.

FIG. 1 shows an embodiment of a conventional ring trip circuit, in which the device in the figure is a telephone, PL and B2 are batteries and RA.
is a relay that receives the output of this ring trip circuit and operates under CPU control, RC is a ring signal transmitter, and R1
-4 is a resistor, LPF is a low-pass filter that extracts only the DC component, and GOMP is a comparator.

In ff1lryJ, when the telephone device is on-hook [hereinafter referred to as (A) state], the voltage drop across resistor R1 is v1.
The DC component of is approximately 0, and is only the calling signal component. On the other hand, when the telephone device is off-hook (hereinafter referred to as the (B) state), a DC component of voltage drop 1 appears across the resistor R1, and at the same time a ringing signal also appears.

Next, in the voltage F2 after passing through the low-pass filter LPF, the ringing signal component is attenuated, so in state (A) it is approximately OV, and in state (B) only a voltage drop of the DC component appears.

In the conventional technology, the comparator COMP uses a potential that is fixed as a threshold value, which is an intermediate value between the minimum value of the voltage drop of the DC component in the (B) state and the maximum value (OV) of the voltage drop of the DC component in the (Δ) state.
It was done manually.

However, in this case, due to the transient characteristics of the low-pass filter LPF, (
In the state of transition to A) state = (B) state, the operating time is maximum when ■2 is minimum, and in the state of transition to state (B) - (A), recovery time is maximum when v2 is maximum. It became.

Figures 2 and 3 show the transition from (A) state to (B) state, (
B) State 9-(p, This is the time until it becomes equal to . Note that T2 and T4 are the times until V3 becomes equal to V5.

In both figures, the calling signal component is attenuated by the low-pass filter LPF, so for convenience only the change in the DC component is shown.

In actual operation, a ring signal is supplied to the telephone station, and when the telephone is taken off-hook, the main ring trip circuit operates and switches the RA relay, and the main jig trip circuit is restored and the ring signal is output again. You will have to wait.

During the transition from state (A) to state (B), if the output from this ring trip circuit is delayed, the ringing signal will continue to be emitted when the telephone is taken off the hook and brought to the ear, which may be jarring. Become. In addition, when transitioning to state (B) y3-(A), in the series of operations of activation (calling party) - call-response-recovery-call-response, from one response to the next call. If the recovery time takes longer than the above time, the RA relay will operate automatically because the ring trip circuit will continue to output output even if the telephone is not taken off-hook.

In the conventional circuit, the transition from the (A) state to the (B) state and the transition from the (R3) state to the (A,) state take time, which may cause the above-mentioned drawbacks.

(C)9 Purpose of the Invention The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art;
An object of the present invention is to provide a ring trip circuit that does not use a low-pass filter and has a short operating time and recovery time.

(d) 0 Structure of the Invention According to the present invention, the present invention provides a detection circuit for detecting a superimposed signal of a DC voltage signal and a ringing signal generated depending on whether a called subscriber raises or lowers a telephone set. , comprising a separation circuit that separates the superimposed signal voltage into a positive voltage and a negative voltage, and a comparison circuit that compares the absolute value of the positive voltage multiplied by a predetermined coefficient and the absolute value of the negative voltage. This is accomplished by providing a ring trip circuit characterized in that it performs ring trip detection.

(e) 9 Embodiments of the Invention Figure 4 shows an embodiment of the present invention.
5 is a resistor, DI, D2 is a diode, D3, D4 are Zener diodes, CI, C2 are capacitors, 091~
3 is an operational amplifier, OF2 is a comparator, R6 and R7 are line resistances, and ra is a contact that receives the output of this ring trip circuit and operates under CPU control.

The present invention will be described in detail below with reference to FIG.

The present invention focuses on the difference between the absolute values of the calling signal superimposed on the direct current flowing through the subscriber line on the positive side and negative side from the ground potential.

That is, the DC potential at the terminal a point of the resistor Ra is 0 when the telephone is on-hook. Therefore, the absolute values of the positive and negative sides of the alternating current component at this time are approximately the same.

However, when the telephone is off-hook, a direct current flows through the subscriber line, creating a potential difference across resistor Ra. Therefore, since DC voltage and AC voltage are superimposed, the absolute values of the positive side and negative side of the AC component at this time will be different, and the absolute value of the negative side will be larger than the absolute value of the positive side. .

Therefore, the voltage between the terminal a point of the resistor Ra and the ground is the resistor R1
, R2, the voltage is input to the operational amplifier OPI, and the output voltage is decomposed into positive and negative sides by diodes D1 and D2, respectively, and charged to capacitors C1 and C2. In this way, the absolute value on the positive side and the absolute value on the negative side are connected to capacitors C1 and C, respectively.
You can hold it at 2.

As a result, when the phone is on-hook, the absolute values of the potentials at points A and B are equal, while when the phone is off-hook, the absolute value of the potential at point B is equal to the absolute value of the potential at point A. greater than the value.

However, in this situation, the detection of telephone on-hook is unstable, so the absolute value of the potential at point A is slightly increased (for example, the amplification degree of operational amplifier OP2 is made slightly larger than the amplification degree of operational amplifier OP3). Therefore, when the phone is on-hook, the absolute value of the potential at point A is greater than the absolute value of the potential at point B, while when the phone is off-hook, the absolute value of the potential at point B is less than the potential at point A. By making it larger than the absolute value, it becomes possible to easily detect a ring trip in comparator OP4.

The diodes D3 and B4 are used to protect the circuits below the operational amplifier OP1 when an abnormally high voltage is applied from the line side.

(f) 9 Effects of the Invention As described in detail above, the present invention has the great effect of realizing a ring trip circuit that does not use a low-pass filter and has a short operating time and short recovery time.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of a conventional ring trip circuit, in which the device in the figure is a telephone, B1 and B2 are batteries, and RA
takes in the output of this ring trip circuit and sends it to the CPU.
Relay operated by control, RC is a calling signal transmitter, R
1 to 4 are resistors, LPF is a low-pass filter that extracts only the DC component, and COMP is a comparator. Figures 2 and 3 show the transition from state (A) to state (B), (
B) State - (A) This represents the waveforms of Vl, V2, V3 (conventional), and ■5 in the state where the time at the time of transition to the state is maximum, and T1 and T3 are maintained until V2 becomes equal to V3. It's time. Note that T2 and T4 are the times until V3 becomes equal to ■5. FIG. 4 shows an embodiment of the present invention. In the figure, mount is a telephone, B is a battery, RC is a calling signal transmitter, Ra, R1 to
5 is a resistor, DI, B2 is a diode, B3, B4 are Zener diodes, C1, C2 are capacitors, OPI~
3 is an operational amplifier, OF2 is a comparator, R6 and R7 are line resistances, and ra is a contact that receives the output of this ring trip circuit and operates under CPU control. -26: Mouth to mouth

Claims (1)

[Claims] A detection circuit that detects a superimposed signal of a DC voltage signal and a ringing signal generated depending on whether the called subscriber raises or lowers the telephone, and a separation circuit that separates the superimposed signal voltage into a positive voltage and a negative voltage. and a comparison circuit that compares a value obtained by multiplying the absolute value of the positive voltage by a predetermined coefficient and the absolute value of the negative voltage to detect a ring trip. circuit.