JPS6076855A - Transmission system of metering pulse - Google Patents

Abstract

PURPOSE:To unify a DC feeder and a charging filter for the miniatrurization of a metering pulse transmission system by providing both detecting and feedback means for a feed current to the DC feeding circuit of a public telephone set and adding a holding means at the middle between said two means together with an integration circuit which uses the output of the holding means as an input. CONSTITUTION:A DC feeding circuit 1 is connected to a telephone set RL via a polarity inverting switch K2. A current detector outgoing line 15 of the circuit 1 is connected to a current mirror 2, and a feedback input line 16 is connected to a current mirror 3 respectively. The voltage V31 produced by a detection current I1 and a resistance 31 is held by a holding circuit 5 and the voltage is divided to obtain the input of an integration circuit 4. A control switch K1 is first turned on and therefore the output voltage of the circuit 4 is gradually reduced. A load current Im is also reduced gradually. Then a switch K2 is inverted and the output of the circuit 4 increase gradually. At the same time, a load current Im also increases gradually from zero to obtain a current In. The metering pulse is produced with the increment and decrement of the currents Im and In.

Description

DETAILED DESCRIPTION OF THE INVENTION (c) Technical Field of the Invention The present invention relates to a billing pulse transmission system, and particularly to a billing pulse transmission system in a subscriber circuit for a public telephone set of an electronic exchange.

(BL, Prior Art and Problems) Miniaturization and economicalization of equipment are important issues in electronic exchanges, and it is also necessary to digitize billing filters in subscriber circuits for public telephones.

FIG. 1 is a diagram showing an embodiment of a conventional subscriber circuit for a public telephone set.

In the figure, A and B are output terminals, 101 is a telephone, 102 is a charging filter consisting of a choke coil and a capacitor-IIC, 103 is a polarization switch, 104 is a letter coil that supplies DC current, and vbb is a DC power supply. It is.

The subscriber circuit for the public telephone is connected to the DC power supply VBB, and supplies 1 m of DC current to the public telephone 101 via the letter coil 104 - polarity reversal switch 103 - billing filter 102 - terminal A13, and the polarity reversal switch. By inverting the signal 103 for a predetermined time (from one million to several hundred m S ), a charge pulse (negative direction current 1 n') is sent to the public telephone 101 to prompt the public telephone 101 to collect money.

Here, when the supply current changes rapidly due to the polarity reversing switch 103, high HLD wave noise is generated in the public telephone 101 and the communication circuit, so the billing filter 102 is used to reduce the noise.

In subscriber circuits for public telephones, billing filters play an important function and are indispensable.The choke coil is a few Henrys and the capacitor C is several tens of microfarads, so billing filters play an important function and are indispensable. The filter was large and had the disadvantage that it was impossible to downsize the subscriber circuit for public telephones.

(0) Purpose of the Invention The objective of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to propose a charge pulse sending method that does not require a large choke coil or a large capacitor. There is.

According to the present invention, in a subscriber circuit that supplies DC'III current to a public telephone (shallow), a DC power supply circuit is connected to the DC power supply circuit. A means for detecting the feeding current (1), a means for detecting the feed current (1), a means for holding the voltage or current at the intermediate point between the detection means and the 11th feedback stage (1), and a means for maintaining the voltage or current at the intermediate point (1), Based on the output (as input to 1 and 1 production, 1-I2°tsuliri')
and (, an integrating circuit for controlling S<811 to stop S<+1 is provided, and the output of the integrating circuit is connected to drive OJ at the intermediate point between the detecting means and the feedback means described in 1). This is achieved by providing a billing pulse sending method characterized by the following.

(e) 1 Examples of the invention FIG. 2 is a detailed diagram of one embodiment of the present invention.

In the figure, 1 is a DC power supply circuit, 2 and O.; 3 are Karen 1-.
Mirror, 4 is operational amplifier ○P, resistor 1. ? 1, an integrating circuit consisting of a capacitor C1, 5 a holding circuit,
6 is a diode (1, 3), 51.52 is a resistor, K1.
1 and 2 are polarity reversing switches, respectively, and 8 and B are output terminals.

Further, FIG. 3 is a diagram for explaining the operation of glue 3 in FIG. 2.

In FIG. 3, fal is the operation of the control]11 switch 1<], (bl is the operation of the control switch 2, (C1 is the change in voltage Vc, tdl is the change in voltage VR, (e+ is the negative i
It is a figure which shows the change of I current 1m and In.

The present invention will be described in detail below with reference to FIGS. 2 and 3.

DC power supply circuit 1 has a pair of output amplifiers 1 Vj 1 device Table 71 As shown in FIG.

Also, the 71i source line 13 and the earth air line 14 of the direct 1% c supply circuit 1 are connected to the direct electricity l↓',! V bh and earth Q are connected, and the current detector output line 15 is connected to the current mirror 2's power,
Feedback input line 16 31 power 1. -1 and -3, respectively.

Output 21 of current me'/-2 is in series 1 with resistor 31
x is successively connected to the inputs of Karen 1-Mirror 3, and further (
Input line with λj rotation l/85 and anode I' of diode 6
1 min 6 □. ('A; The output of the long circuit 5 is the input of 1 to the control switch, and the reference input line 41 of the voltage divider consisting of the resistor 51 and the resistor 52 is 1'Y°, shift, 4111 division I1 + 84 is divided Pressure generator output and human power line 42 of integral circuit 4
For example, it is connected to the control switch 1, and the power line 43 is connected to the diode 1-6's IC1.

1iir (In the continuation configuration, the positive electrode time (normal power supply) shown in FIG. A current of 1 is passed through the load resistor 1'?L, and a current of 11 proportional to the current of 1 m is obtained in the current detection line 15.

The detection current 11 is passed through the current mirror 2, the resistor 31, and the current mirror 3 to the (l) of the pJ DC power supply circuit.
'i3 Return input line Performs M return of input line 16I2.

The current It and the resistor 31 cause the electric current J3-V to emit light 4''.
3] is input to the holding circuit 5, output voltage V17 of the holding circuit 5 is output, and its divided voltage output is applied to the reference human power line 41 of the integrating circuit 4.

At this point, manually turn 1 off to the control switch (V bl + (1
111), apply the voltage vbb to the integral input line 42,
The voltage value Vc of the output line 43 of the integrating circuit 4 is set so that the quote 6 becomes reverse biased.

Therefore, in this state, the output of the integrator circuit 4 is cut off by the tie-out 6, so the power supply operation is performed with the detection current 11 and the feedback current I2 being equal, and the negative (rdh current 1 m) takes into account the change in load resistance. The output voltage V++ of the holding circuit 5 and the output voltage Vc of the integrating circuit 4 change as the maximum and minimum values change when
It also changes to the maximum value and minimum value.

When sending charging pulses, polarity reversal 11, not shown in FIG.
'l' l! ! I (reverse water (1μ)), first turn on the control switch Kl, and apply the output voltage Vl+ of the holding circuit 5 to the input line 42 of the integrating circuit 4. As a result, the output voltage value VC of the integrating circuit 4 becomes l+, Danger 1) 1lli at 1τ1
Diode 6 is forward biased at a voltage where Vc<VS2, and 2''I, ゛C exclusive, V
S2 becomes a voltage equal to Vc.

Therefore, the input current I2 of Karen I...mirror 3 is 12
= Vc / R31, which is proportional to Vc (ijj
Since the DC supply circuit 1 is driven by the return current, the negative iI current 1m is reduced by I41i and becomes O as shown in (!) in Figure 3.
The output current becomes 1).

Next, the control switch 2 is turned in the reverse direction at time L2 as shown in FIG. 3(b), and at time L1, 1 is turned 11J to the control switch and the OFF input (Vbb side) is made.

The output of integrating circuit 4 is from QV!・Increase R1 and see (in Figure 3)
Since the current mirror 3 is driven by obtaining a voltage that reaches the voltage Vc in a time τ2 when C1 stops, and the DC supply circuit 1 is driven with a feedback current proportional to the voltage VC, the negative current 1m is again An output current that gradually increases from 0 and becomes a current In in the opposite direction is obtained due to the effect of turning the control switch 2 in the reverse direction.

Furthermore, after the required time T, the control switch 1 and the control switch 2 are controlled in the same manner as the control procedure described above, and the reverse direction 767
When the polarity is reversed so that the current In is decreased by 1 m/gi and increased by 1 m to the stop direction load current, a charge pulse current as shown in ((g)) in FIG. 3 is obtained.

In the billing pulse current sending operation described above, the time for gradual decrease and gradual increase in the output current of the DC supply circuit 1 is determined by the output voltage value Vc of the integrating circuit 4.

That is, the resistance R1 and the content C of i) 1 of the integrating circuit 4
It is determined by the time constant determined by I and the voltage applied to the reference input line 41 and the input line 42 of the integrating circuit 4, and the load voltage is 1 m.
When the voltage changes, the output voltage V of the circuit 5 is maintained proportionally.
Since R also changes and the input voltage value of the integrating circuit 4 is controlled, a constant gradual decrease and increase time can be obtained. In this way, the DC current supply and billing filter can be integrated, and billing pulses can be easily transmitted.

(f) Effects of the Invention As described in detail, according to the present invention, billing pulses can be transmitted without using a large choke coil or large capacity content, so that the device can be made smaller. If economicization can be measured, there will be big benefits.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a conventional subscriber circuit for a public telephone set. FIG. 2 is a diagram showing an embodiment of the present invention. FIG. 3 is a diagram for explaining the operation of FIG. 2. 1-2. Agent Patent attorney Hiroshi Matsuoka p11...White ゛JΦ□□□□□

Claims (1)

[Claims] In subscriber circuits that supply direct current to public telephones,
It comprises a DC power supply circuit, a means for detecting a power supply current connected to the DC power supply circuit, and a feedback means, and a means for maintaining a voltage or current at a connection intermediate point between the detection means and the feedback means; The output of the means !, (〆p! It is equipped with an integrating circuit which operates manually and whose operation is started and stopped by an external control 311, and the output of the integrating circuit described in 11J is connected to the connecting intermediate point between the detecting means and the feedback means. A billing pulse sending system characterized by being connected so as to drive.