JPH0218631B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the transmission of public charging pulses in an automatic telephone exchange that immediately transmits charging pulses to public telephones.

FIG. 1 shows an example of a conventional configuration, in which a charging pulse sending trunk (TRK) is connected to a subscriber terminal 1 via a subscriber line 2, and the trunk (TRK) has inductances of 3, 4, 6, It consists of electromagnetic parts such as an LC filter (LCF) consisting of 7 and capacitors 5 and 8, current reversal relay contacts 9, 10, 11, 12, and a current supply circuit 13. When sending charging pulses, the current reversal relay contact 9, 10, 11, and 12 are inverted, the LC filter (LCF) absorbs the sudden current change caused by the inversion, and the billing pulse LA1 with less noise as shown in FIG. 2 is sent to the subscriber terminal. I was configuring it. In FIG. 2, 20 is a control signal for current reversing relays 9 and 10, and 30 is a current reversing relay 1.
1 and 12 control signals.

Such conventional trunks for transmitting billing pulses are composed of electromagnetic parts and cannot be made smaller and lighter or more integrated, and the noise removal filter always operates when connecting or disconnecting a circuit, resulting in the transmission of response accommodation and storage signals. It takes a long time, and it takes about 100 ms for the subscriber loop current I _L to become zero even in the case of forced disconnection, and there are disadvantages such as the invalid hold time of the public charge pulse sending circuit becomes longer.

The present invention has a configuration in which an equivalent power supply in a current supply circuit is driven by a constant current source, and the constant current source is controlled by an output signal of a filter whose input is a step signal for sending charging pulses. The present invention provides a public billing pulse sending circuit which is suitable for electronic or integrated circuit implementation, has excellent billing noise suppression characteristics, and can shorten operation delay time during forced disconnection, and will be described in detail below. do.

FIG. 4 shows a configuration example of the present invention, in which the same circuit is provided on the normal side and the reverse side, and the circuits are arranged so that the polarities of the outputs of the A and B lines are opposite.

1 is a subscriber terminal, 2 is a subscriber line, 40, 50
1 is a current supply circuit, and 41 and 51 are constant current sources for controlling the current supply circuit. 42, 52 are CR integration circuits,
43 and 53 are constant current integration circuits, which constitute filter sections 61 and 71. 44, 54 are buffer circuits, 45, 55 are filter control switches, 46, 56 are charge pulse sending control terminals, 60
is the control terminal for the filter control switch.

Next, the operation will be explained. Charging pulse sending signals 47 and 57 shown in FIG. 3 are applied to charging pulse sending control terminals 46 and 56 shown in FIG. 4, respectively. When transmitting the response storage signal (T ₁ hour), if the filter control switches 45 and 55 are closed, the charging pulse transmission signals 47 and 57 are transmitted to the buffer circuits 44 and 54.
The outputs of the buffer circuits 44, 54 are directly transmitted to the constant current sources 41, 51 for controlling current supply, and the outputs of the constant current sources 41, 51 for controlling current supply control the current supply circuits 40, 50. By operating, it is possible to send out a response accommodation signal immediately responsive to the billing pulse sending signal _T1 as shown in the subscriber loop current LA2 in FIG. In addition, the charging pulse signal (T ₂
time), filter control switch 4
By opening signals 5 and 55 via the filter control signal terminal 60, charging pulse sending signals 47 and 5 are released.
7 connects filter sections 61 and 71, which are composed of constant current integration circuits 43 and 53 and CR integration circuits 42 and 52, each having a transfer function as shown by the solid line in FIG. Then, in order to drive the constant current sources 41 and 51 for current supply control that create the equivalent power supply for the current supply circuits 40 and 50, a smooth current change is applied to the subscriber terminal as shown in the subscriber loop current LA2 in FIG. A billing pulse signal can be sent out.

Next, when the supply current to the subscriber terminal is quickly cut off at time _T3 , the filter control switches 45 and 55 are closed via the filter control signal terminal 60 in the same manner as in the case of sending out the response storage signal described above. The charge pulse sending control signals 46, 56 are sent to the buffer circuits 44, 5 without passing through the buffer circuits 61, 71.
4 to drive the constant current source for current supply control, the current supply circuits 40, 50 accordingly supply the power supply current to the subscriber terminal as shown at _T3 of the subscriber loop current LA2 in FIG. It is possible to make a quick decision.

FIG. 6 shows a specific configuration of the embodiment. Buffer circuits 307, 407 include electronic switches 100, 200, resistors 101, 102, 103 and 201, 202, which are opened and closed by charging pulse sending control signals.
The voltage determined by 203 is applied to the operational amplifier 104, 2
04, and outputs it to the constant current integrating circuit 302 at the next stage of the operational amplifier 104, 204, as well as the constant current source 110, 1 of the constant current integrating circuit 302.
11, 210, and 211. Constant current integration circuits 302 and 402 are operational amplifiers 10
8,208, resistance 105,107,205,20
7. Integrating circuit composed of capacitors 106, 206 and constant current source 110, 1 driven by the integrating circuit
11, 210, 211, and a constant current integrating circuit with -V _BB /2 as a reference voltage, which is made up of capacitors 112, 212. Also, the next stage resistors 113, 11
4, 213, 214 and capacitors 115, 215 constitute CR integration circuits 303, 403 with −V _BB /2 as a reference voltage. And constant current integration circuit 30
2,402 and CR integration circuits 303,403 constitute filter sections 304,404. The filter sections 304, 404 are given by f(s) in response to a step signal input, as is well known, and have an output characteristic as shown by the dashed line in FIG. At time ₀ , the constant current circuit 110,
111, 210, 211 are buffer circuits 307,
407, it is saturated and output voltages as shown by the solid line in FIG. 5 are generated at V _A and V _B . The constant current section 305, 405 for current supply control is composed of an operational amplifier 116, 216, a resistor 117, 217, and a transistor 118, 218, and as is well known, changes in the voltage of the input V _A of the operational amplifier 116 and the input V _B of the operational amplifier 116 are controlled. The resistance 117,2
It has a function of converting into a current change divided by 17. In this example, voltage-current conversion is performed using operational amplifier 1.
16,216, but the resistor 11
It is also possible to configure it with only 7, 217 and transistors 118, 218. Therefore, the smoothly changing voltage shown by the solid line in FIG.
216 as the inputs V _A and V _B , the collector current changes of the transistors 118 and 218 of the current supply control constant current sections 305 and 405 also correspond to the voltage.
It changes smoothly like the change in V _A and V _B. The current supply units 306, 406 set the DC resistance values of the resistors 126, 127 and the DC resistance values of the resistors 226, 227 to be equal to _R1 , and use current mirrors 119, 219.
The mirror ratio of is a, the other current mirror 120,
Transistor 12 with a mirror ratio of 220 as b
4,224, operational amplifier 122,222, resistor 1
The amplification factor determined by 21, 123, 221, 223 is A, and the constant current section 305, 405 for controlling the current supply
The collector current of transistors 118 and 218 is
I ₀ , and the current I _L supplied by the current supply units 306 and 406 is R _e
Then, I _L =I ₀ · 2R ₁ /ab/2R ₁ /Aab+R _e .

From this, the constant current section 305, 4 for controlling the current supply
It can be seen that the output current I ₀ of 05 forms the equivalent power supply of the current supply units 306 and 406. Therefore, the constant current section 305, 4 for controlling the current supply as described above
If the output of 05 changes smoothly, the equivalent power supply of the current supply units 306, 406 changes smoothly, and accordingly, the power supply current I _L to the subscriber terminal also changes smoothly. By alternately operating this series of operations on the normal lever side as shown in the billing pulse sending signals 47 and 57 shown in _FIG . It becomes possible to send it to subscriber terminals.

Next, the filter control switch is electronic switch 10.
Consisting of 9,209 and 409,509,
The outputs of the buffer circuits 307, 407 and the inputs of the constant current section for controlling current supply are connected by electronic switches 109, 209 via resistors 114, 214. The filter control switch closes the electronic switches 109, 209 according to the filter control signal. Then, the output signals of buffer circuits 307 and 407 are
14, 214 and capacitors 115, 215 to the inputs of constant current sections 305, 405 for current supply control. The resistors 114, 214 and the capacitor 115,
If the time constant determined by
05,405, and the current supply unit 306,4
A step pulse current is supplied to 06. Therefore, since the current supply sections 306, 406 form the equivalent power supply as described above using step pulse currents, the current supplied from the current supply sections 306, 406 to the subscriber terminal also changes in a step manner. Then,
It is possible to send out the response accommodation signal shown at time T ₁ and the forced disconnection signal shown at time T ₃ of the subscriber loop current LA2. The filter control electronic switch is connected to the current supply control constant current section 305 through the resistors 114 and 214, so that the filter control electronic switch can withstand instantaneous charging and discharging of the capacitors 115 and 215. Urinal resistance 114, 21
4 may be omitted.

According to the present invention, as is clear from Fig. 6, since the intermediate potential between the earth's air and the battery is used as the reference voltage, the parts used can be constructed with low withstand voltages, making it easy to reduce the size and weight and enable electronicization. There are advantages,
It can be used in public billing pulse sending circuits such as automatic telephone exchanges.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a conventional billing pulse sending circuit, FIG. 2 is a time chart showing the operation of FIG. 1, FIG. 3 is a time chart showing the operation of the embodiment of the present invention, and FIG. A block diagram of a billing pulse sending circuit according to an embodiment of the invention, FIG. 5 shows the output waveform of the billing noise removal filter of the embodiment, and FIG.
FIG. 3 is a circuit diagram showing a specific example of the figure. 1...Subscriber terminal, 2...Subscriber line, 16,
17,304,404...Filter section, 40,5
0,306,406...Current supply section, 301...
Battery, 41, 51, 305, 405... Constant current section for current supply control, 45, 55, 109, 209,
409,509...Filter control switch, 4
4, 54, 307, 407... buffer circuit, 4
6,56,100,200,400,500...
Charging pulse sending control terminal, 60...Control terminal for filter control switch.

Claims (1)

[Claims] 1. Consists of a constant current integrator circuit and a CR integrator circuit provided on the earth air side and the battery side, respectively, with charging pulses as input control signals for sending out, and intermediate potential between earth air and battery as virtual ground. a filter unit for controlling the current supply, which takes the output of the filter unit as input and uses the intermediate potential between the ground air and the battery as a virtual ground, and is provided on the ground air side and the battery side, respectively, and generates a current signal for current supply control. a current section, and an equivalent power supply current source connected between the pair of subscriber lines and the earth/battery and proportional to the output signal of the constant current section for current supply control, which supplies current through the subscriber line. The subscriber terminal has two circuits each consisting of a unidirectional current supply section using a current mirror that supplies the subscriber terminal to the subscriber terminal, and the subscriber line connection polarities of the current supply sections are connected so that they are opposite to each other. A public billing pulse sending circuit featuring the following features: 2. A filter section configured of a constant current integrator circuit and a CR integrator circuit provided on the earth air side and the battery side, respectively, which inputs a control signal for sending billing pulses and uses an intermediate potential between the earth air and the battery as a virtual ground; a constant current section for current supply control that receives the output of the section as an input and generates a current signal for controlling the current supply provided on the ground air side and the battery side, respectively, with the intermediate potential between the ground air and the battery as a virtual ground; a current mirror connected between the subscriber line and the earth/battery and supplying current to the subscriber terminal via the subscriber line with an equivalent power supply current source proportional to the output signal of the current supply control constant current section; and a filter control switch that can be opened and closed by a control signal between the input of the constant current integration circuit and a terminal in the CR integration circuit, and when the filter control switch is closed, the A constant current unit for current supply control is driven by the sum of the output signal of the constant current integration circuit and the billing pulse sending control signal, and the current supplying unit supplies the current to the subscriber terminal based on the billing pulse sending control signal. 1. A charging pulse sending circuit for public use, comprising two circuits capable of quickly cutting off and quickly supplying current, and connected so that the subscriber line connection polarities of the current supply sections are opposite to each other.