JPS60260268A - Subscriber circuit feeding system - Google Patents

Abstract

PURPOSE:To attain miniaturization of a subscriber circuit subject to low power consumption by providing a DC/AC converting means in common and providing an AC/DC means at each subscriber circuit. CONSTITUTION:A DC voltage of -48V from an exchange main power supply is inputted to a DC/AC converting circuit 5, and an AC voltage is generated in the secondary winding of a transformer T and fed to plural subscriber circuits 21 via a bus 6. The AC voltage is inputted to an AC/DC converting circuit 7 in each subscriber circuit 21, and after the voltage is rectified in full wave by a full wave rectifier RF, it is smoothed, converted into a DC voltage and fed to a talking current supply circuit 31 so as to apply the talking current to the subscriber lines L1, L2. Since the talking current supply DC voltage fed to the circuit 31 is set to apply the same talking current to the subscriber terminal equipment when the total value of the line resistor and the subscriber terminal of the subscriber lines L1, L2 is equal, the power consumed in the circuit 31 is almost halved.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a subscriber circuit, and more particularly to a subscriber circuit power supply system that reduces power consumption and downsizes the subscriber circuit.

(bl Background of the Technology In digital exchanges, it is impossible to supply call current to subscribers via the call path network, so it is necessary to provide a call current supply means in the subscriber circuit that accommodates each subscriber terminal. There is.

(0) Prior Art and Problems FIG. 1 is a diagram showing an example of a conventional subscriber circuit power supply system for this type of subscriber circuit. In FIG.
The current is supplied to the communication current supply circuit 3. The communication current supply circuit 3 supplies power to the subscriber line L1 via a series circuit of a transistor Q1 and a resistor R1, and to the subscriber line L2 via a series circuit of a transistor Q2 and a resistor R2.
The communication current is supplied from the exchange main power supply l. Control circuit CT
L is the defined array circuit for supplying a communication current of a predetermined current value to a subscriber terminal accommodated via a subscriber line having a line resistance within an allowable range (for example, 1500 ohms or less). Control is performed so that the internal resistance of each is 220 ohms.

As is clear from the above explanation, the conventional subscriber circuit power supply system is a so-called constant resistor system that supplies the communication current from the exchange main power supply 1 to the subscriber terminal via the communication current supply circuit 3 having an internal resistance of 440 ohms. This is a power supply method. Therefore, in addition to the power consumed by the resistances of the subscriber lines L1 and L2, power is also consumed by the internal resistance of the communication current supply circuit 3.

The power consumed in this call current supply circuit 3 increases to several watts, especially for subscriber terminals with the shortest subscriber lines L1 and L2, and the subscriber circuit 2 is required to be miniaturized and highly integrated. cause hindrance. In order to eliminate this cause, each subscriber circuit 2 is provided with a switching power supply type communication current supply circuit, and the DC voltage of 148 volts supplied from the main power supply 1 of the exchange is once converted to AC by a DC/AC conversion circuit.
Attempts have been made to reduce the power consumption in the subscriber circuit 2 by converting the DC voltage into a DC voltage suitable for supplying a predetermined communication current to the subscriber terminal using an AC/DC conversion circuit. However, since such a switching power supply system is composed of large components such as a transformer, it has the disadvantage that it impairs the miniaturization of each subscriber circuit.

(dl) Purpose of the Invention An object of the present invention is to eliminate the drawbacks of the conventional subscriber circuit power supply system as described above, and to realize a compact subscriber circuit with low power consumption.

tel Structure of the Invention It is an object of the present invention to provide a DC/AC conversion means for converting direct current supplied from a main power source of an exchange into alternating current and supplying the converted current to a plurality of subscriber circuits in a subscriber circuit that supplies communication current to subscriber terminals. This is achieved by providing each subscriber circuit with AC/DC converting means which is provided in the plurality of subscriber circuits 21 and converts the alternating current supplied from the DC/AC converting means into direct current for supplying communication current to the subscriber terminals. be done.

ff) Examples of the invention An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram showing a subscriber circuit power supply system according to an embodiment of the present invention. Note that the same reference numerals indicate the same objects throughout the figures. In FIG. 2, a DC/AC converter circuit 5 is provided in common for a plurality of subscriber circuits 21, and each subscriber circuit 21 is provided with an AC/DC converter circuit 7, respectively. Furthermore, the communication current supply circuit 31 provided in each subscriber circuit 21 includes an internal resistance having a lower resistance value than that of the communication current supply circuit 3 in FIG. The resistance values of the series circuit of Q2° and resistor R2' are each set to 100 ohms. In FIG. 2, a DC voltage of 148 volts supplied from the exchange main power supply 1 is input to a DC/AC conversion circuit 5. In FIG. In the DC/AC conversion circuit 5, drivers DVI and DV2 switch transistors Q3 and Q4 at a predetermined period (for example, 128 kHz).
are alternately rendered conductive, and the polarity of the 148 volt DC voltage applied to the primary stirring wire of the transformer T is reversed at the predetermined period. As a result, the AC voltage generated in the secondary winding of the transformer T has its harmonics removed by the low-pass filter LPF 1, and is then supplied to the plurality of subscriber circuits 21 via the power supply lotus 6. . In each subscriber circuit 21, the AC voltage supplied from the power supply bus 6 is inputted to the AC/DC converter circuit 7, where it is full-wave rectified by the full-wave rectifier RF, and then passed through the low-pass filter LPF2. is converted into DC voltage,
It is supplied to the communication current supply circuit 31 as a direct current for supplying communication current. The communication current supply circuit 31 has a low resistance value (
The communication current is supplied to each subscriber line L1 and L2 via an internal resistance (according to the example, 200 ohms). Note that the DC voltage for communication current supply supplied from the AC/DC converter circuit 7 to the communication current supply circuit 31 is equal to the total value of the line resistance of the subscriber lines L1 and L2 and the internal resistance of the subscriber terminal. The setting is such that the same communication current as shown in the figure can be supplied to the subscriber terminal. As a result, the power consumed within the communication current supply circuit 31 is reduced by about half compared to that in FIG.

As is clear from the above description, according to this embodiment, the DC/AC converter circuit 5 is constructed of large components such as the transformer T.
is provided in common to a plurality of subscriber circuits 21, so each subscriber circuit 21 can be miniaturized.

It should be noted that FIG. 2 is only one embodiment of the present invention, and for example, the DC/AC converter circuit 5 is not limited to being provided in one set for the main power supply 1 of the exchanger, and may be, for example, provided on one printed board. Many other modifications may be considered, such as providing the DC/AC converter circuit 5 in common to the eight subscriber circuits mounted within the system, but the effects of the present invention will not change in any case. Further, the subscriber circuit 21 is not limited to supplying a communication current to the subscriber terminal by inputting the communication current supplying DC output from the AC/DC converter circuit 7 into the communication current supply circuit 31; Although it is also possible to directly supply the direct current for supplying communication current output from the conversion circuit 7 to the subscriber lines L1 and L2, the effects of the present invention do not change even in such a case.

Tg) Effects of the Invention As described above, according to the present invention, it is possible to realize a small subscriber circuit with low power consumption.

[Brief explanation of drawings]

Figure 1 is a diagram showing an example of a conventional subscriber circuit power supply system.
FIG. 2 is a diagram showing a subscriber circuit power supply system according to an embodiment of the present invention. In the figure, l is the exchange main power supply, 2 and 21 are subscriber circuits, 3 and 31 are call current supply circuits, 4 is a voice termination circuit, 5 is a DC/AC conversion circuit, 6 is a power supply bus, and 7 is an AC/DC conversion circuit. The circuit, CTL, is the control circuit, DVI and D
V2 is a driver, LPF1 and LPF2 are low-pass filters, Q1 to Q4 are transistors, R1 and R2 are resistors, RF is a full-wave rectifier, and T is a transformer.

Claims (1)

[Claims] In the subscriber circuit that supplies telephone current to the subscriber terminal,
The plurality of subscriber circuits are provided with a DC/AC conversion means that converts the DC supplied from the exchange main power source into AC and supplies the converted AC to the plurality of subscriber circuits, and the AC supplied from the DC/AC conversion means is provided in common with the plurality of subscriber circuits. A subscriber circuit power feeding system, characterized in that each subscriber circuit is provided with an AC/DC converter for converting into a direct current for supplying communication current to the subscriber terminals.