JPS598461A - Metering pulse transmitting circuit - Google Patents

Abstract

PURPOSE:To simplify a filter of metering pulse transmission circuit, by bringing an electronic DC current supply circuit to high impedance in terms of AC. CONSTITUTION:The DC current supply circuit 201 brought to a high impedance by a capacitor 203 supplies DC in the normal direction to a subscriber register 1 and the DC current supply circuit 202 brought to a high impedance by a capacitor 204 supplies a DC in the reverse direction to a resistor 1. Further, a transistors 106, 109, 116, 119 are controlled for on/off at the transmission of a metering pulse. An input current waveform, in this case, to a filter comprising coils 2, 3 and a capacitor 6 is a waveform showing charge/discharge by forming an equivalent inductance by capacitors 203, 204 as the whole DC current supply circuit, and it is equivalent to be passed through one stage of an LPF.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a billing pulse sending circuit for a public subscriber circuit of a time division exchange.

A conventional billing pulse sending circuit is composed of a relay, a coil, and a capacitor, and therefore occupies a large volume in terms of packaging, and the cost of each element is high, making it uneconomical.

This will be specifically explained using FIG. 1. In FIG. 1, 1 is the resistance of the subscriber line (including the terminal), 2, 5 . A,
5 is a filter coil (inductor), 6 and 7 are filter capacitors, 8゜9 is a relay contact for cutting off the current, 10.11 is a relay contact for reversing the current, 12 is a loop A detection relay (AC low impedance), 16 is a local power source. Referring to FIG. 1, the transmission of billing pulses related to the present invention will be explained.

The charging pulse first operates relay contacts 8 and 9 to cut off the DC current, and after timing, relay contacts 10.
Operate 11 and flow the reversed t flow. After taking appropriate timing, relay contacts 10.11 are moved back to cut off the DC current, and after timing, relay contacts 10.11 are moved back to allow normal DC current to flow and generate billing pulses. Sending is finished. The control signals and current waveforms at this time are shown in ◯, ◯, and ◯ in Fig. 4. As shown in ■ in Figure 4, the input current to the filter (consisting of coils 2, 3, 4.5 and capacitors 6 and 7 in Figure 1) is approximately a rectangular wave, so the audio This becomes noise in the band and must be removed by a filter. This filter is called a billing filter, and in order to sufficiently suppress noise, a filter with a large coil and two stages of capacitors is required as shown in FIG. For this reason, it occupies a large volume in terms of packaging, and the cost of each element is high (there is a problem in economic efficiency).

On the other hand, a circuit configuration has been proposed in which the relay contacts 8.9 and 10.11 and the relay 12 are replaced with electronic circuits. An example of this circuit is shown in FIG. In Fig. 2, the same parts as in Fig. 1 are given the same numbers, 101 is a circuit for supplying direct current to the current in the normal direction, and 102 is a DC current to the current in the reverse direction. Current supply circuit (101, 102
The isometric DC resistance is the same as relay 12 in Figure 1), 1
03, 104'.

105.107,108,110,111,112 and 113,114,115°117.118,120,1
21, 122 are transistors and resistors for realizing isometric direct current resistance, and 106, 109, 116° and 119 are transistors for controlling on/off of the direct current supply circuit. In FIG. 2, transistors 106, 109
, 116, 119 are shown in ■ in Figure 4.

If controlled to 5 as shown in ■, all (similar characteristics) as in Fig.
(corresponding to ■) is obtained. King Shikatsu.

The part where the relay is replaced by an electronic circuit is miniaturized.

However, since a filter portion similar to that shown in FIG. 1 is still required, it is large in terms of implementation and occupies a large proportion in terms of cost.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a small and economical charging pulse sending circuit.

The present invention improves the current supply circuit, which is made up of an electronic circuit, by making it have a high AC impedance (equivalent inductance) and using the equivalent inductance as part of the filter of the billing pulse sending circuit. , which simplifies the conventional billing pulse sending circuit filter.

A specific embodiment of the present invention will be described using FIG. 6. Third
In the figure, the same parts as in Figures 1 and 2 are given the same numbers, 201 is a DC current supply circuit with a high impedance current for normal direction calculation, and 202 is a DC current supply circuit in the reverse direction. 203 and 204 are capacitors for increasing the impedance. In the third prisoner, when transmitting the charging pulse, the transistors 106, 109, 11
<S.

119 may be controlled as shown in (1) and (2) in FIG.

In that case, the waveform of the current input to the filter (coils 2 and 3 and capacitor 6) and C is such that the capacitors 205 and 204 form an equivalent inductance as a whole of the DC current supply circuit, and the waveform of the current is as shown in Figure 4 (■). This becomes a discharge waveform, which is equivalent to passing through one stage of low-pass filter. Therefore, since the charging noise in the voice band is completely suppressed at the input of the charging filter, a two-stage filter consisting of a coil and a capacitor as shown in Fig. 1, and a coil and capacitor as shown in Fig. 3 are used. It is possible to achieve the same level of billing noise suppression even with a single-stage filter. In addition, the capacitors 203 and 204 that make the DC current supply circuit high impedance (provide equivalent inductance) are 105, 107, 108, 110, 1
By appropriately selecting circuit constants such as 15,117°118.120, it is possible to reduce the capacity, and it is easy to implement.
There is almost no increase in cost.

As described above, according to the present invention, the billing filter for sending out one billing pulse can be simplified, the packaging can be made smaller, and the number of coils and large-capacity capacitors, which account for a large proportion of the cost, can be reduced. An economical billing pulse sending circuit can be realized.

[Brief Description of the Drawings] Fig. 1 shows a conventional charging pulse sending circuit, Fig. 2 shows a charging pulse sending circuit in which the relay in the conventional example of Fig. 1 is replaced with an electronic circuit, and Fig. 5 4 is a diagram showing a billing pulse sending circuit according to an embodiment of the present invention, and FIG. 4 is a diagram showing waveforms of the billing pulse sending control signal and filter input current in FIGS. 1 to 3. 1...Resistance of subscribed line (including terminals) 2, 3, 4.5
... Filter coil 6.7.・Filter capacitor 15... Station power supply 201... DC current supply circuit 202 with high impedance direct current in the normal direction... DC current supply circuit 105 with high impedance current in the reverse direction .106,109,111.115,116,1
19. '121...Transistor 104.105,107,108,110,112,1
14,115,117,118°120, 122...
・Resistance 203.204... High impedance capacitor 3 Figure 2 ρ7? 4 - Continuation of figure 1 page ■Applicant: Oki Electric Industry Co., Ltd., 1-7-12 Toranomon, Minato-ku, Tokyo ■Applicant: NEC Corporation, 5-33-1 Shiba, Minato-ku, Tokyo ■Applicant: People Fujitsu Ltd. 1015 Kamiodanaka, Nakahara-ku, Kawasaki City

Claims (1)

[Claims] In a public subscriber circuit that has a function of sending billing pulses to a subscriber line, a DC current supply circuit that switches and supplies DC currents of different polarities is configured with an electronic switching circuit, and the DC current supply circuit has an equivalent inductance. A billing pulse sending circuit characterized in that a billing filter is configured by a capacitor and a coil connected to the equivalent inductance and a subscriber line.