JPH03117097A - Two-wire/four-wire converter - Google Patents

Abstract

PURPOSE:To facilitate the design of a potential separation transformer, and also, to miniaturize the shape by allowing a two-wire/four-wire converting circuit to receive directly feed from a floating type DC current, connecting directly a two-wire line to a two-wire terminal of the two-wire/four-wire converting circuit, and connecting the potential separation transformer to a four-wire input/output terminal of the two- wire/four-wire converting circuit. CONSTITUTION:In the two-wire/four-wire converter which contains a feeding circuit 3 for feeding to a two-wire line L2 from a floating type DC power source 2, and a two-wire/four-wire converting circuit 6 which is connected to the two-wire line L2 and executes a two-wire/four-wire conversion, two-wire side terminals T1, T2 of the two-wire/four-wire converting circuit 6 are connected directly to the two-wire line L2, transformers 5S, 5R are connected to four-wire side input/output terminals of the two-wire/four-wire converting circuit 6, respectively, and also, a circuit current of the two-wire/four-wire converting circuit 6 is supplied from the floating type DC power source 2. In such a way, a DC stopping capacitor is omitted, and also, with respect to an insulation transformer for a potential separation, it is unnecessary to consider saturation due to a fact that a DC flows, the design of a transformer is facilitated, and also, the whole device can be miniaturized by miniaturizing a shape of the insulation transformer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a 2-wire/4-wire converter, and particularly to a 2-/4-wire converter that can bring a potential separation transformer closer to an ideal transformer.

[Conventional technology]

Generally, two-line and four-line conversion devices are used in carrier devices connected to subscriber lines and trunk lines of telephone exchanges.

An example of such a two-wire and four-wire converter is shown in FIG.

The 2-wire 4-wire converter 11 shown in FIG. 2 includes a floating DC power supply 12 isolated from other potentials, and a floating DC power supply
2, and terminals 'r,..., T,
A power supply circuit 13 that supplies power to the two-wire line L2 via the
and the terminals Tz, T to which this two-wire line L2 is connected.
+□ DC blocking capacitor 14 and isolation transformer 15
The circuit includes a 2-wire/4-wire conversion circuit 16 which is connected via a 2-wire/4-wire conversion circuit 16 and performs 2-wire/4-wire conversion. Here, the 2-wire 4-wire conversion circuit 16 has a 2-wire terminal W2 and a 4-wire terminal W S 4 .
WR4, the secondary winding of the isolation transformer 15 is connected to the 2-wire terminal W2, and the terminal TI is connected to the 4-wire terminal WS4.
3. The transmission side line of the 4-wire line is connected to the 4-wire terminal WR, via the terminal TI5. 4 via T16
The receiving side lines of the wire line are connected to each other.

The signal from the two-wire line L2 is sent to the terminals T II, I
I2, direct current blocking capacitor 14, taken into the 2-wire 4-wire conversion circuit 16 via the isolation transformer 15, converted into 2-wire 4-wire in the 2-wire 4-wire conversion circuit 16, and connected to the terminal T to the 4-wire terminal WS4. It is sent out to the transmitting line of the four-wire line via T,4. In addition, the signal sent via the receiving side line of the 4-wire line is taken into the 2-wire 4-wire conversion circuit 16 via the terminal T15°T, 6, and the 2-wire 4-wire conversion circuit 16 converts the signal to the 4-wire The signal is converted into two wires and sent to a two-wire line L2 via an isolation transformer 15, a capacitor 14, and terminals T, , T, and □.

At this time, from the power supply circuit 13 which is insulated from the earth
Direct current is supplied to the wire line L2. Here, II and I2 indicate charging and discharging currents flowing into the DC blocking capacitor 14. In addition, as mentioned above, the reason for insulating from earth resistance is that the two-wire line L2 may be pulled outdoors or placed in the same cable duct as the commercial AC power cable, which may lead to the induction of AC noise. This is because there is a need to improve AC noise induction resistance.

[Problem to be solved by the invention]

According to the conventional 2-wire 4-wire converter 11 described above, as shown in FIG. 2, since the DC blocking capacitor 14 and the isolation transformer 15 are connected to the 2-wire line L2, charging of the feeding polarity reversal method is possible. Each time a signal is sent to the two-wire line L2, the charging and discharging current for the DC blocking capacitor 14 flows to the isolation transformer 15 for potential separation when the polarity is reversed.

Due to this charging/discharging current, the isolation transformer 15 becomes saturated,
The audio signal being transmitted may be interrupted.

Therefore, the inductance of the isolation transformer 15 needs to be suppressed so as not to be saturated by the charging/discharging current. on the other hand,
In order to satisfy the mismatch attenuation standard for the 2-wire/4-wire converter 11, it is necessary to increase the inductance of the isolation transformer 15 to bring it closer to an ideal transformer. In order to satisfy these conflicting demands, the isolation transformer 15
It was necessary to make the shape several times larger than the normal size, and the disadvantage was that the circuit could not be miniaturized.

The present invention has been made in order to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a 2-wire 4-wire conversion device that can bring a potential separation transformer close to an ideal transformer.

[Means to solve the problem]

The 2-wire 4-wire conversion device of the present invention includes a power supply circuit that supplies power to a 2-wire line from a floating DC power supply isolated from other potentials;
In a 2-wire 4-wire conversion device that includes a 2-wire 4-wire conversion circuit that is connected to a wire line and performs 2-wire 4-wire conversion, the 2-wire side terminal of the 2-wire 4-wire conversion circuit is directly connected to the 2-wire line. , a transformer is connected to each of the input/output terminals on the 4-wire side of the 2-wire 4-wire conversion circuit, and the circuit power supply of the 2-wire 4-wire conversion circuit is supplied from a floating DC power supply. .

The present invention simplifies transformer design by omitting a DC blocking capacitor and eliminating the need to consider saturation due to the flow of DC with respect to an isolation transformer for potential separation. This makes it possible to reduce the size of the device.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

The 2-wire 4-wire converter 1 shown in FIG. A power supply circuit 3 that supplies power to the wire line L2, and a two-wire line L2
Terminal T1, to which is connected.

A 2-wire 4-wire conversion circuit 6 that connects 'I''+2 directly to the 2-wire side terminal W2, receives power from the floating DC power supply 2, and performs 2-wire 4-wire conversion, and a 2-wire 4-wire conversion circuit. 6
4-wire side input/output terminal WS4. It is configured to include isolation transformers 5s and 5R respectively connected to WR4.

In addition, the secondary winding of the isolation transformer 5s has a terminal T3.
, the transmitting line of the 4-wire line is connected to the secondary winding of the 4-wire isolation transformer 5R via T 4 , and the receiving line of the 4-wire line is connected to the secondary winding of the 4-wire isolation transformer 5R via terminals Ts and Ts , respectively. .

The operation of such an embodiment will be explained.

The signal from the 2-wire line L2 is taken into the 2-wire/4-wire conversion circuit 6 via the terminals T, , T2, converted to 2-wire/4-wire, and converted into a 4-wire signal.
From wire terminal WS4 to insulation transformer 53, terminal T, 3.
It is sent out to the transmitting line of the 4-wire line via T I 4. In addition, the signal sent via the receiving side line of the 4-wire line is taken into the 2-wire 4-wire conversion circuit 6 via the isolation transformer 5R, converted into 4-wire and 2-wire, and sent to the terminals T + and T.
2 to the two-wire line L2.

The electronic 2-wire 4-wire conversion circuit 6 receives power consumption from the floating DC power supply 2, so unlike conventional devices, the 2-wire 4-wire conversion circuit 6 is connected to the 2-wire line via an isolation transformer and a DC blocking capacitor. Since there is no need to connect to L2 and it can be directly connected to the two-wire line L2, there is no need to consider saturation due to current flowing through the isolation transformer. In addition, the isolation transformers 5S and 5R are the 2-wire 4-wire conversion circuit 6.
4-wire side input/output terminal WS4. Connected to WR4. 2
The DC component flowing through the wire line L2 is blocked within the 2-wire/4-wire conversion circuit 6, and is passed through the 4-wire side input/output terminal WS4. of the 2-wire/4-wire conversion circuit 6. Since it is not output to WR4,
Isolation transformer 5s, 5. In this case, only audio signals need to be handled.

Therefore, the isolation transformer 5s, 5. Since no direct current flows through the circuit, it is only necessary to design the system in consideration of audio signals, and the isolation transformer can be made smaller. Even if two isolation transformers are required per circuit, the entire device can be made smaller. In addition, when designing the isolation transformer 55°5R, the inductance limit that was considered to prevent saturation due to DC current is removed, so the inductance can be designed to be high, and the isolation transformer 5. ．． By bringing 5R closer to the ideal transformer, the mismatch attenuation characteristics and echo attenuation characteristics, which are audio characteristics, are improved.

〔Effect of the invention〕

As described above, the present invention allows a 2-wire 4-wire conversion circuit to receive power directly from a floating DC power source, and converts a 2-wire line into a 2-wire 4-wire converter circuit.
Since it is directly connected to the 2-wire terminal of the line conversion circuit, and the potential separation transformer is connected to the 4-wire input/output terminal of the 2-wire 4-wire conversion circuit, there is no need to consider that a DC component flows through the potential separation transformer. This has the effect that the design of the transformer is facilitated, and the shape of the transformer can be made smaller, so that the entire device can be made smaller.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a two-wire converter according to the present invention, and FIG. 2 is a circuit diagram showing a conventional two-wire/four-wire converter. 1... 2-wire 4-wire converter, 2... Floating DC power supply, 3... Power supply circuit, 5S, 5R... Insulation transformer, 6... ...
...2-wire 4-wire conversion circuit.

Claims (1)

[Claims] A 2-wire 4-wire power supply circuit that supplies power to a 2-wire line from a floating DC power supply isolated from other potentials, and a 2-wire 4-wire conversion circuit that is connected to the 2-wire line and performs 2-wire 4-wire conversion. In the conversion device, the 2-wire side terminal of the 2-wire 4-wire conversion circuit is connected to 2 wires.
A configuration in which a transformer is connected directly to a wire line, a transformer is connected to each of the 4-wire side input/output terminals of the 2-wire 4-wire conversion circuit, and circuit power for the 2-wire 4-wire conversion circuit is supplied from the floating DC power supply. A 2-wire and 4-wire conversion device characterized by: