JP2000184101A - System and method for changing-over normal and reverse power feeding in time compression multiplexing transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a device capable of changing-over noiseless normal and reverse power feeding with a simple circuit configuration by turning-off power feeding to a subscriber's line and changing-over normal and reverse power feeding during the power feeding off-period. SOLUTION: The soft start control signal of a relay control part 5 is turned off, a soft start relay 2 is released and a subscriber power feeding power source 3 is separated from the subscriber's line 6. During the stop of power feeding to the line 6, the normal/reverse changing-over signal of the relay control circuit 5 is turned off or on, a normal/reverse change-over relay 1 is changed-over to a normal or reverse side, the soft start control signal is turned on again and the soft start relay 2 is closed. Thus, the subscriber power feeding source 3 is connected to the subscriber's like 6 so that power feeding in a normal mode or a reverse mode is enabled. Data of a data exchanging part 4 is superimposed in the reverse mode to attain communication.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a normal and reverse power supply switching system and a switching method in a ping-pong transmission system, and more particularly to a DSU which is a lower-level device via a subscriber line when controlling outgoing / incoming calls in the ping-pong transmission system.
The present invention relates to a power supply switching system that performs normal and reverse power supply switching control when performing station power supply to a (Digital Service Unit).

[0002]

2. Description of the Related Art FIG. 3 is a diagram for explaining this kind of conventional power supply switching system. In FIG. 3, subscriber line 6
Is composed of a pair of metallic lines L 1 and L 2, and a DSU (not shown), which is a lower-level device, is connected to the ends of the pair of metallic lines L 1 and L 2. It is connected to the. The power supply 3 is a power supply for subscriber power supply having a positive polarity potential and a negative polarity potential for performing normal power supply or reverse power supply.

The power supply relay 7 is for normal power supply to a DSU (not shown), and the power supply relay 8 is for reverse power supply. The control of the power supply relay 7 is controlled by a NOR (normal) power supply control signal from the relay control unit 9, and the control of the power supply relay 8 is controlled by the REV from the relay control unit 9.
It is controlled by a (reverse) power supply control signal. In addition, a data transmission / reception unit 4 is provided for performing communication with the DSU by superimposing data during reverse power feeding.

In such a configuration, at the time of normal power supply, the NOR power supply control signal from the relay control unit 9 is activated and the relay 7 is closed, so that the subscriber power supply 3 is switched to the subscriber DSU by the positive power supply (normal mode).
Power supply to At the time of reverse power supply, the REV power supply control signal from the relay control unit 9 is activated and the relay 8 is closed to supply power to the subscriber DSU with the reverse power supply (reverse mode) and to supply data to the subscriber DSU. The communication is performed by superimposing the data of the transmission / reception unit 4.

[0005]

The problem with the prior art described above is that it is necessary to add a special function circuit to realize the soft start function at the time of power supply switching, which increases the cost. It is. In other words, when the polarity is switched from normal power supply to reverse power supply and vice versa from reverse power supply to normal power supply, there is a sudden change in current, which becomes a noise source and adversely affects adjacent lines during communication, and This will cause an error.

In order to avoid this, the operation speed can be reduced by reducing the control current of each of the relays on the normal power supply side and the reverse power supply side. A sudden change in current generated at the time of switching is suppressed so as not to be a noise source. However, the photo MOS relay with the software function is expensive, and if it is used on both the normal power supply side and the reverse power supply side, the circuit configuration becomes expensive.

An object of the present invention is to provide a normal and reverse power supply switching system and a switching method in a ping-pong transmission system which can be realized with an inexpensive circuit configuration.

[0008]

According to the present invention, there is provided a power supply switching system for controlling switching between normal and reverse power supply to a lower-level device via a subscriber line during call origination and termination control in a ping-pong transmission system. A power supply switching system comprising: power supply off control means for turning off power supply to the subscriber line; and power supply switching means for switching between the normal / reverse power supply during the power supply off period. can get.

The subscriber line has a pair of metallic lines, and the power supply switching means connects one of the pair of metallic lines to the positive polarity of the power supply and the other to the negative polarity during the normal power supply. A relay for switching one of the pair of metallic wires to the negative polarity of the power supply and the other to the positive polarity at the time of the reverse power supply, and the power supply off control means includes a pair of the metallic wires. And a relay for disconnecting the power supply from the power supply. Further, the power supply off control means is a relay having a soft start function.

According to the present invention, there is provided a power supply switching method for performing a normal / reverse power supply switching control to a lower-order device via a subscriber line during an outgoing / incoming call control in a ping-pong transmission system. Power supply switching comprising: a first step of turning off power supply to a line by a relay having a soft start function; and a second step of switching the normal / reverse power supply during the power supply off period. A method is obtained. Further, a third step of turning on the power supply to the subscriber line by a relay having a soft start function after the second step is provided.

The operation of the present invention will be described. The state of power supply to the subscriber line is controlled in advance by a relay having a soft start function, and in this power supply off state, switching control of normal / reverse power supply is performed so that a sharp current at the time of polarity change is obtained. I try to eliminate the change.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention, and the same parts as those in FIG. 3 are denoted by the same reference numerals. A soft start (photo mos) relay 2 for turning off the power supply output of the power supply 3 is provided.
A normal / reverse switching relay 1 is provided on the subscriber side (DSU) of the relay 2.

The relay control section 5 generates a soft start control signal and a real / reverse switching signal. The relay 1 is controlled by a normal / reverse switching signal, and the relay 2 is controlled by a soft start control signal. The other configuration is the same as that of FIG.

FIG. 2 is an example of a timing chart showing the operation of the circuit of FIG. At the time of switching from reverse power supply to normal power supply (see FIG. 2A), first, the soft start signal of the relay control unit 5 is turned off to release the soft start relay 2, and the subscriber power supply 3 is switched to the subscriber power supply. Disconnect from line 6. While the power supply to the subscriber line 6 is stopped, the normal / reverse switching signal of the relay control unit 5 is turned off, the normal / reverse switching relay 1 is switched to the normal side, and the soft start control signal is turned on again. Then, the soft start relay 2 is closed. This allows
The subscriber power supply 3 is connected to the subscriber line 6, and power can be supplied in the normal mode.

At the time of switching from the normal power supply to the reverse power supply (see FIG. 2B), similarly to the above, the soft start signal of the relay control unit 5 is turned off to release the soft start relay 2 and the subscriber power supply. The power supply 3 is disconnected from the subscriber line 6. While the power supply to the subscriber line 6 is stopped, the normal / reverse switching signal of the relay control unit 5 is turned on, the normal / reverse switching relay 1 is switched to the reverse side, and the soft start control signal is turned on again. Then, the soft start relay 2 is closed. This allows
The subscriber power supply 3 is connected to the subscriber line 6 to enable power supply in the reverse mode. In this reverse mode, communication is performed by superimposing data from the data transmitting / receiving unit 4. Become.

As shown in the current change charts of FIGS. 2A and 2B, when the soft start relay 2 is turned on / off, only a gradual change in the current occurs, and a sharp change in the current occurs. Does not occur.

[0017]

As described above, according to the present invention, when switching between normal power supply and reverse power supply, power supply is performed in an off state, and normal / reverse power supply switching control and power supply power on / off control are performed. Since the configuration is such that the functions are controlled separately, there is an effect that a normal and reverse power supply switching method without noise can be obtained with a simple circuit configuration.

[Brief description of the drawings]

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

FIG. 2 is an example of a timing chart illustrating an operation of the exemplary embodiment of the present invention.

FIG. 3 is a diagram for explaining a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Normal / reverse switching relay 2 Soft start relay 3 Power supply for subscriber power 4 Data transmission / reception section 5 Relay control section 6 Subscriber line

Claims (7)

[Claims] 1. A power supply switching system for performing a normal / reverse power supply switching control to a subordinate device via a subscriber line at the time of outgoing / incoming call control in a ping-pong transmission system, wherein power is supplied to the subscriber line. Power-off control means for turning off the power supply;
A power supply switching system comprising: a power supply switching unit that performs reverse power supply switching. 2. The subscriber line has a pair of metallic lines, and the power supply switching means connects one of the pair of metallic lines to a positive polarity of a power supply and the other to a negative polarity during the normal power supply. 2. The power supply switching system according to claim 1, further comprising a relay for switching one of the pair of metallic wires to a negative polarity of the power source and the other to a positive polarity during the reverse power supply. 3. The power supply switching system according to claim 2, wherein the power supply off control means includes a relay for disconnecting the pair of metallic wires from the power supply. 4. The power supply off control means is a relay having a soft start function.
4. The power supply switching system according to any one of to 3 above. 5. A power supply switching method for performing normal / reverse power supply switching control to a lower-order device via a subscriber line during outgoing / incoming call control in a ping-pong transmission system, wherein power is supplied to the subscriber line. And a second step of switching the normal / reverse power supply during the power supply off period. 6. The power supply switching method according to claim 5, further comprising a third step of turning on power supply to the subscriber line after the second step. 7. The power supply switching method according to claim 6, wherein the power supply on / off in the first and third steps is performed by a relay having a soft start function.