JPH05191318A - Transmission terminal equipment of transmission line feeding system - Google Patents

Abstract

PURPOSE:To surely discriminate a transmission signal (current) of a transmission terminal equipment, load fluctuation of the transmission terminal equipment and a charge current of a power supply section and to make a power supply voltage of the transmission terminal equipment by suppressing the fluctuation in the power supply voltage of the transmission terminal equipment in the transmission system in which the transmission terminal equipment receives feeding through a transmission line. CONSTITUTION:A control section 27 of a transmission terminal equipment 4A discriminates the polarity of a line based on a potential at a connecting point between a diode 28 and a resistor 29, and a current limiting circuit 30 is used to apply a current limit in matching with its own steady-current when the polarity of a transmission power supply is a polarity required for detecting a change of a transmission code '1' to '0'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a transmission power source, a transmission line,
The present invention relates to a transmission line feed type transmission terminal device in a transmission system including a transmission terminal device.

[0002]

2. Description of the Related Art The structure of a conventional transmission system is shown in FIGS.
Also, description will be made with reference to FIG. FIG. 4 is a block diagram showing a conventional transmission system using a transmission terminal, and FIGS. 5 and 6 are block diagrams and circuit diagrams showing a conventional transmission power source.

In FIG. 4, 1 is an AC power supply, 2 is a transmission power supply connected to the AC power supply 1, 3a and 3b are transmission lines connected to the transmission power supply 2, and 4 is a connection to these transmission lines 3a and 3b. It is a transmission terminal device.

In FIG. 5, 5 and 6 are input terminals connected to the AC power supply 1, 7 is a power supply circuit connected to the input terminals 5 and 6, 8 is a control unit connected to the power supply circuit 7, and 9 is a power supply. The output switching units 10 and 11 connected to the circuit 7 and the control unit 8 are output terminals that connect the output switching unit 9 and the transmission lines 3a and 3b.

In FIG. 6, the control unit 8 includes a control circuit 12 connected to the power supply circuit 7, buffer circuits 13 and 14 connected to the control circuit 12, and a control circuit 12 on the output side.
And the comparator 15 connected to the
5 is connected to the input side of the resistor 16 (R1).

The output switching section 9 is composed of four transistors 17, 18, 19 and 20. The collectors of the transistors 17 and 19 are connected to the power supply circuit 7, the connection points between the emitters of the transistors 17 and 18 are connected to the transmission line 3a, and the connection points between the emitters of the transistors 19 and 20 are connected to the transmission line 3b. Has been done. The connection point between the bases of the transistors 17 and 18 is connected to the output side of the buffer circuit 13, the connection point between the bases of the transistors 19 and 20 is connected to the output side of the buffer circuit 14, and the collector of the transistor 18 is connected. Is grounded, and the collector of the transistor 20 is connected to the input side of the comparator 15.

Further, the structure of the conventional transmission terminal unit 4 of the transmission line feeding system will be described with reference to FIG. FIG. 7 is a circuit diagram partially showing a block diagram of a conventional transmission terminal of the transmission line feeding system.

In FIG. 7, 21 and 22 are transmission lines 3.
Input / output terminals connected to a and 3b, input / output terminal 2 is 23
1, a diode bridge circuit connected to 22; 24, a transistor connected to the diode bridge circuit 23; 25, a power supply circuit including a regulator, 26, a smoothing capacitor, 27, a control unit, 28, an input / output terminal 22
The diode 29 connected to is a resistor (R2).
The base of the transistor 24 is connected to the control unit 27, and the connection point between the diode 28 and the resistor 29 is connected to the control unit 27.

The transmission power source 2 switches the transmission code to the "+" polarity when the transmission code is "1" and to the "-" polarity when the transmission code is "0". This switching is performed by the control unit 8
To discriminate between the steady current of the transmission terminal 4 and the line short-circuit current. It should be noted that when a short circuit occurs, the code is "0", and the others are "1".

[0010]

In the conventional transmission system as described above, it is difficult to discriminate from the short-circuit current when the load fluctuation of the transmission terminal 4 is large with the "+" polarity. Therefore, if the discrimination value of the short-circuit current including the fluctuation is set to a high position (large current value), it takes time for the transmission power supply 2 to detect the short-circuit current due to the line delay, and the delay becomes large. Further, since the transmission terminal device 4 has the line short-circuited, it is necessary to continue the operation with the charging energy of the internal smoothing capacitor 26 during this period. Therefore, during the next charging, the charging current becomes large, the line current fluctuation becomes large, and the difference between the short-circuit current becomes small, the transmission signal (current) of the transmission terminal device 4 and the load fluctuation of the transmission terminal device 4, the power supply unit. There is a problem in that the charging current to the (smoothing capacitor 26) cannot be reliably discriminated.

The present invention has been made in order to solve the above-mentioned problems, and a transmission line power supply system capable of reliably discriminating a transmission signal from a load fluctuation of a transmission terminal and a charging current to a power supply section. The purpose is to obtain a transmission terminal.

[0012]

A transmission line power supply type transmission terminal according to the present invention is provided with the following means. [1] A current limiting circuit that limits the charging current to the power supply unit. [2] A control unit that controls the current limiting circuit based on the sign of the transmission signal on the transmission line.

[0013]

In the present invention, the current limiting circuit
The charging current to the power supply is limited. Further, the control unit controls the current limiting circuit based on the sign of the transmission signal on the transmission line.

[0014]

EXAMPLES Example 1. A configuration of a transmission system using the first embodiment of the present invention will be described with reference to FIG. Figure 1
FIG. 3 is a block diagram showing a transmission system using the first embodiment of the present invention, in which the AC power supply 1, the transmission power supply 2 and the transmission lines 3a, 3b are the same as those in the conventional system described above. In the drawings, the same reference numerals indicate the same or corresponding parts.

In FIG. 1, reference numeral 4A denotes a plurality of transmission terminals connected to the transmission power source 2 through the transmission lines 3a and 3b.

The configuration of the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a circuit diagram showing a partial block diagram of the first embodiment of the present invention.
9 is the same as that of the above-mentioned conventional device.

In FIG. 2, reference numeral 30 denotes a current limiting circuit, which is a resistor 31 (R3) inserted between the diode bridge circuit 23 and the power supply circuit 25 and a transistor 32 having a collector-emitter connected in parallel to the resistor 31. It consists of The base of the transistor 32 is connected to the control unit 27.

Next, the operation of the above-described first embodiment will be described with reference to FIG. FIG. 3 is a diagram showing a transmission signal voltage according to the first embodiment of the present invention.

It comprises a transmission power supply 2, transmission lines 3a and 3b, and a transmission terminal 4A, and the transmission terminal 4A includes the transmission lines 3a and 3a.
An object of the present invention is to reliably discriminate between a transmission signal (current) of the transmission terminal device 4A, a load variation of the transmission terminal device 4A, and a charging current of a power supply unit in a transmission system that receives power through b. Another object is to suppress fluctuations in the power supply voltage of the transmission terminal device 4A and stabilize it.

The basic operation is the same as that of the conventional transmission terminal 4. The control unit 27 of the transmission terminal device 4A discriminates the polarity of the line by the potential of the connection point of the diode 28 and the resistor 29, and the transmission power supply 2 changes from the transmission code "1" to "0" by the current limiting circuit 30. Only when the polarity is required to detect the current limit is added a current limit commensurate with its own steady current. That is, when the transmission power source 2 has a "-" polarity that does not require the detection of the transmission code, the current limitation is released and quick charging is performed to suppress the power supply fluctuation of the transmission terminal 4A.

The first embodiment of the present invention, as described above,
Since the current limiting circuit 30 is provided, the transmission lines 3a, 3b
Since the difference between the above steady current and short circuit current can be set small,
The detection delay can be reduced, which in turn results in current signals and load fluctuations.
As a result, it is possible to reliably discriminate the charging current of the power supply unit and suppress fluctuations in the power supply.

[0022]

As described above, the present invention is based on the current limiting circuit for limiting the charging current to the power supply unit and the code of the transmission signal on the transmission line in the transmission terminal which receives power from the transmission line. Since the control unit for controlling the current limiting circuit is provided, the load fluctuation of the transmission signal and the transmission terminal,
It is possible to reliably discriminate the charging current to the power supply unit.

[Brief description of drawings]

FIG. 1 is a block diagram showing a transmission system using a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a first embodiment of the present invention.

FIG. 3 is a diagram showing a transmission signal voltage according to the first embodiment of the present invention.

FIG. 4 is a block diagram showing a transmission system using a transmission terminal of a conventional transmission line power feeding system.

FIG. 5 is a block diagram showing a transmission power supply in a conventional transmission system.

FIG. 6 is a circuit diagram showing a transmission power supply in a conventional transmission system.

FIG. 7 is a circuit diagram showing a conventional transmission terminal of a transmission line power feeding system.

[Explanation of symbols]

 2 transmission power supply 3a, 3b transmission line 4A transmission terminal 24 transistor 25 power supply circuit 26 smoothing capacitor 27 control unit 30 current limiting circuit 31 resistance 32 transistor

Claims (1)

[Claims] 1. In a transmission terminal device that receives power from a transmission line, a current limiting circuit that limits a charging current to a power supply unit, and a control unit that controls the current limiting circuit based on a sign of a transmission signal on the transmission line. A transmission terminal device of a transmission line power feeding system characterized by comprising: