JPH05199145A - Transmission power supply equipment - Google Patents

Abstract

PURPOSE:To attain long distance high speed transmission by selecting a threshold level used to detect a signal on a transmission line in response to a steady- state current flowing to the transmission line and inverting the polarity of a DC power supply when the signal is detected. CONSTITUTION:An output changeover section 9 inverts the polarity of a DC power supply supplied to a transmission line in response to a signal on the transmission line. Moreover, a control section 8 selects a threshold level used to detect the signal in response to a steady-state current flowing to the transmission line. When the signal is detected, the output changeover section 9 is controlled to invert the polarity of the power supply. Thus, the steady-state current is divided into two-values or over, and a detection level of the transmission current (short-circuit current) in matching with the divided current level is selected and the result is used for a reference level of a comparator to detect the short-circuit current. That is, since the short-circuit current is discriminated by a current equivalent to (steady-state current +alpha) used at present, the short- circuit current is detected with a minimum delay time in the transmission line even when the steady-state current is small or large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission power supply device for a transmission system.

[0002]

2. Description of the Related Art First, a configuration of a transmission system using a conventional transmission power supply device will be described with reference to FIG. Figure 5
FIG. 6 is a block diagram showing a transmission system using a conventional transmission power supply device.

In FIG. 5, 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, 4a, 4b and 4c are connected to the transmission power supply 2 through transmission lines 3a and 3b. The transmission terminal is

The configuration of a conventional transmission power supply device is shown in FIGS. 6 and 7.
Will be described with reference to. FIG. 6 is a block diagram showing a conventional transmission power supply device, and FIG. 7 is a circuit diagram showing a conventional transmission power supply device.

In FIG. 6, 5 and 6 are input terminals connected to the AC power supply 1, 7 is a power supply section, 8 is a control section, 9 is an output switching section, and 10 and 11 are connected to the transmission lines 3a and 3b. It is an output terminal.

In FIG. 7, the control unit 8 includes a control circuit 12
And buffer circuits 13 and 14 connected to the control circuit 12, and a transmission current detection circuit 15. The output switching unit 9 also includes transistors 16, 17, 18 and 19. The transmission current detection circuit 15 in the control unit 8 is
Comparator 20, reference voltage 21, current detection resistor 2
2 and.

Further, the structure of the transmission terminal will be described with reference to FIG. FIG. 8 is a block diagram showing a transmission terminal.

In the transmission terminal 4a shown in FIG.
Is an input terminal connected to the transmission lines 3a and 3b, 25 is a diode bridge circuit connected to the input terminals 23 and 24,
26 is a transistor connected to the diode bridge circuit 25, 27 is a power supply circuit, 28 is a control unit, 29 is a diode, and 30 is a resistor. The other transmission terminals 4b, 4
c has the same configuration.

Next, the operation of the above-mentioned conventional transmission power supply device will be described with reference to FIG. FIG. 9 is a timing chart showing the operation of the conventional transmission power supply device. In FIG. 9, (a) is an output voltage waveform of the transmission power supply device, (b) is
Shows the signal current waveforms of the transmission lines, respectively.

Further, t ₁ shown in FIG. 9A indicates a short circuit current detection switching time, V ₁ indicates an ideal voltage waveform (dotted line), and V 2 indicates an actual voltage waveform (solid line). Further, is shown in FIG. 3B is a short circuit current of the transistor 26 in the transmission terminal 4a, and S _F is a fixed threshold value determined by the reference voltage 21 of the transmission current detection circuit 15.

When transmission is started by the transmission terminal, FIG.
The current on the transmission lines 3a and 3b increases along the curve shown in (b). On the other hand, the transmission current detection circuit 15 in the transmission power supply device 2 outputs “L” (low level) to the control circuit 12 when the current reaches the threshold value S _F. Then, the control circuit 12 operates the transistors 16 to 19 in the output switching unit 9 through the buffer circuits 13 and 14 to invert the polarity of the DC power supply as shown in FIG. 9A. Then, since the polarity is reversed, the transmission from the transmission terminal is stopped, and the steady current is restored as shown in FIG.

However, when the number of transmission terminals connected to the transmission lines 3a and 3b is small, the consumption currents of those terminals are small, and the steady current becomes small and does not reach far. Further, the short-circuit current detection switching time t ₁ becomes long, and switching of the polarity is delayed.

That is, the threshold value S _F (= reference voltage 21) of the transmission current detection circuit 15 is set to a value obtained by adding a predetermined value α to the rated value of the steady current to discriminate the transmission current. Therefore, when the short-circuit current from the steady current corresponding to the rated current reaches the threshold value _SF , the short-circuit current detection switching time t ₁ is short, but the steady current is considerably smaller than the rated current when the number of transmission terminals is small. In the case of current, it takes time to reach the threshold value S _F , delay becomes large, and the transmission speed and the transmission distance are restricted.

[0014]

In the conventional transmission power supply device as described above, the threshold value S of the transmission current detection circuit 15 is set.
_{Since F} is fixed, the short-circuit current may be delayed by the transmission lines 3a and 3b in some cases, resulting in a long detection time,
There is a problem that it becomes a constraint for long distance and high speed.

The present invention has been made in order to solve the above-mentioned problems, and an object thereof is to obtain a transmission power supply device capable of long-distance, high-speed transmission.

[0016]

A transmission power supply device according to claim 1 of the present invention comprises the following means. [1] An output switching unit that switches the polarity of a DC power supply supplied to the transmission line according to a signal on the transmission line. [2] The threshold value for detecting a signal on the transmission line is switched according to the magnitude of a steady current flowing through the transmission line, and the polarity is switched when the signal on the transmission line is detected. Control unit that controls the.

The transmission power supply device according to claim 2 of the present invention comprises the following means. [1] An output switching unit that switches the polarity of a DC power supply supplied to the transmission line according to a signal on the transmission line. [2] A threshold value for detecting a signal on the transmission line is set by adding a predetermined value to the magnitude of the steady current flowing through the transmission line, and the polarity is switched when the signal on the transmission line is detected. A control unit for controlling the output switching unit.

[0018]

In the transmission power supply device according to the first aspect of the present invention, the polarity of the DC power supply supplied to the transmission line is switched by the output switching unit according to the signal on the transmission line.
Further, the control unit switches a threshold value for detecting a signal on the transmission line according to the magnitude of a steady current flowing through the transmission line, and switches the polarity when the signal on the transmission line is detected. The output switching unit is controlled.

In the transmission power supply device according to the second aspect of the present invention, the polarity of the DC power supply supplied to the transmission line is switched by the output switching unit according to the signal on the transmission line. Further, the control unit adds a predetermined value to the magnitude of the steady-state current flowing in the transmission line to set a threshold value for detecting a signal on the transmission line, and when a signal on the transmission line is detected, The output switching unit is controlled so as to switch the polarity.

[0020]

EXAMPLES Example 1. FIG. 1 shows the configuration of the first embodiment of the present invention.
2 and FIG. 2. 1 is a circuit diagram showing a partial block diagram of Embodiment 1 of the present invention, and a power supply unit 7 and an output switching unit 9 are the same as those of the conventional device described above. In the drawings, the same reference numerals indicate the same or corresponding parts.

In FIG. 1, the control unit 8 includes a control circuit 12 connected to the power supply unit 7, buffer circuits 13 and 14 connected to the control circuit 12, and an input side connected to the output switching unit 9 and an output side. It is composed of a transmission current detection circuit 15A connected to the control circuit 12.

FIG. 2 is a circuit diagram showing a transmission current detection circuit 15A according to the first embodiment of the present invention. In FIG. 2, 31 is a buffer circuit connected to the connection point between the output switching unit 9 and the current detection resistor 22, 32 and 33 are resistors connected to the buffer circuit 31 and forming an integrating circuit for smoothing the transmission current. Capacitors, 34 and 35 are resistors for dividing the reference power source, 36 is a comparator, 37 is an inverter, 3
8, 39, 40 are resistors for dividing the reference power source, 41, 42
Is an analog switch.

Next, the operation of the above-described first embodiment will be described with reference to FIG. FIG. 3 is a diagram showing the operation of the transmission current detection circuit 15A according to the first embodiment of the present invention. In FIG. 3, (a) shows the case where the steady current is small, and (b) shows the case where the steady current is large.

As shown in FIG. 3A, when the steady current is small, the comparator 36 outputs "H" (high level), so that the analog switch 42 is turned on and the analog switch 41 is turned off. Therefore, the comparator 2
A low voltage applied to the resistor 40 is applied to the non-inverting input terminal of 0. That is, the transmission current detection circuit 15A has the configuration shown in FIG.
As shown in (a), a low threshold value S _L will be set.

On the other hand, as shown in FIG. 3B, when the steady current is large, the comparator 36 outputs "L", so that the analog switch 41 is turned on and the analog switch 42 is turned off. Therefore, the high voltage applied to the resistors 39 and 40 is applied to the non-inverting input terminal of the comparator 20. That is, the transmission current detection circuit 15A has the configuration shown in FIG.
As shown in (b), a high threshold value S _H is set.

The first embodiment of the present invention, as described above,
In the detection of the transmission current (short-circuit current), at least the steady-state current is divided into two or more values, and the short-circuit current detection level is switched to match each value, and the short-circuit current is detected by using this as the reference level of the comparator 20. That is, since the short-circuit current is discriminated according to the steady-state current + α currently in use, the delay time of the short-circuit current in the transmission line can be detected at the minimum regardless of whether the steady-state current is small or large, which leads to high-speed and long-running. This has the effect of enabling distance transmission.

Example 2. The configuration of the second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a circuit diagram showing a transmission current detection circuit 15B according to the second embodiment of the present invention. The comparator 20, the current detection resistor 22, the buffer circuit 31, and the capacitor 33 are the transmission current detection circuit 15A according to the first embodiment.
Similar to that of. The power supply unit and the output switching unit of the second embodiment are the same as those of the first embodiment.

In FIG. 4, 43 is a resistor connected to an integrating circuit composed of a resistor 32 and a capacitor 33, 44 is an operational amplifier having a resistor 43 connected to its inverting input terminal, and 45.
Is a resistor connected between the output terminal and the inverting input terminal of the operational amplifier 44, and 46 is a resistor connected between the reference voltage 47 and the inverting input terminal of the operational amplifier 44. The adder circuit 48 includes resistors 43 to 46.

In the second embodiment of the present invention, an adder circuit 48 for adding an α-equivalent current equivalent to a steady current + α is provided in the transmission current detection circuit 15B, and the output of this addition circuit 48 is used as the reference level of the comparator 20. As a result, the short-circuit current is discriminated by the equivalent of the steady current currently used + α. Therefore, when the steady current is small or large, the short-circuit current is detected by the threshold value with a certain margin value added. Delay time to the minimum, which in turn is fast,
This has the effect of enabling long-distance transmission.

[0030]

As described above, the transmission power supply device according to claim 1 of the present invention includes an output switching unit for switching the polarity of the DC power supply supplied to the transmission line in accordance with a signal on the transmission line, and the transmission line. A control unit for controlling the output switching unit so as to switch the polarity when detecting a signal on the transmission line by switching a threshold value for detecting a signal on the transmission line according to the magnitude of a steady current flowing through Since it is provided, the effect of enabling long-distance and high-speed transmission is achieved.

As described above, the transmission power supply device according to claim 2 of the present invention flows to the transmission line and an output switching unit that switches the polarity of the DC power supply supplied to the transmission line in accordance with the signal on the transmission line. A predetermined value is added to the magnitude of the steady current to set a threshold value for detecting a signal on the transmission line, and the output switching unit is controlled to switch the polarity when the signal on the transmission line is detected. Since the control unit is provided, it is possible to achieve long distance and high speed transmission.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram showing a transmission current detection circuit according to the first embodiment of the present invention.

FIG. 3 is a diagram showing an operation of the transmission current detection circuit according to the first embodiment of the present invention.

FIG. 4 is a circuit diagram showing a transmission current detection circuit according to a second embodiment of the present invention.

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

FIG. 6 is a block diagram showing a conventional transmission power supply device.

FIG. 7 is a circuit diagram showing a conventional transmission power supply device.

FIG. 8 is a block diagram showing a transmission terminal connected to a conventional transmission power supply device.

FIG. 9 is a timing chart showing an operation of a conventional transmission power supply device.

[Explanation of symbols]

 7 Power Supply Section 8 Control Section 9 Output Switching Section 15A, 15B Transmission Current Detection Circuit 20 Comparator 22 Current Detection Resistor 36 Comparator 41, 42 Analog Switch 48 Adder Circuit

Claims (2)

[Claims] 1. An output switching unit that switches the polarity of a DC power source supplied to the transmission line according to a signal on the transmission line, and a signal on the transmission line is detected according to the magnitude of a steady current flowing in the transmission line. The transmission power supply device is provided with a control unit that controls the output switching unit so as to switch the polarity when a signal on the transmission line is detected by switching the threshold value for switching. 2. An output switching unit that switches the polarity of a DC power source supplied to the transmission line according to a signal on the transmission line, and a predetermined value is added to the magnitude of a steady-state current flowing through the transmission line, and the output current is on the transmission line. A transmission power supply device comprising: a control unit that sets a threshold value for detecting a signal and controls the output switching unit to switch the polarity when a signal on the transmission line is detected.