JPH10171404A - Power circuit - Google Patents

Abstract

(57) Abstract: The present invention relates to a system device for connecting a power supply device 1 and a plasma display device 3 via a relay cable 2, and when a relay cable becomes long, a high-voltage power supply interferes with a low-voltage power supply. What prevents. SOLUTION: The earth of a high voltage system power source and the earth of a low voltage system power source of a power supply device 1 are separated from each other, and a resistor 7 is provided between the high voltage system earth and the low voltage system earth. , So that the high-voltage power supply does not interfere with the low-voltage power supply even if the resistance value of the electric wire increases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver in which power supply means for supplying electric power such as a drive voltage and image display means for displaying an image are separated and both are connected by a relay cable. The present invention relates to a power supply circuit used for a video display device such as a display.

[0002]

2. Description of the Related Art Recently, a color CR has been used as a video display device.
T is widely used, but instead of this, for example, a liquid crystal panel or a plasma display for color display having a memory function is demanded as a device that can be significantly thinned. As the thickness of the display unit has been reduced, a two-body image display device of this type has been developed in which an image display means for displaying an image and a power supply means for supplying a drive voltage to the image display means are separated. As an example, a DC type plasma display will be described below.

As shown in FIG. 4, a DC type plasma display generally has two types of display: a scanning electrode group 101 composed of cathodes K1, K2,... And a display electrode group 102 composed of anodes A1, A2, A3,. Having a matrix electrode group,
Each intersection constitutes an individual display discharge cell. A discharge gas is sealed between the display electrode group 102 and the scan electrode group 101, and discharge / emission occurs at a discharge cell at the intersection of the display electrode and the scan electrode to which a voltage is applied in accordance with display information. Recognized as information. In the case of performing color display, a phosphor is provided in each discharge cell, and a discharge gas such as helium-xenon, which emits ultraviolet light at the time of discharge, is sealed. A method of driving the thus configured plasma display by a pulse memory method will be described with reference to FIG.

[0004] As shown in FIG.
The write pulse VA is applied to the electrodes 1, A2, A3,.
Is applied according to the display information, and the scanning electrode group 101
Are successively applied with negative voltage scanning pulses VK. In such an applied voltage waveform, for example, a method of writing display information into the discharge cell 103 corresponding to the intersection of the anode A2 and the cathode K2 and maintaining the discharge will be described.

As shown in FIG. 5, when the write pulse VA is applied to the anode A2 while the scan pulse VK1 is applied to the cathode K2, a pulse discharge is generated in the discharge cell 103 at the intersection of the anode A2 and the cathode K2. And lower the firing voltage of the cell. The discharge cell 103 once written in this way discharges and emits light every time the sustain pulse VK2 is applied until the erase pulse VE is applied to the cathode. Since the voltage of the erase pulse VE is set so that the voltage between the cathode and the display anode is equal to or lower than the discharge start voltage, the subsequent discharge stops. When no write pulse is applied, or after the erase pulse is applied and the discharge is once stopped, the discharge start voltage of the display discharge cell 103 is kept at a high state, so that the discharge light emission by the sustain pulse does not occur. As described above, in the memory driving method represented by the pulse memory method, high luminance can be obtained because pulse emission repeated during a period from a writing pulse to an erasing pulse can be used for display.

[0006]

In a system using the above-described plasma display device, if an example of each applied pulse voltage is given, the display electrode pulse voltage is about 65.
V, scanning cathode pulse voltage is about -150V to -250V
Voltage is required. Therefore, the power supply voltage is 65V,
Requires relatively high voltages such as -150V, -250V.

In a conventional plasma display device, an integrated device including a power supply as shown in FIG. 3A or a power supply device 1 having a built-in power supply circuit as shown in FIG. There is a method of forming a two-body type with the plasma display device 3. Here, in the integrated type shown in FIG. 3A, even if a high voltage is used, the same cabinet is used and no particular problem occurs. However, in order to take advantage of the thin features of the plasma display, it is better to separate the power supply device to take advantage of the features. In this case, it is necessary to connect the power supply device and the plasma display device with the relay cable 2 and supply a high voltage and a low voltage through the relay cable 2. At this time, when the relay cable 2 is long (from 5 m to 1
0m), because the amount of current of the high voltage system such as -250V and -150V is large (around 1A), the ground of the low voltage system such as 12V and 5V is affected, and the low voltage system power supply is disturbed by the high voltage system. The image is disturbed.

[0008]

In order to solve the above-mentioned problems, a power supply circuit according to the present invention is designed so that the ground of a power supply corresponding to a plasma display device and the ground of a low-voltage power supply are not disturbed by a high-voltage power supply. The power supply unit separates the high-voltage system ground and the low-voltage system ground so that the plasma display unit has a common ground so that a long relay cable does not have a common ground impedance. is there.

As a second means, when the power supply side ground cannot be separated for some reason or when the low voltage ground is disturbed by the high voltage system on the plasma display device side, the current change of the high voltage system is caused. Is added to the low-pressure system in opposite phase to cancel out.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a high-quality image by preventing a high-voltage power supply of a power supply unit from interfering with a low-voltage power supply.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A power supply circuit according to the present invention comprises an image display device for displaying an image, a power supply device for supplying power to the image display device, and a relay cable for connecting the image display device and the power supply device. Wherein the power supply device side ground is separately supplied to a high voltage system and a low voltage system, and the image display device side is connected to the high voltage system ground and the low voltage system ground. Things. According to this configuration, even when the power is supplied by extending the relay cable connecting the power supply unit and the image display device, it is possible to prevent the image from being disturbed.

Further, the power supply device of the present invention includes an image display device for displaying an image, a power supply device for supplying power to the image display device, and a relay cable for connecting the image display device and the power supply device. The power supply side ground is separately supplied to a high voltage system and a low voltage system, and the high voltage system ground and the low voltage system ground of the power supply side are connected by a resistor,
The image display device is connected to the high-voltage side ground and the low-voltage side ground. Similarly, according to this configuration, even when the power is supplied by lengthening the relay cable connecting the power supply unit and the image display device, it is possible to prevent the image from being disturbed.

Further, the power supply device of the present invention comprises an image display device for displaying an image, a power supply device for supplying power to the image display device, a relay cable for connecting the image display device and the power supply device, The power supply side ground is separately supplied to a high-voltage system and a low-voltage system, and a voltage detector for detecting the voltage fluctuation of the low-voltage system, and the image display is performed by setting the detected voltage fluctuation to an opposite phase. It is characterized in that it is added to the addition of a low-pressure system on the device side. In this configuration, even if the relay cable is long and the resistance due to the ground wire in the cable increases, by canceling it, it is possible to reproduce a good image without disturbing the low-voltage power supply. It is.

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a basic circuit of a power supply circuit according to a first embodiment of the present invention. A description will be given using a plasma display as an example of a two-body image display means.

In FIG. 1, 1 is a power supply device, 2 is a relay cable, 3 is a plasma display device, 4 is a high-voltage power supply (only -250 V is shown), 5 is a high-voltage power supply output line, and 6 is a high-voltage ground. Line, 7 is a resistor for connecting the high voltage system ground and the low voltage system ground, 8 is a low voltage system power supply (only 12 V is shown), 9 is a low voltage system power output line, 10 is a low voltage system ground, and 11 is a high voltage system relay cable. The resistance of the earth wire
2 is the resistance of the ground wire of the low-voltage relay cable, 13 is the high-voltage load in the plasma display device 3, 14 is the ground of the high-voltage load, 15 is the low-voltage load in the plasma display device, and 16 is the low-voltage load. 15 grounds. The power supply circuit configured as described above will be described.

-25 as a high voltage power source in the power supply device 1
The output line 5 and the ground 6 of the 0V power supply 4 are supplied to a high-voltage load 13 in the plasma display device 3 via the relay cable 2. Similarly, the output line 9 and the ground 10 of the 12 V low-voltage power supply 8 are supplied to the low-voltage load 15 in the plasma display device 3 via the relay cable 2.
The high-voltage ground and the low-voltage ground are separated by a resistor 7. The purpose of this resistor 7 is to separate the high-voltage system ground and the low-voltage system ground, but also to make the ground potentials of the high-voltage system and the low-voltage system the same on the power supply side.

Consider the case where the resistor 7 is not provided and the ground line 6 of the high-voltage system power supply and the ground line 10 of the low-voltage system power supply are common without being separated. The power returns to the high-voltage power supply 4 through the ground line 6 and the low-voltage ground line 10.

When the length of the relay cable 2 is long, the DC resistance of the ground wires 6, 10 due to the resistors 11, 12 due to the power supply line cannot be ignored. Then, a voltage fluctuation of the high voltage system occurs in the resistance 12 of the low voltage system power supply ground. This voltage fluctuation causes 12 V of the low-voltage power supply 8 to swing. The low voltage 12V is often used as a power supply for an analog signal processing circuit. In this case, the signal is easily disturbed. Similarly, the high voltage system is also driven by the low voltage system power supply, but is ignored because the original voltage is high.

Next, considering the case where the resistor 7 is provided, the ground current of the high voltage system power supply 4 is reduced by the resistor 7 to the low voltage system ground 1.
The signal is returned to the power supply only through the high-voltage ground line 6 without passing through the zero. In this way, the high-voltage power supply current does not interfere with the low-voltage power supply, and a good image can be obtained. On the plasma display device side, which is the load side, the high voltage side ground 14 and the low voltage side ground 16 are common, and there is no problem. Further, if the resistance 7 is sufficiently larger than the resistance of the power supply line in the relay cable, the problem disappears, and if there is 100Ω in the experiment, there is no problem. Also, since there is almost no potential difference between both ends of the resistor 7 and almost no current flows,
A small-capacity resistor is sufficient.

(Embodiment 2) Next, a second embodiment will be described with reference to the drawings. FIG. 2 shows a basic circuit of a power supply circuit according to a second embodiment of the present invention.

In FIG. 2, only points different from FIG. 1 will be described. Reference numeral 17 denotes a line connected to the ground of the low-voltage power supply 8 in the power supply device 1, reference numeral 18 denotes an adder, and reference numeral 19 denotes the voltage at both ends of the ground line 10 of the low-voltage power supply, and adds the detected voltage to the adder 18 in the opposite phase. Voltage detector. The power supply circuit configured as described above will be described.

The high-voltage system ground and the low-voltage system ground in the power supply device 1 are common, and the low-voltage system power supply fluctuates as the resistance 12 in the relay cable 2 is swung by the high-voltage system power supply. It is about to be supplied to the low pressure system load 15 in the plasma display device. Here, the voltage fluctuation due to the resistor 12 is detected by the voltage detector 19, the phase is reversed and applied to the adder 18 to cancel the fluctuation and applied to the low-voltage load 15.

In this way, even if the relay cable is long and the resistance due to the ground wire in the cable is increased, the resistance is canceled out, so that the low-voltage power supply is not disturbed and a good image can be reproduced.

[0024]

As described above, according to the present invention, in the case of a two-body video display means in which the power supply means and the image display means are separated, when the relay cable is supplied as long as necessary like a plasma display device, However, it is possible to prevent the image from being disturbed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram in a first embodiment of the present invention.

FIG. 2 is a configuration diagram according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a plasma display system.

FIG. 4 is a diagram for explaining electrodes forming a main part of the plasma display device.

FIG. 5 is a diagram illustrating a driving method of a plasma display device of a pulse memory system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 power storage 2 relay cable 3 plasma display device 4 high-voltage power supply 7 resistor 8 low-voltage power supply 12 resistance of low-voltage relay cable 13 high-voltage load 15 low-voltage load 201 scan electrode group 202 display electrode group 203 discharge cell

Claims (3)

[Claims] An image display device for displaying an image; a power supply device for supplying power to the image display device; and a relay cable connecting the image display device and the power supply device. A power supply circuit, wherein a ground is separately supplied to a high-voltage system and a low-voltage system, and the image display device is connected to the high-voltage system ground and the low-voltage system ground. 2. An image display device for displaying an image, a power supply device for supplying power to the image display device, and a relay cable for connecting the image display device and the power supply device. The ground is separately supplied to a high voltage system and a low voltage system, and the high voltage system ground and the low voltage system ground on the power supply device side are connected by a resistor, and the high voltage side ground and the low voltage side are connected on the image display device side. A power supply circuit characterized by connecting to a ground. 3. An image display device for displaying an image, a power supply device for supplying power to the image display device, a relay cable connecting the image display device and the power supply device, and a ground on the power supply device side. A voltage detector that separately supplies a high-voltage system and a low-voltage system, and detects a voltage fluctuation of the low-voltage system,
A power supply circuit, wherein the detected voltage fluctuation is made to have an opposite phase and added to the addition of a low-voltage system on the image display device side.