KR100739596B1 - Plasma display device and driving device thereof - Google Patents

Abstract

A plasma display device and a driving method thereof are provided to reduce EMI(Electro Magnetic Interference) by additionally implementing an inductor and a capacitor in a sustain discharge driver. A plasma display device includes a plasma display panel, a controller, and a driver. The plasma display panel includes panel capacitors formed by plural first and second electrodes. A frame is divided into plural sub-fields. The plasma display panel is driven by the controller. The driver alternately supplies first and second voltages to the first and second electrodes during a sustain period. The driver includes a first transistor(Ys'), a first capacitor(C), and an inductor(L). The first transistor connected between a first voltage source and the first electrodes supplies the first voltage to the first electrodes. The first capacitor and the inductor are electrically connected between first and second terminals of the first transistor.

Description

Plasma display and its driving device {PLASMA DISPLAY DEVICE AND DRIVING DEVICE THEREOF}

1 is a conceptual diagram of a plasma display device according to an exemplary embodiment of the present invention.

2 is a driving waveform diagram of a plasma display device according to an exemplary embodiment of the present invention.

3 illustrates a sustain discharge driving circuit of a plasma display device according to an exemplary embodiment of the present invention.

4 is a view showing a switch device according to an embodiment of the present invention.

FIG. 5 is a diagram comparing the frequency characteristics in the case of using the general transistor shown in FIG. 3 and the frequency characteristics in the case of using the transistor Ys' in FIG. 4 in the sustain discharge driving circuit of FIG. 3.

The present invention relates to a plasma display device and a driving device thereof.

The plasma display device is a flat display device that displays characters or images by using plasma generated by gas discharge. In the display panel of the plasma display device, tens to millions or more of discharge cells (hereinafter, referred to as "cells") are arranged in a matrix form according to their size. The plasma display device is classified into a direct current type and an alternating current type according to the shape of a driving voltage waveform to be applied and the structure of a discharge cell.

In the DC plasma display device, since the electrode is exposed to the discharge space as it is, current flows in the discharge space while voltage is applied, and there is a disadvantage in that a resistor for limiting the current must be configured. On the other hand, in the AC plasma display device, since the electrode covers the dielectric layer, the current is limited by the formation of a natural capacitance component, and the electrode is protected from the impact of ions during discharge.

In general, an AC plasma display device is driven by dividing one frame into a plurality of subfields having respective gray scale weights. In this case, the luminance of the discharge cells is determined by the sum of the weights of the subfields emitted by the corresponding discharge cells among the plurality of subfields. Each subfield also includes a reset period, an address period, and a sustain period.

On the other hand, since a plurality of power sources are used to drive the plasma display device, a plurality of switch elements for applying a plurality of power sources are required. Also, in recent years, the magnitude of the unit light and the luminance represented by the plasma display device tends to increase, and the plurality of switch elements included in the plasma display device have high voltage / high frequency characteristics. When the switch element having such a high voltage high frequency characteristic performs a switching operation, an increase in noise causes electromagnetic interference (hereinafter referred to as “EMI”), so that the plasma display device may not operate stably. There is a problem.

The present invention is to solve the problems of the prior art, and to provide a plasma display device and a driving device that can operate stably by reducing the EMI to the technical problem.

In order to achieve the above technical problem, an aspect of the present invention provides an apparatus for driving a plasma display device including a plurality of first electrodes and a plurality of second electrodes. In the driving apparatus of the plasma display device, a first transistor and a first voltage having a first end connected to a first power supply for supplying a first voltage and electrically connected to a second end of the plurality of first electrodes. A first transistor is connected to a second power supply for supplying a lower second voltage, and a second transistor is electrically connected to a second terminal of the plurality of first electrodes. The first inductor having the inductance variable and the first capacitor are electrically connected between the first end and the second end of the first transistor, and the first inductance having a variable inductance between the first end and the second end of the second transistor. The second inductor and the second capacitor are electrically connected.

In this case, the first voltage is a voltage that is alternately applied to the plurality of first electrodes and the second electrode in the sustain period, and by adjusting the inductance of the first inductor, the resonance frequency according to the switching operation of the first transistor. The time constant of the resonance frequency according to the switching operation of the second transistor may be adjusted by adjusting the time constant and adjusting the inductance of the second inductor.

According to another aspect of the present invention, there is provided a plasma display panel including a plurality of first electrodes and a plurality of second electrodes, wherein a panel capacitor is formed by the first electrode and a second electrode corresponding to the first electrode, A control unit for dividing one frame into a plurality of subfields to drive the plasma display panel, and a first voltage and a first lower voltage lower than the first voltage alternately to the plurality of first and second electrodes during a sustain period. A plasma display device including a driver for applying two voltages is provided. The driving unit may include a first power supply for supplying the first voltage and a first transistor connected between the plurality of first electrodes and the first power supply and supplying the first voltage to the plurality of first electrodes when turned on. And a first inductor having a variable inductance and a first capacitor are electrically connected between the first end and the second end of the first transistor. In this case, the time constant of the resonance frequency according to the switching operation of the first transistor may be adjusted by adjusting the inductance of the first inductor.

The driving unit may be connected to a second power supply for supplying a second voltage lower than the first voltage, and between the plurality of first electrodes and the second power supply, and when turned on, the second voltage to the plurality of first electrodes. Further comprising a second transistor for supplying a second capacitor between the first terminal and the second terminal of the second transistor and the second inductor of the variable inductance is electrically connected. At this time, by adjusting the inductance of the second inductor, it is possible to adjust the time constant of the resonance frequency according to the switching operation of the second transistor.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element in between. . In addition, when a part is said to "include" a certain component, which means that it may further include other components, except to exclude other components unless otherwise stated.

Hereinafter, a plasma display device and a driving device thereof according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram of a plasma display device according to an exemplary embodiment of the present invention.

As shown in FIG. 1, a plasma display device according to an exemplary embodiment of the present invention includes a plasma display panel 100, a controller 200, an address electrode driver 300, a scan electrode driver 400, and a sustain electrode driver 500. ). The plasma display panel 100 includes a plurality of address electrodes A1-Am (hereinafter referred to as "A electrodes") extending in a column direction, and a plurality of sustain electrodes X1-Xn (hereinafter referred to as "X electrodes") extending in a row direction. Electrodes ") and a plurality of scan electrodes Y1-Yn (hereinafter referred to as" Y electrodes "). The plurality of Y electrodes Y1-Yn and the X electrodes X1-Xn are arranged in pairs with each other. The discharge cell 12 is formed where the adjacent Y electrodes Y1-Yn, the X electrodes X1-Xn and the A electrodes A1-Am cross each other.

The controller 200 receives an image signal from the outside and outputs an address electrode driving control signal, a sustain electrode driving control signal, and a scan electrode driving control signal. The controller 200 divides and drives one frame into a plurality of subfields having respective weights.

The address electrode driver 300 receives an address electrode driving control signal from the controller 200 and applies a signal for selecting a discharge cell to be displayed to each of the A electrodes A1-Am. The sustain electrode driver 500 receives the sustain electrode driving control signal from the controller 200 to apply a driving voltage to the X electrodes X1-Xn, and the scan electrode driver 400 controls the scan electrode driving from the controller 200. The signal is received and a driving voltage is applied to the Y electrodes Y1-Yn.

Next, a driving waveform of the plasma display device according to an exemplary embodiment of the present invention will be described. In the following description, only the driving waveforms applied to the Y electrode, the X electrode, and the A electrode forming one cell will be described.

2 is a driving waveform diagram of a plasma display device according to an exemplary embodiment of the present invention.

As shown in Fig. 2, in the rising period of the reset period, the voltage of the Y electrode is changed from the Vs voltage to the Vset voltage while the A electrode and the X electrode are kept at the reference voltage (shown as "0V" in Fig. 2). It is gradually increased. In FIG. 2, the voltage of the Y electrode is shown to increase in the form of a lamp. As described above, while the voltage of the Y electrode is increased, a weak discharge (hereinafter referred to as "reset discharge") occurs between the Y electrode and the X electrode and between the Y electrode and the A electrode, and a negative wall is formed on the Y electrode. An electric charge is formed and positive wall charges are formed on the X electrode and the A electrode.

In the falling period of the reset period, while the voltages of the A electrode and the X electrode are maintained at the reference voltage and the Ve voltage, respectively, the voltage of the Y electrode gradually decreases from the Vs voltage to the Vnf voltage. Then, while the voltage of the Y electrode decreases, a weak discharge occurs between the Y electrode and the X electrode, and between the Y electrode and the A electrode, and the negative wall charges formed on the Y electrode and the (+) The wall charge is erased. In general, the magnitude of the voltage (Vnf-Ve) is set near the discharge start voltage Vfxy between the Y electrode and the X electrode. As a result, the wall voltage between the Y electrode and the X electrode becomes almost 0 V, and it is possible to prevent the cells in which the address discharge has not occurred in the address period from being misdischarged in the sustain period.

In the address period, in order to select a discharge cell to be turned on, while a Ve voltage is applied to the X electrode, a scanning pulse having a VscL voltage is sequentially applied to the plurality of Y electrodes. At this time, the Va voltage is applied to the A electrode passing through the discharge cell to be selected from among the plurality of discharge cells to which the VscL voltage is applied by the Y electrode. Then, an address discharge occurs between the A electrode to which the Va voltage is applied and the Y electrode to which the VscL voltage is applied, and the Y electrode to which the VscL voltage is applied, and the X electrode to which the Ve voltage is applied, thereby generating a positive wall charge on the Y electrode, A negative wall charge is formed on the A electrode and the X electrode, respectively. Here, the VscL voltage may be set at a level equal to or lower than the Vnf voltage. The VscH voltage higher than the VscL voltage is applied to the Y electrode to which the VscL voltage is not applied, and the reference voltage is applied to the A electrode of the discharge cell that is not selected.

In the sustain period, a sustain discharge pulse having alternating Vs voltage and 0V voltage is applied to the Y electrode and the X electrode in the opposite phase to generate a sustain discharge between the Y electrode and the X electrode. Thereafter, the process of applying the sustain discharge pulse of the Vs voltage to the Y electrode and the process of applying the sustain discharge pulse of the Vs voltage to the X electrode are repeated the number of times corresponding to the weight indicated by the corresponding subfield.

On the other hand, in the sustain discharge driving circuit which alternately supplies sustain discharge pulses of the Vs voltage level to the Y electrode and the X electrode in the sustain period, a lot of EMI is generated by the sustain discharge pulses of high voltage / high frequency. Hereinafter, a driving apparatus of a plasma display device capable of reducing EMI will be described in detail with reference to FIGS. 3 to 5.

3 shows a sustain discharge driving circuit of the plasma display device.

Hereinafter, a transistor used as a switch element is shown as an n-channel field effect transistor (FET) having a body diode (not shown), where the cathode of the body diode is at the drain of the transistor and the anode of the body diode is Respectively connected to the source of the transistor. Such transistors may be replaced by other switch elements having the same or similar function, and each transistor may be formed of a plurality of transistors connected in parallel. In addition, the capacitive component formed by the Y electrode and the X electrode corresponding to the Y electrode is shown by the panel capacitor Cp, and the power source is shown by the voltage supplied by the power source.

In Fig. 3, only the sustain discharge driving circuits respectively connected to the X electrode and the Y electrode are shown, and this sustain discharge driving circuit alternately applies the sustain discharge pulses of the Vs voltage level to the X electrode and the Y electrode alternately in the sustain period. In addition, parts unnecessary for describing the embodiments of the present invention are omitted or briefly shown. In addition, since the structure and operation of the sustain discharge drive circuit 510 electrically connected to the X electrode and the sustain discharge drive circuit 410 electrically connected to the Y electrode are similar in structure and operation, for the sake of brevity, Only the discharge driving circuit 410 will be described, and a detailed description of the sustain discharge driving circuit 510 connected to the X electrode will be omitted.

The sustain discharge driving circuit 410 connected to the Y electrode recovers and reuses the power of the power supply Vs supplying the Vs voltage, the power supply 0V supplying the 0V voltage, the transistors Ys, Yg, and the panel capacitor Cp. The power recovery circuit 411 is included. Although not shown in detail, the power recovery circuit 411 includes an inductor and a capacitor for reusing the voltage of the panel capacitor by LC resonance, where the capacitor is charged with a voltage having a voltage level between the Vs voltage and the 0V voltage. .

The drain of the transistor Ys is connected to the power supply Vs, the source of the transistor Ys is electrically connected to the Y electrode, and the Vs voltage is applied to the Y electrode when the transistor Ys is turned on. The drain of the transistor Yg is electrically connected to the Y electrode, the source of the transistor Yg is connected to the power source GND, and a 0V voltage is applied to the Y electrode when the transistor Yg is turned on.

On the other hand, parasitic capacitance exists between the source and the drain of the transistors Ys and Yg. In addition, as shown in FIG. 3, parasitic inductance is present in the current path ① of the power supply Vs, the transistor Ys, and the panel capacitor Cp generated when the transistor Ys is turned on. Although not shown separately, parasitic inductances are also present in the current paths of the panel capacitor Cp, the transistor Yg, and the power supply 0V generated by turning on the transistor Yg. By such parasitic capacitance and parasitic inductance, when the transistor Ys or the transistor Yg is turned on, a resonance frequency (hereinafter referred to as "parasitic resonance frequency") is generated.

When the parasitic resonant frequency is included in the measurable frequency range of the plasma display device, since the peak of the power loss according to the parasitic resonant frequency is included in the measurable frequency range, the power loss in the circuit is increased and the radiation dose due to EMI is also increased. Will increase. In this case, the measurable frequency range of the plasma display device may be determined by an experimental method, for example, a frequency band in the range of 30 MHz to 1 GHz. Since a specific method for determining the measurable frequency range of the plasma display device can be easily understood by those skilled in the art, a detailed description thereof will be omitted.

In addition, the EMI radiation amount is maximum when a sustain discharge pulse is applied to the panel capacitor. In particular, when realizing a high gradation image, since the number of switching operations of the switch element included in the sustain discharge driving circuit is greatly increased, the EMI radiation amount is also greatly increased.

4 is an enlarged view of the switch element Ys' according to the embodiment of the present invention.

In the sustain discharge driving circuit, a transistor used as a switch is a field effect transistor (FET) including a source (S), a drain (D), and a gate (G), and is illustrated by a dotted line in FIG. 4. As shown, parasitic capacitance C1 exists between drain D and source S. FIG. As mentioned in FIG. 3, parasitic inductance (not shown) exists in the current path generated when the transistor is turned on. When the parasitic resonance frequency generated by the parasitic capacitance and the parasitic inductance is included in the measurable frequency range of the plasma display device, the maximum amount of power loss is included in the predetermined frequency range, thereby increasing the EMI radiation amount.

Therefore, as shown in FIG. 4, the configuration of the switch element included in the sustain discharge driving circuit can be modified to reduce the EMI radiation amount.

The transistor Ys' according to the embodiment of the present invention, as shown in FIG. 4, includes a source S, a drain D, and a gate G, and additionally, the source S and the drain D. Inductor L and capacitor C are connected in parallel. At this time, the additional capacitor C and the inductor L are connected in series with each other. That is, the first end of the inductor L may be connected to the drain D or the source S of the transistor Ys', and the second end of the inductor L is connected to the first end of the capacitor C. . The second end of the capacitor C is connected to the other end of the drain D or the source S of the transistor Ys' that is not connected to the first end of the inductor L.

Meanwhile, in the sustain discharge driving circuit according to the exemplary embodiment of the present invention, each switch element Ys and Yg connected between the power supply Vs and the panel capacitor Cp or between the power supply 0V and the panel capacitor Cp in FIG. 3. , Xs, Xg) is the same as the configuration of the driving circuit except that the same as the switch element shown in Fig. 4, the description thereof will be omitted.

FIG. 5 is a graph comparing the frequency characteristics when the general transistors Ys, Yg, Xs, and Xg are used in the sustain discharge driving circuit as shown in FIG. 3 with the frequency characteristics when the transistor Ys' according to FIG. 4 is used. to be. In FIG. 5, a change in loss dB according to a frequency range when a general transistor is used is represented by T1, and a change in loss dB according to a frequency range when a transistor Ys ′ according to an embodiment of the present invention is used. T2. In addition, the measurable frequency range of the plasma display device is denoted by f1-f2, and the points of maximum loss dB within a predetermined frequency range are denoted by P1 and P2, respectively.

As shown in FIG. 3, the general transistors Ys, Yg, Xs, and Xg have parasitic capacitances between the drain and the source, and in the current path flowing to apply a voltage to the panel capacitor during the switching operation. Parasitic inductance occurs. Accordingly, parasitic resonance frequencies are generated during the switching operation of the transistors Ys, Yg, Xs, and Xg.

Accordingly, looking at the loss dB according to the frequency characteristics due to the switching operation of a general transistor, as shown by a dotted line in FIG. 5, when the parasitic resonance frequency is included in the measurable frequency range, that is, the predetermined frequency range f1-f2. Since the maximum power loss point P1 exists in the predetermined frequency range, the EMI radiation amount of the sustain discharge driving circuit becomes large. That is, when the parasitic resonant frequency is included in the predetermined frequency range f1-f2, the maximum power loss dB in the predetermined frequency range f1-f2 becomes P1.

On the other hand, as shown in Figure 4, when the capacitor (C) and the inductor (L) in parallel between the drain (D) and the source (S) of the transistor, in addition to the parasitic capacitance and parasitic inductance, added capacitance and inductance Since the time constant can be adjusted by, the resonance frequency may not be included in the frequency measurement range of the plasma display device.

Since the resonance frequency is inversely proportional to the inductance and the capacitance, as shown in Equation 1, the resonance frequency decreases as the inductance and the capacitance increase. That is, referring to the loss dB according to the frequency characteristic by the transistor Ys' according to the embodiment of the present invention, as shown by the solid line in FIG. 5, the inductance of the inductor is adjusted to provide a predetermined range f1 to f2. If the resonance frequency is not included in the range, the maximum power loss dB in the predetermined range f1 to f2 becomes P2 lower than P1.

In this case, the inductor L added to the transistor may be configured as an inductor element having a small inductance such that the resonance frequency is greater than or equal to the f2 frequency in a predetermined range. However, inductor elements having a very small inductance have difficulty in manufacturing. . Therefore, as shown in Fig. 5, the inductor L is composed of an inductor element having a large inductance so that the resonance frequency is less than the f1 frequency. In this case, the inductor L is used as a device having a variable inductance whose inductance value is changed so as to easily adjust the time constant of the resonance frequency.

As described above, according to an embodiment of the present invention, a plurality of switch elements electrically connected between a power supply and an electrode in a sustain discharge driving circuit, and transistors connecting an inductor and a capacitor having a variable inductance between a drain and a source By using it, the circuit is operated stably by preventing EMI from increasing.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

As described above, according to the exemplary embodiment of the present invention, an inductor and a capacitor may be additionally connected to a transistor connected to each power source in a sustain discharge driving circuit, thereby implementing a driving circuit of a plasma display device capable of reducing EMI.

Claims (11)

In the apparatus for driving a plasma display device comprising a plurality of first electrodes and a plurality of second electrodes, A first transistor having a first end connected to a first power supply for supplying a first voltage, and having a second end electrically connected to the plurality of first electrodes; A second transistor having a first end connected to a second power supply for supplying a second voltage lower than the first voltage, and having a second end electrically connected to the plurality of first electrodes; A first inductor having a variable inductance and a first capacitor electrically connected between the first and second ends of the first transistor, and a second inductor having a variable inductance between the first and second ends of the second transistor. And a driving device of the plasma display device to which the second capacitor is electrically connected. The method of claim 1, The first capacitor and the first inductor are connected in series with each other, And the second capacitor and the second inductor are connected in series with each other. The method of claim 1, And the first voltage is a voltage that is alternately applied to the plurality of first and second electrodes in a sustain period. The method according to any one of claims 1 to 3, By adjusting the inductance of the first inductor, the time constant of the resonance frequency according to the switching operation of the first transistor, And a time constant of a resonance frequency according to a switching operation of the second transistor by adjusting an inductance of the second inductor. The method of claim 1, A third capacitor is further connected between the first and second ends of the first transistor, And a fourth capacitor is further connected between the first end and the second end of the second transistor. A plasma display panel including a plurality of first electrodes and a plurality of second electrodes, the panel capacitor being formed by the first electrode and a second electrode corresponding to the first electrode, A controller for dividing one frame into a plurality of subfields to drive the plasma display panel; In the sustain period, the driving unit for applying a first voltage and a second voltage lower than the first voltage alternately to the plurality of first electrodes and the second electrode, The driving unit may include a first power supply for supplying the first voltage and a first transistor connected between the plurality of first electrodes and the first power supply and supplying the first voltage to the plurality of first electrodes when turned on. Including; And a first capacitor and a first inductor having a variable inductance are electrically connected between the first and second ends of the first transistor. The method of claim 6, And the first capacitor and the first inductor are connected in series. The method according to claim 6 or 7, And a time constant of a resonance frequency according to a switching operation of the first transistor by adjusting an inductance of the first inductor. The method of claim 6, The driving unit is connected between a second power supply for supplying a second voltage lower than the first voltage and the plurality of first electrodes and the second power supply, and when turned on, supplies the second voltage to the plurality of first electrodes. Further comprising a second transistor, And a second capacitor and a second inductor having a variable inductance are electrically connected between the first and second ends of the second transistor. The method of claim 9, And the second capacitor and the second inductor are connected in series. The method of claim 9 or 10, And a time constant of a resonance frequency according to a switching operation of the second transistor by adjusting an inductance of the second inductor.

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