KR100649191B1 - Plasma display device and driving method thereof - Google Patents

Abstract

A plasma display device and a driving method thereof are provided to perform stable sustain discharge by regulating voltage charged in a power recovery capacitor according to a load factor of a plasma display panel in applying sustain discharge pulse to scan and sustain electrodes during a sustain period. A plasma display device includes a plasma display panel having first and second electrodes, and a driving circuit. The driving circuit applies a first voltage to the first electrode after increasing the voltage of the first electrode through an inductor(L) having a first stage connected to a capacitor(Cp) charged with a predetermined voltage and a second stage coupled to the first electrode, and applies a second voltage to the first electrode after decreasing the voltage of the first electrode through the inductor, during a sustain period. And, the driving circuit charges the capacitor with the voltage during a first period of the period of applying the first voltage to the first electrode, the first period is extended as a screen load factor of the plasma display panel is increased.

Description

Plasma display device and driving method thereof {PLASMA DISPLAY DEVICE AND DRIVING METHOD THEREOF}

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

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

3 is a view schematically showing a sustain discharge driving circuit according to an embodiment of the present invention.

4 is a diagram illustrating a driving timing of the driving circuit illustrated in FIG. 3.

5A to 5C are diagrams illustrating a current path in the driving circuit shown in FIG. 3.

6 is an equivalent circuit diagram of a power recovery circuit according to an embodiment of the present invention.

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

The plasma display device is a display device using a plasma display panel that displays text or an image by using plasma generated by gas discharge. In such plasma display panels, tens to millions or more pixels (discharge cells) are arranged in a matrix form according to their size.

The display panel of the plasma display device is driven by dividing one frame into a plurality of subfields having respective weights, and each subfield is configured for a reset period, an address period, and a sustain period. Is done.

The reset period is a period in which the state of the discharge cells is initialized to stably perform the address discharge, and the address period is a period in which cells to be turned on and cells to be turned off are selected from among the plurality of discharge cells. The sustain period is a period in which sustain discharge is performed for the cells to be turned on to actually display an image.

When performing such an operation, the discharge space between the scan electrode and the sustain electrode, the surface on which the address electrode is formed and the surface on which the scan and sustain electrode are formed, or the like act as a capacitive load (hereinafter referred to as a “panel capacitor”). Thus, capacitance is present in the plasma display panel. Therefore, in order to apply the waveform for sustain discharge in the sustain period, reactive power for generating a predetermined voltage in addition to the power for sustain discharge is required. Therefore, the driving circuit of the plasma display panel generally includes a power recovery circuit for recovering and reusing reactive power. The power recovery circuit is a method of recovering and reusing reactive power by using resonance of a panel capacitor and an inductor, and there are circuits proposed by L.F.Weber (US Pat. Nos. 4,866,349 and 5,081,400) as such power recovery circuits.

On the other hand, in the plasma display device, as the number of sustain discharge pulses increases, that is, as the screen load ratio increases, the current amount increases, and the impedance of parasitic inductive components increases in proportion to the voltage drop.

Therefore, sustain discharge occurs while applying a sustain discharge pulse to the scan electrode and sustain electrode by using the resonance between the panel capacitor and the inductor in the sustain period. The resonance peak voltage is lowered due to the voltage drop, and the discharge is weakly maintained. The time taken for the discharge to increase also increases. Here, the resonance peak voltage refers to the maximum voltage of the panel capacitor by resonance.

Therefore, the sustain discharge becomes unstable in the sustain period due to the voltage drop that increases as the load ratio increases, resulting in discharge spots on the plasma display panel, thereby degrading image quality.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a plasma display device and a driving method thereof capable of improving image quality of a plasma display panel through stable sustain discharge in a sustain period.

According to an aspect of the present invention, a plasma display panel including a first electrode and a second electrode, and in a sustain period, a first end is connected to a capacitor charged with a predetermined voltage and a second end is connected to the first electrode. After the voltage of the first electrode is increased through an inductor connected, a first voltage is applied to the first electrode, and the voltage of the first electrode is decreased through the inductor, and then a second voltage is applied to the first electrode. A plasma display device including a driving circuit to be applied is provided. In this case, the driving circuit charges the voltage in the capacitor during the first period of the period in which the first voltage is applied to the first electrode, and increases the first period as the screen load ratio of the plasma display panel increases.

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According to another aspect of the present invention, a plasma display device includes a plurality of first electrodes, an inductor having a first end connected to the plurality of first electrodes, and a first voltage between a first voltage and a second voltage lower than the first voltage. A capacitor charging a voltage, a first switching element connected between the first power supply for supplying the first voltage and the plurality of first electrodes, a second power supply for supplying the second voltage, and the plurality of firsts A second switching element connected between the electrodes, a third switching element connected between the second end of the inductor and the capacitor, a fourth switching element connected between the second end of the inductor and the capacitor, and a sustain period In the first period of time, the third switching device is turned on, the second switching device is turned on for a second period of time, and the fourth switching device is turned on for a third period of time. And a controller configured to set a turn-on state, set the second switching element to a turn-on state for a fourth period, and set the fourth switching element to a turn-on state during a fifth period of the second period. In this case, the controller sets the fifth period to be longer as the screen load ratio increases.

According to another feature of the present invention, a method of driving a plasma display device including a plurality of first electrodes is provided. The driving method includes, during a sustaining period, increasing a voltage of the plurality of first electrodes through an inductor having a first end connected to a capacitor charging a predetermined voltage and a second end connected to the plurality of first electrodes. Applying a first voltage to the plurality of first electrodes; charging a voltage to the capacitor during a first period of time during which the first voltage is applied to the plurality of first electrodes; Reducing the voltage of the first electrode; and applying a second voltage lower than the first voltage to the first electrode, and lengthening the first period as the screen load ratio of the plasma display device increases. do.

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. Like parts are designated by like reference numerals throughout the specification.

In the present invention, the wall charge refers to a charge formed close to each electrode on the wall of the cell (eg, the dielectric layer). And the wall charge is not actually in contact with the electrode itself, but is described here as “formed”, “accumulated” or “stacked” on the electrode. In addition, the wall voltage refers to the potential difference formed in the wall of the cell by the wall charge.

Now, a plasma display device and a driving method thereof according to an exemplary embodiment of the present invention will be described in detail.

First, a plasma display device according to an exemplary embodiment of the present invention will be described in detail with reference to FIG. 1.

1 is a diagram illustrating 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. It includes.

The plasma display panel 100 includes a plurality of address electrodes A1 to Am extending in the column direction, and a plurality of sustain electrodes X1 to Xn and scan electrodes Y1 to Yn extending in pairs in the row direction. Include. The sustain electrodes X1 to Xn are formed corresponding to the scan electrodes Y1 to Yn, and generally have one end connected to each other in common. The plasma display panel 100 includes a substrate (not shown) on which the sustain and scan electrodes X1 to Xn and Y1 to Yn are arranged, and a substrate (not shown) on which the address electrodes A1 to Am are arranged. The two substrates are disposed to face each other with the discharge space therebetween so that the scan electrodes Y1 to Yn and the address electrodes A1 to Am and the sustain electrodes X1 to Xn and the address electrodes A1 to Am are orthogonal to each other. At this time, the discharge space at the intersection of the address electrodes A1 to Am and the sustain and scan electrodes X1 to Xn and Y1 to Yn forms a discharge cell. The structure of the plasma display panel 100 is an example, and a panel having another structure to which the driving waveform described below may be applied may also be applied to the present invention.

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, and each subfield includes a reset period, an address period, and a sustain period when expressed as a change in time.

In addition, according to an exemplary embodiment of the present disclosure, the control unit 200 transmits a control signal to the scan electrode driver 400 and the sustain electrode driver 500 to increase the resonance peak voltage as the screen load ratio increases. do. Here, the screen load ratio refers to the ratio of the cells that are turned on in the entire screen, and the method for calculating the screen load ratio is a technique that can be easily implemented by those skilled in the art and a detailed description thereof will be omitted.

The address electrode driver 300 receives an address electrode driving control signal from the controller 200 and applies a display data signal for selecting a discharge cell to be displayed to each address electrode.

The scan electrode driver 400 receives a scan electrode driving control signal from the controller 200 and applies a driving voltage to the scan electrode Y.

The sustain electrode driver 500 receives the sustain electrode driving control signal from the controller 200 and applies a driving voltage to the sustain electrode X.

Next, a driving waveform of the plasma display device according to an exemplary embodiment of the present invention will be described in detail with reference to FIG. 2. For convenience of description, the scan electrode (hereinafter referred to as “Y electrode”), the sustain electrode (hereinafter referred to as “X electrode”), and the address electrode (hereinafter referred to as “A electrode”) forming one cell will be described below. Only the driving waveform to be applied will be described.

2 illustrates a driving waveform of a plasma display device according to an exemplary embodiment of the present invention. 2 shows only drive waveforms in the sustain period.

As shown in Fig. 2, in the sustain period, a sustain discharge pulse having a high level voltage (Vs voltage) and a low level voltage (0 V voltage) is alternately applied to the Y electrode and the X electrode in the opposite phase. It is repeatedly applied to the Y electrode and the X electrode as many times as the weight corresponding to the weight indicated by the subfield.

Next, the driving circuit for applying the sustain discharge pulse in the sustain period will be described in detail with reference to FIGS. 3 to 6. 3 to 5C, only the sustain discharge driver circuit of the scan electrode driver 400 is illustrated without the sustain discharge driver circuit of the sustain electrode driver 500. The switching element used below is illustrated as an n-channel transistor, and may be formed of a field effect transistor (FET) having a body diode, and may be formed of another switching element having the same or similar function. The capacitive component formed by the sustain electrode X and the scan electrode Y is shown as a panel capacitor Cp.

3 is a view schematically showing a sustain discharge driving circuit according to an embodiment of the present invention.

As shown in FIG. 3, the sustain discharge driving circuit of the scan electrode driver 400 according to an exemplary embodiment of the present invention includes a power recovery circuit 410 and a sustain discharge voltage supply unit 420.

The power recovery circuit 410 includes switching elements Yr and Yf, an inductor L, diodes D1 and D2 and a capacitor C1. The power recovery capacitor C1 is electrically connected between the drain of the switching element Yr and the source of the switching element Yf, and diodes D1 and D2 are connected in series to the switching elements Yr and Yf, respectively. . One end of the inductor L is electrically connected between a contact between the diodes D1 and D2 and a contact between the switching elements Ys and Yg of the sustain voltage driver 420, and a panel capacitor is connected to the other end of the inductor L. The Y electrodes of Cp) are connected in series. Diode D1 is for setting the rising path of increasing the voltage of panel capacitor Cp when switching element Yr has a body diode and diode D2 is Y when switching element Yf has a body diode. It is for setting a falling path for lowering the voltage of the electrode. In this case, if the switching Yr and Yf do not have a body diode, the diodes D1 and D2 may be removed. The connected power recovery circuit 410 is connected to the voltage of the Y electrode Vs It charges to voltage or discharges to ground voltage.

In the power recovery circuit 310, the order of connection between the inductor L, the diode D1 and the switching element Yr may be changed, and likewise between the inductor L, the diode D2 and the switching element Yf. The order of connections can also be changed.

The sustain discharge voltage supply unit 420 is connected between the power recovery circuit 410 and the panel capacitor Cp, and includes two switching elements Ys and Yg. The switching element Ys is connected between the power supply supplying the sustain discharge voltage Vs and the Y electrode of the panel capacitor Cp, and the switching element Yg is the power supply supplying the ground voltage 0V and the panel capacitor Cp. Is connected between the Y electrodes. This switching element (Ys, Yg) is Vs at the Y electrode. Supply voltage and ground voltage respectively.

Next, the time-series operation change of the sustain discharge driving circuit according to the embodiment of the present invention will be described in detail with reference to FIGS. The phenomenon referred to as LC resonance below is not a continuous oscillation but a change in voltage and current caused by a combination of an inductor L and a panel capacitor Cp occurring at the turn-on of the switching elements Yr and Yf.

4 is a diagram illustrating a driving timing of the driving circuit illustrated in FIG. 3, and FIGS. 5A to 5C are diagrams illustrating a current path in the driving circuit illustrated in FIG. 3. 6 is an equivalent circuit diagram of a power recovery circuit according to an embodiment of the present invention.

First, before the period T1, the switching element Yg is turned on so that the voltage across the panel capacitor Cp is maintained at 0 V, and the capacitor C1 has a voltage equal to 1/2 of the externally applied voltage Vs ( Assume that Vs / 2) is precharged.

In the period T1, the switching element Yr is turned on and the switching element Yg is turned off. Then, as illustrated in FIG. 5A, a current path is formed by the Y electrodes of the ground terminal 0, the capacitor C1, the switching element Yr, the diode D1, the inductor L, and the panel capacitor Cp ( ①). This path (1) forms an LC resonant circuit so that the voltage at the Y electrode of the panel capacitor Cp is Vs. Increases to near voltage.

Next, in the period T2, the switching element Yf is turned on and the switching element Ys is turned off. Then, a path to the Y electrode of the power supply Vs, the switching element Ys, and the panel capacitor Cp is formed as shown in Fig. 5A (2). By this path ②, the Y electrode of the panel capacitor Cp is maintained at the Vs voltage.

In the period T3, the switching element Yf is turned on while the switching element Ys is turned on. Then, as shown in Fig. 5B, a current path to the switching element Ys, the inductor L, the diode D2, the switching element Yf, the capacitor C1, and the ground terminal 0 is formed (3). The capacitor C1 is charged with a predetermined voltage by this path ③. In this case, according to the exemplary embodiment of the present invention, the voltage T1 charged in the capacitor C1 is adjusted by adjusting the period T3 according to the load ratio of the plasma display panel 100. That is, a stable sustain discharge can be achieved by adjusting the voltage charged in the capacitor C1 according to the load ratio of the plasma display panel 100.

Specifically, as the load ratio of the plasma display panel 100 increases, the resonance peak voltage is lowered. Therefore, when the load ratio of the plasma display panel 100 is large, the period T3 is increased so that the voltage charged in the capacitor C1 is increased. Increase the size. As such, when the voltage charged in the capacitor C1 increases, the resonance peak voltage may be increased, thereby stably causing sustain discharge during the period T1 operation.

Here, referring to the relationship between the voltage charged in the capacitor C1 and the voltage of the Y electrode of the panel capacitor Cp, the current flowing through the inductor L at the beginning of the period T1 is referred to as Ip1 and the capacitor C1 is referred to. A power recovery circuit 410 is modeled on the assumption that it is a power supply for supplying a V ₂ voltage, as shown in FIG. 6. In the circuit of FIG. 6, the resonance current IL1 flowing through the inductor L and the Y electrode voltage Vy of the panel capacitor Cp are obtained as Equations 1 and 2, respectively.

Referring to Equation 2, it can be seen that when the charging voltage V ₂ of the capacitor C1 is changed, the resonance peak voltage, that is, the voltage of the Y electrode of the panel capacitor is changed. In particular, it can be seen that when the charging voltage V ₂ of the capacitor C1 increases, the voltage Vy of the Y electrode of the panel capacitor Cp increases.

As a result, when the period T3 is lengthened, the magnitude of the voltage charged in the capacitor C1 increases, thereby increasing the voltage Vy of the Y electrode of the capacitor Cp. Therefore, when the load ratio of the plasma display panel 100 is large, increasing the period T3 makes it possible to compensate for the resonance peak voltage magnitude reduced by the load ratio, thereby stably causing sustain discharge. On the contrary, when the load ratio of the plasma display panel is small, the magnitude of the resonance peak voltage reduced by the load ratio becomes small. Therefore, the period T3 is shortened to prevent overdischarge, and when the load ratio is very small, the period T3 is eliminated. You may.

In the period T4, the switching element Ys is turned off. Then, as shown in FIG. 5C, a path is formed to the Y electrode, the inductor L, the diode D2, the switching element Yf, the capacitor C1, and the ground terminal 0 of the panel capacitor Cp (4). ). By this path (4), an LC resonant circuit is formed so that the voltage charged in the panel capacitor Cp is discharged so that the voltage of the Y electrode of the panel capacitor Cp decreases to near 0V voltage.

Next, in the period T5, the switching element Yg is turned on and the switching element Yf is turned off. Then, as shown in Fig. 6C, a path of the Y electrode-switching element Yg-ground terminal 0 of the panel capacitor Cp is formed (5). By this path (⑤), the Y electrode of the panel capacitor Cp is 0V. Maintained at voltage.

Although the preferred 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.

According to the present invention, when the sustain discharge pulse is applied to the scan electrode and the sustain electrode in the sustain period by using the power recovery circuit, stable sustain discharge is controlled by adjusting the voltage charged in the power recovery capacitor according to the load ratio of the plasma display panel. It can be raised. As a result, the image quality of the plasma display panel is improved.

Claims (15)

A plasma display panel including a first electrode and a second electrode, and In the sustain period, a voltage of the first electrode is increased through an inductor having a first end connected to a capacitor charged with a predetermined voltage and a second end connected to the first electrode, and then a first voltage at the first electrode. Driving circuit for reducing the voltage of the first electrode through the inductor and applying a second voltage to the first electrode Including; The driving circuit charges the capacitor during the first period of the period of applying the first voltage to the first electrode, And the first period increases as the screen load ratio of the plasma display panel increases. delete The method of claim 1, The drive circuit,  A first switching element electrically connected between a first power supply for supplying the first voltage and the first electrode; A second switching element electrically connected between a second power supply for supplying the second voltage and the first electrode; A third switching element electrically connected between the second end of the inductor and the capacitor, and A fourth switching element electrically connected between the second end of the first inductor and the capacitor More, And the first and fourth switching elements are turned on during the first period. delete delete The method of claim 3, The drive circuit, Turning on the third switching element to increase the voltage of the first electrode, Turn on the first switching device to apply the first voltage to the first electrode; Turning on the fourth switching element to reduce the voltage of the first electrode, And turning on the second switching element to apply the second voltage to the first electrode. delete A plurality of first electrodes, An inductor having a first end connected to the plurality of first electrodes, A capacitor charging a voltage between a first voltage and a second voltage lower than the first voltage, A first switching element connected between a first power supply for supplying the first voltage and the plurality of first electrodes; A second switching element connected between a second power supply for supplying the second voltage and the plurality of first electrodes; A third switching element connected between the second end of the inductor and the capacitor, A fourth switching element connected between the second end of the inductor and the capacitor, and In the sustaining period, the third switching device is turned on for a first period, the first switching device is turned on for a second period, and the fourth switching device is turned on for a third period. And setting the second switching element to a turn-on state for a fourth period, and setting the fourth switching element to a turn-on state for a fifth period of the second period. Including; And the control unit sets the fifth period to be longer as the screen load ratio increases. delete delete The method of claim 8, And a magnitude of the voltage charged in the capacitor in proportion to the fifth period. delete In the method of driving a plasma display device comprising a plurality of first electrodes, In the retention period, Increasing a voltage of the plurality of first electrodes through an inductor having a first end connected to a capacitor charging a predetermined voltage and a second end connected to the plurality of first electrodes, Applying a first voltage to the plurality of first electrodes, Charging a voltage to the capacitor during a first period of time during which the first voltage is applied to the plurality of first electrodes; Reducing the voltage of the first electrode through the inductor, and Applying a second voltage lower than the first voltage to the first electrode; Including; And driving the first period as the screen load ratio of the plasma display device increases. The method of claim 13, And a voltage is charged in the capacitor using a power supply for supplying the voltage. delete

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