KR100675323B1 - Method of Driving Plasma Display Panel - Google Patents

Abstract

The present invention relates to a method of driving a plasma display panel which can improve contrast ratio by reducing the amount of light generated during a reset period.

According to an exemplary embodiment of the present invention, a method of driving a plasma display panel includes applying a positive auxiliary waveform to an address electrode during a reset period, and applying a rising ramp waveform at which a voltage value gradually increases to a scan electrode, followed by the rising ramp waveform. And applying a falling ramp waveform in which the voltage value gradually decreases from the highest voltage value of the rising ramp pulse, and applying a positive pulse to the sustain electrode.

Description

Driving Method of Plasma Display Panel {Method of Driving Plasma Display Panel}             

1 is a perspective view showing a discharge cell structure of a conventional three-electrode AC surface discharge type plasma display panel.

2 is a diagram illustrating one frame of the plasma display panel.

3 is a diagram illustrating a driving waveform supplied to electrodes during a subfield period.

4 is a diagram showing the position of the wall voltage in the discharge cell in which the address discharge is generated.

5 is a diagram illustrating a process in which a sustain discharge is generated when a sustain pulse is supplied in a wall voltage state corresponding to the value shown in FIG. 4.

FIG. 6 is a diagram illustrating a position of a wall voltage formed by the sustain discharge of FIG. 5.

FIG. 7 is a diagram illustrating a change in wall voltage when an erase pulse is supplied in the wall voltage state of FIG. 6.

8 is a diagram showing the change of the cell voltage and the wall voltage when the rising ramp waveform is applied.

9 is a diagram illustrating a method of driving a plasma display panel according to a first embodiment of the present invention.

FIG. 10 is a diagram illustrating a change in cell voltage and wall voltage during a setup period in the driving method according to the first embodiment of the present invention.

11 is an optical waveform diagram measuring the amount of light generated during the reset period.

FIG. 12 is a diagram illustrating a change in cell voltage and wall voltage during a setdown period in the driving method according to the first embodiment of the present invention.

13 is a view showing a driving method according to a second embodiment of the present invention.

FIG. 14 is a diagram illustrating a change in cell voltage and wall voltage during a setup period in the driving method according to the second embodiment.

FIG. 15 is a diagram for describing timing of applying an auxiliary waveform in the driving method according to the second embodiment.

FIG. 16 is a diagram for describing timing of removing an auxiliary waveform in the driving method according to the second embodiment.

17 is a view showing a driving method according to a third embodiment of the present invention.

18 is a view showing a driving method according to a fourth embodiment of the present invention.

FIG. 19 is a view illustrating a change in cell voltage during a setup period in the driving method according to the fourth embodiment.

FIG. 20 is a diagram illustrating a change in cell voltage during a set down period in the driving methods according to the third and fourth embodiments.

<Description of Symbols for Main Parts of Drawings>

10: upper substrate 12Y, 12Z: transparent electrode

13Y, 13Z: bus electrode 14, 22: dielectric layer

16: protective film 18: lower substrate

24: partition 26: phosphor layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of driving a plasma display panel, and more particularly, to a method of driving a plasma display panel which can improve contrast ratio by reducing the amount of light generated during a reset period.

Plasma Display Panel (hereinafter referred to as "PDP") displays characters or graphics by emitting phosphors by 147 nm ultraviolet rays generated during discharge of He + Xe, Ne + Xe or He + Xe + Ne inert gas mixtures. The included image is displayed. Such a PDP is not only thin and easy to enlarge, but also greatly improved in quality due to recent technology development. In particular, the three-electrode AC surface discharge type PDP has advantages of low voltage driving and long life because wall charges are accumulated on the surface during discharge and protect the electrodes from sputtering caused by the discharge.

Referring to FIG. 1, a discharge cell of a three-electrode AC surface discharge type PDP includes a scan electrode Y and a sustain electrode Z formed on the upper substrate 10, and an address electrode formed on the lower substrate 18. X). Each of the scan electrode Y and the sustain electrode Z has a line width smaller than the line widths of the transparent electrodes 12Y and 12Z and the transparent electrodes 12Y and 12Z and is formed at one edge of the transparent electrode. 13Z).

The transparent electrodes 12Y and 12Z are usually formed on the upper substrate 10 by indium tin oxide (ITO). The metal bus electrodes 13Y and 13Z are usually formed of metals such as chromium (Cr) and formed on the transparent electrodes 12Y and 12Z to reduce voltage drop caused by the transparent electrodes 12Y and 12Z having high resistance. The upper dielectric layer 14 and the passivation layer 16 are stacked on the upper substrate 10 having the scan electrode Y and the sustain electrode Z side by side. In the upper dielectric layer 14, wall charges generated during plasma discharge are accumulated. The protective layer 16 prevents damage to the upper dielectric layer 14 due to sputtering generated during plasma discharge and increases emission efficiency of secondary electrons. As the protective film 16, magnesium oxide (MgO) is usually used.

The lower dielectric layer 22 and the partition wall 24 are formed on the lower substrate 18 on which the address electrode X is formed, and the phosphor layer 26 is coated on the surfaces of the lower dielectric layer 22 and the partition wall 24. The address electrode X is formed in the direction crossing the scan electrode Y and the sustain electrode Z. The partition wall 24 is formed in parallel with the address electrode X to prevent ultraviolet rays and visible light generated by the discharge from leaking to the adjacent discharge cells. The phosphor layer 26 is excited by ultraviolet rays generated during plasma discharge to generate visible light of any one of red, green, and blue. Inert mixed gas is injected into the discharge space provided between the upper and lower substrates 10 and 18 and the partition wall 24.

The PDP is time-divisionally driven by dividing one frame into several subfields having different number of emission times in order to implement grayscale of an image. Each subfield is divided into a reset period for initializing the full screen, an address period for selecting a scan line and selecting a cell in the selected scan line, and a sustain period for implementing gray scale according to the number of discharges.

Here, the reset period is divided into a setup period in which the rising ramp waveform is supplied and a set down period in which the falling lamp waveform is supplied. For example, when the image is to be displayed with 256 gray levels, as shown in FIG. 2, the frame period (16.67 ms) corresponding to 1/60 second is divided into eight subfields SF1 to SF8. Each of the eight subfields SF1 to SF8 is divided into a reset period, an address period and a sustain period as described above. The reset period and the address period of each subfield are the same for each subfield, while the sustain period is increased at a rate of 2 ⁿ (n = 0,1,2,3,4,5,6,7) in each subfield. .

3 shows driving waveforms of a PDP supplied to two subfields.

Referring to FIG. 3, the PDP is divided into a reset period for initializing the full screen, an address period for selecting a cell, and a sustain period for maintaining discharge of the selected cell.

In the reset period, the rising ramp waveform Ramp-up is applied to all the scan electrodes Y simultaneously. This rising ramp waveform (Ramp-up) causes a weak discharge in the cells of the full screen to generate wall charges in the cells. During the set-down period, after the ramp ramp is supplied, the ramp ramp down from the positive voltage lower than the peak voltage of the ramp ramp is applied to the scan electrodes (Y). It is applied at the same time. Ramp-down generates weak erase discharges in the cells, thereby eliminating unnecessary charges during wall charges and space charges generated by setup discharges, and uniformly distributing the wall charges required for address discharges in the cells of the full screen. Will remain.

In the address period, the negative scan pulse scan is sequentially applied to the scan electrodes Y, and the positive data pulse data is applied to the address electrodes X. As the voltage difference between the scan pulse and the data pulse and the wall voltage generated during the reset period are added, an address discharge is generated in the cell to which the data pulse is applied. Wall charges are generated in the cells selected by the address discharge.

Meanwhile, the positive polarity DC voltage of the sustain voltage level Vs is supplied to the sustain electrodes Z during the set down period and the address period.

In the sustain period, sustain pulses sus are alternately applied to the scan electrodes Y and the sustain electrodes Z. FIG. Then, the cell selected by the address discharge is sustained in the form of surface discharge between the scan electrode (Y) and the sustain electrode (Z) whenever the sustain pulse (sus) is applied while the wall voltage and the sustain pulse (sus) in the cell are added. Discharge occurs. Finally, after the sustain discharge is completed, an erase ramp waveform (erase) having a small pulse width is supplied to the sustain electrode (Z) to erase wall charges in the cell.

The principle of generation of wall charges and discharges during the sustain period will be described in detail using a hexagonal voltage curve as shown in FIG. 4. Here, the Vt close curve is used as a method for measuring the discharge generation principle and the voltage margin of the PDP.

In FIG. 4, the hexagonal area inside the voltage curve is an area where wall charges inside the discharge cell are distributed, and no discharge is generated in this area. In addition, Y (−) represents a direction in which the wall voltage moves when a negative voltage is applied to the scan electrode Y. Similarly, Y (+), X (+), X (-), Z (+), and Z (-) each have a negative or positive voltage applied to the scan electrode Y or the sustain electrode Z. Indicates the direction in which the wall voltage moves.

The Vtxy displayed in the first quadrant opposite discharge region of the voltage curve graph represents the voltage at which discharge is started between the address electrode X and the scan electrode Y. FIG. In other words, the straight line representing the first quadrant opposite discharge region of the voltage curve graph is set to a length equal to the voltage at which the discharge between the address electrode X and the scan electrode Y is started. The Vtzy displayed in the quadrant surface discharge region of the voltage curve graph represents the voltage at which discharge starts between the sustain electrode Z and the scan electrode Y. FIG. Similarly, Vtxz, Vtzx, Vtyz, and Vtyx each represent a discharge start voltage between the electrodes.

Referring to the operation of the sustain period, the wall charges in the discharge cells in which the address discharge is generated are located in the third quadrant of the graph as shown in FIG. Subsequently, when the positive sustain pulse is applied to the scan electrode Y as shown in FIG. 3, the voltages of the wall charges positioned in the third quadrant and the voltage of the positive sustain pulse are added to the third quadrant of the graph as shown in FIG. 5. It is moved via the located surface discharge area (that is, moved to the Y (+) side). At this time, in the discharge cells, sustain discharge is generated between the scan electrode (Y) and the sustain electrode (Z).

After the sustain discharge is generated, the wall charges are located in the first quadrant of the graph as shown in FIG. Then, the voltage of the wall charges positioned in the first quadrant and the voltage of the positive sustain pulse are added together by the positive sustain pulse applied to the sustain electrode Z. The voltage value is the surface discharge region located in the first quadrant as shown in FIG. Is moved via (i.e., moved to the Z (+) side). At this time, sustain discharge is generated between the sustain electrode Y and the scan electrode Y in the discharge cells. In practice, the PDP generates a predetermined number of sustain discharges by repeating this process during the sustain period.

After the sustain discharge is completed, the wall voltage is located at the point A0 of the first quadrant of the graph as shown in FIG. 7 (that is, the last sustain pulse is applied to the scan electrode Y), and then the erase ramp waveform is applied to the sustain electrode Z. (erase) is supplied. When the erase ramp waveform (erase) having the magnitude of Vc is supplied to the sustain electrode Z, the cell voltage is moved via the surface discharge region of the first quadrant of the graph (that is, moved to the Z (+) side) as shown in FIG. . Here, when the cell voltage passes through the quadrant surface discharge area of the graph, the wall voltage moves at a slope of 1/2. That is, it is moved to the A1 point.

That is, after the erase discharge is completed, the wall charges are moved to the position of A1 as shown in FIG. 7. The wall charges of the cells in which the sustain discharge has not been generated (that is, the cells in which the address discharge has not occurred in the previous subfield) maintain the A1 position in the sustain period (that is, the wall charges of the cells in which the address discharge has not occurred). They maintain the position of A1 from the reset period of the previous subfill to the reset period of the next subfield). In other words, applying the erase ramp waveform after the sustain discharge is to increase the uniformity of the discharge cells before the reset period.

The reset period of the next subfield following the sustain period is divided into a setup period and a setdown period.

Referring to FIG. 8, a ramp lamp waveform Ramp-up is supplied to the scan electrodes Y during the setup period. When the rising ramp waveform Ramp-up is supplied to the scan electrodes Y, the cell voltage is moved from A1 through the surface discharge region of the three quadrants (ie, moved to the Y (+) side). Here, when the cell voltage reaches the boundary value of the surface discharge region in the three quadrants of the graph, surface discharge occurs between the scan electrode Y and the sustain electrode Z. Ramp-up is continuously applied up to the voltage of Vy2, but after the surface discharge occurs, the absolute value of the voltage in the cell does not change as much as the voltage size of Vy2 after the surface discharge occurs. It descends by the size of Vy2 'along the boundary of the discharge area. This is because there is no change in voltage between the scan electrode Y and the sustain electrode Z where surface discharge is occurring, but the potential difference with the address electrode X due to the negative charge (-) accumulated in the scan electrode Y. Means to be added.

The movement of the cell voltage along the boundary of the surface discharge region means that the discharge occurs, and therefore, the wall voltage changes from the position of A1 to the position of C1 due to the generation of wall charge.

On the other hand, when the cell voltage which changes along the boundary value of the surface discharge area of the three quadrants reaches the point F of discharge discharge voltage between the scan electrode Y and the sustain electrode Z, the scan electrode Y and the address electrode X are An opposite discharge occurs between them.

From the time when the opposite discharge occurs, the surface discharge and the opposite discharge occur simultaneously in the discharge space. Since the wall charge is also formed in the address electrode X, the wall voltage changes from the position of C1 to C2 with the magnitude of the slope 1.

As described above, according to the conventional driving method of the PDP, in addition to the surface discharge generated between the scan electrode (Y) and the sustain electrode (Z) after a predetermined time in the process of applying the rising ramp waveform (Ramp-up) during the setup period, the scan electrode (Y) ) And an opposite discharge occur between the address electrode (X).

The purpose of the reset period is not to represent the gradation but to initialize the discharge cells and to generate an appropriate amount of wall charge on the scan electrode (Y). Therefore, since it is not a discharge for expressing gradation, outflow of light by the discharge is unnecessary. The lower the luminance of light emitted in the reset period, the greater the contrast difference in expressing the low and high grays when the discharge for expressing the grays occurs, so the contrast becomes better.

However, in addition to the surface discharge between the scan electrode (Y) and the sustain electrode (Z) during the reset period, the amount of light emitted during the reset period during which the counter discharge occurs between the scan electrode (Y) and the address electrode (X) is increased accordingly. Is lowered.

Accordingly, it is an object of the present invention to provide a driving method of a PDP capable of improving contrast.

In order to achieve the above object, the driving method of the PDP according to the present invention applies a rising ramp waveform in which a voltage value gradually increases to a scan electrode during a reset period, and applies a falling ramp waveform in which the voltage value gradually decreases following the rising ramp waveform. And applying an auxiliary waveform having a positive polarity to the address electrode.

The auxiliary waveform is characterized by having a voltage value equal to or less than the absolute value of the lower limit of the falling ramp waveform.

The auxiliary waveform is applied before the rising ramp waveform is applied or simultaneously with the rising ramp waveform or while the rising ramp waveform is being applied.

The auxiliary waveform is removed simultaneously with the falling ramp waveform or while the falling ramp waveform is applied.

The timing of applying the auxiliary waveform is applied before the timing of exceeding the discharge start voltage when the auxiliary waveform is applied to the cell voltage value changed by the rising ramp waveform.

The time for removing the auxiliary waveform is removed before the time when the sum of the voltage due to the falling ramp waveform and the voltage due to the auxiliary waveform exceeds the discharge start voltage.

And applying a positive pulse to the sustain electrode while the falling ramp waveform is applied.

The driving method of the PDP according to another embodiment of the present invention applies a rising ramp waveform in which the voltage value gradually increases to the scan electrode during the reset period, and applies a falling ramp waveform in which the voltage value gradually decreases after the rising ramp waveform. And applying an auxiliary rising ramp waveform to the address electrode.

The highest upper limit of the auxiliary ramp ramp waveform has a voltage value equal to or less than the absolute value of the lower limit of the ramp ramp waveform.

The rising ramp waveform is applied before the rising ramp waveform is applied or simultaneously with the rising ramp waveform, or while the rising ramp waveform is applied.

The auxiliary waveform is removed simultaneously with the falling ramp waveform or while the falling ramp waveform is applied.

The timing of applying the auxiliary rising ramp waveform is applied before the timing of exceeding the discharge start voltage when the auxiliary waveform is applied to the cell voltage value changed by the rising ramp waveform.

The time for removing the auxiliary waveform is removed before the time when the sum of the voltage due to the falling ramp waveform and the voltage due to the auxiliary waveform exceeds the discharge start voltage.

While the falling ramp waveform is applied, a positive pulse is further applied to the sustain electrode.

Other objects and features of the present invention in addition to the above objects will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 9 to 20.

9 is a driving waveform showing the driving method of the PDP according to the first embodiment of the present invention.

Referring to FIG. 9, the driving method of the PDP according to the first embodiment of the present invention is divided into a reset period for initializing the full screen, an address period for selecting a cell, and a sustain period for maintaining discharge of the selected cell. do.

The reset period is divided into a setup period and a setdown period.

In the setup period, the positive auxiliary waveform Va is applied to the address electrodes X at the time T0.

Subsequently, a ramp up waveform Ramp-up is simultaneously applied to the scan electrodes Y at the time T1. This rising ramp waveform (Ramp-up) causes a weak discharge in the cells of the full screen to generate wall charges in the cells. Even when the rising ramp waveform Ramp-up rising to the voltage Vy2 is applied, discharge occurs between the scan electrode Y and the address electrode X due to the positive auxiliary waveform Va applied to the address electrodes X. I never do that.

During the set-down period, after the ramp ramp is supplied, the ramp ramp down from the positive voltage lower than the peak voltage of the ramp ramp is applied to the scan electrodes (Y). It is applied at the same time. Ramp-down generates weak erase discharges in the cells, thereby eliminating unnecessary charges during wall charges and space charges generated by setup discharges, and uniformly distributing the wall charges required for address discharges in the cells of the full screen. Will remain.

The process of generating the discharge during the reset period will be described in detail using the voltage curve Vt close curve of the discharge cell.

Referring to FIG. 10, after the sustain discharge is completed, the wall charges of the on cells are located at the point A1 on the Vxy axis.

Subsequently, at the time T0 of the reset period, the positive auxiliary waveform Va is applied to the address electrodes X. The cell voltage changes in the X (+) direction along the Vxy axis due to the auxiliary waveform Va applied to the address electrodes X. The magnitude of the auxiliary waveform Va is set equal to or smaller than the absolute value of the lower limit value of the ramp ramp down applied to the scan electrodes Y during the set down period, that is,? -Vy ?. This is because when the magnitude of the auxiliary waveform Va is greater than the magnitude of -Vy, erroneous discharge may occur depending on the initial condition of the discharge cell.

At the time point T1, a ramp-up ramp ramp-up is applied to the scan electrodes Y in which the voltage value gradually increases at the positive voltage. Ramp-up ramp up to the voltage value of Vy2. When the rising ramp waveform Ramp-up is applied to the scan electrodes Y, the cell voltage of the discharge cell changes in the V (+) direction. The changing cell voltage falls along the boundary surface of the surface discharge region while generating a weak discharge when the boundary line of Vtyz, which is the surface discharge start voltage between the scan electrode Y and the sustain electrode Z, is located in the third quadrant of the voltage curve. do. The rising ramp waveform Ramp-up is applied at the point A2 instead of the point A1, so that the cell voltage does not reach the point F even when the rising ramp waveform Ramp-up is applied up to Vy2. That is, when the rising ramp waveform Ramp-up is applied, only the surface discharge between the scan electrode Y and the sustain electrode Z occurs, and the opposite discharge does not occur between the scan electrode Y and the sustain electrode Z. do. Therefore, the amount of light generated by the reset discharge in the reset period can be reduced.

This can be seen by looking at the change of wall voltage. Looking at the change in the wall voltage during the set-down period, if discharge occurs in the surface discharge boundary of the third quadrant during the ramp-up, the wall voltage changes due to the generation of wall charges. When the surface discharge occurs, the wall voltage moves from the A1 point to the Vw1 point with a half slope. The change of the existing wall voltage is changed from the point A1 to the point Vw2 with the slope of 1/2, and when the cell voltage reaches the point F, opposite discharge occurs, and then the ramp ramp is supplied. During this period, the slope of 1 changes to the point Vw3. That is, it can be seen that the amount of change in wall voltage is also reduced. The wall voltage is a potential difference generated by the wall charge generated when the discharge occurs, and the small amount of change in the wall voltage means that the small amount of change in the wall charge is small. Therefore, it can be seen that the less amount of light generated by the discharge is generated by the less discharge that generates the wall charge.

In addition, referring to FIG. 11, which is experimental data measuring the amount of light generated during an actual reset period, the amount of light generated during the reset period is the experimental value (b) according to the driving method according to the present invention. You can see that it is much smaller.

In the set-down period following the setup period, a ramp down ramp waveform (Ramp-down) is applied to the scan electrode (Y) at the time T2. At the same time, a positive voltage is applied to the sustain electrode Z. In the process of applying the ramp ramp down to the scan electrode (Y), the change in the cell voltage from the scan electrode (Y) to the sustain electrode (Z) until the surface discharge occurs is A5. .

Referring to FIG. 12, when the ramp ramp down is applied to the scan electrode Y, the cell voltage moves from the A3 point to the A4 point. At the same time, a positive voltage is applied to the sustain electrode Z so that the cell voltage is shifted in the Vzy axis direction, that is, in the Z (+) direction, to change to the A5 point. Since the ramp ramp down and the ramp ramp are applied simultaneously to the scan electrode Y, the cell voltage changes from A3 to A5 until the surface discharge occurs in the setdown period. . Since a weak discharge occurs between the scan electrode (Y) and the sustain electrode (Z) while the ramp ramp is continuously applied, the potential difference no longer occurs, and due to the wall charges formed on the scan electrode (Y). Since the potential difference between the scan electrode Y and the address electrode X becomes larger, the cell voltage rises to the point A6 along the surface discharge voltage boundary of the first quadrant.

While the cell voltage is changed from the A5 to the A6 point, weak discharge is generated between the scan electrode Y and the sustain electrode Z. The wall voltage changes due to the generation of wall charges due to the discharge. That is, at the end of the setup period, the wall voltage corresponding to the point of Vw1 returns to the point A1 while changing with a slope of 1/2.

In the address period after the reset period, the negative scan pulse scan is sequentially applied to the scan electrodes Y and the positive data pulse data is applied to the address electrodes X. As the voltage difference between the scan pulse and the data pulse and the wall voltage generated during the reset period are added, an address discharge is generated in the cell to which the data pulse is applied. Wall charges are generated in the cells selected by the address discharge.

On the other hand, the positive pole DC voltage of the sustain voltage level Vs is supplied to the sustain electrodes Z during the address period.

In the sustain period, sustain pulses sus are alternately applied to the scan electrodes Y and the sustain electrodes Z. FIG. Then, the cell selected by the address discharge is sustained in the form of surface discharge between the scan electrode (Y) and the sustain electrode (Z) whenever the sustain pulse (sus) is applied while the wall voltage and the sustain pulse (sus) in the cell are added. Discharge occurs.

13 is a diagram illustrating a method of driving a PDP according to a second embodiment of the present invention.

Referring to FIG. 13, the driving method of the PDP according to the second embodiment of the present invention is divided into a reset period for initializing the full screen, an address period for selecting a cell, and a sustain period for maintaining discharge of the selected cell. do.

In this embodiment, description of the address period and the sustain period which are substantially the same as the above-described embodiment will be omitted.

The reset period is divided into a setup period and a setdown period.

The driving method of the PDP according to the second embodiment of the present invention will be described with reference to FIG. 14 showing a change in the voltage value on the voltage curve.

In the setup period, the rising ramp waveform Ramp-up is simultaneously applied to the scan electrodes Y at the time point T0. The cell voltage of the discharge cell starts to change in the Y (+) direction by the rising ramp waveform Ramp-up applied to the scan electrode Y.

At the time T1, the auxiliary waveform Va of the rising ramp waveform Ramp-up is applied to the address electrodes X. When the auxiliary waveform Va of the rising ramp waveform Ramp-up is applied to the address electrodes X, the cell voltage that changes in the Y (+) direction changes from the A2 point to the A3 point, that is, in the X (+) direction. do.

The cell voltage continuously changes in the Y (+) direction at the A3 point due to the ramp ramp up to the voltage of Vy2 applied to the scan electrode Y, and then the scan electrode Y and the sustain in three quadrants When the boundary value of the surface discharge area of the electrode reaches, weak discharge occurs. Since the weak discharge is caused by the rising ramp waveform (Ramp-up), the discharge continues without a change in the voltage difference between the scan electrode (Y) and the sustain electrode (Z), so that the cell voltage falls along the boundary of the surface discharge voltage. do. By applying the auxiliary waveform Va to the address electrode X at the time T1 while the ramp ramp is applied, the cell voltage is increased in the Vxy direction, that is, in the X (+) direction. Even when a ramp waveform rising to Vy2 is applied to Y), the cell voltage does not change to the point F which causes opposite discharge between the scan electrode Y and the address electrode X. FIG. Therefore, only the surface discharge occurs during the setup period and the opposite discharge can be prevented from occurring so that the amount of light generated during the setup period can be reduced.

This can be seen by examining the change in the wall voltage shown in FIG. 10 as in the above-described embodiment. In other words, it can be seen that the amount of change in the wall voltage is reduced as compared with the conventional driving method. The wall voltage is a potential difference generated by the wall charge generated when the discharge occurs, and the small amount of change in the wall voltage means that the small amount of change in the wall charge is small. Therefore, it can be seen that the less amount of light generated by the discharge is generated by the less discharge that generates the wall charge.

Since the amount of light generated during the reset discharge is not for gray scale expression, the amount of light generated at this time can be minimized to increase the contrast ratio. That is, the contrast can be improved by improving the contrast ratio.

As in the second embodiment, the discharge cell is strongly discharged due to the application of the auxiliary waveform Va when the positive auxiliary waveform Va is applied to the address electrode X while the rising ramp waveform is applied during the setup period. Set to the point in time when this does not occur. If you look at this in detail,

Referring to FIG. 15, it is common that the voltage curve having the discharge start voltage as a boundary value does not form a right angle at the intersection of the surface discharge area and the opposite discharge area in the first and third quadrants as in the above-described embodiment. . This is because the discharge start voltage changes according to various panel elements related to the discharge characteristics, so the shape of the voltage curve also changes accordingly. The reason why the voltage curve is distorted is that the electric field between the pair of sustain electrodes is distorted according to the voltage applied to the address electrode even in the surface discharge generated between the scan electrode and the sustain electrode. Therefore, the higher the voltage applied to the address electrode to the positive voltage, the lower the surface discharge start voltage, and the lower the voltage applied to the address electrode to the negative voltage, the higher the surface discharge start voltage. Due to this shape, the left and right sides of the voltage curve appear to be bent.

When the rising ramp waveform Ramp-up is applied to the scan electrode Y under the condition of the discharge cell having such a voltage curve, the cell voltage changes in the Y (+) direction. When the auxiliary waveform Va is applied to the address electrode X at the time T1 'after the rising ramp waveform Ramp-up is applied, the cell voltage moves in the X (+) direction. At this time, when the rising ramp waveform (Ramp-up) is in the surface discharge boundary or closely to the surface discharge boundary, when the positive auxiliary waveform Va is applied to the address electrode X, the cell voltage is instantaneously discharged. It is out of the value and strong discharge occurs. When such strong discharge occurs in the reset period, erroneous discharge occurs in the sustain period, and therefore, in order to prevent such strong discharge, the auxiliary waveform Va applied to the address electrode is applied before the time point T1. That is, when the auxiliary waveform Va is applied, the cell voltage caused by the auxiliary waveform Va is applied at a time point that does not deviate from the boundary of the voltage curve.

In addition, when the auxiliary waveform Va is removed in the process of applying the ramp ramp down, the auxiliary cell Va is removed before the point where the strong discharge occurs. Looking at this in detail:

Referring to FIG. 16, in the set down period, the cell voltage changes to the point A4 due to the falling ramp waveform applied to the scan electrode Y. FIG. In addition, the cell voltage varies from A4 to A5 due to the positive polarity applied to the sustain electrode Z. Point A5 is the discharge start voltage, and surface discharge occurs at this point, and the cell voltage rises in the X (+) direction along the surface discharge region of the first quadrant while the falling lamp waveform is applied. In addition, the cell voltage further increases by Va due to the positive auxiliary waveform Va applied to the address electrode X. FIG. In this process, if the auxiliary waveform Va is applied up to the time point T4 '(any time after the time point T4), the cell voltage is the opposite discharge area which is the discharge start voltage between the scan electrode Y and the sustain electrode Z. To reach. In this case, too, strong discharge occurs between the scan electrode (Y) and the address electrode (X), which causes a false discharge. Therefore, the auxiliary waveform Va applied to the address electrode X should be removed at a time point T4 when the cell voltage does not deviate from the voltage curve in the setdown period.

17 is a diagram illustrating a method of driving a PDP according to a third embodiment of the present invention.

Referring to FIG. 17, a driving method of a PDP according to a third embodiment of the present invention is divided into a reset period for initializing a full screen, an address period for selecting a cell, and a sustain period for maintaining discharge of the selected cell. do.

The reset period is divided into a setup period and a setdown period.

In the setup period, the rising ramp waveform auxiliary waveform Va is applied to the address electrodes X at the time T0.

Subsequently, a ramp up waveform Ramp-up is simultaneously applied to the scan electrodes Y at the time T1. This rising ramp waveform (Ramp-up) causes a weak discharge in the cells of the full screen to generate wall charges in the cells. Discharge is generated between the scan electrode Y and the address electrode X due to the auxiliary waveform Va of the rising ramp waveform applied to the address electrodes X even when the rising ramp waveform Ramp-up rising to the voltage of Vy2 is applied. This does not happen.

During the set-down period, after the ramp ramp is supplied, the ramp ramp down from the positive voltage lower than the peak voltage of the ramp ramp is applied to the scan electrodes Y. It is applied at the same time. Ramp-down generates weak erase discharges in the cells, thereby eliminating unnecessary charges during wall charges and space charges generated by setup discharges, and uniformly distributing the wall charges required for address discharges in the cells of the full screen. Will remain.

According to the driving method of the PDP according to the present embodiment, by using the auxiliary waveform Va applied to the address electrode X, a ramp waveform in which strong discharge does not occur, it is possible to prevent the occurrence of false discharge and to secure driving timing margin. can do. FIG. 18 is a view showing an embodiment in which the auxiliary waveform Va applied to the address electrode X is applied at a time interval of a predetermined period after the rising ramp waveform Ramp-up is applied. Referring to FIG. 19, which is a diagram illustrating a change in cell voltage according to the driving waveform shown in FIG. 18, it is as follows.

18 is a diagram illustrating a method of driving a PDP according to a fourth embodiment of the present invention.

18 and 19, the driving method of the PDP according to the second embodiment of the present invention is a reset period for initializing the full screen, an address period for selecting a cell, and a sustain period for maintaining the discharge of the selected cell. Driven by dividing into.

In this embodiment, description of the address period and the sustain period which are substantially the same as the above-described embodiment will be omitted.

The reset period is divided into a setup period and a setdown period.

In the setup period, the rising ramp waveform Ramp-up is simultaneously applied to the scan electrodes Y at the time point T0. Due to the ramp ramp up applied to the scan electrode Y, the cell voltage of the discharge cell changes from the voltage located at the A1 point to the A2 point. That is, it changes in the Y (+) direction.

At the time T1, the auxiliary waveform Va of the rising ramp waveform Ramp-up is applied to the address electrodes X. By the auxiliary waveform Va applied to the address electrode X, the cell voltage changes from the A2 point to the A3 point, that is, in the X (+) direction. In the vicinity of the surface discharge boundary of the third quadrant, when the positive spherical pulse was applied as the auxiliary waveform, strong discharge occurred as shown in FIG. 15. However, when the auxiliary waveform Va is applied as a ramp waveform, the cell voltage gradually rises and reaches a point A3, which is the boundary of surface discharge, and causes a weak discharge. Due to the wall charge generated by the weak discharge, the cell voltage falls below the discharge start voltage and is discharged when the discharge start voltage is again caused by the rising ramp waveform. As this process is repeated, strong discharge does not occur and weak discharge occurs, and the cell voltage changes in the A4 'direction. However, since the ramp ramp up of a voltage value larger than the auxiliary waveform Va applied to the address electrode X is applied to the scan electrode Y, the cell voltage actually changes to the point A4.

In this case, when the auxiliary waveform Va is used as the ramp waveform, the cell voltage is caused by the rising ramp waveform Ramp-up applied to the scan electrode Y, and the surface discharge boundary between the scan electrode Y and the sustain electrode Z is applied. Even when close to the teeth, strong discharge does not occur even when the auxiliary waveform Va is applied, thereby ensuring driving reliability and driving margin. However, in order to achieve higher driving reliability, the time of applying the auxiliary waveform Va of the ramp waveform is set to be applied before the time of surface discharge occurs at the time of applying the auxiliary waveform Va.

On the other hand, such a driving margin is efficient even when the auxiliary waveform Va is removed.

Referring to FIG. 20, in the set down period, the cell voltage changes to the point A5 due to the falling ramp waveform applied to the scan electrode Y. FIG. In addition, the cell voltage varies from A5 to A6 due to the positive voltage applied to the sustain electrode Z. FIG. The point A6 is the discharge start voltage, and surface discharge occurs at this point. The cell voltage rises in the X (+) direction along the surface discharge region of the first quadrant while the falling lamp waveform is applied. In addition, the cell voltage further increases by Va due to the auxiliary waveform Va of the ramp waveform applied to the address electrode X. FIG. When the auxiliary waveform Va is applied to the time point T4, when the discharge start voltage between the scan electrode Y and the sustain electrode Z is reached by the cell voltage rising by Va, the discharge start voltage is instantaneously when the square wave is used. Because of this, strong discharge occurs. However, when the ramp waveform is used as the auxiliary waveform Va, when the auxiliary waveform Va is applied above the time point T4, weak discharge occurs when the cell voltage reaches the surface discharge boundary, and thus wall charge is generated. The cell voltage is lowered. In addition, since the auxiliary waveform Va is a ramp waveform, the cell voltage again becomes equal to or higher than the discharge start voltage to start discharging, and this process is repeated. As described above, when the auxiliary waveform Va is applied as a ramp waveform, even when the timing of removing the auxiliary waveform Va is late, strong discharge does not occur, thereby increasing the driving timing margin. However, in order to increase the driving margin and the reliability of the driving, as in the second embodiment, the timing of removing the auxiliary waveform Va of the ramp waveform is determined by the auxiliary waveform Va, so that the cell voltage is reduced by the scan electrode Y and the address electrode. This can be done before the point where no opposite discharge occurs between (X).

As described above, according to the driving method of the plasma display panel according to the present invention, the contrast ratio can be improved by reducing the amount of light by preventing the opposite discharge occurring between the scan electrode and the address electrode during the reset period.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (14)

One frame is divided into a plurality of subfields, and at least one of the subfields is time-divisionally driven with a reset period for initializing a cell, an address period for selecting a discharge cell, and a sustain period for generating sustain discharge. In the driving method of the display panel, The reset period is Applying a ramp ramp waveform whose voltage value gradually rises in the positive polarity to the scan electrode, and applying a ramp ramp waveform whose voltage value gradually decreases following the ramp ramp waveform; Applying a positive auxiliary waveform to an address electrode, supplying a part of the auxiliary waveform while a rising ramp waveform is applied to the scan electrode and supplying another part of the auxiliary waveform while a positive pulse is applied to the sustain electrode; Include, And wherein the auxiliary waveform has a voltage value equal to or less than an absolute value of a lower limit of the falling ramp waveform. delete The method of claim 1, And wherein the auxiliary waveform is applied before the rising ramp waveform is applied or simultaneously with the rising ramp waveform or while the rising ramp waveform is being applied. The method of claim 3, wherein And the auxiliary waveform is removed at the same time as the falling ramp waveform or removed while the falling ramp waveform is applied. The method of claim 3, wherein And when the auxiliary waveform is applied to the cell voltage value changed by the rising ramp waveform, before the time when the auxiliary waveform is exceeded when the discharge start voltage is exceeded. The method of claim 4, wherein And the time for removing the auxiliary waveform is removed before the time when the sum of the voltage due to the falling ramp waveform and the voltage due to the auxiliary waveform exceeds the discharge start voltage. The method of claim 1, And applying a positive pulse to a sustain electrode while the falling ramp waveform is applied. One frame is divided into a plurality of subfields, and at least one of the subfields is time-divisionally driven with a reset period for initializing a cell, an address period for selecting a discharge cell, and a sustain period for generating sustain discharge. In the driving method of the display panel, The reset period is Applying a ramp ramp waveform whose voltage value gradually rises in the positive polarity to the scan electrode, and applying a ramp ramp waveform whose voltage value gradually decreases following the ramp ramp waveform; Applying a positive pulse to a sustain electrode while the falling ramp waveform is applied; The auxiliary rising ramp waveform is applied to the address electrode, while a part of the auxiliary rising waveform is supplied while the rising ramp waveform is applied to the scan electrode, and another part of the auxiliary rising waveform is applied while the positive pulse is applied to the sustain electrode. And driving the plasma display panel. The method of claim 8, And a maximum upper limit of the auxiliary rising ramp waveform has a voltage value that is equal to or smaller than an absolute value of the lower limit of the falling ramp waveform. The method of claim 8, Wherein the rising ramp waveform is applied before the rising ramp waveform is applied or simultaneously with the rising ramp waveform, or is applied while the rising ramp waveform is being applied. The method of claim 8, And the auxiliary waveform is removed at the same time as the falling ramp waveform or removed while the falling ramp waveform is applied. The method of claim 10, And when the auxiliary waveform is applied to the cell voltage value changed by the rising ramp waveform, before the discharge start voltage is exceeded. The method of claim 11, And the time for removing the auxiliary waveform is removed before the time when the sum of the voltage due to the falling ramp waveform and the voltage due to the auxiliary waveform exceeds the discharge start voltage. delete

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