KR100622697B1 - Driving Method for Plasma Display Panel - Google Patents

Abstract

The present invention relates to a method of driving a plasma display panel. The driving method of the plasma display panel of the present invention is a driving method for expressing an image gray level of a plasma display panel having a scan electrode (Y electrode), a sustain electrode (Z electrode), and an address electrode (X electrode) by a subfield. At least one of the subfields included in one frame, the opposite discharge is generated between the scan electrode and the address electrode in the sustain period. According to the present invention, it is possible to reduce the distribution distortion of the wall charge between the on cell and the off cell by improving the waveform applied to the sustain period.

Plasma Display Panel, Dark Image, Driving Method, Sustain Section, Counter Discharge, Wall Charge, Distribution Distortion

Description

Driving method for plasma display panel {Driving Method for Plasma Display Panel}

1 is a diagram showing the structure of a typical plasma display panel.

2 is a diagram illustrating a method of expressing image gray scale in a conventional plasma display panel.

3 is a view illustrating a driving waveform according to a driving method of a conventional plasma display panel.

4 is a view for explaining in more detail the driving waveform in the sustain period of the driving waveform shown in FIG.

5A to 5B are views for explaining discharge in discharge cells of a conventional plasma display panel according to a driving waveform in the sustain period shown in FIG.

6A and 6B are diagrams for explaining distribution of wall charges in discharge cells according to driving waveforms in a conventional sustain period.

7 illustrates driving waveforms for explaining a method of driving a plasma display panel according to a first embodiment of the present invention;

FIG. 8 is an enlarged view of a part of the last subfield in the driving waveform shown in FIG. 7; FIG.

9A to 9C conceptually show wall charge distribution in discharge cells when the driving waveform shown in FIG. 8 is applied.

FIG. 10 is a view for explaining a distribution of wall charges in a discharge cell in a reset section of a next subfield after a driving waveform is applied in the method of driving a plasma display panel according to an embodiment of the present invention; FIG.

11 is a view for explaining a method of driving a plasma display panel according to a second embodiment of the present invention;

12 is a view for explaining a method of driving a plasma display panel according to a third embodiment of the present invention;

13 is a view for explaining a method of driving a plasma display panel according to a fourth embodiment of the present invention;

<Explanation of symbols for the main parts of the drawings>

100: upper substrate 101: scanning electrode

102 sustain electrode 103 dielectric layer

104: protective layer 110: lower substrate

111: partition 112: address electrode

113 phosphor 114 white dielectric

The present invention relates to a plasma display panel, and more particularly, to a method of driving a plasma display panel which reduces an afterimage by improving a waveform applied to a sustain period.

In general, a plasma display panel is a partition wall formed between an upper substrate and a lower substrate to form one unit cell, and each cell includes neon (Ne), helium (He), or a mixture of neon and helium (Ne + He) and An inert gas containing the same main discharge gas and a small amount of xenon is filled. When discharged by a high frequency voltage, the inert gas generates vacuum ultraviolet rays and emits phosphors formed between the partition walls to realize an image. Such a plasma display panel has a spotlight as a next generation display device because of its thin and light configuration.

1 illustrates a structure of a general plasma display panel. As shown, the plasma display panel is coupled in parallel with the upper substrate 100, which is the display surface on which the image is displayed, and the lower substrate 110 forming the rear surface with a predetermined distance therebetween.

The upper substrate 100 is made of a scan electrode 101 and a sustain electrode 102, that is, a transparent electrode (a) formed of a transparent ITO material and a metal material to mutually discharge and maintain light emission of the cells in one discharge cell. The scan electrode 101 and the sustain electrode 102 provided as the bus electrode b are formed in pairs. The scan electrode 101 and the sustain electrode 102 are covered by one or more dielectric layers 103 which limit the discharge current and insulate the electrode pairs, and the magnesium oxide upper surface of the dielectric layer 103 is easy to facilitate the discharge conditions. A protective layer 104 on which (MgO) is deposited is formed.

The lower substrate 110 is arranged in such a manner that a plurality of discharge spaces, that is, strips 111 of a stripe type (or well type) for forming discharge cells are maintained in parallel. In addition, a plurality of address electrodes 112 which perform address discharge to generate vacuum ultraviolet rays are arranged in parallel with the partition wall 111. On the upper side of the lower substrate 110, R, G, and B phosphors 113 which emit visible light for image display during address discharge are coated. A white dielectric 114 is formed between the address electrode 112 and the phosphor 113 to protect the address electrode 112 and reflect visible light emitted from the phosphor 113 to the upper substrate 100.

A method of expressing image gradation of a conventional plasma display panel having such a structure will be described with reference to FIG. 2.

2 is a diagram illustrating a method of expressing image gray scale in a conventional plasma display panel. As shown, the image gradation of the plasma display panel is driven by dividing one frame into several subfields having different emission counts. Each subfield is divided into a reset section for uniformly generating a discharge, an address section for selecting a discharge cell, and a sustain section for implementing gray levels according to the number of discharges. For example, when displaying an image with 256 gray levels, a frame section (16.67 ms) corresponding to 1/60 second is divided into eight subfields. In addition, each of the eight subfields is subdivided into a reset and address period and a sustain period. Here, the reset section and the address section of each subfield are the same for each subfield, while the sustain section increases at a rate of 2n (n = 0,1,2,3,4,5,6,7) in each subfield. do. Referring to the driving waveform according to the driving method of the plasma display panel as shown in FIG.

3 is a diagram illustrating a driving waveform according to a driving method of a conventional plasma display panel. As shown, the plasma display panel includes a reset section for initializing the entire screen, an address section for selecting a cell to be discharged, a sustain section for maintaining the discharge of the selected cell, and an erasing section for erasing wall charges in the discharged cell. Driven by dividing into.

In the reset section, the rising ramp waveform Ramp-up is simultaneously applied to all the Y electrodes (scan electrodes) in the setup section. This rising ramp waveform causes discharge to occur in the cells of the full screen. By this setup discharge, positive wall charges are accumulated on the X electrode (address electrode) and Z electrode (sustain electrode), and negative wall charges are accumulated on the Y electrode. During the set-down period, after the rising ramp waveform is supplied, the ramp ramp starts to fall from the positive voltage lower than the peak voltage of the rising ramp waveform and falls to a specific voltage level below the ground (GND) level voltage. By causing a weak erase discharge in the cells, the overcharged wall charge is sufficiently erased. By this set-down discharge, the wall charges such that the address discharge can be stably generated remain uniformly in the cells.

In the address period, the negative scan pulse Scan is sequentially applied to the Y electrodes, and the positive data pulse data is applied to the X electrode in synchronization with the scan pulse. As the voltage difference between the scan pulse and the data pulse and the wall voltage generated during the initialization period are added, an address discharge is generated in the cell to which the data pulse is applied. In the cells selected by the address discharge, wall charges such that discharge can occur when the sustain voltage Vs is applied are formed. The positive electrode voltage Vz is supplied to the Z electrode so that the voltage difference between the Y electrode is reduced during the set down period and the address period so that the discharge of the Y electrode does not occur.

In the sustain period, a sustain pulse Su is alternately applied to the Y electrode and the Z electrodes. In the cell selected by the address discharge, as the wall voltage and the sustain pulse in the cell are added, a sustain discharge, that is, a display discharge occurs between the Y electrode and the Z electrode every time the sustain pulse is applied.

After the sustain discharge is completed, a voltage of an erase ramp waveform (Ramp-ers) having a small pulse width and a low voltage level is supplied to the Z electrode to erase the wall charge remaining in the cells of the full screen.

The sustain driving waveform in the sustain section of the driving waveform according to the driving method of the conventional plasma display panel as described above in more detail as shown in FIG.

4 is a view for explaining in more detail the driving waveform in the sustain period of the driving waveform shown in FIG. As shown in the drawing, in the sustain driving waveform according to the driving method of the conventional plasma display panel, the sustain voltage Vs is alternately applied to the Y electrode and the Z electrode, and the ground (GND) voltage is applied to the X electrode. This sustain drive waveform is the same in all subfields. For example, a sustain voltage Vs is applied to the Y electrode, a ground (GND) level voltage is applied to the Z electrode, and a ground (GND) level voltage is applied to the Y electrode, and at the same time, the Z electrode is applied to the Y electrode. The sustain voltage Vs is applied. Here, the sustain voltage Vs means a voltage for maintaining the discharge of the cell. Accordingly, surface discharge occurs between the Y electrode and the Z electrode in the sustain period. When such a sustain driving waveform is applied, the shape of the discharge in the discharge cell will be described with reference to FIGS. 5A to 5B.

The discharge of the conventional plasma display panel occurs in a space surrounded by the X electrode formed on the lower substrate 110 and the Y electrode and Z electrode formed parallel to the upper substrate 100 so as to intersect the X electrode, that is, in the discharge cell. When the sustain voltage Vs is applied to the Y electrode while the ground level voltage is applied to the X electrode and the Z electrode in the first section, a discharge is generated by the Y electrode, where the positive (plus) potential is applied to the Y electrode. Since the sustain voltage Vs is applied, the negative charges in the discharge cell move toward the Y electrode. The movement of these negative charges is indicated by arrows in FIG. 5A. In addition, since the discharge occurs on the protective layer protecting the transparent electrode a and the bus electrode b, the protective layer is shown as an underline on the drawing.

When the sustain voltage Vs is applied to the Z electrode while the ground (GND) level voltage is applied to the X electrode and the Y electrode in the second section, a discharge by the Z electrode is generated, where the positive potential of the Z electrode is Since the sustain voltage Vs is applied, the negative charges in the discharge cell move toward the Z electrode. The movement of these negative charges is indicated by arrows in FIG. 5B.

The distribution of the wall charges in the discharge cells of the conventional plasma display panel having such a discharge type will be described with reference to FIGS. 6A to 6B.

6A to 6B are diagrams for explaining distribution of wall charges in a discharge cell according to a driving waveform in a conventional sustain period. 6A illustrates distribution of wall charges in on and off cells immediately after the end of a sustain period of one frame, that is, immediately after the end of the sustain discharge, in the discharge cells of the conventional plasma display panel. That is, immediately after the end of the sustain period of one frame, wall charges are accumulated above the critical point in the on-cell where the sustain discharge has occurred, and wall charges are accumulated below the critical point in the off-cell where the sustain discharge has not occurred. Therefore, for stable discharge in the next frame, wall charges accumulated in the on-cell and off-cell should be uniformly erased.

6B shows the distribution of the wall charges in the on-cell and off-cell after the reset discharge is generated in the reset section of the next frame immediately after the end of the sustain period of one frame. That is, immediately after the end of the sustain period of one frame, a ramp waveform is applied to uniformly erase the wall charges accumulated in the on-cell and off-cells, thereby reducing the wall charges accumulated in the on-cell and off-cells below the critical point.

However, even in this case, even if the wall charges accumulated in the on-cell and off-cells are less than or equal to the critical point, the degree of accumulation of wall charges is different, which adversely affects subsequent discharge characteristics. That is, in a discharge cell of a plasma display panel to which a conventional sustain waveform is applied, even if a reset waveform is applied to uniformly erase wall charges in the on-cell and off-cell immediately after the end of the sustain period of one frame, the reset waveform is applied in the on-cell and off-cell. Although the wall charges can be reduced below the critical point, it is difficult to overcome the difference in the distribution characteristics of the wall charges in the on-cell and off-cells, thereby inhibiting the discharge characteristics of the next frame, thereby resulting in a dark afterimage. That is, a dark afterimage is generated by the distribution distortion of the wall charges in the on-cell and off-cell. In addition, the longer the sustain period, the deeper the distribution distortion in the discharge cells of the wall charges, and more dark afterimages are generated.

In order to solve this problem, the present invention provides a method of driving a plasma display panel that can reduce the distortion of the distribution of wall charges between the on and off cells by improving the waveform applied to the sustain period. There is a purpose.

The driving method of the plasma display panel according to the present invention for achieving the above object is to display the image gradation of the plasma display panel having a scan electrode (Y electrode), a sustain electrode (Z electrode), and an address electrode (X electrode) by using a subfield. In the driving method described above, at least one of the subfields included in one frame is characterized in that a counter discharge occurs between the scan electrode and the address electrode in the sustain period.

The counter discharge is characterized in that the fifth discharge from the last surface discharge between the scan electrode and the sustain electrode in the sustain period.

The opposite discharge is generated in the last subfield of one frame.

The opposite discharge may be generated in a plurality of subfields in one frame.

The opposite discharge may be generated a plurality of times in accordance with the number of surface discharges in the sustain period of at least one subfield in one frame.

Hereinafter, a driving method of the plasma display panel of the present invention will be described in detail with reference to the accompanying drawings.

7 is a view showing a driving waveform for explaining a method of driving a plasma display panel according to a first embodiment of the present invention. Referring to FIG. 7, the driving waveform in one frame according to the plasma display panel driving method of the present invention is obtained from the last surface discharge between the Y electrode and the Z electrode in the sustain period of the last subfield among the subfields included in one frame. The counter discharge occurs between the Y electrode and the X electrode before any period in which the reset margin can be preserved. Any period in which this reset margin can be preserved is preferably before the fifth surface discharge from the last surface discharge in the sustain period. It is assumed that at least six surface discharges occur in the sustain period of the last subfield.

Here, while the sustain voltage Vs is alternately applied to the Y electrode and the Z electrode, a negative sustain voltage (-Vs) is applied to the Y electrode in the order in which the sustain voltage Vs is applied to the Y electrode. A voltage at the ground (GND) level is applied to the electrode, and a predetermined voltage is applied to the X electrode, which is greater than 0 V and smaller than the sustain voltage Vs, which may cause opposite discharge between the Y electrode and the X electrode. At this time, an opposite discharge occurs between the X electrode and the Y electrode. The driving waveform according to the driving method of the plasma display panel of the present invention is enlarged by enlarging the last subfield part in the driving waveform as shown in FIG. 8.

FIG. 8 is an enlarged view illustrating an enlarged portion of the last subfield in the driving waveform shown in FIG. 7. Referring to FIG. 8, the sustain voltage Vs is alternately applied to the Y electrode and the Z electrode so that a counter discharge occurs once between the X electrode and the Y electrode while the surface discharge occurs between the Y electrode and the Z electrode. The point at which the opposite discharge occurs is also at the end of the sustain period of the last subfield of one frame, i.e., at any time during which a reset margin can be preserved from the last surface discharge, for example, before the fifth surface discharge from the last surface discharge. This happens. Here, the reason why the opposite discharge occurs before the fifth from the last surface discharge is to prevent the sudden collapse of the reset margin in the reset section of the next subfield. That is, after the opposite discharge occurs between the Y electrode and the X electrode in the sustain period, the reset margin collapses rapidly in the next reset period unless the surface discharge between the Y electrode and the Z electrode does not occur at least five times until the next reset period. In this case, any period in which the reset margin can be preserved is set before the fifth surface discharge from the last surface discharge. However, any period in which the reset margin can be preserved can be adjusted according to the characteristics of the driving waveform or the sustain discharge. Can be.

The distribution of the wall charges in the discharge cells at the time when the opposite discharge between the Y electrode and the X electrode is generated according to the driving waveform of the present invention is as shown in Figs. 9a to 9c.

9A to 9C conceptually show wall charge distribution in discharge cells when the driving waveform shown in FIG. 8 is applied. As shown in FIG. 9A, the wall charge in the discharge cell is discharged, and the sustain voltage Vs is applied to the Y electrode and the ground (GND) level voltage is applied to the Z electrode. Surface discharge occurs between the electrode and the Z electrode. At this time, since a sustain voltage (Vs) is applied to the Y electrode, most of the negative charges move toward the Y electrode and are located near the Y electrode in the discharge cell. Since a voltage is applied, positive charges move in the direction of the Z electrode in response to negative charges located at the Y electrode, and are located near the Z electrode in the discharge cell.

Referring to FIG. 9B, a negative sustain voltage (-Vs) is applied to the Y electrode and a ground level voltage is applied to the Y electrode in the section (2) of FIG. 8, wherein the X electrode is greater than 0V and greater than the sustain voltage (Vs). A small voltage is applied to cause the opposite discharge between the X electrode and the Y electrode, and since a negative sustain voltage (-Vs) is applied to the Y electrode, most of the positive charges move toward the Y electrode and are located near the Y electrode in the discharge cell. Since a predetermined amount of voltage is applied to the X electrode, the negative charges in the discharge cell move in the X electrode direction and are located near the X electrode in the discharge cell.

Referring to FIG. 9C, negative charges are located near the Y electrode in the discharge cell, and positive charges are located near the Z electrode in the discharge cell in the third section shown in FIG. 8. It can be seen from the distribution of the wall charges that a strong sustain discharge is normally occurring in FIGS. 9A to 9C. In other words, the sustain discharge characteristic is maintained even when the opposite discharge between the Y electrode and the X electrode is inserted during the surface discharge between the Y electrode and the Z electrode in the sustain period.

In addition, when the surface discharge between the Y electrode and the Z electrode occurs in the sustain period, the opposite discharge between the Y electrode and the X electrode weakens the wall charge distribution characteristic that wall charges remain only on the Y electrode and the Z electrode. The reason is that when the surface discharge occurs only between the Y electrode and the Z electrode, when the opposite discharge occurs between the Y electrode and the X electrode, the wall charges located only at the Y electrode and the Z electrode move to the X electrode for a moment, so that the sustain period becomes longer. This is because the generated wall charges shake the phenomenon of remaining only in the Y electrode and the Z electrode.

The distribution of the wall charges in the discharge cells after applying a predetermined ramp waveform in the reset section in the next subfield after the counter discharge occurs in the sustain section is as shown in FIG. 10.

FIG. 10 is a view for explaining a distribution of wall charges in a discharge cell in a reset section of a next subfield after a driving waveform is applied in the method of driving a plasma display panel according to an exemplary embodiment of the present invention. Referring to FIG. 10, after applying a driving waveform according to the method of driving a plasma display panel of the present invention, the distribution of wall charges in a discharge cell after applying a predetermined ramp waveform in a reset section of a next subfield is It can be confirmed that the accumulation of wall charges in the on-cell and off-cell is the same within the error range below the wall charge threshold. In other words, the distribution distortion of wall charge between on-cell and off-cell is largely eliminated.

Accordingly, while maintaining the discharge characteristics in the sustain period, the wall charge distribution characteristic that the wall charges remain only on the Y electrode or the Z electrode may be weakened to uniform the distribution of the wall charges in the discharge cell. In addition, the distribution of the wall charges in the discharge cells is evened to stabilize the reset operation in the reset period of the first subfield of the next frame, thereby reducing the difference in the distribution characteristics of the wall charges between the on-cell and the off-cell, that is, reducing the wall charge distribution distortion. By reducing the formation of afterimages.

In the above, only the occurrence of the opposite discharge in the sustain period of the last sustain field of one frame is shown and described, but a predetermined number of surface discharges that can preserve the reset margin in the sustain period of the subfields included in one frame, For example, it is possible to achieve the object of the present invention by a driving waveform which causes a counter discharge in a subfield which generates six or more surface discharges. Looking at such a driving waveform as shown in FIG.

11 is a view for explaining a method of driving a plasma display panel according to a second embodiment of the present invention. Referring to FIG. 11, in the other driving waveform in one frame according to the driving method of the plasma display panel of the present invention, the surface discharge between the Y electrode and the Z electrode is 6 or more times in the sustain period among the subfields included in one frame. In the sustain periods of all the generated subfields, a counter discharge between the Y electrode and the X electrode is generated once. For example, assuming that a total of six subfields in which six surface discharges occur more than six times among subfields included in one frame, a counter discharge occurs once in each sustain period of the six subfields. In other words, the Y electrode and the X are once in the subfield having the number of discharges that can cause surface discharge between the Y electrode and the Z electrode more than 5 times after the counter discharge so as not to collapse the reset margin rapidly in the reset section of the next subfield. The opposite discharge between the electrodes occurs. If the sustain voltage Vs is applied seven times to the Y electrode and the alternating voltage is sequentially applied to the Z electrode, the sustain voltage Vs is applied to the Y electrode and the ground level voltage is applied to the Z electrode. After the surface discharge has occurred, a negative sustain voltage (-Vs) is applied to the Y electrode, a ground level voltage is applied to the Z electrode, and a predetermined voltage greater than 0 V and less than the sustain voltage (Vs) is applied to the X electrode. This causes opposite discharge between the Y electrode and the X electrode.

This driving waveform reduces the distortion of the distribution of wall charges between on-cell and off-cell at each reset when the sub-field is passed to the next subfield in the next reset period. Decreases.

Unlike this, a plurality of counter discharges are applied to a sustain period of a subfield having a discharge count that can generate a predetermined number of surface discharges, for example, six or more surface discharges, which can preserve a reset margin among subfields included in one frame. The afterimage can be reduced by the driving waveform that causes the driving waveform. The driving waveform is as follows.

12 is a view for explaining a method of driving a plasma display panel according to a third embodiment of the present invention. Referring to FIG. 12, another driving waveform in one frame according to the driving method of the plasma display panel of the present invention periodically generates a plurality of counter discharges in the sustain period of the last subfield of one frame. For example, in the sustain period of the last subfield, a counter discharge between the first Y electrode and the X electrode is caused, followed by a surface discharge between the Y electrode and the Z electrode five times, and then a second counter discharge between the Y electrode and the X electrode is again performed. In this way, the opposite discharge between the Y electrode and the X electrode is periodically generated. In FIG. 12, the total number of discharges of the last subfield is 16 for convenience of drawing. However, in the case of forming one frame with eight subfields, for example, 7 discharges of 2, that is, 128 discharges are generated. It is not difficult to make one discharge per synagogue.

Even in this case, the afterimage is reduced by the same principle as in FIG. 7 or 11.

In contrast, in the sustain periods of a plurality of subfields among subfields having a predetermined number of surface discharges, for example, six or more surface discharges that can generate a reset margin, among subfields included in one frame. The afterimage can be reduced by a driving waveform causing a plurality of opposing discharges. The driving waveform is as follows.

13 is a view for explaining a method of driving a plasma display panel according to a fourth embodiment of the present invention. Referring to FIG. 13, another driving waveform in one frame according to the driving method of the plasma display panel according to the present invention is a predetermined number of surface discharges, for example, 6, which can preserve a reset margin among subfields included in one frame. A plurality of opposing discharges are generated in the sustain section of the plurality of subfields among the subfields having the number of discharges capable of generating more than one surface discharge. For example, a plurality of opposite discharges are periodically generated in the sustain period of the last subfield, and less than the number of opposite discharges generated in the sustain period of the last subfield in the sustain period of the last subfield. In the sustain section of the previous subfield, a smaller number of counter discharges occur. That is, the number of counter discharges is adjusted according to the number of surface discharges in the sustain period.

This case also reduces the formation of dark spots for the same reason as in the case of FIG. 7 or 11 or 12 described above.

As such, the technical configuration of the present invention described above can be understood by those skilled in the art that the present invention can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, the exemplary embodiments described above are to be understood as illustrative and not restrictive in all respects, and the scope of the present invention is indicated by the appended claims rather than the foregoing detailed description, and the meaning and scope of the claims are as follows. And all changes or modifications derived from the equivalent concept should be interpreted as being included in the scope of the present invention.

As described in detail above, the present invention inserts a counter discharge into a sustain period of a subfield having a predetermined number of surface discharges capable of preserving a reset margin, for example, a discharge number capable of performing at least six surface discharges. By reducing the distribution distortion of the wall charge between on-cell and off-cell at the time of reset, there is an effect of reducing the generation of dark afterimages.

Claims (5)

A driving method for expressing image gradation of a plasma display panel having a scan electrode (Y electrode), a sustain electrode (Z electrode), and an address electrode (X electrode) by a subfield, At least one of the subfields included in one frame is a plasma display panel driving method, characterized in that the opposite discharge is generated between the scan electrode and the address electrode in the sustain period. The method of claim 1, And wherein the opposite discharge is fiveth before the last surface discharge between the scan electrode and the sustain electrode in the sustain period. The method of claim 1, And the opposite discharge is generated in the last subfield of one frame. The method of claim 1, And wherein the opposite discharge is generated in a plurality of subfields in one frame. The method of claim 4, wherein And wherein the opposite discharges are generated a plurality of times according to the number of surface discharges in the sustain period of at least one subfield in one frame.

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