KR20040036257A - Method for driving plasma display panel - Google Patents

Abstract

PURPOSE: A method for driving a plasma display panel is provided to perform a low-voltage driving operation, improve a darkroom contrast, and reduce an address period by lowering a peak voltage of a rising ramp waveform. CONSTITUTION: A sustain erase discharge process of a previous subfield is performed during a setup period of one or more subfield of plural subfields of one frame. A plurality of wall charges are generated during the setup period. The wall charges necessary for an address discharge are maintained by erasing partially the wall charges generated by the setup period during a set down period. During the setup period, a positive voltage is applied to a scan electrode and a rising ramp waveform is provided to a sustain electrode. During the set down period, a falling ramp waveform is applied to the scan electrode and the positive voltage is provided to the sustain electrode.

Description

Driving Method of Plasma Display Panel {METHOD FOR DRIVING PLASMA DISPLAY PANEL}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a plasma display panel, and more particularly, to a method for driving a plasma display panel that can improve darkroom contrast and shorten an address period.

Plasma Display Panel (hereinafter referred to as "PDP") displays an image including text or graphics by emitting phosphors by 147 nm ultraviolet rays generated during discharge of He + Xe or Ne + Xe inert mixed gas. . 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 13Y, 13Z).

The transparent electrodes 12Y and 12Y 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 a stripe or lattice shape to prevent the ultraviolet rays and the 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 an initialization 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 levels according to the number of discharges.

Here, the initialization 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. As described above, each of the eight subfields SF1 to SF8 is divided into an initialization period, an address period, and a sustain period. The initialization 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 driven by being divided into an initialization 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 initialization period, the rising ramp waveform Ramp-up is simultaneously applied to all the scan electrodes Y up to the peak voltage Vp. This rising ramp waveform (Ramp-up) causes a slight discharge in the cells of the full screen to generate wall charges in the cells. During the set down period, after the rising ramp waveform Ramp-up is supplied, the falling ramp waveform Ramp-down falling at the positive voltage lower than the peak voltage of the rising ramp waveform Ramp-up 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, a negative scan pulse scan is sequentially applied to the scan electrodes Y and a 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 in the initialization 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 electrode 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 each time 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.

In the reset period of the conventional PDP driven as described above, the wall charge necessary for the address discharge must be uniformly retained. In addition, since the address discharge is easily generated when the negative wall charges (approximately intermediate voltages between the scan electrode Y and the address electrode X) remain on the sustain electrode Z experimentally, the sustain electrode Z is easily generated. Negative wall charges must remain. However, in the driving waveform of the conventional PDP shown in FIG. 3, sufficient negative wall charges do not remain in the sustain electrode Z since the ramp ramp down to the ground potential GND.

In order to solve this problem, a method of lowering the ramp ramp down to the negative voltage (-Vr) as shown in FIG. 4 has been proposed. When the ramp ramp down is lowered to the negative voltage (-Vr), sufficient erasing is performed in the discharge cell, thereby easily generating an address discharge. That is, sufficient negative wall charges can remain in the sustain electrode Z.

However, in the conventional method of supplying the driving waveform, a large number of fine discharges are generated when the ramp-up supply is applied, and the dark-room contrast ratio is reduced by the fine discharge. have. In detail, when the rising ramp waveform Ramp-up is supplied, surface discharge occurs between the scan electrode Y and the sustain electrode Z, and a counter discharge occurs between the scan electrode Y and the address electrode X in the discharge cells. do. Most of the light generated in the surface discharge between the scanning electrode (Y) and the sustain electrode (Z) is emitted to the observer located in the front of the screen, so there is a problem that the darkroom contrast ratio is lowered.

Accordingly, it is an object of the present invention to provide a method of driving a plasma display panel which can improve darkroom contrast and shorten an address period.

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

2 illustrates a frame of a plasma display panel divided into a plurality of subfields.

3 is a waveform diagram showing a driving method of a conventional plasma display panel.

4 is a waveform diagram illustrating a method of driving a plasma display panel according to another conventional embodiment.

5 is a waveform diagram illustrating a method of driving a plasma display panel according to an embodiment of the present invention.

6 is a diagram illustrating a reset current flowing in a panel to which a driving method according to an embodiment of the present invention is applied.

7 is a diagram illustrating an address current flowing in a panel to which a driving method according to an embodiment of the present invention is applied.

8 is a diagram showing an address current flowing when a driving method according to an embodiment of the present invention is applied to a high density Xe panel.

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

<Description of Symbols for Main Parts of Drawings>

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

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

16: protective film 18: lower substrate

24: partition 26: phosphor layer

In order to achieve the above object, the driving method of the plasma display panel according to the present invention eliminates the sustain discharge of the previous subfield and forms wall charges at the same time during the setup period of at least one or more of the plurality of subfields included in one frame. And erasing a part of the wall charges formed by the setup discharge in the set-down period after the setup period so as to uniformly retain the wall charges required for the address discharge.

Supplying a positive voltage to the scan electrode during the setup period, and supplying a rising ramp waveform to the sustain electrode during the setup period.

And supplying a falling ramp waveform to the scan electrode during the set down period, and supplying a positive voltage to the sustain electrode during the set down period.

After the sustain period, an erase pulse for erasing the sustain discharge is not supplied.

A method of driving a plasma display panel according to the present invention includes supplying a rising ramp waveform to a sustain electrode during the set-up period of at least one or more of the subfields included in one frame, and at least one or more of the plurality of subfields. And supplying a first positive voltage to the scan electrode during the setup period of the subfield.

The rising ramp waveform supplied to the sustain electrode is supplied after the second voltage value is higher than or equal to the voltage value of the first voltage.

The voltage value of the second voltage is set lower than twice the voltage value of the first voltage.

The subfield includes an address period for selecting a cell and a sustain period for causing discharge in the selected cell, and no erase pulse is supplied after the sustain period.

Supplying a second voltage having the same voltage value as the first voltage to the sustain electrode at the beginning of the setup period, maintaining the second voltage for a predetermined time, and maintaining the sustain voltage after the second voltage is maintained for a predetermined time. And applying a voltage value obtained by adding the second voltage to the third voltage.

The voltage value of the third voltage is set smaller than the voltage value of the first voltage.

The first voltage applied to the scan electrode is applied when a voltage value obtained by combining the second voltage and the third voltage is applied to the sustain electrode.

The rising ramp waveform supplied to the sustain electrode is supplied with a slope from a voltage value in which the second voltage and the third voltage are combined.

The constant time is determined between 1 ms and 5 ms.

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. 5 to 9.

5 is a waveform diagram showing a driving waveform according to an embodiment of the present invention.

5 is a waveform diagram showing a driving waveform supplied to the n (n is a natural number) th subfield. The driving waveform according to the embodiment of the present invention has the same set down period, address period and sustain period as those of the conventional driving waveform shown in FIG.

Referring to FIG. 5, the driving waveform of the PDP of the present invention is driven by being divided into an initialization period for initializing the full screen, an address period for selecting a cell, and a sustain period for maintaining discharge of the selected cell. Here, the erase pulse is not supplied to the sustain electrode Z after the sustain period. In other words, as shown in FIG. 5, the erase pulse is not supplied after the sustain period of the n-1 subfield.

In the initialization period, the first voltage V1 is supplied to the scan electrodes Y during the setup period. In addition, the rising ramp waveform Ramp-up rising from the second voltage V2 is supplied to the sustain electrodes Z during the setup period. When the rising ramp waveform Ramp-up is supplied to the sustain electrodes Z, a plurality of fine discharges occur during the setup period. This microdischarge eliminates the sustain discharge of the previous subfield and forms wall charges in the cells. On the other hand, the voltage value of the second voltage (V2) is set higher than or equal to the voltage value of the first voltage (V1). Here, the voltage value of the second voltage V2 is set smaller than the voltage value twice that of the first voltage V1 so that no strong surface discharge occurs between the scan electrodes Y and the sustain electrodes Z. FIG.

In detail, the setup period is first supplied with the last sustain pulse in the previous subfield to the scan electrode (Y). Therefore, negative wall charges are formed on the scan electrode Y and positive wall charges are formed on the sustain electrode Z at the start of the setup period. Subsequently, when the rising ramp waveform Ramp-up rising from the second voltage V2 is supplied to the sustain electrode Z, the positive polarity accumulated in the previous subfield is applied to the voltage value of the wall charge and the rising ramp waveform Ramp-up. The voltage values of are added together. Therefore, a plurality of fine discharges are generated in the discharge cells. Such microdischarge eliminates the sustain discharge of the previous subfield and forms wall charges in the cells.

On the other hand, in the present invention, the peak voltage Vp1 of the rising ramp waveform Ramp-up is set lower than the conventional peak voltage Vp1 shown in FIG. 4 (several to several hundred volts lower). That is, in the present invention, since the wall charges are formed in the cells through the erase discharge, a lower peak voltage Vp1 can be applied. Therefore, in the present invention, since the voltage value of the peak voltage Vp1 is lower than that of the conventional peak voltage Vp, the number of surface discharges between the scan electrode Y and the sustain electrode Z is reduced, thereby darkroom contrast. Can improve. For example, when the rising ramp waveform Ramp-up having the peak voltage 420V lower than that of the conventional PDP 480V is applied as shown in FIG. 6, a weak current flows during the initialization period. Weak surface discharge occurs during this period.)

On the other hand, in the present invention, since the positive ramp ramp Ramp-up is applied to the sustain electrode Z, sufficient negative wall charge necessary for the address discharge can be ensured. Therefore, it is possible to cause the address discharge to be stable (in a quick time) during the address period. For example, in the present invention, as shown in FIG. 7, the address discharge delay can be reduced by about 10% compared to the conventional PDP.

On the other hand, the PDP proposed through Japanese Patent Application Laid-Open No. 2001-135238 increases the density of Xe components in the discharge gas encapsulated in the PDP, so that the driving voltage is higher than that of the conventional low density Xe panel. Higher, but higher brightness. Applying the present invention to such a high density Xe panel, it is possible to lower the driving voltage of the high voltage level required by increasing the Xe component in the discharge gas (the peak voltage value (Vp1) is lowered) is applied to a high density Xe panel and high brightness Low voltage driving can be satisfied at the same time.

For example, when the present invention is applied to a high-density Xe panel as shown in FIG. That is, the wall charges can be stably formed during the initialization period in which the low driving voltage is supplied, and thus stable address discharge can be caused even in the address period of the high density Xe panel. (In simulation, the Xe density of FIG. 7 was set to 8% and the Xe density of FIG. 8 was set to 14%)

Meanwhile, in the n subfield of the present invention, the initial discharge is generated by using the wall charges formed in the previous sustain discharge. Therefore, the driving waveform supplied in the first subfield located at the first of the frame can be set in the same manner as the conventional driving waveform shown in FIG.

In the set down period, a falling ramp waveform Ramp-down falling from the first voltage V1 to the negative voltage −Vr is simultaneously applied to the scan electrodes Y. 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, a negative scan pulse scan is sequentially applied to the scan electrodes Y and a 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 in the initialization 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.

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 each time the sustain pulse sus is applied while the wall voltage and the sustain pulse sus in the cell are added. Discharge occurs.

9 is a waveform diagram illustrating a driving waveform according to another embodiment of the present invention.

9 is a waveform diagram showing a driving waveform supplied to the nth subfield. Such a driving waveform according to another embodiment of the present invention has the same set down period, address period and sustain period as those of the driving waveform according to the embodiment of the present invention shown in FIG.

Referring to FIG. 9, the driving method of the PDP of the present invention is driven by dividing into an initialization period for initializing the full screen, an address period for selecting a cell, and a sustain period for maintaining discharge of the selected cell. Here, the erase pulse is not supplied to the sustain electrode Z after the sustain period. In other words, as shown in Fig. 9, the erase pulse is not supplied after the sustain period of the n-1 subfield.

In the initialization period, the second voltage V2 is supplied to the sustain electrodes Z during the setup period. After the second voltage V2 is supplied to the sustain electrodes Z, the second voltage V2 is maintained for a predetermined time T1 and then the voltage values of the second voltage V2 and the third voltage V3 are decreased. The added voltage is applied. That is, voltage values of the second voltage V2 and the third voltage V3 are supplied to the sustain electrodes Z. After the voltage values of the second voltage V2 + third voltage V3 are supplied to the sustain electrodes Z, the rising ramp waveform rising to the peak voltage Vp1 with a low slope to the sustain electrodes Z is performed. Ramp-up is supplied.

After the start of the setup period, the scan electrodes Y are supplied with the voltage value of the first voltage V1 after the predetermined time T1. Here, the reason why the voltage value of the first voltage V1 is supplied to the scan electrodes Y after the predetermined time T1 is that the value of the first voltage V1 supplied to the scan electrodes Y is the sustain electrodes. This is to prevent the voltage from being applied before the voltage value of the second voltage V2 supplied to (Z). Therefore, the predetermined time T1 may be determined between a short time, for example, 1 ms to 5 ms. On the other hand, the voltage value of the first voltage V1 and the voltage value of the second voltage V2 are set equal. In addition, the voltage value of the third voltage V3 is set lower than the voltage of the first voltage V1 to prevent strong discharge from occurring between the scan electrodes Y and the sustain electrodes Z. FIG.

On the other hand, when the rising ramp waveform Ramp-up is supplied to the sustain electrodes Z during the setup period, a plurality of fine discharges occur during the setup period. This microdischarge eliminates the sustain discharge of the previous subfield and forms wall charges in the cells.

In detail, the setup period is first supplied with the last sustain pulse in the previous subfield to the scan electrode (Y). Therefore, negative wall charges are formed on the scan electrode Y and positive wall charges are formed on the sustain electrode Z at the start of the setup period. Subsequently, when the rising ramp waveform Ramp-up rising from the second voltage V2 + the third voltage V3 is supplied to the sustain electrode Z, the positive polarity accumulated in the previous subfield increases with the voltage value of the wall charge. The ramp-up voltage values are added together. Therefore, a plurality of fine discharges are generated in the discharge cells. Such microdischarge eliminates the sustain discharge of the previous subfield and forms wall charges in the cells.

Further, in another embodiment of the present invention, the peak voltage Vp1 of the rising ramp waveform Ramp-up is set equal to the peak voltage Vp1 according to the embodiment of the present invention shown in FIG. Therefore, in another embodiment of the present invention, the number of surface discharges between the scan electrode Y and the sustain electrode Z is reduced as compared with the conventional PDP, thereby improving darkroom contrast.

In addition, in another embodiment of the present invention, as described in the embodiment of the present invention illustrated in FIG. 5, the address discharge delay may be reduced by about 10% compared to the conventional PDP. In addition, since the rising ramp waveform (Ramp-up) having a lower peak voltage (Vp1) than the conventional one is supplied, it can be applied to the high-density Xe panel to satisfy high brightness and low voltage driving at the same time.

Meanwhile, in the n subfield according to another embodiment of the present invention, the initial discharge is generated by using the wall charges formed in the previous sustain discharge. Therefore, the driving waveform supplied in the first subfield located at the first of the frame can be set in the same manner as the conventional driving waveform shown in FIG.

In the set down period, a falling ramp waveform Ramp-down falling from the first voltage V1 to the negative voltage −Vr is simultaneously applied to the scan electrodes Y. 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, a negative scan pulse scan is sequentially applied to the scan electrodes Y and a 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 in the initialization 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.

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 each time the sustain pulse sus is applied while the wall voltage and the sustain pulse sus in the cell are added. Discharge occurs.

As described above, according to the driving method of the plasma display panel according to the present invention, the rising ramp waveform is supplied to the sustain electrode during the setup period, thereby erasing the sustain discharge of the previous subfield and simultaneously forming wall charges in the cells. Therefore, the peak voltage of the rising ramp waveform can be lowered compared to the conventional PDP, thereby enabling low voltage driving. (So, it is easy to apply a high density Xe panel.) In addition, the number of fine discharges generated during the initialization period By reducing the darkroom contrast can be improved. In addition, the address discharge delay can be reduced to enable a high speed address.

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 (13)

In a driving method of a plasma display panel including a setup period, a setdown period, an address period and a sustain period, During the set-up period of at least one of the plurality of subfields included in one frame, erasing the sustain discharge of the previous subfield and simultaneously forming wall charges; And erasing a part of the wall charges formed by the setup discharge in the setdown period after the setup period to uniformly retain the wall charges required for the address discharge. The method of claim 1, Supplying a positive voltage to a scan electrode during the setup period; And supplying a rising ramp waveform to the sustain electrode during the set-up period. The method of claim 1, Supplying a falling ramp waveform to the scan electrode during the set down period; And supplying a positive voltage to the sustain electrode during the set down period. The method of claim 1, And an erase pulse for erasing the sustain discharge is not supplied after the sustain period. In a driving method of a plasma display panel having a plurality of scan electrodes and sustain electrodes formed in parallel to each other and comprising a setup period and a setdown period for uniformly forming wall charges in the cells, Supplying a rising ramp waveform to the sustain electrode during the setup period of at least one or more of the plurality of subfields included in one frame; And supplying a first positive voltage to the scan electrode during the setup period of at least one of the plurality of subfields. The method of claim 5, The rising ramp waveform supplied to the sustain electrode is supplied after a second voltage value higher than or equal to the voltage value of the first voltage is supplied. The method of claim 6, And the voltage value of the second voltage is set lower than twice the voltage value of the first voltage. The method of claim 5, And the subfield includes an address period for selecting a cell and a sustain period for causing discharge in the selected cell, wherein an erase pulse is not supplied after the sustain period. The method of claim 5, Supplying a second voltage having the same voltage value as the first voltage to the sustain electrode at the beginning of the setup period; Maintaining the second voltage for a predetermined time; And applying a voltage value obtained by adding the second voltage and the third voltage to the sustain electrode after the second voltage is maintained for a predetermined time. The method of claim 9, And the voltage value of the third voltage is set smaller than the voltage value of the first voltage. The method of claim 9, And a first voltage applied to the scan electrode is applied when a voltage value obtained by combining the second voltage and the third voltage is applied to the sustain electrode. The method of claim 9, The rising ramp waveform supplied to the sustain electrode is supplied with a slope from a voltage value in which the second voltage and the third voltage are combined. The method of claim 9, And said predetermined time is determined between 1 ms and 5 ms.