KR20000001515A - Method of driving a plasma display panel - Google Patents

Abstract

PURPOSE: A driving method of a plasma display panel is provided to safely display an image above a display panel by preventing a discharge irregularity in sub frame driving fashion. CONSTITUTION: The PDP driving method comprises the step of: driving separately in a writing period wherein a wall charge is generated, an erase period wherein an unessential charge is erased and then a dynamic charge remains, an addressing period wherein video data is displayed, and a sustain period wherein a discharge is maintained. Thereby, in a case of driving sub-frame fashion, uniform wall charges is generated above a display panel by performing writing before erasing at each sub-frame, and thus next addressing voltage is lowered and a high speed discharge is performed.

Description

Method of Driving Plasma Display Panel

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel (PDP), which is one of flat panel display devices. In particular, the present invention relates to a PDP capable of displaying a stable image on a full screen by preventing unevenness of discharge. It relates to a driving method of.

In general, a PDP is a display device that displays an image by using a gas discharge phenomenon. The PDP obtains a discharge through voltage control applied between vertical and horizontal electrodes of a cell constituting a pixel, and the amount of light discharged is within the cell. Adjust by varying the length of discharge time. The full screen includes write pulses for inputting digital image signals to the vertical and horizontal electrodes of each cell, scan pulses for scanning, sustain pulses for sustaining discharge, and discharged cells. An erase pulse for stopping the discharge is applied to drive the matrix. Here, the step brightness required for image display, that is, gray scale, is that each cell discharges within a given time (e.g., 16.67 ms for an NTSC TV signal) to display an image of one frame representing a screen. This is done by varying the length of time it takes. At this time, the brightness of the screen is determined by the brightness when each cell is driven to the maximum. In order to increase the brightness, the driving circuit is designed to keep the discharge time of the cell as long as possible within a given time in one frame. Should be. Contrast, which represents the difference in contrast, is determined by the brightness and brightness of the background, such as lighting. In order to increase this contrast, not only the background needs to be darkened, but also the brightness needs to be increased.

For example, in the case of a flat panel display device for HDTV, 256 gray levels are required, the resolution should be 1280 × 1024 or more, and the contrast under 200 lux lighting requires 100: 1 or more. Therefore, in order to display a 256 gray level image, the image digital signal requires 8 bits (Bit) of the color signals R, G, and B, respectively, and the discharge time of the cell is extended as long as possible to obtain the required luminance and contrast. It must be maintained. PDP driving methods for gray scale implementation include a sub-field driving method and a sub-frame driving method.

Referring to FIG. 1, a structure of a PDP cell of a three-electrode surface discharge alternating current (AC) type which is commonly used is shown.

The cell of the PDP shown in FIG. 1 includes an upper substrate 10 which is a display surface of an image, and a lower substrate 20 arranged in parallel with the upper substrate 10 by a partition wall 26. The partition wall 26 isolates between the cells to provide a discharge space inside the cell. On the upper substrate 10, two sustain electrodes, that is, a scan and sustain electrode (hereinafter referred to as Y sustain electrode) 12 and a sustain electrode (hereinafter referred to as Z sustain electrode) 14 are arranged side by side. . The Y and Z sustain electrodes 12, 14 are transparent electrodes (ITO) 12a, 14a for transmitting light, and bus electrodes 12b, 14b for improving the conductivity of the transparent electrodes 12a, 14a. It consists of. On the lower substrate 20, Y and Z sustain electrodes 12 and 14 and an address electrode 22 for causing discharge are disposed. To the Y and Z sustain electrodes 12 and 14 and the address electrode 22, an alternating current (AC) voltage whose polarity is continuously reversed is applied to maintain the discharge.

On the upper substrate 10 on which the Y and Z sustain electrodes 12 and 14 are disposed, an upper dielectric layer 16 for charge accumulation is formed flat, and a protective film 18 is formed on the upper dielectric layer 16 surface. Formed. The protective film 18 protects the upper dielectric layer 16 from sputtering of plasma particles to extend its lifespan, improve the emission efficiency of secondary electrons, and reduce the change of discharge characteristics due to oxide contamination of the refractory metal. By doing so, a magnesium oxide (MgO) film is mainly used. The lower dielectric layer 24 for charge accumulation is also formed flat on the lower substrate 20 on which the address electrode 22 is disposed, and the visible rays R, G, and B of intrinsic color are generated on the lower dielectric layer 24. Phosphor layer 30 is applied so as to capture partition 26. The phosphor layer 30 is excited by a short wavelength of ultraviolet (VUV) generated during gas discharge to generate visible light of red, green, and blue (R, G, B). The black matrix 28 formed on the top of the partition wall 26 serves to prevent the lowering of the contrast caused by the reflection of external light. The discharge space provided inside the cell is mainly filled with a mixed gas of argon (Ar) and xenon (Xe) in order to increase ultraviolet emission efficiency.

FIG. 2 is a diagram illustrating an arrangement of electrodes of a PDP, wherein the PDP of FIG. 2 has Y and Z arranged in a matrix structure in a region 34 in which an upper substrate 10 and a lower substrate 20 are opposed to each other. Sustain electrode lines Y and Z and address electrode lines X are provided.

In the PDP of FIG. 2, the Y sustain electrode lines Y1 to Ym and the Z sustain electrode lines Z1 to Zm are arranged to be alternated in the horizontal direction, and the pair of sustain electrode lines Y and Z are arranged in one row ( Row). The address electrode lines X1 to Xn are arranged in a vertical direction to intersect the pair of sustain electrode lines Y and Z, and cells 32 as shown in FIG. 1 are formed at the intersections thereof. Here, the pair of sustain electrode lines Y and Z forming a row are mainly used to scan a screen and to maintain a discharge, and the address electrode lines X forming a column are mainly used for data input.

In detail, a sustain pulse for maintaining the discharge of the cell and an erase pulse for stopping the discharge of the discharged cell are applied to the Z sustain electrode line Z, and the discharge is maintained for the Y sustain electrode line Y. The sustain pulse to cancel the discharge of the discharged cells and the scan pulse synchronized with the video data signal applied to the address electrode line X are applied. Data pulses are input to the address electrode line X. The data pulses cause a write discharge in response to a scan pulse applied to the Y sustain electrode line Y.

Referring to FIG. 3, when the PDP of FIG. 2 is driven by a subframe driving method, a voltage pulse supplied to the Y and Z sustain electrode line pairs Y and Z and the address electrode line X during the first subframe is illustrated. have. In FIG. 3, (a) shows voltage pulses supplied to the address electrode lines X, (b) and (c) show voltage pulses supplied to each of the first sustain electrode line pairs Y1 and Z1, d) and (e) show voltage pulses supplied to each of the nth sustain electrode line pair (Yn, Zn).

When the cell is to be discharged, when a data pulse having a positive voltage Vaw value is input to the address electrode line X and a scanning pulse synchronized with the data pulse is input to the Y sustain electrode lines Y1 and Yn, The voltage between the address electrode line X and the Y sustain electrode lines Y1 and Yn becomes higher than or equal to the threshold voltage necessary for causing the discharge, so that discharge occurs sequentially. This state is applied to the electric field generated by the electric field generated by the charged particles charged to the insulating film by discharge and the sustain pulse applied to the Y sustain electrode lines (Y1, Yn) and the Z sustain electrode lines (Z1, Zn) opposite to each other. Is maintained until another erase pulse is applied. Then, when an erase pulse Vs having a lower amplitude than the scan pulse is applied to the Y sustain electrode lines Y1 and Yn and the Z sustain electrode lines Z1 and Zn, the sum of the electric field by the charged particles and the electric field by the erasing pulse is applied. Insufficient small discharge occurs to sustain this discharge, and the discharge disappears when the next sustain pulse is applied. Summarizing the roles of the above-described electrode lines, the Y sustain electrode line Y serves as sustain, screen scanning and erasing, and the Z sustain electrode line Z performs the sustain function and erase discharge, and the address electrode ( X) is responsible for data input for screen composition.

FIG. 4 is a cross-sectional view illustrating a discharge phenomenon generated in one cell by a driving waveform as shown in FIG.

First, when an erase voltage (Vs) pulse is applied to the Y sustain electrode 12 and no voltage is applied to the Z sustain electrode 14 and the address electrode 22, it becomes below a threshold voltage for causing discharge. As shown, no discharge occurs in the discharge cell. Subsequently, when a data pulse, i.e., a positive voltage Vaw pulse is applied to the address electrode 22 and a sufficient voltage Vyw pulse is applied to the Y sustain electrode 12, a discharge occurs in the cell. As shown in (b), wall charges are formed. At this time, the voltage Vyw of the Y sustain electrode 12 should be a level that does not cause sustain discharge even when a sustain discharge pulse is applied to the Y and Z sustain electrodes 12 and 14, and the voltage Vaw to the address electrode 22. When the Y and Z sustain electrodes 12 and 14 sustain discharge pulses are applied only when they are applied, a sustain discharge is caused. Subsequently, as shown in (c) and (d), the sustain discharge period generated by alternately applying sustain voltage (Vs) pulses to the Y and Z sustain electrodes 12 and 14 ends, and in the next subframe, (a) Erase discharge is performed again as shown in FIG. The sub frame driving method displays a screen of one frame.

However, the above-described conventional PDP driving method must not only apply a very high scan voltage Vyw to the Y sustain electrode in order to generate wall charges uniformly on the full screen, but also make the pulse width very wide. In other words, the larger the difference between the write voltage for generating wall charge and the sustain voltage for sustaining discharge, the full screen can be displayed with uniform brightness. Although the voltage is high, there is a problem in that the difference with the sustain voltage Vs is small so that wall charges cannot be generated uniformly. In addition, there is a problem that the pulse width of the scan voltage is wide, which is very disadvantageous for high speed driving.

Accordingly, it is an object of the present invention to provide a PDP driving method capable of displaying a stable image on the full screen by eliminating discharge unevenness in the subframe driving method.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view showing the structure of a PDP pixel cell of a conventional AC system.

2 is an electrode arrangement diagram of a PDP.

3 is a view showing a waveform supplied to each electrode line of FIG. 2 according to a conventional driving method.

4 is a cross-sectional view illustrating a discharge phenomenon generated inside a cell by a driving waveform as shown in FIG.

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

FIG. 6 is a cross-sectional view illustrating the discharge phenomenon generated in the inside of one cell by the driving waveform as shown in FIG.

7 is a diagram illustrating a driving sequence of a subframe method and arrangement of subframes.

<Brief description of symbols for the main parts of the drawings>

10: upper substrate 12: Y sustain electrode

14 Z sustain electrode 16 upper dielectric

18: protective film 20: lower substrate

22: address electrode 24: lower dielectric

26: bulkhead 28: black matrix

30 phosphor 32 cell

In order to achieve the above object, the PDP driving method according to the present invention includes a plurality of frames when displaying digital video signals in a three-electrode alternating current plasma display panel in which each cell is composed of two sustain electrodes and one address electrode. In each subframe driving method in which one or more address electrodes discharge sustaining discharge when one or more address electrodes are addressed and discharged, the writing period for generating wall charges and unnecessary charges are eliminated and only substationary charges are eliminated. And an erasing section for remaining, an addressing section for displaying video data, and a sustain section for maintaining discharge.

Other objects and advantages of the present invention in addition to the above object will become apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.

FIG. 5 illustrates driving waveforms according to the PDP driving method according to the present invention. When the PDP is driven by a subframe driving method, a pair of Y and Z sustain electrode lines (Y and Z) and an address electrode line (Y) during the first subframe are shown. The pulse waveform supplied to X) is shown. In FIG. 5, (a) shows the pulse waveform supplied to the address electrode line X, (b) and (c) shows the pulse waveform supplied to each of the first sustain electrode line pair Y1 and Z1, d) and (e) show pulse waveforms supplied to each of the nth sustain electrode line pairs Yn and Zn. In addition, by changing the supply voltage applied to the Y and Z sustain electrode lines (Y, Z) in three steps, the effect of energy recovery can be obtained.

In the present invention, the conventional erasing section is composed of a writing section and an erasing section. In other words, the present invention includes a writing section for uniformly generating wall charges in all cells before the erasing section. First, writing discharge is generated by simultaneously applying writing voltage pulses to the Y sustain electrode lines Y1 and Yn to be driven and the Z sustain electrode lines Z1 and Zn to generate wall charges uniformly across the entire surface. In other words, a ground voltage (0 V) pulse is applied to the Y sustain electrode lines Y1 and Yn, and a high voltage Vzw pulse is applied to the Z sustain electrode lines Z1 and Zn to discharge the lighting discharge. Subsequently, low erase voltage pulses are applied to the Y sustain electrode lines Y1 and Yn and the Z sustain electrode lines Z1 and Zn to cause microdischarge, that is, erasing discharge, thereby eliminating unnecessary charges, and leaving only the wall charge for the next addressing discharge. Release. At this time, a common voltage (Vs) pulse is applied to the Y sustain electrode lines (Y1, Yn), and a ground voltage (0V) pulse is applied to the Z sustain electrode lines (Z1, Zn) to cause microdischarge. Here, the residual wall charges due to the erase discharge should be at a level that does not cause discharge due to the sustain voltage. Next, a data pulse having a positive voltage Vaw value is applied to the address electrode line X, and an addressing scan pulse synchronized with the data pulse is applied to the Y sustain electrode lines Y1 and Yn to sequentially address the address. Discharges cause wall charges that can cause sustain discharge in the cell. At this time, in the addressing discharge period, the residual wall charge is added to cause the discharge even at a low addressing voltage Vyw. Subsequently, the writing pulses of the other subframes are generated by the wall charges formed by the addressing discharge and the electric field generated by the sustain pulses applied to the Y sustain electrode lines Y1 and Yn and the Z sustain electrode lines Z1 and Zn opposite to each other. It is maintained until it is applied.

6 illustrates a discharge phenomenon in a cell by the PDP driving method according to the present invention.

As shown in FIG. 6A, when the voltage Vzw is applied to the Z sustain electrode and the base voltage (0 V) is applied to the Y sustain electrode and the address electrode, initial discharge occurs. Then, as shown in (b), when the erase voltage Ve (for example, Vs) is applied to the Y sustain electrode and the base voltage (0 V) is applied to the Z sustain electrode, only the undesired erase and wall charge remain. This residual wall charge is used in addition to the voltage applied between the Y sustain electrode and the address electrode at the time of address discharge as shown in (c), so that the discharge can be performed at a much lower voltage than the previous discharge, and the pulse width is short. It is also advantageous in high speed driving. Also. It can cause a uniform discharge on the full screen, which increases the memory margin and improves image quality. As shown in (d), the sustain pulses applied to the Y sustain electrode and the Z sustain electrode are added to the wall charges generated by the addressing discharge to cause the sustain discharge to display an image.

7 shows the driving order of the subframe method in time for one frame. In the subframe driving method illustrated in FIG. 7A, when the plurality of address electrodes discharge address, the other address electrodes sustain sustain discharge. In other words, a plurality of scanning lines are selected for each subframe to cause addressing discharges in line order, and then sustain discharges in line order. In the subframe driving method, as shown in (b), one subframe is conventionally composed of an erasing section, a write-address section, and a sustain section. However, in the present invention, as shown in (c), a writing section, an erasing section, It consists of an addressing section and a sustain section.

Here, the next addressing voltage may be generated even in the first subframe per frame without generating the writing period, that is, the lighting discharge for each subframe, or in the n subframes per frame. Can be lowered.

As described above, according to the PDP driving method according to the present invention, in the case of driving in a subframe method, a writing section is arranged before the erasing section in each subframe to form uniform wall charges on the full screen, and unnecessary wall charges due to micro discharges. By eliminating, not only the following addressing voltage can be lowered, but also the pulse width can be shortened to cause high-speed discharge. In addition, by using the residual wall charges uniformly formed on the full screen, a uniform discharge can be generated on the full screen, thereby increasing the memory margin and improving image quality.

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 (4)

When a digital image signal is displayed on a three-electrode plasma display panel having two sustain electrodes and one address electrode, the cells are divided into a plurality of subframes and one or more address electrodes are used for addressing discharge. In the method of driving each sub-frame when the other address electrodes sustain sustain discharge, A lighting section for generating wall charges, An erasing section for eliminating unnecessary charges and leaving only substation charges; An addressing section for displaying video data, A plasma display panel driving method comprising a sustain section for maintaining a discharge. The method of claim 1, And the writing period is included only in a first subframe of the plurality of subframes. The method of claim 1, And the writing period is included only in n subframes of the plurality of subframes. The method of claim 1, And a lighting discharge is generated by applying a voltage between the two sustain electrodes in the lighting section.