KR20000051479A - Driving method for Plasma Display Panel - Google Patents

Abstract

PURPOSE: A method of driving plasma display panel(PDP) is provided to achieve an improved contrast and to reduce a flicker of screen by applying both a line scanning system and a subfield system. CONSTITUTION: A method of driving PDP which implements each pixel having 8bit grey data onto a screen comprises the steps of: embodying the contrast data of m bits from among the 8bit contrast data by a subfield system; embodying the contrast data of (8-m) bits excluding the contrast data embodied by a subfied system by a line erase scanning system. Following a FIG 5, M is larger than 1 and smaller than 8. The step of embodying this system by the subfield system is for higher bit contrast data while the step of embodying this system by the line scanning system is for lower bit contrast data. Such a mixed application of line scanning system and subfield system achieve a reduced frequency of write discharge.

Description

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

The present invention relates to a method for driving a plasma display panel (hereinafter referred to as a plasma display panel), and more particularly to an algorithm for driving PD.

Plasma display panels and liquid crystal displays (LCDs) are spotlighted as next generation display devices with the highest practicality among flat panel display devices. In particular, plasma display panels (PDPs) have higher luminance and wider viewing angles than liquid crystal displays, and thus have wide applicability as thin, large displays such as outdoor advertising towers, wall TVs, and theater displays.

1 illustrates a cross-sectional structure of a general PD, in which a Y electrode and a Z electrode are formed on the same surface of the front glass substrate 1, a dielectric layer is formed on the Y electrode and the Z electrode by a printing method, and the dielectric layer 2 Cross-talk with the superstructure on which the protective layer is formed by vapor deposition, and the X electrode 12 on the rear glass substrate 11 of the superstructure, and adjacent cells between the X electrodes 12. The barrier rib 6 is formed to prevent the phenomenon, and the lower structure is formed by forming the phosphors 8, 9, and 10 around the barrier rib 6 and the X electrode 12 to form a space between the upper structure and the lower structure. The inert gas is enclosed in the structure so as to have a discharge region 5.

In such a structure, first, when a driving voltage is applied between the X electrode and the Y electrode, a counter discharge occurs between the X electrode and the Y electrode, and wall charges are generated on the surface of the protective layer of the upper structure. When the discharge voltages having opposite polarities are continuously applied to the Y electrode and the Z electrode and the driving voltage applied to the X electrode is interrupted, a predetermined potential difference between the Y electrode and the Z electrode is maintained by the wall charge, thereby maintaining the dielectric layer ( 2) and the surface discharge occurs in the discharge region on the surface of the protective layer 3. As a result, ultraviolet rays 7 are generated from the inert gas in the discharge region. The ultraviolet rays 7 excite the phosphors 8, 9, and 10, and color display is performed by the emitted phosphors 8, 9, and 10.

That is, while the electrons inside the discharge cell accelerate to the cathode (-) by the applied driving voltage, helium (He) is filled with the inert mixed gas filled with the pressure of about 400 to 500 torr in the discharge cell. As the main component, it collides with a Penning mixed gas to which xenon (Xe), neon (Ne) gas, etc. are added, and the inert gas is excited to generate ultraviolet rays having a wavelength of 147 nm. The ultraviolet light 7 collides with the phosphors 8, 9, and 10 surrounding the lower electrode 12 and the partition wall 6 to emit light in the visible light region.

The PD discharges the cells constituting the pixel by controlling the application of voltages to the X electrode, the Y electrode, and the Z electrode, and the amount of light emitted by the discharge changes the discharge time of the cell. Adjust In other words, the gray scale required for image display is realized by varying the length of time each cell is discharged within the time required to display the entire image (1/30 second in the case of NTSC TV signal). . At this time, the brightness of the screen is determined by the brightness when each cell is discharged to the maximum. In addition, in order to maximize the luminance of the PD screen, it is necessary to keep the discharge time of the cell as long as possible within the time necessary for constructing one screen.

FIG. 2 is a block diagram showing a schematic structure of a PDP including a driving circuit unit, and shows a panel, an X electrode driver, a Y electrode driver, and a Z electrode driver. The X electrode formed in each cell of the PD shown in FIG. 1 is connected to the X electrode driver to receive an address voltage, and the Y electrode is connected to the Y electrode driver to receive a scan voltage. The electrode is connected to the Z electrode driver to receive a sustain voltage.

The controller of the PD drive circuit unit configured as shown in FIG. 2 receives various control signals such as clock signal, RGB data, vertical synchronization signal, and horizontal synchronization signal from the outside, generates scan data, and applies them to the Y electrode driver. The address data is generated and applied to the X electrode driver. Accordingly, the X electrode, the Y electrode, and the Z electrode are driven in accordance with the signals applied to the respective drivers to display an image on the PD. As described above, there are various methods of displaying the screen by discharging each cell of the PD, and generally used methods include a subfield method and a line erase scanning method.

The subfield method is a method of implementing one screen by setting a screen displayed by discharge of a cell to one sub-screen, and controlling the Y electrode driver and the Z electrode driver to overlap several sub-screens. In such a subfield method, a plurality of subpictures are sequentially gathered to form a single image. In this case, the number of subpictures is equal to the number of gradation bits of the image. That is, if the gray level of the image implemented on the screen is 8 bits, the number of subscreens implemented by the subfield method is 8 sheets. FIG. 3A illustrates a waveform applied to each electrode of the PDP, and FIG. 3B illustrates a subfield type PDP driving method showing a scanning sequence of each PD cell according to the waveform of FIG. 3A.

First, the subfield method applies a voltage of a digital video signal of one bit to all cells of a PD to generate a first sub-picture of all cells having the same luminance. Then, the voltage of the next bit of the digital video signal is applied to generate another second sub-screen in which all cells have the same brightness. At this time, the luminance of the discharge cells constituting the first sub-screen is the same and the luminance of all the discharge cells constituting the second sub-screen is the same, and the luminance of the first sub-screen and the second sub-screen are different.

Each sub-picture generated by one bit of video signal has the highest sub-picture with the highest luminance bit, the lowest sub-picture with the lowest luminance bit, and between the highest sub-picture and the lowest sub-picture. It consists of several sub-pictures by the middle bit. For example, an image having an 8-bit gradation may include a first sub-picture based on the most significant bit, an eighth sub-picture based on the least significant bit, and a second sub-picture that has been differentially divided by six intermediate bits. A total of eight subscreens, including the 4th, 5th, 6th subscreens, are displayed. The subfield method is to superimpose these eight sub-screens and to realize one complete screen by the afterimage effect of the human eye.

However, the subfield method not only has a problem of applying a write pulse to all the Y electrodes as in the line scanning method, but also has a problem of insufficient time for maintaining the discharge between each of the Y and Z electrodes as the number of horizontal electrodes increases. In addition, there is a problem in that a large amount of flicker occurs due to a large difference in discharge time between the sub-screen by the upper bits and the sub-screen by the lower bits when configuring the sub-screen.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object thereof is to provide a stable PDP driving method by improving contrast and reducing flicker than before.

1 is a cross-sectional view showing a cross-sectional structure of a typical PD.

2 is a block diagram showing a schematic structure of a typical PD with a driving circuit unit

3 is a view showing a PD field driving method of a subfield method.

4 is a waveform diagram showing a PDPI driving pulse of a line scanning method;

5 shows a first embodiment of the present invention;

6 shows a second embodiment of the present invention;

7 shows a third embodiment of the present invention;

The present invention is characterized in that the line scanning method and the subfield method are properly combined to adopt the advantages of the line scanning method and the subfield method to improve the contrast and to quickly drive the PD.

In the method for implementing a pixel of 8-bit gradation data, the PDP driving method of the present invention comprises the steps of implementing m-bit grayscale data in a subfield method and a line-scanning method of 8-m grayscale data. It consists of the steps to implement. At this time, m is 1 or more and has a range of less than 8.

In addition, the present invention can process not only 8-bit grayscale data but also more or less grayscale data. That is, in the method for driving a pixel of n-bit grayscale data, the PDP driving method of the present invention implements m-bit grayscale data in a subfield method and nm-bit grayscale data in a line scanning method. It consists of steps. At this time, m is 1 or more and n is larger than m.

Hereinafter, the PDIP driving method of the present invention is as follows.

First, if grayscale data of an image to be implemented in a PD is 8 bits, that is, 256 (2 ⁸ ) steps, the present invention implements the grayscale data of some of the 8 bits in a subfield method. In addition, the present invention implements the grayscale data of the remaining bits except the grayscale data implemented by the subfield method using the line scanning method.

In this case, the present invention is implemented in various embodiments according to the subfield method and the line scanning method.

(First embodiment)

The first embodiment of the present invention implements the upper bit grayscale data in the subfield method and implements the lower bit grayscale data in the line scanning method.

FIG. 5 illustrates that 8-bit grayscale data is input to implement grayscale data of the upper 5 bits in a subfield method and to implement the remaining 3 bits in a line scanning method. As a result, since one image is implemented with five subfields of subfields and eight (2 ³ ) line scanning subpictures, a total of 13 subpictures are displayed as one image.

Of course, in the first embodiment, the upper four bits may be implemented by subfield method by dividing the eight-bit grayscale data by four bits, and the lower four bits may be implemented by line scanning method. However, if 4 bits are implemented by the line scanning method, since 16 subscreens of 16 (2 ⁴ ) lines are implemented separately in addition to the 4 subfields, a total of 20 subscreens are displayed as one frame. do.

However, if the number of sub-screens for displaying one image is actually too large on the screen of the PDP, there is a problem that a load is placed on the driving circuit part of the PD. Accordingly, the first embodiment of the present invention should be implemented by properly arranging the number of grayscale data to be implemented in the subfield method and the number of grayscale data to be implemented in the line scanning method according to the grayscale data of the image implemented on the PDP screen.

This first embodiment is not necessarily implemented only when processing 8-bit grayscale data, but can be applied to process more or less grayscale data.

That is, the first embodiment may be implemented to implement image data of the upper m bits of the n-bit grayscale data by the subfield method, and implement the remaining n-m grayscale data by the line scanning method.

(Second embodiment)

The second embodiment of the present invention implements the upper bit grayscale data by the line scanning method and the lower bit grayscale data by the subfield method.

FIG. 6 illustrates that the 8-bit grayscale data is input and the upper 3 bits of grayscale data are implemented by the line scanning method, and the remaining 5 bits are implemented by the subfield method. As a result, since one image is implemented with 8 (2 ³ ) line-scanning sub-screens and 5 sub-field sub-screens, a total of 13 sub-screens are displayed as one image. The image displayed by the second embodiment is almost the same as the image displayed by the first embodiment. However, the second embodiment only reverses the order of the processing methods of the sub-screens compared with the first embodiment. That is, the first embodiment implements the upper bits in the grayscale data in the subfield method, but the second embodiment implements the upper bits in the grayscale data in the line scanning method.

Of course, the second embodiment may be implemented by dividing the 8-bit grayscale data by 4 bits as in the case of the first embodiment. However, in the second embodiment, as described above, the upper 4 bits are implemented by the line scanning method, and the lower 4 bits are implemented by the subfield method. As a result, the four sheets of the sub-field method in the sub-screen in addition to the scanning lines in the sub-screen system of 16: ⁽²⁴⁾ implemented separately, a total of 20 sheets of the sub-screen is displayed in one frame. This also causes a problem that a large load is applied to the drive circuit portion of the PD since the number of sub-screens for displaying one frame is too large.

Accordingly, the second embodiment of the present invention like the first embodiment also properly arranges the number of grayscale data to be implemented by the subfield method and the number of grayscale data to be implemented by the line scanning method according to the grayscale data of the image implemented on the PDIP screen. Should be implemented.

As in the case of the first embodiment, the second embodiment is not necessarily implemented only when processing the gradation data of 8 bits, but can be applied to process more or less gradation data.

That is, the second embodiment may be implemented to implement image data of the upper m bits of the n-bit grayscale data by the line scanning method, and implement the remaining n-m grayscale data by the subfield method.

(Third embodiment)

The third embodiment of the present invention implements a part of the upper bit gray level data and a part of the lower bit gray level data in a subfield method, and implements the middle bit gray level data in a line scanning method.

7 illustrates that the 8-bit grayscale data is input to implement the upper 3 bits of the grayscale data using the subfield method, the upper 3bits are implemented using the line scanning method, and the remaining lower 2 bits are implemented again using the subfield method. It is shown. As a result, one image is implemented with 8 (2 ³ ) line-scanning sub-pictures and 5 sub-fields sub-pictures as in the first and second embodiments, so that a total of 13 sub-pictures It is displayed as one image. The first embodiment implements the upper bits in the grayscale data in the subfield method, while the second embodiment implements the upper bits in the grayscale data in the line scanning method, while the third embodiment implements a part of the upper bits and the lower bits in the grayscale data. Some of the bits are implemented in the subfield method and the middle bit is implemented in the line scanning method.

In addition, the upper 3 bits and the lower 2 bits may be implemented by the subfield method, the upper 2 bits and the lower 3 bits may be implemented by the subfield method, and the uppermost 1 bit and the lower 4 bits may be implemented by the subfield method. Of course, the upper 4 bits and the lowest 1 bit may be implemented in a subfield method.

The third embodiment may be implemented by dividing the 8-bit grayscale data by 4 bits as in the case of the first and second embodiments. That is, according to the third embodiment, the upper 3 bits and the lowest 1 bit may be allocated to the subfield method, the upper 2 bits and the lower 2 bits may be allocated to the subfield method, and the uppermost 1 bit and the lower 3 bits may be assigned to the subfield. Can be assigned in a way.

If a total of 4 bits of grayscale data is implemented in the subfield method, 16 subscreens of 16 (2 ⁴ ) lines are implemented separately in addition to the 4 subfields of the subfield, so that a total of 20 subscreens It is displayed as an image. This also causes a problem that the load on the driving circuit part of the PD is excessive because the number of sub-screens for displaying one image is too large on the PD screen.

Accordingly, in the third embodiment of the present invention, like the first and second embodiments, the number of the grayscale data to be implemented in the subfield method and the number of the grayscale data to be implemented in the line scanning method are determined according to the grayscale data of the image implemented on the PDIP screen. Appropriate arrangements should be made.

As in the case of the first and second embodiments, the third embodiment is not necessarily implemented only when processing the gradation data of 8 bits, but can be applied to process gradation data of more or less. That is, the third embodiment may be implemented to implement the image data of the upper m bits of the n-bit grayscale data by the line scanning method, and implement the remaining n-m grayscale data by the subfield method.

According to the present invention, the line scanning method and the subfield method, which are conventional PD driving methods, are mixed, so that the operation speed and the contrast of the screen can be improved. In addition, by implementing a part of the gradation data by the line scanning method, there is an advantage that the contrast of the screen can be improved compared to performing the entire gradation data by the line scanning method. The reason is that the conventional PDP driving method requires write discharge for each subfield screen, but the present invention includes a part of the line scanning method that can express the gray levels of several bits with one write discharge, thereby reducing the number of write discharges. Because. In addition, by implementing a part of the gradation data in the subfield method, the discharge holding time is shorter than that in performing the entire gradation data in the subfield method, thereby reducing the flicker and power consumption of the screen.

Claims (16)

In the plasma display panel which implements each pixel having 8-bit grayscale data on the screen, Implementing m-bit grayscale data of the 8-bit grayscale data in a subfield method; And, And a step of realizing the 8-m-bit grayscale data except the grayscale data implemented by the subfield method using a line scanning method. The method of claim 1, wherein the implementing of the subfield method comprises performing higher bit gray level data. The method of claim 1, wherein the implementing of the line scanning method comprises implementing low-bit grayscale data. The method of claim 1, wherein the subfield method is implemented. Performing grayscale data of the most significant bit to the nth bit among the 8-bit grayscale data; And, A method of driving a plasma display panel, comprising the steps of: performing gradation data of n + m + 1 th bit to least significant bit. The method of claim 4, wherein the implementing of the line scanning method And performing the grayscale data of the n + 1th to n + mth bits after the upper n-bit grayscale data is implemented in the subfield method. The method of driving a plasma display panel according to any one of claims 4 to 5, wherein n is in a range of 4 or less. The method of claim 1, wherein the implementing of the line scanning method comprises performing the most significant bit to the mth bit among the 8-bit grayscale data. The method of claim 7, wherein the implementing of the subfield method comprises performing low-level m + 1 th bit to the least significant bit of the 8-bit grayscale data. . The method of claim 1, wherein m is five. In a plasma display panel that implements n bits of grayscale data on a screen, Implementing m-bit grayscale data in the n-bit grayscale data in a subfield method; And n-m-bit grayscale data in the line-scanning method among the n-bit grayscale data. The method of claim 10, wherein the implementing of the subfield method comprises sequentially executing grayscale data. The method of claim 10, wherein the implementing of the line scanning method comprises implementing low-bit grayscale data. The method of claim 10, wherein the implementing of the line scanning method comprises performing n-m-bit grayscale data sequentially from the most significant bit of the n-bit grayscale data. The method of claim 13, wherein the subfield method is implemented by performing m-bit grayscale data from the least significant bit to the reverse order of the n-bit grayscale data. The method of driving a plasma display panel according to claim 10, wherein m is 1 or more. The method of claim 10, wherein n is larger than m.