KR100603304B1 - Panel driving method - Google Patents

Abstract

In the panel driving method according to the present invention, one frame includes a plurality of subfields, one subfield includes a reset period, an address period, and a sustain discharge period, and a scan electrode and a common electrode in the sustain discharge period. In a panel driving method for expressing gray scales by alternately applying a predetermined number of sustain pulses, the reset pulses applied to the scan electrodes and the common electrodes are toggled depending on whether the number of sustain discharge pulses allocated to the subfield is odd or even. Characterized in that. According to the panel driving method of the present invention, it is possible to apply even and odd effective holding pulses in the holding section, thereby improving the minimum luminance resolution. Therefore, a small number of sustain pulses is allocated to enhance the function of the low gradation subfield, where the minimum luminance resolution greatly affects the gradation expression power.

Such improvement in the minimum luminance resolution in the low gradation region reduces the application of dithering. As a result, it is possible to reduce side effects of deterioration of image quality and dithering noise such as lowering the spatial resolution of the original image in expressing low grayscale.

Description

Panel driving method

1 is a view showing the structure of a conventional three-electrode surface discharge plasma display panel.

FIG. 2 shows a typical driving apparatus of the plasma display panel shown in FIG. 1.

FIG. 3 shows a conventional address-display separation driving method for Y electrode lines of the plasma display panel of FIG. 1.

FIG. 4 is a timing diagram for explaining an example of a drive signal of the panel shown in FIG. 1.

5 is a waveform diagram illustrating a relationship between a sustain pulse applied to the scan electrode Y and the common electrode X and the amount of light emitted.

6A and 6B are waveform diagrams of two different types of subfields provided to implement a panel driving method for improving gray scale expression power according to the present invention.

7 illustrates an embodiment of a panel driving waveform for implementing a subfield applying an odd number of sustain pulses.

8 is an embodiment of a panel driving waveform for implementing a subfield applying an even number of sustain pulses.

The present invention relates to a panel driving method for displaying a screen by applying a sustain pulse to an electrode structure for forming a display cell such as a plasma display panel (PDP).

1 is a view showing the structure of a conventional three-electrode surface discharge plasma display panel.

Referring to FIG. 1, between the front and rear glass substrates 100 and 106 of a conventional surface discharge plasma display panel 1, address electrode lines A ₁ , A ₂ ,..., A _m , Dielectric layers 102 and 110, Y electrode lines Y ₁ , ..., Y _n , X electrode lines X ₁ , ..., X _n , fluorescent layer 112, barrier rib 114, and As a protective layer, the magnesium monoxide (MgO) layer 104 is provided, for example.

The address electrode lines A ₁ , A ₂ ,..., A _m are formed in a predetermined pattern on the front side of the rear glass substrate 106. The lower dielectric layer 110 is applied in front of the address electrode lines A ₁ , A ₂ ,..., A _m . In front of the lower dielectric layer 110, barrier ribs 114 are formed in a direction parallel to the address electrode lines A ₁ , A ₂ ,..., A _m . The partition walls 114 function to partition the discharge area of each display cell and to prevent optical interference between the display cells. The fluorescent layer 112 is formed between the partition walls 114.

The X electrode lines X ₁ , ..., X _n and the Y electrode lines Y ₁ , ..., Y _n are address electrode lines A ₁ , A ₂ , ..., A _m . It is formed in a predetermined pattern on the back of the front glass substrate 100 to be orthogonal to the. Each intersection sets a corresponding display cell. Each X electrode line (X ₁ , ..., X _n ) and each Y electrode line (Y ₁ , ..., Y _n ) are transparent electrode lines (X _na ) made of a transparent conductive material such as indium tin oxide (ITO). , Y _na ) and metal electrode lines X _nb and Y _nb for increasing conductivity may be formed. The front dielectric layer 102 is formed by applying the entire surface to the rear of the X electrode lines (X ₁ ,..., X _n ) and the Y electrode lines (Y ₁ ,..., Y _n ). A protective layer 104 for protecting the panel 1 from a strong electric field, for example, a magnesium monoxide (MgO) layer, is formed by applying a front surface to the back of the front dielectric layer 102. The plasma forming gas is sealed in the discharge space 108.

A driving scheme generally applied to such a plasma display panel is a method in which initialization, address, and display holding steps are sequentially performed in a unit sub-field. In the initialization step, the charge states of the display cells to be driven are made uniform. In the address step, the charge state of display cells to be selected and the charge state of display cells not to be selected are set. In the display holding step, display discharge is performed in the display cells to be selected. At this time, a plasma is formed from the plasma forming gas of the display cells performing display discharge, and the fluorescent layer 112 of the display cells is excited by ultraviolet radiation from the plasma to generate light.

2 illustrates a general driving device of the plasma display panel of FIG. 1.

Referring to the drawings, a typical driving device of the plasma display panel 1 includes an image processor 200, a controller 202, an address driver 206, an X driver 208, and a Y driver 204. The image processing unit 200 converts an external analog image signal into a digital signal, and internal image signals, for example, 8-bit red (R), green (G) and blue (B) image data, clock signals, vertical and horizontal, respectively. Generate synchronization signals. The controller 202 generates the driving control signals SA, SY, and SX according to the internal image signal from the image processor 200. The address driver 206 processes the address signal SA among the drive control signals SA, SY, and SX from the controller 202 to generate a display data signal, and generates the display data signal through the address electrode lines. To apply. The X driver 208 processes the X driving control signal SX among the driving control signals SA, SY, and SX from the controller 202 and applies the X driving control signal SX to the X electrode lines. The Y driver 204 processes the Y driving control signal SY among the driving control signals SA, SY, and SX from the controller 202 and applies the Y driving control signal SY to the Y electrode lines.

As a driving method of the plasma display panel 1 having the structure described above, an address-display separation driving method which is mainly used is disclosed in US Pat.

FIG. 3 illustrates a conventional address-display separation driving method for Y electrode lines of the plasma display panel of FIG. 1.

Referring to the drawings, a unit frame may be divided into a predetermined number, for example, eight subfields SF1, ..., SF8 to realize time division gray scale display. Each subfield SF1, ..., SF8 is divided into a reset section (not shown), an address section A1, ..., A8, and a sustain discharge section S1, ..., S8. do.

In each address section A1, ..., A8, a display data signal is applied to the address electrode lines AR1, AG1, ..., AGm, ABm in FIG. Scan pulses corresponding to..., Yn) are sequentially applied.

In each sustain discharge section S1, ..., S8, pulses for display discharge alternately in the Y electrode lines Y1, ..., Yn and the X electrode lines X1, ..., Xn. Is applied to cause display discharge in discharge cells in which wall charges are formed in the address periods A1, ..., A8.

The luminance of the plasma display panel is proportional to the number of sustain discharge pulses in the sustain discharge sections S1, ..., S8 occupied in the unit frame. When one frame forming one image is represented by eight subfields and 256 gray levels, each subfield is sequentially held at a ratio of 1, 2, 4, 8, 16, 32, 64, and 128 in order. The number of pulses can be assigned. In order to obtain luminance of 133 gray levels, cells may be addressed and sustained and discharged during the subfield 1 period, the subfield 3 period, and the subfield 8 period.

The number of sustain discharges allocated to each subfield may be variably determined according to the weights of the subfields according to the APC (Automatic Power Control) step. In addition, the number of sustain discharges allocated to each subfield is. Various modifications are possible in consideration of gamma characteristics or panel characteristics. For example, the gray level assigned to subfield 4 may be lowered from 8 to 6, and the gray level assigned to subfield 6 may be increased from 32 to 34. In addition, the number of subfields forming one frame can be variously modified according to design specifications.

FIG. 4 is a timing diagram for explaining an example of a driving signal of the panel shown in FIG. 1. X) and drive signals applied to the scan electrodes Y1 to Yn. Referring to FIG. 4, one subfield SF includes a reset period PR, an address period PA, and a sustain discharge period PS.

The reset period PR initializes the wall charge state of all cells by applying reset pulses to the scan lines of all groups and forcibly performing a write discharge. The reset period PR is performed before entering the address period PA, which is carried out over the entire screen, thus making it possible to create a wall distribution of wall charges with a fairly even and desired distribution. The cells initialized by the reset period PR have similar wall charge conditions in the cells. The address period PA is performed after the reset period PR is performed. At this time, in the address period PA, the bias voltage Ve is applied to the common electrode X, and the scan electrodes Y1 to Yn and the address electrodes A1 to Am are simultaneously turned on at the cell positions to be displayed. Select the display cell. After the address period PA is performed, the sustain pulse Vs is alternately applied to the common electrodes X and the scan electrodes Y1 to Yn to perform the sustain discharge period PS. During the sustain discharge period PS, a low level voltage VG is applied to the address electrodes A1 to Am. In PDP, the brightness is adjusted by the number of sustain discharge pulses. If the number of sustain discharge pulses in one subfield or one TV field is large, the luminance increases.

Note the sustain period PS in the subfield SFn. After the scan pulse is applied to the Y electrode in the address period PA, the sustain pulse is applied to the Y electrode in the sustain period PS, and then the sustain pulse is alternately applied to the X electrode and the Y electrode.

If the last sustain pulse is applied to the X electrode in the sustain period PS of SFn, even 2N sustain pulses are applied in the sustain period PS of SFn.

In If the last sustain pulse is applied to the X electrode in the sustain period (PS) of the SF _n, the sustain period (PS) of the SF _n is applied to the odd-numbered (2N + 1) of the sustain pulses compared. However, the pulse applied to the X electrode at the head of the reset period PR of the next subfield SF _{n + 1} acts like the sustain pulse of SF _n , resulting in an effect that an even number of sustain pulses are applied.

If reset pulses of the same waveform are applied to each electrode in each subfield, only even number of sustain pulses are applied in the sustain period.

This results in the application of substantially even number of sustain pulses even if odd or even number of sustain pulses are allocated by the quantization of the sustain pulses, and there is a problem in that gradations due to the odd number of sustain pulses cannot be expressed.

An object of the present invention is to provide a panel driving method for selectively applying an even number of sustain pulses and an odd number of sustain pulses in a sustain period of the panel drive.

In the panel driving method of the present invention for achieving the above technical problem, one frame includes a plurality of subfields, one subfield includes a reset period, an address period, and a sustain discharge period, the sustain discharge period The panel driving method expresses the gray scale by alternately applying a predetermined number of sustain pulses to the scan electrode and the common electrode. The reset waveform is toggled between the scan electrode and the common electrode between at least two subfields.

The panel driving method is characterized in that the reset pulse applied to the scan electrode and the common electrode is toggled according to whether the number of sustain discharge pulses allocated to the subfield is odd or even.

The panel driving method includes: (a) determining whether the sustain discharge pulse allocated in the subfield is odd or even; (b) if the sustain discharge pulse allocated in the subfield is odd, applying a reset pulse equal to the reset pulse of the current subfield to the scan electrode and the common electrode in the reset period of the next subfield; And (c) if the sustain discharge pulse allocated in the subfield is an even number, applying the reset pulse of the current subfield and the reset pulse toggled in the reset period of the next subfield to the scan electrode and the common electrode. .

Hereinafter, the configuration and operation of a panel driving method according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

5 is a waveform diagram illustrating a relationship between a sustain pulse applied to the scan electrode Y and the common electrode X and the amount of light emitted.

Since the sustain pulses applied to one subfield are supplied to the scan electrode once as an XY sustain pulse pair based on the common electrode once, the N sustain pulse pairs cause 2N sustain discharges. Therefore, for example, if the luminance of 0.5 cd / m 2 is generated by one sustain discharge, the minimum luminance resolution of the sustain discharge is 2 * 0.5 = 1 cd / m 2. This means that the luminance increase in low gradation cannot be less than 1 cd / m 2. In order to overcome the limitation of the luminance resolution of the PDP, the luminance resolution is increased by dithering such as error diffusion. However, such use of dithering degrades the spatial resolution of the original image, resulting in deterioration of image quality and dithering noise.

6A and 6B are two different types of subfields provided to implement a panel driving method for improving gray scale expression power according to the present invention.

FIG. 6A illustrates a subfield SF _A of the first type, in which a lamp reset pulse is applied to the Y electrode in the reset period PR. 6B illustrates a second type subfield SF _B in which a lamp reset pulse is applied to the X electrode in the reset section PR. 6A and 6B show that the reset pulses applied in the reset section PR are toggled with each other.

FIG. 7 illustrates an embodiment of a panel driving waveform for implementing subfields to which odd number of sustain pulses are applied.

7 forms a panel driving waveform in which a subfield SF _A of the first type of FIG. 6A and a subfield SF _B of the second type of FIG. 6B are combined.

Note the reset period of the first subfield SF _A and the second subfield SF _B. It can be seen that the reset waveforms applied to the X electrode and the Y electrode are toggled between the first subfield SF _A and the second subfield SF _B.

Three Y electrode sustain pulses and three X electrode sustain pulses alternately applied in the sustain period of the first subfield SF _A , and the reset pulses of the Y electrode at the head of the second subfield SF _B are sustained and discharged. It works. In other words, the reset pulse of the Y electrode positioned at the head of the second subfield SF _B is alternately applied to the Y electrode after the last sustain pulse is applied to the X electrode in the first subfield SF _A. It works like this. Accordingly, sustain discharge such as seven sustain pulses applied between the first subfield SF _A and the second subfield SF _B occurs.

As a result, in the example of FIG. 7, when a reset waveform is toggled between the Y electrode and the X electrode between two adjacent subfields, an odd number of sustain pulses 2N + 1 may be applied.

8 is an embodiment of a panel driving waveform for implementing a subfield applying an even number of sustain pulses.

In the embodiment of FIG. 8, two subfields SF _A of the first type of FIG. 6A are connected to each other to form a combined panel driving waveform.

Three Y electrode sustain pulses and three X electrode sustain pulses alternately applied in the sustain section of the first subfield SF _A perform a sustain discharge action. Therefore, sustain discharge such as six sustain pulses applied between the first subfield SF _A and the second subfield SF _B occurs.

As a result, in the example of FIG. 8, if the reset waveforms remain the same between two adjacent subfields, even number 2N of sustain pulses may be applied.

For example, if the number of sustain discharge pulses of the subfield is even, odd, even, or odd, the subfield type may be implemented by connecting SF _A → SF _A → SF _B → SF _B → SF _A.
On the other hand, it is determined in the logic controller 202 of FIG. 2 whether the number of sustain discharge pulses in the subfield is even or odd, and whether or not the reset pulse is toggled is determined by the Y driver 204 according to whether it is even or odd. It is expressed in the Y driving control signal SA applied to the X driving control signal SX applied to the X driving unit 208.

In the above-described embodiments, the lamp reset for inducing weak discharge is applied in the reset period PR, but the skilled person can perform the same function in the sustain period even if the square wave reset is applied instead of the lamp reset. I will understand that.

In practice, the application of the maintenance pulses by strictly distinguishing whether the number of the sustain pulses is even or odd is that the low gradations assigned the less number of sustain pulses than the high gradation subfields to which a large number of sustain pulses are assigned. There is a more desirable effect in the subfield of.

In particular, when the average signal level is high, the total number of sustain pulses is reduced by automatic power control (APC), and the number of sustain pulses is further reduced in the low gradation subfield. In this situation, if only substantially even sustain pulses are expressed as in the prior art, there is a big limitation in expressing the low gradation region. In order to overcome this problem, dithering or the like is employed, which degrades the spatial resolution of the original image, resulting in deterioration of image quality and dithering noise.

Therefore, it is desirable to improve the minimum luminance resolution possible. According to the present invention, there is provided a panel driving method that can substantially realize the quantization result of a sustain pulse.

The invention can also be embodied as computer readable code on a computer readable recording medium. Computer-readable recording media include any type of recording device that stores programs or data that can be read by a computer system. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, hard disk, floppy disk, flash memory, optical data storage, and the like. Here, the program stored in the recording medium refers to a series of instruction instructions used directly or indirectly in an apparatus having an information processing capability such as a computer to obtain a specific result. Thus, the term computer is used to mean all devices having an information processing capability for performing a specific function by a program, including a memory, an input / output device, and an arithmetic device, regardless of the name actually used. In the case of a device for driving a panel, its use is limited to a specific field of panel driving, and in reality, it is a kind of computer.

In particular, the panel driving method according to the present invention is written in a schematic or ultra-high-speed integrated circuit hardware description language (VHDL) or the like on a computer, and connected to a computer-programmable integrated circuit such as a field programmable gate array (FPGA). Can be implemented. The recording medium includes such a programmable integrated circuit.

The best embodiments have been disclosed in the drawings and specification above. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. In particular, in the above-described embodiments, the lamp reset is applied to induce weak discharge in the reset period PR. However, those skilled in the art can perform the same function in the sustain period even if the square wave reset is applied instead of the lamp reset. I will understand.

Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, according to the panel driving method of the present invention, it is possible to apply even and odd effective holding pulses in the holding section, thereby improving the minimum luminance resolution. Therefore, a small number of sustain pulses is allocated to enhance the function of the low gradation subfield, where the minimum luminance resolution greatly affects the gradation expression power.

Such improvement in the minimum luminance resolution in the low gradation region reduces the application of dithering. As a result, it is possible to reduce side effects of deterioration of image quality and dithering noise such as lowering the spatial resolution of the original image in expressing low grayscale.

The invention is not limited to the examples described above and represented in the drawings. Those skilled in the art taught by the above-described embodiments, many modifications to the above-described embodiments are possible by substitution, erasure, merging, etc. within the scope and object of the present invention described in the following claims.

Claims (3)

One frame includes a plurality of subfields, one subfield includes a reset period, an address period, and a sustain discharge period, and a predetermined number of sustain pulses are alternately applied to a scan electrode and a common electrode in the sustain discharge period. In the panel driving method for expressing the gradation by applying, And a reset waveform is toggled between the scan electrode and the common electrode between at least two subfields. The method of claim 1, And a reset pulse applied to the scan electrode and the common electrode according to whether the number of sustain discharge pulses allocated to the subfield is odd or even. The method of claim 2, (a) determining whether the sustain discharge pulse allocated in the current subfield is odd or even; (b) if the sustain discharge pulse allocated in the current subfield is an even number, applying a reset pulse equal to the reset pulse of the current subfield to the scan electrode and the common electrode in the reset period of the next subfield; And (c) if the sustain discharge pulse allocated in the subfield is odd, applying the reset pulse of the current subfield and the reset pulse toggled in the reset period of the next subfield to the scan electrode and the common electrode. Panel driving method.

Images