KR100522707B1 - Driving method for plasma display panel - Google Patents

Abstract

In the method of driving a plasma display panel according to the present invention, one TV field is divided into a plurality of subfields having predetermined luminance weights, and each subfield is initialized to a state of each cell by a ramp up signal and a ramp down signal. A method of driving a plasma display panel, comprising: a reset period to be set; an address period for selecting and addressing a cell to be turned on; and a sustain discharge period for sustaining discharge of an addressed cell; The luminance is controlled by varying the width of the first sustain pulse applied by the.

According to the driving method of the plasma display panel of the present invention, the gray scale expression power can be enhanced by subdividing the minimum unit light output in the sustain period.

Description

Driving method for plasma display panel {Driving method for plasma display panel}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel (PDP), and more particularly to a method of driving a plasma display panel for reducing false discharge.

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 as an example of the plasma display panel driving method 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 gradation level assigned to subfield 4 may be lowered from 8 to 6, and the gradation 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. The address electrode A, the common electrode X, and the scan electrode in one subfield SF in the ADS driving method of the AC PDP. The drive signal applied to (Y1 to Yn) is shown. 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.

According to the conventional driving method described above, the luminance in the PDP 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.

If a total of Nmax sustain pulses are supplied in one frame, the number Ni of sustain pulses allocated to the i-th subfield may be determined as in Equation 1 below.

Wi is the specific gravity of the i-th subfield, and? Wi is determined by the sum of the specific gravity of the subfields constituting one TV field. Since Ni must be an integer, a rounding operation is performed on Ni _real . This rounding operation may be referred to as a quantization or integerization process of the number of sustain pulses.

Through the quantization process, the number of sustain pulses is determined, and the amount of light emitted in the subfield is determined according to the number of sustain pulses.

In the conventional plasma display panel, the amount of light generated by one sustaining pulse is determined by the luminous efficiency, the shape of the driving waveform, and the driving voltage according to the panel design specification. Generally, the amount of emitted light of sustain discharge is known to be about 0.3 to 0.8 cd / m 2 at one sustain discharge.

In the conventional plasma display panel, a dithering technique or the like is used to display a low gradation lower than the luminance caused by a single sustain discharge light emission amount.

In addition, when Nmax is small, a quantization process of allocating a sustain pulse to a subfield may not represent a grayscale ratio allocated to the subfield by a sustain pulse allocated to the low gradation subfield.

As such, when the luminance is controlled only by the number of sustain pulses, the weights of the subfields cannot be further subdivided, and there is a problem in that low gradation power is lowered.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a method of driving a plasma display panel in which a gray scale display power is enhanced by subdividing a minimum unit light output in a sustain period.

According to an aspect of the present invention, there is provided a method of driving a display panel, wherein one TV field is divided into a plurality of subfields having predetermined luminance weights, and each subfield is divided into a ramp up signal and a ramp down signal. And a reset period for initializing the state of each cell, an address period for selecting and addressing a cell to be turned on and a cell for which it is not, and a sustain discharge period for sustaining discharge of the addressed cell. The luminance is controlled by varying the width of the first sustain pulse applied in the sustain discharge period of one subfield.

The width of the second sustain pulse applied in the sustain discharge period can be fixed.

Preferably, the first sustain pulse is variable within a range smaller than the width of the sustain pulse for emitting a constant unit light in the second and subsequent sustain pulses.

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

According to the present invention, a TV field is divided into a plurality of subfields having predetermined luminance weights, and each subfield is a reset period for initializing the state of each cell by a ramp up signal and a ramp down signal, and a cell to be turned on. The present invention relates to a method of driving a plasma display panel including an address period for selecting and addressing a cell that is not, and a sustain discharge period for sustaining and discharging an addressed cell. That is, the present invention relates to the address display separation driving method illustrated in FIG. 3.

The basic concept of the present invention is to control the luminance by varying the width of the first sustain pulse applied in the sustain discharge period PS.

5 is a light emitting pattern when a sustain discharge period is performed by a fixed sustain pulse width. In the case where the sustain pulse width applied in the sustain discharge period PS is constant, several sustain pulse periods are required until the unit emission per one sustain discharge pulse is stabilized. In other words, the light amount of the unit sustain pulse is output only after several sustain pulses are applied. In FIG. 5, the unit light L stabilized at the sixth sustain pulse is output. Herein, the first to fifth holding pulses show an increase in the amount of light gradually from the first holding light L1.

FIG. 6 is a plasma display such that a stable unit light L is output after the second sustain pulse by increasing the width of the first sustain pulse of the sustain discharge period PS for a predetermined period αT _p to solve the problem of FIG. 5. Example of driving a panel. The width of the first sustaining pulse is applied very long so that wall charges are sufficiently formed after the first sustaining discharge, thereby stabilizing the unit light after the second sustaining pulse.

The basic concept of the present invention is to control the luminance by varying the width of the first sustain pulse applied in the sustain discharge period PS.

For example, after the second sustain pulse as shown in FIG. 6, the gray level expressive power is improved by appropriately controlling the width of the sustain pulse within a range smaller than the width αT _p of the first sustain pulse to allow stable unit light L to be output. will be. In particular, this gray scale expression is more effective in the low gray subfield.

The first sustain pulse width determines the period from the first sustain discharge L1 to the stabilized unit light L output. The longer the width of the first sustain pulse is, the more wall charges are formed after the first sustain discharge, so that the period until the unit light is stably output is shortened. By using this phenomenon, it is possible to express the luminance more subdivided than the unit light L.

7 to 9 are waveform diagrams and light emitting patterns for explaining a plasma display panel driving method according to a preferred embodiment of the present invention.

Referring to FIGS. 7 and 8, it can be seen that by varying the width of the first sustain pulse in the sustain discharge period, luminance different from the quantized unit light L can be expressed.

Referring to Fig. 7, when 1.5Tp is applied as the first sustain pulse width, the stable unit light L is output from the fourth sustain pulse.

Referring to Fig. 8, when 2Tp is applied as the first sustain pulse width, the stable unit light L is output from the third sustain pulse.

Referring to Fig. 9, when 3Tp is applied as the first sustain pulse width, the stable unit light L is output from the second sustain pulse.

Referring to Fig. 5, when Tp is applied as the first sustain pulse width, stable unit light L is output from the sixth sustain pulse.

5 to 8, the sum of the light emission amounts until the stable unit light L is output is different, and the increase trend of the light emission amounts until the stable unit light L is output is different.

Therefore, by varying the width of the first sustaining pulse and appropriately selecting the number of sustaining pulses, it is possible to express the luminance even more finely than before.

If a total of Nmax sustain pulses are supplied in one frame, the number Ni of sustain pulses allocated to the i-th subfield may be determined as shown in Equation 2 below by the weight W _i .

[Ni] is a quantized value of Ni, for example, when Ni = 3.4, [Ni] = 3. Therefore, in this case, the quantization error Δ = 0.4, and the quantization error portion cannot be expressed by the sustain discharge pulse.

According to the present invention, it is possible to express the quantization error 0 <Δ <1 part.

That is, the quantized integer portion [Ni] is represented by the number of first sustain pulses and sustain pulses in FIG. 6, and the quantization error part Δ represents the number of sustain pulses while varying the first sustain pulse width in FIGS. 5, 7 and 8. It can express by selecting suitably.

The multiples of 1.5Tp, 2Tp, 3Tp and the like described in FIGS. 5 to 9 are for convenience of description and are not intended to limit the invention. Those skilled in the art will appreciate that depending on the structural and electrical properties of the plasma display panel, the drainage may be appropriately modified from the foregoing embodiments.

The method for driving a plasma display panel according to the present invention can also be embodied as computer readable codes 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. Even in the case of a device for driving a plasma display panel, its use is limited to a specific field of panel driving, and in reality, it is a kind of computer.

As described above, the logic controller 202 and the image processor 200 included in the plasma display panel driver shown in FIG. 2 are formed of integrated circuits including a memory and a processor therein to drive the panel. The implemented program can be stored in memory. In driving the panel, a program stored in a memory may be executed to perform the addressing and holding operation according to the present invention. Therefore, the integrated circuit in which the program for executing the panel driving method is stored should be interpreted as a kind of the recording medium.

In particular, the method of driving a plasma display panel is made by a schematic or ultra-high-speed integrated circuit hardware description language (VHDL) on a computer, and is implemented by an integrated circuit connected to a computer, for example, a field programmable gate array (FPGA). Can be. The recording medium includes such a programmable integrated circuit. In addition, the recording medium is a concept including an application specific integrated circuit (ASIC) implemented by an integrated circuit in which the method is implemented.

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. 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 driving method of the plasma display panel of the present invention, the gray scale expression power can be enhanced by subdividing the minimum unit light output in the sustain period.

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.

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 as an example of the plasma display panel driving method 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 light emitting pattern when a sustain discharge period is performed by a fixed sustain pulse width.

6 is a light emission pattern when the sustain discharge period is performed by extending the width of the first sustain pulse by a predetermined period.

7 to 9 are waveform diagrams and light emitting patterns for explaining a plasma display panel driving method according to a preferred embodiment of the present invention.

Claims (4)

One TV field is divided into a plurality of subfields having predetermined luminance weights, and each subfield is a reset period for initializing the state of each cell by a ramp up signal and a ramp down signal. A driving method of a plasma display panel comprising an address period for selecting and addressing a cell and a sustain discharge period for sustaining and discharging an addressed cell, the method comprising: And controlling the luminance by varying the width of the first sustain pulse applied in the sustain discharge period of the at least one subfield. The method of claim 1, And a width of the second sustain pulse applied during the sustain discharge period is fixed. The method of claim 2, wherein the first holding pulse, And a predetermined unit light of the second and subsequent sustain pulses is variable within a range smaller than a width of the sustain pulse for emitting light. A computer-readable recording medium having recorded thereon a program for executing the method of claim 1 on a computer.