KR100396164B1 - Method and Apparatus For Drivingt Plasma Display Panel - Google Patents

Abstract

The present invention relates to a method and apparatus for driving a plasma display panel for adjusting grayscale by adjusting a slope of a sustain pulse.

The method and apparatus for driving the plasma display panel adjust the inclination at the rising edge or the falling edge of the sustain pulse, and supply the sustain pulse to the plasma display panel to express the gray scale.

Description

Method and apparatus for driving plasma display panel {Method and Apparatus For Drivingt Plasma Display Panel}

The present invention relates to a method for driving a plasma display panel, and more particularly, to a method and apparatus for driving a plasma display panel for adjusting gray scale by adjusting a slope of a sustain pulse.

Recently, a plasma display panel (PDP), which is easy to manufacture a large panel, has attracted attention as a flat panel display device. The plasma display panel obtains a discharge by adjusting a voltage applied between an address electrode and a scan / sustain electrode and a common sustain electrode of a cell constituting a pixel, and the amount of light discharged is displayed by controlling the discharge period in the cell. Done. The full screen displays the write pulse for inputting the digital image signal to the address electrode, the scan / sustain electrode and the common sustain electrode of each cell, the scan pulse for scanning, the sustain pulse for maintaining the discharge, and the discharge of the discharged cell. It is obtained by applying an erase pulse for stopping to drive in a matrix form. Gray level required for image display enables different lengths of time each cell is discharged within a given time (1/30 second for NTSC TV signals) required to display the entire image. In this case, the brightness of the screen is determined by the brightness when each cell is driven to the maximum, and in order to increase the brightness, a driving circuit capable of keeping the discharge time of the cell as long as possible within a given time should be designed. Contrast, which is the difference in contrast, is determined by the brightness and brightness of the background. In order to increase the contrast, not only the background needs to be darkened but also the brightness needs to be increased. For a flat panel display for HDTV, 256 gray levels are required, the resolution must be 1280 × 1024 or more, and the contrast under 200 lux illumination needs 100: 1 or more. Therefore, an 8-bit RGB signal is required for the video digital signal required for displaying 256 gray levels, and the discharge time of the cell must be kept as long as possible in order to obtain the required luminance and contrast. The gray scales include a line scanning method and a subfield method. Among the three-electrode AC surface-discharge plasma display panels, the method that is currently attracting the most attention is the subfield method.

As the plasma display panel, a three-electrode alternating surface discharge plasma display panel driven by an alternating voltage is representatively shown in FIG.

Referring to FIG. 1, a three-electrode AC surface discharge type plasma display panel includes a scan / sustain electrode 12Y and a common sustain electrode 12Z formed on an upper substrate 10, and an address formed on a lower substrate 18. An electrode 20X is provided. The upper dielectric layer 14 and the passivation layer 16 are stacked on the upper substrate 10 having the scan / sustain electrode 12Y and the common sustain electrode 12Z side by side. Since the electrodes are separated from the discharge region, they extend the life of the cell and at the same time allow charge to accumulate in the cell, and use of the charge in the discharge cell lowers the discharge voltage applied to the external electrode. The wall charges generated during the plasma discharge are accumulated in the upper dielectric layer 14. The protective film 16 prevents damage to the upper dielectric layer 14 due to sputtering generated during the plasma discharge and discharge efficiency of secondary electrons. Will increase. 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 20X is formed, and the phosphor layer 26 is coated on the lower dielectric layer 22 and the partition wall 24. The address electrode 20X is formed in the direction crossing the scan / sustain electrode 12Y and the common sustain electrode 12Z. The partition wall 24 is formed in parallel with the address electrode 20X to prevent ultraviolet rays and 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. An inert gas for gas discharge is injected into the discharge space provided between the upper and lower plates 10 and 18 and the partition wall 24. In the case of the three-electrode AC surface discharge type plasma display panel having such an electrode structure, an AC voltage whose polarity is continuously reversed must be applied between the electrodes in order to maintain the discharge.

Referring to FIG. 2, first, each cell (at a point where the scan / sustain electrodes Y1 to Ym and the common sustain electrodes Z1 to Zm and the address electrodes X1 to Xn cross at right angles to each other) is described. 11) is configured. The scan / sustain electrodes Y1 to Ym are used for scanning the screen, and the common sustain electrodes Z1 to Zm are mainly used to maintain the discharge. The address electrodes X1 to Xn are mainly used for data input.

The driving waveform of the plasma display panel having the electrode structure is as shown in FIG. 3.

Referring to FIG. 3, a value of 0 (V) is applied to the scan / sustain electrodes Y1 to Ym during the period (a) during the reset period, and the front light pulse Twrp is applied to the common sustain electrodes Z1 to Zm. ) Is applied to generate an initial discharge between all common sustain electrodes Z1 to Zm and scan / sustain electrodes Y1 to Ym. In the section (b), the reset pulse Rstp is applied to the scan / sustain electrodes Y1 to Ym to generate a reset discharge, and then, in the section (c), the front erase pulses are applied to the common sustain electrodes Z1 to Zm. Terp) is applied to extinguish the discharge of all cells. Next, in the period (d) which is the address period, the same positive voltage is applied to the scan / sustain electrodes Y1 to Ym and the common sustain electrodes Z1 to Zm to prepare for the addressing started in the period (e). . In the section (e), scan pulses Scp are sequentially applied to the scan / sustain electrodes Y1 to Ym. When the scan pulse Scp is applied, the data pulse Dp of the anode is input to the cells belonging to the scan / sustain electrodes Y1 to Ym and the common sustain electrodes Z1 to Zm to form wall charges by discharge. As a result, sustain discharge is generated in a subsequent sustain period. When a data pulse Dp of 0 (V) is applied, sustain discharge is not performed in the sustain period. Lastly, in the sustain period (f), the same sustain pulse Sus is alternately applied to the scan / sustain electrodes Y1 to Ym and the common sustain electrodes Z1 to Zm to the cell determined in the address period. Sustain discharge is generated for each sustain pulse.

4 is a diagram illustrating a gray scale representation of a plasma display panel used in the related art.

Referring to FIG. 4, in the subfield method, one frame is divided into a plurality of subfields according to the gradation level, and each subfield is divided into a reset period, an address period, and a sustain period. Here, the reset period and the address period of each subfield are the same for each subfield, while the sustain period is 2 ⁿ (n = 0,1,2,3,4,5,6,7) in each subfield. Is increased. Thus, since the sustain period is different in each subfield, the gray scale of the image is expressed by adjusting the sustain period of each subfield, that is, the number of sustain discharges. Therefore, in order to configure each subfield, it takes time to scan all the scan / sustain electrodes Z1 to Zm and the common sustain electrodes Y1 to Ym, and each cell 11 is assigned to an average subfield. The discharge can be maintained only for a period of time reduced by the scanning time. The time required for scanning increases as the number of scan / sustain electrodes Z1 to Zm and common sustain electrodes Y1 to Ym increases, and during this time, discharge and sustain cannot be maintained, so that the brightness and contrast of the plasma display panel are reduced. The time required for injection needs to be reduced as much as possible. The length of the light emission period is adjusted by the number of sustain pulses, and the basic pulse shape thereof is as shown in FIG.

5 shows that the rectangular pulses are alternately input to the scan / sustain electrode and the common sustain electrode during the sustain period.

Conventionally, the method of adjusting the number of sustain pulses is used to correct grayscale. However, it was not easy to adjust the brightness adjustment between gradations as desired by the user. The basic brightness is limited to the number of pulses, making it impossible to display grayscale above or below any limit. In addition, if the number of pulses is adjusted to uniformly express grayscale, driving time increases.

Accordingly, an object of the present invention is to provide a method and apparatus for driving a plasma display panel for adjusting grayscale by adjusting a slope of a sustain pulse.

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

FIG. 2 is a layout view of electrodes of the three-electrode alternating surface discharge plasma display panel shown in FIG. 1; FIG.

3 is a view showing a driving waveform of the three-electrode alternating surface discharge plasma display panel shown in FIG. 1;

FIG. 4 is a diagram illustrating a gray scale representation of the three-electrode alternating surface discharge plasma display panel shown in FIG. 1; FIG.

FIG. 5 is a waveform diagram showing sustain pulses of the three-electrode alternating surface discharge plasma display panel shown in FIG. 1; FIG.

6 is a waveform diagram schematically showing waveforms of sustain pulses of a three-electrode alternating surface discharge type plasma display panel according to an embodiment of the present invention.

7 is a block diagram of a circuit implementing the sustain pulse shown in FIG.

Fig. 8 is a waveform diagram showing waveforms during a discharge period using sustain pulses according to the first embodiment of the present invention.

9 is a waveform diagram showing waveforms during a discharge period using sustain pulses according to a second embodiment of the present invention;

<Description of Symbols for Main Parts of Drawings>

10: upper substrate 11: cell

12Y: scan / sustain electrode 12Z: common sustain electrode

14,22 dielectric layer 15 spacer

16: protective film 18: lower substrate

20X: address electrode 24: partition wall

26 phosphor layer 28 pulse gradient generator

In order to achieve the above object, the driving method of the plasma display panel according to the present invention includes the step of adjusting the slope at the rising edge or falling edge of the sustain pulse, and supplying the sustain pulse to the plasma display panel. The driving apparatus of the plasma display panel according to the present invention includes a pulse slope generator for adjusting the slope at the rising edge or the falling edge of the sustain pulse according to the gray scale, and a switch for supplying the sustain pulse from the pulse slope generator to the plasma display panel. An element is provided.

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. 6 to 9.

The present invention enables the gray scale to be adjusted by controlling the inclination of the pulse as shown in FIG. 6 rather than the number of sustain pulses generated during plasma discharge, and also to control the luminance. There are two ways to adjust the grayscale by adjusting the slope of the sustain pulse: adjusting the ratio of the number of sloped pulses and normal pulses during the sustain discharge period, and adjusting the number of sloped pulses and the slope value of the pulses simultaneously. Can be divided.

Fig. 6 shows that the inclined pulse is applied to the scan / sustain electrode and the common sustain electrode within the sustain period.

Conventionally, although the brightness of light is represented by the number of pulses, in the present invention, the brightness of light is adjusted using the gradient value θ of the pulse. Here, the θ value can be determined by experiment, and can also be set differently according to the cell internal state.

If one regular spherical pulse shows a brightness of 1, a tilted pulse can show brightness of less than 1 by adjusting the value of θ.

First, the first embodiment of the present invention is a method of adjusting grayscale by the ratio of the number of gradient pulses and the number of normal pulses.

FIG. 7 is a block diagram for selecting a pulse, and is a circuit for selecting two different pulse outputs. The pulse gradient generator 28 and the switches SW1 and SW2 are provided. When the sustain discharge voltage is applied on the circuit, pulses selected by the first switch SW1 and the second switch SW2 are applied to the electrodes of the plasma display panel. The first switch SW1 selects a general rectangular pulse, and the second switch SW2 is connected in series with the pulse gradient generator 28 to select a pulse having a slope. Here, the first switch SW1 and the second switch SW2 are not operated at the same time but operated to apply a pulse according to a gray value to be displayed. Referring to FIG. 8, an inclination determined by an experiment or a state inside a cell is illustrated. The overall natural gray scale can be displayed by adjusting the brightness of the light emitted from one subfield by the ratio of M pulse pairs having N values and N rectangular pulse pairs. The smaller the light intensity is, the more the number of sloped pulses is inversely related to the luminance. Therefore, assuming subfields having the same sum of M and N, luminance increases when the number of M increases and the number of N decreases. On the contrary, the luminance increases when the number of M decreases and the number of N increases.

The second embodiment according to the present invention is a method of simultaneously adjusting the number of gradient pulses and the gradient value.

In the first embodiment, the brightness of light is adjusted only by the number of tilted pulses, but the method shown in FIG. 9 simultaneously adjusts the number of tilted pulses and the slope value of each pulse. Depending on the gray scale value to be expressed, the inclination value may be adjusted differently such as θ ₁ and θ ₂ . Here, the brightness is lowered when the tilt is adjusted below the tilt θ _threshold determined by the experiment, while the brightness is increased when the tilt is adjusted above the tilt θ _threshold . In addition, since the number of pulses with a gradient can be adjusted at the same time, the expression of the gray level is free.

As a result, the embodiment according to the present invention can adjust the luminance over a wider range by adjusting the slope value above or below the slope θ _threshold for stable sustain discharge or simultaneously adjusting the ratio of the pulses with the slope. .

As described above, according to the method and apparatus for driving the plasma display panel according to the present invention, the gray scale can be displayed in detail by adjusting the inclination value of the sustain pulse or the number of inclination pulses. In addition, when grayscale is displayed, the sustain discharge period required to display the correct grayscale can be kept constant. In the related art, it is impossible to display at low brightness because the basic brightness is limited. In the present invention, it is possible to display at low brightness by adjusting the inclination value, and the brightness is easily adjusted.

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 (5)

Adjusting the slope at the rising or falling edge of the sustain pulse, And supplying said sustain pulse to a plasma display panel. The method of claim 1, And adjusting the gray scale by adjusting the number of sustain pulses and the number of square wave pulses. The method of claim 1, And adjusting the gray scale by adjusting the number of the sustain pulses and the inclination of the sustain pulses. A pulse slope generator for adjusting the slope at the rising or falling edge of the sustain pulse, And a switch element for supplying the sustain pulse from the pulse slope generator to the plasma display panel. The method of claim 4, wherein And a second switch element configured to generate a square wave pulse by receiving a sustain voltage and to supply the square wave pulse to the plasma display panel.