KR20090044333A - Plasma display apparatus - Google Patents

Abstract

The present invention relates to a plasma display device.

The plasma display apparatus according to the first embodiment of the present invention receives a digital video signal from the outside and converts a frame into a plurality of subfields to display an image, and converts the digital video signal to a resolution of the plasma display panel. A converting video scan converter comprising: a driver for adjusting sustain discharge periods of a plurality of subfields to adjust contrast and brightness of an image irrespective of the converted digital video signal, wherein the driver comprises at least one of the plurality of subfields. And a control unit applying a sustain pulse to only one of the scan electrode and the sustain electrode in the sustain discharge period of one subfield.

Gradation, Video Scan Converter, Contrast, Luminance

Description

Plasma display device {PLASMA DISPLAY APPARATUS}

The present invention relates to a plasma display device.

In general, a plasma display panel (hereinafter referred to as "PDP") displays an image including a character or a graphic by emitting phosphors by 147 nm ultraviolet rays generated when a He + Xe or Ne + Xe inert mixed gas is discharged. Done.

1 is a perspective view showing the structure of a three-electrode AC surface discharge type PDP having a discharge cell structure arranged in a matrix form. Referring to FIG. 1, the three-electrode AC surface discharge type PDP 100 includes a scan electrode 11a and a sustain electrode 12a formed on the upper substrate 10, and an address electrode formed on the lower substrate 20. 22). Each of the scan electrode 11a and the sustain electrode 12a is formed of a transparent electrode, for example, indium tin oxide (ITO). Metal bus electrodes 11b and 12b for reducing resistance are formed in each of the scan electrode 11a and the sustain electrode 12a. An upper dielectric layer 13a and a passivation layer 14 are stacked on the upper substrate 10 on which the scan electrode 11a and the sustain electrode 12a are formed. Wall charges generated during plasma discharge are accumulated in the upper dielectric layer 13a. The passivation layer 14 prevents damage to the upper dielectric layer 13a by sputtering generated during plasma discharge and increases emission efficiency of secondary electrons. As the protective film 14, magnesium oxide (MgO) is usually used.

Meanwhile, the lower dielectric layer 13b and the partition wall 21 are formed on the lower substrate 20 on which the address electrode 22 is formed, and the phosphor layer 23 is formed on the surfaces of the lower dielectric layer 13b and the partition wall 21. Is applied. The address electrode 22 is formed in the direction crossing the scan electrode 11a and the sustain electrode 12a. The partition wall 21 is formed in parallel with the address electrode 22 to prevent ultraviolet rays and visible light generated by the discharge from leaking to the adjacent discharge cells. The phosphor layer 23 is excited by ultraviolet rays generated during plasma discharge to generate visible light of any one of red (R), green (G), and blue (B). An inert mixed gas such as He + Xe or Ne + Xe for discharging is injected into the discharge space of the discharge cell partitioned by the partition wall 21 between the upper substrate 10 and the lower substrate 20.

2 is a block diagram showing a driving apparatus of a conventional plasma display panel.

Referring to FIG. 2, a conventional PDP driving apparatus includes a D / A converter 32, a video signal processor 34, a VSC 36, and a PDP driver 40.

The D / A converter 32 converts a digital signal input from the outside into an analog signal and supplies it to the image signal processor 34.

The image signal processing unit 34 operates the luminance adjusting unit 34a and the contrast adjusting unit 34b contained therein according to the luminance and contrast control signals of the PDP user, that is, the PC mode or the AV mode of the screen. Adjust the brightness and contrast of the image displayed on the panel by adjusting the voltage level and / or gain of the analog signal input from (32).

The VSC 36 converts the analog signal input from the image signal processor 34 to match the resolution of the PDP and supplies the analog signal to the PDP driver 40. At this time, the analog signal is converted into a digital signal and input to the PDP driver 40. The PDP driver 40 corrects the digital signal input from the VSC 36 and supplies it to the panel. For example, the video signal of the digital signal is re-allocated for each subfield according to the brightness and contrast of the image adjusted by the image signal processor, and the luminance and contrast of the image are corrected and supplied to the panel. The panel displays a predetermined image corresponding to the digital signal.

Such a conventional PDP driving apparatus converts a digital signal input from the outside into an analog signal, and converts the analog signal into a digital signal again. At this time, the digital signal is converted into an analog signal in order to control the contrast and brightness of the digital signal-analog signal-digital signal, so that distortion and attenuation of the signal is generated. do.

On the other hand, in the gray scale representation method of the PDP, as shown in FIG. 3, one frame is driven by dividing into several subfields having different number of light emission, and each subfield is a reset period for uniformly generating a discharge and an address for selecting a discharge cell. It is divided into sustain periods for implementing gray scales according to periods and discharge times.

For example, when a picture is to be displayed with 256 gray levels, a frame period (16.67 ms) corresponding to 1/60 second is divided into eight subfields, and each of the eight subfields is an address period and a sustain period. Will be subdivided into 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. Will increase.

As described above, in the image gradation of the conventional PDP, the number of discharges generated in the sustain period of each subfield is adjusted to express the gradation, but more precisely, the gradation is represented according to the luminance weight assigned to each subfield.

That is, the first when the subfields (SF1) the luminance weight is the lowest ²⁰ set to a, a is supplied with the data pulses to the first sub-field (SF1) during the address period, the address electrode (X) for, in synchronization with the data pulse Scan pulses are sequentially supplied to the scan electrodes (Y). As the voltage difference between the data pulse and the scan pulse and the wall voltage in the cell are added, address discharge occurs in the cells to which the data pulse is applied. At this time, in the sustain period of the first subfield SF1, a sustain pulse corresponding to the luminance weight '2 ⁰ ' is alternately supplied to the scan electrode and the sustain electrode, so that the cells selected in the address period have the sustain pulse and the internal wall voltage added together. As a result, a discharge is generated to express gray scales.

However, such a conventional PDP gray level representation method has a brightness weight of 2 ⁰ or less that is, problems that do not express the gray level of 1 or less. That is, the conventional PDP is set to each of the subfields with the luminance weight of the natural number, and the luminance weight resulting from the combination of the subfields with the luminance weight of the natural number is also expressed as the natural number. Therefore, the conventional PDP gray scale expression method cannot express fine gray scales of less than or equal to the natural number, and thus there is a certain limitation in improving image quality.

SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma display device which is suitable for digital signal processing and at the same time expresses finer gray levels to improve image quality.

The plasma display apparatus according to the first embodiment of the present invention receives a digital video signal from the outside and converts a frame into a plurality of subfields to display an image, and converts the digital video signal to a resolution of the plasma display panel. A converting video scan converter, and a sustain discharge period of the plurality of subfields are adjusted to adjust contrast and brightness of the image irrespective of the converted digital video signal input to a driver, and among the plurality of subfields. And a control unit configured to apply a sustain pulse to only one of the scan electrode and the sustain electrode in the sustain discharge period of at least one subfield.

The plasma display apparatus according to the second embodiment of the present invention receives a digital video signal from the outside and divides one frame into a plurality of subfields to display an image, and the digital video signal is adapted to the resolution of the plasma display panel. A video scan converter for converting, to adjust the sustain discharge period of the plurality of subfields to adjust the contrast and the brightness of the image irrespective of the converted digital video signal input to the driving unit, and among the plurality of subfields. And a control unit which does not apply a sustain pulse to either of the scan electrode and the sustain electrode so that sustain discharge does not occur in the sustain period of at least one subfield.

A plasma display device according to a third embodiment of the present invention receives a digital video signal from the outside and converts a frame into a plurality of subfields to display an image, and converts the digital video signal to a resolution of the plasma display panel. A converting video scan converter and a sustain discharge period of the plurality of subfields are adjusted to adjust contrast and brightness of the image irrespective of the converted digital video signal input to a driving unit, and the lowest of the plurality of subfields. And a control unit such that the width of the first sustain pulse applied to the scan electrode and the sustain electrode in the sustain discharge period of the gray level subfield is smaller than the width of the second sustain pulse applied to the sustain discharge period of another subfield.

The present invention prevents signal distortion and attenuation by not converting a digital signal into an analog signal, and simultaneously improves the image quality of the plasma display panel by expressing finer gray levels by giving a subfield a luminance weight of less than a natural number. It works.

4 is a view showing a driving apparatus of a plasma display panel according to an embodiment of the present invention.

Referring to FIG. 4, the driving apparatus of the PDP according to the embodiment of the present invention includes a VSC 42 and a PDP driving unit 44. The VSC 42 receives a digital video signal from the outside, converts the received digital signal (ie, video data) to match the resolution of the PDP panel, and supplies the converted digital signal to the PDP driver 44. The PDP driver 44 corrects the digital signal input from the VSC 42 and supplies it to the panel.

That is, the PDP driver 44 processes the digital signal according to a control signal of the PDP user, for example, a control signal input from a remote controller or a control panel. In this case, the PDP driver adjusts the sustain discharge period to adjust the brightness and contrast of the image regardless of the digital video signal converted by the video scan converter.

Therefore, since the digital signal is not converted into an analog signal in order to control the contrast and brightness of the image, signal distortion and attenuation do not occur.

The PDP driver 44 includes a first inverse gamma correction unit 46A, a gain control unit 48, an error diffusion unit 50, a subfield mapping unit 52, a data alignment unit 54, and a second unit as shown in FIG. An inverse gamma correction unit 46B, an APL (Avarage Picture Level) unit 56, a control unit 58, a panel 60, a contrast adjustment unit 62, and a luminance adjustment unit 64 are provided.

The first and second inverse gamma correction units 46A and 46B perform inverse gamma correction on the gamma corrected video signal (digital signal) to linearly convert luminance values according to grayscale values of the image signal.

The APL unit 56 receives the video data corrected by the second inverse gamma correction unit 46B and generates an N-stage signal for adjusting the number of sustain pulses. The gain control unit 48 amplifies the video signal corrected by the first inverse gamma correction unit 46A by the effective gain and then supplies it to the error diffusion unit.

The error diffusion unit 50 finely adjusts the luminance value by diffusing an error component of a cell into adjacent cells. The subfield mapping unit 52 reassigns the video data corrected from the error diffusion unit 50 for each subfield and supplies the data to the data alignment unit 54.

The data aligner 54 aligns the video signal to be supplied to the panel 60, and supplies the video signal to an address driving integrated circuit (IC) not shown.

The controller 58 generates a timing control signal based on the N-stage signal input from the APL unit 56, and supplies the generated timing control signal to the address driving IC, the scan driving IC, and the sustain driving IC of the panel 60. .

The contrast adjusting section 62 and the brightness adjusting section 64 adjust the number of discharges in the sustain period to adjust the contrast and the brightness of the image displayed on the panel.

That is, the luminance adjusting unit 64 adjusts the number of discharges in the sustain period as shown in FIG. 5 in response to a control signal input from the user. For example, in Fig. 6, sustain discharge is generated for half of the time of the sustain period allocated to the panel 60, and sustain discharge is not generated for the remaining time. When the sustain discharge occurs for half of the sustain period as described above, the luminance of the image displayed on the panel 60 is set to 50% of the normal discharge.

The brightness adjusting unit 64 of the present invention adjusts the sustain discharge time of all the subfields SF collectively to adjust the brightness of the image displayed on the panel 60.

On the other hand, the contrast adjusting unit 62 adjusts the contrast of the image displayed on the panel 60 by adjusting the sustain discharge period of at least one subfield SF as shown in FIG. For example, in FIG. 7, the sustain discharge period of the eighth subfield SF8 is set to about 50%. As such, when the sustain discharge period of the eighth subfield SF8 is reduced, the contrast ratio of the image displayed on the panel 60 is adjusted to be low.

Similarly, the contrast adjusting unit 62 may set the sustain discharge periods of the first and second subfields SF1 and SF2 to about 50% as shown in FIG. 8. As such, when the sustain discharge periods of the first and second subfields SF1 and SF2 are reduced, the contrast ratio of the image displayed on the panel 60 is adjusted to be high. That is, the contrast adjusting unit 62 adjusts the contrast of the image displayed on the panel 60 by adjusting the sustain period of at least one subfield SF.

The controller 58 generates a timing control signal using the N-stage signal input from the APL unit 56, and supplies the generated control signal to the address driving IC, the scan driving IC, and the sustain driving IC. At this time, the control unit 58 generates a timing control signal so that the number of discharges in the sustain period included in each subfield can be adjusted by the control of the contrast adjusting unit 62 and the luminance adjusting unit 64.

In addition, the control unit generates a timing control signal for controlling the number of sustain pulses or the width of the sustain pulses applied in the sustain period in order to further increase the gray scale expressing power represented by the sustain discharge.

9 is a diagram illustrating a first driving method of the plasma display panel according to the control unit of the present invention.

Referring to FIG. 9, the first driving method of the plasma display panel according to the present invention divides one frame into a plurality of subfields including one or more subfields, each subfield having a reset period, an address period, a sustain period, and an erase operation. Each is time-divided into periods. Each time-divided subfield is set to have a predetermined luminance weight.

First, in the first subfield having the lowest luminance weight, in the reset period, a setup / setdown pulse in the form of a ramp signal having a predetermined slope is supplied to the scan electrode Y to cause a reset discharge in the cells of the full screen. Since the wall discharge is uniformly accumulated in the cells of all screens by the reset discharge, the discharge characteristics are uniform.

In the address period, the data pulse data is supplied to the address electrode X, and the negative scan pulse Scan is sequentially supplied to the scan electrodes Y in synchronization with the data pulse data. At this time, the voltage of the negative scan pulse is preferably lower than the lowest voltage of the set-down pulse applied in the reset period. As the voltage difference between the scan pulse and the data pulse and the wall voltage generated during the reset period are added, an address discharge is generated in the cell to which the data pulse is applied.

In the sustain period, the sustain pulse SUS may be alternately supplied to the scan electrode Y or the sustain electrode Z. However, as illustrated, the scan electrode Y may be provided so that the gray scale may have a decimal value. Supply a sustain pulse only. Of course, the sustain pulse may be supplied only to the sustain electrode Z without being supplied to the scan electrode Y.

In the erasing period, when the sustain pulse SUS is supplied to only one of the scan electrodes Y and the sustain electrode Z in the sustain period, a ramp waveform is applied to the electrodes Y and Z that are not supplied with the sustain pulse. Erasure pulses are supplied.

Thereafter, the address period of the second subfield SF2 having the luminance weight higher than the first subfield is the same as the address period of the first subfield. In the sustain period, however, the sustain pulse SUS is alternately supplied to the scan electrode Y or the sustain electrode Z similarly to the first subfield. In the erase period, an erase pulse applied in the first subfield is supplied to the scan electrode (Y).

Thereafter, the address periods of the third, fourth, fifth, sixth, seventh and eighth subfields SF3, SF4, SF5, SF6, SF7 and SF8, in which the luminance weight is sequentially increased, are the same as the address period of the first subfield. Is done. In the sustain period, as in the second subfield, the sustain pulse SUS is alternately supplied to the scan electrode Y or the sustain electrode Z, and the erase period is also scanned in the scan electrode Y like the second subfield. The erase pulse is supplied.

As such, in the subfield SF1 which applies the sustain pulse to only one of the scan electrode Y and the sustain electrode Z in the subfield having the lowest luminance weight, the sustain pulse is alternately applied to the conventional scan electrode and the sustain electrode. The gray scale value smaller than the gray scale value according to the light appearing in the subfield SF3 to be applied is expressed, thereby improving image quality.

Of course, the sustain pulse may be applied to only one of the scan electrode and the sustain electrode during the sustain period regardless of the luminance weight of the subfield.

Therefore, the number of sustain pulses applied to any one of the scan electrode and the sustain electrode in one frame is different from the number of the sustain pulses applied to the other electrodes, so that a fine gray level can be expressed even in an image having a high gray level value.

10 is a view for explaining a second driving method of the plasma display panel according to the control unit of the present invention.

Referring to FIG. 10, the second driving method of the plasma display panel according to the present invention, like the first driving method, divides one frame into a plurality of subfields including one or more subfields. It is time-divided into an address period, a sustain period, and an erase period, respectively. Each time-divided subfield is set to have a predetermined luminance weight.

First, in the reset period of the first subfield SF1 having the lowest luminance weight, a setup / setdown pulse in the form of a ramp signal having a predetermined slope is supplied to the scan electrode Y to cause a reset discharge in the cells of the full screen. Since the wall discharge is uniformly accumulated in the cells of the entire screen by the reset discharge, the discharge characteristics are uniform.

In the address period, the data pulse data is supplied to the address electrode X, and the negative scan pulse Scan is sequentially supplied to the scan electrodes Y in synchronization with the data pulse data. As the voltage difference between the scan pulse and the data pulse and the wall voltage generated during the reset period are added, an address discharge is generated in the cell to which the data pulse is applied.

In the sustain period, the sustain pulse is not supplied to any one of the scan electrode Y or the sustain electrode Z. That is, the scan electrode Y and the sustain electrode Z are maintained at the ground level.

In the erase period, an erase pulse is supplied to the scan electrode (Y).

Thereafter, the address period of the second subfield SF2 having the luminance weight higher than the first subfield is the same as the address period of the first subfield. In the sustain period, however, the sustain pulse SUS may be alternately supplied to the scan electrode Y or the sustain electrode Z as in the first subfield. However, as illustrated, the scan electrode Y is preferably used. Alternatively, a sustain pulse is supplied only to one of the sustain electrodes Z. In the erasing period, when the sustain pulse SUS is supplied to only one of the scan electrode Y and the sustain electrode Z in the sustain period, the ramp waveform is applied to the electrodes Y and Z which are not supplied with the sustain pulse. An erase pulse such as is supplied.

Thereafter, the address periods of the third, fourth, fifth, sixth, seventh and eighth subfields SF3, SF4, SF5, SF6, SF7 and SF8, in which the luminance weight is sequentially increased, are the same as the address period of the first subfield. Is done. In the sustain period, the sustain pulse SUS is alternately supplied to the scan electrode Y or the sustain electrode Z.

In the erase period, an erase pulse is supplied to the scan electrode Y.

In the subfields SF1 and SF9 in which the sustain pulse is not applied to any one of the scan electrode Y and the sustain electrode Z in the subfield having the lowest luminance weight as described above, the scan electrode Y and the sustain are sustained in the sustain period. The gray scale value smaller than the gray scale value due to the light appearing in the subfield SF2 applying the sustain pulse to only one of the electrodes Z can be expressed.

That is, in the subfield having the lowest luminance weight among the plurality of subfields, the gray scale is expressed by the discharge generated in the address period, thereby representing a more detailed gray scale value.

11 illustrates a third driving method of the plasma display panel according to the control unit of the present invention.

Referring to FIG. 11, the third driving method of the plasma display panel according to the present invention, like the first driving method, divides one frame into a plurality of subfields including one or more subfields. It is time-divided into an address period, a sustain period, and an erase period, respectively. Each time-divided subfield is set to have a predetermined luminance weight.

First, in the reset period of the first subfield SF1 having the lowest luminance weight, a setup / setdown pulse in the form of a ramp signal having a predetermined slope is supplied to the scan electrode Y to cause a reset discharge in the cells of the full screen. Since the wall discharge is uniformly accumulated in the cells of all screens by the reset discharge, the discharge characteristics are uniform.

In the address period, the data pulse data is supplied to the address electrode X, and the negative scan pulse Scan is sequentially supplied to the scan electrodes Y in synchronization with the data pulse data. As the voltage difference between the scan pulse and the data pulse and the wall voltage generated during the reset period are added, an address discharge is generated in the cell to which the data pulse is applied.

In the sustain period, the sustain pulse SUS may be alternately supplied to the scan electrode Y or the sustain electrode Z. Preferably, as illustrated, the sustain pulse SUS is applied to the scan electrode Y. The width W1 is set to be narrower than the width of the second sustain pulse W2 applied in the sustain periods of the other subfields SF2, SF3, SF4, SF5, SF6, SF7, SF8. As such, the first sustain pulse smaller than the width of the second sustain pulse applied to the other subfield may be applied to only one of the scan electrode and the sustain electrode.

In the erasing period, when the sustain pulse SUS is supplied to only one of the scan electrodes Y and the sustain electrode Z in the sustain period, a ramp waveform is applied to the electrodes Y and Z that are not supplied with the sustain pulse. Erasure pulses are supplied.

Thereafter, the address period of the second subfield SF2 having the luminance weight higher than that of the first subfield is the same as the address period of the first subfield. In the sustain period, however, the sustain pulse SUS may be alternately supplied to the scan electrode Y or the sustain electrode Z as in the first subfield. However, as illustrated, the scan electrode Y is preferably used. Alternatively, a sustain pulse is supplied to only one of the sustain electrodes Z to generate sustain discharge.

In the erase period, as in the first subfield, when the sustain pulse SUS is supplied to only one of the scan electrode Y and the sustain electrode Z in the sustain period, the electrode Y, which is not relatively supplied with the sustain pulse, is supplied. Z) is supplied with an erase pulse such as a ramp waveform.

Thereafter, the address periods of the third, fourth, fifth, sixth, seventh and eighth subfields SF3, SF4, SF5, SF6, SF7 and SF8, in which the luminance weights are sequentially increased, are the same as the address period of the first subfield. Is done. In the sustain period, the sustain pulse SUS is alternately supplied to the scan electrode Y or the sustain electrode Z. FIG. At this time, the width W2 of the sustain pulse is the same as the width W2 of the sustain pulse which is generally supplied.

In the erase period, an erase pulse is supplied to the scan electrode Y.

As such, when the width of the first sustain pulse applied in the sustain period in the subfield having the lowest luminance weight is smaller than the width of the second sustain pulse applied in the sustain period of the subfield in which the remaining luminance weight is different, the first sustain pulse is further reduced. Detailed grayscale values are expressed. In this case, the first sustain pulse is applied to only one of the scan electrode Y and the sustain electrode Z to express a more detailed gray level value.

1 is a perspective view showing the structure of a three-electrode AC surface discharge type PDP having a discharge cell structure arranged in a matrix form according to the related art.

2 is a block diagram showing a driving apparatus of a conventional plasma display panel.

3 is a diagram illustrating a method of implementing image gradation of a conventional plasma display panel.

4 is a block diagram showing a driving apparatus of a plasma display panel according to the present invention;

5 is a block diagram showing a driving unit of the plasma display panel according to the present invention;

6 is a diagram illustrating a luminance adjusting method of a plasma display panel according to an exemplary embodiment of the present invention.

7 and 8 illustrate a contrast adjustment method of a plasma display panel according to an embodiment of the present invention.

9 is a view showing a first driving method of a plasma display panel according to the present invention;

10 is a view showing a second driving method of a plasma display panel according to the present invention;

11 is a view showing a third driving method of the plasma display panel according to the present invention;

Claims (17)

A plasma display device for receiving a digital video signal from the outside and expressing an image by dividing one frame into a plurality of subfields, A video scan converter for converting the digital video signal to a resolution of a plasma display panel; Regardless of the converted digital video signal inputted to the driver, the sustain discharge period of the plurality of subfields is adjusted to adjust the contrast and the brightness of the image, and the sustain of at least one subfield of the plurality of subfields is adjusted. Control unit to apply a sustain pulse to only one of the scan electrode and the sustain electrode during the discharge period Plasma display device comprising a.  The method of claim 1, And the driver controls the sustain discharge period of at least one subfield. The method of claim 1, And the driving unit adjusts sustain discharge periods of all subfields at the same ratio. The method of claim 1, The driving unit includes a first and second inverse gamma correction unit, a gain control unit, an error diffusion unit, an average image leveling unit, a contrast control unit, and a luminance control unit. The method of claim 1, And the number of sustain pulses applied to any one of the scan electrode and the sustain electrode in the one frame is greater than the number of the sustain pulses applied to the other electrodes. The method of claim 1, And the sustain pulse is applied only to any one of the scan electrode and the sustain electrode in the subfield having the smallest luminance weight among the plurality of subfields. A plasma display device for receiving a digital video signal from the outside and expressing an image by dividing one frame into a plurality of subfields, A video scan converter for converting the digital video signal to a resolution of a plasma display panel; And Regardless of the converted digital video signal inputted to the driver, the sustain discharge period of the plurality of subfields is adjusted to adjust the contrast and the brightness of the image, and the sustain of at least one subfield of the plurality of subfields is adjusted. And a control unit for preventing a sustain pulse from being applied to any of the scan electrode and the sustain electrode so that sustain discharge does not occur during the period. The method of claim 7, wherein And the driver adjusts the sustain discharge period of at least one subfield. The method of claim 7, wherein And the driving unit adjusts sustain discharge periods of all subfields at the same ratio. The method of claim 7, wherein The driving unit includes a first and second inverse gamma correction unit, a gain control unit, an error diffusion unit, an average image leveling unit, a contrast control unit, and a luminance control unit. The method of claim 7, wherein And the sustain pulse is not applied to any of the scan electrode and the sustain electrode in the subfield having the lowest luminance weight among the plurality of subfields. The method of claim 11, And the gray level is represented by the discharge generated in the address period in the subfield having the lowest luminance weight among the plurality of subfields. A plasma display device for receiving a digital video signal from the outside and expressing an image by dividing one frame into a plurality of subfields, A video scan converter for converting the digital video signal to a resolution of a plasma display panel; And Irrespective of the converted digital video signal inputted to the driver, the sustain discharge period of the plurality of subfields is adjusted to adjust the contrast and the brightness of the image, and the subfield having the lowest luminance weight among the plurality of subfields. And a control unit such that the width of the first sustain pulse applied to the scan electrode and the sustain electrode in the sustain discharge period is smaller than the width of the second sustain pulse applied to the sustain discharge period of another subfield. The method of claim 13, And the driver adjusts the sustain discharge period of at least one subfield. The method of claim 13, And the driver controls the sustain discharge periods of all subfields at the same ratio. The method of claim 13, The driving unit includes a first and second inverse gamma correction unit, a gain control unit, an error diffusion unit, an average image leveling unit, a contrast control unit, and a luminance control unit. The method of claim 13, The first sustain pulse is applied to only one of the scan electrode and the sustain electrode, the plasma display device.

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