WO2009057889A1

WO2009057889A1 - Plasma display apparatus

Info

Publication number: WO2009057889A1
Application number: PCT/KR2008/004988
Authority: WO
Inventors: Jeongpil Choi; Seongho Kang
Original assignee: Lg Electronics Inc.
Priority date: 2007-10-31
Filing date: 2008-08-26
Publication date: 2009-05-07
Also published as: KR20090044333A

Abstract

A plasma display apparatus displaying an image in a frame including a plurality of subfields is disclosed. The plasma display apparatus includes a video scan converter that converts a digital video signal received from the outside in conformity with a resolution of a plasma display panel, and a driver that controls sustain discharge periods of the plurality of subfields so as to control a contrast and a luminance of the image regardless of the converted digital video signal. The driver includes a waveform generation unit that supplies a sustain signal to one of a scan electrode and a sustain electrode during the sustain discharge period of at least one subfield of the plurality of subfields.

Description

Description PLASMA DISPLAY APPARATUS

Technical Field

[1] This invention relates to a plasma display appraratus.

Background Art

[2] A plasma display panel (PDP) displays images including characters and/or graphics by exciting phosphors by ultraviolet rays of 147 nm generated during a discharge of an inert gas mixture such as He-Xe mixture or Ne-Xe mixture.

[3] FIG. 1 is a perspective view showing a configuration of a related art three-electrode

AC surface discharge type PDP having discharge cells arranged in matrix format.

[4] As shown in FIG. 1, the three-electrode AC surface discharge type PDP includes a scan electrode 11 and a sustain electrode 12 on an upper substrate 10, and an address electrode 22 on a lower substrate 20. The scan electrode 11 and the sustain electrode 12 each include transparent electrodes 11a and 12a formed of a transparent material such as indium-tin-oxide (ITO) and metal bus electrodes 1 Ib and 12b for reducing a resistance of the scan electrode 11 and the sustain electrode 12. An upper dielectric layer 13a and a protection film 14 are laminated on the upper substrate 10 having the scan electrode 11 and the sustain electrode 12 formed thereon. Wall charges generated during a plasma discharge are accumulated on the upper dielectric layer 13 a. The protection film 14 prevents the upper dielectric layer 13a from being damaged by sputtering generated during the plasma discharge, and also increases the secondary electron emission efficiency. The protection film 14 is usually formed of oxide magnesium (MgO).

[5] A lower dielectric layer 13b and barrier ribs 21 are formed on the lower substrate 20 having the address electrode 22 formed thereon. A phosphor layer 23 is coated on the surface of the lower dielectric layer 13b and the barrier ribs 21. The address electrode 22 is disposed to intersect the scan electrode 11 and the sustain electrode 12. The barrier ribs 21 are positioned parallel to the address electrode 22 and prevent ultraviolet rays and visible light, which are produced during a discharge, from leaking to adjacent discharge cells. The phosphor layer 23 is excited by the ultraviolet rays generated during a plasma discharge to generate one of red (R), green (G) and blue (B) visible light. An inert gas mixture such as He-Xe mixture or Ne-Xe mixture is injected into the discharge cells partitioned by the barrier ribs 21 between the upper substrate 10 and the lower substrate 20.

[6] FIG. 2 is a block diagram showing a related art apparatus for driving a plasma display panel. As shown in FIG. 2, the related art driving apparatus includes a digital- to-analog converter 32, a video signal processing unit 34, a video scan converter (VSC) 36, and a PDP driver 40.

[7] The digital-to- analog converter 32 converts an input digital video signal into an analog video signal to supply the analog video signal to the video signal processing unit 34.

[8] A luminance control unit 34a and a contrast control unit 34b of the video signal processing unit 34 operate depending on a luminance control signal and a contrast control signal provided by a PDP user, namely, a PC mode or a AV mode, and thus the video signal processing unit 34 adjusts a voltage level and/or a gain of the analog video signal input by the digital-to-analog converter 32. Hence, a luminance and a contrast of an image displayed on the panel are adjusted.

[9] The video scan converter 36 converts the analog video signal input by the video signal processing unit 34 into a digital video signal suitable for a resolution of the plasma display panel to supply the digital video signal to the PDP driver 40. The PDP driver 40 corrects the digital signal input by the video scan converter 36 to supply the corrected digital signal to the plasma display panel. For example, the PDP driver 40 reassigns video data of the digital video signal to each subfield depending on the luminance and the contrast of the video signal processed by the video signal processing unit 34 and corrects the luminance and the contrast of the video signal to supply the corrected digital signal to the plasma display panel.

[10] The related art PDP driving apparatus converts the digital video signal input from the outside into the analog video signal and again converts the analog video signal into the digital video. Because the digital signal is converted into the analog video signal so as to control the luminance and the contrast of the video signal in a process for converting the digital signal-to-the analog video signal-to-the digital signal, the distortion and the damping of the video signal occur. Hence, the image quality of the plasma display panel is deteriorated.

[11] As shown in FIG. 3, the related art plasma display panel is driven in a state where one frame is divided several subfields having a different number of emission times. Each subfield is divided into a reset period for uniformly generating a discharge, an address period for selecting a discharge cell, and a sustain period for implementing a gray scale depending on the number of discharges.

[12] For example, if an image with 256 gray levels is to be displayed, a frame period (for example, 16.67 ms) corresponding to 1/60 sec is divided into 8 subfields SFl to SF8. Each of the eight subfields SFl to SF8 is subdivided into a reset period, an address period, and a sustain period. The duration of the reset period is equal to each other in all the subfields, and the duration of the address period is equal to each other in all the subfields. The sustain period increases in a ratio of 2ⁿ (where, n = 0, 1, 2, 3, 4, 5, 6, 7) in each subfield.

[13] As described above, the gray scale of the related art plasma display panel is represented by controlling the number of discharges generated during the sustain period of each subfield. To be more specific, the gray scale is represented depending on a weight value assigned to each subfield.

[14] For example, if a weight value of the first subfield SFl is set at the lowest value of 2°

, a data signal is supplied to the address electrodes and scan signals are sequentially supplied to the scan electrodes in synchronization with the data signal during an address period of the first subfield SFl. As a voltage difference between the data signal and the scan signal is added to a wall voltage inside the discharge cells, an address discharge occurs inside the discharge cells to which the data signals are supplied. During a sustain period of the first subfield SFl, a sustain signals corresponding to the weight value 2° are supplied alternately to the scan electrode and the sustain electrode. As a result, as the sustain signal is added to a wall voltage inside the discharge cells, a discharge occurs inside the discharge cells selected during the address period, thereby representing the gray scale. Disclosure of Invention Technical Problem

[15] However, the method for representing the gray scale of the related art PDP is problematic in that a gray level smaller than the weight value 2° (= 1) cannot be represented. That is, in the related art PDP, each subfield is set at a weight value of a natural number, and a combination of the subfields each having the weight value of the natural number is represented as a natural number. Accordingly, the method for representing the gray scale of the related art PDP cannot represent the gray scale having a decimal value, thereby having a restriction of an improvement in the image quality. Technical Solution

[16] a plasma display apparatus displaying an image in a frame including a plurality of subfields comprises a video scan converter that converts a digital video signal received from the outside in conformity with a resolution of a plasma display panel, and a driver that controls sustain discharge periods of the plurality of subfields so as to control a contrast and a luminance of the image regardless of the converted digital video signal, the driver including a waveform generation unit that supplies a sustain signal to one of a scan electrode and a sustain electrode during the sustain discharge period of at least one subfield of the plurality of subfields.

Advantageous Effects

[17] Accordingly, an exemplary embodiment provides a plasma display apparatus suitable for a digital signal processing capable of improving the image quality by finely rep- resenting a gray scale.

Brief Description of the Drawings

[18] FIG. 1 is a perspective view showing a configuration of a related art three-electrode

AC surface discharge type plasma display panel having discharge cells arranged in matrix format.

[19] FIG. 2 is a block diagram showing a related art apparatus for driving a plasma display panel.

[20] FIG. 3 illustrates a method for representing a gray scale of a related art plasma display panel.

[21] FIG. 4 shows a driving apparatus of a plasma display panel according to an exemplary embodiment of the invention.

[22] FIG. 5 is a block diagram showing a driver of the plasma display panel according to the exemplary embodiment of the invention.

[23] FIG. 6 illustrates a method for controlling a luminance of the plasma display panel.

[24] FIGs. 7 and 8 illustrate a method for controlling a contrast of the plasma display panel.

[25] FIG. 9 illustrates a first implementation of a method of driving the plasma display panel.

[26] FIG. 10 illustrates a second implementation of a method of driving the plasma display panel.

[27] FIG. 11 illustrates a third implementation of a method of driving the plasma display panel. Best Mode for Carrying Out the Invention

[28] FIG. 4 shows a driving apparatus of a plasma display panel (PDP) according to an exemplary embodiment of the invention.

[29] As shown in FIG. 4, the plasma display apparatus according to the exemplary embodiment of the invention includes a video scan converter 42 and a PDP driver 44. The video scan converter 42 receives a digital video signal from the outside and converts the digital video signal, namely, video data in conformity with a resolution of the plasma display panel to supply the converted digital video signal to the PDP driver 44.

[30] The PDP driver 44 processes the digital video signal in response to a control signal provided by a PDP user, for example, a control signal provided by a remote controller or a control panel. In this case, the PDP driver 44 controls a length of a sustain discharge period regardless of the digital video signal converted by the video scan converter 42, thereby controlling a luminance and a contrast of an image.

[31] Because the exemplary embodiment of the invention does not convert the digital video signal into an analog video signal so as to control the luminance and the contrast of the image, the distortion and the damping of the signal do not occur.

[32] The PDP driver 44, as shown in FIG. 5, includes a first inverse-gamma correction unit 46 A, a gain control unit 48, an error diffusion unit 50, a subfield mapping unit 52, a data aligning unit 54, a second inverse-gamma correction unit 46B, an average picture level (APL) unit 56, a waveform generation unit 58, a panel 60, a contrast control unit 62, and a luminance control unit 64.

[33] The first and second inverse-gamma correction unit 46A and 46B perform an inverse-gamma correction process on the gamma-corrected digital video signal to linearly change a luminance corresponding to a gray level of the digital video signal.

[34] The APL unit 56 receives the video data corrected by the second inverse-gamma correction unit 46B to generate an N-stage signal for adjusting the number of sustain signals. The gain control unit 48 amplifies the video signal corrected by the first inverse-gamma correction unit 46A according to effective gains to supply the amplified video signal to the error diffusion unit 50.

[35] The error diffusion unit 50 diffuses an error component of a discharge cell to adjacent discharge cells to finely control a luminance. The subfield mapping unit 52 reassigns the video data corrected by the error diffusion unit 50 to each subfield to supply the reassigned video data the to the data aligning unit 54.

[36] The data aligning unit 54 aligns the video signal capable of being supplied to the panel 60 to supply the aligned video signal to an address driving integrated circuit (IC) (not shown).

[37] The waveform generation unit 58 produces timing control signals by the N-stage signal generated by the APL unit 56, and supplies the timing control signals to the address driving IC, a scan driving IC, and a sustain driving IC of the panel 60.

[38] The contrast control unit 62 and the luminance control unit 64 control the number of discharges generated during a sustain period to control the contrast and the luminance of the image displayed on the panel.

[39] This luminance control unit 64 controls the number of discharges generated during the sustain periods in response to the control signal provided by the user's remote control. As an example, as shown in FIG. 6, a sustain discharge occurs during a time interval corresponding to one half of a sustain period of each of the subfields SFl to SF8, and does not occur during the remaining time interval. If the sustain discharge occurs during the time interval corresponding to one half of the sustain period, a luminance of an image displayed on the panel 60 is reduced to 50% of a luminance of a normal discharge.

[40] In other words, the luminance control unit 64 controls the luminance of the image displayed on the panel 60 by controlling the sustain periods of all the subfields in batch processing. [41] The contrast control unit 62 controls the contrast of the image displayed on the panel

60 by controlling a sustain discharge period of at least one subfield. As an example, as shown in FIG. 7, the sustain discharge period of the eighth subfield SF8 is set at 50% of the sustain period. If the sustain discharge period of the eighth subfield SF8 is reduced, a contrast ratio of the image displayed on panel 60 is reduced.

[42] In the same manner, as shown in FIG. 8, the contrast control unit 62 can set the sustain discharge periods of the first and second subfields SFl and SF2 at about 50% of the sustain period. If the sustain discharge periods of the first and second subfields SFl and SF2 is reduced, the contrast ratio of the image displayed on the panel 60 increases. In other words, the contrast control unit 62 controls the sustain period of at least one subfield, thereby controlling the contrast of the image displayed on panel 60.

[43] The waveform generation unit 58 produces timing control signals using the N-stage signal outputted from the APL unit 56 and supplies the timing control signals to the address drive IC, the scan drive IC, and the sustain drive IC. The waveform generation unit 58 generates the timing control signals capable of controlling the number of discharges generated during the sustain period of each subfield under the control of the contrast control unit 62 and the luminance control unit 64.

[44] The waveform generation unit 58 generates the timing control signals capable of controlling the number of sustain signals or the width of the sustain signal during the sustain period so as to improve the representability of the gray scale achieved by the sustain discharge.

[45] FIG. 9 illustrates a first implementation of a method of driving the plasma display panel.

[46] As shown in FIG. 9, in the first implementation of the method of driving the plasma display panel, one frame is divided several subfields having a different number of emission times. Each subfield is divided into a reset period, an address period, a sustain period, and an erase period. Each subfield has a predetermined weight value.

[47] During a reset period of a first subfield SFl having a lowest weight value, a set-up signal Ramp-up and a set-down signal Ramp-down each having a predetermined slope are supplied to the scan electrode Y to generate a reset discharge inside the discharge cells of the entire screen. The reset discharge allows wall charges to be uniformly accumulated on the discharge cells of the entire screen.

[48] During an address period, a data signal data is supplied to the address electrodes X, and scan signals Scan of a negative polarity are sequentially supplied to the scan electrodes Y in synchronization with the data signal data. As the voltage difference between the scan signal Scan and the data signal data is added to a wall voltage generated during the reset period, an address discharge occurs inside the discharge cells to which the data signals are applied. [49] During a sustain period, sustain signals sus may be alternately supplied to the scan electrodes Y and the sustain electrodes Z. However, as shown in FIG. 9, the sustain signals sus are preferably supplied to one of the scan electrode Y and the sustain electrode Z so as to represent a gray level having a decimal value.

[50] During an erase period, when the sustain signals sus are supplied to one of the scan electrode Y and the sustain electrode Z during the sustain period, an erase signal Ramp-ers is supplied to the electrode to which the sustain signal sus is not supplied.

[51] During an address period of a second subfield SF2 having a weight value larger than the weight value of the first subfield SFl, the same operation as the operation performed during the address period of the first subfield SFl is performed. During a sustain period, the sustain signals are alternately supplied to the scan electrodes Y and the sustain electrode Z. During the erase period, an erase signal is supplied to the scan electrodes Y.

[52] During an address period of each of third to eighth subfields SF3 to SF8 whose weight values sequentially increase in turn, the same operation as the operation performed during the address period of the first subfield SFl is performed. During a sustain period, the sustain signals are alternately supplied to the scan electrodes Y and the sustain electrode Z in the same manner as the second subfield SF2. During an erase period, the erase signal is supplied to the scan electrodes Y in the same manner as the second subfield SF2.

[53] As described above, in the first implementation of the driving method, because the sustain signal is applied to one of the scan electrode Y and the sustain electrode Z in the first subfield SFl having the lowest weight value, the first subfield SFl can represent a gray level smaller than a gray level of light emitted in the subfield in which the sustain signals are alternately applied to the scan electrodes and the sustain electrode.

[54] The sustain signal may be applied to one of the scan electrodes Y and the sustain electrode Z during the sustain period regardless of the weight value.

[55] Accordingly, in the first implementation of the driving method, because the number of sustain signals applied to the scan electrode is different from the number of sustain signals applied to the sustain electrode in one frame, a gray level of an image having a high gray level can be finely represented. Mode for the Invention

[56] FIG. 10 illustrates a second implementation of a method of driving the plasma display panel.

[57] As shown in FIG. 10, in the second implementation of the method of driving the plasma display panel, in the same manner as the first implementation, one frame is divided several subfields having a different number of emission times. Each subfield is divided into a reset period, an address period, a sustain period, and an erase period. Each subfield has a predetermined weight value.

[58] During a reset period of a first subfield SFl having a lowest weight value, a set-up signal Ramp-up and a set-down signal Ramp-down each having a predetermined slope are supplied to the scan electrode Y to generate a reset discharge inside the discharge cells of the entire screen. The reset discharge allows wall charges to be uniformly accumulated on the discharge cells of the entire screen.

[59] During an address period, a data signal data is supplied to the address electrodes X, and scan signals Scan of a negative polarity are sequentially supplied to the scan electrodes Y in synchronization with the data signal data. As the voltage difference between the scan signal Scan and the data signal data is added to a wall voltage generated during the reset period, an address discharge occurs inside the discharge cells to which the data signals are applied.

[60] During a sustain period, sustain signals may be alternately supplied to the scan electrodes Y and the sustain electrodes Z. However, as shown in FIG. 10, the sustain signals are not supplied to the scan electrode Y and the sustain electrode Z. In other words, the scan electrode Y and the sustain electrode Z are maintained at a ground level voltage.

[61] During an erase period, an erase signal Ramp-ers is supplied to the sustain electrode

Z.

[62] During an address period of a second subfield SF2 having a weight value larger than the weight value of the first subfield SFl, the same operation as the operation performed during the address period of the first subfield SFl is performed. During a sustain period, sustain signals sus may be alternately supplied to the scan electrodes Y and the sustain electrodes Z. However, as shown in FIG. 10, the sustain signals sus are preferably supplied to one of the scan electrode Y and the sustain electrode Z. During an erase period, when the sustain signals sus are supplied to one of the scan electrode Y and the sustain electrode Z during the sustain period, an erase signal is supplied to the electrode to which the sustain signal sus is not supplied.

[63] During an address period of each of third to eighth subfields SF3 to SF8 whose weight values sequentially increase in turn, the same operation as the operation performed during the address period of the first subfield SFl is performed. During a sustain period, the sustain signals are alternately supplied to the scan electrodes Y and the sustain electrode Z. During an erase period, an erase signal is supplied to the scan electrodes Y.

[64] As described above, in the second implementation of the driving method, because the sustain signal is not applied to the scan electrode Y and the sustain electrode Z in the first subfield SFl having the lowest weight value, the first subfield SFl can represent a gray level smaller than a gray level of light emitted in the subfield in which the sustain signals are applied to one of the scan electrodes and the sustain electrode during the sustain period.

[65] In other words, because the first subfield SFl having the lowest weight value represents a gray level using the discharge generated during the address period of the first subfield SFl, the gray level can be finely represented.

[66] FIG. 11 illustrates a third implementation of a method of driving the plasma display panel.

[67] As shown in FIG. 11, in the third implementation of the method of driving the plasma display panel, in the same manner as the first implementation, one frame is divided several subfields having a different number of emission times. Each subfield is divided into a reset period, an address period, a sustain period, and an erase period. Each subfield has a predetermined weight value.

[68] During a reset period of a first subfield SFl having a lowest weight value, a set-up signal Ramp-up and a set-down signal Ramp-down each having a predetermined slope are supplied to the scan electrode Y to generate a reset discharge inside the discharge cells of the entire screen. The reset discharge allows wall charges to be uniformly accumulated on the discharge cells of the entire screen.

[69] During an address period, a data signal data is supplied to the address electrodes X, and scan signals Scan of a negative polarity are sequentially supplied to the scan electrodes Y in synchronization with the data signal data. As the voltage difference between the scan signal Scan and the data signal data is added to a wall voltage generated during the reset period, an address discharge occurs inside the discharge cells to which the data signals are applied.

[70] During a sustain period, sustain signals sus may be alternately supplied to the scan electrodes Y and the sustain electrodes Z. However, as shown in FIG. 11, the sustain signals sus are supplied to one of the scan electrode Y and the sustain electrode Z. A width Wl of the sustain signal applied in the first subfield SFl is smaller than a width W2 of the sustain signal applied in the other subfields SF2 to SF8.

[71] During an erase period, when the sustain signals sus are supplied to one of the scan electrode Y and the sustain electrode Z during the sustain period, an erase signal Ramp-ers is supplied to the electrode to which the sustain signal sus is not supplied.

[72] During an address period of a second subfield SF2 having a weight value larger than the weight value of the first subfield SFl, the same operation as the operation performed during the address period of the first subfield SFl is performed. During a sustain period, sustain signals sus may be alternately supplied to the scan electrodes Y and the sustain electrodes Z. However, as shown in FIG. 11, the sustain signals are supplied to one of the scan electrode Y and the sustain electrode Z. During an erase period, when the sustain signals sus are supplied to one of the scan electrode Y and the sustain electrode Z during the sustain period, an erase signal is supplied to the electrode to which the sustain signal sus is supplied.

[73] During an address period of each of third to eighth subfields SF3 to SF8 whose weight values sequentially increase in turn, the same operation as the operation performed during the address period of the first subfield SFl is performed. During a sustain period, the sustain signals are alternately supplied to the scan electrodes Y and the sustain electrode Z. In this case, the width W2 of the sustain signal may be equal to a width of a generally supplied sustain signal. During an erase period, an erase signal is supplied to the scan electrodes Y.

[74] As described above, in the third implementation of the driving method, because the width Wl of the sustain signal applied during the sustain period of the first subfield SFl having the lowest weight value is smaller than the widths W2 of the sustain signals applied during the sustain periods of the other subfields each having the weight value larger than the weight value of the first subfield SFl, the first subfield SFl can finely represent the gray level. Furthermore, because the sustain signal is applied to one of the scan electrode and the sustain electrode during the sustain period of the first subfield SFl having the lowest weight value, the gray level can be represented finely.

[75] It will be apparent to those skilled in the art that various modifications and variations can be made in the embodiments of the invention without departing from the spirit or scope of the invention. Thus, it is intended that embodiments of the invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

[1] A plasma display apparatus displaying an image in a frame including a plurality of subfields comprising: a video scan converter that converts a digital video signal received from the outside in conformity with a resolution of a plasma display panel; and a driver that controls sustain discharge periods of the plurality of subfields so as to control a contrast and a luminance of the image regardless of the converted digital video signal, the driver including a waveform generation unit that supplies a sustain signal to one of a scan electrode and a sustain electrode during the sustain discharge period of at least one subfield of the plurality of subfields.

[2] The plasma display apparatus of claim 1, wherein the driver controls the sustain discharge period of at least one subfield.

[3] The plasma display apparatus of claim 1, wherein the driver controls the sustain discharge periods of all the subfields in an equal ratio.

[4] The plasma display apparatus of claim 1, wherein the driver includes: first and second inverse-gamma correction units that perform an inverse-gamma correction process on the digital video signal output from the video scan converter; a gain control unit that amplifies the digital video signal corrected by the first inverse-gamma correction unit according to effective gains; an error diffusion unit that calculates an error component of a discharge cell from the amplified digital video signal and diffuses the error component to adjacent discharge cells; an average picture level (APL) unit that controls the number of sustain signals according to the digital video signal output from the error diffusion unit; a contrast control unit that receives the digital video signal from the video scan converter and controls the sustain discharge period so as to adjust a contrast of the image; and a luminance control unit that receives the digital video signal from the video scan converter and controls the sustain discharge period so as to adjust a luminance of the image.

[5] The plasma display apparatus of claim 1, wherein the number of sustain signals applied to the scan electrode is different from the number of sustain signals applied to the sustain electrode in one frame.

[6] The plasma display apparatus of claim 1, wherein the waveform generation unit supplies the sustain signal to one of the scan electrode and the sustain electrode in a subfield having a lowest weight value among the plurality of the subfields.

[7] A plasma display apparatus displaying an image in a frame including a plurality of subfields comprising: a video scan converter that converts a digital video signal received from the outside in conformity with a resolution of a plasma display panel; and a driver that controls sustain discharge periods of the plurality of subfields so as to control a contrast and a luminance of the image regardless of the converted digital video signal, the driver including a waveform generation unit that does not supply a sustain signal to a scan electrode and a sustain electrode during a sustain period of at least one subfield of the plurality of subfields.

[8] The plasma display apparatus of claim 7, wherein the driver controls the sustain discharge period of at least one subfield.

[9] The plasma display apparatus of claim 7, wherein the driver controls the sustain discharge periods of all the subfields in an equal ratio.

[10] The plasma display apparatus of claim 7, wherein the driver includes: first and second inverse-gamma correction units that perform an inverse-gamma correction process on the digital video signal output from the video scan converter; a gain control unit that amplifies the digital video signal corrected by the first inverse-gamma correction unit according to effective gains; an error diffusion unit that calculates an error component of a discharge cell from the amplified digital video signal and diffuses the error component to adjacent discharge cells; an average picture level (APL) unit that controls the number of sustain signals according to the digital video signal output from the error diffusion unit; a contrast control unit that receives the digital video signal from the video scan converter and controls the sustain discharge period so as to adjust a contrast of the image; and a luminance control unit that receives the digital video signal from the video scan converter and controls he sustain discharge period so as to adjust a luminance of the image.

[11] The plasma display apparatus of claim 7, wherein the waveform generation unit does not supply the sustain signal to the scan electrode and the sustain electrode in a subfield having a lowest weight value among the plurality of the subfields.

[12] The plasma display apparatus of claim 11, wherein a gray scale is represented using a discharge generated during an address period of the subfield having the lowest weight value.

[13] A plasma display apparatus displaying an image in a frame including a plurality of subfields comprising: a video scan converter that converts a digital video signal received from the outside in conformity with a resolution of a plasma display panel; and a driver that controls sustain discharge periods of the plurality of subfields so as to control a contrast and a luminance of the image regardless of the converted digital video signal, the driver including a waveform generation unit that allows a width of a first sustain signal applied to a scan electrode and a sustain electrode during a sustain discharge period of a subfield having a lowest weight value among the plurality of the subfields to be smaller than a width of a second sustain signal applied to the scan electrode and the sustain electrode during sustain discharge periods of the other subfields.

[14] The plasma display apparatus of claim 13, wherein the driver controls the sustain discharge period of at least one subfield.

[15] The plasma display apparatus of claim 13, wherein the driver controls the sustain discharge periods of all the subfields in an equal ratio.

[16] The plasma display apparatus of claim 13, wherein the driver includes: first and second inverse-gamma correction units that perform an inverse-gamma correction process on the digital video signal output from the video scan converter; a gain control unit that amplifies the digital video signal corrected by the first inverse-gamma correction unit according to effective gains; an error diffusion unit that calculates an error component of a discharge cell from the amplified digital video signal and diffuses the error component to adjacent discharge cells; an average picture level (APL) unit that controls the number of sustain signals according to the digital video signal output from the error diffusion unit; a contrast control unit that receives the digital video signal from the video scan converter and controls the sustain discharge period so as to adjust a contrast of the image; and a luminance control unit that receives the digital video signal from the video scan converter and controls he sustain discharge period so as to adjust a luminance of the image.

[17] The plasma display apparatus of claim 13, wherein the first sustain signal is applied to one of the scan electrode and the sustain electrode.