KR20080047772A - Plasma display and driving method thereof - Google Patents

Abstract

A plasma display apparatus and a driving method thereof are provided to prevent low discharge by executing a brightness correction period for equalizing the number of sustain discharges between respective groups. A plasma display apparatus includes a plasma display panel(100), a controller(200), a temperature detector(600), and drivers(300,400,500). The plasma display panel includes first and second electrodes, third electrodes across the first and second electrodes, and plural discharge cells formed by the first to third electrodes. The controller divides a frame into plural sub-fields and plural first electrodes into plural groups including first and second groups in a first sub-field of the plural sub-fields. The temperature detector detects the temperature of the plasma display panel. The drivers discharge illumination cells among discharge cells of the first group during a first period of the first sub-field, discharge illumination cells of the first and second groups by selecting illumination cells among the discharge cells of the second group during a second period, discharge the illumination cells of the second group as much as discharged numbers of the illumination cells of the first group during a third period of the first sub-field, and executes the third period during a part of the second period according to the detected temperature.

Description

Plasma display device and driving method thereof {PLASMA DISPLAY AND DRIVING METHOD THEREOF}

1 is a schematic plan view of a plasma display device according to an exemplary embodiment of the present invention.

2 is a diagram illustrating a method of driving a plasma display device according to a first embodiment of the present invention.

3 is a view illustrating a driving waveform of a specific plasma display device of the driving method shown in FIG. 2.

4 is a diagram illustrating a method of driving a plasma display device according to a second embodiment of the present invention.

FIG. 5 is a view illustrating a driving waveform of a specific plasma display device of the driving method shown in FIG. 4.

6 is a diagram illustrating an operation of the controller illustrated in FIG. 1.

The present invention relates to a plasma display device and a driving method thereof.

Plasma display devices are flat display devices that display characters or images using plasma generated by gas discharge, and dozens to millions or more of pixels are arranged in a matrix form according to their size.

In the plasma display device, one field (1TV field) is divided into a plurality of subfields having respective weights and driven, and the gray level is displayed by a combination of the weights of the subfields in which the display operation occurs among the plurality of subfields. Each subfield includes a reset period, an address period, and a sustain period. The reset period is a period for initializing the state of the discharge cells in order to stably perform the next address discharge, and the address period is a period for selecting discharge cells to emit light and discharge cells not to emit light among the plurality of discharge cells. The sustain period is a period in which sustain discharge is performed on the discharge cells selected in the address period in order to actually display an image.

At this time, there is a method of performing the sustain discharge operation on all the discharge cells after completing the addressing operation for all the discharge cells in each subfield, that is, a method of temporally separating the address period and the sustain period. This is generally called an ADS (Address Display Period Separation) method. This ADS method can be easily implemented, but since addressing operations are sequentially performed on all discharge cells, address discharge may not occur well due to a lack of priming particles in the discharge cells in the discharge cells addressed later in time. As a result, in the subsequent sustain period, sustain discharge may be unstable and low discharge may occur.

In the plasma display device, discharge characteristics vary according to temperature, and at high temperatures, the probability of such low discharge is increased.

SUMMARY OF THE INVENTION The present invention provides a plasma display device and a driving method thereof in which sustain discharge is stably generated.

According to a feature of the present invention, in a plasma display device including a plurality of first electrodes and a plurality of second electrodes, one frame is divided into a plurality of subfields including a first subfield, and the plurality of subfields are included in the first subfield. Provided is a method of driving a first electrode of dividing into a plurality of groups including a first group and a second group. The driving method may include sensing a temperature of the plasma display device, selecting a light emitting cell among discharge cells of the first group during a first address period in the first subfield, and generating the first group during a first organic period. Sustaining and discharging the light emitting cells of the first subfield, selecting the light emitting cells of the second group of discharge cells during the second address period of the first subfield, and generating the first and second light emitting cells during the second sustain period of the first subfield. Sustain-discharging the light-emitting cells of the second group, the number of times corresponding to the number of times the light-emitting cells of the first group are discharged in the first sustain period during the third sustain period of the first subfield. Sustain-discharging the light emitting cells, wherein the first and second groups are discharged to satisfy the assigned number of sustain discharges corresponding to the weight of the first subfield during the fourth sustain period. Including the step of maintaining the discharge in addition to the light emitting cells, and wherein the sensed temperature is detected when the reference temperature or more, followed by the second sustain period and the fourth driven in a sustain period and the third sustain period in order.

According to another feature of the present invention, a plasma display device including a plasma display panel, a controller, a temperature sensor, and a driver is provided. The plasma display panel includes a plurality of first electrodes and a plurality of third electrodes formed in a direction crossing the second electrode, and the plurality of discharge cells are formed by the plurality of first to third electrodes. Is formed. The controller divides one frame into a plurality of subfields, and divides the plurality of first electrodes into a plurality of groups including a first group and a second group in a first subfield of the plurality of subfields. The temperature detector detects a temperature of the plasma display panel. If the sensing temperature sensed by the temperature sensing unit is equal to or higher than a reference temperature, the driving unit selects and discharges light emitting cells of the first group of discharge cells during the first period of the first subfield, and maintains and discharges the light emitting cells during the second period. The light emitting cells of the two groups of discharge cells are selected to sustain discharge the light emitting cells of the first group and the second group, and the light emitting cells of the first group are discharged in the first period during the third period of the first subfield. And discharging the light emitting cells of the second group by a predetermined number of times, and when the sensing temperature is lower than a reference temperature, during the period of a part of the second period of sustain discharge of the light emitting cells of the first group and the second group, the third time period. Perform the period.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification. In addition, when a part of the specification is to "form" a certain component, this means that it may further include other components, without excluding other components unless specifically stated otherwise.

In addition, the wall charge referred to throughout the specification refers to a charge formed close to each electrode on the wall (eg, the dielectric layer) of the cell. And the wall charge is not actually in contact with the electrode itself, but is described here as "formed", "accumulated" or "stacked" on the electrode. In addition, the wall voltage refers to the potential difference formed in the wall of the cell by the wall charge.

1 is a schematic plan view of a plasma display device according to an exemplary embodiment of the present invention.

As shown in FIG. 1, a plasma display device according to an exemplary embodiment includes a plasma display panel 100, a controller 200, an address electrode driver 300, a scan electrode driver 400, and a sustain electrode driver 500. Include.

The plasma display panel 100 includes a plurality of address electrodes A1 to Am extending in the column direction, and a plurality of sustain electrodes X1 to Xn and scan electrodes Y1 to Yn extending in pairs in the row direction. Include. The sustain electrodes X1 to Xn are formed corresponding to the scan electrodes Y1 to Yn, and the display electrodes X1 to Xn and the scan electrodes Y1 to Yn perform display operations for displaying images in the sustain period. Perform. The address electrodes A1 to Am are disposed to be orthogonal to the sustain electrodes X1 to Xn and the scan electrodes Y1 to Yn. At this time, the discharge space at the intersection of the address electrodes A1 to Am, the scan electrodes Y1 to Yn, and the sustain electrodes X1 to Xn forms the cell 12. The structure of the plasma display panel 100 is an example, and a panel having another structure to which the driving method described below may be applied may also be applied to the present invention.

The controller 200 receives an image signal from the outside and outputs an address electrode driving control signal, a sustain electrode driving control signal, and a scan electrode driving control signal. The controller 200 divides and drives one frame into a plurality of subfields. Each subfield consists of a reset period, an address period, and a sustain period.

The address driver 300 receives an address electrode driving control signal from the controller 200 and applies a display data signal for selecting a discharge cell to be displayed to each address electrode.

The scan electrode driver 400 receives a scan electrode driving control signal from the controller 200 and applies a driving voltage to the scan electrode.

The sustain electrode driver 500 receives the sustain electrode driving control signal from the controller 200 and applies a driving voltage to the sustain electrode.

The temperature detector 600 detects the temperature of the plasma display panel 100 and transmits the temperature to the controller 200.

Hereinafter, a driving method and a driving waveform of the plasma display device according to the first embodiment of the present invention will be described with reference to FIGS. 2 and 3.

2 is a diagram illustrating a method of driving a plasma display device according to an exemplary embodiment of the present invention.

As shown in FIG. 2, in the driving method according to an exemplary embodiment of the present invention, one frame is driven by dividing a plurality of subfields, and each subfield is a reset period, an address / sustain mixing period T1, and a luminance correction period T3. ) And the joint maintenance period (T2). In addition, it is assumed that the plurality of scan electrodes Y1 to Yn are divided into a plurality of groups by tying the plurality of scan electrodes Y1 to Yn in a physical arrangement order. Here, the first group is called a first group G1 and the second group is called a second group G2. On the other hand, the plurality of scan electrodes Y1 to Yn can be grouped in an irregular manner as necessary.

The reset period applies a reset waveform to all the scan electrodes Y1 to Yn to erase the wall charges formed by the previous sustain discharge and to set up the wall charges to stably perform the next address discharge. do. The address / sustain mixing period T1 includes an address period A and a sustain period S and sequentially addresses all the pixels in each group and performs sustain discharge in the middle of the address. That is, the address / sustain mixing period T1 is a period in which the address period A and the sustain period S are mixed in time. The luminance correction period T3 is a period in which additional sustain discharge is selectively performed to correct luminance of all pixels of the panel so that the gradations of all the pixels of the panel match each other. The common sustain period T2 is a period in which sustain discharge is commonly performed for a predetermined period of time for all the pixels.

More specifically, in the reset period, the discharge cells of all the groups G1 to Gn are initialized and set to the non-discharge cell state. Meanwhile, the reset operation may be performed for each group by providing a reset period before the address period A in the address / sustain mixing period T1 without simultaneously initializing the discharge cells of all the groups G1 to Gn in the reset period.

In the next address / sustain mixing period T1, an address operation is performed on each scan electrode in the first group G1, and then a sustain discharge pulse is applied to the scan electrodes of the first group G1 to cause sustain discharge. Then, after performing an address operation on each scan electrode in the second group G2, a sustain discharge pulse is applied by applying a sustain discharge pulse to the scan electrodes of the second group G2. That is, when performing addressing and sustain discharge on each scan electrode of the first group G1, each scan electrode of the second group G2 has a rest period. In this way, sustain discharge is caused to the scan electrodes of the last group Gn. In addition, while the sustain discharge is performed with respect to any one group of pixels, the sustain discharge is performed with respect to the other group of pixels that are previously addressed.

In the luminance correction period T3, the length of the sustain period for each group is different in the address / sustain mixing period T1, so that the sustain discharge is selectively performed with an additional sustain period for each group so that all pixels have the same brightness. The luminance of the pixels of each group is corrected. Specifically, the luminance of the pixels of the first group G1 is determined by the sum of the respective weights in the sustain period S of the address period T1, and the pixels of the first group G1 are the luminance correction period. It has the highest luminance at the time point T3 starts. In order to have the luminance of the pixels of the first group G1 also have a sustain period, the pixels of the other group may perform the sustain discharge. In this way, all the pixels of the panel have the same luminance.

Subsequently, in the common sustain period T2, sustain discharge pulses are commonly applied to the scan electrodes Y in all groups to cause sustain discharge. In this way, it is possible to have a gradation degree assigned to each subfield. If the gradation level allocated to the corresponding subfield is satisfied by the following luminance correction period T2, the common sustain period T2 may be omitted.

When the sustain discharge in the common sustain period T2 ends, the reset period of the next subfield starts again.

3 is a view illustrating a driving waveform of a specific plasma display device of the driving method shown in FIG. 2. In FIG. 3, only the first group G1 and the second group G2 are illustrated in the plurality of scan electrode groups, and the driving waveforms applied to the A electrode are not illustrated. The description of the driving waveform applied to the A electrode is also omitted.

As shown in FIG. 3, in the reset period R, while the reference voltage (0 V in FIG. 3) is applied to the X electrode, the voltages of the Y electrodes of the first and second groups G1 and G2 are set at the voltage Vs. Incrementally increase to Vset voltage. Then, a weak reset discharge occurs between the Y electrode and the X electrode while the voltage of the Y electrode is increased, and wall charges are formed in the discharge cells of the first and second groups G1 and G2. Subsequently, with the Vs voltage applied to the X electrode, the voltages of the Y electrodes of the first and second groups G ₁ and G ₂ are gradually decreased from the Vs voltage to the Vnf voltage. Then, while a weak reset discharge occurs between the Y electrode and the X electrode while the voltage of the Y electrode decreases, the wall charges formed in the discharge cells of the first and second groups G1 and G2 are erased and initialized to the non-light emitting cell. . In general, the magnitude of the voltage (Vnf-Vs) is set near the discharge start voltage between the Y electrode and the X electrode. As a result, the wall voltage between the Y electrode and the X electrode becomes almost 0 V, thereby preventing the non-light emitting cell in which the address discharge has not occurred in the address period from being misdischarged in the sustain period.

In the address period AG1 of the address / sustain mixing period T1, a Ve voltage is applied to the X electrodes of the first and second groups G1 and G2, and a VscH voltage is applied to the Y electrode of the second group G2. In this state, scan pulses of the VscL voltage are sequentially applied to the plurality of Y electrodes of the first group G1. At this time, an address pulse (not shown) having a positive voltage is applied to the A electrode of the light emitting discharge cell among the discharge cells formed by the Y electrode to which the scan pulse is applied. Then, address discharge occurs in the discharge cells to which the VscL voltage of the scan pulse and the positive voltage of the address pulse are applied, and wall charges are formed on the X electrode and the Y electrode to form a light emitting cell. The Y electrode to which the scan pulse is not applied applies a VscH voltage higher than the VscL voltage, and a reference voltage is applied to the A electrode to which the address pulse is not applied although not shown.

In the sustain period S11, the sustain discharge pulse of the voltage Vs is applied to the Y electrodes of the first and second groups G1 and G2 and the voltage of 0 V is applied to the X electrodes to sustain discharge the light emitting cells. At this time, in the sustain period S11, a minimum sustain discharge, for example, is set such that only one or two sustain discharges occur. In FIG. 3, one sustain discharge pulse is applied to the Y electrodes of the first and second groups G1 and G2. At this time, since only the cells in which the address discharge has occurred in the address period AG1 of the first group G1 become light emitting cells, only two sustain discharges occur in the cells in which the address discharge has occurred in the address period AG1 of the first group G1. .

In the next address period AG2, the second group G2 is applied while the Vs voltage is applied to the X electrodes of the first and second groups G1 and G2, and the VscH voltage is applied to the Y electrodes of the first group G1. Scan pulses of the VscL voltage are sequentially applied to the plurality of Y electrodes of the plurality of Y electrodes, and an address pulse having a positive voltage is applied to the A electrodes of the discharge cells to emit light among the discharge cells of the first group G2. Then, address discharge occurs in the discharge cells to which the VscL voltage of the scan pulse and the positive voltage of the address pulse are applied, and the cells in the non-light emitting state are address discharged and set as light emitting cells.

In the sustain periods S12 and S21, a reference voltage is applied to the X electrodes of the first and second groups G1 and G2, and a sustain discharge pulse of the Vs voltage is applied to the Y electrodes of the first and second groups G1 and G2. Apply. At this time, since both wall charges are formed in the light emitting cells of the first and second groups G1 and G2, sustain discharge occurs simultaneously in the light emitting cells of the first and second groups G1 and G2. At this time, the second sustain period S12 of the first group G1 and the first sustain period S21 of the second group G2 are simultaneously performed. In this manner, an address period and a sustain period are performed for each group of subfields.

The luminance correction period T3 is a period for equalizing the number of sustain discharges of the first and second groups G1 and G2. In the luminance correction period T3, the sustain discharge pulse of the Vs voltage is applied to the X electrodes of the first and second groups G1 and G2, and the Vs1 voltage lower than the Vs voltage is applied to the Y electrode of the first group G1. A 0V voltage is applied to the Y electrode of the second group G2. At this time, the voltage Vs1 is a voltage such that sustain discharge does not occur between the Y electrode and the X electrode of the first group G1. Then, discharge does not occur in the discharge cells of the first group G1, but discharge occurs in the discharge cells of the second group G2. Then, a 0 V voltage is applied to the X electrode, and a sustain discharge pulse of the Vs voltage is applied to the Y electrodes of the first and second groups G1 and G2. Then, no discharge occurs in the discharge cells of the first group G1, but discharge occurs in the discharge cells of the second group G2. In this way, a total of two sustain discharges are further performed in the discharge cells of the second group G2, so that the number of sustain discharges in the first and second groups G1 and G2 is the same. That is, the number of times the sustain discharge occurs in the luminance correction period T3 is set to be equal to the number of times the sustain discharge occurs in the light emitting cells of the first group G1 in the sustain period S11. As a result, sustain discharge occurs in the discharge cells of the first and second groups G1 and G2 in one subfield, so that all pixels of the panel may have the same luminance.

Next, in the common sustain period T2, sustain discharge pulses of the voltage Vs are applied to the Y electrodes and the X electrodes of the first and second groups G1 and G2 in opposite phases, respectively, to thereby first and second groups G1. , The discharge cells of G2) are further sustained discharged. The common sustain period T2 is a period driven only when the total sustain discharge pulses allocated corresponding to the weights of the first subfields are not satisfied. More specifically, when the sustain discharge pulse applied to the Y electrode of the first group G1 in the address / sustain mixing period T1 is smaller than the total sustain discharge pulse allocated to the first subfield, the difference corresponds to the difference. The number of sustain discharge pulses is driven in the common sustain period T2.

As described above, according to the exemplary embodiment of the present invention, the plurality of scan electrodes are driven by dividing the plurality of groups, and the sustain period is performed between the address periods of each group, so that the wall charges are lost toward the second half of the address period, resulting in low discharge. You can prevent it. In addition, by performing the luminance correction period in which the number of sustain discharges between the groups is the same in one subfield, all the pixels of the plasma display panel can have the same luminance.

In general, the discharge characteristics of the plasma display panel 100 vary with temperature. The movement of electrons in the discharge space at a high temperature becomes active, and a large number of negative wall charges are formed on the Y electrode by the sustain discharge between the X electrode and the Y electrode in the sustain periods S12 and S21. At this time, when a low voltage such as Vs1 is applied to the Y electrode of the first group G1 in the luminance correction period T3, the X electrode and the low voltage difference between the X electrode and the Y electrode of the first group G1 are applied. The sustain discharge is generated between the Y electrodes of the first group G1. As a result, the sustain discharge is unstable in the common sustain period T2 caused by the loss of the negative wall charges formed on the Y electrode of the first group G1. Hereinafter, a driving method and a driving waveform of the plasma display device for stably generating sustain discharge at high temperature will be described with reference to FIGS. 4 and 5.

4 is a diagram illustrating a method of driving a plasma display device according to a second embodiment of the present invention, and FIG. 5 is a diagram illustrating a driving waveform of a specific plasma display device of the driving method shown in FIG. 4.

4 and 5, in the second embodiment of the present invention, the driving order of the common sustain period T2 and the luminance correction period T3 is changed in the first embodiment of the present invention. Same as the first embodiment.

In the driving method according to the second exemplary embodiment of the present invention, the common sustain period T2 is driven after the address / sustain mixing period T1, and the luminance correction period T3 is driven after the common sustain period T2. Then, the loss of the negative wall charges to the Y electrodes of the first group G1 in the luminance correction period T3 does not affect the common sustain period T2, thereby preventing unstable discharge from occurring at high temperatures. have. In order to stably generate sustain discharge at such a high temperature, the controller 200 shown in FIG. 1 operates as follows.

6 is a diagram illustrating an operation of the controller illustrated in FIG. 1.

As shown in FIG. 6, the controller 200 receives the temperature of the plasma display panel 100 sensed by the temperature sensor 600 (S610) and compares the detected temperature with a set reference temperature (S620). In this case, the reference temperature is a temperature at which discharge occurs between the Y electrode and the X electrode of the first group G1 when the voltage Vs1 is applied to the Y electrode of the first group G1 and the voltage Vs is applied to the X electrode.

If the detected temperature is lower than the reference temperature, the controller 200 controls the control signal 300 of each electrode to drive the control signal in order of the luminance / correction period T3 and the common sustain period T2 following the address / sustain mixing period T1. , 400, 500) (S640). In this case, the sustain discharge occurs stably by causing sustain discharge in common after the luminance between the first and second groups G1 and G2 is corrected.

In addition, when the sensing temperature is equal to or higher than the reference temperature, the controller 200 may control the control signal to drive the control signal so as to be driven in the order of the common sustain period T2 and the luminance correction period T3 following the address / sustain mixing period T1. 300, 400, 500) (S630). In this case, negative wall charges are lost to the Y electrodes of the first group G1 in the luminance correction period T3 at a high temperature, thereby preventing the sustain discharge from becoming unstable in the common sustain period T2.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

As described above, in the embodiment of the present invention, the plurality of scan electrodes are driven by dividing into a plurality of groups, and the address period is performed between the sustain periods of each group, so that the wall charges are lost toward the second half of the address period, resulting in low discharge. This can be prevented from happening.

In addition, in the case of high temperature, after performing the sustain discharge of all the groups in one subfield, the luminance correction period is made to equalize the number of sustain discharges between the groups. You can prevent it.

Claims (10)

In a plasma display device including a plurality of first electrodes and a plurality of second electrodes, one frame is divided into a plurality of subfields including a first subfield, and the plurality of first electrodes are divided into a first subfield in the first subfield. In the driving method divided into a plurality of groups including a group and a second group, Sensing a temperature of the plasma display device; Selecting a light emitting cell among the discharge cells of the first group during the first address period in the first subfield, and sustaining and discharging the light emitting cells of the first group during the first organic period; Selecting a light emitting cell among the discharge cells of the second group during the second address period of the first subfield; Sustain discharge of the light emitting cells of the first and second groups during the second sustain period of the first subfield; Sustain-discharging the light-emitting cells of the second group by the number of times corresponding to the number of times the light-emitting cells of the first group are discharged in the first sustain period during the third sustain period of the first subfield; and And further performing sustain discharge on the light emitting cells of the first and second groups so as to satisfy the number of sustain discharges allocated corresponding to the weight of the first subfield during the fourth sustain period after the third sustain period. , And driving the fourth sustain period and the third sustain period after the second sustain period, when the sensed detected temperature is equal to or greater than a reference temperature. The method of claim 1, And in the first sustain period, when the light emitting cells of the first group are sustain discharged, the light emitting cells of the second group are not sustain discharged. The method of claim 1, And in the third sustain period, when the second group of light emitting cells is sustain discharged, the light emitting cells of the first group are not sustain discharged. The method of claim 1, And the number of times that the first group of light emitting cells is sustain discharged in the first, second and fourth sustain periods satisfies the number of sustain discharges allocated corresponding to the weights of the first subfields. The method of claim 1, And a number of sustain discharges of the second group of light emitting cells in the second, third, and fourth sustain periods satisfies the number of sustain discharges allocated corresponding to the weights of the first subfields. The method of claim 1, When the number of sustain discharges of the first group of light emitting cells in the first and second sustain periods satisfies the number of sustain discharges allocated corresponding to the weight of the first subfield, the fourth sustain period is a rest period. A method of driving a plasma display device. A plasma display including a plurality of first electrodes and a plurality of third electrodes formed in a direction crossing the second electrode, wherein the plurality of discharge cells are formed by the plurality of first to third electrodes panel, A controller which divides one frame into a plurality of subfields and divides the plurality of first electrodes into a plurality of groups including a first group and a second group in a first subfield of the plurality of subfields; A temperature sensing unit sensing a temperature of the plasma display panel; When the sensing temperature sensed by the temperature sensing unit is equal to or greater than a reference temperature, the light emitting cells of the first group of discharge cells are selected and sustained discharged during the first period of the first subfield, and the second group is discharged during the second period. The number of times the light emitting cells of the first group and the second group are sustained and discharged by selecting the light emitting cells among the discharge cells of, and the light emitting cells of the first group are discharged in the first period during the third period of the first subfield. Discharge the light emitting cells of the second group by And a driver configured to perform the third period during a portion of the second period during which the first group and the second group of light emitting cells are sustained and discharged when the sensing temperature is less than the reference temperature. The method of claim 7, wherein The driving unit, And sustain discharge of the light emitting cells of the first group in the first and second periods by the number of sustain discharges allocated corresponding to the weight of the first subfield. The method of claim 7, wherein The driving unit, And sustain discharge the light emitting cells of the second group in the second and third periods by the number of sustain discharges allocated corresponding to the weights of the first subfields. The method of claim 7, wherein The driving unit, In the first period in which the light emitting cells of the first group of discharge cells are selected, the light emitting cells of the second group of discharge cells are not selected. And a light emitting cell of the first group of discharge cells is not selected in the second period of the light emitting cell of the second group of discharge cells.

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