KR20080043675A - Plasma display apparatus - Google Patents

Abstract

A plasma display device is provided to prevent electrical shock to a driving unit of the display device by adjusting rotating speed of a dither mask based on APL(Average Power Level). A plasma display device includes a PDP(Plasma Display Panel,100) and a driving unit(110). The PDP displays an image. The PDP includes first and second electrodes which are parallel to each other. Third electrodes of the PDP cross the first and second electrodes. The driving unit represents grayscale of an image using a dither mask. When the APL of the image data is a first level, the driving unit rotates the dither mask at a first speed. When the APL of the image data is a second level, the driving unit rotates the dither mask at a second speed which is smaller than the first speed.

Description

Plasma Display Apparatus {Plasma Display Apparatus}

1 is a view for explaining an example of the configuration of a plasma display device according to an embodiment of the present invention.

2 is a view for explaining an example of the structure of a plasma display panel that can be included in the plasma display device according to an embodiment of the present invention.

3 is a view for explaining an example where at least one of the first electrode or the second electrode is a plurality of layers;

4 is a view for explaining an example in the case where at least one of the first electrode or the second electrode is a single layer;

FIG. 5 is a diagram for describing an image frame for implementing gray levels of an image in a plasma display device according to an embodiment of the present invention. FIG.

6 is a view for explaining an example of the operation of the plasma display device according to an embodiment of the present invention.

7A to 7B are views for explaining another form of the rising ramp signal or the second falling ramp signal.

8 is a diagram for explaining an average power level.

9 is a view for explaining an example of the configuration of a drive unit for halftone correction.

10 is a diagram for explaining an example of a halftone correction method using a dither mask.

11 is a diagram for explaining rotation of a dither mask.

12 is a view for explaining an example of a method of adjusting the rotational speed of the dither mask in relation to the average power level.

13A to 13B are views for explaining another example of a method of adjusting the rotational speed of the dither mask in relation to the average power level.

14 is a view for explaining another example of a method of adjusting the rotational speed of the dither mask in relation to the average power level.

<Description of the numbers for the main parts of the drawings>

100: plasma display panel 110: driver

The present invention relates to a plasma display device (Plasma Display Apparatus).

The plasma display apparatus may include a plasma display panel having electrodes formed thereon, and a driving unit supplying driving signals to the electrodes of the plasma display panel.

In general, a phosphor layer is formed in a discharge cell (Cell) partitioned by a partition, and a plurality of electrodes are formed in the plasma display panel.

The driver supplies a driving signal to the discharge cell through the electrode.

Then, the discharge is generated by the drive signal supplied in the discharge cell. Here, when discharged by a drive signal in the discharge cell, the discharge gas filled in the discharge cell generates light such as ultraviolet rays, and the light such as ultraviolet light emits phosphors formed in the discharge cell. Generates visible light The visible light displays an image on the screen of the plasma display panel.

One embodiment of the present invention relates to a plasma display apparatus for improving image quality by adjusting a rotation speed of a dither mask in relation to an average power level (APL) of input image data.

A plasma display device according to an embodiment of the present invention for achieving the above object is to implement the grayscale of the image using a plasma display panel for displaying an image, a dither mask, the average power of the input image data When the level (Average Power Level: APL) is the first level (APL 1), the dither mask is rotated at the first speed, and the second speed is slower than the first speed when the average power level is higher than the first level. And a driver for rotating the dither mask.

Also, the driver increases the rotation speed of the dither mask when the average power level of the input image data is equal to or less than the threshold level.

In addition, the driver reduces the rotation speed of the dither mask when the average power level of the input image data is equal to or greater than the threshold level.

In addition, a 1st speed is more than 1 time and 10 times or less of a 2nd speed.

Hereinafter, a plasma display device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view for explaining an example of the configuration of a plasma display device according to an embodiment of the present invention.

1, a plasma display apparatus according to an embodiment of the present invention includes a plasma display panel 100 and a driver 110.

The plasma display panel 100 displays an image. In addition, the plasma display panel 100 may include a first electrode and a second electrode parallel to each other, and may also include a third electrode crossing the first electrode and the second electrode.

The driver 110 implements a gray level of an image by using a dither mask, and, when the average power level APL of the input image data is the first level APL 1, the first speed. The dither mask is rotated, and the dither mask is rotated at a second speed slower than the first speed at a second level where the average power level is higher than the first level.

Here, in FIG. 1, only the case in which the driving unit 110 is formed in one board form is illustrated, but in the present invention, the driving unit 110 is divided into a plurality of board forms according to electrodes formed on the plasma display panel 100. It is also possible to lose.

For example, the driver 110 may include a first driver (not shown) for driving the first electrode of the plasma display panel 100, a second driver for driving the second electrode, and a third for driving the third electrode. It can be divided into a driving unit (not shown).

The driving unit 110 of the plasma display device of the present invention will be more clearly described later.

Next, FIG. 2 is a view for explaining an example of a structure of a plasma display panel that may be included in a plasma display device according to an embodiment of the present invention.

Referring to FIG. 2, a plasma display panel that may be included in a plasma display apparatus according to an exemplary embodiment of the present invention has a front substrate 201 in which first electrodes 202 and Y and second electrodes 203 and Z are parallel to each other. ) And the rear substrate 211 on which the third electrodes 213 and X intersecting the first electrodes 202 and Y and the second electrodes 203 and Z are formed.

An electrode such as first electrodes 202 and Y and second electrodes 203 and Z may be formed on the front substrate 201. The first electrodes 202 and Y and the second electrodes 203 and Z may generate a discharge in a discharge space, that is, a discharge cell, and maintain the discharge of the discharge cell.

The dielectric layer covers the first electrode 202 and the second electrode 203 and Z on the front substrate 201 where the first electrode 202 and the second electrode 203 and Z are formed. For example, upper dielectric layer 204 may be formed.

This upper dielectric layer 204 limits the discharge current of the first electrode 202, Y and the second electrode 203, Z and between the first electrode 202, Y and the second electrode 203, Z. Can be insulated.

A protective layer 205 may be formed on the upper dielectric layer 204 to facilitate a discharge condition. The protective layer 205 may be formed through a method of depositing a material such as magnesium oxide (MgO) on the upper dielectric layer 204.

Meanwhile, electrodes, for example, third electrodes 213 and X are formed on the rear substrate 211, and third electrodes 213 and X are formed on the rear substrate 211 on which the third electrodes 213 and X are formed. A dielectric layer, such as lower dielectric layer 215, may be formed to cover the gap.

The lower dielectric layer 215 may insulate the third electrodes 213 and X.

On top of the lower dielectric layer 215, a partition 212, such as a stripe type, a well type, a delta type, a honeycomb type, for partitioning a discharge cell, that is, a discharge cell, is formed. Can be formed. Accordingly, discharge cells such as red (R), green (G), and blue (B) may be formed between the front substrate 201 and the rear substrate 211.

In addition to the red (R), green (G), and blue (B) discharge cells, it is also possible to further form a white (W) or yellow (Yellow: Y) discharge cell.

On the other hand, the pitch of the red (R), green (G) and blue (B) discharge cells in the plasma display panel that can be included in the plasma display device according to an embodiment of the present invention may be substantially the same. The pitches of the red (R), green (G) and blue (B) discharge cells may be varied to match the color temperature in the red (R), green (G) and blue (B) discharge cells.

In this case, the pitch may be different for each of the red (R), green (G), and blue (B) discharge cells, but the pitch of one or more discharge cells among the red (R), green (G), and blue (B) discharge cells. May be different from the pitch of other discharge cells. For example, the pitch of the red (R) discharge cells is the smallest, and the pitch of the green (G) and blue (B) discharge cells may be larger than the pitch of the red (R) discharge cells.

Here, the pitch of the green (G) discharge cells may be substantially the same as or different from the pitch of the blue (B) discharge cells.

In addition, the plasma display panel that may be included in the plasma display apparatus according to an exemplary embodiment of the present invention may have not only the structure of the partition 212 illustrated in FIG. 2 but also the structure of the partition having various shapes. For example, the partition 212 includes a first partition 212b and a second partition 212a, where the height of the first partition 212b and the height of the second partition 212a are different from each other. At least one of the first barrier rib 212b and the second barrier rib 212a, and a channel type barrier rib structure having a channel usable as an exhaust passage, at least one of the first barrier rib 212b and the second barrier rib 212a. Grooved partition wall structure having a groove formed in the groove will be possible.

Here, in the case of the differential partition structure, the height of the first partition 212b of the first partition 212b or the second partition 212a may be lower than the height of the second partition 212a. In addition, in the case of the channel barrier rib structure or the groove barrier rib structure, a channel or a groove may be formed in the first barrier rib 212b.

On the other hand, in the plasma display panel that can be included in the plasma display device according to an embodiment of the present invention, although the red (R), green (G) and blue (B) discharge cells are shown and described as being arranged on the same line, It may be possible to arrange them in other shapes. For example, a delta type arrangement in which red (R), green (G) and blue (B) discharge cells are arranged in a triangular shape may be possible. In addition, the shape of the discharge cell may also be a variety of polygonal shapes, such as pentagonal, hexagonal, as well as rectangular.

In addition, in FIG. 2, only the case where the partition wall 212 is formed on the rear substrate 211 is illustrated, but the partition wall 212 may be formed on at least one of the front substrate 201 and the rear substrate 211.

Here, a predetermined discharge gas may be filled in the discharge cell partitioned by the partition wall 212.

In addition, a phosphor layer 214 that emits visible light for image display may be formed in the discharge cells partitioned by the partition wall 212. For example, red (R), green (G), and blue (B) phosphor layers may be formed.

In addition to the red (R), green (G), and blue (B) phosphors, it is also possible to further form a white (W) and / or yellow (Y) phosphor layer.

In addition, the phosphor layers 214 of the red (R), green (G), and blue (B) discharge cells may have substantially the same thickness or may differ from one or more. For example, if the thickness of the phosphor layer 214 in at least one of the red (R), green (G), and blue (B) discharge cells is different from the other discharge cells, green (G) or blue (B) The thickness of the phosphor layer 214 in the discharge cell may be thicker than the thickness of the phosphor layer 214 in the red (R) discharge cell. Here, the thickness of the phosphor layer 214 in the green (G) discharge cell may be substantially the same as or different from the thickness of the phosphor layer 214 in the blue (B) discharge cell.

In the above description, only one example of the plasma display panel which may be included in the plasma display apparatus according to the exemplary embodiment of the present invention is illustrated and described. However, one embodiment of the present invention is not limited to the plasma display panel having the above-described structure. To reveal. For example, the description hereinabove illustrates only the case where the top dielectric layer at number 204 and the bottom dielectric layer at number 215 are each one layer, but one or more of these top dielectric layers and bottom dielectric layers are a plurality of layers. It can also be layered.

In addition, a black layer (not shown) may be further formed on the partition 212 to prevent reflection of the external light due to the partition 212.

In addition, a black layer (not shown) may be further formed at a specific position on the front substrate 201 corresponding to the partition 212.

In addition, the width or thickness of the third electrode 213 formed on the rear substrate 211 may be substantially constant, but the width or thickness inside the discharge cell may be different from the width or thickness outside the discharge cell. will be. For example, the width or thickness inside the discharge cell may be wider or thicker than that outside the discharge cell.

Next, FIG. 3 is a diagram for explaining an example in the case where at least one of the first electrode or the second electrode is a plurality of layers.

Referring to FIG. 3, at least one of the first electrode 202 or the second electrode 203 may be formed of a plurality of layers, for example, two layers.

For example, in consideration of light transmittance and electrical conductivity, at least one of the first electrode 202 or the second electrode 203 is made of silver (silver) to emit light generated in the discharge cell to the outside and to secure driving efficiency. Bus electrodes 202b and 203b including a substantially opaque material such as Ag) and transparent electrodes 202a and 203a including a transparent material such as transparent indium tin oxide (ITO). .

As such, when the first electrode 202 and the second electrode 203 include the transparent electrodes 202a and 203a, visible light generated in the discharge cell can be effectively emitted when emitted to the outside of the plasma display panel. .

In addition, when the first electrode 202 and the second electrode 203 include the bus electrodes 202b and 203b, the first electrode 202 and the second electrode 203 include only the transparent electrodes 202a and 203a. In this case, the driving efficiency can be reduced because the electrical conductivity of the transparent electrodes 202a and 203a is relatively low, and it is possible to compensate for the low electrical conductivity of the transparent electrodes 202a and 203a which can cause such a reduction in the driving efficiency. Can be.

As described above, in the case where the first electrode 202 and the second electrode 203 include the bus electrodes 202b and 203b, the transparent electrodes 202a and 203b may be used to prevent reflection of external light by the bus electrodes 202b and 203b. Black layers 320 and 321 may be further provided between the 203a and the bus electrodes 202b and 203b.

Next, FIG. 4 is a figure for explaining an example in the case where at least one of a 1st electrode or a 2nd electrode is a single layer.

Referring to FIG. 4, the first electrodes 202 and Y and the second electrodes 203 and Z are one layer. For example, the first electrodes 202 and Y and the second electrodes 203 and Z may be electrodes (ITO-Less) in which the transparent electrode of numeral 202a or 203a is omitted in FIG. 3.

At least one of the first electrode 202 and Y or the second electrode 203 and Z may include a substantially opaque electrically conductive metal material. For example, it may include a material having excellent electrical conductivity such as silver (Ag), copper (Cu), aluminum (Al), and the like, and a material having a lower cost than a transparent material such as indium tin oxide (ITO). .

In addition, at least one of the first electrode 202 and the second electrode 203 and Z may be darker in color than the upper dielectric layer of FIG. 2.

As such, when at least one of the first electrode 202 and the second electrode 203 and Z is a single layer, the manufacturing process is simpler than in the case of FIG. 3. For example, in the case of FIG. 3, the bus electrodes 202b and 203b are formed after the transparent electrodes 202a and 203a are formed in the process of forming the first electrodes 202 and Y and the second electrodes 203 and Z. 4 again, the first electrode 202 and Y and the second electrode 203 and Z can be formed in one process because the single layer structure of FIG.

In addition, as shown in FIG. 4, when the first electrodes 202 and Y and the second electrodes 203 and Z are formed in a single layer, the manufacturing process is simplified and relatively expensive indium-tin-oxide (ITO) or the like. Since it is not necessary to use a transparent material of the manufacturing cost can be reduced.

Meanwhile, discoloration of the front substrate 201 is prevented between the first electrodes 202 and Y and the second electrodes 203 and Z and the front substrate 201, and the first electrode 202 or Y or the second electrode ( Black layers 400a and 400b having a darker color than at least one of 203 and Z) may be further provided. That is, when the front substrate 201 and the first electrode 202, Y or the second electrode 203, Z are in direct contact, the first electrode 202, Y or the second electrode 203, Z is directly in contact with each other. Migration phenomenon may occur in which a predetermined area of the front substrate 201 that is in contact with the yellow color is changed. The black layers 400a and 400b may prevent the migration of the front substrate 201 by preventing the migration phenomenon. It can be.

The black layers 400a and 400b may include a black material having a substantially dark color, for example, ruthenium (Ru).

As such, when the black layers 400a and 400b are provided between the front substrate 201 and the first electrodes 202 and Y and the second electrodes 203 and Z, the first electrodes 202 and Y may be provided. Even if the second electrodes 203 and Z are made of a material having high reflectance, generation of reflected light can be prevented.

As such, the structure of the plasma display panel which may be included in the plasma display apparatus according to the exemplary embodiment may be variously changed.

Next, FIG. 5 is a diagram for describing an image frame for implementing grayscale of an image in a plasma display device according to an embodiment of the present invention.

Referring to FIG. 5, an image frame for implementing gray levels of an image in a plasma display device according to an embodiment of the present invention may be divided into a plurality of subfields having different emission counts.

Although not shown, one or more subfields among the plurality of subfields may be grayed out according to a reset period for initializing discharge cells, an address period for selecting discharge cells to be discharged, and the number of discharges. It can be divided into the sustain period to implement.

For example, when an image is to be displayed with 256 gray scales, for example, one image frame is divided into eight subfields SF1 to SF8 as shown in FIG. 5, and each of the eight subfields SF1 to SF8, respectively. Can be subdivided into a reset period, an address period and a sustain period.

The gray scale weight of the corresponding subfield may be set by adjusting the number of the sustain signals supplied in the sustain period. That is, a predetermined gray scale weight can be given to each subfield using the sustain period. For example, the gray scale weight of each subfield is 2 ⁿ by setting the gray scale weight of the first subfield to 2 ⁰ and the gray scale weight of the second subfield to 2 ¹ (where n = 0, 1). , 2, 3, 4, 5, 6, and 7) to increase the gray scale weight of each subfield. As described above, the number of sustain signals supplied in the sustain period of each subfield is adjusted according to the gray scale weight in each subfield, thereby implementing gray levels of various images.

A plasma display panel according to an embodiment of the present invention uses a plurality of image frames to implement an image, for example, to display an image of 1 second. For example, 60 image frames are used to display one second of images. In this case, the length T of one image frame may be at most 1/60 second, that is, 16.67 ms.

In FIG. 5, only one image frame is composed of eight subfields. However, the number of subfields constituting one image frame may be variously changed. For example, one video frame may be configured with 12 subfields from the first subfield to the twelfth subfield, or one video frame may be configured with 10 subfields.

In addition, in FIG. 5, subfields are arranged in increasing order of gray scale weight in one image frame. Alternatively, subfields may be arranged in order of decreasing gray scale weight in one image frame. Alternatively, subfields may be arranged regardless of the gray scale weight.

6 is a view for explaining an example of the operation of the plasma display device according to an embodiment of the present invention.

Referring to FIG. 6, an example of the operation of the plasma display apparatus in any one of the plurality of subfields included in the image frame as shown in FIG. 5 is shown. It will be appreciated that the driving signals to be described below are supplied by the driving unit 110 of FIG. 1.

First, the first ramp-down signal may be supplied to the first electrode Y in the pre-reset period before the reset period.

In addition, while the first falling ramp signal is supplied to the first electrode Y, a pre-sustain signal in a polarity opposite to the first falling ramp signal may be supplied to the second electrode Z.

Here, the first falling ramp signal supplied to the first electrode Y may gradually fall to the first voltage V1.

In addition, the pre-sustain signal can keep the pre-sustain voltage Vpz substantially constant. Here, the pre-sustain voltage Vpz may be a voltage of the sustain signal SUS supplied in a subsequent sustain period, that is, a voltage approximately equal to the sustain voltage Vs.

As such, when the first falling ramp signal is supplied to the first electrode Y and the presuspension signal is supplied to the second electrode Z in the pre-reset period, a wall of a predetermined polarity is formed on the first electrode Y. Wall charges are accumulated, and wall charges of opposite polarity to the first electrode Y are accumulated on the second electrode Z. For example, positive wall charges may be accumulated on the first electrode Y, and negative wall charges may be accumulated on the second electrode Z.

This makes it possible to generate a set-up discharge of sufficient intensity in the subsequent reset period, which in turn makes it possible to perform the initialization sufficiently stably.

In addition, even when the voltage of the rising ramp signal Ramp-Up supplied to the first electrode Y becomes smaller in the reset period, it is possible to generate the setup discharge of sufficient intensity.

From the viewpoint of securing the driving time, a pre-reset period is included before the reset period in the subfields arranged first in time among the subfields of the image frame, or before the reset period in two or three subfields of the subfields of the image frame. It is also possible to include a pre-reset period.

Alternatively, this pre-reset period may be omitted in all subfields.

After the pre-reset period, in a set-up period of a reset period for initialization, a ramp-up signal in a direction opposite to that of the first falling ramp signal may be supplied to the first electrode Y.

Here, the rising ramp signal may be a first rising ramp signal gradually increasing with the first slope from the second voltage V2 to the third voltage V3 and a second voltage from the third voltage V3 to the fourth voltage V4. It may include a second rising ramp signal rising to the slope.

In this setup period, a weak dark discharge, that is, setup discharge, occurs in the discharge cell by the rising ramp signal. By this setup discharge, some wall charges can be accumulated in the discharge cells.

Here, the second slope of the second rising ramp signal may be gentler than the first slope. As such, when the second slope is made gentler than the first slope, the voltage is increased relatively quickly until the setup discharge occurs, and the voltage is increased relatively slowly while the setup discharge occurs. The amount of light generated by the setup discharge can be reduced.

Accordingly, the contrast characteristic can be improved.

In a set-down period after the set-up period, a second ramp-down signal in a direction opposite to that of the ramp ramp signal may be supplied to the first electrode Y after the ramp ramp signal.

Here, the second falling ramp signal may gradually fall from the fifth voltage V5 to the sixth voltage V6.

As a result, weak erase discharge, that is, set-down discharge, occurs in the discharge cell. By this set-down discharge, wall charges such that address discharge can be stably generated in the discharge cells remain uniformly.

Next, FIGS. 7A to 7B are diagrams for describing another form of the rising ramp signal or the second falling ramp signal.

First, referring to FIG. 7A, the rising ramp signal gradually increases from the third voltage V3 to the fourth voltage V4 after rapidly rising from the second voltage V2 to the third voltage V3.

As such, the rising ramp signal may rise gradually with different inclinations over two stages, as shown in FIG. 6, and in various forms, such as gradually rising in one stage as shown here in FIG. 7A. It is possible to change.

Next, referring to FIG. 7B, the second falling ramp signal has a form in which the voltage gradually decreases from the eighth voltage V8. Here, the eighth voltage V8 may be substantially the same as or different from the third voltage V3.

As described above, the second falling ramp signal may be changed in various forms, such as a different point in time at which the voltage falls.

Meanwhile, in the address period after the reset period, a scan bias signal that substantially maintains the lowest voltage of the second falling ramp signal, that is, a voltage higher than the sixth voltage V6 may be supplied to the first electrode Y.

In addition, the scan signal Scan, which decreases from the scan bias signal by the scan voltage qVy, may be supplied to the first electrodes Y1 to Yn.

For example, the first scan signal Scan 1 is supplied to the first first electrode Y1 of the plurality of first electrodes Y, and then the second scan signal (2) is applied to the second first electrode Y2. Scan 2) is supplied, and the n-th scan signal Scan n is supplied to the n-th first electrode Yn.

On the other hand, the width of the scan signal in units of subfields may vary. That is, the width of the scan signal Scan in at least one subfield may be different from the width of the scan signal Scan in other subfields. For example, the width of the scan signal Scan in the subfield located later in time may be smaller than the width of the scan signal Scan in the subfield located earlier. In addition, the scan signal scan width decreases according to the arrangement order of the subfields gradually, such as 2.6 ms (microseconds), 2.3 ms (microseconds), 2.1 ms (microseconds), 1.9 ms (microseconds), and the like. Or 2.6 ㎲ (microseconds), 2.3 ㎲ (microseconds), 2.3 ㎲ (microseconds), 2.1 ㎲ (microseconds) ... 1.9 ㎲ (microseconds), 1.9 ㎲ (microseconds) It could be done.

As such, when the scan signal Scan is supplied to the first electrode Y, a data signal rising by the magnitude of the data voltage VVd may be supplied to the third electrode X to correspond to the scan signal. .

As the scan signal Scan and the data signal Data are supplied, the voltage difference between the voltage of the scan signal and the data voltage Vd of the data signal and the wall voltage generated by the wall charges generated in the reset period are In addition, address discharge may occur in a discharge cell to which the voltage Vd of the data signal is supplied.

Here, a sustain bias signal may be supplied to the second electrode Z to prevent address discharge from becoming unstable due to interference of the second electrode Z in the address period.

Here, the sustain bias signal may maintain a substantially constant sustain bias voltage Vz smaller than the voltage of the sustain signal supplied in the sustain period and greater than the voltage of the ground level GND.

Thereafter, in the sustain period for displaying an image, the sustain signal SUS may be supplied to at least one of the first electrode Y and the second electrode Z. FIG. For example, the sustain signal SUS may be alternately supplied to the first electrode Y and the second electrode Z. FIG.

When the sustain signal SUS is supplied, the discharge cell selected by the address discharge is added with the wall voltage in the discharge cell and the sustain voltage Vs of the sustain signal SUS, and the first electrode when the sustain signal SUS is supplied. A sustain discharge, that is, a display discharge, may be generated between (Y) and the second electrode Z.

Next, FIG. 8 is a diagram for explaining an average power level.

Referring to FIG. 8, an average power level (APL) is a method of adjusting the number of sustain signals in relation to the size of a portion where an image is displayed on a plasma display panel. That is, the average power level is determined according to the number of discharge cells that are turned on among the discharge cells of the plasma display panel.

Preferably, as the value of the average power level APL increases, the number of sustain signals per unit gray scale decreases, and as the value of the average power level APL decreases, the number of sustain signals per unit gray scale increases.

For example, when an image is displayed on a portion of a relatively small area on the screen of the plasma display panel 600 as shown in (a), that is, a discharge cell that is turned on among discharge cells formed in the plasma display panel 600. When the number of cells is relatively small (in this case, the APL level is relatively low), since the number of discharge cells contributing to the image display is relatively small, the sustain per unit gradation supplied to each discharge cell contributing to the image display is relatively small. Make the number of signals relatively large. Accordingly, the overall brightness of the image can be increased.

On the contrary, when an image is displayed on a portion of a relatively large area on the screen of the plasma display panel 600 as shown in (b), that is, the number of discharge cells turned on among the discharge cells formed in the plasma display panel 600 is relatively high. In many cases (in this case, the APL level is relatively high), since the number of discharge cells contributing to the image display is relatively large, the number of sustain signals per unit gradation supplied to each discharge cell contributing to the image display is determined. Relatively few. Accordingly, a sudden increase in the total power consumption of the plasma display panel 600 is prevented.

As an example, when the average power level is a level, in this case, the number of sustain signals per unit gradation is N.

In addition, when the average power level is a b level higher than the above-described a level, the number of sustain signals per unit gray level may be M less than N described above.

Next, FIG. 9 is a diagram for explaining an example of the configuration of a driver for halftone correction.

Referring to FIG. 9, the driver may include an inverse gamma corrector 900, a halftone corrector 910, and a subfield mapping unit 920.

The inverse gamma correction unit 900 may reverse gamma correct the input image data.

The halftone corrector 910 may correct half-tones of the input image data using a dither mask.

The subfield mapping unit 920 may subfield map the input image data. Accordingly, subfield mapping data is output. The subfield mapping data may be supplied to the third electrode as the data signal described above with reference to FIG. 6.

Next, FIG. 10 is a figure for explaining an example of the halftone correction method using a dither mask.

Referring to FIG. 10, an example of a method of halftone correction of image data using a 2 × 2 dither mask is illustrated.

Assume that gray scale 1 is implemented when one discharge cell is turned on. Here, a dither mask may be used to implement a few gray scales, for example, 0.25 gray scales smaller than gray scale 1.

For example, to realize a gradation of 0.25, the discharge cell of the number 1000b of the four discharge cells 1000a, 1000b, 1000c, and 1000d in the 2 × 2 dither mask is turned on, as shown in (a), and the remaining discharge cells are turned on. Off.

Then, only one of the four discharge cells 1000a, 1000b, 1000c, and 1000d is on and the other three discharge cells are off, but visually, the four discharge cells 1000a, 1000b, 1000c and 1000d) appear to implement a gradation of 0.25 as shown in (b).

In this way, decimal gradations can be implemented using integer gradations. Accordingly, the image quality of the image can be improved. This image processing method is an example of a halftone correction method.

In addition, the dither mask may be rotated to further improve image quality. This is as follows.

Next, FIG. 11 is a diagram for explaining the rotation of the dither mask.

Referring to FIG. 11, the discharge cell of the number 1000a of the four discharge cells 1000a, 1000b, 1000c, and 1000d in the 2 × 2 dither mask is turned on and the remaining discharge cells are turned off as shown in (a). . Here, in FIG. 11, the discharge cells to be turned on are relatively dark.

Thereafter, as shown in (b), the discharge cells of the number 1000b of the four discharge cells 1000a, 1000b, 1000c, and 1000d are turned on and the remaining discharge cells are turned off. In the case of (b), the case of (a) is rotated 90 degrees clockwise.

In this way, the case of (b) can be rotated clockwise 90 ° again as shown in (c), and the case of (c) can be rotated 90 degrees clockwise again as shown in (d). .

As described above, when halftone correction is performed while the dither mask is rotated, it is possible to suppress occurrence of dithering noise phenomenon in which a dither mask of a specific pattern is displayed on the screen.

In addition, the rotation speed of the dither mask may be adjusted in relation to the average power level to further improve the image quality of the image. This is as follows.

12 is a view for explaining an example of a method of adjusting the rotational speed of the dither mask in relation to the average power level.

Referring to FIG. 12, when the average power level APL of the input image data is the first level APL 1, the dither mask is rotated at a first speed.

For example, in the first frame, the discharge cells of a of the four discharge cells a, b, c, and d in the 2x2 dither mask are turned on and the remaining discharge cells are turned off. In FIG. 12, the discharge cells that are turned on are relatively dark.

Next, in the second frame, the discharge cells of b of the four discharge cells a, b, c, and d are turned on and the remaining discharge cells are turned off. That is, halftone correction is performed while rotating the dither mask by 90 ° clockwise.

In this manner, halftone correction is performed while rotating the dither mask by 90 ° for each frame.

On the other hand, when the average power level of the input image data is a second level higher than the first level APL1, the dither mask is rotated at a second speed slower than the first speed.

For example, in the first frame and the second frame, one of the four discharge cells a, b, c, and d in the 2 × 2 dither mask is turned on and the remaining discharge cells are turned off. Let's do it.

Next, in the third and fourth frames, the discharge cells of b of the four discharge cells a, b, c, and d are turned on and the remaining discharge cells are turned off.

As described above, when the average power level is a relatively high second level, halftone correction may be performed while rotating the dither mask by 90 ° clockwise every two frames.

As described above, the reason for setting is as follows.

When the average power level is a relatively low first level, the number of discharge cells that are turned on among the total discharge cells is relatively small. Accordingly, even when the dither mask is rotated at a relatively high speed, the number of conversions of the entire image data is relatively small. In addition, if the dither mask is rotated at a high speed, the image quality of the image may be further improved due to the reduction of the dither noise.

On the other hand, when the average power level is a relatively high second level, the number of discharge cells that are turned on among the total discharge cells is relatively large. Accordingly, when the dither mask is rotated at a relatively high speed, the number of conversions of the entire image data may increase rapidly. As a result, the generation of the displacement current may increase rapidly, which may cause electrical damage to the switching elements of the driving unit.

Therefore, when the average power level is relatively low, the rotation speed of the dither mask is relatively high. On the other hand, when the average power level is relatively high, the rotation speed of the dither mask is relatively slow.

In addition, the first speed when the average power level is the first level and the second speed when the average power level is the second level to further improve the image quality of the image and more effectively prevent electrical damage to the driver. It can be set more than 1 time and less than 10 times.

Next, FIGS. 13A to 13B are views for explaining another example of a method of adjusting the rotation speed of the dither mask in relation to the average power level.

First, referring to FIG. 13A, when the average power level of the input image data is less than or equal to the threshold level, the rotation speed of the dither mask may be increased.

For example, assuming that the threshold level is a P1 level, when the average power level of the input image data is larger than the threshold level P1, the rotation speed of the dither mask is maintained at S1. On the other hand, when the average power level of the input image data is below the threshold level P1, the rotation speed of the dither mask may be set to S2 which is faster than S1.

Next, referring to FIG. 13B, when the average power level of the input image data is greater than or equal to the threshold level, the rotation speed of the dither mask may be decreased.

For example, assuming that the threshold level is the P2 level, when the average power level of the input image data is smaller than the threshold level P2, the rotation speed of the dither mask is maintained at S3. On the other hand, when the average power level of the input image data is equal to or higher than the threshold level P2, the rotation speed of the dither mask may be set to S4 which is slower than S3.

Next, FIG. 14 is a view for explaining another example of a method of adjusting the rotation speed of the dither mask in relation to the average power level.

Referring to FIG. 14, when the average power level of the input image data is included in a relatively low region, the rotation speed of the dither mask may be set to 1 ns. That is, the dither mask may be rotated at a predetermined angle every 1 ns.

In addition, when the average power level is included in the b region higher than the a region, the dither mask is rotated at a predetermined angle every 2 ns. When the average power level is included in the c region higher than the b region, the dither mask is rotated at a predetermined angle every 3 ns. If the average power level is included in the d region higher than the c region, the dither mask may be rotated at a predetermined angle every 4 ns.

As described above, the rotation speed of the dither mask may be adjusted in various ways.

As such, the technical configuration of the present invention described above can be understood by those skilled in the art that the present invention can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. For example, although only the case where 2x2 dither mask is used was demonstrated above, it is also possible to use a 3x3 dither mask, a 4x4 dither mask, a 4x3 dither mask, and an 8x8 dither mask.

Therefore, the exemplary embodiments described above are to be understood as illustrative and not restrictive in all respects, and the scope of the present invention is indicated by the appended claims rather than the foregoing detailed description, and the meaning and scope of the claims are as follows. And all changes or modifications derived from the equivalent concept should be interpreted as being included in the scope of the present invention.

As described in detail above, the plasma display apparatus according to the exemplary embodiment of the present invention has an effect of improving image quality and preventing electrical damage to the driving unit by adjusting the rotation speed of the dither mask in relation to the average power level. .

Claims (4)

A plasma display panel for displaying an image, The dither mask is implemented using a dither mask, and when the average power level (APL) of the input image data is the first level APL1, the dither mask is operated at a first speed. And rotate the dither mask at a second speed slower than the first speed when the average power level is higher than the first level. Plasma display device comprising a. The method of claim 1, The driving unit And a rotation speed of the dither mask is increased when the average power level of the input image data is equal to or less than a threshold level. The method of claim 1, The driving unit And a rotation speed of the dither mask when the average power level of the input image data is greater than or equal to a threshold level. The method of claim 1, And the first speed is greater than one time and less than ten times the second speed.

Images