KR20080014351A - Plasma display apparatus - Google Patents

Abstract

A plasma display device is provided to decrease a false contour noise by dispersing a grayness weighting of a specific sub-field into adjacent sub-fields. A plasma display device includes a PDP(Plasma Display Panel)(100) and a driving unit(110) which represents a grayness of an image using plural image frames containing plural sub-fields. The image frame includes first to third image frames. A sum of grayness weights of on-sub-fields of a first image frame is a first grayness. A sum of grayness weights of on-sub-fields of a second image frame is a second grayness greater than the first grayness. A sum of grayness weights of on-sub-fields of a third image frame is a third grayness greater than the second grayness. A first number of sub-fields are allocated from a first sub-field to the last on-sub-field within the first image frame. A second number of sub-fields are allocated from a first sub-field to the last on-sub-field within the second image frame. A third number of sub-fields are allocated from a first sub-field to the last on-sub-field within the third image frame. The third number is greater than the second number greater than the first number.

Description

Plasma Display Apparatus {Plasma Display Apparatus}

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

2A to 2B are views for explaining an example of a plasma display panel that can be included in a plasma display device according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating an image frame for implementing grayscale of an image in a plasma display device according to an embodiment of the present invention. FIG.

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

5A to 5B are diagrams for explaining another form of the rising ramp signal or the second falling ramp signal.

Fig. 6 is a diagram for explaining another type of the sustain signal.

7 is a diagram for explaining generation of noise such as pseudo contour noise.

8A to 8B are diagrams for explaining a first embodiment of a method for reducing noise such as pseudo contour noise.

9 is a diagram for explaining a second embodiment of a method for reducing noise such as pseudo contour noise.

10A to 10B are diagrams for explaining a third embodiment of a method for reducing noise such as pseudo contour noise.

11A to 11B are views for explaining a fourth embodiment of a method for reducing noise such as pseudo contour noise.

<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 includes a plasma display panel having electrodes formed thereon, and a driving unit supplying predetermined 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.

Meanwhile, in the conventional plasma display apparatus, when an image is implemented on a screen, noise such as contour noise occurs, and thus the image quality of the implemented image is deteriorated.

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a plasma display apparatus in which noise generation such as pseudo contour noise is reduced by adjusting gray scale weights of at least one subfield of an image frame.

According to an embodiment of the present invention, a plasma display apparatus includes a plasma display panel for implementing an image using plasma discharge, and a plurality of image frames including a plurality of subfields. And a driver configured to implement gradation of an image, wherein the plurality of image frames include a first image frame, a second image frame, and a third image frame, wherein the gradation weights of the on subfields of the first image frame The sum is the first gradation, the sum of the gradation weights of the on subfields of the second image frame is the second gradation greater than the first gradation, and the sum of the gradation weights of the on subfields of the third image frame is greater than the second gradation Subfills from the first subfield disposed in time in the first grayscale to the last subfield arranged in time in the third grayscale; The number of times is the first number, and the number of subfields from the first subfield disposed in time of the second image frame to the last subfield disposed in time in the on-subfield is a second number greater than the first number. For example, the number of subfields from the first subfield disposed in time of the third image frame to the last subfield disposed in time in the on subfield may be less than the second number and more than the first number.

Further, the on subfield is preferably a subfield in which the data signal is supplied to the third electrode in the address period.

In addition, the first image frame, the second image frame, and the third image frame are preferably continuous in time.

In addition, the gray scale weight of the subfield disposed last in time among the on subfields of the second image frame is preferably smaller than the gray scale weight of the subfield disposed last in time among the on subfields of the third image frame.

In addition, the gray scale weights and the second gray scale weights of the subfields disposed closest to the last one among the subfields among the subfields disposed between the last subfield disposed in time and the first placed subfield in time and the second The sum of the gray scale weights of the subfields disposed last in time among the on subfields of the image frame may be substantially the same as the gray scale weights of the subfields disposed most recently in time among the on subfields of the third image frame.

In addition, the gray scale weights of the subfield disposed last in the subfield disposed between the subfield disposed first in time of the second image frame and the subfield disposed last in time among the on subfields and the nearest subfield in time, It is preferable that the gray scale weights of the subfields disposed last in time among the on subfields of the second image frame are substantially the same.

In addition, it is preferable to determine the number of sustain signals supplied to at least one of the first electrode and the second electrode in the sustain period of the gray scale weight.

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 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 driver 110 implements a gray level of an image implemented on the plasma display panel 100 using a plurality of image frames including a plurality of subfields.

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, when the first electrode and the second electrode parallel to each other and the third electrode crossing the first electrode and the second electrode are formed in the plasma display panel 100 included in the plasma display device of the present invention, The driver 110 is divided into a first driver (not shown) for driving the first electrode, a second driver (not shown) for driving the second electrode, and a third driver (not shown) for driving the third electrode. It can be lost.

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

Here, the plasma display panel 100 displays an image using plasma discharge. An example of such a plasma display panel 100 will be described in detail with reference to FIGS. 2A to 2B.

2A to 2B are views for explaining an example of a plasma display panel that may be included in a plasma display device according to an embodiment of the present invention.

First, referring to FIG. 2A, the plasma display panel includes a front substrate 201 in which first electrodes 202 and Y and second electrodes 203 and Z are parallel to each other, the first electrodes 202 and Y, and The rear substrate 211 on which the third electrodes 213 and X intersecting the second electrodes 203 and Z are formed may be bonded to each other.

Here, the electrodes formed on the front substrate 201, preferably the first electrodes 202 and Y and the second electrodes 203 and Z, generate a discharge in a discharge space, that is, a discharge cell, and discharge the same. The discharge of the cell can be maintained.

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. Preferably, the upper dielectric layer 204 can 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 is formed on the top surface of the upper dielectric layer 204 to facilitate discharge conditions. 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.

On the other hand, the electrode, preferably the third electrode (213, X) is formed on the back substrate 211, the third electrode 213, is formed on the upper side of the back substrate 211, the third electrode (213, X) is formed A dielectric layer, preferably lower dielectric layer 215 may be formed to cover X).

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 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 different 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 included in the plasma display apparatus according to the exemplary embodiment of the present invention may have not only the structure of the partition wall 212 illustrated in FIG. 2A but also the structure of the partition wall 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, it is preferable that the height of the first partition 212b of the first partition 212b or the second partition 212a is lower than the height of the second partition 212a. In addition, in the case of the channel type barrier rib structure or the groove type barrier rib structure, it is preferable that the channel is formed in the first barrier rib 212b or the groove is formed.

On the other hand, in the plasma display panel 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, they may be arranged in different shapes. It will be possible. 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.

Here, it is preferable that a predetermined discharge gas is filled in the discharge cells partitioned by the partition walls 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.

Meanwhile, in the above description of FIG. 2A, only the case where the first electrode 202 and the second electrode 203 are formed of one layer each is illustrated and described. However, the first electrode 202 or the second electrode is different from the above description. It is also possible that one or more of 203 consists of a plurality of layers. This will be described with reference to FIG. 2B.

Referring to FIG. 2B, the first electrode 202 and the second electrode 203 may be formed of a plurality of layers, for example, two layers.

In particular, in consideration of light transmittance and electrical conductivity, the first electrode 202 and the second electrode 203 are substantially made of silver (Ag) in order to emit light generated in the discharge cell to the outside and to secure driving efficiency. It is preferable to include bus electrodes 202b and 203b including an opaque material and transparent electrodes 202a and 203a including a transparent material such as transparent indium tin oxide (ITO).

As such, the reason for the first electrode 202 and the second electrode 203 to include the transparent electrodes 202a and 203a is that the visible light generated in the discharge cell is effectively emitted when emitted to the outside of the plasma display panel. To make it possible.

In addition, the reason why the first electrode 202 and the second electrode 203 include the bus electrodes 202b and 203b is that the first electrode 202 and the second electrode 203 are the transparent electrodes 202a and 203a. ), The driving efficiency can be reduced because the electrical conductivity of the transparent electrodes 202a and 203a is relatively low, so that the low electrical conductivity of the transparent electrodes 202a and 203a can cause such a reduction in the driving efficiency. To compensate.

As described above, when the first electrode 202 and the second electrode 203 include the bus electrodes 202b and 203b, the transparent electrodes 202a, It is preferable that a black layer (220, 221) is further provided between the 203a and the bus electrodes 202b and 203b.

Meanwhile, the transparent electrodes 202a and 203a may be omitted in the same structure as in FIG. 2B. For example, the first electrode 202 and the second electrode 203 may be formed of only the bus electrodes 202b and 203b without the transparent electrodes 202a and 203a in FIG. 2B. That is, the first electrode 202 and the second electrode 203 are ITO-Less electrodes made of one layer of the bus electrodes 202b and 203b.

In the meantime, only one example of the plasma display panel included in the plasma display apparatus according to the exemplary embodiment of the present invention is illustrated and described, and the present invention is not limited to the plasma display panel having the above-described structure. 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.

As such, the structure of the plasma display panel according to the present invention may be variously changed.

Next, FIG. 3 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.

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

First, referring to FIG. 3, an image frame for implementing gray levels of an image in a plasma display device according to an embodiment of the present invention is divided into a plurality of subfields having different emission counts.

Although not illustrated, one or more subfields among the plurality of subfields may be grayed out according to a reset period for initializing all 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 (Sustain Period) that implements.

For example, in case of displaying an image with 256 gray levels, one frame is divided into eight subfields SF1 to SF8 as shown in FIG. 3, and each of the eight subfields SF1 to SF8, respectively. Is divided 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.

The plasma display apparatus according to an exemplary embodiment 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 an image of 1 second. In this case, the length T of one frame may be 1/60 second, that is, 16.67 ms.

In FIG. 3, only one image frame is composed of eight subfields. However, the number of subfields forming 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. 3, subfields are arranged in the order of increasing magnitude 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.

Next, referring to FIG. 4, an example of an operation of a plasma display apparatus according to an exemplary embodiment of the present invention in any one of a plurality of subfields included in an image frame as shown in FIG. 3 is shown.

First, the first ramp-down signal may be supplied to the first electrode Y by the driver 110 of FIG. 1 in the pre-reset period before the reset period. It will be appreciated that the various signals to be described later are supplied to the first electrode, the second electrode, or the third electrode by the driver 110 of FIG. 1.

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, it is preferable that the first falling ramp signal supplied to the first electrode Y gradually descends to the tenth voltage V10.

In addition, it is preferable that the pre-sustain signal maintain the pre-sustain voltage Vpz substantially constant. Here, it is preferable that the pre-sustain voltage Vpz is approximately the same voltage as the voltage of the sustain signal SUS supplied in the subsequent sustain period, that is, 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 are accumulated on the first electrode Y, and negative wall charges are 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 include a first rising ramp signal gradually increasing with a first slope from the twentieth voltage V20 to the thirtieth voltage V30 and the second rising ramp signal from the thirtieth voltage V30 to the forty-th voltage V40. 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. This setup discharge causes a certain amount of wall charges to accumulate in the discharge cell.

Here, it is preferable that the second slope of the second rising ramp signal is 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, it is preferable that the second falling ramp signal gradually decreases from the twentieth voltage V20 to the fifty voltage V50.

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.

5A to 5B are diagrams for describing another form of the rising ramp signal or the second falling ramp signal.

First, referring to FIG. 5A, the rising ramp signal gradually increases from the thirtieth voltage V30 to the forty-th voltage V40 after rapidly rising to the thirtieth voltage V30.

As such, the rising ramp signal may rise gradually with different inclinations over two stages, as shown in FIG. 4, and in various forms, such as gradually rising in one stage as shown here in FIG. 5A. It is possible to change.

Next, referring to FIG. 5B, the second falling ramp signal has a form in which the voltage gradually decreases from the thirtieth voltage V30.

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 a voltage higher than the 50 th voltage V50 of the second falling ramp signal may be supplied to the first electrode Y. FIG.

In addition, the scan signal Scan, which decreases from the scan bias signal by the scan voltage ΔVy, may be supplied to all of 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 ΔVd of the data voltage 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 due to the wall charges generated in the reset period. In addition, address discharge is generated in the discharge cells to which the voltage Vd of the data signal is supplied.

Here, it is preferable that the sustain bias signal is supplied to the second electrode Z in order to prevent the address discharge from becoming unstable due to the interference of the second electrode Z in the address period.

Here, it is preferable that the sustain bias signal maintain a substantially constant sustain bias voltage Vz smaller than the voltage of the sustain signal supplied in the sustain period and larger than the voltage of the ground level GND.

Thereafter, the sustain signal SUS may be alternately supplied to the first electrode Y and / or the second electrode Z in the sustain period for displaying an image. The sustain signal SUS preferably has a magnitude of a voltage of ΔVs.

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

6 is a diagram for explaining another type of the sustain signal.

Referring to FIG. 6, a positive sustain signal and a negative sustain signal are alternately supplied to one of the first electrodes Y and the second electrode Z, for example, the first electrode. do.

As described above, it is preferable that the bias signal is supplied to the other electrode, for example, the second electrode Z, while the positive sustain signal and the negative sustain signal are supplied to any one electrode.

Here, the bias signal preferably maintains the voltage at the ground level GND substantially constant.

As shown in FIG. 6, when the sustain signal is supplied only to one of the first electrode Y and the second electrode Z, one of the first electrode Y and the second electrode Z may be used. Only one driving board in which circuits for supplying a sustain signal is arranged is required.

As a result, the overall size of the driving unit can be reduced, thereby reducing the manufacturing cost.

On the other hand, in the plasma display device according to an embodiment of the present invention, the gray scale weight of at least one subfield of the plurality of subfields of the image frame is adjusted to reduce the generation of noise such as contour noise. This is as follows.

7 is a diagram for explaining generation of noise such as pseudo contour noise.

As shown in FIG. 7, it is assumed that one image frame includes a total of eight subfields, that is, the first subfield SF1 through the eighth subfield SF8.

In addition, it is assumed that the gray scale weight of each subfield is determined to be 2 ⁿ (n = 0, 1, 2, 3, 4, 5, 6, 7) according to the arrangement order of the subfields. For example, the gray scale weight of the first subfield is 2 ⁰ , that is, 1, and the gray scale weight of the fifth subfield is 2 ⁴ , that is, 16.

Here, as shown in (a), when the gray value of the image frame is 15, the first, second, third, and fourth subfields may be set as on subfields. In other words, when the data signal is supplied to the third electrode of the plasma display panel in the address period of the first, second, third, and fourth subfields, the sum of the gray scale weights of the on subfields of the image frame may be set to 15. will be.

Here, the on subfield is a subfield to which a data signal is supplied to the third electrode in the address period.

Next, when the gray value of the video frame is 16 as shown in (b), the fifth subfield may be set to an on subfield, and when the gray value of the video frame is 17 as in (c), the first subfield may be set as shown in (c). The field and the fifth subfield may be set to the on subfield, and when the gray value of the image frame is 18 as shown in (d), the second subfield and the fifth subfield may be set to the on subfield. .

Here, let's compare (a) and (b).

(a) and (b) are gray level values, i.e., the sum of the gray scale weights of the on subfield is 15 and 16, and there is a first difference, but in the case of (a), the discharge is uniformly distributed in the first, second, third, and fourth subfields. In the case of (b), light is intensively generated in the fifth subfield.

Then, in the case of the image frame of (a) and the image frame of (b), the gradation value is only one difference, but the difference in the amount of light generated by the actual discharge may be larger than the one gradation value.

Accordingly, when the image frames of (b) are continuously displayed after the image frames of the case (a) are displayed, noise such as pseudo contour noise is generated due to the difference in the intensity of light and the difference of the actual amount of light. Done.

In FIG. 7, the continuous gray values are used as the gradation values 15, 16, 17, and 18, but the discrete values are also used when the gradation values are 15, 20, 25, and 30. The same pseudo contour noise may occur at.

For example, at grayscale value 15, the first, second, third, and fourth subfields may be set as on subfields, and at grayscale value 20, the third subfield and the fifth subfield may be set as on subfields. In the gray value 20, the fifth subfield having a smaller number of on subfields than the gray value 15 but having a relatively large gray weight is set as the on subfield. Accordingly, even when the image frame of the grayscale value 15 and the image frame of the grayscale value 20 are continuously displayed, noise such as pseudo contour noise may occur as in the case of FIG. 7.

8A to 8B are diagrams for explaining a first embodiment of a method for reducing noise such as pseudo contour noise.

First, referring to FIG. 8A, the fifth subfield SF5 and the sixth subfield SF6 are set to on subfields in the case of the image frame of FIG.

Here, although the gray scale weight of the fifth subfield of the image frame of FIG. 7B is 16 and the gray scale weight of the sixth subfield is 32, the gray scale weight of FIG. 8A is higher than that of FIG. Is set smaller.

For example, in FIG. 8A, the case of (a) is referred to as the first image frame, the case of (b) as the second image frame, and the case of (c) is referred to as the third image frame. Here, the first image frame, the second image frame, and the third image frame may be continuous in time.

In addition, the gray scale weights of the subfields of the first image frame of (a) and the third image frame of (c) are 2 ⁿ (n = 0, 1) according to the arrangement order of the subfields as shown in FIG. , 2, 3, 4, 5, 6, 7).

Here, the sum of the gray scale weights of the on subfields of the first image frame of (a), that is, the gray scale value is called the first gray scale, and the gray scale value of the second image frame of (b) is called the second gray scale, (c Let gradation value of the third image frame be a third gradation. Here, the second grayscale is 16, which is larger than the first grayscale of 15, and the third grayscale is 17, which is larger than the second grayscale of 16.

Here, the fifth subfield of the first image frame of (a) is set to the gradation value 16 and the sixth subfield is set to the gradation value 32 as shown in FIG. 7, but the second image frame of (b) The fifth subfield distributes a portion of the gradation value 16 to the next subfield, that is, the sixth subfield. For example, the fifth subfield of (b) has a gray value 6, and the gray value 10 is distributed to the sixth subfield. Then, the sixth subfield does not have a gray value 32 as in (a) but has a gray value of 10 distributed by the fifth subfield.

Accordingly, the number of subfields disposed first in time of the first image frame (a), that is, the number of subfields arranged from the first subfield to the last subfield disposed in time, that is, the fourth subfield. Is the fourth, whereas the first subfield disposed in time of the second image frame of (b), i.e., the subfield disposed in time from the first subfield to the last subfield, i.e., up to 6 subfields The number of fields is six more than four in the preceding (a), and the first subfield disposed in time of the third image frame of (c), that is, the last subfield disposed in time from the first subfield. The number of fields, i.e. subfields up to 5 subfields, is more than 4 in the preceding (a) and less than 6 in (b).

Here, the sum of the gray scale weights of the fifth subfield of (b) and the gray scale weights of the sixth subfield may be substantially the same as the gray scale weight of the fifth subfield of (c).

In more detail, (b) the last sub-field disposed in time of the second image frame, that is, the eighth subfield and the first subfield disposed in time, that is, the last on-sub among the first subfield. The sum of the gray scale weights of the field, i.e., the subfield closest in time to the sixth subfield, i.e., the fifth subfield, and the gray scale weight of the last on subfield of this second image frame, i.e., the sixth subfield, It is preferable that the on-fields of the three image frames be substantially the same as the gray scale weight of the last subfield disposed in time, that is, the fifth subfield.

Here, the gray scale weights of the fifth subfield and the sixth subfield of the image frame of (b) may be different or may be the same. For example, as described above, the gray scale weight of the fifth subfield may be set to 6, and the gray scale weight of the sixth subfield may be set to 10.

Alternatively, the gray scale weight of the fifth subfield may be set to 8, and the gray scale weight of the sixth subfield may also be set to 8, which is the same as the fifth subfield. In more detail, the first subfield disposed in time of the second image frame of (b), that is, the subfield disposed last in time among the first subfield and the on subfield, that is, the subfield between the sixth subfield. The last subfield disposed among the fields, that is, the subfield closest in time to the sixth subfield, that is, the last subfield disposed in time among the gray scale weight of the fifth subfield and the on subfield of the second image frame, that is, the first subfield. The gray scale weights of the six subfields may be substantially the same.

Here, when the case of (b) is compared with the case of (c), it is preferable that the gray scale weight of the fifth subfield of (c) is larger than the gray scale weight of the sixth subfield of (b). In more detail, as in the foregoing case, the gray scale weight of the last subfield disposed in time in the on subfields of the second image frame of (b), that is, the sixth subfield is 8 or distributed from the fifth subfield. The gray scale weight of 10 is set to be smaller than the gray scale weight of the subfield disposed last in time, that is, the fifth subfield, of the on subfields of the third image frame of (c).

The gray scale weight may be determined in relation to the number of sustain signals supplied to the first electrode or the second electrode of the plasma display panel in the sustain period.

The change of the gray scale weight described above is compared with the number of the sustain signals as shown in FIG. 8B.

As shown in FIG. 8B, the fourth subfield of the first image frame of (a) and the third image frame of (c) may be supplied with a total of eight sustain signals in the sustain period as a gray scale weight of 8, and a fifth Suppose that a total of 12 sustain signals can be supplied in the sustain period as the subfield is gradation weight 16, and a total of 16 sustain signals can be supplied in the sustain period as the gradation weight 32 as the sixth subfield. Here, it is noted that the number of sustain signals set in FIG. 8B is arbitrarily determined for convenience of description.

On the other hand, in the fifth subfield of the second image frame of (b), a total of six sustain signals may be supplied with gray level weights of 8, and the six subfields also have a total of six sustain signals with gray level weights of 8. Can be supplied. That is, the sustain signal of the fifth subfield implementing the gray scale value 16 in (a) is distributed to the fifth subfield and the sixth subfield as in (b). As a result, the second image frame of (b) may implement the gray scale value 16.

Here, the subfield in which the sustain signal is indicated by a dotted line is an off subfield in the corresponding video frame, and the subfield in which the sustain signal is indicated by a solid line is an on subfield.

When the above method is used, light does not intensively occur in a specific subfield in the image frame of (b), but light is dispersed in the fifth and sixth subfields.

Accordingly, even when the video frame of (b) and the video frame of (a) are used successively, the concentration of light is eliminated, so that the generation of noise such as pseudo contour noise is reduced.

Next, FIG. 9 is a diagram for explaining a second embodiment of a method for reducing noise such as pseudo contour noise. Here, in FIG. 9, the description thereof will be omitted.

Referring to FIG. 9, gray level weights of the fifth subfield of the second image frame of (b) and the third image frame of (c) are distributed to the sixth subfield, which is the next subfield, as compared with the previous FIGS. 8A to 8B. do.

That is, in FIGS. 8A to 8B, the gray scale weight of a specific subfield is distributed to other subfields only between the first video frame of (a) and the second video frame of (b) to reduce noise such as pseudo contour noise. However, in FIG. 9, gray level weights of a specific subfield are distributed to other subfields between the video frames of (a) and (b) and between the video frames of (b) and (c), respectively, to form pseudo contour noise and the like. Noise can be further reduced.

As described above, the number of subfields for distributing gray scale weights may be variously changed.

10A to 10B are diagrams for explaining a third embodiment of a method for reducing noise such as pseudo contour noise. 10A to 10B, description thereof will be omitted.

First, referring to FIG. 10A, the dispersion direction of gray scale weights in the second image frame of (b) is different from those of FIGS. 8A to 8B and 9.

That is, in the foregoing FIGS. 8A to 8B and 9, the gray scale weights of the specific subfields are distributed to these specific subfields, for example, the other subfields adjacent to the fifth subfield, for example, the sixth subfield. The gray scale weight of the subfield, for example, the fifth subfield, can be distributed to this particular subfield, for example, the previous subfield, for example, the fourth subfield, adjacent to the fifth subfield, to further reduce noise such as pseudo contour noise. .

10A will be described with reference to the number of sustain signals as shown in FIG. 10B.

As shown in FIG. 10B, the third subfield of the first image frame of (a) and the third image frame of (c) may be supplied with a total of five sustain signals in the sustain period as a gray scale weight of 4, and further, a fourth Assume that the subfield may be supplied with a total of eight sustain signals in the sustain period as the gray scale weight 8, and the fifth subfield may be supplied with a total of 12 sustain signals in the sustain period as the gray subweight.

Here, it will be apparent that the number of sustain signals set in FIG. 10B is arbitrarily determined for convenience of description.

On the other hand, the fourth subfield of the second image frame of (b) may be supplied with a total of six sustain signals with a gray scale weight of 8, and a total of six sustain signals with a gray weight of 8 in the fifth subfield. Can be supplied. That is, the sustain signal of the fifth subfield implementing the gray scale value 16 in (a) is distributed to the fourth subfield and the fifth subfield as in (b). As a result, the second image frame of (b) may implement the gray scale value 16.

As described above, the dispersion direction of the gray scale weights of the specific subfield may be variously changed.

11A to 11B are diagrams for explaining a fourth embodiment of a method for reducing noise such as pseudo contour noise. Here, in FIG. 11A to FIG. 11B, the description thereof will be omitted.

First, referring to FIG. 11A, in the second image frame of (b), gray scale weights of a specific subfield are not biased in one direction and distributed in both directions, as compared with FIGS. 8A to 8B, 9 and 10A to 10B. Each can be distributed.

For example, in FIG. 11A, the gray scale weights of a particular subfield, for example, the fifth subfield, may be assigned to the previous subfield and the next subfield, such as the fourth subfield and the first subfield, which are adjacent to the particular subfield, for example, the fifth subfield. Dispersion into six subfields can further reduce noise such as pseudo contour noise.

11A will be described with reference to the number of sustain signals as shown in FIG. 11B.

As shown in FIG. 11B, a fourth subfield of the first image frame of (a) and the third image frame of (c) may be supplied with a total of eight sustain signals in the sustain period as a gray scale weight of 8, and a fifth Suppose that a total of 12 sustain signals can be supplied in the sustain period as the subfield is gradation weight 16, and a total of 16 sustain signals can be supplied in the sustain period as the gradation weight 32 as the sixth subfield.

Here, it is noted that the number of sustain signals set in FIG. 11B is arbitrarily determined for convenience of description.

On the other hand, the fourth subfield of the second image frame of (b) may be supplied with a total of three sustain signals with a gray scale weight of 4, and the fourth subfield also has a total of four sustain signals with a gray scale weight of 5. The sixth subfield may also be supplied with a total of five sustain signals with a gray scale weight of seven. That is, the sustain signal of the fifth subfield implementing the gray scale value 16 in (a) is distributed to the fourth subfield, the fifth subfield and the sixth subfield as in (b). As a result, the second image frame of (b) may implement the gray scale value 16.

As described above, the dispersion direction of the gray scale weights of the specific subfield may be set in a plurality of directions.

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.

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 device of the present invention reduces noise generation such as pseudo contour noise by distributing the gray scale weight of a specific subfield to these other subfields, and prevents deterioration of image quality of the image. It is effective.

Claims (7)

A plasma display panel for implementing an image using plasma discharge; A driver for realizing the gray level of the image by using a plurality of image frames including a plurality of subfields. Including, The plurality of image frames includes a first image frame, a second image frame, and a third image frame. The sum of gray level weights of the on subfields of the first image frame is a first gray level, The sum of gray level weights of the on subfields of the second image frame is a second gray level greater than the first gray level, The sum of gray level weights of the on subfields of the third image frame is a third gray level greater than the second gray level, The number of subfields from the first subfield disposed in time of the first image frame to the last subfield disposed in time in the on subfield is a first number, The number of subfields from the first subfield disposed in time of the second image frame to the last subfield disposed in time in the on subfield is a second number greater than the first number. The number of subfields from the first subfield disposed in time of the third image frame to the last subfield disposed in time in the on-field is less than the second number and is a third number greater than the first number. Plasma display device. The method of claim 1, And the on subfield is a subfield to which a data signal is supplied to the third electrode in an address period. The method of claim 1, And the first image frame, the second image frame, and the third image frame are continuous in time. The method of claim 1, The gray scale weight of the subfield disposed last in time among the on subfields of the second image frame is smaller than the gray scale weight of the subfield disposed last in time among the on subfields of the third image frame. Plasma display device. The method of claim 1, Gray scale weights of the subfields disposed closest to the last subfield disposed in the on-subfield among the subfields disposed last in time of the second image frame and the first subfield disposed in time, and the first gray level weights; The sum of the gray scale weights of the subfields disposed last in time among the on subfields of the second image frame is substantially the same as the gray scale weights of the subfields disposed last in time among the on subfields of the third image frame. Plasma display device. The method of claim 1, The gray scale weights of the subfields disposed closest to the last subfield among the subfields disposed between the first subfield disposed in time of the second image frame and the last subfield disposed in time of the on subfield; And gradation weights of the subfields disposed last in time among the on subfields of the second image frame are substantially the same. The method of claim 1, And a number of sustain signals supplied to at least one of the first electrode and the second electrode in the sustain period of the gray scale weight.

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