KR100612391B1 - Plasma display device and image processing method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display device and an image processing method thereof. More particularly, the present invention relates to a plasma display device and an image processing method thereof that compensate for distortion of a gray level caused by a minority error of the number of sustain pulses in each subfield.

According to the present invention, the number of sustain pulses applied in each sustain period is summed with the fractional error of the number of sustain pulses of the subfield having the same weight of the previous frame, and the gray scale generated by the fractional part error of the number of sustain pulses in each subfield. It is possible to improve the expressive power of gradation by compensating for the distortion of.

In addition, since the fractional part error of the number of sustain pulses of the low-weight subfield is not transmitted to the next frame, the fractional part error is spatially spread so that the flicker phenomenon does not appear on a low gray scale screen.

Plasma display, number of sustain pulses, fractional part error, gradation value, error diffusion

Description

Plasma display device and image processing method {PLASMA DISPLAY DEVICE AND IMAGE PROCESSING METHOD THEREOF}

1 is a timing diagram illustrating a method of driving a general plasma display device.

2 is a diagram illustrating an example of a method of generating the number of sustain pulses in each subfield in a frame.

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

4 is a block diagram schematically illustrating a sustain pulse number generator of a plasma display device according to an exemplary embodiment of the present invention.

5 is a block diagram schematically illustrating a method for generating the number of sustain pulses in each subfield in a frame according to an embodiment of the present invention.

Fig. 6 is a diagram showing an example of a method for generating the number of sustain pulses in each subfield in a frame according to the first embodiment of the present invention.

7 is a block diagram schematically illustrating a controller of a plasma display device according to a second embodiment of the present invention.

8 is a diagram showing an example of a method for processing fractional error of the number of sustain pulses in each subfield in a frame according to the second embodiment of the present invention.

9 is a diagram showing subfield data used in the fractional error processing method of the number of sustain pulses in each subfield in a frame according to the second embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display device and an image processing method thereof. More particularly, the present invention relates to a plasma display device and an image processing method thereof that compensate for distortion of a gray level caused by a minority error of the number of sustain pulses in each subfield.

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

1 is a timing diagram illustrating a method of driving a general plasma display device.

Referring to the drawing, the unit frame is divided into eight subfields SF1-SF8 to realize time division gray scale display. Each subfield SF1-SF8 is divided into a reset period R1-R8, an address period A1-A8, and a sustain period S1-S8.

In the reset period, the state of each discharge cell is initialized to smoothly perform the addressing operation on the discharge cells, and in the address period, the discharge cells that are turned on to select the discharge cells that are turned on and the discharge cells that are not turned on (addressed discharges). Cell wall) by applying an address voltage to the cell. In the sustain period, a sustain pulse is applied to perform discharge for actually displaying an image in the addressed discharge cell.

In general, in the address period, scan voltages are sequentially applied to the scan electrodes. When a scan voltage is applied to one scan electrode, an address voltage is selectively applied to the address electrode to address a desired discharge cell among all discharge cells. In the sustain period, an image is displayed by discharging the addressed discharge cells by applying sustain pulses to all scan electrodes and sustain electrodes.

The luminance of the plasma display device is proportional to the length of the sustain periods S1-S8 in the unit frame. The length of the sustain periods S1-S8 in the unit frame is 255T (T is the unit time). At this time, a time corresponding to 2n is set in the sustain period Sn of the nth subfield SFn. The n-th subfield has a weight value proportional to the length of the sustain period of the corresponding subfield. Accordingly, it is understood that when the subfield to discharge the discharge cells is appropriately selected from the eight subfields, display of 256 gray levels can be performed in all subfields including 0 (zero) gray that does not discharge the discharge cells. Can be.

However, when the image to be displayed on the plasma display device is overall bright, sustain pulses are continuously applied during each sustain period of each subfield, which consumes a lot of power.

Therefore, the sustain pulse is not continuously applied during the sustain period, and the number of sustain pulses of each subfield is adjusted according to the brightness of the screen. That is, the brightness of the image is judged as a load ratio proportional to the average gradation value of the entire screen, and when the load ratio is high, the number of sustain pulses in a frame unit is reduced, and conversely, when the load ratio is low, the number of sustain pulses in a frame unit is reduced. To increase.

At this time, if the number of sustain pulses in units of frames is determined according to the brightness of the image, the number of sustain pulses for each subfield is calculated according to a weight proportional to the sustain period length of the subfield.

In this case, the result of calculating the number of sustain pulses in each subfield has not only the integer part but also the fractional part as shown in FIG. However, since the number of sustain pulses is expressed only by the integer part, there is a problem that an error by the fractional part may occur in the gradation representation.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a plasma display device and an image processing method thereof, which compensate for a distortion of a gray level caused by a fractional part error in the number of sustain pulses in each subfield.

An image processing method of a plasma display device according to a feature of the present invention for achieving the above object

In the image processing method of the plasma display device which divides into a plurality of subfields corresponding to an input video signal of one frame, and displays a gray level according to a combination of these subfields,

(a) calculating the number of sustain pulses having an integer part and a fractional part assigned to each subfield of the current frame;

(b) calculating grayscale data corresponding to the fractional part of the number of sustain pulses allocated to a subfield having a weight less than a predetermined weight among the number of sustain pulses allocated to each subfield calculated in step (a);

(c) adding the gray scale data calculated in the step (b) to the gray scale data of the current frame of the discharge cell in which the subfield having the predetermined weight is less than the ON;

(d) spatially diffusing the grayscale data summed in the step (c).

In the method of calculating the gray scale data of the step (b), it is preferable to calculate the fractional part of the sustain pulse number by dividing the sustain pulse number per frame.

Plasma display device according to another aspect of the present invention

A plasma panel in which discharge cells are formed in an area where a plurality of address electrodes, a plurality of scan electrodes, and a sustain electrode cross each other;

The number of sustain pulses having an integer part and a fractional part assigned to each subfield of the current frame is calculated using the input video signal.

Gradation data corresponding to a fractional part of the number of sustain pulses allocated to a subfield having a weight less than a predetermined weight is calculated among the number of sustain pulses allocated to each of the calculated subfields,

Gradation data corresponding to the fractional part of the number of sustain pulses allocated to the subfield having a weight less than the predetermined weight is added to the current frame random gradation data of the discharge cell in which the subfield having the predetermined weight is less than the predetermined weight,

A controller configured to generate a control signal by spatially error spreading the sum grayscale data;

An address driver configured to apply a voltage to the address electrode according to a control signal generated by the controller; And

And a scan / hold electrode driver for driving the scan / hold electrode in accordance with a control signal generated by the controller.

The control unit,

A sustain pulse number generator for calculating a number of sustain pulses having an integer part and a fraction part assigned to each subfield of the current frame by using an input image signal;

Sustain pulse error conversion for calculating gradation data corresponding to the fractional part of the sustain pulse number assigned to a subfield having a weight less than a predetermined weight among the sustain pulse numbers assigned to each subfield calculated by the sustain pulse number generation unit. part; And

Corresponding to the fractional part of the number of sustain pulses allocated to the subfield having less than the predetermined weight in the grayscale data of the current frame of the discharge cell in which the subfield having the less than the predetermined weight calculated on the sustain pulse error converter is turned on. It is preferable to include an error diffusion unit that sums up the gray scale data and spatially spreads the sum of the gray scale data.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

A plasma display device and an image processing method thereof according to an embodiment of the present invention will now be described in detail with reference to FIGS. 3 to 8.

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

As shown in FIG. 3, a plasma display device according to an exemplary embodiment of the present invention includes a plasma panel 100, an address driver 200, a scan / hold driver 300, and a controller 400.

The plasma panel 100 includes a plurality of electrodes. The electrodes are arranged in a matrix of m × n. Specifically, address electrodes (hereinafter referred to as 'A electrodes') A1-Am are arranged in a column direction, and n rows of scan electrodes are arranged in a row direction. Hereinafter, the Y electrodes (Y1-Yn) and the sustain electrodes (hereinafter referred to as 'X electrodes') (X1-Xn) are arranged in a zigzag. Here, the discharge space at the intersection of the A electrodes A1-Am and the X and Y electrodes X1-Xn and Y1-Yn forms a discharge cell.

The address driver 200 receives an address driving control signal from the controller 400 and applies an address voltage for selecting discharge cells to be displayed to each address electrode A1-Am.

The scan and sustain driver 300 receives a control signal from the controller 400 and alternately applies a sustain pulse to the scan electrodes Y1-Yn and the sustain electrodes X1-Xn to perform sustain discharge for the selected discharge cell. do.

The controller 400 receives R, G, and B image signals and a synchronization signal from the outside, divides one frame into several subfields, and divides each subfield into a reset period, an address period, and a sustain period to drive the plasma display device. Generate a control signal. That is, the controller 400 generates a control signal for applying the address voltage and supplies it to the address driver 200. In addition, the controller 400 obtains the number of sustain pulses to be applied to each sustain period of the subfield in one frame, generates a control signal, and supplies the control signal to the scan / sustain driver 300.

At this time, the control unit 400 according to the embodiment of the present invention obtains the number of sustain pulses applied to each of the sustain periods. The fractional error of the number of sustain pulses of the subfield having the same weight of the previous frame is equal to the current frame. The sum is obtained by adding up the number of sustain pulses of a subfield having a weight.

Meanwhile, the controller 400 may add the fractional error of the number of sustain pulses of the low-weight subfield to convert the gray scale data into spatial data and then spread the error spatially.

4 is a block diagram schematically illustrating the sustain pulse number generator 460 of the plasma display device controller 400 according to the first exemplary embodiment of the present invention.

The sustain pulse number generator 460 includes a screen load ratio extractor 461, a sustain pulse number determiner 462 for each screen incubation rate, a sustain pulse number calculator 463 for each subfield, and a sustain pulse number adjuster 464. And a subfield information unit 465.

The screen load ratio extractor 461 extracts a load ratio proportional to the average gradation value of the entire screen from the image data. At this time, the load ratio is calculated by using the average value of the respective gradation values of all the discharge cells.

The sustain pulse number determiner 462 determines the number of sustain pulses per frame according to the load ratio extracted by the screen load ratio extractor 461. In this case, the sustain pulse number determiner 462 may store the number of sustain pulses per frame according to the load ratio in a table in advance, and determine the number of sustain pulses per frame using the stored table.

The subfield information unit 465 transmits the gray scale weight in each subfield to the sustain pulse number calculator 463 for each subfield. In this case, the subfield information unit 465 may store the grayscale weights in each subfield in a table in advance, and transmit the grayscale weights in each subfield to the sustain pulse number calculator 463 using the stored table. have.

The sustain pulse number calculator 463 for each subfield may be configured in each subfield based on the number of sustain pulses per frame determined by the sustain pulse number determiner 462 and the gray scale weight of each subfield received from the subfield information 465. Calculate the number of sustain pulses.

For example, the number of sustain pulses per frame is 1000, and the first gray level weights of the first to eighth subfields SF1 to SF8 are 1, 2, 4, 8, 16, 32, 64, and 128, respectively. The number of sustain pulses of the eighth subfield may be obtained by using Equation 1.

Here, Nsf (n) is the number of sustain pulses in the nth subfield, and Nfr is the number of sustain pulses per frame. Wsf (n) is the gray scale weight of the subfield of the nth subfield, and nmax is 8 in this embodiment.

The number of sustain pulses of the first to eighth subfields obtained using Equation 1 is 3.92, 7.84, 15.68, 31.37, 62.74, 125.49, 250.98, and 501.96, respectively. The operation sustain pulse number calculated in this way is composed of an integer part and a fractional part.

The sustain pulse number adjusting unit 464 adds the number of arithmetic sustain pulses calculated by the sustain pulse number calculating unit 463 for each subfield and the fractional part of the number of adjustment sustain pulses of the subfields having the same weight of the previous frame. Find the number of adjustment hold pulses. In addition, a constant part is taken from the number of adjustment sustain pulses to determine the number of applied sustain pulses.

5 is a block diagram schematically illustrating a method of generating a sustain pulse number in each subfield in a frame according to an embodiment of the present invention.

The sustain pulse number generation method is as follows. First, the gray scale values of all the discharge cells are first averaged from the image data to calculate a load ratio proportional to the average gray scale values of the entire screen (S110). Next, the number of sustain pulses per frame is determined according to the load ratio calculated in step S100 (S120).

Here, the number of sustain pulses in each subfield SF is calculated from the number of sustain pulses per frame and each gray scale weight in the current frame (S130). In this case, the number of sustain pulses in each of the subfields may be obtained using Equation 1.

Next, the number of adjustment sustain pulses in each subfield consisting of an integer part and a fractional part is obtained by adding the calculated sustain pulses in each subfield to the fractional part of the number of adjustment sustain pulses of the subfield having the same weight in the previous frame. Obtain In addition, the constant portion is taken from the number of adjustment sustain pulses to obtain the number of applied sustain pulses (S140). As many sustain pulses as the number of sustain pulses are applied to scan electrodes Y1-Yn and sustain electrodes X1-Xn.

In detail, in step S130, the number of sustain pulses in each subfield SF is calculated according to the gray scale weights from the number of sustain pulses per frame in the current frame. Here, the number of sustain pulses is the number of operational sustain pulses of each subfield in each frame, and the number of operational sustain pulses is divided into an integer part and a fractional part.

In Equation 1, the operation sustain pulse number Nsf (n) in each subfield SF is multiplied by the sustain pulse per frame Nfr and the weight Wsf (n) of each subfield, It is desirable to obtain the value by dividing the sum of the weights of all subfields in one frame. In this case, nmax is the number of subfields in one frame.

In the step S140, the number of adjustment sustain pulses is obtained by adding the number of operation sustain pulses in the current frame to the fractional part of the number of adjustment sustain pulses of the subfield having the same weight in the previous frame. At this time, the number of adjustment sustain pulses is composed of an integer part and a fractional part, similarly to the number of operation sustain pulses. It is calculated by adding up.

Referring to FIG. 6, an example of a method of generating the number of sustain pulses in each subfield in a frame according to the first embodiment of the present invention will be described.

In the current frame (N), the operation sustain pulse number of the first subfield SF1 is 18.8, the operation sustain pulse number of the second subfield SF2 is 20.2, and the number of operation sustain pulses of the third subfield SF3 The number of operation sustain pulses is 40.1.

In the previous frame ((N-1) frame), the number of adjustment sustain pulses of the first subfield is 10.6, the number of adjustment sustain pulses of the second subfield is 22.4, and the number of adjustment sustain pulses of the third subfield is 38.6. . At this time, the fractional part of the number of adjustment sustain pulses of the first subfield in the previous frame ((N-1) frame) is 0.6, the fractional part of the number of adjustment sustain pulses of the second subfield is 0.4 and the adjustment of the third subfield is performed. The fractional part of the sustain pulse number is 0.6.

Therefore, the number of adjustment sustain pulses of the first subfield in the current frame ((N) frame) is 18.8 + 0.6 = 19.4, the number of adjustment sustain pulses of the second subfield is 20.2 + 0.4 = 20.6, and the third subfield The number of adjustable hold pulses is 40.1 + 0.6 = 40.7.

Therefore, the number of applying sustain pulses of the first subfield in the current frame (N frame) is 19, which is an integer part of the number of adjustment sustaining pulses of the first subfield, and the number of applying sustain pulses of the second subfield is the second subfield. 20 is an integer part of the number of adjustment sustain pulses of the field, and 40 is an integer part of the number of adjustment sustain pulses of the third subfield.

At this time, the fractional part that is not reflected as the number of applied sustain pulses from the number of adjustment sustain pulses in the current frame ((N) frame) is combined with the number of operation sustain pulses in the same subfield of the next frame ((N + 1) frame) and The number of adjustment sustain pulses in each subfield of the frame ((N + 1) frame) is obtained.

As described above, the fractional part of the operation sustain pulse number which is not reflected by the applied sustain pulse number is reflected as the number of adjustment sustain pulses in the same subfield of the next frame, and thus it is timely felt by forming an average value in the same subfield of a temporally continuous frame. The gradation is closer to the gradation you want to express.

In the first embodiment of the present invention, since the number of sustain pulses is large in the sub-field having a high weight, even if the number of sustain discharge pulses is further increased, there is no problem in expressing gray scales. However, since the number of sustain discharge pulses is increased in the subfield having a low weight, when the number of sustain discharge pulses is further increased by adding the fractional part error portion, distortion may occur in the low gradation, and thus the gray scale to be displayed may not be represented. In a screen where the low subfield is mainly turned on, the change in the number of sustain pulses is relatively large due to the transmission of the next frame of the fractional part error, which may appear as flicker. The following describes how to solve this problem.

Next, a method of generating the number of sustain pulses in each subfield in a frame according to the second embodiment of the present invention will be described with reference to FIGS.

The second embodiment of the present invention is similar to the first embodiment, but the number of sustain pulses of the subfield having a high weight is summed with the fractional error of the number of sustain pulses of the subfield having the same weight of the previous frame, and the sub weight is low. The fractional error of the number of sustain pulses in the field is different in that it is converted into error gray scale data of the corresponding discharge cell to spread the error spatially.

7 is a block diagram schematically illustrating a controller of a plasma display device according to a second embodiment of the present invention.

The control unit of the plasma display device according to the second embodiment of the present invention includes a gamma correction unit 410, an error diffusion unit 420, a first subfield data generation unit 430, a memory control unit 440, and a second control unit. The subfield data generator 450, the sustain pulse error converter 470, the scan sustain drive controller 480, and the sustain pulse number generator 490 are included.

The gamma correction unit 410 maps the image data having the n-bit gradation value currently input to the inverse gamma curve and corrects the image data having the gradation value of m bits (m ≥ n). In this case, the image data input to the gamma correction unit 410 is a digital image signal. When the analog image signal is input to the plasma display device, the analog image signal may be converted into a digital image signal by an analog-to-digital converter (not shown). There is a need. The gamma correction unit 410 may include a lookup table (not shown) that stores data corresponding to an inverse gamma curve for mapping an image signal, or a logic circuit for generating data corresponding to the inverse gamma curve by a logical operation ( Not shown).

The second subfield data generator 450 generates subfield data corresponding to data of the upper n bits of the image data inversely gamma corrected by the gamma correction unit 410.

The sustain pulse number generator 490 compares the sustain pulse number generator 460 according to the first exemplary embodiment of FIG. 4 to the number of sustain pulses of a low-weight subfield having the same weight as the previous frame. The difference is that it does not add up to the fractional part of the number of sustain pulses in the field.

That is, the sustain pulse number generator 490 first extracts a load ratio proportional to the average gradation value of the entire screen from the image data output from the gamma correction unit 410. This can be obtained by averaging the respective gray scale values of all the discharge cells. In addition, the number of sustain pulses per frame is determined according to the load ratio. The number of sustain pulses in each subfield is calculated from the number of sustain pulses per frame and the gray scale weight of each subfield. The number of sustain pulses in each subfield can be obtained by using Equation 1.

In addition, the sustain pulse number generation unit 490 calculates the number of adjustment sustain pulses of the current frame by adding the calculated sustain pulse number and the fractional part of the number of adjustment sustain pulses of the subfield having the same weight of the previous frame. Here, the calculated sustain pulse number of the low-weight subfields (for example, the first and second subfields) does not sum with the fractional part of the adjusted sustain discharge pulse number of the subfield having the same weight of the previous frame. In addition, the sustain pulse number generation unit 490 takes an integer part from the number of adjustment sustain pulses to obtain the number of applied sustain pulses.

The sustain pulse error conversion unit 470 receives subfield data from the second subfield data generation unit 450, from the sustain pulse number generation unit 490, applied sustain pulse number data, and a subfield having a low weight. In the present embodiment, the fractional data of the number of sustain pulses calculated in the first and second subfields SF1 and SF2 is received.

The sustain pulse error converter 470 transmits the number of applied sustain pulses to the scan / maintenance drive control unit 480, and the fractional data of the number of operation sustain pulses of the low-weight subfield is obtained using the subfield data. After converting the data, the data is transmitted to the error diffusion unit 420.

The generation process of the error gray scale data will be described below. First, it is checked whether the low-weight subfields SF1 and SF2 are turned on in a predetermined discharge cell and adds all the fractional data of the number of operation sustain pulses of the on-low weight subfields SF1 and SF2. By dividing the added value by the number of sustain pulses per frame of the current frame, error grayscale data in the corresponding frame of the corresponding discharge cell can be obtained.

On the other hand, the sustain pulse error conversion unit 470 first turns on the fractional data of the number of operation sustain pulses of the low-weight subfields SF1 and SF2 divided by the number of sustain pulses per frame of the current frame, and then turns on the grayscale data. Gray level data of subfields SF1 and SF2 having a low weight may be added together.

The scan and sustain drive control unit 480 generates a control signal corresponding to the number of sustain pulses applied from the sustain pulse error converter 470 and outputs the control signal to the sustain and scan driver 300.

The error diffusion unit 420 includes image data having an m-bit gray scale value which is inversely gamma corrected by the gamma correction unit 410 and an error gray scale data (error) calculated by the sustain pulse error converter 470. Gradation value) are added up. Subsequently, data of lower m-n bits (m ≥ n) of the sum of the m-bit gradation values of the summed image data is error-diffused to surrounding discharge cells (pixels) to be converted into image data having the gradation value of n bits. do.

The error diffusion is a method of displaying the data for the lower bits as an image by separating the data for the lower bits from the image data to be error-spread and spreading them to adjacent discharge cells (pixels). 10-2002-0014766.

The first subfield data generator 430 generates subfield data corresponding to the image data having the n-bit grayscale value spatially error-diffused by the error diffusion unit 420.

The memory controller 440 rearranges the subfield data generated by the first subfield data generator 430 into address data for driving the plasma display device. In this case, the memory controller 440 separates all subfields of one frame into each subfield and stores them in a frame memory (not shown) for each subfield, and stores address data for all discharge cells in each subfield. Read from and send to the address driver.

8 and 9, a method of processing the fractional part error of the number of sustain pulses of the plasma display device control unit according to the second embodiment of the present invention illustrated in FIG. 7 will be described in detail.

The number of operation sustain pulses in the first to third subfields SF1 of the current frame (N frame) shown in FIG. 8 is 18.8, 20.2, and 40.1, respectively. The number of operation sustain pulses in the first to third subfields of the previous frame ((N-1) frame) is 10.6, 22.4, and 38.6, respectively. In addition, the fractional part of the number of adjustment sustain pulses of the third subfield of the previous frame ((N-1) frame) is 0.6.

Here, the fractional part of the number of adjustment sustain pulses of the third subfield of the previous frame ((N-1) frame) is summed up with the number of adjustment sustain pulses of the third subfield of the current frame ((N) frame). Therefore, the number of adjustment sustain pulses in the third subfield of the current frame ((N) frame) is 40.1 + 0.6 = 40.7.

In this manner, the fractional error of the number of sustain pulses of the high-weight subfield is processed by adding up the number of sustain pulses of the subfield having the same weight of the next frame.

Next, a process of converting the fractional part of the operation sustain pulse number of the low-weight subfield using the subfield data generated by the second subfield data generation unit 450 into error grayscale data will be described. 9 shows subfield data of all discharge cells in a predetermined frame. Here, 0 indicated in the subfield data indicates that the corresponding subfield is off, and 1 indicates that the corresponding subfield is on.

The operation sustain pulse of the low-weight subfields SF1 and SF2 turned on in the corresponding discharge cell is checked by referring to the subfield data to see whether the low-weight subfields SF1 and SF2 are turned on. Add up all the fractional data. By dividing the added value by the number of sustain pulses per frame of the current frame, error grayscale data in the corresponding frame of the corresponding discharge cell can be obtained.

Meanwhile, the process of converting the fractional part of the number of operation sustain pulses of the low-weight subfield into error gray data first maintains the fractional part data of the number of operation maintenance pulses of the low-weight subfields SF1 and SF2 per frame of the current frame. After dividing by the number of pulses and converting to grayscale data, the error grayscale data may be obtained by adding up grayscale data of the subfields SF1 and SF2 having low on-weights.

For example, the error gray scale data in the discharge cell 2 can be obtained as follows. Here, it is assumed that the number of sustain pulses per frame of the current frame is 1000, the sum of the weights of all subfields is 255, and the number of operation sustain pulses of the first to third subfields of the corresponding frame is 18.8, 20.2, and 40.1, respectively.

First, it is checked whether the first and second subfields in the discharge cell 2 are on. Further, the fractional part of the number of adjustment sustain pulses of the first and second subfields SF1 and SF2 is checked. Referring to FIG. 9, since both the first and second subfields SF1 and SF2 are turned on, 0.8, 0, and 2, which are fractional parts of the number of adjustment sustain pulses of the first and second subfields, are added. 1.0, which is the sum of 0.8, 0, and 2, is divided by 1000, which is the number of sustain pulses per frame of the current frame, to generate error grayscale data in the corresponding frame, and the error grayscale data is transmitted to the error diffusion unit 420.

Here, the error diffusion unit 420 adds the gamma correction data of the corresponding discharge cell (for example, the discharge cell 2) to the error grayscale data, and then spatially error-disperses the corresponding discharge cell.

In this manner, the fractional part error of the number of sustain pulses of the low-weight subfield is converted into error grayscale data of the corresponding discharge cell and then spatially diffused to process the error.

The second embodiment of the present invention does not add the fractional error portion of the number of sustain pulses of the subfield having the same weight of the previous frame to the number of sustain pulses of the low-weight subfield. Distortion is hard to occur. In addition, since the fractional error of the number of sustain pulses of the low-weight subfields SF1 and SF2 is not transmitted to the next frame, the fractional error is spatially spread so that the flicker phenomenon does not appear even in a low gray scale screen.

In the present embodiment, the low weight subfield is indicated as the first and second subfields, but the present invention does not limit the low weight subfield to the first and second subfields.

In addition, in the present embodiment, the sustain pulse error converter 470 generates error grayscale data and transmits the error grayscale data to the error diffuser 420. However, the present invention is not limited to the present embodiment, and the sustain pulse error converter is weighted. The fractional part data of the number of operation sustain pulses of the subfields of which is low is divided by the number of sustain pulses per frame of the current frame, converted into grayscale data, and then transmitted to the error diffusion unit, and the grayscale data of the low-weighted subfield in which the error diffusion unit is turned on You can add them all.

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

As described above, according to the present invention, the number of sustain pulses applied to each sustain period is summed with the fractional error of the number of sustain pulses of the subfield having the same weight of the previous frame, and thus the fractional part of the number of sustain pulses in each subfield. The expressive power of the gray scale can be improved by compensating for the distortion of the gray scale caused by the error.

In addition, since the fractional part error of the number of sustain pulses of the low-weight subfield is not transmitted to the next frame, the fractional part error is spatially spread so that the flicker phenomenon does not appear on a low gray scale screen.

Claims (17)

In the image processing method of the plasma display device which divides into a plurality of subfields corresponding to the video signal of each input frame, and displays the gray scale according to the combination of the subfields (a) calculating the number of sustain pulses having an integer part and a fractional part assigned to each subfield of each frame; (b) calculating, in the Nth frame, error grayscale data corresponding to the fractional part of the number of sustain pulses allocated to a subfield having a predetermined weight or less; (c) spatially spreading the error gray data; (d) Adjust and hold the number of fractions of the sustain pulse number of the subfield having the same weight in the N-1th frame to the number of sustain pulses allocated to the subfield having the predetermined weight or more in the Nth frame. Obtaining a pulse number; (e) in the Nth frame, applying the applied sustain pulse number corresponding to the integer part of the sustain pulse number calculated in the step (a) in the subfield less than the predetermined weight; And (f) In the Nth frame, applying the number of application sustain pulses corresponding to the integer part of the number of adjustment sustain pulses obtained in step (d) in the subfield equal to or greater than the predetermined weight. Way. The method of claim 1, Gamma correcting the video signal; And calculating the number of sustain pulses in the step (a) using the gamma corrected image signal. The method of claim 1, Measuring the load ratio of the video signal of each frame; And counting the number of sustain pulses in the step (a) using the load factor. The method of claim 1, Step (b) is, Calculating first gray scale data by dividing a fraction of the number of sustain pulses allocated to the subfield having the predetermined weight less than the total number of sustain pulses allocated to the Nth frame; And And obtaining the error grayscale data by adding the first grayscale data to the grayscale data of the discharge cells which are turned on among the subfields having a predetermined weight or less. The method of claim 1, Step (b) is, Obtaining first grayscale data which is the sum of the fractional parts of the subfields turned on among the fractional parts of the number of sustain pulses allocated to the subfield having the weight less than the predetermined weight; And And dividing the first grayscale data by the total number of sustain pulses allocated to the Nth frame to obtain the error grayscale data. delete delete delete delete A plasma panel in which discharge cells are formed in an area where a plurality of address electrodes, a plurality of scan electrodes, and a sustain electrode cross each other; The number of sustain pulses having an integer part and a fractional part assigned to each subfield of the current frame is calculated using the input video signal. Among the calculated sustain pulses allocated to each subfield, first grayscale data corresponding to a fractional part of the sustain pulses allocated to a subfield having a weight less than a predetermined weight is calculated; The first grayscale data is added to the grayscale data of the current frame of the discharge cell in which the subfield having the predetermined weight is less than one; A controller configured to generate a control signal by spatially error spreading the sum grayscale data; An address driver configured to apply a voltage to the address electrode according to a control signal generated by the controller; And A scan / hold electrode driving unit for driving the scan / hold electrode according to a control signal generated by the controller, And the control unit obtains the number of adjustment sustain pulses by adding the number of sustain pulses of the subfields having the predetermined weight or more with the fractional part of the number of sustain pulses of the subfields having the same weight in the previous frame. The method of claim 10, The control unit, A sustain pulse number generator for calculating a number of sustain pulses having an integer part and a fraction part assigned to each subfield of the current frame by using an input image signal; Sustain pulse error conversion for calculating gradation data corresponding to the fractional part of the sustain pulse number assigned to a subfield having a weight less than a predetermined weight among the sustain pulse numbers assigned to each subfield calculated by the sustain pulse number generation unit. part; And Corresponding to the fractional part of the number of sustain pulses allocated to the subfield having less than the predetermined weight in the grayscale data of the current frame of the discharge cell in which the subfield having the less than the predetermined weight calculated by the sustain pulse error converter is turned on And an error diffusion unit which sums up the gray scale data and spatially spreads the sum of the gray scale data. The method of claim 11, The sustain pulse number generation unit of the control unit, Obtains the number of sustain pulses per frame in the current frame according to the load ratio of the input video signal, The sustain pulse error converter of the controller, Gradation data is calculated by dividing the fractional part of the sustain pulse number by the sustain pulse number per frame. The method of claim 11, The sustain pulse number generation unit of the control unit, Obtains the number of sustain pulses per frame in the current frame according to the load ratio of the input video signal, The sustain pulse error converter of the controller, And a gray level data is calculated by dividing a value obtained by adding all the fractional parts of the number of sustain pulses of the current frame of the discharge cells turned on among the subfields having a predetermined weight less than the number of sustain pulses per frame. delete The method according to any one of claims 10 to 13, And the number of adjustment sustain pulses of each subfield below the predetermined weight is obtained from the number of sustain pulses of each subfield of the current frame. The method according to any one of claims 10 to 13, The number of sustain pulses applied to the discharge cells is calculated using the number of adjustment sustain pulses of the subfields. The method of claim 16, And the number of sustain pulses applied is an integer part of the number of adjustment sustain pulses.

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