KR20060096624A - The plasma display panel operating equipment and the methode of the same - Google Patents

Abstract

The present invention relates to an apparatus for driving a plasma display panel and a method of operating the same, wherein a halftone level of each cell in a block having a predetermined size in one frame has a same halftone level as a preset halftone level step. It is configured to include a driver for different subfield mapping according to the number, and the halftone level of all the cells in the block is set according to the number of cells having the same halftone level as a preset step in the block, thereby enabling more detailed grayscale expression. Therefore, the generation of gradation noise caused by the gradation expression restriction can be reduced.

Plasma Display Panel, PDP, Gray Noise, Subfield Mapping

Description

 Plasma display panel driving device and operating method thereof {The plasma display panel operating equipment and the methode of the same}

1 is a diagram showing a subfield period of a plasma display panel according to the prior art;

2 is a block diagram schematically showing a driving apparatus of a plasma display panel according to the prior art;

3 is a configuration diagram showing the configuration of the first embodiment of the plasma display panel driving apparatus according to the present invention;

FIG. 4 is a diagram illustrating a method for finding a region capable of generating grayscale noise in a specific frame in the plasma display panel according to the present invention;

5 is a flowchart illustrating a method of operating a plasma display panel driving apparatus according to the present invention.

<Explanation of symbols on main parts of the drawings>

110: halftone calculator 120: mapping unit

130: memory

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel driving apparatus and a method of operating the same. In particular, a region between 0 and 1 below the decimal point is divided into several levels of halftone levels, and the predetermined halftone level is determined in a predetermined size block. The present invention relates to a plasma display panel driving apparatus and a method of operating the subfield mapping of each cell according to the number of cells having the same halftone level.

The plasma display panel drives the corresponding pixel according to gray level data of the image. The plasma display panel expresses an image by dividing a plurality of subfields each including an address period and a discharge sustain period for each line of a frame.

In this case, the subfield may be grayed out according to the address period and the number of discharges for selecting a cell to be discharged by writing data such as a reset period for turning on the discharge evenly, or turning on or turning off the data. To achieve this, the cells are divided into sustain periods in which light is emitted simultaneously.

For example, assuming that 8 subfields are used in the plasma display panel, the gray level that can be expressed is at most 256 levels. Here, the reset period and the address period (a) of each subfield are the same, but the sustain period (b) is 2 ⁿ (n = 0, 1, 2, 3, 4, 5, 6, 7) will increase.

Therefore, in each subfield, the intensity (applied voltage) of each sustain signal is equal to the amount of light emitted per hour. Therefore, when the sustain period (pulse width) is increased, the screen brightness seen by the human eye appears bright in proportion to the sustain period. The gray level can be expressed by subfields.

To this end, as shown in FIG. 2, the apparatus for driving a plasma display panel according to the related art includes an inverse gamma correction unit 10, an error diffusion unit 20, and a subfield mapping for gray scale expression, into which an image signal is input. It comprises a unit 30 and a data alignment unit 40.

The inverse gamma correction unit 10 inversely gamma corrects an input image signal and linearly converts luminance values according to grayscale values of the image signals to match the characteristics of the plasma display panel.

In general, since the inverse gamma correction unit 10 performs 2.2 gamma processing, when the value input to the inverse gamma correction unit is 20 or less, the inverse gamma correction unit 10 is expressed as a decimal point value of 1 or less, so that the screen is digitally displayed as described above. In the apparatus, the value below the minimum representable gradation level 1 cannot be expressed.

To this end, the error diffusion unit 20 expresses a halftone between 0 and 1 by finely adjusting luminance values between adjacent cells in a unit pixel area. As described above, in order to finely adjust the luminance value between adjacent cells, an error value is calculated through the difference between the input original signal value and the value of the gradation correction after the value below the decimal point is removed, and the error value is added to or subtracted from the original signal. As the calculated error value is diffused to an adjacent cell, the halftone is expressed.

The subfield mapping unit 30 separates the data output from the error diffusion unit 20 to perform subfield mapping according to the luminance relative ratio, and the data alignment unit 40 applies image data according to the characteristics of the plasma display panel. Arrange the order.

As described above, the conventional method of expressing the intermediate gray scale by error diffusion has a problem in that grayscale noise occurs due to error diffusion, and grayscale patterns such as bands are generated on the screen.

In addition, the actual plasma display panel product has a disadvantage that it is difficult to express the desired gray scale level because it is limited to express the gray scale level that can be expressed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and divides an area between 0 and 1 below the decimal point into several levels of halftone, and is equal to the preset halftone level in a block of a predetermined size. According to the present invention, there is provided a plasma display panel driving apparatus and an operation method thereof, by which subfield mapping of each cell is performed differently according to the number of cells having a halftone level, thereby reducing grayscale noise.

The plasma display panel driving apparatus according to the present invention for solving the above problems is a cell having a halftone level equal to a preset halftone level step of each cell in a block having a predetermined size in one frame. Characterized in that it comprises a drive unit for different subfield mapping according to the number of.

In addition, the operating method of the driving apparatus of the plasma display panel according to the present invention is the number of cells in which the halftone level is not the integer level represented by each cell in the block having a predetermined size in one frame and the same halftone level is preset. Depending on the subfield mapping is characterized in that.

Hereinafter, a plasma display panel driving apparatus of the present invention will be described with reference to the accompanying drawings. 3 is a block diagram showing the configuration of the first embodiment of the plasma display panel driving apparatus according to the present invention, Figure 4 is a method for finding a region capable of generating grayscale noise in a specific frame in the plasma display panel according to the present invention It is done.

In the plasma display panel driving apparatus of the present invention, as shown in FIG. 3, a cell having a halftone level having the same halftone level as a preset halftone level step in each cell in a block having a predetermined size in one frame. The driving unit 100 may perform different subfield mappings according to the number of.

To this end, the driving unit 100 calculates the number of cells in which the halftone level of each cell in the block having a predetermined size in one frame has the same halftone level as the preset halftone level step. And 110.

In general, the plasma display panel may express gray scales of up to 256 levels when eight subfields SF0 to SF7 are used. In this case, since the plasma display panel expresses an gradation level having an integer value from the 0 level to the 255 level, an intermediate gradation level expression having a value between 0 and 1 is required for more natural gradation representation.

The driving unit 100 divides the area between 0 and 1 into several steps, and calculates the number of cells in which the halftone level required to be expressed in each cell in the block is the same as the preset step, wherein the block is 2 * 1 or more. Has a size.

When the plasma display panel driving apparatus of the present invention further comprises a memory unit 130 storing the halftone level of each cell, the halftone level of each cell in the block while the count calculator 110 is driven. Is stored in the memory unit.

For example, assuming that the block size is 4 * 2 and the preset halftone level step is set to 0, 1/2, and 1, the number calculating unit 110 has the same halftone level as the set halftone level. The number of cells having a level is calculated.

As shown in FIG. 4, when the intermediate gray level of each cell in the block is 0, 0, 1, 1, 0.5, 1, 0, 0, the number calculating unit 110 has a cell having a zero gray level. It is calculated that there are four silver, one cell having a half-level halftone, and three cells having a half-level halftone.

The driving unit 100 performs subfield mapping according to the number of cells having the same halftone level as the preset halftone level calculated by the number calculating unit 110. The method further includes a mapping unit 120 for subfield mapping differently when the number of cells having the same halftone level is greater than or equal to the reference value.

That is, the mapping unit 120 according to the calculation result of the number calculating unit 100, so that the number of gray scales that can be expressed than when the number of cells having the same halftone level as the preset halftone level step is greater than or equal to the reference value is less than Perform subfield mapping.

In the above example, when the reference value is set to four, since the block has four cells having zero levels, the block is subfield mapped to increase the number of gray levels that can be expressed, and when the reference value is set to five, the block is Since the maximum number of cells having the same intermediate gradation is four, subfield mapping with a small number of gradations that can be represented is performed.

In the case of a typical plasma display panel, due to circuit complexity and capacity limitation, 256 levels of gray levels are represented through 100 or less subfield mappings. In this case, gray level noise is generated due to the limitation of the number of available subfield mappings. .

However, when the number of cells having the same halftone level as the preset halftone level step is greater than or equal to the reference value as described above, when the subfield mapping is performed so that the number of grayscales that can be expressed is greater than the following, the preset halftone level step on the same screen is performed. If the number of cells having the same gradation level is equal to or greater than the reference value, the subfield mapping with a large number of representable gradations is performed, and the region other than the gradation noise is removed by performing subfield mapping according to the existing subfield mapping method. A cleaner, more natural picture can be displayed without increasing circuit complexity and capacity.

In this case, as shown in FIG. 3, the driving unit 100 further includes a halftone setting unit 140 that sets a halftone level of each cell in the block according to the calculation result of the number calculator 110. Can be configured.

If the number of cells having the same halftone level as the preset halftone level is greater than or equal to the reference value, the halftones of all the cells of the block are set to be the same, and the halftones of all the cells of the block are the maximum halftone cells. Level, and in the opposite case, the cells in the block maintain the conventional halftone level.

In the above example, if the reference value is set to four, the block has four cells having a zero level, so that the entire block is set to zero level having a maximum number of four cells having the same intermediate gray level. In this case, the block maintains a conventional halftone level so that each cell has a halftone level of 0, 0, 1, 1, 0.5, 1, 0, and 0, respectively.

The driver 100 sequentially moves from the upper left side to the lower right side of the plasma display panel to generate blocks to perform subfield mapping according to the number of cells having the same halftone level as the preset halftone level.

In this case, when the number of cells having the same halftone level as the preset halftone level step is greater than or equal to the reference value, a cell having a high probability of generating grayscale noise is a cell having the same halftone level as the preset halftone level step as described above. When the number of times is greater than or equal to the reference value, when the subfield mapping is performed so that the number of gray scales that can be expressed becomes larger than the following, gray level noise can be eliminated.

When the halftone level step is subdivided, it is easy to calculate a grayscale noise generation area, preferably 0, 1/16, 2/16,... , 15/16, 1 shall be set.

For example, the block size is 4 * 2, the preset halftone level level is divided between 0 and 1 into 16 steps, and the halftone level of each cell in the block is 1/16, 0, 4/16, respectively. Suppose that is set to 7/16, 1/16, 0, 1/16, 5/16.

The number calculating unit 110 calculates the number of cells having the same halftone level level as the set halftone level, and two cells having a halftone of zero level and cells having a halftone of 1/16 level. It is calculated that 3 cells, 1 cell having a halftone of 4/16, 5/16 and 7/16 levels, respectively.

The halftone setting unit 140 sets the halftone level of each cell in the block according to the result of the number calculating unit 110. If the reference value is set to three, the block has a 1/16 level cell. Since there are three cells, all cells in the block are set to have a halftone of 1 / 16th level.

In contrast, when the reference value is set to four or more, the block has the maximum number of cells having the same halftone, so that each cell of the block maintains the existing halftone.

The mapping unit 120 performs subfield mapping so that the number of available expressive numbers is greater than the case where the number of cells having the same halftone level as the preset halftone level is greater than or equal to the reference value. If the number of cells having the same halftone level is equal to or greater than the reference value, the halftones of all the cells in the block are set to be the same. Subfield mapping is performed in which the number of gradations that can be expressed is greater than that in the case.

That is, since grayscale noise occurs when the number of grayscales that can be expressed is small, the subfield mapping of each cell in the block according to the number of cells having the same halftone level as the halftone level step set in the above-described block. As this is performed differently, possible gradation noise can be reduced.

5 is a flowchart illustrating an operating method of a driving apparatus of a plasma display panel according to the present invention. Referring to FIG. 5, a method of operating the plasma display panel driving apparatus of the present invention will be described.

In the method of operating the plasma display panel driving apparatus of the present invention, a subtone level, which is not an integer level represented by each cell in a block having a predetermined size in one frame, is sub-subjected according to the number of cells having the same level as the preset halftone level. The field mapping is done differently.

To this end, first, in the first step, the number of cells in which the halftone level represented in each cell in the block is equal to the preset halftone level step is calculated.

At this time, the number of cells of the halftone level represented in each cell in the block is equal to the preset halftone level step (S1), and the number of cells having the same halftone level as the preset halftone level step is calculated. Accordingly, the halftones of each cell in the block are set (S4 and S6).

If the number of cells required for the representation of each cell in the block and the number of cells equal to the preset level of halftone level is greater than or equal to a predetermined reference value (S2), the halftone level of all the cells in the block is the preset halftone level. The same number of cells as the step is set to the maximum halftone level (S3), and otherwise, the cells in the block maintain the existing halftone level (S4).

In this case, the block has a size of 2 * 1 or more.

In the second step, the subfield mapping is performed differently when the number of cells of the halftone level represented by each cell in the block is not equal to or greater than a reference value as the preset halftone level step (S5 and S6).

In this case, the preset halftone level step should be set to two or more levels, preferably set to divide the area between 0 and 1 in 16 steps, and sequentially from the upper left side of the panel to the lower right side in one frame. As the block is generated, the subfield mapping is performed according to the halftone level of the cells in the block.

Therefore, one screen is divided into a plurality of blocks, and the halftone level represented by each cell inside the block is compared by comparing the halftone level required with the required halftone level of all cells in each block. When the number of cells equal to the preset halftone level step is greater than or equal to the reference value, the number of subfield mappings that can be expressed is greater than that of the following cases.

In particular, when the halftones of the cells inside the block are determined by the number of cells having the same halftone level as the preset halftone level step, the subfield mapping is determined according to whether the halftones of all the cells in the block are the same. It can be done differently.

That is, the subfield mapping is performed so that the number of gray scales that can be expressed in all the cells in the block is the same as compared to the case where the cells are not identical. It is possible.

As described above, the apparatus for driving a plasma display panel and a method of operating the same according to the present invention have been described with reference to the illustrated drawings. However, the present invention is not limited by the embodiments and drawings disclosed herein, and the technical spirit of the present invention is protected. It can be applied by those skilled in the art within the range to be.

The plasma display panel driving apparatus and its operation method according to the present invention configured as described above divide an area between 0 and 1 below the decimal point into several levels of halftones, and in the block having a predetermined size, the preset halftones The subfield mapping is different according to the number of cells having the same halftone level as the level, so that the number of cells having the same halftone level equal to the preset halftone level is greater than or equal to the reference value, the subfield mapping having a greater number of expressed grayscales than the case below As a result, the grayscale noise can be eliminated.

Claims (15)

The halftone level of each cell in the block having a predetermined size in one frame is configured to include a driver for differently subfield mapping according to the number of cells having the same halftone level as the preset halftone level level. A plasma display panel drive device. The method of claim 1, And the driving unit performs subfield mapping differently when the number of cells having the same halftone level as the preset halftone level is greater than or equal to a reference value. The method of claim 1, When the number of cells having the same halftone level as the preset halftone level step is greater than or equal to the reference value, the driving unit may express more grayscales when the number of cells having the same halftone level as the preset halftone level step is less than or equal to the reference value. Plasma display panel drive apparatus characterized in that the sub-field mapping so that the number increases. The method of claim 1, The driving unit further comprises a halftone setting unit for setting the halftone level of each cell in the block. The method of claim 4, wherein And the driving unit performs subfield mapping so that the number of gray scales that can be expressed is greater than when the middle gray levels of the cells in the block are the same. The method of claim 1, In the preset halftone level step, an area between 0 and 1 has 16 steps. The method of claim 1, The driving unit further comprises a memory unit for storing the halftone level of each cell. The method of claim 1, And the block size is 2 * 1 or more. The method of claim 8, The driver generates blocks by sequentially moving from the upper left to the lower right of the plasma display panel to calculate the number of cells having the same halftone level as the halftone level and the preset halftone level of each cell in the block. Plasma display panel drive device characterized in that. Plasma display panel, characterized in that the sub-field mapping is different according to the number of cells in which the halftone level, not the integer level represented in each cell in the block having a predetermined size in one frame, is equal to the preset halftone level. Method of operation of the drive. The method of claim 9, The method of operating the plasma display panel driving apparatus includes: a first step of calculating the number of cells having the same halftone level as the preset halftone level represented by each cell in the block; And a second step of differently performing subfield mapping when the number of cells having the same halftone level as the preset halftone level is not equal to or greater than a reference value. Operation method of display panel drive device. The method of claim 11, The first step is to match the halftone level of the entire block to the halftone level having the greatest number of halftone levels when the number of cells having the same halftone level and the preset halftone level of each cell in the block is greater than or equal to the reference value. Method of operating a plasma display panel drive device comprising a process. The method of claim 12, The first step is a method of operating a plasma display panel driving apparatus, characterized in that the block is sequentially generated from the upper left to the lower right of the panel in one frame. The method of claim 12, And the size of the block is 2 * 1 or more. The method of claim 12, In the second step, the number of gradations that can be expressed is increased more than the case where the number of cells of the intermediate gradation level expressed in each cell in the block is equal to or less than a reference value is equal to or less than a reference value. Operation method of splay panel drive device.

Images