KR100864519B1 - Plasma Display Device Driving Method - Google Patents

Abstract

A plasma display device driving method according to the present invention includes a first step of converting RGB image data into grayscale data, a second step of detecting an edge region by applying a mask having a multiplication coefficient value to the grayscale data, and the edge region. Comprising a third step of correcting the pixel gradation of the edge region by varying the compensation value according to the relative brightness of the, and the effect of correcting the outline of the object and the edge region of the object and the background of the object and the background and output a clear image It is possible to output a more three-dimensional image. In addition, there is an effect of improving the image quality and the visual fatigue by improving the recognition and discrimination of the background and objects.

Plasma display device, edge, tempered, sharpening

Description

 Plasma Display Device Driving Method

1 is a view showing an embodiment of the structure of a plasma display device;

2 illustrates an embodiment of an electrode arrangement of a plasma display device;

3 is a diagram illustrating an embodiment of a method in which a frame of an image is time-divided and driven into a plurality of subfields in a plasma display device;

4 is a flowchart illustrating a plasma display device driving method according to the present invention;

5 is a view illustrating a pixel to which a mask is applied in the plasma display device driving method according to the present invention;

Figure 6a is a view showing a mask used in the plasma display device driving method according to the present invention,

6B is a view illustrating a pixel corresponding to a mask in the plasma display device driving method according to the present invention;

FIG. 7 is a diagram illustrating a boundary line and an edge area of an object and a background in an image;

8A is a diagram illustrating an embodiment of a mask to which a plasma display device driving method according to the present invention is applied;

8B and 8C are diagrams illustrating an embodiment of grayscale data of an image to which the plasma display device driving method according to the present invention is applied;

9 is a graph showing a compensation value according to an input gray level in the plasma display device driving method according to the present invention;

10A is a view showing an original image to which the plasma display device driving method is not applied according to the present invention;

FIG. 10B is a diagram illustrating an image having gray level compensation applied to the plasma display device driving method according to the present invention.

<Explanation of symbols on main parts of the drawings>

10: upper substrate 11: scan electrode

12: sustain electrode 15: black matrix

20: lower substrate 21: partition wall

22: address electrode 23; Phosphor

24: lower dielectric layer 210: background

220: edge region 230: boundary line

240: object P (i, j): gradation data

M (i, j): Multiplication coefficient of the mask

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a plasma display device, and more particularly, to a method for driving a plasma display device for improving image recognition power by clearing a boundary portion of an image output to a panel.

In general, a plasma display device receives an RGB image signal photographed with a camera and displays it in a plan view. In this case, since the boundary between the background of the image and the object is not clear, the image recognition power of the screen is inferior to the viewer. In particular, when a moving screen is output, a background image and an image of an object are scattered, resulting in a drop in three-dimensional feeling and a perception of the object. Also, there is a problem in that eye fatigue is easily felt.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to provide a plasma display device driving method for detecting an edge region of an image output to a panel and then improving and outputting the edge region of the image. .

The plasma display device driving method according to the present invention for solving the above problems is a first step of converting the RGB image data to the grayscale data, and applying a mask having a multiplication coefficient value to the grayscale data to detect the edge region; And a third step of correcting pixel gradation of the edge area by varying a compensation value according to the relative brightness of the edge area.

Here, in the second step, a multiplication process of multiplying the grayscale data of the center pixel and neighboring pixels to be processed by the multiplication coefficient value of the mask, and adding up the multiplied values obtained in the first process to calculate a result value And an edge discrimination process of comparing the result value with a predetermined reference value to determine whether the center pixel belongs to an edge region.

In addition, the edge discrimination process determines the first edge area when the result value is equal to or less than the -reference value, and determines the second edge area when the result value is equal to or greater than the + reference value. If the value is between the -reference value and the + reference value, it is determined that it is not an edge region.

The third step may reduce the gray level of the center pixel by the compensation value when the center pixel corresponds to the first edge area.

In the third step, when the center pixel corresponds to the second edge area, the gray level of the center pixel is increased by the compensation value.

Here, the compensation value is set differently according to the basic gray level of the center pixel.

The compensation value may be set differently for each gradation group by dividing the entire gradation into at least two gradation groups according to the gradation order.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a view showing an embodiment of the structure of a plasma display device.

Referring to FIG. 1, the plasma display apparatus includes a scan electrode 11 and a sustain electrode 12, which are sustain electrode pairs formed on the upper substrate 10, and an address electrode 22 formed on the lower substrate 20. It includes.

Each of the sustain electrode pairs 11 and 12 is typically a transparent electrode 11a or 12a formed of indium tin oxide (ITO), a metal such as silver (Ag), chromium (Cr), or chromium / copper. And the bus electrodes 11b and 12b which may be formed in a stack of / chromium (Cr / Cu / Cr) or in a stack of chromium / aluminum / chromium (Cr / Al / Cr). At this time, the bus electrodes 11b and 12b are formed on the transparent electrodes 11a and 12a to reduce the voltage drop caused by the transparent electrodes 11a and 12a having high resistance.

In addition, the PDP has a function of light blocking to reduce the reflection and absorption of external light generated from the outside of the upper substrate 10, and to improve the purity of the upper substrate 10 and the contrast of the PDP. Black Matrix (BM) is formed.

The black matrix is formed between the first black matrix 15 formed at a position overlapping the partition wall 21 formed on the lower substrate 20, between the transparent electrodes 11a and 12a and the bus electrodes 11b and 12b. It is composed of the second black matrices 11c and 12c formed. As such, the black matrix formed by separating the first and second black matrices 15, 11c and 12c is called a separate type BM, and since the second black matrices 11c and 12c form a layer between the electrodes, the black matrix is black. It may also be called a layer or a black electrode layer.

An upper dielectric layer 13 and a protective layer 14 are stacked on the upper substrate 10 on which the scan electrode 11 and the sustain electrode 12 are formed, respectively, and charged particles in which plasma is generated are accumulated in the upper dielectric layer 13. . The protective layer 14 protects the upper dielectric layer 13 from sputtering of charged particles generated during gas discharge, and increases emission efficiency of secondary electrons.

In addition, the address electrode 22 is formed on the lower substrate 20 in a direction crossing the scan electrode 11 and the sustain electrode 12, and the lower dielectric layer 24 is formed on the lower substrate 20 on which the address electrode 22 is formed. ) And a partition wall 21 are formed, and phosphors 23 which emit light by ultraviolet rays generated during gas discharge and generate visible light are coated on the lower dielectric layer 24 and the partition wall 21.

The partition wall 21 includes a vertical partition wall 21a formed in a direction parallel to the address electrode 22 and a horizontal partition wall 21b formed in a direction crossing the address electrode 22 to physically distinguish discharge cells. Ultraviolet rays and visible light generated by the discharge are prevented from leaking to the adjacent discharge cells.

Since the structure of the panel shown in FIG. 1 is only an embodiment of the structure of the plasma display device according to the present invention, the present invention is not limited to the structure of the plasma display device shown in FIG. 1. For example, the PDP according to the present invention may have a structure in which each of the sustain electrode pairs 11 and 12 omits the transparent electrodes 11a and 12a made of ITO and includes only the bus electrodes 11b and 12b. Since the structure does not use the transparent electrodes 11a and 12a, there is an advantage of lowering the unit cost of panel manufacturing, and the bus electrodes 11b and 12b may be various materials such as photosensitive materials in addition to the materials listed above.

In addition, the partition structure of the PDP shown in FIG. 1 represents a close type in which the discharge cells are closed by the vertical partition 21a and the horizontal partition 21b, but the present invention is not limited thereto. The exhaust passage is provided in at least one of the stripe type, which is the omitted structure, the differential partition structure having a different height between the vertical partition 21a and the horizontal partition 21b, the vertical partition 21a or the horizontal partition 21b. A channel type barrier rib structure in which a usable channel is formed, a groove type barrier rib structure in which a groove is formed in at least one of the vertical barrier rib 21a or the horizontal barrier rib 21b, and the like may be used.

Here, in the case of the differential barrier rib structure, the height of the horizontal barrier rib 21b is more preferable, and in the case of the channel barrier rib structure or the groove barrier rib structure, it is preferable that the channel is formed in the horizontal barrier rib 21b or the groove is formed. something to do.

On the other hand, in one embodiment of the invention is shown and described that each of the R, G and B discharge cells are arranged on the same line, it may also be arranged in other formation. For example, a delta type arrangement in which R, G, and B discharge cells are arranged in a triangular shape may be possible, and the shape of the discharge cell may be not only square but also various polygonal shapes such as pentagon and hexagon.

2 is a view showing an embodiment of the electrode arrangement of the plasma display device.

Referring to FIG. 2, it is preferable that a plurality of discharge cells constituting the plasma display device are arranged in a matrix form. The plurality of discharge cells are provided at the intersections of the scan electrodes Y1 to Ym, the sustain electrodes Z1 to Zm, and the address electrodes X1 to Xn, respectively. The scan electrodes Y1 to Ym may be driven sequentially or simultaneously, and the sustain electrodes Z1 to Zm may be driven simultaneously. The address electrodes X1 to Xn may be driven by being divided into odd-numbered and even-numbered electrodes or sequentially driven.

2 is only an embodiment of the electrode arrangement of the plasma display device according to the present invention, the present invention is not limited to the electrode arrangement and driving method of the plasma display device shown in FIG. For example, a dual scan method in which two scan electrodes of the scan electrodes Y1 to Ym are simultaneously scanned is possible, and the address electrodes X1 to Xn are divided up and down at the center of the panel. It may be driven.

3 is a diagram illustrating an embodiment of a method in which a frame of an image is time-divided and driven into a plurality of subfields in a plasma display device.

Referring to FIG. 3, referring to FIG. 3, a unit frame may be time-division driven into a predetermined number, for example, eight subfields SF1,..., SF8 to express the gray level of an image. Each subfield SF1, ..., SF8 is divided into a reset section (not shown), an address section A1, ..., A8, and a sustain section S1, ..., S8. .

In each address section A1, ..., A8, a data signal is applied to the address electrode X, and corresponding scan pulses are sequentially applied to each scan electrode Y. FIG. Sustain pulses are alternately applied to the scan electrode Y and the sustain electrode Z in each of the sustain periods S1, ..., S8, so that the discharge cells selected in the address periods A1, ..., A8 are alternately applied. Cause sustain discharge.

The luminance of the plasma display device is proportional to the number of sustain discharges in the sustain periods S1, ..., S8 occupied in the unit frame. When one frame forming one image is represented by eight subfields and 256 gray levels, each subfield in turn has different sustain pulses at a ratio of 1, 2, 4, 8, 16, 32, 64, and 128. The number of can be assigned. Alternatively, in order to obtain luminance of 133 gray levels, cells may be sustained by addressing cells during subfield 1, subfield 3, and subfield 8 sections.

Meanwhile, the number of sustain discharges allocated to each subfield may be variably determined according to the weights of the subfields. That is, in FIG. 3, a case in which one frame is divided into eight subfields has been described as an example. However, the present invention is not limited thereto, and the number of subfields forming one frame may be variously modified according to design specifications. . For example, the plasma display apparatus may be driven by dividing one frame into eight or more subfields or the like, such as 12 or 16 subfields.

4 is a flowchart illustrating a method of driving a plasma display device according to the present invention, and FIG. 5 is a view illustrating a pixel to which a mask is applied in the method of driving a plasma display device according to the present invention.

The plasma display apparatus receives an analog RGB video signal from the outside and converts the analog RGB video signal into a digital RGB video signal using an A / D converter. The digital RGB image signal includes color information, saturation information, and brightness information.

The plasma display device driving method according to the present invention first detects an edge region in an image. As a method of detecting the edge region, various methods may be used. Here, a method of detecting an edge region using a mask is described, but the present invention is not limited thereto and may be performed by other methods.

Before the mask is applied, the digital RGB image signal is first converted into grayscale data (S100). In other words, the RGB color signal is converted into a Y signal which is a black and white signal having only brightness information. This is for detecting edges and detecting edge regions in an image using brightness information except color information.

Referring to FIG. 5, a color image is converted into a black and white image having grayscale data and a mask is applied (S110). Pixels 1 to 9 of FIG. 5 are pixels to which a mask is to be applied, and a mask is applied to the center pixel and its surrounding pixels.

In FIG. 5 and the method described below, a mask having a size of 3 × 3 is used as an example.

6A illustrates a mask used in the plasma display device driving method according to the present invention, and FIG. 6B illustrates a pixel corresponding to the mask in the plasma display device driving method according to the present invention.

Referring to Fig. 6A, the mask has a multiplication coefficient value for the pixels of each row and column. The multiplication coefficient of the center pixel is called M (i, j), and the multiplication coefficient of the surrounding pixels is stored in a matrix format based on the position i, j.

The grayscale data of the image corresponding to the center pixel of the mask may be represented as P (i, j) as shown in FIG. 6B. The remaining peripheral pixels are also defined as shown in FIG. 6B based on the position i, j of the pixel.

The mask is applied from the first pixel to the last pixel of the image to detect the edge area. FIG. 7 is a diagram illustrating a boundary line and an edge region of an object and a background in an image, and illustrates an example of an image having a human shape. The object 240 is positioned inside the background 210, and detects an edge region 220 formed of left and right pixels based on the outline or boundary line 230.

In general, the brightness value, that is, the gray scale data, is different based on the boundary line 230 in the image. That is, the contrast between the inside and the outside of the boundary is relatively different. In the present invention, the mask is applied to detect the edge region 220 or the bright portion 222 and the dark portion 221 of the edge region. The reason is that the relatively bright part of the edge area is corrected brighter, and the relatively dark part is corrected darker.

Hereinafter, a method of examining whether an edge region and what type of edge region is applied by applying a mask according to the present invention will be described.

First, in order to detect the edge region, the present invention multiplies the gray scale data of the image corresponding to the multiplication coefficient value of the mask (S120).

That is, M (i-1, j-1) and P (i-1, j-1) multiply M (i-1, j) and P (i-1, j) by multiplying M (i Multiply by + 1, j + 1).

Next, SUM is obtained by adding all the multiplied values as described above (S130). That is, SUM can be obtained by Equation 1 below.

The multiplication coefficient value of the mask is M (i, j), which is a multiplication coefficient value corresponding to the center pixel, to have a positive real value, and the multiplication coefficient value of the mask corresponding to the remaining pixels is negative. By properly adjusting the multiplication coefficient value, the sum value of the sum may be close to 0 when even the pixel system is small and the positive or negative big value when the system is large.

The Sum value is compared with a predetermined threshold to determine whether it is an edge region (S140, S150). If the Sum value is less than the -reference value (the reference value × -1) or is greater than the + reference value (positive value), the edge region is determined. If the value is between-reference value and + reference value, it is regarded as not edge area. Wherein the reference value is a positive value.

In addition, if the Sum value is less negative than the -reference value, it is determined as an edge region of a relatively dark portion of the edge region.

On the contrary, if the Sum value is a positive number greater than the + reference value, it is determined as an edge region of a relatively bright portion of the edge region.

Therefore, the sensitivity of the edge region is determined by how close the reference value is to 0. A detailed example will be described below.

8A is a diagram illustrating an embodiment of a mask to which the plasma display device driving method according to the present invention is applied, and FIGS. 8B and 8C illustrate an example of grayscale data of an image to which the plasma display device driving method according to the present invention is applied. Figure shown.

In the present invention, as shown in FIG. 8A, a 3 × 3 Laplacian mask is used as an example of the mask, which has a multiplication coefficient M (i, j) of +8 corresponding to a center pixel, and a multiplication coefficient of the remaining neighboring pixels. The value is a mask set to -1.

The edge area detection will be described using the grayscale data of FIGS. 8B and 8C as an example. The gray scale used in the present embodiment will be described based on a total of 256 gray scales having a gray scale level of 0 to 255, but is not limited thereto.

As described above, the edge region includes relatively bright and dark portions based on the boundary line. 8B is a portion where the gray scale value of the center pixel is 100, and is a relatively dark portion as the edge region near the boundary line. A portion having a gray value of 200 among the surrounding pixels is a relatively bright portion of the edge region. The larger the gradation value, the brighter it is and the smaller the gradation it is. Applying the mask to determine it mathematically as follows.

When the mask of FIG. 8A is applied to the gray scale data of FIG. 8B and the sum is obtained according to Equation 1, sum = − (100 × 5 + 200 × 3) + 8 × 100 = -1100 + 800 = -300. In this case, if the reference value is set to 100, since the center pixel is a negative value less than -100, which is a -reference value, the center pixel is an edge region, and more specifically, it is determined as an edge region of a relatively dark portion.

8C is a portion where the gray value of the center pixel is 200, which is lighter than 100 in the edge region near the boundary line. The portion having the gradation value 100 of the surrounding pixels is a relatively dark portion of the edge region. Applying the mask to determine it mathematically as follows.

When the mask of FIG. 8A is applied to the gray scale data of FIG. 5C and the sum is obtained according to Equation 1, sum = − (200 × 5 + 100 × 3) + 8 × 200 = -1300 + 1600 = 300. In this case, if the reference value is set to 100, since the center pixel is a positive value larger than +100, which is a + reference value, it is determined as an edge area and more specifically, an edge area of a relatively bright portion.

If the reference value is properly adjusted using the Laplacian mask as described above, the edge region can be determined with the desired sensitivity.

In the present invention, the edge area is detected as described above, and the gray area is corrected so that the bright part is lighter and the dark part is darker by determining whether the edge area is the edge area of the relatively bright part or the relatively dark part of the edge area (S141). ).

That is, in the case of the edge region of the relatively dark part, the output gray scale value is corrected to a value obtained by reducing the input gray scale value (the original gray scale value of the pixel) by a predetermined compensation value (output gray value = input gray scale value -compensated value). do. On the contrary, in the edge region of the relatively bright portion, the output gray scale value is corrected to be a value obtained by increasing the input gray scale value by a predetermined compensation value (output gray value = input gray scale value + compensation value) (S151).

As described above, the difference between the output grayscale value and the input grayscale value used for correction is called a compensation value, and it can be corrected by the same difference as the edge region of the dark portion or the edge region of the bright portion by setting it as a predetermined fixed value. The compensation value can be corrected differently according to the input gradation value according to the brightness of the input gradation value. That is, the correction value is corrected by having various values different according to the input gray scale values without fixing the compensation value.

That is, for example, in a pixel of an edge area having an input gradation value of 100 and an input gradation value of 200, an edge region having a gradation value of 200 if gradation correction is performed with a compensation value of about 2 at a gradation value of 100 during gradation correction In the pixels of, the tone can be corrected to a more dynamic and natural image quality by adjusting the gradation with a compensation value of about 5 degrees. The reason is that human's visual sensitivity is more sensitive in the dark part, so if you adjust the gray level value near 100 to the final gray level value of 95 and convert it to the final gray level value of 95, the difference in the brightness of the outline in the dark area becomes too large. Because it can be and may not be natural.

At this time, the compensation value may be differently designated for each gray level, but it is more preferable to change the compensation value for each group by grouping each predetermined gray level.

In the present invention, one of the methods for causing the compensation value to have a value that varies fluidly according to the gradation of the original pixel will be described.

Dividing the entire gray level into at least two gray level groups and assigning different compensation values to each gray level group.

In detail, based on 256 gradations, the total gradations are divided into two or more gradation groups in gradation order from 0 to 255 gradations. For example, by dividing the gradation group in the order of gradation 0 ~ 45, gradation 46 ~ 80, gradation 81 ~ 110, and so on, the 0 It may be assigned to have a compensation value, and may be assigned to increase the compensation value as the group gradually increases its average gradation level.

The interval and size of the compensation value for each gradation group can be appropriately adjusted to such an extent that the distortion of the image quality is not large.

9 is a graph showing a compensation value according to an input gradation level in the plasma display device driving method according to the present invention, and Table 1 below is a table of the compensation values according to the gradation value. 9 and Table 1 show compensation values in the same manner as described above.

Gradation level Compensation value 0 to 45 0 46-80 One 81-110 2 111-140 3 141-170 4 171 ~ 200 5 201-255 6

The compensation value is not limited to Table 1, but may be set in various ways.

If it is determined that it is not an edge area, the output gradation value and the input gradation value are the same. In other words, the grayscale value is kept the same without correction (S160).

10A is a diagram illustrating an original image to which the plasma display device driving method according to the present invention is not applied, and FIG. 10B is a diagram illustrating an image to which gray level compensation is applied by applying the plasma display device driving method according to the present invention.

When the plasma display device driving method according to the present invention is applied to an image in which dark parts and bright parts alternately as shown in FIG. 10A, the inner and outer contrasts are more emphasized based on the boundary as shown in FIG. 10B.

That is, since the edge region of the outer portion is expressed a little darker with respect to the boundary line, and the inner edge region of the boundary line is expressed a little brighter, an image having a clearer boundary can be seen.

As described above, the method for driving the plasma display device according to the present invention has been described with reference to the illustrated drawings. However, the present invention is not limited by the embodiments and drawings disclosed herein, and may be applied within the scope of the technical idea. have.

Plasma display device driving method according to the present invention configured as described above has the effect of correcting the contour and the edge area of the object to clear the boundary between the object and the background and output a clear image, it is possible to output a more three-dimensional image. In addition, it has the effect of improving image quality and reducing visual fatigue by improving recognition and discrimination of background and objects.

Claims (14)

A first step of converting RGB image data into gradation data; A second step of multiplying the gradation data and the multiplication coefficient value using a mask having a multiplication coefficient value and detecting an edge region based on the multiplied values and a predetermined reference value; And a third step of correcting the pixel gray scale of the edge region by changing a compensation value according to the relative brightness of the edge region. The method according to claim 1, The second step may include a multiplication process of multiplying the grayscale data of the center pixel and its neighboring pixels to be processed by the multiplication coefficient value of the mask; A summing process of summing all the values multiplied in the multiplication process and calculating a result value; And an edge discrimination process of comparing the resultant value with the predetermined reference value to determine whether the center pixel belongs to an edge region. The method according to claim 2, And wherein said mask has a positive value of a multiplication coefficient of said mask corresponding to said center pixel. The method according to claim 3, And said multiplication factor value is eight. The method according to claim 2, And wherein the mask has a negative value of a multiplication coefficient of the mask corresponding to the peripheral pixel. The method according to claim 5, And said multiplication coefficient value is -1. The method according to claim 2, And the mask has a size of three rows and three columns. The method according to claim 2, The edge discrimination process determines the first edge area when the result value is equal to or less than -the reference value, and determines the second edge area when the result value is equal to or greater than the + reference value, and the result value is the And-if the value is between the reference value and the + reference value, discriminating that it is not an edge region. The method of claim 8, In the third step, the gray scale of the center pixel is reduced by the compensation value when the center pixel corresponds to the first edge region. The method of claim 8, And wherein the third step is to increase the gray level of the center pixel by the compensation value when the center pixel corresponds to the second edge region. The method according to any one of claims 9 or 10, And the compensation value is set differently according to the basic gray level of the center pixel. The method according to claim 11, And the compensation value is set differently for each gradation group by dividing the entire gradation into at least two gradation groups according to the gradation order. The method according to claim 12, And the compensation value gradually increases from the gradation group having the lowest average gradation level among the gradation groups to the gradation group having the highest average gradation level. The method of claim 13, And the compensation value of the gradation group having the lowest average gradation level is set to 0, and the compensation value is increased by 1 as the gradation group has a higher average gradation level.

Images