KR20000059943A - Method for removing of false contour on PDP - Google Patents

Abstract

PURPOSE: A method for removing a pseudo outline of a plasma display panel is provided to enhance an image quality by removing a pseudo outline of an image displayed on a flat panel display panel such as PDP simultaneously with using a grey level data of 8-bit. CONSTITUTION: A plasma display panel drives one pixel of a first field of a first vertical pulse period and one pixel of a second field of a second vertical pulse period. The plasma display panel drives(first step) a pixel by setting a weight value of a sub-field in order to display a contact grey level on one pixel of the first field. The plasma display panel drives a pixel(second step) in order to display the same grey level as the above step, in opposition to the set sub-field weight value. The plasma display panel drives(third step) a pixel with the same weight value as the first step, in order to display a changed grey level of one pixel of the second field. The plasma display panel drives a pixel in order to display the same grey level as the third step, by using the same weight value of the second step. The plasma display panel displays one grey level by using the first and second steps, and displays a changed grey level by using the third and fourth steps, and makes a border's grey level to have average grey level between two grey levels. Thereby, an image quality is enhanced by removing a pseudo outline of an image.

Description

Method for removing contour of plasma display panel {Method for removing of false contour on PDP}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel (hereinafter referred to as a PDP), and more particularly, to a method of removing an outline of a plasma display panel such that a pseudo outline does not appear in an image displayed on a flat panel display device such as a PDP. It is about.

PDP puts Ne + Ar, Ne + Xe, etc. gas between the front glass and the back glass and the glass enclosed by the partition therebetween, and applies a voltage through the anode and cathode electrodes to emit neon light to display light. The electronic display device to be used is called. PDP is an emission type display that can display large images with clear image. Therefore, it has been used for factory automation (FA), ticket vending machine, gas flow meter, etc., and the large panel displays high quality and quick response time. High reliability

In general, when the PDP displays 256 gray levels, the PDP drives the corresponding pixels according to the gray level data. 8-bit gradation data for representing 256 gradations is divided into a plurality of subfields, and each subfield is given a different weight for gradation expression.

1 is a structural diagram of a subfield and a television field of a plasma display panel. In the plasma display panel, when the luminance of an image displayed on the screen is represented by 256 gray levels, one television field is divided into eight subfields. Here, one television field is 8-bit data used to express the gray level of one pixel. Each subfield is composed of a reset period, an address period, and a sustain period. Of these, the duration is substantially used to display the picture on the PDP. In the duration, each pixel constituting the screen is gas discharged. However, for ease of explanation, the following description will be made with 4 bits of gray scale data that can represent 0 to 15 gray scales.

FIG. 2 is a diagram illustrating an on / off state of a duration of each subfield when a gray level is changed. 2 shows weights of subfields 1t, 2t, 4t, and 8t (where t is a unit time) to represent 0 to 15 grayscales, respectively, from low to high bits of 4-bit grayscale data, respectively. The pixels are driven with weights of 1t, 2t, 4t, and 8t. In this case, one television field is composed of four subfields. For example, when the gradation is changed from 7 to 8 in any pixel, the pixel is driven for 1t to 4t period and the pixel is not driven for only 8t period to display 7 gradations. Then, when the eight gradations are displayed, the pixels are not driven for the 1t to 4t period, but the pixels are driven for the 8t period to display the eight gradations. Here, driving the pixel means to turn on the corresponding electrode to excite the neon gas, and not to drive the pixel means to turn off the corresponding electrode in the reverse case. As shown in FIG. 3, the "off" section is lengthened at the boundary that changes from the 7th to 8th gradations. As shown in FIG. FIG. 4 is a diagram for explaining pseudo contours, in which the horizontal axis shows an arrangement of subfields that two television fields can have, and the vertical axis shows the gradation values that the first television field can have. Similarly in FIG. 4, it can be seen that black pseudo contours of zero gray scales appear when gray pixels are changed from seven gray scales to eight gray scales in two television fields in an arbitrary pixel.

Many methods for reducing pseudo contours, which are problems of PDP, have been introduced. Among them, when using 8-bit grayscale data, a method of dividing the upper 2 bits into four subfields is often used. In 8-bit gradation data of 1t, 2t, 4t, 8t, 16t, 32t, 64t, and 128t, the weights of subfields remove weights of 1t and 2t which have little effect on gradation display and greatly affect gradation display. The 64t and 128t are driven by four 48t with the weight of the subfield. Therefore, the weight of the subfield is represented by 6-bit gradation data of 4t, 8t, 16t, 32t, 48t, 48t, 48t, and 48t.

However, even in the above method, it is difficult to completely remove the pseudo contour, and there is a problem in that the image quality is degraded because the 6-bit grayscale data is displayed.

Accordingly, an object of the present invention is to provide a pseudo contour removal method of a plasma display panel which removes pseudo contours while using 8-bit gray scale data as it is so as to solve the above problems.

1 is a structural diagram of a subfield and a television field of a plasma display panel;

2 is a diagram illustrating an on / off state of a duration of each subfield when a grayscale change is performed in the related art;

FIG. 3 is a diagram illustrating a pseudo contour in gray level change according to an on / off state of a duration of FIG. 2; FIG.

4 is a view for explaining pseudo contours,

5 is a view showing the on / off state of the duration during the gradation change according to the present invention,

6 is a view showing an application sequence of the duration of FIG. 5 during a vertical pulse period according to the present invention;

7 is a view showing a state in which the pseudo contour is removed by the pseudo contour removal method of the present invention.

In order to achieve the above object, the method of removing the pseudo contour of the plasma display panel according to the present invention includes the first step of driving the pixel by setting the weight of the subfield so as to display a constant gray level in one pixel of the first field; A second step of driving the pixel to have the same gray level as in the first step as opposed to the subfield weight set in the first step; and a pixel with the same weight as the first step to indicate the changed gray level in one pixel of the second field. A third step of driving, and a fourth step of driving the pixel to display the same gray level as the third step with the same weight as the second step, wherein the first step and the second step represent one gray level, The gradation is changed to the fourth and fourth stages, and the gradation at the boundary at which the gradation changes is characterized by having an average gradation of the two gradations.

In the present invention, gray scale data of 8 bits is used to represent gray scales for an arbitrary pixel. In this case, 16 subfields are configured. The weights of the 16 subfields are 1t, 2t, 4t, 8t, 16t, 32t, 64t, 128t, 128t, 64t, 32t, 16t, 8t, 4t, 2t, 1t. In the case of seven gradations, the pixel is driven for the periods 1t to 4t and 4t to 1t. If one volt is applied to 1t of FIG. 2 to drive the pixel, 0.5 volts are applied to the two 1t. By expressing the gray scale in this way, it is possible to eliminate pseudo contours generated when the gray scale changes. This will be described in more detail with reference to the accompanying drawings, a preferred embodiment of the present invention.

For convenience of explanation, the following describes an embodiment in which the gray level of an arbitrary pixel is represented by 4-bit grayscale data that can represent 0 to 15 gray scales.

5 is a view showing the on / off state of the duration in the grayscale change according to the present invention. FIG. 5A shows seven gradations and eight gradations with weights in the same manner as in FIG. The weight of the subfield of FIG. 5B is set opposite to that of FIG. 5A. That is, the weight of each subfield is set to 8t, 4t, 2t, and 1t to represent 0 to 15 gradations, and the weights of 8t, 4t, 2t, and 1t, respectively, from the low bit to the high bit of the 4-bit gradation data. Drive the pixel. For example, when the gradation is changed from 7 to 8 in any pixel, the pixel is not driven only during the 8t period, and the pixel is driven during the 4t to 1t period to display 7 gradations. Then, when the eight gradations are displayed, the pixels are driven only during the 8t period, and the pixels are not driven during the 4t to 1t periods, thereby showing the eight gradations. Then, 15 grays occur between 7 grays and 8 grays. That is, when the weights of the subfields are 8t, 4t, 2t, and 1t, the white pseudo contour between 7 to 8 gradations is due to the "on" state of the 4t to 8t sections of FIG. 5B. Reference will be apparent to those skilled in the art.

In order to remove pseudo contours when gray level changes in any one pixel by using the weight of the subfield configured as described above, first, in order to display seven gray levels, one pixel during the first vertical pulse period is shown in FIG. 1t, 2t, 4t, and 8t from SF1 to SF4 and 8t, 4t, 2t, and 1t from SF1 to SF4 in FIG. 5B. Here, since 1t, 2t, and 4t are turned on two by one to represent seven gray levels during one vertical pulse period, the voltage for emitting the display light is divided into two subfields having the same weight. That is, if 1 volt is applied to 1t of FIG. 2, the same gray level can be obtained by adding 0.5 volts to each of the two 1t of FIG. 5. Next, 1t, 2t, 4t and 8t from SF5 to SF8 in FIG. 5A and 8t, 4t, 2t and 1t from SF5 to SF8 in FIG. 5B are shown in one pixel during the second vertical pulse period to express 8 gray scales. Indicates. That is, each gradation is shown in the order of ① → ② → ③ → ④, and the average gradation of the two gradations appears in the human eye. Then, 0 gray and 15 gray do not appear in the gray level at one pixel of one PDP screen composed of fields during two vertical pulse periods. That is, even if the gray level of one pixel is changed from 7 to 8, the black pseudo outline of 0 gray and the white pseudo outline of 15 gray are averaged, so that the gray level visually displayed in the human eye becomes 7.5. When several pixels become one vertical line, black or white pseudo contours do not occur as shown in FIG.

As described above, the method of the present invention has the effect of removing pseudo contours when the gray scale of the PDP changes, thereby bringing an improvement in image quality.

Claims (1)

A plasma display panel which drives any one pixel of a first field during a first vertical pulse period and a second field during a second vertical pulse period having a plurality of subfields, Driving a pixel by setting a weight of a subfield so as to display a constant gray level in one pixel of the first field; A second step of driving the pixel so as to have the same gray level as the first step as opposed to the subfield weight set in the first step; A third step of driving the pixel with the same weight as that of the first step to represent the changed gray level in one pixel of the second field; And A fourth step of driving the pixel to have the same gray level as the third step with the same weight as the second step, The first contour and the second phase represent one gray level, the gray level changed to the third level and the fourth level, and the gray level at the boundary at which the gray level changes has an average gray level of two gray levels. Way.