KR100547980B1 - Method and Apparatus For Driving Plasma Display Panel - Google Patents

Abstract

The present invention relates to a method and apparatus for driving a plasma display panel to minimize contour noise at low grayscale and to minimize flicker at medium / high grayscale.

A plasma display panel driving method and apparatus includes: a first subfield group having a low weight subfield, a medium weight subfield pattern, and a high weight subfield pattern; A second subfield group having the middle weight subfield pattern and the high weight subfield pattern without the low weight subfield is disposed within one frame period.

Description

Method and apparatus for driving plasma display panel {Method and Apparatus For Driving Plasma Display Panel}             

1 is a perspective view showing a discharge cell of a conventional three-electrode AC surface discharge type plasma display panel.

2 is a diagram illustrating a subfield pattern including eight subfields time-divided in one frame period.

3 is a diagram illustrating a subfield pattern for explaining a conventional method of driving 50 Hz.

4 is a diagram illustrating a subfield pattern for explaining another conventional method of driving 50 Hz.

FIG. 5 is a diagram illustrating an example of a subfield pattern shown in FIG. 4.

FIG. 6 is a diagram illustrating gradation representations using the subfield pattern of FIG. 5.

7 illustrates a subfield pattern according to an embodiment of the present invention.

FIG. 8 is a diagram illustrating an example of a subfield pattern shown in FIG. 7.

FIG. 9 is a diagram illustrating gradation representations using the subfield pattern of FIG. 8.

10 is a block diagram illustrating an apparatus for driving a plasma display panel according to an exemplary embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

10: upper substrate 11: metal bus electrode

12 transparent electrode 13, 17 dielectric layer

14: shield 15: bulkhead

16: phosphor 18: lower substrate

101: image quality processing unit 102: frequency detection unit

103: subfield mapping unit

The present invention relates to a method and apparatus for driving a plasma display panel, and more particularly, to a method and apparatus for driving a plasma display panel to minimize contour noise at low gradations and to minimize flicker at medium and high gradations. It is about.

The plasma display panel (hereinafter referred to as "PDP") displays an image by emitting phosphors by ultraviolet rays generated when the He + Xe or Ne + Xe inert mixed gas is discharged. Such PDPs are not only thin and large in size, but also greatly improved in image quality due to recent technological developments. In particular, the three-electrode AC surface discharge type PDP has advantages of low voltage driving and long life because wall charges are accumulated on the surface during discharge and protect the electrodes from sputtering caused by the discharge.

Referring to FIG. 1, a three-electrode AC surface discharge type PDP includes a plurality of scan electrodes Y and a plurality of sustain electrodes Z formed on an upper substrate 10, and an address electrode formed on a lower substrate 18. (X) is provided.

The discharge cells of the PDP are formed at the intersections of the scan electrodes Y, the sustain electrodes Z, and the address electrodes X, and are arranged in a matrix.

Each of the scan electrode Y and the sustain electrode Z includes a transparent electrode 12 and a metal bus electrode 11 having a line width smaller than that of the transparent electrode 12 and formed at one edge of the transparent electrode. The transparent electrode 12 is typically formed on the upper substrate 10 by indium tin oxide (ITO). The metal bus electrode 11 is formed of a metal on the transparent electrode 12 to reduce the voltage drop caused by the transparent electrode 12 having a high resistance. The upper dielectric layer 13 and the passivation layer 14 are stacked on the upper substrate 10 on which the scan electrodes Y and the sustain electrodes Z are formed. Wall charges generated during plasma discharge are accumulated on the upper dielectric layer 13. The passivation layer 14 protects the electrodes Y and Z and the upper dielectric layer 13 from sputtering generated during plasma discharge and increases the emission efficiency of secondary electrons. As the protective film 14, magnesium oxide (MgO) is usually used.

The address electrodes X are formed on the lower substrate 18 in a direction crossing the scan electrodes Y1 to Yn and the sustain electrode Z. The lower dielectric layer 17 and the partition wall 15 are formed on the lower substrate 18. The phosphor layer 16 is formed on the surfaces of the lower dielectric layer 17 and the partition wall 15. The partition wall 15 physically separates the discharge cells. The phosphor layer 16 is excited and emitted by ultraviolet rays generated during plasma discharge to generate visible light of any one of red, green, and blue.

An inert mixed gas such as He + Xe, Ne + Xe, He + Xe + Ne for discharging is injected into the discharge space of the discharge cells provided between the upper / lower substrates 10 and 18 and the partition wall 15.

The three-electrode AC surface discharge type PDP is driven by dividing one frame into several subfields having different emission counts in order to realize gray levels of an image. When the image is to be displayed in 256 gray levels, the frame period (16.67 ms) corresponding to 1/60 second is divided into eight subfields SF1 to SF8 as shown in FIG. Each subfield SF1 to SF8 is divided into a reset period for initializing discharge cells, an address period for selecting discharge cells, and a sustain period for implementing gray levels according to the number of discharges. The reset period and the address period of each subfield SF1 to SF8 are the same for each subfield, while the sustain period and the number of discharges thereof are 2 ⁿ in each subfield (where n = 0,1,2,3,4). , 5,6,7).

In the PDP, when the observer subjectively perceives an image according to a light emission pattern according to a subfield combination, contour noise tends to appear in a moving image, and flicker tends to appear when the emission center is shaken every screen.

As a method for removing the contour noise, a method of adding subfields by dividing a subfield, a method of rearranging the order of subfields, a method of adding a subfield, rearranging the order of subfields, an error diffusion method, and the like This is known.

As a method for reducing flicker, a method of matching the emission center with each frame, increasing the frequency, and the like have been proposed by calculating the timing at which the emission center appears. The former method has a light center as disclosed in Korean Patent Laid-Open Publication No. 10-2000-0070527 when the light center of maximum brightness fluctuates from frame to frame in a subfield pattern in which luminance weights are linearly arranged as shown in FIG. Is a method of reducing flicker by matching every frame. However, this method has a disadvantage in that complicated algorithms and circuits are added for calculation to match the optical center. In FIG. 3, 'Vsync' is a vertical synchronization signal, and 'SFP' is a subfield pattern including a plurality of subfields. The latter method can display an image signal of 50 Hz as disclosed in Korean Unexamined Patent Publication Nos. 10-2000-0016955, 10-2002-0069237, 10-2003-0021483, 10-2003-0039282, and the like. When one frame period (20 ms), two sub-field patterns are overlapped as shown in FIG. 4 to increase the frequency to a similar 100 Hz to reduce flicker. The subfield pattern as shown in FIG. 4 generally includes two subfield groups SFG1 and SFG2 in which subfields are arranged in order of increasing weight.

Tables 1 and 5 show an example when the subfield pattern SFP shown in FIG. 4 includes 13 subfields, and FIG. 6 shows each gray level representation using the subfield pattern SFP shown in Table 1 below. . In FIG. 6, '1' means a subfield in which display discharge occurs in the discharge cell, and '0' means a subfield in which display discharge does not occur in the discharge cell.

Subfield SF1 SF2 SF3 SF4 SF5 SF6 SF7 SF8 SF9 SF10 SF11 SF12 SF13 weight One 2 5 10 21 33 46 3 7 15 25 37 50

However, as shown in FIG. 4, when two subfield patterns are overlapped in one frame period, contour noise may appear twice in one frame period in each subfield pattern, and the number of gray scales that can be expressed compared to the number of subfields is small. In particular, since the subfield pattern shown in FIG. 4 has many on / off subfields in adjacent gray scales in all gray scales, outline noise tends to occur in a moving image.

Accordingly, an object of the present invention is to provide a method and apparatus for driving a plasma display panel to minimize contour noise at low grayscale and to minimize flicker at medium / high grayscale.

In order to achieve the above objects, a driving method of a PDP according to the present invention comprises: a first subfield group having a low weight subfield, a medium weight subfield pattern, and a high weight subfield pattern; And a second subfield group having the middle weight subfield pattern and the high weight subfield pattern without the low weight subfield.

The first and second subfield groups are arranged within one frame period.

When the maximum luminance of the PDP is 100%, a weight of about 2.745% or less is assigned to the low-weight subfield, and a weight of about 3.137% to about 31.373% of the intermediate weight subfield is given. The high weight subfield is weighted between approximately 31.764% and 100%.

The one frame period is between 16 ms and 20 ms.

Subfields are arranged in each of the first subfield group and the second subfield group in order of high weight subfields to low weight subfields.

A driving apparatus of a PDP according to the present invention includes a first subfield group having a low-weight subfield, a medium-weight subfield pattern, and a high-weight subfield pattern, and a subfield of the intermediate weight without the low-weight subfield. A memory storing a subfield pattern including a pattern and a second subfield group having the high weight subfield pattern; And a subfield mapping unit configured to map video data to the subfield pattern in response to at least one of a driving frequency and an external command.

Other objects and features of the present invention in addition to the above object will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 7 to 10.

Referring to FIG. 7, in the method of driving a PDP according to an embodiment of the present invention, two subfields are arranged in order of gradually decreasing weight when the frequency of an image signal is 50 Hz, such as PAL (Phase Alternation by Line). The subfield groups ISFG1 and ISFG2 are distributed within one frame period (20 ms).

The first subfield group ISFG1 is arranged at the head of one frame period, for example, 20 ms frame period in the PAL method. The first subfield group ISFG1 has high weighted subfields for expressing high gradation and is placed in front of the middle weighted subfields for expressing middle gradation and low weight value for expressing low gradation. Subfields are placed after it. Therefore, in the first subfield group ISFG1, subfields are arranged in the order of high weight to low weight.

=2.745% 이하의 가중치가 부여되는 서브필드들로 정의되고, 중간 가중치의 서브필드들은

=3.137% 에서

=31.373% 사이의 가중치가 부여되는 서브필드들로 정의된다. 그리고 고가중치의 서브필드들은

=31.764% 에서

=100% 사이의 가중치가 부여된다. On the other hand, assuming that the maximum luminance when the PDP is turned on full white is 100%, the low-weight subfields

Are defined as subfields that are weighted less than or equal to 2.745%.

At = 3.137%

It is defined as subfields that are weighted between 31.373%. And high-weight subfields

At = 31.764%

Weighted between = 100%.

The second subfield group ISFG2 is disposed after the first subfield group ISFG1. In this second subfield group ISFG2, high-weight subfields for expressing high gradation are disposed in front, and intermediate weighted subfields for expressing intermediate gradation are disposed behind. Accordingly, in the second subfield group ISFG2, subfields are arranged in the order of high weight to medium weight without the low-weight subfield pattern.

Table 2 and FIG. 8 show an example when the subfield pattern shown in FIG. 7 includes 13 subfields, and FIG. 9 shows on / off of the subfields when expressing each gray level using the subfield pattern shown in Table 2. Indicates. In FIG. 9, '1' means a subfield in which display discharge occurs in the discharge cell, and '0' means a subfield in which display discharge does not occur in the discharge cell.

Subfield SF1 SF2 SF3 SF4 SF5 SF6 SF7 SF8 SF9 SF10 SF11 SF12 SF13 weight 47 37 22 10 7 4 2 One 45 33 21 15 11

In the subfield pattern of Table 2 and FIG. 8, the first subfield group ISFG1 includes a subfield of weight '47', a subfield of weight '37', a subfield of weight '22', and a subfield of weight '10'. , Subfields of weight '7', subfields of weight '4', subfields of weight '2' and weights '1'.

In the subfield pattern of FIG. 2 and FIG. 8, the second subfield group ISFG2 includes a subfield of weight '45', a subfield of weight '33', a subfield of weight '21', and a subfield of weight '15'. And the subfields are arranged in order of the subfield of the weight '11'. Accordingly, the second subfield group ISFG2 has no low-weight subfields having a weight less than or equal to 10 and medium weight subfields having a weight between 10 and 20 and high weights having a weight greater than or equal to 21. It contains subfields of.

The subfield patterns of Tables 2 and 8 express low gray levels using low-weight subfields in the first subfield group ISFG1 arranged before and after an intermediate point in one frame period as shown in FIG. The mid / high gradation is expressed by using the mid / high weight subfields in the first subfield group ISFG1 and the mid / high weight subfields in the second subfield group ISFG2 distributed in the first and second parts. .

According to the subfield patterns of Table 2 and FIG. 8, in the low gray scale expression, the discharge cells are continuously turned on in the adjacent low-weight subfields. On the other hand, flicker is not noticeably noticeable at low gradation.

When the medium / high gradation is expressed by the subfield patterns shown in Table 2 and FIG. 8, the discharge cells are divided into the medium / high weighted subfields distributed in the first subfield group ISFG1 and the second subfield group ISFG2. Lights up.

Therefore, the driving method of the PDP according to the present invention minimizes pseudo contour noise because the flicker is small and the subfields are continuously turned on when the low gray level is expressed in the video, and the distribution of light is balanced in the medium / high gray level. Flicker is minimized since the light emitting center is almost unshakable.

10 shows an apparatus for driving a PDP according to an embodiment of the present invention.

Referring to FIG. 10, an apparatus for driving a PDP according to the present invention uses the image quality processing unit 101 and the frequency detector 102 to which digital video data RGB is input, and the data from the image quality processing unit 101 as shown in FIG. A subfield mapping unit 103 for mapping to a subfield pattern is provided.

The image quality processor 101 receives the digital video data RGB, the vertical / horizontal sync signal, and the clock signal CLK, and performs inverse gamma correction, gain correction, error diffusion, and dither processing on the digital video data RGB. The subfield mapping unit 103 is supplied.

The frequency detector 102 detects the driving frequency of the video signal currently input by using the digital video data RGB and the frequency, period, and pulse width of the vertical / horizontal synchronization signal H / V. The frequency detector 102 supplies the subfield mapping unit 103 with a frequency discrimination signal indicating a driving frequency of the video signal currently input.

The subfield mapping unit 103 stores a subfield pattern as shown in FIGS. 7, Tables 2 and 8, a subfield pattern optimally set at a 60 Hz driving frequency, and the like, and a desired subfield by accessing the memory. And a subfield mapper (not shown) for mapping the digital video data from the image quality processing section 101 to the field pattern.

The subfield mapping unit 103 displays digital video data from the image quality processing unit 101 under the control of an external mode conversion signal by indicating that the frequency discrimination signal from the frequency detection unit 102 indicates 50 Hz. It is supplied to the PDP by mapping to a subfield pattern such as

The external mode conversion signal can be input by the manufacturer's operator or user. The external mode conversion signal is input or changed through an interface such as an on screen display (OSD) or a remote controller.

In addition, the subfield mapping unit 103 is a subfield in which the frequency discriminating signal from the frequency detecting unit 102 indicates 60 Hz or the digital video data from the image quality processing unit 101 is optimally set at 60 Hz under the control of an external mode conversion signal. Map to the pattern and feed it to the PDP.

On the other hand, the subfield pattern of Table 2 is not limited to the case where the frequency of the video signal is 50 Hz, but also applied to the case where the frequency of the video signal is 60 Hz, as in the NTSC television system, thereby reducing flicker and contour noise. In this case, regardless of the frequency of the image input to the image quality processor 101 in FIG. 10, the subfield mapping unit 103 maps the image data to the subfield patterns of Table 2.

As described above, the method and apparatus for driving a PDP according to the present invention can minimize contour noise by continuously turning on discharge cells in adjacent subfields during low gray scale expression with little flickering, and medium / high gray scale. The light emission center can be dispersed to minimize flicker.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (8)

Low-weight subfields for low gradation, medium-weighted subfield patterns for mid-gradation, and high-weight subfield patterns for high gradation. A first subfield group in which subfields are arranged; A second subfield group having the subfield pattern of the intermediate weight and the high weight subfield pattern without the low weight value subfields, wherein the subfields are arranged in the order of the high weight subfields and the low weight subfields. Includes; And the first and second subfield groups are arranged within one frame period. The method of claim 1, When the maximum luminance of the plasma display panel is 100%, the low-weight subfield is given a weight of approximately 2.745% or less; The intermediate weighted subfield is weighted between approximately 3.137% and approximately 31.373%; And said weighted subfield is weighted between approximately 31.764% and 100%. The method of claim 1, And the frame period is between 16 ms and 20 ms. delete Low-weight subfield for low gradation, medium weight subfield pattern for mid-gradation, and high weight subfield pattern for high gradation. A first subfield group in which the subfields are arranged, the subfield pattern having the intermediate weight and the high weight subfield pattern without the low weight subfield, and having the highest weight subfields in order A memory in which a subfield pattern including a second subfield group in which subfields are arranged is stored; And a subfield mapping unit configured to map video data to the subfield pattern in response to at least one of a driving frequency and an external command. The method of claim 5, When the maximum luminance of the plasma display panel is 100%, the low-weight subfield is given a weight of approximately 2.745% or less; The intermediate weighted subfield is weighted between approximately 3.137% and approximately 31.373%; And said high weight subfield is weighted between approximately 31.764% and 100%. The method of claim 5, And the frame period is between 16 ms and 20 ms. delete

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