KR100444510B1 - Apparatus And Method For Driving Plasma Display Panel Using An Enlarging Method Of Dynamic Range - Google Patents

Abstract

The present invention relates to an apparatus and method for driving a plasma display panel using a dynamic range magnification method to improve contrast of a display screen through expansion of a dynamic range when displaying a moving image.

The driving device of the plasma display panel using the dynamic range expansion method according to the present invention is a frame memory for storing moving picture data from an external input line in units of frames, and is connected between the frame memory and the panel and has a minimum distribution of lower and upper gray levels. A dynamic range converting unit for converting the dynamic range of the moving image data according to the information, and a parallel connection between the input line and the dynamic range converting unit in parallel with the frame memory, according to the video data type from the input line; A minimum low and high gray level restriction serially connected to a minimum low and high gray level limiting unit and a minimum low and high gray level limiting unit for limiting the gray level, and the minimum low and high gray level for one frame according to the gray level limiting information. Linearly converts the luminance value according to the gray level value of the video signal by performing reverse gamma correction on the video data of which the dynamic range is converted by serial connection between the lower and upper gray level detectors for detecting a signal and the dynamic range converter and the panel. It characterized in that it comprises a reverse gamma correction unit.

Description

Apparatus And Method For Driving Plasma Display Panel Using An Enlarging Method Of Dynamic Range}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel, and more particularly, to an apparatus and method for driving a plasma display panel using a dynamic range enlargement method for improving contrast of a display screen through expansion of a dynamic range during moving image display.

Plasma Display Panel (hereinafter referred to as "PDP") is a display device using visible light generated from a phosphor when ultraviolet light generated by gas discharge excites the phosphor. PDP is thinner and lighter than Cathode Ray Tube (CRT), which has been the mainstay of display means, and has the advantage of realizing high definition / large screen.

The PDP has an upper substrate and a lower substrate which are installed to face each other with partition walls therebetween. The upper substrate includes a scan electrode and a sustain electrode formed in a direction crossing the partition wall. The lower substrate includes an address electrode formed in a direction parallel to the partition wall, and a dielectric layer formed to cover the address electrode. The discharge cell is positioned at the intersection of the scan electrode, the sustain electrode and the address electrode.

The PDP is driven by dividing one frame into several subfields having different emission counts in order to realize gray levels of an image. Each subfield is divided into a reset period for uniformly causing discharge, an address period for selecting a discharge cell, and a sustain period for implementing gray scale according to the number of discharges.

In the address period, scan pulses are supplied to the scan electrodes, and data pulses synchronized with the scan pulses are supplied to the address electrodes. At this time, an address discharge occurs in the discharge cell supplied with the scan pulse and the data pulse. After the scan pulses are supplied to all the scan electrodes, the sustain pulses are alternately supplied to the scan electrodes and the sustain electrodes. When a sustain pulse is supplied to the scan electrode and the sustain electrode, sustain discharge occurs in the discharge cells in which the address discharge has occurred.

When the image is to be displayed in 256 gradations, the frame period (16.67 ms) corresponding to 1/60 second is divided into eight subfields. Here, the reset period and the address period of each subfield are the same for each subfield, while the sustain period and the number of discharges thereof are 2 ⁿ (n = 0,1,2,3,4,5,6,7) in each subfield. , 8). As described above, since the sustain period is changed in each subfield, gray levels of an image can be realized.

The PDP is driven by enlarging the dynamic range of moving images in order to improve contrast.

1 is a block diagram showing a driving apparatus of a PDP using a dynamic range expansion method according to the prior art.

Referring to FIG. 1, a driving apparatus of a PDP using a dynamic range expansion method according to the related art includes a frame memory 14, lower and upper gray level histogram detectors 22A and 22B, minimum distribution lower and upper gray level value determination units. 24A and 24B, the dynamic range adjusting unit 16, and the PDP driving unit 18 are provided.

The frame memory 14 stores the data from the input line 12 in one frame unit and supplies the data to the dynamic range adjusting unit 16.

The histogram detectors 22A and 22B of the lower and upper gray levels detect the histograms of the lower and upper gray levels for each gray level on the basis of the data from the input line 12 by one frame. This first obtains the overall distribution of each gray level for the input screen of one frame. The histogram H (I), which is a gray level distribution value of the input data, is detected based on the overall distribution. At this time, histograms are mainly detected at gray levels, such as about 0 to 20 gray and 220 to 255, to determine the minimum and maximum gray levels (MIN, MAX).

The minimum distribution lower and upper gray level value determination units 24A and 24B determine an arbitrarily set reference ratio and determine lower and upper gray levels (MIN, MAX) having less gray level distribution through histograms of detected lower and upper gray levels. do.

The dynamic range adjusting unit 16 enlarges the dynamic range of the input data using the data input from the frame memory 14, the minimum distribution lower and upper gray level values. The dynamic range adjuster 16 supplies input data having an enlarged dynamic range to the PDP driver 18.

The PDP driver 18 corrects the digital signal input from the dynamic range adjuster 16 and supplies it to the panel. To this end, the PDP driver 18 includes the first inverse gamma correction unit 32A, the gain control unit 34, the error diffusion unit 36, the subfield mapping unit 38, and the data alignment unit 40 as shown in FIG. And a second inverse gamma correction unit 32B, an average picture value (APL) unit 44, a waveform generator 46, and a panel 48.

The first and second inverse gamma correction units 32A and 32B perform inverse gamma correction on the video signal input from the dynamic range adjusting unit 16 to linearly convert the luminance value according to the gray value of the image signal.

The APL unit 44 receives the video data corrected by the second inverse gamma correction unit 32B and generates an N-stage signal for adjusting the number of sustain pulses. The gain controller 34 amplifies the video signal corrected by the first inverse gamma correction unit 32A by the effective gain.

The error diffusion unit 36 finely adjusts the luminance value by diffusing an error component of a cell into adjacent cells. The subfield mapping unit 38 reallocates the video data corrected by the error diffusion unit 36 for each subfield.

The data aligner 40 aligns the video signal to be supplied to the panel 48, and supplies the video signal to an address driving integrated circuit (IC) not shown.

The waveform generator 46 generates a timing control signal based on the N-stage signal input from the APL unit 44, and converts the generated timing control signal into an address driving IC, a scan driving IC, and a sustain driving IC of the panel 48. Supply.

In detail, the second inverse gamma correction unit 32B first performs inverse gamma correction on the video signal input from the dynamic range adjustment unit 16 and supplies the inverse gamma correction unit to the APL unit 44. The APL unit 44 receiving the inverse gamma corrected video signal generates an N-stage signal for adjusting the number of sustain pulses, and supplies it to the waveform generator 46. The waveform generator 46 generates a timing control signal using the N-stage signal input from the APL unit 44, and supplies the generated control signal to the address driving IC, the scan driving IC, and the sustain driving IC.

The first inverse gamma correction unit 32A performs inverse gamma correction on the video signal input from the dynamic range adjustment unit 16 and supplies it to the gain control unit 34. The gain control unit 34 receiving the inverse gamma corrected video signal amplifies the corrected video signal by an effective gain and supplies it to the error diffusion unit 36. The error diffusion unit 36 error-spreads the video signal input from the gain control unit 34 to finely adjust the luminance value. The video signal output from the error diffusion unit 36 is input to the subfield mapping unit 38. The subfield mapping unit 38 reallocates the error-diffused video data for each subfield and supplies the data to the data alignment unit 40. The data aligner 40 aligns the video signal and supplies it to the address driver IC.

Thereafter, an image corresponding to the video signal is displayed on the panel 48 by the control of the address driving IC, the scan driving IC, the sustain driving IC, and the like. In the driving apparatus of the PDP according to the prior art according to the above configuration, it is possible to obtain a clear image by improving contrast through an enlarged dynamic range.

FIG. 3 is a flowchart illustrating the dynamic range expansion method described with reference to FIG. 1.

Referring to FIG. 3, first, input data RGB from the outside is input to the lower and upper gray level histogram detectors 22A and 22B.

The histogram H (I) of each gray level is detected (S12). This first obtains an overall distribution of gray levels for an input screen of one frame. Based on the overall gray level distribution, the ratio of the histogram, which is the number of distributions of 0 to 255 gray levels, can be known. For example, in a PDP with WVGA (853 * 480) resolution mode, if the number of histograms with 2 grays is 245, the distribution ratio is Becomes When the distribution ratio of each gray level is obtained, the histogram ratio with respect to the input data appears as shown in Tables 1 and 2.

Histogram % Of distribution Hist [0] 0.02 Hist [1] 0.04 Hist [2] 0.06 Hist [3] 0.0 … … Hist [17] 0.03 Hist [18] 0.09 Hist [19] 0.1 Hist [20] One

Histogram % Of distribution Hist [220] 1.0 Hist [221] 0.1 Hist [222] 0.06 Hist [223] 0.001 … … Hist [252] 0.03 Hist [253] 0.02 Hist [254] 0.09 Hist [255] 0.05

Here, the histogram distribution ratio (%) for each gray level may vary depending on the input data for one frame.

Based on the histogram distribution ratio (%), the minimum distribution lower and upper gray levels (MIN, MAX) are determined. (S14) First, before determining the minimum distribution lower and upper gray level values, the threshold value of the histogram distribution ratio (%) is determined. Decide In Figure 3, 0.1% was set as the threshold. This sets the first gray level with 0.1% or more as the minimum distributed lower gray level (MIN) and the minimum distributed upper gray level (MAX). (S18) When the distribution ratio is 0.1% or less, the next histogram distribution ratio is continuously searched. (S16)

Thus, in the case of Table 1 and Table 2, the gray level is determined as the minimum distributed lower gray level MIN is 19 and the minimum distributed upper gray level MAX is 221.

The values of the minimum distribution lower and upper gray levels (MIN, MAX) determined as described above are input to the dynamic range determination unit 16. The dynamic range determiner 16 rearranges the input image by using Equation 1 to input the minimum distribution lower and upper gray levels MIN and MAX.

Where X is the gray level of the input data before correction and Y is the gray level of the input data after correction. In addition, MAX is the value of the minimum distributed upper gray level, and MIN is the value of the minimum distributed lower gray level.

When X is 40, the minimum distribution lower and upper gray level values determined through Table 1 and Table 2 are applied to Equation 1. By Y, the minimum gray level value after correction for X becomes 26.5. This changes the input data of 40 to a lower value of 26.5. That is, in the present invention, as shown in FIG. 4, the histogram distribution I according to the gray level in the dotted line form may be obtained as the histogram distribution II according to the gray level in the solid line form in which the dynamic range is expanded. As a result, as the dynamic range is enlarged, the contrast of the screen is improved to obtain a clear screen. In other words, the bright part is displayed brighter and the dark part is displayed darker, so that the contrast between the bright part and the dark part of the screen can be clearly displayed.

5A and 5B illustrate changes in the display image before and after applying the dynamic range enlargement method. As the contrast of the light and dark of the screen becomes clearer, the dynamic range is enlarged according to the prior art illustrated in FIG. 5B. It can be seen that the image is clearer than that of FIG. 5A.

FIG. 6 is a view for designating a predetermined area for comparing only a part of the display image shown in FIG. 5B, and FIGS. 7A and 7B are views showing a change in histogram distribution after the dynamic range enlargement process according to the prior art. FIG. 8B is a diagram illustrating a change of a display image of a portion of FIG. 6.

7A and 7B, the distribution of the histogram according to the prior art of FIG. 7B is toward the gray level lower than the distribution of the histogram according to the prior art of FIG. 7A by expanding the dynamic range according to the minimum distribution lower and upper gray level values. You can see that it has been moved. As a result, as described above, the darker portions become darker and the brighter portions appear brighter.

Referring to the results of FIGS. 7A and 7B through FIGS. 8A and 8B, first, FIGS. 8A and 8B compare the area A of FIG. 6, and it can be seen that the dark part of the sky becomes darker. Next, FIGS. 9A and 9B compare the area B of FIG. 6 and show a display screen in which a bright part and a dark part coexist. In this case as well, the contrast between the bright and dark areas can be seen that the contrast is improved.

However, according to the conventional method of increasing the dynamic range of the PDP, the contrast in the moving picture is improved due to the brighter and darker parts of the PDP, which are brighter and darker than the original picture. The same problem occurs.

To illustrate this problem, for example, when the gray levels of red (R), green (G), and blue (B) are 205, 20, and 205, respectively, the minimum distribution upper and lower gray levels (MAX) of the input image are shown. , MIN) has the values 215 and 0, respectively.

In this case, the minimum distribution upper gray level MAX, that is, the gray levels 215 and more than 215 is converted as follows when Equation 1 is applied by the dynamic range expansion method. That is, 215 Is converted to 255 by 220 Is converted to 255 by

As shown in FIG. 10, the graph shows the result of the enlargement of the dynamic range as described above. 10 illustrates a gamma output state during gamma processing after dynamic range expansion of an input image according to the prior art. Here, "I" indicates a gamma output state during gamma processing without the dynamic range enlargement process, and "II" shows a gamma output state during gamma process after the dynamic range enlargement process.

In this case, after the dynamic range expansion process according to the prior art, the input image data having the minimum gray level MAX higher than the minimum distribution in the gamma process is all converted to 255. That is, as shown in FIG. 10, when the minimum distributed upper gray level MAX is set to 215, input image data of 215 gray levels or more is saturated to 255. As a result, there is a problem that the gamma output characteristic for each gray level is not provided between 215 and 255 gray levels.

Accordingly, an object of the present invention is to provide an apparatus and method for driving a plasma display panel using a dynamic range magnification method to improve contrast of a display screen by expanding a dynamic range when displaying a moving image.

Another object of the present invention is to drive a plasma display panel using a dynamic range enlargement method to prevent image quality deterioration by differently selecting a minimum distribution upper gray level value according to an input image when processing a moving image display through an expansion of a dynamic range; To provide a way.

1 is a block diagram illustrating an apparatus for driving a plasma display panel using a dynamic range expansion method according to the related art.

FIG. 2 is a block diagram illustrating in detail the PDP driver shown in FIG. 1.

FIG. 3 is a flow chart for explaining the dynamic range expansion method described with reference to FIG. 1.

4 is a diagram showing a histogram distribution change with respect to a gray level according to the prior art.

5A and 5B illustrate changes in the display image before and after applying the dynamic range expansion method.

FIG. 6 is a diagram for comparing only a part of the display image illustrated in FIG. 5B.

7A and 7B illustrate changes in histogram distribution after dynamic range expansion according to the prior art.

8A and 8B illustrate changes in a display image of a portion of FIG. 6.

9A and 9B are diagrams illustrating changes of a display image with respect to another part of FIG. 6.

10 is a graph illustrating a gamma output state during gamma processing after dynamic range expansion of an input image according to the prior art.

11 is a view showing a driving device of the PDP using the dynamic range expansion method according to an embodiment of the present invention.

FIG. 12 is a diagram illustrating a minimum distribution upper and lower gray level restriction unit in FIG. 11.

FIG. 13 is a diagram illustrating a movie data type in a movie format or 4: 3 mode. FIG.

FIG. 14 is a diagram illustrating in detail the minimum and upper gray level detectors of FIG. 11.

15 is a diagram illustrating a method of driving a PDP using the dynamic range expansion method according to an embodiment of the present invention.

FIG. 16 is a diagram illustrating a gamma output state when compensating a gamma curve in the peak compensator of FIG. 11.

<Description of Symbols for Main Parts of Drawings>

12,52 input line 14,54 frame memory

16 dynamic range adjustment unit 18 PDP drive unit

22: gray level histogram detector

24: minimum and lower gray level value determination unit

32,58: reverse gamma correction unit 34,62: gain control unit

36,64: error diffusion unit 38,66: subfield mapping unit

40,68: data alignment unit 44,78: APL unit

46,80 Waveform generator 48,70 Panel

52: minimum distribution upper and lower gray level detector

56 dynamic range converting unit 60 peak compensation unit

62: delay 74: minimum distribution gray level limit

In order to achieve the above objects, the driving apparatus of the plasma display panel using the dynamic range expansion method according to the present invention is a frame memory for storing moving picture data from an external input line in units of frames, and connected between the frame memory and the panel. And a dynamic range converter for converting the dynamic range of the video data according to the minimum distribution lower and upper gray level information, and the video data from the input line in parallel with the frame memory between the input line and the dynamic range converter. A frame which is serially connected to the minimum and lower gray level limiting unit for limiting the minimum and lower gray level and the minimum and lower gray level limiting units according to the form, and is framed according to the gray level limiting information The minimum and lower gray level detectors for detecting the lower and upper gray levels of the minimum distribution, and the dynamic range-converted moving image data connected in series between the dynamic range converter and the panel to reverse gamma correct the video signal. And an inverse gamma correction unit for linearly converting luminance values according to gray scale values.

In the minimum distribution lower and upper gray level limiting portions of the present invention, the moving image data type includes image data having a high gradation level, image data including text and caption broadcasting, and image data having a 4: 3 aspect ratio. It is characterized in that any one of.

In the present invention, in the case of the image data having a high gradation level, the minimum distribution upper gray level is limited to 200 to 230 gray levels or more.

In the present invention, in the case of the image data including the text and the caption broadcasting, gray levels of 252 gray level or more are excluded from the minimum gray level of the highest distribution.

In the present invention, in the case of the image data having an aspect ratio of 4: 3, 0 gray level is excluded from the minimum distribution lower gray level.

In the present invention, a peak compensation for converting a gamma output curve according to a magnitude comparison between data input from the frame memory and gamma correction from the inverse gamma correction unit is connected in series between the inverse gamma correction unit and a panel. And a delayer connected in parallel with the dynamic range converter and inverse gamma correction unit between the frame memory and the peak compensator to delay input data from the frame memory input to the peak compensator for a predetermined time. It is characterized by including.

The minimum and lower gray level detectors of the present invention detect the histogram distribution ratio which is the number of distributions of the lower and upper gray levels after detecting each gray level of the video data during one frame input from the outside. And a histogram detection unit having a level and a minimum distribution lower and upper gray level detection unit connected in series with the histogram detection units of the lower and upper gray levels to determine a minimum distributed lower gray level.

The method for driving a plasma display panel using the dynamic range expansion method according to the present invention includes detecting restriction information of a minimum distribution lower and upper gray levels according to a moving image input image, and using the restriction information, lower limit lower and upper gray levels. Detecting the dynamic range; converting a dynamic range of the input image according to the minimum distribution lower and upper gray level information; and linearly converting a luminance value according to a gray value of the input image converted from the dynamic range. And gamma correction, and compensating the gamma corrected data to have a gamma output curve linearly by comparing the data value of the moving image input image delayed by a predetermined time.

In the present invention, detecting the minimum and lower gray levels of the minimum distribution includes restricting the minimum distributed upper gray level to 215 gray levels or more in the case of the image data having a high gray level, and the character and subtitles. In the case of video data including broadcasting, gray levels of 252 gray level or more are excluded from the minimum gray level. In the case of video data having a 4: 3 aspect ratio, 0 gray level is the lowest gray level. Characterized in steps that exclude from.

The predetermined delay time according to the present invention is characterized in that the data of the moving image input image is converted into the gamma-corrected data after expanding the dynamic range.

Compensating the peak in the present invention includes comparing the magnitude of the gamma corrected data value and the data value of the delayed moving image input image, and applying the data value selected according to the comparison information to a gamma output curve. It is characterized by including.

The step of applying the data value selected according to the comparison information in the gamma output curve comprises selecting the gamma corrected data value when the data value of the delayed moving image input image is greater than or equal to the gamma corrected data value. And selecting a data value of the delayed moving image input image when the data value of the delayed moving image input image is smaller than the gamma corrected data value.

The detecting of the minimum distribution lower and upper gray levels of the moving image input image may include determining the minimum distribution lower and upper gray levels, setting a threshold value for the histogram distribution ratio, and setting the threshold value. And a step of setting the first gray level to be obtained as the minimum distribution lower and upper gray levels.

The step of enlarging the dynamic range of the input image according to the present invention may include determining a gray level of the image data input from the outside, and correcting the image using the gray level, minimum distribution lower and upper gray levels of the input image data. Determining a gray level of the data.

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. 11 to 16.

11 is a view showing a driving device of the PDP using the dynamic range expansion method according to an embodiment of the present invention.

Referring to FIG. 11, a driving apparatus of a PDP using the dynamic range expansion method according to the embodiment of the present invention includes a frame memory 54 for storing red, green, and blue video data from the input line 52, respectively; Dynamic range converter 56, inverse gamma correction unit 58, peak compensation unit 60, gain adjustment unit 62, error diffusion unit 64 connected between the frame memory 54 and the panel 70, A subfield mapping unit 66 and a data alignment unit 68; An APL unit 78 and a waveform generator 80 connected between the peak compensator 60 and the panel 70; A minimum distributed upper / lower gray level limiter 74 and a minimum distributed upper / lower gray level detector 52 connected in parallel with the frame memory 54 between the input line 52 and the dynamic range converter 56; A delay unit 62 is provided between the frame memory 54 and the peak compensator 60 in parallel with the dynamic range converter 56 and the inverse gamma correction unit 58.

The frame memory 54 stores red, green, and blue data from the input line 52 in one frame unit and supplies the data to the delay unit 72 and the dynamic range converter 56.

The minimum distributed upper / lower gray level limiter 74 limits the target data in detecting the minimum distributed upper and lower gray levels with respect to the input data RGB. For this reason, the minimum distributed upper gray level limit unit 74 is a minimum distributed upper gray level limit connected in parallel between the input line 52 and the minimum distributed upper / low gray level detector 76 as shown in FIG. 12. 82A and minimum distributed lower gray level limiting portion 82B. In the present invention, the case of limiting the target data can be represented by three types.

First, the minimum distribution upper gray level (MAX) is defined to prevent color saturation at high gray level input. For example, when the minimum distribution upper gray level MAX is set to 150 in a region where light colors are concentrated, all data of 150 or more are converted to 255. In this case, all gray levels between 155 and 255 are converted to 255, resulting in color saturation, which may be a problem when driving a PDP using dynamic range expansion. Therefore, in the case of the present invention, in order to prevent the above problem, the minimum distribution upper gray level value is set to be 215 or more. As a result, it is possible to obtain a conversion result of an image in which color saturation is prevented and image quality deterioration does not occur when driving the PDP according to the present invention.

Second, in the display image containing subtitles such as a character broadcasting and a digital versatile disc (DVD) player, when the dynamic range is expanded by including the captioned portion when detecting the minimum gray level (MAX), the video data is not subtitles. The dynamic range enlargement process may not be performed. At this time, the subtitle of DVD player usually has 255 gray level value. Therefore, in the case of the present invention, gray levels of 252 or more are configured to be excluded from the minimum distributed upper gray level.

Finally, when the 4: 3 or movie format display image is processed, the dark portions in FIG. 13 do not display the display image and have a specific color. Some particular colors are often black, either RGB or RGB. At this time, when the dynamic range enlargement process is performed up to the dark portions, the display image may not be properly processed. Thus, the present invention is characterized in that the zero gray level is excluded from the minimum distributed lower gray level (MIN).

Through the configuration as described above, the minimum distribution upper / lower gray level limiting unit 74 is the minimum distribution upper and lower gray level (MAX) in the minimum distribution upper and lower gray level limiting units 82A and 82B according to the type of input data. The gray level restriction information is provided to the minimum distribution upper / lower gray level detector 76 so as to limit MIN).

The minimum distribution lower and upper gray level detector 76 includes histogram detectors 84A and 84B of lower and upper gray levels and minimum distribution lower and upper gray level value detectors 86A and 86B, as shown in FIG.

The histogram detectors 84A and 84B of the lower and upper gray levels detect the histograms of the lower and upper gray levels for each gray level on the basis of the data from the input line 52 by one frame. This first obtains the overall distribution of each gray level for the input screen of one frame. The histogram H (I), which is a gray level distribution value of the input data, is detected based on the overall distribution.

The minimum distribution lower and upper gray level value detectors 86A and 86B determine an arbitrarily set reference ratio and determine lower and upper gray levels MIN and MAX having less gray level distribution through histograms of the detected lower and upper gray levels. . At this time, the minimum distribution lower and upper gray level value detectors 86A and 86B may perform the minimum distribution upper and lower gray level values MAX and MIN according to the restriction information input from the minimum distribution upper and lower gray level limiting unit 74. Will be determined. The lower and upper gray levels (MIN, MAX) with less determined gray level distribution are supplied to the dynamic range converter 56.

The dynamic range converter 56 serves to maintain and expand the dynamic range of the input data via the frame memory 54 in accordance with the expression power at the minimum gray level or less. As a result, the dynamic range converter 56 expands the dynamic range using the minimum distribution lower and upper gray level values MIN and MAX as input data. The input data of which the dynamic range is enlarged is supplied to the inverse gamma correction unit 58.

The inverse gamma correction unit 58 inversely gamma corrects the video signal input from the dynamic range converter 56 to linearly convert the luminance value according to the gray value of the video signal. In this case, it has a gamma output curve as shown in FIG. 10 in the prior art. The luminance value according to the linearly converted gray value is supplied to the peak compensator 60.

The delay unit 72 receives input data via the frame memory 54 and delays the input data for a predetermined time. The delay unit 72 delays the input data supplied to the dynamic range converter 56 until it is input to the peak compensator 60 through the inverse gamma correction unit 58.

The peak compensator 60 compares the gamma output value gamma corrected by the inverse gamma correction unit 58 with input data including luminance information delayed by the delay unit 72, and selectively outputs the gray level value according to the gray level to compensate for the peak. Determine the value. This peak compensation value is supplied to the gain control unit 62 and the APL unit 78.

The APL unit 78 receives the video data compensated by the peak compensator 60 and generates an N-stage signal for adjusting the number of sustain pulses. The gain controller 62 amplifies the video data compensated by the peak compensator 60 by the effective gain.

The error diffusion unit 64 finely adjusts the luminance value by diffusing an error component of a cell into adjacent cells. The subfield mapping unit 66 reallocates the video data corrected by the error diffusion unit 64 for each subfield.

The data aligner 68 aligns the video signal to be supplied to the panel 70, and supplies the video signal to an address driving integrated circuit (IC) not shown.

The waveform generator 80 generates a timing control signal based on the N-stage signal input from the APL unit 78 and converts the generated timing control signal into an address driving IC, a scan driving IC, and a sustain driving IC of the panel 70. Supply.

15 is a diagram illustrating a method of driving a PDP using the dynamic range expansion method according to an embodiment of the present invention.

The driving method of FIG. 11 will be described with reference to FIG. 15. First, the minimum distribution gray level according to input data is limited (S31). That is, as described above, high gray level, text and caption broadcasting, and 4: 3 ratio display are shown. When using the device, the gray levels for the portions where the video is not displayed are limited so that they are not affected when the dynamic range of the video is expanded.

Based on the minimum distribution gray level restriction information, the minimum and upper gray levels MAX and MIN are detected (S32).

Next, the dynamic range of the input data is converted (S33). The dynamic range of the input data uses the minimum distributed lower and upper gray level values (MIN, MAX) detected by the minimum distributed lower and upper gray level detectors 76. To expand the dynamic range.

The input data of which the dynamic range is enlarged is input to the inverse gamma correction unit 58 to perform gamma correction. (S34) When gamma correction is performed, the luminance value according to the gray value of the image signal is linearly converted.

After the gamma correction, the upper gray level gamma curve is compensated. (S35) This compares the gamma output value gamma corrected from the inverse gamma correction unit 58 with the input data including the luminance information delayed by the delay unit 72 and adjusts the gray scale. The output signal is selectively output to determine the peak compensation value formed of the gamma output curve. That is, if the input data value including the delayed luminance information is greater than or equal to the gamma output value, the gamma output value is determined as the peak compensation value. This is determined. These determined peak compensation values determine a new gamma output curve.

Referring to FIG. 16, first, a gamma output value in FIG. 10 and a linear luminance information data value input from the frame memory 54 are compared. Thus, based on the "B" area, the input data value including the delayed luminance information is equal to or larger than the gamma output value so that the gamma output value is determined as the peak compensation value, and the "B" area or less is delayed. The input data value including the luminance information is smaller than the gamma output value, and the linear luminance information data value is determined as the peak compensation value. That is, the gray level below the "B" area is used as the gamma curve after dynamic range expansion, and the input data value is output as it is at the gray level above the "B" area.

In operation S35, the gamma output curve is converted as shown in FIG. 16, and then the gain is controlled (S36). The gain controller 62 amplifies the peak-compensated video signal by the effective gain. Thereafter, the error-diffused luminance value is finely adjusted, and the error-diffused video data is re-allocated for each subfield and supplied to the data alignment unit 68. The data alignment unit 68 aligns the video signal and supplies it to the address driver IC.

As described above, the driving apparatus and method of the plasma display panel using the dynamic range expansion method according to the present invention detects the minimum distribution upper and lower gray level values by limiting the gray scale which is not considered when the dynamic range is enlarged according to the moving image input image. do. Accordingly, the driving apparatus and method of the plasma display panel using the dynamic range expansion method according to the present invention can improve contrast and display a clear video.

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 (20)

A frame memory for storing video data from an external input line in units of frames, A dynamic range converting unit connected between the frame memory and the panel to convert the dynamic range of the video data according to minimum distribution lower and upper gray level information; A minimum distribution lower and upper gray level limiter connected in parallel with the frame memory between the input line and the dynamic range converter to limit the minimum and lower gray levels according to the type of moving picture data from the input line; A minimum distributed lower and upper gray level detector serially connected to the minimum distributed lower and upper gray level limiters and detecting the minimum distributed lower and upper gray levels for one frame according to the gray level limit information; And an inverse gamma correction unit linearly connected between the dynamic range converting unit and the panel to inversely gamma correct the dynamic range converted video data to linearly convert luminance values according to grayscale values of the image signal. An apparatus for driving a plasma display panel using a dynamic range expansion method. The method of claim 1, The video data type in the minimum and lower gray level limiting units may be one of image data having a high gradation level, image data including text and caption broadcasting, and image data having a 4: 3 aspect ratio. A driving apparatus of a plasma display panel using a dynamic range expansion method, characterized in that. The method of claim 2, In the case of the image data having a high gradation level, the plasma display panel driving apparatus using the dynamic range expansion method, characterized in that the minimum distribution upper gray level is limited to 200 to 230 gray levels or more. The method of claim 3, wherein In the case of the image data having a high gradation level, the minimum distribution upper gray level is about 215 gray levels. The method of claim 2, In case of the image data including the text and the caption broadcasting, gray level of 252 gray level or higher is excluded from the minimum gray level of the highest distribution. The method of claim 2, An apparatus for driving a plasma display panel using a dynamic range expansion method, wherein 0 gray levels are excluded from a minimum distribution lower gray level in the case of image data having an aspect ratio of 4: 3. The method of claim 2, A peak compensation unit connected in series between the inverse gamma correction unit and the panel to convert a gamma output curve according to a magnitude comparison between data input from the frame memory and gamma correction from the inverse gamma correction unit; And a delayer connected in parallel with the dynamic range converter and an inverse gamma correction unit between the frame memory and the peak compensator to delay input data from the frame memory input to the peak compensator for a predetermined time. A driving apparatus for a plasma display panel using a dynamic range expanding method. The method of claim 1, The minimum distribution lower and upper gray level detection unit detects each gray level of the video data during one frame input from the outside, and then the histogram detection unit of the lower and upper gray level detecting the histogram distribution ratio which is the distribution number of the lower and upper gray levels. Wow, And a minimum distributed lower and upper gray level detector connected in series with the lower and upper gray level histogram detectors to determine a minimum distributed lower gray level. The method of claim 7, wherein And the retarder delays the input data via the frame memory during the time that the input data passes through the dynamic range converting unit and the inverse gamma correcting unit. The method of claim 7, wherein A gain controller for amplifying the video signal via the peak compensation unit by an effective gain; An error diffusion unit for finely adjusting the luminance value by diffusing an error component of the cell into adjacent cells; A subfield mapping unit for reallocating the video data corrected by the error diffusion unit for each subfield; And a data alignment unit for aligning the video signal to be supplied to the display panel. The method of claim 10, An average image value (APL) unit for receiving an video signal via the peak compensation unit and generating an N-stage signal for adjusting the number of sustain pulses; And a waveform generator for generating a timing control signal based on the N-stage signal input from the average image value unit and supplying the generated timing control signal to a driving integrated circuit of the display panel. An apparatus for driving a plasma display panel using the same. Detecting restriction information of the minimum distribution lower and upper gray levels according to the moving image input image; Detecting a minimum distribution lower and upper gray levels through the restriction information; Converting a dynamic range of the input image according to the minimum distribution lower and upper gray level information; Gamma correction to linearly convert a luminance value according to a gray value of the input image having the converted dynamic range; And compensating for a peak to linearly have a gamma output curve by comparing the gamma corrected data value with a predetermined time delayed video input image. Way. The method of claim 12, The detecting of the minimum distribution lower and upper gray level restriction information may include: Limiting the minimum distributed upper gray level to 215 gray levels or more for the image data having a high gray level; In the case of the image data including the text and the caption broadcasting, grey levels of 252 gray level or more are excluded from the minimum gray level of the highest distribution; A method of driving a plasma display panel using a dynamic range expansion method, characterized in that 0 gray level is excluded from a minimum distribution lower gray level for image data having an aspect ratio of 4: 3. The method of claim 12, And the predetermined delay time is a time for converting the data of the moving image input image into the gamma corrected data after expanding the dynamic range. The method of claim 12, Compensating the peak may include comparing the magnitude of the gamma corrected data value and the data value of the delayed moving image input image; And applying a data value selected according to the comparison information to a gamma output curve. The method of claim 15, The step of applying the data value selected according to the comparison information to the gamma output curve includes selecting the gamma corrected data value when the data value of the delayed moving image input image is greater than or equal to the gamma corrected data value; And selecting a data value of the delayed moving image input image when the data value of the delayed moving image input image is smaller than the gamma corrected data value. The method of claim 12, The detecting of the minimum and lower gray levels of the minimum distribution for the moving image input image may include determining the minimum and lower gray levels of the minimum distribution, and setting a threshold for the histogram distribution ratio. And setting the first gray level coming out above the threshold to a minimum distribution lower and upper gray level. The method of claim 12, The step of enlarging the dynamic range of the input image may include determining a gray level of image data input from the outside; And determining a gray level of the image data corrected using the gray level, the minimum distribution lower and upper gray levels of the input image data. The method of claim 12, Amplifying the peak compensated video signal by an effective gain; Finely adjusting a luminance value by error diffusion of the amplified video signal; And reallocating the error-diffused video signal for each subfield to supply the panel to the panel. The method of claim 19, Generating an N-stage signal for adjusting the number of sustain pulses by receiving the linearly converted signal; And generating a timing control signal by using the input N-stage signal, and supplying the generated control signal to a driving circuit.