KR100684728B1 - Plasma display device and driving method therof - Google Patents

Abstract

A plasma display device and a driving method thereof are provided to maintain uniform contrast of a displayed image, even when the number of sustain pulses is varied, by automatically forming a gamma curve according to an APC(Automatic Power Control) level. A plasma display device includes a PDP(Plasma Display Panel,100) and a controller(200). Plural discharge cells are formed on the PDP. The controller generates a control signal for driving the PDP and compensates for first image data according to the characteristics of the PDP. The controller determines an APC level corresponding to the load ratio of the first image data, calculates a final gain value, which is proportional to the APC level based on a predetermined gain value, and generates a gain curve by using a first function. The controller generates a first gamma curve by multiplying a basic gamma curve with the gain curve and generates compensated second image data by applying the first image data to the first gamma curve. The basic gamma curve is formed by using an image gamma value as an index.

Description

Plasma display device and driving method thereof {PLASMA DISPLAY DEVICE AND DRIVING METHOD THEROF}

1 is a diagram illustrating a plasma display device according to an exemplary embodiment of the present invention.

2 is a block diagram illustrating an internal configuration of the controller 200 in the plasma display device according to the exemplary embodiment of the present invention.

3 is a block diagram showing the internal configuration of the gamma correction unit 210 according to an embodiment of the present invention.

4 is a diagram illustrating a basic gamma curve that is variously generated according to an image gamma value in the image gamma corrector 212.

5 is a diagram illustrating a gain curve generated by the gain curve generator 214.

FIG. 6 is a diagram illustrating a modified gamma curve generated by the gamma curve calculator 216 according to an embodiment of the present invention.

7 is a diagram illustrating R, G, B correction curves for the effective sustain ratios of R, G, and B, respectively.

8 illustrates a final gamma curve according to an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display device and a driving method. More particularly, the present invention relates to a plasma display device and a driving method thereof for correcting a panel gamma according to an automatic power control (APC) level.

Recently, flat display devices such as liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs) and the like have been actively developed. Among these flat panel display devices, the plasma display device has advantages of higher luminance and luminous efficiency and a wider viewing angle than other flat panel display devices. Therefore, the plasma display device is in the spotlight as a display device to replace the conventional cathode ray tube (CRT) in a large display device of 40 inches or more.

In such a plasma display device, in order to realize a natural image, it is necessary to correct white linearity so that a white color coordinate is constant. In general, a green (G) signal is more than a red (R) and blue (B) signal. Since the luminous efficiency is high, white linearity is corrected by correcting this in advance on the input side. For example, if the emission rate of R, G, B of the PDP is R: G: B = 0.6: 1: 0.3, R, B based on the B signal having the lowest luminous efficiency to realize the same luminance level. The output is corrected to adjust the signal downward to achieve an overall color balance.

However, in order to correct the linearity of the plasma display device, a plurality of RGB panel gamma correction tables store gamma correction values corresponding to APC levels, respectively. At this time, after determining the section to which the input APC level belongs, the two panel correction tables to which the section belongs respectively are selected and interpolation operation is performed on the gamma correction value corresponding to each input data output from the two correction tables. To output correction data (R ', G', B ') corresponding to an arbitrary APC level.

However, according to the conventional panel gamma correction method, since a correction table needs to be applied for each APC level, the memory storage capacity of the controller increases, which causes a problem that the panel gamma correction speed is also lowered.

The technical problem to be achieved by the present invention is to solve the problems of the prior art as described above, the present invention by generating a plurality of gamma curve for each APC level for each of R, G, B using one basic gamma curve The present invention relates to a plasma display device and a method of driving the same, which can simply perform gamma correction.

According to an aspect of the present invention for achieving the above object, a plasma display panel for forming a plurality of discharge cells; And a control unit for generating a control signal for driving the plasma display panel and correcting the input first image data according to the characteristics of the plasma display panel. In this case, the controller calculates a load ratio of the input first image data, determines an automatic power level corresponding thereto, generates a first gamma curve corresponding to the automatic power level, and converts the first image data into the first image data. The corrected second image data is generated in correspondence with one gamma curve. In addition, a first curve corresponding to the automatic power level is generated, and the first gamma curve is generated by reflecting the first curve to a basic curve.

According to another aspect of the present invention, in the plasma display device for correcting and displaying input first image data, in a method of driving one field into a plurality of subfields, the load ratio of the first image data is calculated and Determining an automatic power level value corresponding thereto; Receiving an automatic power level value and generating a first curve corresponding thereto; Generating a first gamma curve by reflecting the first curve to a predetermined basic gamma curve; Generating corrected second image data by corresponding the input first image data to the first gamma curve; And displaying the second image data on the plasma display device.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like reference numerals designate like parts throughout the specification.

A plasma display device and a driving method thereof according to an embodiment of the present invention will now be described in detail.

First, a schematic structure of a plasma display device according to an exemplary embodiment of the present invention will be described in detail with reference to FIG. 1.

1 is a diagram illustrating a plasma display device according to an exemplary embodiment of the present invention.

As shown in FIG. 1, a plasma display device according to an exemplary embodiment of the present invention includes a plasma display panel 100, a controller 200, an address electrode driver 300, a scan electrode driver 400, and a sustain electrode driver 500. It includes.

The plasma display panel 100 includes a plurality of address electrodes A1 to Am extending in the vertical direction, and a plurality of sustain electrodes X1 to Xn and scan electrodes Y1 to Yn extending in pairs in the horizontal direction. Include. The sustain electrodes X1 to Xn are formed corresponding to the scan electrodes Y1 to Yn, and generally have one end connected to each other in common. The plasma display panel 100 includes a substrate (not shown) on which the sustain and scan electrodes X1 to Xn and Y1 to Yn are arranged, and a substrate (not shown) on which the address electrodes A1 to Am are arranged. The two substrates are disposed to face each other with the discharge space therebetween so that the scan electrodes Y1 to Yn and the address electrodes A1 to Am and the sustain electrodes X1 to Xn and the address electrodes A1 to Am are orthogonal to each other. At this time, the discharge space at the intersection of the address electrodes A1 to Am and the sustain and scan electrodes X1 to Xn and Y1 to Yn forms a discharge cell. The structure of the plasma display panel 100 is an example, and a panel having another structure to which the driving waveform described below may be applied may also be applied to the present invention.

The controller 200 receives an image signal from the outside and outputs an address electrode A driving control signal, a sustain electrode X driving control signal, and a scan electrode Y driving control signal. The controller 200 controls to drive a frame by dividing a frame into a plurality of subfields, and the gray level is expressed by the combination of the subfields.

In addition, the controller 200 receives an APC level value from the APC level determiner with respect to an image signal received from the outside and performs a gamma correction corresponding thereto.

The address electrode driver 300 receives the address electrode A driving control signal from the controller 200 and applies a display data signal for selecting a discharge cell to be displayed to each address electrode.

The scan electrode driver 400 receives the scan electrode Y driving control signal from the controller 200 and applies a driving voltage to the scan electrode Y.

The sustain electrode driver 500 receives the sustain electrode X driving control signal from the controller 200 and applies a driving voltage to the sustain electrode X.

Next, a method of performing gamma correction in the controller 200 of the plasma display device according to an exemplary embodiment of the present invention will be described.

2 is a block diagram illustrating an internal configuration of a controller 200 of a plasma display device according to an exemplary embodiment of the present invention.

As shown in FIG. 2, the control unit 200 of the plasma display device according to an exemplary embodiment of the present invention includes a gamma correction unit 210, an error diffusion unit 220, an address data generator 230, and an APC level determiner. And a sustain scan pulse generator 250.

The gamma correction unit 210 generates a gamma curve corresponding to the APC level value input from the APC level determiner 240, and inputs external image data R, G, and B using the generated gamma correction curve. Gamma correct.

Since the bit of the data output from the gamma correction unit 210 exceeds the bit of the data that can be represented by the actual plasma display device, the error diffusion unit 220 diffuses the excess bit into the surrounding pixels. Error diffusion is a method of displaying an image of an excess bit by separating an image of a bit to be diffused into adjacent pixels, and a detailed description thereof is described in Korean Laid-Open Patent Publication No. 2002-0014766.

The address data generator 230 generates address data corresponding to the corrected R ', G', and B 'data and applies them to the address electrode driver 300, the scan electrode driver 400, and the sustain electrode driver 500, respectively. do.

The APC level determiner 240 receives external image data R, G, and B to determine an APC level value of the plasma display device, and refers to an average signal level (hereinafter referred to as 'ASL') detector ( 242 and an APC level calculator 244.

In this case, the APC level means the amount of power consumed when driving one frame in driving the plasma display device, and the power consumption is controlled by adjusting the number of sustain pulses according to the size of the APC level. do.

The ASL detector 242 detects an average signal level from the inputted R, G, and B data.

Here, the calculation of ASL for each frame is calculated by Equation 1 below.

In Equation 1, R _{x , y} , G _{x , y} , B _{x , y} are R, G, B gray scale values in discharge cells at (x, y) positions, respectively, and N and M are horizontal and vertical frames, respectively. Is the size.

The APC level calculator 244 calculates the APC level required for driving the plasma display device, that is, the number of sustain pulses, based on the average signal level output from the ASL detector 242.

The sustain scan pulse generator 250 receives corrected R ', G', and B 'data, generates sustain pulses and scan pulses corresponding to the corrected data, and generates the address electrode driver 300 and the scan electrode driver 400. ) And the sustain electrode driver 500.

Hereinafter, a method of generating a plurality of gamma curves by the gamma correction unit 210 according to an embodiment of the present invention corresponding to the APC level values input from the APC level determiner 240 will be described.

That is, a method of outputting a signal corrected by the gain value determined by the APC level value in the gamma correction unit 210 will be described in detail with reference to FIGS. 3 to 8.

3 is a block diagram showing an internal configuration of a gamma correction unit 210 according to an embodiment of the present invention.

As shown in FIG. 3, the gamma correction unit 210 according to an exemplary embodiment of the present invention includes an image gamma generator 212, a gain curve generator 214, a gamma curve calculator 216, and a sustain classifier 217. ) And the final gamma curve generator 218.

First, FIG. 4 is a diagram illustrating a plurality of basic gamma curves corresponding to image gamma values in the image gamma generator 212.

The image gamma generator 212 generally corrects the nonlinearity of the display and human vision so that gray gray levels can be continuously displayed visually. When displaying an image signal input from an external device using a plasma display device, image gamma correction should be performed on the input image signal. This is because the monitor characteristics of CRTs, which are mainly used, have a characteristic that the input signal and the output signal do not have a proportional relationship but have a property that is proportional to the γ power, so that the broadcasting station transmits the pre-compensated television signal in consideration of this. . Accordingly, the image gamma generator 212 according to an embodiment of the present invention re-calibrates the inversely corrected broadcast signal based on Equation 2 to linearly increase the luminance.

Here, x is an input video signal level, y is an output signal level, and γ is a gamma coefficient, that is, an image gamma value. Usually the γ value is between 1.8 and 2.2.

Since gamma correction normally requires an exponential operation, the image gamma generator 212 according to an exemplary embodiment of the present invention uses an lookup table to map an input signal and a corresponding correction signal.

In FIG. 4, by applying the gamma value from 2.0 to 2.3 in units of 0.1, various gamma curves generated in various ways may be represented, and a basic gamma curve having an S shape may be represented. That is, three-dimensional gamma curves of various types may be formed according to the gamma value applied by the image gamma generator 212. In general, as the gamma value increases, a gamma curve having a more steep slope is formed.

Accordingly, the image gamma generator 212 according to an embodiment of the present invention generates a plurality of basic gamma curves of the output gray level of the corrected signal with respect to the input gray level of the image data, and outputs the plurality of basic gamma curves to the gamma curve calculator 216.

Hereinafter, a process of generating a final gamma curve from the basic gamma curve generated by the image gamma generator 212 will be described.

5 to 8 illustrate a process of generating a final gamma curve from the basic gamma curve rotor according to the present invention.

5 is a diagram illustrating a gain curve generated by the gain curve generator 214.

First, the APC level determiner 240 outputs the calculated APC level value to the gain curve generator 214.

At this time, the gain curve generation unit 214 receives the APC level value APC_LEVEL and obtains the final gain value Gain_f using the gain value previously input from Equation 3 below as the initial gain value Gain.

At this time, Pol determines positive signs and negative signs, and VIAS is an index for determining a slope.

As shown in Equation 3, if the APC level input from the APC level calculator 720 is 0 level, the initial gain value immediately becomes the final gain value Gain_f.

However, if the APC level is not zero, the final gain value Gain_f is generated as a new value different from the initial gain value Gain.

A gain curve corresponding thereto is generated using the final gain value Gain_f generated in this manner as the gain values Y ₀ , Y ₁ , Y ₂ , and Y ₃ shown in Equation 4 below.

Here, x represents a value obtained by normalizing the gray ratio, and represents a standardized gray scale value represented by 1.

With respect to Equation 4, when four gain values Y ₀ , Y ₁ , Y ₂ , and Y ₃ are input, Equation 4 is determined. In particular, when 1 is substituted for Y ₀ , Y ₁ , Y ₂ , and Y ₃ as gain values, a basic gain curve of y = 1 is generated as shown in the graph of FIG. 5 (a). At this time, the gain value Y ₀ of Equation 4 , Y ₁ , Y ₂ , and Y ₃ affect the output value y when the input values x are about 0, 0.3, 0.6, and 1.0, respectively.

Therefore, when the input values x0, x1, x2, and x3 are about 0, 0.3, 0.6, and 1, respectively, the gain values Y ₀ , Y ₁ , Y ₂ , Y ₃ The output values y0, y1, y2, y3 corresponding to each of x0, x1, x2, and x3 are changed. Therefore, four points (x0, y0), (x1, y1), (x2, y2), and (x3, y3) are determined according to APC level values.

Accordingly, four points (x0, y0), (x1, y1), (x2, y2), and (x3, y3) determined by APC level values are interpolated and interpolated, as shown in FIG. New gain curves can be implemented. In this case, the method of interpolation may be easily implemented by those skilled in the art, so a detailed description thereof is omitted.

Meanwhile, the gamma curve calculator 216 generates a modified gamma curve as shown in FIG. 6 by applying the basic gamma curve output from the image gamma generator 212 and the gain curve generated by the gain curve generator 214. .

6 illustrates a modified gamma curve generated by the gamma curve calculator 216 according to an embodiment of the present invention.

That is, when the basic gamma curve generated by the image gamma generator 212 is multiplied with the gain curve generated by the gain curve generator 214 as shown in FIG. 5, a modified gamma curve can be obtained as shown in FIG. 6. . At this time, in multiplication, the predetermined coefficient may be further extended.

Therefore, a modified gamma curve may be generated according to the input APC level value.

That is, in the gain curve generator 214 according to the final gain value Gain_f, as shown in FIG. The value is determined.

On the other hand, since the light emission characteristics are different for each of R, G, and B, the gamma curve may be deformed according to the mixing ratio of R, G, and B.

Therefore, the final gamma curve may be generated by considering R, G, and B values corresponding to the effective sustain ratio.

The sustain classifier 217 receives the current APC level value from the APC level determiner 240 and generates R, G, and B correction curves for the effective sustain ratios of R, G, and B, respectively.

FIG. 7 is a diagram illustrating R, G, and B correction curves for effective sustain ratios of R, G, and B generated by the sustain classification unit 217.

In general, when the APC level is low, the screen load is minimal, and the number of sustain pulses is large. On the contrary, when the APC level is high, the screen load is large and the number of sustain pulses is small.

That is, in the entire frame, as the number of cells having a higher gray level is included, the number of maximum sustain pulses used is smaller because the APC level is increased, and conversely, as the number of cells having a lower gray level is included, the APC level is smaller and used. The maximum number of sustain pulses becomes large.

In addition, since the ratio used for each of R, G, and B constituting the entire screen is different, luminance should be corrected for each of R, G, and B. Therefore, the ratio of effective sustain for each of R, G, and B is calculated according to the APC level using Equation 5 as follows.

In Equation 5, Max Sustain means the total number of sustain pulses allocated in one frame when the load is the smallest, and Sustain means the number of sustain pulses allocated in the current frame. do.

In addition, the maximum gradation (Max Data) means the total gradation value generated during one frame in one discharge cell, and R, G, B gradation (Data (R or G or B)) is R, G, B among the entire gradations. Refers to the gradation value each occupies.

That is, for each discharge cell, R, G, and B are respectively selected from the effective sustain ratio value and the total gray scale (Max Data), which discharge cells are selected in the address period substantially for the total number of sustain pulses, causing sustain discharge. The effective sustain ratio is obtained for each of R, G, and B by multiplying the ratio of gray (Data (R or G or B)) to occupy.

At this time, since R, G, and B have different luminous efficiencies, R, G, and B correction values are obtained for four effective sustain ratios and interpolated to obtain a correction curve as shown in FIG. In this case, the R, G, and B correction values are values representing ratios of light emission efficiency of R, G, and B as relative values. Therefore, as shown in FIG. 7, the R, G, and B correction curves can be obtained for the effective sustain ratios of R, G, and B, respectively.

8 illustrates a final gamma curve according to an embodiment of the present invention.

The final gamma curve is generated by multiplying the modified gamma curve in FIG. 7 with the R, G, B correction values corresponding to the effective sustain ratio in the R, G, B correction curves in FIG.

Accordingly, as shown in FIG. 8, a plurality of final gamma curves for each of R, G, and B may be obtained through the APC level value input from the APC level determiner from the basic gamma curve indicated by dotted lines.

As such, the gain value is determined according to the APC level value in the gamma correction unit 210 of the plasma display device according to the exemplary embodiment of the present invention, thereby generating a final gamma curve for each of R, G, and B from the basic gamma curve.

Accordingly, when the external image data R, G, and B are input to the gamma correction unit 210, the corrected signals R ', G', and B 'are output in correspondence with the final gamma curve in FIG.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

For example, although the error diffusion unit 220 is used in the embodiment of the present invention shown in FIG. 2, the error diffusion unit 220 may not be used when the number of sustain pulses belonging to each subfield is optimized. have.

In addition, although the gain curve generator 214 connects four points to interpolate to generate a gain curve, the gain curve generator 214 does not necessarily need to be limited to four points, and more accurate gamma curves can be obtained by interpolating the points.

As described above, according to the present invention, since the gamma curve is automatically generated according to the APC level, the contrast can be uniformly compensated even if the number of sustain pulses is changed.

In addition, since a variety of gamma curves for each APC level may be implemented using one basic gamma curve, the memory storage capacity of the controller of the plasma display device may be reduced.

Claims (9)

delete A plasma display panel forming a plurality of discharge cells; A control unit for generating a control signal for driving the plasma display panel and correcting the input first image data according to the characteristics of the plasma display panel; The control unit, The automatic power level corresponding to the load ratio is determined by the load ratio of the input first image data, and the final gain value is calculated after calculating a final gain value proportional to the magnitude of the determined automatic power level based on a set gain value. A gain curve is generated through a set first function, and a first gamma curve is generated by multiplying the set basic gamma curve and the gain curve, and corrected by corresponding the first image data to the first gamma curve. Generate video data, The basic gamma curve is generated by using an image gamma value as an exponent. delete delete delete In a plasma display device for correcting and displaying input first image data, a method of driving one field divided into a plurality of subfields is provided. Calculating a load ratio of the first image data and determining an automatic power level value corresponding thereto; Calculating a final gain value proportional to an automatic power level value based on the set gain value; Generating a gain curve through a set first function using the calculated final gain value as a variable; Generating a first gamma curve by reflecting the gain curve in a set basic gamma curve; Generating corrected second image data by corresponding the input first image data to the first gamma curve; And And displaying the second image data on the plasma display device. The method of claim 6, And the basic gamma curve is generated by using an image gamma value as an exponent. delete delete

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