WO2020050522A1

WO2020050522A1 - Method and system for correcting brightness of led display

Info

Publication number: WO2020050522A1
Application number: PCT/KR2019/010555
Authority: WO
Inventors: 노희경; 엄용인; 홍성민; 방정호
Original assignee: 주식회사 루멘스
Priority date: 2018-09-07
Filing date: 2019-08-20
Publication date: 2020-03-12

Abstract

Disclosed are a method and a system for correcting the brightness of an LED display having arrayed thereon a plurality of pixels in which a first LED, a second LED, and a third LED form one pixel. The method for correcting the brightness of the LED display comprises the steps of: (a) obtaining pixel data for each position at different positions in front of the LED display; (b) determining a reference value for each position at each of the pixel data for each position; (c) determining correction coefficients for each position with respect to each of the pixels on the basis of the reference value for each position; and (d) combining the correction coefficients for each position with a predetermined ratio and applying the correction coefficients to all of the pixels of the LED display.

Description

Method and system for luminance correction of LED display

The present invention relates to a method and a system for correcting luminance of an LED display, and specifically, to a technique for correcting a luminance deviation occurring for each position in an LED display and viewing a clear image from various angles of the LED display.

In addition, the present invention relates to a technique for improving the expressiveness, uniformity of the LED display and the overall display quality.

In addition, the present invention relates to an LED display driver IC and a method for adjusting luminance of an LED display using the same, and specifically, improving the display quality by improving the luminance expression of the LED display device and reducing the flicker phenomenon in the LED display device. It is related to the technology.

The display device market is mainly composed of LCDs and OLEDs. Recently, LED display devices that implement full-color by allowing a plurality of LED chips to form one pixel are continuously being developed. Many micro LED display devices have been developed to increase the resolution by making the size of an LED chip within a pixel within a few hundred micrometers or 100 micrometers.

When viewing an image displayed on the LED display, there is a difference in luminance for each position where the LED display device is viewed, such as a left position, a center position, or a right position, based on the center of the LED display device, so that the display viewer can achieve optimal uniformity. There is a problem that it is difficult to watch an image.

That is, the LED chips constituting one pixel in the LED display are classified according to characteristics such as luminosity and applied to the LED display, but there is a problem in that a luminance difference is displayed at specific locations when displaying an image. A solution to solve the problem is required in the art.

On the other hand, conventionally, in order to improve the image quality of the LED display, a method of correcting a region having maximum brightness for each red, green, and blue LED of each pixel has been used by using light measurement equipment. That is, the maximum luminance-related light information (for convenience, referred to as a 'maximum luminance value') is measured for each LED of each pixel using an optical measurement device, and the maximum luminance values of the measured LEDs are compared, and these maximum luminance values are compared. Among them, the minimum value is extracted. Then, based on the extracted minimum value, the maximum luminance values are adjusted to have the minimum value. For example, when this process is performed for red LEDs in pixels, the maximum luminance values of the red LEDs are adjusted to have the minimum value. That is, the maximum luminance values of the red LEDs are adjusted to have the extracted minimum value as the new maximum luminance value. The same is true for green LEDs and blue LEDs.

In this way, in the method of correcting only the area having the maximum luminance for the LEDs in the pixels, as described above, after extracting the minimum value among the maximum luminance values, the maximum luminance values are set to the minimum value based on the extracted minimum value. Since there is only a process, since the correction of an area or a middle area having a low gray level in the LEDs in the pixels is not performed, there is a limit in improving the overall image quality of the LED display. Therefore, a method for solving this limitation is required in the art.

On the other hand, LED display devices are continuously being used for indoor and outdoor electronic displays and digital signage. Furthermore, as the development of micro LEDs is accelerated, high-resolution full-color LED displays are being produced in various sizes.

26 is a view schematically showing a drive IC 20 for driving LEDs in pixels arranged in a matrix on the display unit 10 in a general LED display device. In FIG. 26, only one driver IC 20 and the display unit 10 connected thereto are briefly illustrated. As illustrated in FIG. 26, through an appropriate combination of a gray scale clock signal GCLK, a data clock signal DCLK, and a latch enable signal LE, corresponding to an input image source, that is, an input image signal, In order to display an image corresponding to the input image signal in the array of pixels, an optimized control signal for adjusting the current flow and luminance of the LEDs in each pixel is applied. In the driver IC 20, a circuit unit (currently referred to as a switching element) is provided for current sinking for each column of pixels, and a pulse width modulation (PWM) signal is generally used as a control signal. The luminance of each of the LEDs in the pixel is adjusted such that the pulse width modulated signal corresponds to the gray level of the input image signal. Some examples of the pulse width modulated signal corresponding to the gradation of the input video signal are shown in FIG. 27.

In a conventional LED display device such as a billboard or digital signage, high resolution or more accurate color representation was not necessary, so the driver IC uses LEDs generated by pulse width modulation (PWM) to generate the LEDs in the pixels. It was also configured to control the current flowing through it, and it was sufficient to adjust the luminance corresponding to the input video signal. That is, as illustrated in FIG. 28, for an input image signal S _{s in} a low grayscale region of less than 30%, corresponding to a gradation of the input image signal S _s , a duty ratio corresponding thereto ) Using a pulse width modulation signal C _s (for example, the leftmost pulse width modulation signal among the square waves in FIG. 3, and only one period, that is, one pulse width) is used. , A pulse width modulation signal C _s having a duty ratio corresponding to the input image signal S _s in the gradation region of 30% or more and less than 80% (for example, among the square waves in FIG. 28) , A pulse width modulation signal in the center, which shows only one pulse width), and a pulse width having a duty ratio corresponding to the input image signal S _s even for a gradation region of 80% or more. Modulation signal (Cs) (e.g., among the square waves of Figure 28, the rightmost pulse width modulation signal, Uses will only illustrated my pulse width). As described above, the pulse width modulation signal C _s is generated by the pulse width modulation signal generation unit 12 to always correspond to the input image signal S _s regardless of what gradation region the input image signal S _s belongs to. Thus, by providing the driver IC 20 side, the luminance of the LEDs in each pixel is adjusted.

However, this conventional method of controlling the LEDs using only the pulse width modulation signal has a limitation in color expression through fine adjustment of the luminance of the LEDs. That is, when controlling the luminance of the LEDs depending only on the pulse width modulation signal method, as can be seen from the gamma curve (γcurve) shown in Figure 29, generally, R, G, B input (x axis, pulse width The slope of the output luminance value (corresponding to the modulated signal) (y-axis) follows a gamma curve (γ) that is relatively very small in the low gradation region and relatively large in the high gradation region, particularly in the low gradation region. The increase in the output luminance value according to the increase of the R, B, and B inputs has a very small characteristic. Therefore, in order to make the increase amount of the output luminance value smaller, it is necessary to take more detailed R, G, and B input signals, but there are limitations only with the conventional pulse width modulation signals. It is impossible to implement 16 bits or more using only a conventional pulse width modulation signal.

In particular, in the low gradation region, although it is possible to discriminate even the minute difference with the human eye, there is a limit that cannot be expressed more finely as described above in controlling using only the conventional pulse width modulation signal. In expressing a moving picture, fine expression power in such a low gradation region is considered very important. In addition, when controlling only with a pulse width modulation signal, a flicker phenomenon occurs due to a low duty ratio in a low gradation region, causing a deterioration in image quality.

The problem to be solved by the present invention is to obtain the pixel data for each location at different locations in order to solve the problem that the viewer cannot watch the optimal uniform image by showing the difference in luminance for each viewing position of the LED display. Provided is a new LED display luminance correction method and system, after determining a star reference value, determining correction factors for each location for each of the pixels, and combining these correction factors at a predetermined ratio to apply to all pixels of the LED display. Is to do.

In addition, a problem to be solved by the present invention is a process for adjusting the maximum luminance values to the minimum value based on the extracted minimum value after extracting the minimum value among the maximum luminance values, which is a conventional method in the correction for improving the image quality of the LED display. In order to overcome the shortcomings that the overall image quality improvement or uniformity improvement of the display is insufficient due to the presence of the display, an improved method of correcting the low-gradation region or the middle region of the LEDs in the pixels can be achieved. It is to provide a method and system for correcting luminance of an LED display.

In addition, a problem to be solved by the present invention is to provide an LED display driver IC capable of improving expression in a low gradation region of LEDs arranged in a matrix in an LED display device and an LED display luminance control method using the same. .

In addition, a problem to be solved by the present invention is to provide an LED display driver IC capable of reducing flicker in a low gradation region and an LED display luminance control method using the same.

In addition, the problem to be solved by the present invention is an LED display driver IC capable of improving the image quality of an LED display device by improving expression power in a low gray level region and a high dynamic range (HDR) and an LED using the same. It is to provide a method for adjusting the display brightness.

According to an aspect of the present invention for solving the above problem, the first LED, the second LED and the third LED is a plurality of pixels formed by a single pixel array of the LED display luminance correction method, (a) the Obtaining pixel data for each location at different locations in front of the LED display; (b) determining a reference value for each location in each pixel data for each location obtained in step (a); (c) determining correction coefficients for each of the pixels based on a reference value for each position determined in step (b); And (d) combining the correction factors for each position determined in step (c) at a predetermined ratio and applying them to all pixels of the LED display.

In order to solve the above problem, according to an aspect of the present invention, at least the first LED, the second LED and the third LED, a plurality of pixels formed of one pixel, the luminance correction of the LED display arranged in the lateral and longitudinal directions The system includes: a pixel data unit that acquires pixel data for each position of the LED display at different positions including the right, center, and left sides of the front of the LED display; A reference value setting unit for determining a reference value for each location from the pixel data for each location obtained from the pixel data unit; A correction coefficient setting unit for determining a correction coefficient for each location for each of the plurality of pixels according to a reference value for each location acquired by the reference value setting unit; And a luminance correction unit that combines the correction factors for each position obtained by the correction factor setting unit at a predetermined ratio and applies them to a plurality of pixels.

According to another aspect of the present invention, a luminance correction system of an LED display in which a plurality of pixels in which at least a first LED, a second LED, and a third LED are formed as one pixel is arrayed is located at the left side of the front of the LED display. Luminance values of the first LED, the second LED and the third LED for each of the first reference value, the second reference value, and the third reference value by measuring the luminance values of the first LED, the second LED, and the third LED A first correction coefficient, a second correction coefficient and a third correction coefficient that form a ratio of values; Measure the luminance values of the first LED, the second LED, and the third LED in the center of the front of the LED display, and measure the luminance values of the fourth reference value, the fifth reference value, and the sixth reference value, respectively. A fourth correction coefficient, a fifth correction coefficient, and a sixth correction coefficient that form a ratio of the luminance values of the two LEDs and the third LED; And the first LED for each of the seventh reference value, the eighth reference value, and the ninth reference value by measuring luminance values of the first LED, the second LED, and the third LED on the right side of the front side of the LED display. And a seventh correction coefficient, an eighth correction coefficient, and a ninth correction coefficient forming a ratio of luminance values of the second LED and the third LED, and combining the first to eighth correction coefficients at the same ratio. The luminance values of the first LED, the second LED, and the third LED in the pixels of the LED display are corrected.

According to another aspect of the present invention, a luminance correction method for an LED display including a plurality of pixels arranged in a matrix is a maximum luminance value of a high gray level area of each of the LEDs in the pixels. Generating correction data including first correction data that is configured and second correction data that is composed of a maximum luminance value of a low gray level region of each of the LEDs in the pixels; and the first correction data. Generating first correction coefficients for maximum luminance values of the high gradation region in the first correction data, based on a first minimum value, which is a minimum value among the maximum luminance values of the high gradation region within, and the second correction data A second correction system for maximum luminance values of the low grayscale region in the second correction data, based on a second minimum value that is a minimum value among the maximum luminance values of the low grayscale region within And generating numbers and normalizing the luminance of each of the LEDs in the pixels based on the first correction coefficients and the second correction coefficients.

According to another aspect of the present invention, a luminance correction system for correcting a luminance of an LED display including a plurality of pixels arranged in a matrix includes: maximum luminance values of a high gradation region for each of the LEDs in the pixels And a light measurement unit for generating correction data by measuring the maximum luminance values of the low-grayscale region, and comparing the maximum luminance values of the high-grayscale region within the correction data, which is the minimum value among the maximum luminance values of the high-grayscale region. A minimum value extracting unit for extracting a first minimum value and comparing a maximum luminance value of the low gradation region in the correction data to extract a second minimum value, which is a minimum value among the maximum luminance values of the low gradation region, and the first value First correction coefficients are generated for each of the maximum luminance values of the high grayscale region in the correction data based on a minimum value, and the second maximum Based on a value, a correction coefficient generation unit that generates second correction coefficients for each of the maximum luminance values of the low grayscale region in the correction data, and based on the first correction coefficients and the second correction coefficients. And a normalizing unit that normalizes the luminance of each of the LEDs in the pixels.

According to another aspect of the present invention, an LED display driver IC for adjusting the luminance of LEDs in an LED display corresponding to an input image signal includes a control unit for determining a gray level of the input image signal, and the control unit In accordance with the control of the pulse width modulation signal generating unit for generating a pulse width modulation signal corresponding to the gradation of the input image signal, and the pulse amplitude for generating a pulse amplitude modulation (PAM) signal corresponding to the gradation of the input image signal A merge signal generator including a modulated signal generator and a pulse width modulated signal generated by the pulse width modulated signal generator and a pulse amplitude modulated signal generated by the pulse amplitude modulated signal generator to generate a merged signal. And the pulse amplitude modulation signal generator performs pulse amplitude modulation on the pulse width modulation signal to perform the merge signal. The generation, or subjected to the PWM signal generator the pulse width modulation on the pulse amplitude modulation signal is characterized in that the generating of the remaining signal.

According to another aspect of the present invention, a method of adjusting the luminance of LEDs in an LED display with an LED display driver IC corresponding to an input image signal includes: determining, by a control unit, a gray level of the input image signal; , Generating a pulse width modulation (PWM) signal corresponding to the gradation of the input image signal depending on the determination of the control unit, and pulse amplitude modulation corresponding to the gradation of the input image signal depending on the determination of the control unit ( PAM) generating a signal, merging the pulse width modulated signal and the pulse amplitude modulated signal to generate a merge signal, and adjusting the luminance of the LEDs with the merge signal.

The present invention obtains pixel data for each location at different locations, determines a reference value for each location, determines correction factors for each location for each pixel, and combines these correction factors at a predetermined ratio to combine pixels of the LED display. By providing a method and system for correcting brightness of a new LED display applied to all of them, the problem of showing a difference in brightness for each viewing position of a conventional LED display is solved, so that an optimal uniform image can be viewed by the viewer through the LED display device. It has the effect of making it possible.

In addition, the present invention is not limited to the region having the maximum luminance value of the LEDs in the pixels of the LED display, and an improved method of luminance correction method and system capable of performing luminance correction even for a region or a region having a low gradation. By providing, it has the effect of improving the overall image quality, uniformity, and expression of the LED display.

In addition, the present invention, in particular, compared to the characteristics of the low grayscale region, that is, compared to the middle grayscale region or the high grayscale region, since the users of the LED display tend to perceive the luminance difference between pixels more prominently, in the low grayscale region , The effect of reducing the luminance difference through correction is large.

In addition, the present invention provides an improved LED display driver IC and a method for adjusting the brightness of the LED display using the same, thereby improving the expression power in the low gradation region of the LED display device and flickering in the low gradation region. It can be reduced, and it has an effect of improving the image quality of the LED display device by improving expression power in a low gray level region and a high dynamic range (HDR).

1 is a view for explaining a process of acquiring pixel data for each location by arranging a camera (meter) at different locations P1, P2, and P3 for correction according to an embodiment of the present invention,

2 is a diagram illustrating an example of pixel data ML_pxd measured at a first position (left position, P1),

3 is a diagram illustrating an example of pixel data MC_pxd measured at a second position (central position, P2),

4 is a diagram illustrating an example of pixel data MR_pxd measured at a third position (right position, P3),

5 to 7 are views showing a specific example of the pixel data measured at the first position (left position, P1), FIG. 5 is data for the red LED R at the first position, and FIG. 6 is the first Data for the green LED (G) at position 1, and FIG. 7 is data for the blue LED (B) at position 1,

8 to 10 are views showing a specific example of the pixel data obtained at the second position (center position, P1), FIG. 8 is data for the red LED R at the second position, and FIG. 9 is the second Data for the green LED (G) at the 2 position, Figure 10 is data for the blue LED (B) at the second position,

11 to 13 are views showing a specific example of the pixel data obtained at the third position (right position, P3), FIG. 11 is data for the red LED R at the third position, and FIG. 12 is the first Data for the green LED (G) at position 3, and FIG. 13 is data for the blue LED (B) at position 3,

14 is a view showing an example of a table for applying the correction coefficients computed based on the reference values for each position to each of the LEDs of the pixels,

15 is a view showing final pixel data (F_pxd) in a state in which the correction coefficients of FIG. 14 are applied to the LEDs of each pixel,

16 is a view for explaining the luminance correction system 100 of the LED display according to an embodiment of the present invention,

17 is a block diagram illustrating a luminance correction method and a luminance correction system according to an embodiment of the present invention,

18 is a view for explaining a process of measuring the luminance of each LED of the pixels with the light measuring unit 120 in the luminance correction method and system according to an embodiment of the present invention,

19 is a view for explaining a conventional luminance correction method compared to the present invention,

20 is a view for explaining a process of detecting a first minimum value and a second minimum value from the correction data for each of the pixels of the LED display in the luminance correction method and system according to an embodiment of the present invention,

21 is a view for explaining a process of detecting a first minimum value, a second minimum value, and an intermediate value from correction data for each of the pixels of the LED display in the luminance correction method and system according to an embodiment of the present invention,

22 illustrates a process of detecting a first minimum value, a second minimum value, a third minimum value, and a fourth minimum value from the correction data for each of the pixels of the LED display in the luminance correction method and system according to an embodiment of the present invention As a drawing for the purpose, the third minimum value and the fourth minimum value are the minimum values of the maximum luminance values in each by dividing the grayscale region into the first grayscale region and the second grayscale region,

23 is a block diagram summarizing a luminance correction method according to an embodiment of the present invention,

FIG. 24 is a view for explaining a process of normalizing the entire region of the LEDs with the first correction coefficients and the second correction coefficients generated in FIG. 20,

FIG. 25 is a diagram for explaining a process of normalizing the entire region of the LEDs with the first correction coefficients, the second correction coefficients, and the third correction coefficients generated in FIG. 21,

26 is a block diagram of a drive IC 20 for driving LEDs in pixels arranged in a matrix on the display unit 10 in a general LED display device,

27 are examples of various pulse width modulation (PWM) signals,

28 is a block diagram for explaining a relationship between a general input image signal, a pulse width modulated signal generator and a driver IC,

29 is an example of a gamma curve (γcurve) of the output luminance for the R, G, and B input signals,

30 is a basic block diagram of an LED driver IC 100 according to the present invention,

31 is a block diagram of an LED driver IC according to an embodiment of the present invention,

32 is a view showing examples of the pulse width modulation signal (S _w ) and the pulse amplitude modulation signal (S _a ) in FIG. 31,

33 is a block diagram of an LED driver IC according to another embodiment of the present invention,

34 is a view showing examples of the pulse width modulation signal (S _w ) and the pulse amplitude modulation signal (S _a ) in FIG. 33,

35 is a block diagram of an LED driver IC according to another embodiment of the present invention,

36 is a view for explaining a process of generating a merge signal applied only when the input image signal is in a low gray level region in the embodiment of FIG. 35,

FIG. 37 is a view for explaining a process of generating a merge signal applied only when the input image signal is in a high gray level region in the embodiment of FIG. 35,

38 is a view for explaining a process of generating a merge signal applied when the input image signal is in a low grayscale region or a high grayscale region in the embodiment of FIG. 35;

39 is a gamma curve for showing the disadvantages of a conventional method of controlling luminance with only a pulse width modulated signal,

40 is a view showing the characteristics of the present invention using the merge signal of the pulse amplitude modulation signal and the pulse amplitude modulation signal,

41 is a view showing examples of a merge signal (a signal generated by merging of a pulse width modulated signal and a pulse width modulated signal) according to an embodiment of the present invention for gray scale.

Terms used in this specification are defined as follows.

ML_pxd, MC_pxd and MR_pxd are pixel data for each position, specifically, ML_pxd is pixel data measured at a first position (left position, P1), and LR (i, j), LG (i, j) included in ML_pxd ), LB (i, j) are pixel data measured at the first position, and LRij, LGij, and LBij are luminance values in the pixel data. And, MC_pxd is the pixel data measured at the second position (center position, P2), CR (i, j), CG (i, j), and CB (i, j) included in MC_pxd are pixel data, and CRij , CGij and LBij are luminance values in the pixel data measured at the second position. In addition, MR_pxd is pixel data measured at a third position (right position, P3), and RR (i, j), RG (i, j), and RB (i, j) included in MR_pxd are pixel data, and RRij , RGij and RBij are luminance values in the pixel data measured at the third position. Here, i is a natural number from 1 to m, j is a natural number from 1 to n.

More specifically, LR (i, j) is the first pixel data, LRij is the luminance value in the first pixel data, LG (i, j) is the second pixel data, and LGij is the luminance value in the second pixel data , LB (i, j) is the third pixel data, LBij is the luminance value in the third pixel data, CR (i, j) is the fourth pixel data, CRij is the luminance value in the fourth pixel data, and CG ( i, j) is the fifth pixel data, CGij is the luminance value in the fifth pixel data, CB (i, j) is the sixth pixel data, CBij is the luminance value in the sixth pixel data, and RR (i, j) Is the seventh pixel data, RRij is the luminance value in the seventh pixel data, RG (i, j) is the eighth pixel data, RGij is the luminance value in the eighth pixel data, and RB (i, j) is the ninth pixel data. It is pixel data and RBij is defined as the luminance value in the ninth pixel data. Looking at one pixel as reference, the first to ninth pixel data are defined for each of the pixels. That is, the first to ninth pixel data are all present in the pixel data for one pixel. For example, the pixel data of the first pixel, that is, the (1,1) pixel includes first pixel data LR (1,1), second pixel data LG (1,1), and third pixel data LB ( 1,1)), 4th pixel data (CR (1,1)), 5th pixel data (CG (1,1)), 6th pixel data (CB (1,1)), 7th pixel data ( RR (1,1)), eighth pixel data RG (1,1), and ninth pixel data BB (1,1). The same applies to the pixel data of (m, n) pixels.

In addition, ref_LR, ref_LG, ref_LB, ref_CR, ref_CG, ref_CB, ref_RR, ref_RG, ref_RB are reference values for each location, specifically, ref_LR is a first reference value, ref_LG is a second reference value, refLB is a third reference value, ref_CR is the fourth reference value, ref_CG is the fifth reference value, ref_CB is the sixth reference value, ref_RR is the seventh reference value, ref_RG is the eighth reference value, and ref_RB is the ninth reference value.

In addition, CC_LR, CC_LG, CC_LB, CC_CR, CC_CG, CC_CB, CC_RR, CC_RG, CC_RB are position-specific correction coefficients, specifically, CC_LR is a first correction coefficient, CC_LG is a second correction coefficient, and CC_LB is a third The correction factor, CC_CR is the fourth correction factor, CC_CG is the fifth correction factor, CC_CB is the sixth correction factor, CC_RR is the seventh correction factor, CC_RG is the eighth correction factor, and CC_RB is the ninth correction factor. to be.

1 is a view for explaining a process of acquiring pixel data for each location by arranging a camera (measurement device) at different locations P1, P2, and P3 for correction according to an embodiment of the present invention; Is a diagram showing an example of pixel data (ML_pxd) measured at a first position (left position, P1), and FIG. 3 is an example of pixel data (MC_pxd) measured at a second position (central position, P2) 4 is a diagram illustrating an example of pixel data MR_pxd measured at a third position (right position, P3).

1 to 4, the luminance correction method of the LED display of the present invention, first, pixel data per location (ML_pxd, MC_pxd) at different positions (P1, P2, P3) in front of the LED display 10 And MR_pxd). The process of acquiring the pixel data for each position (ML_pxd, MC_pxd, and MR_pxd), as shown, is a camera at the left position (P1), the center position (P2), and the right position (P3) with a certain distance from the LED display 10 After being photographed as, it is processed by the pixel data processing unit (not shown), and may be stored by location, pixel by pixel, and LED by pixel (see FIGS. 5 to 13 for each location, pixel, and LED within pixel). Separately stored examples).

Referring to FIG. 2, an example of pixel data ML_pxd measured at a first position, that is, a left position P1, is illustrated. The pixel data ML_pxd measured at the left position P1 includes first pixel data LR (i, j), second pixel data LG (i, j) and third pixel data LB (i, j) )). Since the LEDs in the pixels (the first to third LEDs emitting light of R, G, and B colors respectively) will emit each light having a specific light characteristic, they are measured by the camera at the left position P1. The obtained data will actually appear in various colors, but for convenience, the colors are not distinguished in the drawings.

The pixel data ML_pxd measured at the left position P1 includes all pixel data for the pixel located at (m, n) from the pixel located at (1,1). Here, (1,1), ..., (1, n), ..., (m, 1), ..., and (m, n) are the coordinates of the pixels in the LED display, from the top left It is numbered in a matrix in order from the bottom right.

The data for the light emitted by the LEDs in the first pixel, that is, the pixel of (1,1) is the first pixel data LR (1,1), the second pixel data LG (1,1), and 3 pixel data (LB (1, 1)). Similarly, data for light emitted by the LEDs in the pixels of (1, n) includes first pixel data LR (1, n), second pixel data LG (1, n), and third pixel data LB (1, n)), and data for light emitted by the LEDs in the pixel of (m, n) is the first pixel data (LR (m, n)) and the second pixel data (LG (m, n)) , And the third pixel data LB (m, n). Thus, the pixel data ML_pxd measured at the left position P1 is the first pixel data LR (m, n) for each pixel. , m and n are natural numbers of 1 or more), second pixel data (LG (m, n), m and n are natural numbers of 1 or more), and third pixel data (LB (m, n), m and n are 1 or more Natural water).

Referring to FIG. 3, an example of pixel data MC_pxd measured at a second position, that is, a central position P2 is illustrated. The pixel data MC_pxd measured at the central position P2 includes the fourth pixel data CR (i, j), the fifth pixel data CG (i, j), and the sixth pixel data CB (i, j) )). Since the LEDs in the pixels (the first to third LEDs emitting light of R, G, and B colors respectively) will emit each light having a specific light characteristic, they are measured by the camera at the central position P2. The acquired data will actually appear in various colors, but as in FIG. 2, for convenience, the colors are not distinguished in the drawings.

The pixel data (MC_pxd) measured at the central position (P2), as well as the pixel data (ML_pxd) measured at the previous left position (P1), is from the pixel located at (1,1) to the pixel located at (m, n). Contains all relevant pixel data.

The data for the light emitted by the LEDs in the pixel of the first pixel, namely (1,1), is the fourth pixel data CR (1,1), the fifth pixel data CG (1,1), and the 6 pixel data (CB (1,1)). Similarly, data for light emitted by the LEDs in the pixels of (1, n) includes fourth pixel data CR (1, n), fifth pixel data CG (1, n), and sixth pixel data CB (1, n)), and data for the light emitted by the LEDs in the pixel of (m, n) is the fourth pixel data (CR (m, n)) and the fifth pixel data (CG (m, n)) , And the sixth pixel data CB (m, n), Thus, the pixel data MC_pxd measured at the central position P2 is the fourth pixel data CR (m, n) for each pixel. , m and n are natural numbers of 1 or more), fifth pixel data (CG (m, n), m and n are natural numbers of 1 or more), and sixth pixel data (CB (m, n), m and n is 1 or more Natural water).

Referring to FIG. 4, an example of pixel data MR_pxd measured at a third position, that is, a right position P3 is illustrated. The pixel data MR_pxd measured at the right position P3 includes seventh pixel data RR (i, j), eighth pixel data RG (i, j) and ninth pixel data RB (i, j )). Since the LEDs in the pixels (the first to third LEDs emitting light of R, G, and B colors respectively) will emit each light having a specific light characteristic, they are measured by the camera at the right position P3. The acquired data will actually appear in various colors, but as in FIGS. 2 and 3 described above, for convenience, the colors are not distinguished in the drawings.

The pixel data (MR_pxd) measured at the right position (P3), as well as the pixel data (ML_pxd or MC_pxd) measured at the previous left position (P1) or the center position (P2), starts from the pixel located at (1,1) ( m, n), and includes pixel data for each pixel.

The data for the light emitted by the LEDs in the first pixel, that is, the pixel of (1,1) is the seventh pixel data (RR (1,1)), the eighth pixel data (RG (1,1)), and 9 pixel data (RB (1,1)). Similarly, data for light emitted by the LEDs in the pixel of (1, n) includes seventh pixel data RR (1, n), eighth pixel data RG (1, n), and ninth pixel data RB (1, n)), and data for the light emitted by the LEDs in the pixel of (m, n) is the seventh pixel data (RR (m, n)) and the eighth pixel data (RG (m, n)) , And ninth pixel data RB (m, n), as described above, the pixel data MR_pxd measured at the right position P3 is the seventh pixel data RR (m, n) for each pixel. , m and n are natural numbers of 1 or more), 8th pixel data (RG (m, n), m and n are natural numbers of 1 or more), and 9th pixel data (RB (m, n), m and n is 1 or more Natural water).

5 to 13 are specific examples of pixel data measured at the first position (left position, P1), the second position (center position, P2), and the third position (right position, P3), and reference values for each position therefrom These are drawings for explaining the process of generating the correction coefficients.

First, FIGS. 5 to 7 are views showing a specific example (luminance value for each LED in each pixel) of the pixel data measured at the first position (left position, P1), and FIG. 5 is at the first position (P1) Is data (luminance value) for the red LED R of FIG. 6 is data (luminance value) for the green LED G at the first position P1, and FIG. 7 is at the first position P1 This is the data (luminance value) for the blue LED (B).

Referring to FIG. 5, the luminance value in the pixel data for the first LED (red LED) in the first pixel, that is, the (1,1) pixel is LR11, and the first LED (red LED) in the (1, n) pixel The luminance value in the pixel data for is LR1n, and the luminance value in the pixel data for the first LED (red LED) in (m, n) pixels is LRmn. CC_LR is a first correction coefficient, and is determined depending on a reference value for each position (here, a first reference value). For example, as shown in FIG. 5, among the luminance values in the pixel data for the first LED (red LED), if the luminance value of the (m, 4) pixel is the lowest, the first reference value is LRm4. Therefore, the first correction coefficient CC_LR is a value obtained by dividing the first reference value LRm4 by the luminance value for each pixel. That is, CC_LR = LRm4 / LRij (where i = 1, 2, ..., m, and j = 1, 2, ..., n).

For example, the first correction coefficient (CC_LR) of the (1,1) pixel is LRm4 / LR11, the first correction coefficient (CC_LR) of the (1,2) pixel is LRm4 / LR12, and the (1, n) pixel The first correction coefficient (CC_LR) of is LRm4 / LR1n, and the first correction coefficient (CC_LR) of the (m, n) pixel is LRm4 / LRmn.

In this way, among the pixel data measured at the first position (left position, P1), the first reference value (ref_LR) is determined from the pixel data related to the first LED, that is, the luminance values of the first LEDs in the first pixel data. A first correction coefficient (CC_LR) for the first LED in each pixel is determined by the first reference value.

Referring to FIG. 6, the luminance value in the pixel data for the second LED (green LED) in the first pixel, that is, the (1,1) pixel is LG11, and the second LED (green LED) in the (1, n) pixel The luminance value in the pixel data for is LG1n, and the luminance value in the pixel data for the second LED (green LED) in (m, n) pixels is LGmn. CC_LG is a second correction coefficient, and is determined depending on a reference value for each position (here, a second reference value). For example, as illustrated in FIG. 6, among the luminance values in the pixel data for the second LED (green LED), if the luminance value of the (m-1,3) pixel is the lowest, the second reference value is LGm- It becomes 13. Therefore, the second correction coefficient CC_LG is a value obtained by dividing the second reference value LGm-13 by the luminance value for each pixel. That is, CC_LG = LGm-13 / LGij (where i = 1, 2, ..., m, and j = 1, 2, ..., n).

For example, the second correction coefficient (CC_LG) of the (1,1) pixel is LGm-13 / LG11, and the second correction coefficient (CC_LG) of the (1,2) pixel is LGm-13 / LG12, (1 , n) The second correction coefficient (CC_LG) of the pixel is LGm-13 / LG1n, and the second correction coefficient (CC_LG) of the (m, n) pixel is LGm-13 / LGmn.

Thus, the second reference value ref_LG is determined from the pixel data related to the second LED among the pixel data measured at the first position (left position, P1), that is, the luminance values of the second LEDs in the second pixel data. The second correction value CC_LG for the second LED in each pixel is determined by the second reference value.

Referring to FIG. 7, the luminance value in the pixel data for the third LED (blue LED) in the first pixel, that is, the (1,1) pixel is LB11, and the third LED (blue LED) in the (1, n) pixel The luminance value in the pixel data for is LB1n, and the luminance value in the pixel data for the third LED (blue LED) in (m, n) pixels is LBmn. CC_LB is a third correction coefficient, and is determined depending on a reference value for each position (here, a third reference value). For example, as illustrated in FIG. 7, among the luminance values in the pixel data for the third LED (blue LED), if the luminance value of the (m-2,1) pixel is the lowest, the third reference value is LBm- 21. Therefore, the third correction coefficient CC_LB is a value obtained by dividing the third reference value LBm-21 by the luminance value for each pixel. That is, CC_LB = LBm-21 / LBij (where i = 1, 2, ..., m, and j = 1, 2, ..., n).

For example, the third correction factor (CC_LB) of the (1,1) pixel is LBm-21 / LB11, and the third correction factor (CC_LB) of the (1,2) pixel is LBm-21 / LB12, and (1 , n) The third correction coefficient (CC_LB) of the pixel is LBm-21 / LB1n, and the third correction coefficient (CC_LB) of the (m, n) pixel is LBm-21 / LBmn.

As described above, from the pixel data of the third LED among the pixel data measured at the first position (left position, P1), that is, the luminance value for each of the third LEDs in the third pixel data, the third reference value ref_LB is determined, The third correction value CC_LB for the third LED in each pixel is determined by the third reference value.

8 to 10 are views showing a specific example of the pixel data obtained at the second position (central position, P2), FIG. 8 is data for the red LED R at the second position, and FIG. 9 is the second Data for the green LED (G) at the 2 position, and FIG. 10 is data for the blue LED (B) at the second position.

Referring to FIG. 8, the luminance value in the pixel data for the first LED (red LED) in the first pixel, that is, the (1,1) pixel is CR11, and the first LED (red LED) in the (1, n) pixel The luminance value in the pixel data for is CR1n, and the luminance value in the pixel data for the first LED (red LED) in (m, n) pixels is CRmn. CC_CR is a fourth correction coefficient, and is determined depending on a reference value for each position (here, a fourth reference value). For example, as illustrated in FIG. 8, among the luminance values in the pixel data for the first LED (blue LED), if the luminance value of the (m-1, n-1) pixel is the lowest, the fourth reference value is It becomes CRm-1n-1. Therefore, the fourth correction coefficient CC_CR is a value obtained by dividing the fourth reference value CRm-1n-1 by the luminance value for each pixel. That is, CC_CR = CRm-1n-1 / CRij (where i = 1, 2, ..., m, and j = 1, 2, ..., n).

For example, the fourth correction coefficient (CC_CR) of the (1,1) pixel is CRm-1n-1 / CR11, and the fourth correction coefficient (CC_CR) of the (1,2) pixel is CRm-1n-1 / CR12 Is, the fourth correction coefficient (CC_CR) of the (1, n) pixel is CRm-1n-1 / CR1n, and the fourth correction coefficient (CC_CR) of the (m, n) pixel is CRm-1n-1 / CRmn .

As described above, in the pixel data related to the first LED (red LED) among the pixel data measured at the second position (center position, P2), that is, the luminance value for each of the first LEDs in the fourth pixel data, the fourth reference value (ref_CR ) Is determined, and a fourth correction coefficient (CC_CR) for the first LED (red LED) in each pixel is determined by the fourth reference value.

Referring to FIG. 9, the luminance value in the pixel data for the second LED (green LED) in the first pixel, that is, the (1,1) pixel is CG11, and the second LED (green LED) in the (1, n) pixel The luminance value in the pixel data for is CG1n, and the luminance value in the pixel data for the first LED (green LED) in (m, n) pixels is CGmn. CC_CG is a fifth correction coefficient, and is determined depending on a reference value for each position (here, a fifth reference value). For example, as shown in FIG. 9, among the luminance values in the pixel data for the second LED (green LED), if the luminance value of the (1,4) pixel is the lowest, the fifth reference value is CG14. Therefore, the fifth correction coefficient CC_CG is a value obtained by dividing the fifth reference value CG14 by the luminance value for each pixel. That is, CC_CG = CG14 / CGij (where i = 1, 2, ..., m, and j = 1, 2, ..., n).

For example, the fifth correction coefficient (CC_CG) of (1,1) pixels is CG14 / CG11, the fifth correction coefficient (CC_CG) of (1,2) pixels is CG14 / CG12, and (1, n) pixels The fifth correction coefficient of CC_CG is CG14 / CG1n, and the fifth correction coefficient (CC_CG) of (m, n) pixels is CG14 / CGmn.

As described above, in the pixel data related to the second LED (green LED) among the pixel data measured at the second position (center position, P2), that is, the luminance value for each of the second LEDs in the fifth pixel data, the fifth reference value (ref_CG ) And a fifth correction coefficient (CC_CG) for the second LED (green LED) in each pixel is determined by the fifth reference value.

Referring to FIG. 10, the luminance value in the pixel data for the third LED (blue LED) in the first pixel, (1,1) pixels is CB11, and the third LED (blue LED) in (1, n) pixels The luminance value in the pixel data for is CB1n, and the luminance value in the pixel data for the third LED (blue LED) in (m, n) pixels is CBmn. CC_CB is a sixth correction coefficient and is determined depending on a reference value for each position (here, a sixth reference value). For example, as illustrated in FIG. 10, among the luminance values in the pixel data for the third LED (blue LED), if the luminance value of the (2,4) pixel is the lowest, the sixth reference value is CB24. Accordingly, the sixth correction coefficient CC_CB is a value obtained by dividing the sixth reference value CB24 by the luminance value for each pixel. That is, CC_CB = CB24 / CBij (where i = 1, 2, ..., m, and j = 1, 2, ..., n).

For example, the sixth correction coefficient (CC_CB) of the (1,1) pixel is CB24 / CB11, the sixth correction coefficient (CC_CB) of the (1,2) pixel is CB24 / CB12, and the (1, n) pixel The 6th correction coefficient (CC_CB) of is CB24 / CB1n, and the 6th correction coefficient (CC_CB) of (m, n) pixels is CB24 / CBmn.

As described above, in the pixel data related to the third LED (blue LED) among the pixel data measured at the second position (center position, P2), that is, the luminance value for each of the third LEDs in the sixth pixel data, the sixth reference value (ref_CB ) And a sixth correction coefficient (CC_CB) for a third LED (blue LED) in each pixel is determined by the sixth reference value.

11 to 13 are views showing a specific example of the pixel data obtained at the third position (right position, P3), FIG. 11 is data for the red LED R at the third position, and FIG. 12 is the first Data for the green LED (G) at the 3 position, and FIG. 13 is data for the blue LED (B) at the 3rd position.

Referring to FIG. 11, the luminance value in the pixel data for the first LED (red LED) in the first pixel, that is, the (1,1) pixel is RR11, and the first LED (red LED) in the (1, n) pixel The luminance value in the pixel data for is RR1n, and the luminance value in the pixel data for the first LED (red LED) at (m, n) pixels is RRmn. CC_RR is a seventh correction coefficient, and is determined depending on a reference value for each position (here, a seventh reference value (ref_RR)). For example, as illustrated in FIG. 11, if the luminance value of the (m-1,3) pixel among the luminance values in the pixel data for the first LED (red LED) is the lowest, the seventh reference value is RRm-13. Becomes Therefore, the seventh correction coefficient CC_RR is a value obtained by dividing the seventh reference value RRm-13 by the luminance value for each pixel. That is, CC_RR = RRm-13 / RRij (where i = 1, 2, ..., m, and j = 1, 2, ..., n).

For example, the seventh correction coefficient (CC_RR) of the (1,1) pixel is RRm-13 / RR11, and the seventh correction coefficient (CC_RR) of the (1,2) pixel is RRm-13 / RR12, and (1 , n) The seventh correction coefficient (CC_RR) of the pixel is RRm-13 / RR1n, and the seventh correction coefficient (CC_RR) of the (m, n) pixel is RRm-13 / RRmn.

As described above, in the pixel data related to the first LED (red LED) among the pixel data measured at the third position (right position, P3), that is, the luminance value for each of the first LEDs in the seventh pixel data, the seventh reference value (ref_RR ) Is determined and a seventh correction coefficient (CC_RR) for the first LED (red LED) in each pixel is determined by the determined seventh reference value.

Referring to FIG. 12, the luminance value in the pixel data for the second LED (green LED) in the first pixel, that is, the (1,1) pixel is RG11, and the second LED in the (1, n) pixel (green LED) The luminance value in the pixel data for is RG1n, and the luminance value in the pixel data for the second LED (green LED) in the (m, n) pixel is RGmn. CC_RG is an eighth correction coefficient, and is determined depending on the reference value for each position (here, the eighth reference value ref_RG). For example, as illustrated in FIG. 12, if the luminance value of the (2, n-1) pixel among the luminance values in the pixel data for the second LED (green LED) is the lowest, the eighth reference value is RG2n-1. Becomes Accordingly, the eighth correction coefficient CC_RG is a value obtained by dividing the eighth reference value RG2n-1 by the luminance value for each pixel. That is, CC_RG = RG2n-1 / RGij (where i = 1, 2, ..., m, and j = 1, 2, ..., n).

For example, the eighth correction coefficient (CC_RG) of the (1,1) pixel is RG2n-1 / RG11, and the eighth correction coefficient (CC_RG) of the (1,2) pixel is RG2n-1 / RG12, (1 , n) The eighth correction coefficient (CC_RG) of the pixel is RG2n-1 / RG1n, and the eighth correction coefficient (CC_RG) of the (m, n) pixel is RG2n-1 / RGmn.

As described above, in the pixel data related to the second LED (green LED) among the pixel data measured at the third position (right position, P3), that is, the luminance value for each of the second LEDs in the eighth pixel data, the eighth reference value ref_RG ) Is determined and the eighth correction coefficient CC_RG for the second LED (green LED) in each pixel is determined by the determined eighth reference value.

Referring to FIG. 13, the luminance value in the pixel data for the third LED (blue LED) in the first pixel, that is, the (1,1) pixel is RB11, and the third LED (blue LED) in the (1, n) pixel The luminance value in the pixel data for is RB1n, and the luminance value in the pixel data for the third LED (blue LED) in (m, n) pixels is RBmn. CC_RB is the ninth correction coefficient, and is determined depending on the reference value for each position (here, the ninth reference value (ref_RB)). For example, as illustrated in FIG. 13, if the luminance value of the (1,1) pixel among the luminance values in the pixel data for the third LED (blue LED) is the lowest, the ninth reference value is RB11. Therefore, the ninth correction coefficient CC_RB is a value obtained by dividing the ninth reference value RB11 by the luminance value for each pixel. That is, CC_RB = RB11 / RBij (where i = 1, 2, ..., m, and j = 1, 2, ..., n).

For example, the ninth correction coefficient (CC_RB) of (1,1) pixels is RB11 / RB11, the ninth correction coefficient (CC_RB) of (1,2) pixels is RB11 / RB12, and (1, n) pixels The ninth correction coefficient (CC_RB) of is RB11 / RB1n, and the ninth correction coefficient (CC_RB) of (m, n) pixels is RB11 / RBmn.

As described above, in the pixel data related to the third LED (blue LED) among the pixel data measured at the third position (right position, P3), that is, the luminance value for each of the third LEDs in the ninth pixel data, the ninth reference value (ref_RB ) Is determined and the ninth correction coefficient CC_RB for the third LED (blue LED) in each pixel is determined by the determined ninth reference value.

As described above, the luminance correction method of the LED display of the present invention acquires pixel data for each position at different positions (P1, P2, P3: FIG. 1) in front of the LED display, and thus obtained pixel data for each position After determining the reference value for each location, the correction coefficients for each location are determined based on the determined location-specific reference value for each of the pixels (specifically, each of the red LED, green LED, and blue LED of each pixel). As described above with reference to the drawings, the correction coefficients for each position are expressed as a ratio of luminance values of LEDs in each pixel to the determined reference value for each position.

FIG. 14 shows the correction coefficients (CC_LR, CC_LG, CC_LB, CC_CR, CC_CG, CC_CB, CC_RR, CC_RG, CC_RB) computed based on the location-specific reference values (the first to ninth reference values). (First LED (R), second LED (G), and a third LED (B)) is a diagram showing an example of a table for applying to each, Figure 15 is the LED of each of the pixels of the correction coefficients of Figure 14 It is a figure showing the final pixel data (F_pxd) in a state applied to the fields.

Referring to FIG. 14, pixels located in a first column (in the (m, n) notation, m part is a row and n part is defined as a column), that is, a red LED (R) in the (1,1) pixel, Green LED (G), Blue LED (B), Red LED in (2,1) pixels (R), Green LED (G), Blue LED (B), ..., (m, 1) Red LED in pixels For each of the (R), green LED (G), and blue LED (B), the first correction factor (CC_LR) is applied to the red LED (R), and the second correction factor (CC_LG) is applied to the green LED (G). ) Was applied, and a third correction coefficient (CC_LB) was applied to the blue LED (B). Here, the first correction coefficient CC_LR, the second correction coefficient CC_LG, and the third correction coefficient CC_LB are all coefficients computed based on the pixel data measured at the first position (left position, P1).

Then, the pixels located in the second column, that is, the red LED (R), the green LED (G), the blue LED (B) in the (1,2) pixel, the red LED (R) in the (2,2) pixel, green LED (G), Blue LED (B), ..., (m, 2) For each red LED (R), green LED (G), blue LED (B) in the pixel, for red LED (R) The fourth correction factor (CC_CR) was applied, the fifth correction factor (CC_CG) was applied to the green LED (G), and the sixth correction factor (CC_CB) was applied to the blue LED (B). Here, the fourth correction coefficient CC_CR, the fifth correction coefficient CC_CG, and the sixth correction coefficient CC_CB are all coefficients computed based on the pixel data measured at the second position (central position, P2).

In addition, the pixels located in the third column, that is, the red LED (R) in the (1,3) pixel, the green LED (G), the blue LED (B), and the red LED (R) in the (2,3) pixel, green LED (G), Blue LED (B), ..., (m, 3) For each red LED (R), green LED (G), blue LED (B) in the pixel, for red LED (R) The seventh correction factor (CC_RR) was applied, the eighth correction factor (CC_RG) was applied to the green LED (G), and the ninth correction factor (CC_RB) was applied to the blue LED (B). Here, the seventh correction coefficient CC_RR, the eighth correction coefficient CC_RG and the ninth correction coefficient CC_RB are all coefficients computed based on the pixel data measured at the third position (right position, P3).

Also, the first correction coefficient CC_LR, the second correction coefficient CC_LG, and the third correction coefficient CC_LB are applied to the pixels located in the fourth column, and the pixels located in the fifth column are the same as the first column. Like the second column, the fourth correction coefficient (CC_CR), the fifth correction coefficient (CC_CG), and the sixth correction coefficient (CC_CB) are applied, and for the pixels located in the sixth column, the seventh correction coefficient (CC_RR), like the third column, The eighth correction factor (CC_RG) and the ninth correction factor (CC_RB) were applied. By repeatedly applying as described above, it is possible to apply such that the ratio of the correction coefficients for each position to the total number of pixels is equal to 1: 1: 1. That is, the number of correction coefficients based on the pixel data measured at the first position P1 is called N (LR, LG, LB), and the number of correction coefficients based on the pixel data measured at the second position P2 is N When (CR, CG, CB) is called and the number of correction coefficients based on the pixel data measured at the third position P3 is N (RR, RG, RB), for all the LED displays, N ( LR, LG, LB) = N (CR, CG, CB) = N (RR, RG, RB).

The final pixel data F_pxd may be expressed as shown in the example shown in FIG. 15. That is, since the first correction coefficient CC_LR in FIG. 14 was previously applied to the red LED R of the (1,1) pixel, the final pixel data F_pxd after correction may be LR11 * CC_LR, and green Since the second correction coefficient CC_LG in FIG. 14 was previously applied to the LED G, the final pixel data F_pxd after the correction may be LG11 * CC_LG, and the blue LED B may be previously described in FIG. 14. Since the third correction coefficient CC_LB is applied, the final pixel data F_pxd_ after correction may be LB11 * CC_LB. Similarly, since the seventh correction coefficient (CC_RR) in FIG. 14 was previously applied to the red LED R of the (m, n) pixel, the final pixel data (F_pxd) after correction may be RRmn * CC_RR, and green Since the eighth correction coefficient CC_RG in FIG. 14 was previously applied to the LED G, the final pixel data F_pxd after correction may be RGmn * CC_RG, and the blue LED B may be previously described in FIG. 14. Since the ninth correction coefficient CC_RB is applied, the final pixel data F_pxd_ after correction may be RBmn * CC_RB.

As described above, the present invention measures luminance using cameras located at each of the left position, the center position, and the right position, computes a correction coefficient by setting a reference value, and adjusts the luminance value by applying the same ratio to all pixels of the display. By doing so, it solves the problem of showing the difference in luminance for each viewing position of the conventional LED display, and has the effect of allowing the viewer to view the optimal uniform image through the LED display device.

In the above description, pixel data is obtained by measuring with a camera at three locations, but pixel data measured at four or more locations may be used.

16 is a view for explaining the luminance correction system 100 of the LED display 10 according to an embodiment of the present invention.

If the luminance correction system 100 of the LED display 10 according to an embodiment of the present invention is described with reference to FIG. 16, at least a first LED (see LR in FIG. 2) and a second LED (see LG in FIG. 2) ) And the third LED (refer to LB in FIG. 2), the luminance correction system 100 of the LED display 10 of the present invention, in which a plurality of pixels are formed in a horizontal direction and a vertical direction, is an LED display (10) Pixel data unit for obtaining pixel data (ML_pxd, MC_pxd, MR_pxd) for each position of the LED display 10 at different positions including the front right (P3), middle (P2), and left (P1) (110), the reference value setting unit 120 for determining the reference value for each location from the pixel data for each location (ML_pxd, MC_pxd, MR_pxd) acquired by the pixel data unit 110, obtained from the reference value setting unit 120 Recall the correction factor for each location according to the reference value for each location The correction coefficient setting unit 130 for determining for each of several pixels, and the correction coefficients for each position obtained by the correction coefficient setting unit 130 are combined at a certain ratio (F_pxd in the drawing), so that all of the plurality of pixels are It includes a luminance correction unit 140 applied to. For the pixel data for each location, the reference value for each location, and the correction coefficients for each location, the contents of the luminance correction method described above may be applied as it is.

Also, referring to FIGS. 2 to 16 together, according to an embodiment of the present invention, at least a first LED (eg, LR in FIG. 2), a second LED (eg, LG in FIG. 2) and a third LED ( For example, the luminance correction system of the LED display 10 in which a plurality of pixels in which LB of FIG. 2 is formed as one pixel is arrayed is the first LED at the left P1 in front of the LED display 10, The ratio of the luminance values of the first LED, the second LED and the third LED to each of the first reference value, the second reference value, and the third reference value by measuring the luminance values of the second LED and the third LED ( ratio, the first correction coefficient CC_LR, the second correction coefficient CC_LG, and the third correction coefficient CC_LB, and the first LED in the center P2 of the front of the LED display 10, the By measuring the luminance values of the second LED and the third LED, each of the fourth reference value and the fifth group The fourth correction coefficient (CC_CR), the fifth correction coefficient (CC_CG) and the sixth, which form a ratio of the luminance values of the first LED, the second LED, and the third LED to the value (CC_CG) and the sixth reference value. Correction coefficient (CC_CB), and the luminance values of the first LED, the second LED, and the third LED on the right (P3) of the front of the LED display 10 are measured to determine the seventh reference value and the Seventh correction coefficient (CC_RR), eighth correction coefficient (CC_RG) and ninth correction coefficient forming ratios of luminance values of the first LED, the second LED and the third LED with respect to the 8 reference values and the ninth reference values (CC_RB) and combining the first to ninth correction coefficients at the same ratio to correct luminance values of the first LED, the second LED, and the third LED in the pixels of the LED display. .

Reference numerals of FIGS. 1 to 16 described above are as follows.

10: LED display, P1: first position (left position), P2: second position (center position), P3: third position (right position), 110: pixel data unit, 120: reference value setting unit, 130: correction Coefficient setting unit, 140: luminance correction unit.

Hereinafter, a luminance correction method and a luminance correction system of the present invention will be described with reference to FIGS. 17 to 25. Note that reference numerals in FIGS. 17 to 25 are limited to FIGS. 17 to 25 only. That is, the reference numerals indicated in FIGS. 1 to 16 described above are limited to FIGS. 1 to 16, and the reference numerals in FIGS. 17 to 25 described below are limited to FIGS. 17 to 25. .

The gray level of the image data may be divided into a low gray level area, a low gray level area, a mid gray level area, and a high gray level area, in order from a low area. The high gradation region is generally an area within 80% of the maximum luminance value, the low gradation region is the region within 30% of the maximum luminance value of the high gradation region, and the other regions are defined as the middle gradation region.

17 is a view for explaining a luminance correction system according to an embodiment of the present invention and a luminance correction method through the same, and FIG. 18 is a luminance correction system according to an embodiment of the present invention, to the light measurement unit 110 It is a diagram for explaining a method of measuring the luminance of the LEDs of each pixel. In FIG. 18, the number of pixels (px) of the LED display is m * n, and each of the pixels (px) includes a red LED (R), a green LED (G), and a blue LED (B) for full-color implementation. do.

17 and 18, according to an embodiment of the present invention, a luminance correction system 100 for correcting luminance of a display including a plurality of pixels arranged in a matrix includes: a light measurement unit 110, It includes a minimum value extraction unit 120, a correction coefficient generation unit 130 and a normalization unit 140.

The light measurement unit 110 is a component for measuring the luminance of the pixels of the LED display 1, and may be, for example, a camera or other light measurement equipment. In the light measuring unit 110, the process of measuring the luminance of the pixels (px) of the LED display 1 is as follows.

First, when all the pixels of the LED display 1 are lit at one time, to reduce the optical interference that may occur between adjacent pixels to increase the accuracy of the correction, for example, by grouping to include 9, 16, etc. pixels , By lighting only one pixel in a group at a time, it can be measured by the light measuring unit 110 in the absence of light interference from adjacent pixels. Therefore, when the number of pixels included in one group is 9, as shown in black in FIG. 18, the pixels that are lit are turned on by skipping two pixels in the row direction and two pixels in the column direction. The light is skipped and measured by the light measurement unit 110. The three LEDs in one pixel, that is, the red LED (R), the green LED (G), and the blue LED (B), respectively, are lit in this way. That is, in the row direction, the red LED (R) in the pixel px11, the red LED (R) in the pixel px14, and the like, the red LED (R) in the pixel px11 in the column direction, and the red LED (R) in the pixel px41, The red LEDs (R) and the like in px44 light up at the same time to measure the luminance with the light measuring unit 110, and when the measurement is finished, repeat for the red LEDs in the next pixels. The next lit pixels may be, for example, px12, px15, px18, ..., px42, px45, ..., and the like.

After the pixels (px) (specifically, LEDs in the pixels) are turned on, a light measuring unit is applied to the lit pixels by applying a current that causes the lit pixels to have maximum luminance values in a high gradation region. Measured by (110), and by applying a current to have a maximum luminance value in the low gradation region, the lighted pixels are measured by the light measurement unit 110. Through the above process, the light measurement unit 110 generates correction data including the maximum luminance value in the high gradation region and the maximum luminance value in the low gradation region for each of the pixels (px). The minimum value extraction unit 120 compares the maximum luminance values in the high gradation region within the correction data measured / generated by the light measurement unit 110 and extracts the first minimum value, which is the minimum value among the maximum luminance values. In addition, the minimum value extracting unit 120 compares the maximum luminance values in the low gradation region within the correction data measured / generated by the light measurement unit 110, and is the minimum value among the maximum luminance values in the low gradation region. The second minimum value is extracted.

The correction coefficient generation unit 130 generates first correction coefficients for each of the maximum luminance values in the high grayscale region in the correction data based on the first minimum value extracted by the minimum value extraction unit 120, and the Second correction coefficients are generated for each of the maximum luminance values in the low gradation region in the correction data based on a second minimum value.

Based on the first correction coefficients and the second correction coefficients generated by the correction coefficient generator 130, normalization is performed on the entire luminance region of the corresponding LEDs. For example, normalization is performed on the entire luminance region of the red LED R in px11 based on the first and second correction coefficients for the red LED R in px11, and for the red LED R in px12. Normalization is performed on the entire luminance region of the red LED R in px12 based on the first correction coefficient and the second correction coefficient. In this way, for each of the LEDs in all pixels, normalization is performed for the entire luminance region of each of the LEDs based on the respective first correction coefficient and the second correction coefficient. By performing the normalization as described above, by reducing the width of the luminance change according to the change in the supply current, it is possible to provide a smoother luminance transition between each pixel.

In performing normalization, in the entire luminance region of each LED, a region to which the first correction factor is applied and a region to which the second correction factor is applied can be divided. For example, in the entire luminance area of each of the LEDs, an area to which a first correction coefficient corresponding to each of the LEDs is applied, that is, an area covered by the first correction coefficient is covered by the top 50% of the total luminance area and a second correction coefficient. Correction can be performed by setting the region to be the lower 50% of the entire luminance region.

Furthermore, the light measurement unit 110 may further measure the maximum luminance value of the middle grayscale region, which is an intermediate region of the high grayscale region and the low grayscale region of each of the LEDs in the pixel (px). Accordingly, the maximum luminance value of the high grayscale region, the maximum luminance value of the low grayscale region, and the maximum luminance value of the grayscale region may be included in the correction data. Then, when the correction data is generated to further include the maximum luminance value of the grayscale region, the minimum value extracting unit 120 further extracts a third minimum value that is the minimum value among the maximum luminance values of the grayscale region within the correction data. In addition, the correction coefficient generation unit 130 may further generate third correction coefficients for each of the maximum luminance values of the grayscale region in the correction data based on the third minimum value.

Further, when the third correction coefficient is further generated, in normalizing, in the entire luminance region of each LED, the region to which the first correction factor is applied, the region to which the second correction factor is applied, and the third correction factor are set. The area to be applied can be divided. For example, in the entire luminance area of each of the LEDs, an area to which the first correction coefficient corresponding to each of the LEDs is applied, that is, an area covered by the first correction coefficient is covered by the top 30% of the total luminance area and the second correction coefficient. The correction may be performed by applying the region to the lower 30% of the entire luminance region and the region covered by the third correction coefficient to the remaining region. The areas covered by the first correction coefficient, the second correction coefficient, and the third correction coefficient for the entire luminance area may be changed at different ratios.

Furthermore, the light measurement unit 110 may generate a plurality of intermediate luminance values for each of the LEDs of the pixels to generate correction data including them (see FIG. 22).

Normalization in the present specification, as shown in Figure 17, the light measurement unit 110, the minimum value extraction unit 120, by a series of processes by the correction coefficient generation unit 130 to each of the LEDs When generating the first correction coefficient, the second correction coefficient, and the third correction coefficient for the grayscale region, the third correction coefficient is used to apply to the entire luminance region of each of the LEDs. . This will be described in more detail with reference to FIGS. 24 and 25 later.

In this way, the first correction coefficients, the second correction coefficients, and the third correction coefficients for each of the LEDs generated from the correction data are provided to the control unit 10, and the control unit 10 provides these first correction coefficients, By adjusting the normalization (Normalization) for each of the LEDs in the pixels using the second correction coefficients and the third correction coefficients, the brightness level of the LEDs in the pixels is adjusted. Through this process, the LED By improving the color expression power, it is possible to expect an overall image quality improvement and uniformity improvement effect.

19 is a view for explaining a conventional luminance correction method compared to the present invention, and FIG. 20 is a first from the correction data for each pixel of the LED display in the luminance correction method and system according to an embodiment of the present invention A diagram for explaining a process of detecting a minimum value and a second minimum value. 17 to 20, a description will be given of a luminance correction method according to the present invention.

According to the present invention, a luminance correction method for an LED display including a plurality of pixels arranged in a matrix consists of a maximum luminance value of each of the high gradation regions of the LEDs R, G, and B in the pixels px. Generating correction data including first correction data and second correction data composed of maximum luminance values of the low grayscale regions of the LEDs R, G, and B in the pixels px, the first Generating first correction coefficients for maximum luminance values of the high gradation region in the first correction data based on a first minimum value that is a minimum value among the maximum luminance values of the high gradation region in the correction data; and And generating second correction coefficients for minimum luminance values in the second correction data, based on a second minimum value, which is a minimum value among the maximum luminance values of the low grayscale region in the second correction data.

The conventional luminance correction method shown in FIG. 19 measures maximum luminance values in the high gradation regions for LEDs in each of the pixels by using light measuring equipment such as a camera, and maximum luminance in these high gradation regions After comparing the values and extracting the minimum value, the luminance levels of all the LEDs are corrected by normalizing the brightness level of all the LEDs to the entire luminance area based on the minimum value. However, as described above, the conventional luminance correction method illustrated in FIG. 19 extracts a minimum value from among the maximum luminance values in the high gradation region, and then only processes the maximum luminance values to the minimum value based on the extracted minimum value. Therefore, since the correction for the low gradation region or the gradation region is not achieved in the LEDs in the pixels, it is significantly insufficient to improve the overall image quality of the LED display.

As shown in FIG. 20, the first minimum value, which is the minimum value among the maximum luminance values, is extracted from the first correction data composed of the maximum luminance value of the high gradation region of each of the LEDs in the pixels, and the maximum luminance value is based on this. In addition to generating the first correction coefficients for the fields, the second minimum value, which is the minimum value among the maximum luminance values of the low gradation region, is obtained from the second correction data composed of the maximum luminance value of each low gradation region of the LEDs in the pixels. The luminance of the LEDs is corrected by extracting and generating second correction coefficients for the maximum luminance values of the low grayscale region based on this, and normalizing the luminance region of each of the LEDs in the entire pixel.

Unlike the conventional method, the luminance correction method of the present invention has an effect of improving overall image quality and uniformity by correcting not only the maximum luminance value of the LEDs, but also the low gradation region. Particularly, when compared to the characteristics of the low gradation region, that is, compared to the middle gradation region or the high gradation region, users of the LED display tend to perceive the luminance difference between pixels more prominently. The effect of reducing the tea is great.

In the luminance correction method of the present invention, the step of generating the correction data includes, for each of the LEDs R, G, and B in the pixels px, the maximum luminance values of the high gradation region by the light measurement unit 110 and And measuring the maximum luminance values of the low gradation region. As described above, when all the pixels of the LED display 1 are lit at once, to reduce the optical interference that may occur between adjacent pixels to improve the accuracy of the correction, for example, 9, 16, etc. pixels are included Grouped so that only one pixel in one group is lit at a time, so that it can be measured by the light measuring unit 110 in the absence of light interference from adjacent pixels. Therefore, when the number of pixels included in one group is 9, as shown in black in FIG. 18, the pixels that are lit are turned on by skipping two pixels in the row direction and two pixels in the column direction. The light is skipped and measured by the light measurement unit 110. That is, in FIG. 18, px11, px14, px17, ..., px41, px44, ... are lit at a time to measure the maximum luminance value and the minimum luminance value through the light measuring unit 110. . This process is repeated until measurements of the LEDs in all pixels of the LED display are made.

In the luminance correction method of the present invention, the step of generating the first correction coefficients compares the maximum luminance values of the high gradation region in the first correction data with the minimum value in the correction data measured / generated by the light measurement unit 110. Extracting the first minimum value by the extraction unit 120 and, based on the first minimum value extracted by the minimum value extraction unit 120, the correction coefficient generation unit 130 to the maximum of the high grayscale region in the first correction data It may be subdivided into steps of generating first correction coefficients for luminance values. In addition, the generating of the second correction coefficients may include comparing the maximum luminance values of the low grayscale region in the second correction data to extract the second minimum value with the minimum value extraction unit 120 and the minimum value extraction unit 120. Based on the second minimum value extracted by, the correction coefficient generation unit 130 may be subdivided into a step of generating second correction coefficients for the maximum luminance values of the low grayscale region in the second correction data.

In the luminance correction method of the present invention, the first correction coefficients are values obtained by dividing the first minimum value, which is the minimum value among the maximum luminance values of the high grayscale region in the first correction data, with the maximum luminance values of the high grayscale region in the first correction data. You can. For example, red LEDs (R) in px11, px12, px13, px14, px15, px16, px17, and px18 (numbered 1, 2, 3, 4, 5, 6, 7, 8 on the X axis in FIG. 20). The maximum luminance values of the high gradation regions of Max11, Max12, Max13, Max14, Max15, Max16, Max17, and Max18, respectively, and the minimum of the maximum luminance values of these high gradation regions, that is, the first minimum value is Max17 Assuming, the first correction coefficients are Max17 / Max11, Max17 / Max12, Max17 / Max13, Max17 / Max14, Max17 / Max15, Max17 / Max16, Max17 / Max17, and Max17 / Max18, respectively.

Meanwhile, the second correction coefficients may be values obtained by dividing the second minimum value, which is the minimum value among the maximum luminance values of the low grayscale region in the second correction data, with the maximum luminance values of the low grayscale region in the second correction data. For example, red LEDs (R) in px11, px12, px13, px14, px15, px16, px17, and px18 (numbered 1, 2, 3, 4, 5, 6, 7, 8 on the X axis in FIG. 20). The maximum luminance values of the low gradation regions of Max11 ', Max12', Max13 ', Max14', Max15 ', Max16', Max17 'and Max18', respectively, and the minimum values among the maximum luminance values of these low gradation regions. That is, assuming that the second minimum value is Max17 ', the second correction coefficients are Max17' / Max11 ', Max17' / Max12 ', Max17' / Max13 ', Max17' / Max14 ', Max17' / Max15 ', Max17', respectively. / Max16 ', Max17' / Max17 ', and Max17' / Max18 '.

21 is a view for explaining a process of detecting a first minimum value, a second minimum value, and a third minimum value from the correction data for each of the pixels of the LED display in the luminance correction method according to an embodiment of the present invention. Referring to FIGS. 17, 18, and 21 together, according to the luminance correction method of the present invention, in generating correction data, first correction data composed of maximum luminance values of high-gradation regions of LEDs, and low-gradation regions of LEDs The correction data may be generated to include the second correction data composed of the maximum luminance value of and the third correction data composed of the maximum luminance value of the middle gradation region which is an intermediate region of the high gradation region and the low gradation region of the LEDs. As described above, a third minimum value, which is the minimum value among the maximum luminance values of the grayscale region, is extracted from the third correction data composed of the maximum luminance values of the grayscale region, and the relay in the third correction data is based on the extracted third minimum value. Third correction coefficients may be generated for the maximum luminance values of the jaw region. For example, red LEDs (R) in px11, px12, px13, px14, px15, px16, px17, and px18 (on the X axis in FIG. 21, numbered 1, 2, 3, 4, 5, 6, 7, 8 Is assumed to be Max11 ”, Max12”, Max13 ”, Max14”, Max15 ”, Max16”, Max17 ”and Max18” respectively, and the minimum of the maximum luminance values of these grayscale areas, that is, the third Assuming that the minimum value is Max16 ”, the third correction factors are Max16” / Max11 ”, Max16” / Max12 ”, Max16” / Max13 ”, Max16” / Max14 ”, Max16” / Max15 ”, Max16” / Max16 ”, respectively. It becomes Max16 ”/ Max17”, and Max16 ”/ Max18”.

In this embodiment, the generating of the third correction coefficients includes: comparing the maximum luminance values of the grayscale areas in the third correction data to extract a third minimum value with the minimum value extraction unit 120, and extracting the minimum value Based on the third minimum value extracted by the unit 120, the correction coefficient generation unit 130 may be subdivided into a step of generating third correction coefficients for the minimum luminance values in the third correction data.

The luminance correction method according to the present invention is summarized in block diagram in FIG. 23. As shown in FIG. 23, the step of generating the first correction coefficients, the second correction coefficients and the third correction coefficients can be performed simultaneously in this order or in parallel, and finally the entirety of all pixels. The correction may be completed by normalizing the entire luminance region of the LEDs.

Furthermore, the method of generating the first correction coefficients, the second correction coefficients, and the third correction coefficients is not limited to the method presented above, but can be generated in any other way.

In addition, when measuring by the light measuring unit 110, when the luminance is measured by grouping the pixels to a predetermined number, the correction data is different from the above, the data corresponding to the red LED (R) of px11 in Figure 18 The LED 1 in FIG. 20, the data corresponding to the red LED (R) of px14 in FIG. 18 is the LED 2 in FIG. 20, the data corresponding to the red LED (R) of px17 in FIG. It can be LED 3.

In addition, since one pixel includes a red LED (R), a green LED (G), and a blue LED (B), the first correction data in the correction data is the maximum luminance of each of the red LEDs (R) in the pixels. 1-1 correction data composed of values, and 1-2 correction data composed of the maximum luminance values of each of the green LEDs (G) in pixels, and the maximum luminance values of each of the blue LEDs (B) in the pixels. It includes the first to third correction data. Accordingly, the first minimum value is a minimum value of 1-1, which is a minimum value among maximum luminance values in the 1-1 correction data, a minimum value of 1-2, which is a minimum value among maximum luminance values in the 1-2 correction data, and 1-3 includes the first to third minimum values, which are the minimum values among the maximum luminance values in the correction data. In addition, the first correction coefficients are first-first correction coefficients generated based on the first-first minimum value, first-second correction coefficients generated based on the first-second minimum value, and first-3 Contains 1-3 correction coefficients generated based on the minimum value.

In addition, the second correction data in the correction data is a 2-1 correction data composed of the minimum luminance value of each of the red LEDs R in the pixels, and the minimum luminance value of each of the green LEDs G in the pixels. 2-2 correction data, and 2-3 correction data, which are composed of the minimum luminance value of each of the blue LEDs B in the pixels. Accordingly, the second minimum value is a minimum value of 2-1, which is a minimum value among minimum luminance values in 2-1 correction data, a minimum value of 2-2, which is a minimum value among minimum luminance values in 2-2 correction data, and a second minimum value. 2-3, the minimum value of the minimum luminance value in the correction data is included. In addition, the second correction coefficients are 2-1 correction coefficients generated based on the 2-1 minimum value, 2-2 correction coefficients generated based on the 2-2 minimum value, and the second 2- 3 Includes 2-3 correction factors generated based on the minimum value.

In addition, as shown in FIG. 21, when the correction data includes the maximum luminance values of the grayscale region, the third correction data is configured as the maximum luminance value of each grayscale region of the red LEDs R in the pixels. 3-1 correction data, 3-2 correction data composed of the maximum luminance value of each grayscale region of the green LEDs G in pixels, and the grayscale of each of the blue LEDs B in pixels Contains 3-3 correction data composed of the maximum luminance value of the area. Accordingly, the third minimum value is a minimum value among 3-1 minimum values, which are the minimum values among the maximum luminance values of the grayscale region in the 3-1 correction data, and a minimum value among maximum luminance values of the grayscale regions in the 3-2 correction data. 3-3 minimum value, and 3-3 minimum value, which is the minimum value among the maximum luminance values of the grayscale region in the 3-3 correction data. In addition, the third correction coefficients, 3-1 correction coefficients generated based on the 3-1 minimum value, 3-2 correction coefficients generated based on the 3-2 minimum value, and 3-3 3-3 correction coefficients generated based on the minimum value.

In the above description, the 1-1 correction coefficients are correction coefficients corresponding to red in the high gradation region, the 1-2 correction coefficients are correction coefficients corresponding to green, and the 1-3 correction coefficients correspond to blue These are correction factors. And, the 2-1 correction coefficients are correction coefficients corresponding to red in the low grayscale region, the 2-2 correction coefficients are correction coefficients corresponding to green, and the 2-3 correction coefficients are correction coefficients corresponding to blue. . Accordingly, the normalization unit normalizes the red, green, and blue luminance values corresponding to the high gradation region by applying first correction coefficients to the luminance values in each of the high gradation regions of the red, green, and blue LEDs, The red, green and blue luminance values corresponding to the low gradation region, that is, the luminance values in the low gradation region of each of the red, green and blue LEDs are applied and normalized.

And, when the correction data includes the maximum luminance values of the grayscale region, the 3-1 correction coefficients are correction coefficients corresponding to red in the grayscale region, and the 3-2 correction coefficients are correction coefficients corresponding to green. , The 3-3 correction coefficients are correction coefficients corresponding to blue. Accordingly, the normalization unit normalizes by applying first correction coefficients to red, green, and blue luminance values corresponding to the high gradation region, that is, luminance values in each of the high gradation regions of the red, green, and blue LEDs. Then, the red, green, and blue luminance values corresponding to the low grayscale region, that is, the red, green, and blue LEDs, respectively, are normalized by applying second correction coefficients to the luminance values in the low grayscale region, and the grayscale region Red, green, and blue luminance values corresponding to, that is, red, green, and blue LEDs are normalized by applying third correction coefficients to the luminance values in each grayscale region.

22 illustrates a process of detecting a first minimum value, a second minimum value, a third minimum value, and a fourth minimum value from the correction data for each of the pixels of the LED display in the luminance correction method and system according to an embodiment of the present invention For the purpose of this drawing, the third minimum value and the fourth minimum value are the minimum values of the maximum luminance values in each by dividing the grayscale region into the first grayscale region and the second grayscale region.

In the embodiment illustrated in FIG. 21, the maximum luminance value of each grayscale region for each LED of the pixels is measured only once by the light measurement unit 110, but in the embodiment illustrated in FIG. 22, the grayscale region Is divided into a first grayscale region and a second grayscale region and measured in each to generate correction data to include a maximum luminance value in the first grayscale region and a maximum luminance value in the second grayscale region, After extracting the third minimum value and the fourth minimum value, the third correction coefficients and the fourth correction coefficients are generated to perform luminance correction. Further, the grayscale region may be further subdivided to measure the maximum luminance value for the LEDs in each of them, thereby generating correction data and then performing luminance correction.

Next, with reference to FIG. 24, a process of normalizing the entire region of the LEDs with the first correction coefficients and the second correction coefficients generated in FIG. 20 will be described. For example, when the process of normalizing LED 1 (LED 1 on the X axis) is described, the minimum value in the high gradation region, that is, the first minimum value is the maximum luminance value in the high gradation region of LED 7 Max17), the first correction coefficient to be applied to the LED 1 is Max17 / Max11. Accordingly, within the luminance region covered by the first correction coefficient, the first correction coefficient (such as 140 of FIG. 17) is applied to the entire brightness step (normally related to the magnitude of the current, and thus related to the magnitude of the current). Max17 / Max11) are all multiplied. The first correction coefficient to be applied to the LED 2 is Max17 / Max12, the first correction coefficient to be applied to the LED 3 is Max17 / Max13,… , The first correction coefficient to be applied to the LED 8 is Max17 / Max18, and each first correction coefficient may be applied to the luminance region covered by the first correction coefficient for all the LEDs. Here, the luminance region covered by the first correction coefficient may be the upper 50% of the entire luminance region of each of the LEDs as illustrated in FIG. 24, and in this case, the luminance region covered by the second correction coefficient may be lower 50 %to be. The luminance region covered by the first correction coefficient and the luminance region covered by the second correction coefficient are not limited to these ratios and may be applied at different ratios.

In addition, since the minimum value in the low gradation region, that is, the second minimum value is the maximum luminance value (Max17 ') in the low gradation region of the LED 7, the second correction coefficient to be applied to the LED 1 is Max17' / Max11 '. Accordingly, in the luminance region covered by the second correction coefficient, all of the second correction coefficients Max17 '/ Max11' are multiplied by the normalization unit (140 in FIG. 17) in the entire brightness step. The second correction coefficient to be applied to the LED 2 is Max17 '/ Max12', and the second correction coefficient to be applied to the LED 3 is Max17 '/ Max13',… , The second correction factor to be applied to the LED 8 is Max17 '/ Max18', and each second correction factor can be applied to the luminance region covered by the second correction factor for all the LEDs.

Next, with reference to FIG. 25, a process of normalizing the entire region of the LEDs with the first correction factors, the second correction factors, and the third correction factors generated in FIG. 21 will be described. For the normalization of the low gradation region and the high gradation region, the description of FIG. 24 may be applied as it is, so a duplicate description is omitted.

Since the minimum value in the grayscale region, that is, the third minimum value is the maximum luminance value in the grayscale region of the LED 6 (Max16 ”), the third correction coefficient to be applied to the LED 1 is Max16” / Max11 ”. Therefore, in the luminance region covered by the third correction coefficient, all of the third correction coefficients Max16 ”/ Max11” are multiplied by the normalization unit (140 in FIG. 17) in the entire brightness step. The third correction factor to be applied to the LED 2 is Max16 ”/ Max12”, and the third correction factor to be applied to the LED 3 is Max16 ”/ Max13”,… , The third correction coefficient to be applied to the LED 8 is Max16 '/ Max18 ", and each third correction coefficient may be applied to the luminance region covered by the third correction coefficient for all the LEDs. Here, the area covered by the third correction coefficient is a grayscale area in each of the LEDs. In addition, in FIG. 25, the upper 30% of the entire luminance area covers the area covered by the first correction coefficient, the lower 30% of the total luminance area covers the area covered by the second correction coefficient, and the area covered by the third correction coefficient is intermediate. Although illustrated as 40% of, it may be set to any number differently.

The brightness correction system and method of the present invention described above may be applied to various LED displays. For example, it can be applied to a micro LED display in which one pixel is composed of micro LEDs.

As described above, the luminance correction method and system of the present invention can overcome the disadvantages of the conventional method of correcting luminance based on the maximum luminance value, further improving the luminance expression and uniformity of the LED, and expect the overall image improvement effect. have.

17 to 25 described above are as follows.

1: micro LED display, 10: control PC, 100: luminance correction system, 110: light measurement unit, 120: minimum value extraction unit, 130: correction coefficient generation unit, 140: normalization unit, px: pixel.

Hereinafter, with reference to FIGS. 30 to 41, the LED display driver IC of the present invention and a method for adjusting luminance of the LED display using the same will be described. It is noted that the reference numerals in FIGS. 1 to 16 or 17 to 25 are somewhat overlapped, but the reference numerals in FIGS. 30 to 41 are limited to FIGS. 30 to 41.

Similar to the definition regarding the gray level of the image data described above, the gray level of the video signal in the following description with reference to FIGS. 30 to 41 is a low gray level in turn starting from a low region. ), Middle gray level (mid gray level) and high gray level (high gray level) can be divided into areas, the high gray level area is an area of 80% or more of the maximum luminance value of each LED, the low gray level area is high gray level The area is less than 30% of the maximum luminance value of the area, and the other areas are defined as a grayscale area. However, the range of the gradation region is divided for convenience of description, and is not necessarily limited to the above-described range.

30 is a basic block diagram of an LED driver IC 100 according to the present invention. Referring to Figure 30, according to one embodiment of the invention an input video signal (S _s) LED display driver IC (100) for adjusting the brightness of the presented LED display within the LED corresponding to an input image signal (S _s) receiving an input the input video signal (s _s), the control unit 110 to determine the gray level of the pulse width modulation in correspondence with the gradation of the input image signal (s _s) in response to the control of the control unit 110 (PWM) signals and pulse amplitude And a merge signal generator 120 that generates a merged signal (S _m ) in which a modulated (PAM) signal is merged. In addition, the LED display driver IC 100 is assigned to each column of pixels arranged in a matrix in the LED display unit 200 and responds to each of the merge signals S _m provided from the merge signal generator 120. The LED further includes a switching circuit unit 130 that operates to emit light at an appropriate luminance. In the merge signal generation unit 100, the pulse amplitude modulation signal generation unit 122 performs pulse amplitude modulation (PAM) on the pulse width modulation signal to generate a merge signal S _m or a pulse width modulation signal generation unit ( 121) performs a pulse width modulation on the pulse amplitude modulation signal to generate a merge signal S _m .

The present invention is to overcome the limitations of the conventional method of adjusting the luminance of the LEDs in the LED display only by changing the duty ratio in response to the input video signal through such a configuration, as well as pulse width modulation (PWM) as well as pulse amplitude ( By using pulse amplitude modulation (PAM) using the difference of pulse amplutude together, a merge signal in which a pulse amplitude modulation (PWM) signal and a pulse amplitude modulation (PAM) signal are merged is generated, thereby expressing the expressive power, particularly in a low gray scale region. The effect of reinforcing, reducing the flicker phenomenon, and improving the image quality in the HDR region can be seen.

31 is a block diagram of an LED display driver IC according to an embodiment of the present invention, and the merge signal generation unit 120 of FIG. 30 generates a pulse width modulation signal corresponding to the gray level of the input image signal S _s It includes a pulse width modulation signal generation unit 121 and a pulse amplitude modulation signal generation unit 122 for generating a pulse amplitude modulation signal (S _w ) corresponding to the gradation of the input image signal (S _s ). In the embodiment shown in FIG. 31, synchronization of signals is performed by the controller 110. That is, according to the control of the control unit 110, for example, an appropriate pulse width and duty ratio corresponding to the gradation of the input image signal S _s according to the clock signal CLK provided by the control unit 110 pulse width modulation signal (S _w), and is made up of a pulse amplitude adjustment to the pulse width modulation signal (S _w) having an appropriate pulse width and the duty ratio is generated by the remaining signal (S _m). First, the pulse width modulation signal generation unit 121 generates a pulse width modulation signal S _w corresponding to the gradation of the input image signal S _s , and then pulses the generated pulse width modulation signal S _w The amplitude modulated signal generator 122 adjusts the pulse amplitude to correspond to the gradation of the input image signal Ss, thereby generating a pulse amplitude modulated merge signal S _m . That is, pulse width modulation (PWM) is firstly performed by the pulse width modulation signal generation unit 121, and pulse amplitude modulation (PAM) is secondarily performed by the pulse amplitude modulation signal generation unit 122 to finally As a result, a merge signal S _m is generated. In the drawing, since the merge signal S _m is finally generated by the pulse amplitude modulation, the pulse amplitude modulation signal S _a and the merge signal S _m are displayed together.

32 is a view showing examples of the pulse width modulation signal (S _w ) and the pulse amplitude modulation signal (S _a ) in FIG. 31, (a) is an example of the pulse width modulation signal (S _w ), (b) Is an example of a pulse amplitude modulation signal S _a , that is, a merge signal S _m as a result.

First, looking at (a), each of the low gradation regions (gradation regions of less than 30%), the middle gradation regions (gradation regions of 30% or more and less than 80%), and the high gradation regions (gradation regions of 80% or more) Examples of the pulse width modulation signal S _w of each period are shown, and an appropriate duty ratio is determined within a predetermined pulse width corresponding to the gradation of the input video signal. As mentioned above, since these ranges are divided for convenience of description, the low grayscale region, the middle grayscale region, and the high grayscale region may be defined differently according to circumstances.

Next, in (b), an example of the pulse amplitude modulation signal S _a when the pulse amplitude is adjusted to correspond to the gray level of the input image signal Ss in turn, for example, the pulse amplitude for the high gray level area An example of a pulse amplitude modulation signal S _a when it is adjusted to correspond to the gradation of the input video signal S _s , and the pulse amplitude for both the low gradation region and the high gradation region is the input image signal S _s An example of the pulse amplitude modulation signal S _a when adjusted to correspond to the gradation of is shown. In the case of an arbitrary input image signal corresponding to a low grayscale region, examples of final merge signals after both pulse width modulation and pulse amplitude modulation are performed are illustrated in FIG. 41. In (b), only the case of 3-bit (2 ³ ) pulse amplitude modulation is illustrated, but the number of bits is not limited. Also, although not shown, the grayscale region may be adjusted to correspond to the grayscale of the input image signal S _s .

When applied to the low gradation region, the control unit 110 from the input image signal (S _s), the input receives a video signal (S _s) of the grayscale input image in the determination, the control unit 110 whether or not in the low gradation region When it is determined that the gradation of the signal S _s is within the low gradation region, the pulse width modulation signal generation unit 121 generates a pulse width modulation signal S _w to correspond to the gradation of the input image signal S _s . Subsequently, the pulse amplitude modulation signal generation unit 122 inputs the pulse amplitude of the pulse width modulation signal S _w generated by the pulse width modulation signal generation unit 121 in the first form of FIG. 32 (b). It can be adjusted to correspond to the gradation of the video signal (S _s ). If the controller 110 determines that the gradation of the input image signal S _s is not within the low gradation region, the pulse width modulation signal generation unit 121 corresponds to the gradation of the input image signal S _s . modulated signal (S _w), the generation, and pulse amplitude modulated by a pulse amplitude control in the signal generating unit 122 is not carried out, the resulting pulse width modulated by the PWM signal generation unit 121 signal (S _w ) Is applied to the switching circuit 130 to control the current and luminance of the LED.

In addition, in the case of applying the gradation region, the control unit 110 the input image signal (S _s) from the input receives a video signal (S _s) is high the determination and control section 110 whether or not in the gray scale area gradation of When it is determined that the gradation of the input image signal S _s is within the high gradation region, the pulse width modulation signal generation unit 121 generates a pulse width modulation signal S _w to correspond to the gradation of the input image signal S _s . After generation, the pulse amplitude modulation signal generator 122 generates the pulse amplitude of the pulse width modulation signal S _w generated by the pulse width modulation signal generator 121 as shown in FIG. 32 (b). With the input video signal (S _s ) It can be adjusted to correspond to the gradation. If the controller 110 determines that the gradation of the input image signal S _s is not within the high gradation region, the pulse width modulation signal generation unit 121 corresponds to the gradation of the input image signal S _s . The pulse width modulation signal S generated by the pulse width modulation signal generation unit 121 is generated by generating the modulation signal S _w and not adjusting the pulse amplitude by the pulse amplitude modulation signal generation unit 122. _w ) is applied to the switching circuit 130 to control the current and luminance of the LED.

In addition, when applied to both the low-gradation and high-gradation, the control unit 110 determines whether or not in the gray scale is the low gradation region and high gradation region for receiving the input video signal (S _s), the input image signal (S _s) Then, when the controller 110 determines that the grayscale of the input image signal S _s is within the low grayscale region or the high grayscale region, the pulse width modulation signal generator 121 generates the grayscale of the input image signal S _s a generating a pulse width modulated signal (S _w) to correspond to the later, the pulse amplitude of the pulse amplitude modulation signal generator 122 is a pulse width modulated signal (S _w) generated by the PWM signal generation unit 121 Can be adjusted to correspond to the gradation of the input video signal S _s . When the controller 110 determines that the gradation of the input image signal S _s is not within the low gradation region and the high gradation region, the pulse width modulation signal generation unit 121 corresponds to the gradation of the input image signal S _s As such, the pulse width modulation signal S _w is generated and the pulse amplitude modulation by the pulse amplitude modulation signal generation unit 122 is not performed, so that the pulse width modulation generated by the pulse width modulation signal generation unit 121 is performed. The signal S _w is applied to the switching circuit 130 to control the current and luminance of the LED.

As described above, in order to enhance the expressive power according to the brightness control of each of the LEDs in the LED display, by using both pulse width modulation and pulse amplitude modulation, it is possible to improve the disadvantages of the conventional method using only pulse width modulation. For example, in a method of adjusting the luminance of each of the LEDs using only the conventional pulse width modulation signal, assuming that the control covered by the pulse width modulation signal is a 12-bit (2 ¹² ) gray control, in the present invention, such pulse width modulation When the pulse amplitude modulation signal (for example, 6 bits (2 ⁶ )) is used in addition to the 12 bits (2 ¹² ) by the signal, 18 bits (2 ¹⁸ ) gray control becomes possible, so each of the LEDs It is possible to further increase the expressive power. Considering that control by the pulse width modulation signal alone is impossible with more than 16 bit (2 ¹⁶ ) gray control, the present invention can overcome this limitation by using the pulse width modulation signal and the pulse amplitude modulation signal together. .

33 is a block diagram of an LED driver IC according to another embodiment of the present invention. Referring to FIG. 33, the merge signal generation unit 120 of FIG. 30 includes a pulse width modulation signal generation unit 121 that generates a pulse width modulation signal corresponding to the gray level of the input image signal S _s , and an input image signal It includes a pulse amplitude modulation signal generation unit 122 for generating a pulse amplitude modulation signal (S _w ) corresponding to the gradation of (S _s ). As in the embodiment shown in FIG. 31, in this embodiment, synchronization of the signal is performed by the controller 110. That is, according to the control of the control unit 110, for example, a pulse amplitude modulation signal S _a having an appropriate pulse amplitude corresponding to the gradation of the input image signal S _s according to the clock signal CLK provided by the control unit 110 ), And adjustment of the duty ratio for this pulse amplitude modulation signal is performed. First, the pulse amplitude modulation signal generation unit 122 generates a pulse amplitude modulation signal S _a corresponding to the gradation of the input image signal S _s , and then pulses the generated pulse amplitude modulation signal S _a The width modulation signal generating unit 121 adjusts the pulse width and the duty ratio of the pulse to correspond to the gray level of the input video signal, thereby generating the final merge signal S _m . That is, pulse amplitude modulation (PAM) is primarily performed by the pulse amplitude modulation signal generation unit 122, and pulse width modulation (PWM) is performed secondarily by the pulse amplitude modulation signal generation unit 121 to finally perform As a result, a merge signal S _m is generated. In the drawing, since the merge signal S _m is finally generated by the pulse width modulation, the pulse width modulation signal S _w and the merge signal S _m are displayed together.

FIG. 34 is a view showing examples of the pulse amplitude modulation (S _a ) and the pulse width modulation signal (S _w , here, the final merge signal (S _m )) in FIG. 33, and (a) is the pulse amplitude modulation signal (S). _a ) is an example, and (b) is an example of a pulse width modulation signal S _w , that is, a final merge signal S _m .

First, looking at (a), each of the low gradation regions (gradation regions of less than 30%), the middle gradation regions (gradation regions of 30% or more and less than 80%), and the high gradation regions (gradation regions of 80% or more) shows examples of pulse amplitude modulation signal (S _a) of each period. The appropriate pulse amplitude is first determined to correspond to the gradation of the input image signal in each gradation region.

Next, in (b), when the input video signal is in the low gradation region in turn, the duty ratio within a predetermined pulse width is input to the pulse amplitude modulation signal generated by determining the pulse amplitude in (a). Example of pulse width modulation signal S _a when adjusted to correspond to the gradation of S _s ), when the input image signal is within the low gradation region, pulse amplitude is determined in (a) to the generated pulse amplitude modulation signal. For example, an example of the pulse width modulation signal S _w when the duty ratio is adjusted to correspond to the gradation of the input video signal S _s within a predetermined pulse width, and for both the low gradation region and the high gradation region An example of the pulse width modulation signal S _w when the duty ratio is adjusted to correspond to the gradation of the input video signal S _s within the pulse width of? Although not illustrated, the grayscale region may be adjusted to correspond to the grayscale of the input image signal S _s .

For example, if applied to the low gradation region, the control unit 110 receives the input image signal (S _s), the gray level of the input image signal (S _s), and determines whether or not in the low gradation region, the control unit (110 ), If it is determined that the gradation of the input image signal S _s is within the low gradation region, the pulse amplitude modulation signal generation unit 122 corresponds to the gradation of the input image signal S _s , so that the pulse amplitude modulation signal S _a ), The pulse width modulation signal generator 121 generates a duty ratio of the pulse amplitude modulation signal S _a generated by the pulse amplitude modulation signal generator 122 with the first in FIG. 34 (b). Similarly, it can be adjusted to correspond to the gradation of the input video signal S _s . If the controller 110 determines that the gradation of the input image signal S _s is not within the low gradation region, the pulse amplitude modulation signal generation unit 122 does not control the pulse amplitude, and the pulse width modulation signal generation unit By generating the pulse width modulation signal (S _w ) directly at 121 and providing it to the switching circuit unit 123 side, the current and luminance of the LEDs can be adjusted.

In addition, in the case of applying the gradation region, the control unit 110 the input image signal (S _s) from the input receives a video signal (S _s) is high the determination and control section 110 whether or not in the gray scale area gradation of When it is determined that the gradation of the input image signal S _s is within the high gradation region, the pulse amplitude modulation signal generation unit 122 generates a pulse amplitude modulation signal S _a to correspond to the gradation of the input image signal S _s . After generation, the pulse width modulation signal generation unit 121 inputs the duty ratio of the pulse amplitude modulation signal S _a generated by the pulse amplitude modulation signal generation unit 122 as shown in FIG. 34 (b). It can be adjusted to correspond to the gradation of the video signal (S _s ). If the controller 110 determines that the gradation of the input image signal S _s is not within the low gradation region, the pulse amplitude modulation signal generation unit 122 does not control the pulse amplitude, and the pulse width modulation signal generation unit By generating the pulse width modulation signal (S _w ) directly at 121 and providing it to the switching circuit unit 123 side, the current and luminance of the LEDs can be adjusted.

When applied to both the low gradation region and high gradation region, the control section 110 whether or not in the gray scale is the low gradation region and high gradation region of the input image signal (S _s), the input receives a video signal (S _s) If it is determined and the control unit 110 determines that the gray level of the input image signal S _s is in the low gray level region or in the high gray level region, the pulse amplitude modulation signal generation unit 122 determines whether the gray level of the input image signal S _s is After generating the pulse amplitude modulation signal S _a corresponding to the gradation, the duty of the pulse amplitude modulation signal S _a generated by the pulse amplitude modulation signal generation unit 122 by the pulse amplitude modulation signal generation unit 121 The ratio may be adjusted as the third of FIG. 34 (b) to correspond to the gradation of the input image signal S _s . If the controller 110 determines that the gradation of the input image signal S _s is neither within the low gradation region nor within the high gradation region, the pulse amplitude is not adjusted by the pulse amplitude modulation signal generation unit 122. Instead, the pulse width modulation signal generation unit 121 directly generates a pulse width modulation signal S _w and provides it to the switching circuit unit 123 to control the current and luminance of the LEDs. Even in this embodiment, only the case where the input video signal is in the low gray level area and / or the high gray level area is illustrated, but it can also be applied to the gray level area.

As described above, in order to enhance the expressive power according to the brightness control of each of the LEDs in the LED display, by using both pulse width modulation and pulse amplitude modulation, it is possible to improve the disadvantages of the conventional method using only pulse width modulation.

35 to 38 are block diagrams for explaining the LED driver IC according to another embodiment of the present invention. Specifically, FIG. 35 is a block diagram of the LED driver IC according to another embodiment of the present invention. 36 is a view for explaining a process of generating a merge signal applied only when the input image signal is in a low grayscale region in the embodiment of FIG. 35, and FIG. 37 is a high grayscale region of the input image signal in the embodiment of FIG. FIG. 38 is a view for explaining a process of generating a merge signal that is applied only in the case of FIG. It is a drawing for explaining.

Referring to Figure 35, the remaining signal generator 120 and the input image signal (S _s) of in correspondence to the gradation generating a pulse width modulation signal for generating a pulse width modulated signal 121, the input image signal (S _s ) Corresponding to the grayscale of the pulse amplitude modulation signal generation unit (S _w ) for generating a pulse amplitude modulation signal (S _w ) and the pulse width modulation signal generated by the pulse width modulation signal generation unit (121) (S _w ) and And a merge unit 123 for merging the pulse amplitude modulation signal S _a generated by the pulse amplitude modulation signal generation unit under the control of the controller 110 to generate a merge signal S _m . The merge unit 123 generates a pulse width modulation signal S _w and a pulse amplitude modulation signal generation unit generated by the pulse width modulation signal generation unit 121 according to the synchronization clock signal CLK provided from the control unit 110. The pulse amplitude modulation signal (S _a ) generated by (122) is merged.

As shown in FIG. 36, when applied when the input image signal S _s is in the low grayscale region, the pulse width modulation signal ( S _w ), and for the low grayscale region, the pulse amplitude modulation signal generation unit 122 generates a pulse amplitude modulation signal S _a , and the merge signal generation unit 123 merges these signals to switch the circuit unit ( 130) Adjusts the current and brightness of the LEDs by providing them to the side.

In addition, as illustrated in FIG. 37, when applied when the input image signal S _s is in the high grayscale region, the pulse width modulation is generated by the pulse width modulation signal generation unit 121 for the remaining regions except the high grayscale region. The signal S _w is generated, and the pulse amplitude modulation signal generation unit 122 generates a pulse amplitude modulation signal S _{a for the} high gradation region, and the merge signal generation unit 123 merges these signals for switching. Provided to the circuit 130, the current and luminance of the LEDs are adjusted.

In addition, as shown in FIG. 38, when applied when the input image signal S _s is in the low grayscale region or in the high grayscale region, in the remaining regions (grayscale region) except the low grayscale region and the high grayscale region For the pulse width modulation signal generation unit 121 generates a pulse width modulation signal (S _w ), and for the high gradation region, the pulse amplitude modulation signal generation unit 122 generates a pulse amplitude modulation signal (S _a ), By merging these signals from the merge signal generator 123 and providing them to the switching circuit 130, the current and luminance of the LEDs are adjusted.

Similarly, in this embodiment, only the case where the input video signal is in the low gray level region and / or the high gray level region is illustrated, but it can also be applied to the gray level region.

39 is a gamma curve for showing the disadvantages of the conventional method of controlling the luminance of the LEDs in the LED display only with the pulse width modulation method, and FIG. 40 is the present invention using the pulse width modulation signal and the merge signal of the pulse amplitude modulation signal. It is a drawing to show the characteristics of.

First, referring to FIG. 39, a curve with gamma (γ) = 2.8 will be considered. In the ^8- bit (2 ⁸ ) gray control using a conventional pulse width modulation signal, the clock time is 31.25 ms at 32 MHz of gray clock (GCLK). In order to express 2 ¹⁰ , 31.25 * 2 ¹⁰ ㎱, that is, 32 시간 of time is required, and if you want to express 2 ¹⁶ using this, 32 ㎲ * 2 ^6, that is, 2.048 시간 of time is required. Therefore, a refresh rate of about 488 hz can be obtained. Therefore, when only pulse width modulation is used, there is a problem of sacrificing the refresh rate, and accordingly, a flicker phenomenon may occur, thereby degrading image quality. These flickers appear prominently in the low-gradation domain of the patent, which affects image quality.

In addition, as mentioned above and as can be seen from the gamma (γ = 2.8) curve, it is necessary to further classify the control signals on the driving IC side for fine expression in the low gradation region. have.

Therefore, in the present invention, as shown in FIG. 40, by using the pulse width modulation and the pulse amplitude modulation together to generate a merge signal, it is possible to overcome the conventional limitations.

According to an embodiment of the present invention, the merge signal S _m generated by the merge signal generation unit 100 in FIG. 30 is the number of bits of the pulse width modulation signal generated by the pulse width modulation signal generation unit 121. It may be a signal having a fineness corresponding to the sum of the number of bits of the pulse amplitude modulation generated by the pulse amplitude modulation signal generation unit 122. The fineness, in this specification, the degree of the number of bits included in the pulse width modulation signal in the case of a pulse width modulation signal, and, in the case of a pulse amplitude modulation signal, how many bits are included in the pulse amplitude modulation signal. It is defined as a term indicating the degree of. In this case, the merge signal S _m has a refresh rate corresponding to the number of bits of the pulse width modulated signal. The fineness and refresh rate will be described with reference to FIG. 40 by way of example.

Referring to FIG. 40 presented as an example of the method according to the present invention, looking at a curve with gamma (γ) = 2.8, a 10-bit (2 ¹⁰ ) gray control using a pulse width modulation signal and a 6-bit using a pulse amplitude modulation signal ( ²⁶⁾ in the control gray, gray clock (GCLK) from 32Mhz clock time is 31.25㎱, and so in order to express 2 ^¹⁰ 31.25 * 2 ¹⁰ ㎱, i.e. the time required 32㎲, the refresh rate is 1 / 32㎲ That is, 31,250hz. Even if fine adjustment is possible by adding as much as ⁶ bits (2 ⁶ ) using the pulse amplitude modulation signal, when 16-bit gray control is performed using only the pulse amplitude modulation signal (in this case, 31.25 * 2 ¹⁶ 요구 is required, the refresh rate is Compared with the conventional pulse width modulation alone, a much higher refresh rate can be achieved in comparison with 2048 Hz of time required, resulting in a refresh rate of 488 hz).

Accordingly, it is possible to finely adjust the luminance, particularly in a low grayscale region, thereby improving expression. In addition, by improving the expressive power in HDR (High Dynamic Range), it is possible to see the overall image improvement effect of the LED display device, and has an advantage that can be applied to 3D display products requiring high-speed refresh.

As described above, the LED display driver IC according to the present invention has conventionally tried to overcome the limitation in controlling the luminance of the LEDs using only the pulse width modulation signal. The LED display driver IC according to the present invention can be finely adjusted as much as the number of bits by the pulse width modulation signal in addition to the number of bits by the conventional pulse width modulation signal. For example, if the number of bits by the pulse width modulation signal is 12 bits (2 ¹² ) and the number of bits by the pulse amplitude modulation signal is 6 bits (2 ⁶ ), fine adjustment of 18 bits (2 ¹⁸ ) is performed. It becomes possible. In addition, by adjusting the luminance of the LEDs using pulse amplitude modulation to correspond to the increase in luminance according to the increase in the refresh rate, it is possible to realize the best display image quality. In addition, the present invention has the advantage that the pixels can be applied to a high-resolution full-color LED display implemented with micro LEDs, and can be applied to high-speed frame products such as 3D products by implementing high-speed refresh.

The brightness control method of the LEDs in the LED display according to the present invention includes: (1) determining a gradation level of the input image signal by a control unit, and (2) pulse corresponding to a gradation level of the input image signal depending on the determination of the control unit. Generating a width modulated (PWM) signal, (3) generating a pulse amplitude modulated (PAM) signal corresponding to the gradation of the input image signal depending on the determination of the controller, (4) the pulse width modulated signal And merging the pulse amplitude modulation signal to generate a merge signal, and (5) adjusting the luminance of the LEDs with the merge signal. In the above steps, steps (2) and (3) may be performed in the order of steps (2)-(3), or (3)-(2), and may be performed in parallel with each other. It might be.

For example, in the determining step ((1) step) of the control unit, the control unit determines whether the gray level of the input image signal is within a low gray level region, and the control unit determines that the gray level of the input image signal is within the low gray level region. If it is determined that there is, in the step of generating the pulse width modulation signal (step (2)), generating a pulse width modulation signal corresponding to the gradation of the input image signal, and then generating the pulse amplitude modulation signal ( In step (3), the pulse amplitude of the pulse width modulated signal generated in the step of generating the pulse width modulated signal may be adjusted to correspond to the gradation of the input image signal.

In addition, in the determining step ((1) step) of the control unit, the control unit determines whether the gray level of the input image signal is in a high gray level region, and the control unit determines that the gray level of the input image signal is within the high gray level region. If it is determined that there is, in the step of generating the pulse width modulation signal (step (2)), generating a pulse width modulation signal corresponding to the gradation of the input image signal, and then generating the pulse amplitude modulation signal ( In step (3), the pulse amplitude of the pulse width modulated signal generated in the step of generating the pulse width modulated signal may be adjusted to correspond to the gradation of the input image signal.

In addition, in the determination step ((1) step) of the control unit, the control unit determines whether the gray level of the input image signal is within a low gray level region and a high gray level region, and the gray level of the input image signal is determined by the control unit. When it is determined that the signal is within the low grayscale region or the high grayscale region, in the step of generating the pulse width modulation signal (step (1)), after generating a pulse width modulation signal corresponding to the grayscale of the input image signal, the In the step of generating a pulse amplitude modulated signal (step (2)), the pulse amplitude of the pulse width modulated signal generated in the step of generating the pulse width modulated signal may be adjusted to correspond to the gradation of the input image signal.

Alternatively, in the determining step ((1) step) of the control unit, the control unit determines whether the gray level of the input image signal is within a low gray level region, and the control unit determines that the gray level of the input image signal is the low gray level. If it is determined that the signal is within the range, in the step of generating the pulse amplitude modulation signal (step (3)), after generating a pulse amplitude modulation signal corresponding to the gray level of the input image signal, generating the pulse width modulation signal In step ((2) step), the duty ratio of the pulse amplitude modulated signal generated in the step of generating the pulse amplitude modulated signal may be adjusted to correspond to the gradation of the input image signal.

In addition, in the determining step ((1) step) of the control unit, the control unit determines whether the gray level of the input image signal is in a high gray level region, and the control unit determines that the gray level of the input image signal is within the high gray level region. If it is determined that there is, in the step of generating the pulse amplitude modulation signal (step (3)), generating a pulse amplitude modulation signal corresponding to the gradation of the input video signal, and then generating the pulse width modulation signal ( In step (2), the duty ratio of the pulse amplitude modulated signal generated in the step of generating the pulse amplitude modulated signal may be adjusted to correspond to the gradation of the input video signal.

In addition, in the determination step ((1) step) of the control unit, the control unit determines whether the gray level of the input image signal is within a low gray level region and a high gray level region, and the gray level of the input image signal is determined by the control unit. When it is judged that it is within the low grayscale region or the high grayscale region, in the step of generating the pulse amplitude modulation signal (step (3)), after generating a pulse amplitude modulation signal corresponding to the grayscale of the input image signal, the In the step of generating a pulse width modulated signal (step (2)), the duty ratio of the pulse amplitude modulated signal generated in the step of generating the pulse amplitude modulated signal may be adjusted to correspond to the gradation of the input image signal.

Reference numerals of FIGS. 30 to 41 described above are as follows.

100: LED driver IC, 110: control unit, 120: merge signal generation unit, 121: pulse width modulation signal generation unit, 122: pulse amplitude modulation signal generation unit, 123: merge unit, 130: switching circuit unit.

Claims

A method of correcting luminance of an LED display in which a plurality of pixels in which the first LED, the second LED, and the third LED are formed as one pixel are arrayed,

(a) obtaining pixel data for each location at different positions in front of the LED display;

(b) determining a reference value for each location in each pixel data for each location obtained in step (a);

(c) determining correction coefficients for each of the pixels based on a reference value for each position determined in step (b); And

(d) combining the correction coefficients for each position determined in the step (c) at a predetermined ratio and applying them to all pixels of the LED display; the method of correcting the luminance of the LED display.
The method according to claim 1, wherein the pixel data for each location comprises a luminance value for each of the LEDs in the pixel.
The method according to claim 2, wherein the reference value for each location is the lowest luminance value in the pixel data for each location.
The method according to claim 1, wherein the correction coefficients for each position is a ratio of pixel data for each position of the LEDs in the plurality of pixels with respect to the reference value for each position.
The method according to claim 1, wherein the ratio of the correction coefficients for each position to the total number of pixels is the same, characterized in that the luminance correction method of the LED display.
The method according to claim 1, wherein the pixel data for each location includes first pixel data, second pixel data, and third pixel data for each location at the different locations, and the first pixel data is for each of the first LEDs. The luminance of the LED display, wherein the second pixel data includes the luminance value of each of the second LEDs, and the third pixel data includes the luminance value of each of the third LEDs. How to correct luminance.
The method according to claim 6, The reference value for each location includes a first reference value, a second reference value, and a third reference value for each location at the different locations, and the first reference value is the lowest luminance in the first pixel data. Value, the second reference value is the lowest luminance value in the second pixel data, and the third reference value is the lowest luminance value in the third pixel data.
The method according to claim 7, wherein the correction factors for each location, the first correction coefficients for each location at the different positions, the second correction coefficients and the third correction coefficients, wherein the first correction coefficients are the first correction coefficients The ratio of the luminance value of each of the first LEDs to the reference value is the ratio, and the second correction coefficients are the ratio of the luminance value of each of the second LEDs to the second reference value, and the third correction factors are And the luminance value of each of the third LEDs relative to the third reference value.
The method according to claim 1, Different positions in front of the LED display in step (a), characterized in that it comprises a left position, a central position to the right than the left position, and a right position to the right than the center position. , How to correct the luminance of the LED display.
The method according to claim 9, wherein the pixel data for each location,

It includes the first pixel data, the second pixel data and the third pixel data obtained at the left position, the fourth pixel data, the fifth pixel data and the sixth pixel data obtained at the central position, and the right 7th pixel data, 8th pixel data, and 9th pixel data acquired at the position,

The first pixel data, the fourth pixel data, and the seventh pixel data include luminance values of the first LEDs, and the second pixel data, the fifth pixel data, and the eighth pixel data are second LEDs. The luminance correction method of the LED display, wherein each of the third pixel data, the sixth pixel data, and the ninth pixel data includes a luminance value of each of the third LEDs.
The method according to claim 10, wherein the reference value for each location includes a first reference value, a second reference value, a third reference value, a fourth reference value, a fifth reference value, a sixth reference value, a seventh reference value, an eighth reference value, and a ninth reference value,

The first reference value is the lowest luminance value in the first pixel data, the second reference value is the lowest luminance value in the second pixel data, and the third reference value is the lowest luminance value in the third pixel data. A luminance value, the fourth reference value is the lowest luminance value in the fourth pixel data, the fifth reference value is the lowest luminance value in the fifth pixel data, and the sixth reference value is the sixth pixel data The lowest luminance value within, the seventh reference value is the lowest luminance value within the seventh pixel data, the eighth reference value is the lowest luminance value within the eighth pixel data, and the ninth reference value is the A luminance correction method of the LED display, characterized in that it is the lowest luminance value in the ninth pixel data.
The method according to claim 11, The position-specific correction coefficients, first correction coefficients, second correction coefficients, third correction coefficients, fourth correction coefficients, fifth correction coefficients, sixth correction coefficients, seventh Correction factors, eighth correction factors and ninth correction factors,

The first correction coefficients are the ratio of the luminance values of each of the first LEDs to the first reference value, and the second correction coefficients are the luminance values of each of the second LEDs to the second reference value. Ratio, and the third correction coefficients are ratios of luminance values of each of the third LEDs to the third reference value,

The fourth correction coefficients are ratios of luminance values of each of the first LEDs to the fourth reference value, and the fifth correction coefficients are ratios of luminance values of each of the second LEDs to the fifth reference value, The sixth correction coefficients are ratios of luminance values of each of the third LEDs to the sixth reference value,

The seventh correction coefficients are the ratio of the luminance values of each of the first LEDs to the seventh reference value, and the eighth correction coefficients are the ratio of the luminance values of each of the second LEDs to the eighth reference value, The ninth correction coefficients are the ratio of the luminance value of each of the third LEDs to the ninth reference value, the luminance correction method of the LED display.
The method of claim 12, wherein in the step (d), applying the first correction factors to the ninth correction factors to all pixels of the LED display,

Each of the first to third correction factors is applied to each of the first to third LEDs in the first pixel, and the first to third to third LEDs in the second pixel adjacent to the first pixel are applied. Characterized in that each of the fourth correction factor to the sixth correction factor is applied, and each of the seventh correction factor to the ninth correction factor is applied to each of the first and third LEDs in the third pixel adjacent to the second pixel. The brightness correction method of the LED display.
In the luminance correction system of the LED display in which a plurality of pixels in which at least the first LED, the second LED, and the third LED are formed as one pixel are arranged in the lateral and longitudinal directions,

A pixel data unit that acquires pixel data for each position of the LED display at different positions including the right, center, and left sides of the front of the LED display;

A reference value setting unit for determining a reference value for each location from the pixel data for each location obtained from the pixel data unit;

A correction coefficient setting unit for determining a correction coefficient for each location for each of the plurality of pixels according to a reference value for each location acquired by the reference value setting unit; And

And a luminance correction unit that combines the correction factors for each position obtained by the correction factor setting unit at a predetermined ratio and applies them to all of a plurality of pixels.
15. The method of claim 14, wherein the pixel data unit, The first LED, the second LED and the third LED constituting the plurality of pixels, characterized in that for obtaining a luminance value for each, the luminance correction system of the LED display .
The luminance correction system of an LED display according to claim 14, wherein the reference value setting unit selects the lowest luminance value from pixel data for each location of the plurality of pixels.
The method according to claim 14, The correction coefficient setting unit, the ratio of the luminance value of each of the first LED, the second LED and the third LED obtained in the pixel data unit with respect to the reference value set by the reference value setting unit (Ratio) Characterized in that, to set the luminance correction system of the LED display.
The luminance correction system of the LED display according to claim 14, wherein the luminance correction unit is applied so that a ratio of correction coefficients for each location of the plurality of pixels is the same.
A luminance correction system of an LED display in which a plurality of pixels in which at least the first LED, the second LED, and the third LED are formed as one pixel are arrayed,

Measure the luminance values of the first LED, the second LED and the third LED on the left side of the front of the LED display, and measure the luminance values of the first reference value, the second reference value, and the third reference value for the first LED and the second reference value. A first correction coefficient, a second correction coefficient, and a third correction coefficient that form a ratio of the luminance values of the two LEDs and the third LED;

Measure the luminance values of the first LED, the second LED, and the third LED in the center of the front of the LED display, and measure the luminance values of the fourth reference value, the fifth reference value, and the sixth reference value, respectively. A fourth correction coefficient, a fifth correction coefficient, and a sixth correction coefficient that form a ratio of the luminance values of the two LEDs and the third LED; And

Measure the luminance values of the first LED, the second LED, and the third LED on the right side of the front of the display of the LED, and measure the luminance values of the seventh reference value, the eighth reference value, and the ninth reference value, respectively. And a seventh correction coefficient, an eighth correction coefficient, and a ninth correction coefficient, which form a ratio of the luminance values of the second LED and the third LED.

Compensating the luminance values of the first LED, the second LED and the third LED in the pixels of the LED display by combining the first to eighth correction coefficients in the same ratio, the luminance correction system of the LED display .
The method according to claim 19, wherein the first to ninth reference value is characterized in that the lowest luminance value of the luminance value of each of the first LED, the second LED and the third LED measured at the left, middle and right sides, Luminance correction system of LED display.