KR20190000649A - Video wall device and driving method of the same - Google Patents

Abstract

The present invention relates to a video wall device and a driving method thereof, wherein the video wall device includes a plurality of display devices and a main control unit for outputting an image signal to the display devices. The main control unit includes: an average image level calculation unit which calculates an average image level of an image outputted from a display panel of each display device; a peak luminance control unit which controls peak luminance of each display panel on the basis of an image average level; a Gaussian curve setting unit which sets luminance of each display panel to follow a Gaussian curve on the basis of the average image level; and a gain determination unit which determines a gain of luminance of each display panel. Accordingly, a difference in luminance of each display panel is reduced to be equal to or less than a recognition level of a viewer. The image quality of the entire image of the video wall device can be increased. In addition, luminance of the entire display panel is increased, thereby increasing luminance of the entire video wall device.

Description

TECHNICAL FIELD [0001] The present invention relates to a video wall apparatus,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video wall apparatus and a driving method thereof, and more particularly, to a video wall apparatus and a method of driving the same, in which luminance of a display panel provided in a video wall apparatus is set according to a Gaussian curve, And a method of driving the same.

BACKGROUND ART Demands for a display device for displaying an image have been increasing in various forms as an information society has developed. Recently, a liquid crystal display device, a plasma display panel, an organic light emitting display device Organic Light Emitting Display Device) are being utilized.

Although the screen size of the display device has been continuously increased due to technological advancement, there has been a limit to realizing a very large screen such as an electronic blackboard and a billboard.

Therefore, a video wall device for connecting a plurality of display devices has been developed in order to realize a very large screen. A plurality of display devices provided in the videowall apparatus each display a plurality of divided images obtained by dividing one image.

Here, due to the plurality of different divided images, the brightnesses of the display panels of the plurality of display devices provided in the video wall apparatus are different from each other. Therefore, the luminance of the video wall apparatus is not uniform as a whole, and the quality of the output image is degraded.

Therefore, in order to solve such a problem, the brightness of a plurality of display panels is set to the minimum brightness value among the brightnesses of the display panels of the plurality of display devices provided in the videowall apparatus.

However, when the luminance of the plurality of display panels is set to the minimum luminance value, the luminance of the video wall device is reduced as a whole, and the visibility of the output image is lowered.

That is, the video wall apparatus has a problem in that the total luminance of the video wall apparatus is degraded without being uniform due to a plurality of display apparatuses outputting different images.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a video wall apparatus and a method of driving the same, which can increase the luminance of a video wall apparatus uniformly by setting the luminance of a display panel provided in a videowall apparatus according to a Gaussian curve .

The problems of the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a video wall apparatus including a plurality of display devices and a main controller for outputting video signals to a plurality of display devices, An image average level calculating section for calculating an image average level of an image outputted from the display panel, a peak luminance control section for controlling the peak luminance of each display panel based on the image average level, A Gaussian curve setting unit for setting the luminance of the panel so as to follow the Gaussian curve, and a gain determining unit for determining the gain of the luminance of each display panel.

According to an aspect of the present invention, there is provided a method of driving a videowall apparatus, the method comprising: calculating an image average level of an image output from each display panel; A peak luminance control step of controlling the peak luminance of each display panel, a Gaussian curve setting step of setting the luminance of each display panel so as to follow the Gaussian curve based on the image average level, And a gain determining step of determining a gain.

The details of other embodiments are included in the detailed description and drawings.

The present invention can reduce the difference in total luminance among a plurality of display panels even if there is a large difference in image average level (APL) between a plurality of display panels. Thus, the difference in total luminance of each display panel is reduced below the perception level of the viewer, so that the image quality of the entire image of the video wall apparatus can be improved.

In addition, the present invention has an effect of increasing the luminance of the entire video wall device by increasing the gain of the luminance of the entire display panel, taking into consideration the area of interest, the complexity of the image, and the consumption current values of the respective display panels.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the specification.

1 is a schematic block diagram for explaining a video wall apparatus according to an embodiment of the present invention.
2 is a schematic block diagram for explaining a plurality of display devices provided in a videowall apparatus according to an embodiment of the present invention.
3 is a circuit diagram for explaining driving of pixels arranged in a display device provided in a videowall apparatus according to an embodiment of the present invention.
4 is a schematic block diagram for explaining a main control unit included in a videowall apparatus according to an embodiment of the present invention.
5 is a graph illustrating an operation of a peak luminance controller included in a videowall apparatus according to an exemplary embodiment of the present invention.
6 is a graph illustrating the brightness of a display panel included in a videowall apparatus according to an exemplary embodiment of the present invention.
FIG. 7 is a schematic block diagram illustrating a gain determiner included in a videowall apparatus according to an exemplary embodiment of the present invention. Referring to FIG.
8 is a view showing a plurality of display areas arranged on a display panel provided in a videowall apparatus according to an embodiment of the present invention.
9 is a flowchart illustrating a method of driving a videowall apparatus according to an embodiment of the present invention.
10 is a flow chart for explaining gain determination steps of a method of driving a videowall apparatus according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

In the following description of the present invention, detailed description of known related arts will be omitted when it is determined that the gist of the present invention may be unnecessarily obscured by the present invention. Where the terms "comprises", "having", "done", and the like are used in this specification, other portions may be added unless "only" is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

 The first, second, etc. are used to describe various components, but these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

Like reference numerals refer to like elements throughout the specification.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other partially or entirely and technically various interlocking and driving is possible as will be appreciated by those skilled in the art, It may be possible to cooperate with each other in association.

Various embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

1 is a schematic block diagram for explaining a video wall apparatus according to an embodiment of the present invention.

Referring to FIG. 1, in an embodiment of the present invention, a videowall apparatus 1000 includes a plurality of display devices 100 to 900 and a main control unit 1010. For example, in FIG. 1, a video wall apparatus 1000 is configured by arranging a plurality of display apparatuses 100 to 900 in the form of a 3X3 tile. 3, the video display device 1000 is configured by arranging the nine display devices 100 to 900 in the form of a 3X3 tile. However, the number of the display devices constituting one video wall device 1000 There is no restriction on the layout structure.

The main control unit 1010 receives the input signal Input from the external host system and outputs the video signal VS to each of the plurality of display devices 100 to 900. [ Here, the input signal Input is a signal for displaying one full image output to the video wall device 1000, and the image signal VS is a signal for displaying a plurality of display devices 100 to 900, And is a signal for displaying a divided image. Therefore, the plurality of display apparatuses 100 to 900 receive a plurality of video signals VS individually, and output divided video images, respectively. Thus, the divided images displayed on the display devices 100 to 900 of the videowall apparatus 1000 are combined to implement the entire image.

2 is a schematic block diagram for explaining a plurality of display devices provided in a videowall apparatus according to an embodiment of the present invention.

Hereinafter, a first display device 100 among a plurality of display devices 100 to 900 provided in the videowall apparatus 1000 will be described as an example.

Referring to FIG. 2, the first display device 100 includes a display panel 110, a data driver 120, a gate driver 130, and a timing controller 140.

The display panel 110 includes a plurality of gate lines GL1 to GLm and a plurality of data lines DL1 to DLn formed in a matrix form on a substrate using glass or plastic. A plurality of pixels Px are defined at intersections of the plurality of gate lines GL1 to GLm and the data lines DL1 to DLn.

Each pixel Px of the display panel 110 is provided with at least one thin film transistor. The gate electrode of the thin film transistor is connected to the gate line GL, and the source electrode thereof is connected to the data line DL.

The first display device 100 may be an organic light emitting display. In this case, current is applied to the organic light emitting diode (OLED in FIG. 3) arranged in the plurality of pixels Px, and excitons are generated by the combination of the emitted electrons and the holes. Then, the excitons emit light to realize the gray scale of the OLED display. Details of this will be described later with reference to Fig.

As described above, the first display device 100 is not limited to the organic light emitting display device, and may be various display devices such as a liquid crystal display device.

Each pixel Px may include a plurality of sub-pixels, and each sub-pixel may emit light of a specific color. For example, the plurality of sub-pixels may be composed of a red sub-pixel that emits red, a green sub-pixel that emits green, and a blue sub-pixel that emits blue, but the present invention is not limited thereto.

The timing controller 140 supplies various control signals DCS and GCS and image data RGB to the data driver 120 and the gate driver 130 to control the data driver 120 and the gate driver 130 .

The timing control unit 140 starts scanning in accordance with the timing to be implemented in each frame based on the timing signal TS received from the main control unit 1010. [ The timing controller 140 converts the video signal VS received from the main controller 1010 into a data signal format that can be processed by the data driver 120 and outputs the video data RGB. Thus, the timing controller 140 controls the data driving at a proper time according to the scan.

 The timing controller 140 generates various signals including a vertical synchronizing signal Vsync, a vertical synchronizing signal Hsync, a data enable signal DE, a data clock signal DCLK, And receives the timing signals TS from the main control unit 1010.

The timing controller 140 controls the data driver 120 and the gate driver 130 by using a vertical synchronization signal Vsync, a vertical synchronization signal Hsync, a data enable signal DE, a data clock signal DCLK, And outputs various control signals DCS and GCS to the data driver 120 and the gate driver 130,

For example, in order to control the gate driver 130, the timing controller 140 may include a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable signal (GCS) including a gate enable signal (GCS), enable signal (GOE), and the like.

Here, the gate start pulse controls the operation start timing of one or more gate circuits constituting the gate driver 130. The gate shift clock is a clock signal commonly input to one or more gate circuits, and controls the shift timing of the scan signal (gate pulse). The gate output enable signal specifies timing information of one or more gate circuits.

In addition, the timing controller 140 may include a source start pulse (SSP), a source sampling clock (SSC), and a source output enable signal (Souce Output Enable) to control the data driver 120. SOE), and the like.

Here, the source start pulse controls the data sampling start timing of one or more data circuits constituting the data driver 120. The source sampling clock is a clock signal that controls the sampling timing of data in each data circuit. The source output enable signal controls the output timing of the data driver 120.

The timing controller 140 controls the timing controller 140 to control the connection of the source printed circuit board to which the data driver 120 is connected through a connection medium such as a flexible flat cable (FFC) or a flexible printed circuit (FPC) And may be disposed on a printed circuit board (Control Printed Circuit Board).

The control PCB may further include a power controller for controlling various voltages or currents to supply or supply various voltages or currents to the display panel 110, the data driver 120, the gate driver 130, and the like. The power control unit may be referred to as a power management IC (PMIC).

The source printed circuit board and the control printed circuit board described above may be constituted by one printed circuit board.

The gate driver 130 sequentially supplies the gate voltages of the on voltage or the off voltage to the gate lines GL1 to GLm under the control of the timing controller 140. [

The gate driver 130 may be located on only one side of the display panel 110, or may be located on both sides of the display panel 110, depending on the driving method.

The gate driver 130 may be connected to a bonding pad of the display panel 110 by a Tape Automated Bonding (TAB) method or a chip on glass (COG) In Panel type, and may be directly disposed on the display panel 110, and may be integrated and disposed on the display panel 110, as the case may be.

The gate driver 130 may include a shift register, a level shifter, and the like.

The data driver 120 converts the image data RGB received from the timing controller 140 into analog data voltages and outputs them to the data lines DL1 to DLn.

The data driver 120 may be connected to the bonding pad of the display panel 110 by a tape automation bonding method or a chip on glass method or may be directly disposed on the display panel 110, As shown in FIG.

In addition, the data driver 120 may be implemented by a chip on film (COF) method. In this case, one end of the data driver 120 may be bonded to at least one source printed circuit board, and the other end may be bonded to the display panel 110.

The data driver 120 may include a logic unit including various circuits such as a level shifter and a latch unit, a digital analog converter (DAC), an output buffer, and the like.

3 is a circuit diagram for explaining driving of pixels arranged in a display device provided in a videowall apparatus according to an embodiment of the present invention.

The driving of each pixel Px will be described with reference to FIG. First, the switching transistor ST is turned on by the gate voltage supplied to the gate lines GL1 to GLm of each pixel Px. The data voltage Vdata is supplied from the data lines DL1 to DLn by the turn-on switching transistor ST and the driving current i is supplied to the driving transistor DT by the driving transistor DT. Respectively. Finally, the organic light emitting diode OLED displays an image by emitting light corresponding to the controlled driving current i.

4 is a schematic block diagram for explaining a main control unit included in a videowall apparatus according to an embodiment of the present invention.

4, the main control unit 1010 includes an image average level calculating unit 1011, a peak luminance controlling unit 1013, a Gaussian curve setting unit 1015, and a gain determining unit 1017.

The image average level calculating unit 1011 calculates an average picture level (APL) representing the average gradation of the divided images output to the respective display panels 110 to 910.

Here, the image average level APL means an average gradation percentage value of the pixels Px of the display panels 110 to 910 in one frame. Specifically, each pixel Px may include a red sub-pixel that emits red, a green sub-pixel that emits green, and a blue sub-pixel that emits blue, so that the image average level (APL) , The gradation of the green sub-pixel, and the gradation of the blue sub-pixel.

The calculation method of the image average level (APL) may be different according to the detailed setting of the image average level (APL).

[Equation 1]

Here, R denotes the gray level of the red sub-pixel, B denotes the gray level of the green sub-pixel, B denotes the gray level of the blue sub-pixel, and γ denotes the gamma value of the display panel 110 to 910, have.

According to Equation (1), it can be seen that the image average level (APL) is determined by the gray level of the red sub-pixel, the gray level of the green sub-pixel and the gray level of the blue sub-pixel .

5 is a graph illustrating an operation of a peak luminance controller included in a videowall apparatus according to an exemplary embodiment of the present invention.

Next, the peak luminance controller 1013 controls the peak luminance (PL) of the display panels 110 to 910 based on the image average level APL.

Here, the peak luminance PL of the display panels 110 to 910 refers to the maximum luminance among the luminance of the display panels 110 to 910. That is, the peak luminance PL may mean the luminance at the center of the display panels 110 to 910, but it is not limited to this and means the maximum luminance at all positions of the display panels 110 to 910.

The peak luminance PL can be reduced as the image average level APL is higher. The method of controlling the peak luminance PL may be different for each setting of the display panel 110 to 910. For example, the control method of the peak luminance PL may be described by the following equation (2).

&Quot; (2) "

5, when the image average level APL is 25% or more, the peak luminance PL can be controlled to decrease relatively rapidly. When the image average level APL is 25% or less, So that the peak luminance PL can be controlled to be gradually decreased.

In the case of an image with a low image average level APL, it is possible to realize the display panels 110 to 910 of high luminance by increasing the peak luminance PL. In the case of an image with a high image average level APL, PL) can be lowered and power consumption can be reduced.

6 is a graph illustrating the brightness of a display panel included in a videowall apparatus according to an exemplary embodiment of the present invention.

The Gaussian curve setting unit 1015 sets the luminance of each of the display panels 110 to 910 to follow the Gaussian curve based on the calculated image average level APL.

The reason why the luminance of the display panels 110 to 910 follows the Gaussian curve is that when the luminance of the central portion of the display panels 110 to 910 is set to be the peak luminance PL, Is set by the Gaussian function described in Equation (3).

&Quot; (3) "

Here, x denotes a position in a first axial direction, y denotes a position in a second axial direction perpendicular to the first axial direction, and G denotes a gain of a luminance to be described later. Here, the Gaussian curve setting unit 1015 sets the gain to 1 and sets the Gaussian curve. In general, since the display panels 110 to 910 are two-dimensional, a Gaussian curve is set for the first axis and the second axis, respectively. Hereinafter, for convenience of explanation, the first axis will be described.

Referring to FIG. 6, the luminance along the Gaussian curve is set symmetrically about the center of the display panels 110 to 910. Since the first sigma value sigma 1 is smaller than the second sigma sigma 2, the curvature of the first Gaussian curve Gaussian 1 due to the first sigma sigma 1 becomes the second sigma sigma sigma < Is larger than the curvature of the curve (Gaussian 2). That is, as the sigma value increases, the curvature of the Gaussian curve decreases.

As the curvature of the Gaussian curve decreases, the total luminance of the display panels 110 to 910 to which the Gaussian curve is applied is relatively high. Specifically, assuming that the percentage value of the total luminance of the display panels 110 to 910 to which the Gaussian curve is not applied is 100%, the total luminance of the display panels 110 to 910 to which the first Gaussian curve Gaussian 1 is applied , The percentage value of the total luminance of the display panels 110 to 910 to which the second Gaussian curve 2 is applied is 65%.

Based on this, the Gaussian curve setting unit 1015 sets the Gaussian curve such that the higher the calculated image average level APL, the higher the percentage of the total brightness of the display panels 110 to 910. In other words, the Gaussian curve setting unit 1015 sets the curvature of the Gaussian curve to decrease as the calculated image average level APL increases.

Then, the sigma values (? _X ,? _Y ) according to the set Gaussian curve are determined through Equation (4).

&Quot; (4) "

For example, the percentage value of the total luminance of the display panels 110 to 910 to which the Gaussian curve set by the Gaussian curve setting unit 1015 is applied according to the image average level APL and the corresponding sigma values are shown in Table 1.

[Table 1]

In summary, the peak luminance PL is decreased by the peak luminance controller 1013 as the image average level APL is higher, but when the Gaussian curve setting unit 1015 sets the luminance of the entire display panels 110 to 910 to which the Gaussian curve is applied Increase the percentage value of. On the contrary, the peak luminance PL is increased by the peak luminance controller 1013 as the image average level APL is lower, and the Gaussian curve setting unit 1015 sets the peak luminance PL of the entire luminance of the display panels 110 to 910 to which the Gaussian curve is applied. Decrease the percentage value.

Therefore, the peak luminance control unit 1013 and the Gaussian curve setting unit 1015 adjust the peak luminance PL and the luminance of the entire display panels 110 to 910, It is possible to reduce the difference in total luminance between the plurality of display panels 110 to 910 even if there is a large difference in the APL. Thus, the difference in total luminance of each display panel 110 to 910 is reduced below the perception level of the viewer, so that the image quality of the entire image of the video wall apparatus 1000 can be improved.

FIG. 7 is a schematic block diagram illustrating a gain determiner included in a videowall apparatus according to an exemplary embodiment of the present invention. Referring to FIG.

7, the gain determining unit 1017 includes a region of interest setting unit 1017a, a complexity calculating unit 1017b, a consumed current value calculating unit 1017c, and a gain setting unit 1017d.

As described above, the gain is set to 1 in the Gaussian curve setting unit 1015 and the Gaussian curve is set. The gain determiner 1017 compares the ROI, the image complexity (IC), and the current consumption (CC) of each of the display panels 110 to 910 with a comprehensive , The gain set to 1 is determined as a specific value.

The ROI setting unit 1017a sets a ROI in each video wall apparatus 1000. Here, the term ROI may refer to a segmented image that should be emphasized according to need among the images displayed in the video wall apparatus 1000, and may mean a segmented image that varies according to the viewer's position.

Accordingly, the ROI setting unit 1017a may store information of the display panels 110 to 910 in which ROIs are previously set, track ROIs of the ROIs, Information of the display panels 110 to 910 can be grasped.

8 is a view showing a plurality of display areas arranged on a display panel provided in a videowall apparatus according to an embodiment of the present invention.

The complexity calculator 1017b analyzes the images output from the display panels 110 to 910 and analyzes the complexity (IC) of each image.

Here, the complexity (IC) of the image is an index indicating how complex the image outputted from the display panel 110 to 910 is. This can be interpreted in various meanings according to the setting, but may mean a difference in gradation between adjacent display areas PA in one display panel 110 to 910, for example.

8, the display panels 110 to 910 include display areas PA (1,1) arranged in the first row and the first column, display areas (PA (1,1)) arranged in the pth row and the qth row PA (p, q)). Here, the grayscale of the display area PA (2,2) arranged in the second row and the second column and the grayscale of the display area PA (2, 2) arranged in the second row and the second column, (IC) of the image by averaging the differences between the gradations of the PA (1, 1) to PA (3, 3) and converting it into a percentage value. That is, the complexity (IC) of the image of the display area PA (2,2) arranged in the second row and the second column can be calculated by setting both i and j to 2 according to Equation (5).

&Quot; (5) "

Here, g denotes the gradation of the display area, and 1/8 denotes the average of the gradation differences between the center display area and the adjacent display area.

Next, the consumed current value calculation unit 1017c calculates the consumption current value CC in each of the display panels 110 to 910 based on the average luminance value of the display panels 110 to 910. [

More specifically, the consumption current value CC of the display panels 110 to 910 is the sum of the consumption current values CC of the plurality of pixels Px of the display panels 110 to 910. The consumed current value CC of each pixel Px can be calculated through Equation (6).

&Quot; (6) "

Here, the pixel current consumption means the consumption current value CC of each pixel Px, the Average Luminance means the average luminance of the display panels 110 to 910, the efficiency is the efficiency of the organic light emitting diode OLED And Transmissivity means the polarizer transmittance.

Then, the consumption current value CC of the display panel 110 to 910 is calculated by summing up the consumed current values CC in the pixel Px thus calculated.

The gain setting unit 1017d sets the gains of the display panels 110 to 910 on the basis of the set ROI, the calculated complexity IC of the image, and the consumption current value CC of the display panels 110 to 910, The gain of the entire luminance is determined.

The gain setting unit 1017d increases the gain of the brightness of the display panel 110 to 910 corresponding to the set ROI. Specifically, the gain setting unit 1017d sets the gain of the entire brightness of the display panels 110 to 910 corresponding to the set ROI to 1 or more, and adjusts the total brightness of the other display panels 110 to 910 Can be set to be equal to or less than 1 so that the divided image output to the ROI can be highlighted.

The gain setting unit 1017d increases the gain of the brightness of the display panels 110 to 910 as the calculated complexity IC of the image is lower. In the case of a simple image due to a low complexity (IC) of the image, it is highly likely that the luminance reduction of the outer portion of the display panels 110 to 910 due to the Gaussian curve is recognized. Therefore, when the complexity (IC) of the image is low, it is possible to increase the gain of the luminance and to prevent the luminance difference of the outer portion of the display panels 110 to 910 from being recognized. For example, the gain may be set to 1.2 when the complexity (IC) of the image is equal to or higher than the threshold value, but the present invention is not limited thereto.

Finally, the gain setting unit 1017d increases the maximum current consumption value (Max current) among the consumption current values CC of the display panels 110 to 910 to the allowable current value (Current limit) of the display panels 110 to 910 The gain of the entire luminance of the display panels 110 to 910 can be increased.

That is, the consumption current value CC of each of the display panels 110 to 910 is set to be larger than the maximum current consumption value CC of the current consumption value CC of each of the display panels 110 to 910 (Max current) times) to increase the gain of the luminance.

Specifically, the consumption current value (CC) of the display panels 110 to 910 and the consumption current value (Gained CC) thereof are shown in Table 2. According to Table 2, the consumption current of the fourth display panel 410 corresponds to the maximum current consumption value of 6.9 A, and the current limit of the display panels 110 to 910 is 7.2 . Therefore, the consumption current value CC of each of the entire display panels 110 to 910 is increased by (the allowable current value (7.2 A) / the maximum current consumption value (6.9 A)) times. That is, the consumption current value CC of each of the entire display panels 110 to 910 is increased by 1.04 times. Therefore, the consumed current value Gained CC of the fourth display panel 410 is increased to 7.2 A, which is the allowable current value, and the consumed current value Gained CC of the other display panels 110 to 910 is also increased.

[Table 2]

Accordingly, the consumption current value Gained CC of all the display panels 110 to 910 increases, and the gain of the luminance of all the display panels 110 to 910 also increases, thereby increasing the luminance of the entire video wall apparatus 1000 It is effective.

The video wall apparatus 1000 according to an embodiment of the present invention adjusts the peak luminance PL and the total luminance of the display panels 110 to 910 so that the image average level APL), it is possible to reduce the difference in total luminance between the plurality of display panels 110 to 910. [ Thus, the difference in total luminance of each display panel 110 to 910 is reduced below the perception level of the viewer, so that the image quality of the entire image of the video wall apparatus 1000 can be improved.

In addition, the video wall apparatus 1000 according to an embodiment of the present invention comprehensively considers the ROI, the complexity IC of the image, and the consumption current value CC of each of the display panels 110 to 910 Thereby increasing the luminance of the entire display panels 110 to 910 and increasing the luminance of the video wall apparatus 1000 as a whole.

Hereinafter, a method of driving a videowall apparatus according to an embodiment of the present invention will be described in detail with reference to Figs.

9 is a flowchart illustrating a method of driving a videowall apparatus according to an embodiment of the present invention.

9, the driving method (S100) of the video wall apparatus includes the steps of calculating an image average level (S110), a peak luminance control step S120, a Gaussian curve setting step S130 and a gain determination step S140 .

In the image average level calculating step S110, an average picture level (APL) representing the average gradation of the divided images output to each of the display panels 110 to 910 is calculated.

Here, the image average level APL means an average gradation percentage value of the pixels Px of the display panels 110 to 910 in one frame. Specifically, each pixel Px may include a red sub-pixel that emits red, a green sub-pixel that emits green, and a blue sub-pixel that emits blue, so that the image average level (APL) , The gradation of the green sub-pixel, and the gradation of the blue sub-pixel.

The calculation method of the image average level (APL) may be different according to the detailed setting of the image average level (APL).

[Equation 1]

Here, R denotes the gray level of the red sub-pixel, B denotes the gray level of the green sub-pixel, B denotes the gray level of the blue sub-pixel, and γ denotes the gamma value of the display panel 110 to 910, have.

According to Equation (1), it can be seen that the image average level (APL) is determined by the gray level of the red sub-pixel, the gray level of the green sub-pixel and the gray level of the blue sub-pixel .

Next, in the peak luminance control step S120, the peak luminance (PL) of the display panels 110 to 910 is controlled based on the image average level APL.

Here, the peak luminance PL of the display panels 110 to 910 refers to the maximum luminance among the luminance of the display panels 110 to 910. That is, the peak luminance PL may mean the luminance at the center of the display panels 110 to 910, but it is not limited to this and means the maximum luminance at all positions of the display panels 110 to 910.

The peak luminance PL can be reduced as the image average level APL is higher. The method of controlling the peak luminance PL may be different for each setting of the display panel 110 to 910. For example, the control method of the peak luminance PL may be described by the following equation (2).

&Quot; (2) "

5, when the image average level APL is 25% or more, the peak luminance PL can be controlled to decrease relatively rapidly. When the image average level APL is 25% or less, So that the peak luminance PL can be controlled to be gradually decreased.

In the case of an image with a low image average level APL, it is possible to realize the display panels 110 to 910 of high luminance by increasing the peak luminance PL. In the case of an image with a high image average level APL, PL) can be lowered and power consumption can be reduced.

In the Gaussian curve setting step S130, the luminance of each of the display panels 110 to 910 is set to follow the Gaussian curve based on the calculated image average level APL.

The reason why the luminance of the display panels 110 to 910 follows the Gaussian curve is that when the luminance of the central portion of the display panels 110 to 910 is set to be the peak luminance PL, Is set by the Gaussian function described in Equation (3).

&Quot; (3) "

Here, x denotes a position in a first axial direction, y denotes a position in a second axial direction perpendicular to the first axial direction, and G denotes a gain of a luminance to be described later. Here, the Gaussian curve setting step (S130) sets the gain to 1 and sets the Gaussian curve. In general, since the display panels 110 to 910 are two-dimensional, a Gaussian curve is set for the first axis and the second axis, respectively. Hereinafter, for convenience of explanation, the first axis will be described.

Referring to FIG. 6, the luminance along the Gaussian curve is set symmetrically about the center of the display panels 110 to 910. Since the first sigma value sigma 1 is smaller than the second sigma sigma 2, the curvature of the first Gaussian curve Gaussian 1 due to the first sigma sigma 1 becomes the second sigma sigma sigma < Is larger than the curvature of the curve (Gaussian 2). That is, as the sigma value increases, the curvature of the Gaussian curve decreases.

As the curvature of the Gaussian curve decreases, the total luminance of the display panels 110 to 910 to which the Gaussian curve is applied is relatively high. Specifically, assuming that the percentage value of the total luminance of the display panels 110 to 910 to which the Gaussian curve is not applied is 100%, the total luminance of the display panels 110 to 910 to which the first Gaussian curve Gaussian 1 is applied , The percentage value of the total luminance of the display panels 110 to 910 to which the second Gaussian curve 2 is applied is 65%.

Based on this description, the Gaussian curve setting step S130 sets the Gaussian curve such that the higher the calculated image average level APL is, the higher the percentage value of the total brightness of the display panels 110 to 910 is. In other words, the Gaussian curve setting step S130 sets the curvature of the Gaussian curve to decrease as the calculated image average level APL increases.

Then, the sigma values (? _X ,? _Y ) according to the set Gaussian curve are determined through Equation (4).

&Quot; (4) "

For example, the percentage values of the total brightness of the display panels 110 to 910 to which the Gaussian curve set in the Gaussian curve setting step S130 according to the image average level APL and the corresponding sigma values are shown in Table 1.

[Table 1]

In summary, the peak luminance PL is decreased by the peak luminance control step S120 as the image average level APL is higher, but in the Gaussian curve setting step S130, the entire display panels 110 to 910 to which the Gaussian curve is applied Increase the percentage value of luminance. On the other hand, as the image average level APL is lower, the peak luminance PL is increased by the peak luminance control step S120, but the luminance of the entire display panels 110 to 910 to which the Gaussian curve is applied in the Gaussian curve setting step S130 Lt; / RTI >

Accordingly, in the peak luminance control step S120 and the Gaussian curve setting step S130, the peak luminance PL and the luminance of the whole display panels 110 to 910 are adjusted to adjust the average of the images among the plurality of display panels 110 to 910 The difference in total luminance between the plurality of display panels 110 to 910 can be reduced even if there is a large difference in the level APL. Thus, the difference in total luminance of each display panel 110 to 910 is reduced below the perception level of the viewer, so that the image quality of the entire image of the video wall apparatus 1000 can be improved.

10 is a flow chart for explaining gain determination steps of a method of driving a videowall apparatus according to an embodiment of the present invention.

10, the gain determination step S140 includes a region of interest setting step S141, a complexity calculating step S142, a consumed current value calculating step S143, and a gain setting step S144.

As described above, in the Gaussian curve setting step (S130), the gain is set to 1 and the Gaussian curve is set. In the gain determination step S140, the ROI, the image complexity IC, and the current consumption (CC) of each of the display panels 110 to 910 are integrated , The gain set to 1 is determined as a specific value.

In the ROI setting step S141, a ROI is set in each video wall apparatus 1000. Here, the term ROI may refer to a segmented image that should be emphasized according to need among the images displayed in the video wall apparatus 1000, and may mean a segmented image that varies according to the viewer's position.

Accordingly, in the ROI setting step S141, the information on the display panels 110 to 910 on which the ROIs are previously set are stored or the ROIs are arranged in real time by tracking the positions of the viewers Information of the display panels 110 to 910 can be grasped.

Next, in the complexity calculating step S142, the images output from the respective display panels 110 to 910 are analyzed, and the complexity (IC) of each image is analyzed.

Here, the complexity (IC) of the image is an index indicating how complex the image outputted from the display panel 110 to 910 is. This can be interpreted in various meanings according to the setting, but may mean a difference in gradation between adjacent display areas PA in one display panel 110 to 910, for example.

8, the display panels 110 to 910 include display areas PA (1,1) arranged in the first row and the first column, display areas (PA (1,1)) arranged in the pth row and the qth row PA (p, q)). Here, the grayscale of the display area PA (2,2) arranged in the second row and the second column and the grayscale of the display area PA (2, 2) arranged in the second row and the second column, (IC) of the image by averaging the differences between the gradations of the PA (1, 1) to PA (3, 3) and converting it into a percentage value. That is, the complexity (IC) of the image of the display area PA (2,2) arranged in the second row and the second column can be calculated by setting both i and j to 2 according to Equation (5).

&Quot; (5) "

Here, g denotes the gradation of the display area, and 1/8 denotes the average of the gradation differences between the center display area and the adjacent display area.

Next, in the consumption current value calculating step S143, the consumption current value CC in each of the display panels 110 to 910 is calculated based on the average luminance value of the display panels 110 to 910.

More specifically, the consumption current value CC of the display panels 110 to 910 is the sum of the consumption current values CC of the plurality of pixels Px of the display panels 110 to 910. The consumed current value CC of each pixel Px can be calculated through Equation (6).

&Quot; (6) "

Here, the pixel current consumption means the consumption current value CC of each pixel Px, the Average Luminance means the average luminance of the display panels 110 to 910, the efficiency is the efficiency of the organic light emitting diode OLED And Transmissivity means the polarizer transmittance.

Then, the consumption current value CC of the display panel 110 to 910 is calculated by summing up the consumed current values CC in the pixel Px thus calculated.

In the gain setting step S144, based on the set ROI, the calculated complexity IC of the image, and the consumption current value CC of the display panels 110 to 910, the display panels 110 to 910, The gain of the entire luminance is determined.

In the gain setting step S144, the gain of the luminance of the display panels 110 to 910 corresponding to the set ROI is increased. Specifically, in the gain setting step S144, the gain of the entire luminance of the display panels 110 to 910 corresponding to the set ROI is set to 1 or more, and the total luminance of the other display panels 110 to 910 Can be set to be equal to or less than 1 so that the divided image output to the ROI can be highlighted.

In the gain setting step S144, as the calculated complexity IC of the image is lower, the gain of the brightness of the display panels 110 to 910 is increased. In the case of a simple image due to a low complexity (IC) of the image, it is highly likely that the luminance reduction of the outer portion of the display panels 110 to 910 due to the Gaussian curve is recognized. Therefore, when the complexity (IC) of the image is low, it is possible to increase the gain of the luminance and to prevent the luminance difference of the outer portion of the display panels 110 to 910 from being recognized. For example, the gain may be set to 1.2 when the complexity (IC) of the image is equal to or higher than the threshold value, but the present invention is not limited thereto.

Lastly, in the gain setting step S144, the maximum current consumption value CC among the consumption current values CC of the display panels 110 to 910 is increased to the allowable current value (current limit) of the display panels 110 to 910 The gain of the entire luminance of the display panels 110 to 910 can be increased.

That is, the consumption current value CC of each of the display panels 110 to 910 is set to be larger than the maximum current consumption value CC of the current consumption value CC of each of the display panels 110 to 910 (Max current) times) to increase the gain of the luminance.

Specifically, the consumption current value (CC) of the display panels 110 to 910 and the consumption current value (Gained CC) thereof are shown in Table 2. According to Table 2, the consumption current of the fourth display panel 410 corresponds to the maximum current consumption value of 6.9 A, and the current limit of the display panels 110 to 910 is 7.2 . Therefore, the consumption current value CC of each of the entire display panels 110 to 910 is increased by (the allowable current value (7.2 A) / the maximum current consumption value (6.9 A)) times. That is, the consumption current value CC of each of the entire display panels 110 to 910 is increased by 1.04 times. Therefore, the consumed current value Gained CC of the fourth display panel 410 is increased to 7.2 A, which is the allowable current value, and the consumed current value Gained CC of the other display panels 110 to 910 is also increased.

[Table 2]

Accordingly, the consumption current value Gained CC of all the display panels 110 to 910 increases, and the gain of the luminance of all the display panels 110 to 910 also increases, thereby increasing the luminance of the entire video wall apparatus 1000 It is effective.

As a result, in the method (S100) for driving a videowall apparatus according to an embodiment of the present invention, the peak luminance PL and the total luminance of the display panels 110 to 910 are adjusted to provide a video The difference in total luminance between the plurality of display panels 110 to 910 can be reduced even if there is a large difference in the average level APL. Thus, the difference in total luminance of each display panel 110 to 910 is reduced below the perception level of the viewer, so that the image quality of the entire image of the video wall apparatus 1000 can be improved.

In addition, the driving method (SlOO) of the video wall apparatus according to the embodiment of the present invention may further include a method of driving the video wall apparatus using the ROI, the image complexity IC and the consumption current value CC of each of the display panels 110 to 910 There is an effect that the luminance of the entire display panel 110 to 910 is increased to increase the luminance of the video wall apparatus 1000 as a whole.

Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those embodiments and various changes and modifications may be made without departing from the scope of the present invention. . Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

1000: Video wall device
1010:
1011: image average level calculating unit
1013: Peak luminance controller
1015: Gaussian curve setting unit
1017: gain determining unit
1017a: Interest area setting unit
1017b: Complexity calculation unit
1017c: consumption current value calculating section
1017d: gain setting unit

Claims (15)

A plurality of display devices and
And a main controller for outputting video signals to the plurality of display devices,
The main control unit,
An image average level calculating unit for calculating an image average level of an image output from the display panel of each display device;
A peak luminance control unit for controlling a peak luminance of each of the display panels based on the image average level;
A Gaussian curve setting unit for setting the luminance of each of the display panels according to the Gaussian curve based on the image average level,
And a gain determination unit that determines a gain of a luminance of each of the display panels. The method according to claim 1,
The peak luminance controller
And decreases the peak luminance as the image average level is higher. The method according to claim 1,
Wherein the Gaussian curve setting unit comprises:
And sets the Gaussian curve so that the luminance at the center portion of the display panel becomes the peak luminance. The method according to claim 1,
The Gaussian curve setting unit
And reduces the curvature of the Gaussian curve as the image average level increases. The method according to claim 1,
The gain determiner
A region of interest setting unit for setting a region of interest in the video wall apparatus;
A complexity calculation unit for calculating a complexity of an image output from each of the display panels;
A consumed current value calculating unit for calculating a consumed current value of each of the display panels; And
And a gain setting unit for setting a gain of luminance of each of the display panels based on the set area of interest, the complexity of the image, and the consumption current value. 6. The method of claim 5,
The gain setting unit
And increases the gain of the luminance as the complexity of the image is lower. 6. The method of claim 5,
The gain setting unit
And increases the gain of the luminance of the display panel corresponding to the set region of interest. 6. The method of claim 5,
The gain setting unit
Wherein the consumption current of each of the display panels is increased by a value of (allowable current value / maximum consumed current value among consumption current values of the respective display panels) to increase the gain of the luminance. A method of driving a videowall apparatus having a plurality of display panels,
An image average level calculating step of calculating an image average level of an image outputted from each display panel;
A peak luminance control step of controlling a peak luminance of each of the display panels based on the image average level;
A Gaussian curve setting step of setting, based on the image average level, the luminance of each of the display panels to follow the Gaussian curve; and
And a gain determining step of determining a gain of a luminance of each of the display panels. 10. The method of claim 9,
In the peak luminance control step
And decreases the peak luminance as the image average level becomes higher. 10. The method of claim 9,
In the Gaussian curve setting step
And decreasing the curvature of the Gaussian curve as the image average level is higher. 10. The method of claim 9,
The gain determining step
Establishing a region of interest in the videowall apparatus;
A complexity calculating step of calculating a complexity of an image output from each of the display panels;
A consumed current value calculating step of calculating a consumed current value of each of the display panels;
And a gain setting step of setting a gain of luminance of each of the display panels based on the set area of interest, the complexity of the image, and the consumption current value. 13. The method of claim 12,
In the gain setting step
Wherein the gain of the luminance is increased as the complexity of the image is lower. 13. The method of claim 12,
In the gain setting step
Wherein the gain of the luminance of the display panel corresponding to the set region of interest is increased. 13. The method of claim 12,
In the gain setting step
Wherein the consumption current of each of the display panels is increased by an allowable current value / a maximum consumption current value of consumption current values of the respective display panels to increase the gain of the luminance.

Images