KR20210047508A - Display appratus and controlling method thereof - Google Patents

Abstract

The present invention provides a display apparatus and a control method thereof, which secure visibility. According to one embodiment of the present invention, the display apparatus comprises: a storage part which stores a preset brightness target value; and a plurality of display modules including a liquid crystal panel, a backlight unit, and a control part which controls the liquid crystal panel and the backlight unit. A first display module receives an image signal including a plurality of frames, and predicts the brightness of a frame area corresponding to the first display module. The control part controls the backlight unit based on the difference between the predicted brightness and the brightness target value. A second display module receives the image signal transferred by the first display module, and predicts the brightness of a frame area corresponding to the second display module. The control part controls the backlight unit based on the difference between the predicted brightness and the target brightness value.

Description

Display device and control method of the display device {DISPLAY APPRATUS AND CONTROLLING METHOD THEREOF}

The disclosed embodiment relates to a signage device including a plurality of display modules.

Signage refers to a service that displays various information such as text and video on a display screen in public or commercial spaces, and is used for advertising or publicity purposes.

The signage device is an example of a display device that provides various contents, and may operate in a form of transmitting an image signal such as a video or image to a set-top box through a wired or wireless network and outputting it to a screen. Most of these signage devices are provided in a large size so that a plurality of display modules are combined and displayed to the public.

Meanwhile, in the local dimming backlight technology, the amount of light is controlled to increase the contrast ratio of the display device, and the amount of light is adjusted by dividing the display device into each area. This local dimming backlight technology can be applied to a signage device.

When each display device applies a local dimming backlight technology in a video wall in which a plurality of display modules are combined, the display module included in the video wall device corresponds to the contrast of the frame area input for each display. Adjusts the amount of light for each area of the display. However, when the same object is placed between adjacent display modules, for example, when an image with bright gray objects on a very dark gray background is input to the video wall, the position of the bright gray object spans between the display modules. There is a problem in that a difference in luminance between adjacent display modules occurs due to a difference in the number of light-emitting LEDs when the ratios occupied by the bright gray-scale objects in the frame area corresponding to are different.

According to one disclosed aspect, a display device and a method of controlling the display device for securing visibility by adjusting the luminance to a target luminance value by each display module displaying an image signal are provided.

The display device according to the disclosed embodiment includes: a storage unit for storing a preset luminance target value; And a plurality of display modules including a liquid crystal panel, a backlight unit, and a control unit for controlling the liquid crystal panel and the backlight unit, wherein the first display module receives an image signal including a plurality of frames, and the Predicting the luminance of a frame region corresponding to the first display module, the control unit controlling the backlight unit based on the difference between the predicted luminance and the luminance target value, and the second display module, the first display Receiving the image signal transmitted from the module, predicting the luminance of a frame region corresponding to the second display module, and the control unit controlling the backlight unit based on a difference between the predicted luminance and the target luminance value can do.

The first display module and the second display module calculate a difference between the predicted luminance and the target luminance value as a duty ratio based on the predicted luminance and a preset reference value, and based on the calculated duty ratio, the The controller may control the backlight unit.

The first display module and the second display module may predict luminance based on an average picture level (APL).

The first and second display modules may predict luminance based on a histogram distribution of an image.

The backlight circuit may include a light source including a plurality of light emitting diodes; And a light guide plate for diffusing light emitted by a light source therein and emitting the light to the liquid crystal panel.

And an input unit for receiving a user input, and the target luminance value may be changed by the input.

The first display module controls the backlight unit so that the luminance of a preset number of frames among the plurality of frames is not visually recognized based on an APL or a histogram distribution diagram, and the second display module, The backlight unit may be controlled so that the luminance of the frames transmitted by the first display module of a preset number is not visually recognized.

According to another disclosed embodiment, a method for controlling a display device including a plurality of display modules includes storing a preset luminance target value; Predicting the luminance of the frame area corresponding to the first display module; A first display module displays the frame area based on a difference between the predicted luminance and the luminance target value; A second display module receiving the image signal transmitted from the first display module; Predicting the luminance of a frame area corresponding to the second display module; And displaying the frame area by the second display module based on the difference between the predicted luminance and the target luminance value.

Predicting luminance by the first display module and the second display module includes calculating a difference between the predicted luminance and the target luminance value as a duty ratio based on the predicted luminance and a preset reference value; I can.

Displaying the frame area by the first display module and the second display module may include controlling a backlight unit based on the calculated duty ratio.

Predicting luminance by the first and second display modules may include estimating luminance based on an average picture level (APL).

Predicting luminance by the first and second display modules may include estimating luminance based on a histogram distribution of an image.

Receiving a user's input; may further include, and the preset luminance target value may include being changed by the user's input.

Predicting the luminance of a frame region corresponding to the first display module includes: predicting a change in luminance in a preset number of frames among the plurality of frames by a preset number of first display modules, and the Displaying the frame area by the first display module may include controlling the backlight unit so that the change in luminance is not visually recognized.

Predicting the luminance of the frame region corresponding to the second display module includes: predicting, by the second display module, a change in luminance in the preset number of frames based on an APL or a histogram distribution map, and the second display module. 2 Displaying the frame area by the display module may include controlling the backlight unit so that the change in luminance is not visually recognized.

In the display device and the method for controlling the display device according to the disclosed aspect, visibility may be secured by adjusting the luminance to a target luminance value by each display module displaying an image signal.

1 is a diagram illustrating an appearance of a display device according to an exemplary embodiment.
2 is a control block diagram of a display device.
3 and 4 are diagrams for explaining a difference in luminance measured when one display module displays different image signals.
5 is a diagram showing an image in which a luminance level difference can be visually recognized.
6 is a diagram illustrating an image displayed by a display device in which luminance is adjusted according to an exemplary embodiment.
7 is a flowchart illustrating a method of controlling a display device according to an exemplary embodiment.
8 is a flowchart illustrating a method of controlling a display device according to another exemplary embodiment.

The same reference numerals refer to the same elements throughout the specification. This specification does not describe all elements of the embodiments, and general content in the technical field to which the present invention belongs or overlapping content between the embodiments will be omitted. The term'unit, module, member, block' used in the specification may be implemented in software or hardware, and according to embodiments, a plurality of'units, modules, members, blocks' may be implemented as one component, It is also possible for one'unit, module, member, block' to include a plurality of components.

Throughout the specification, when a part is said to be "connected" with another part, this includes not only the case of being directly connected, but also the case of indirect connection, and the indirect connection includes connection through a wireless communication network. do.

In addition, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

Throughout the specification, when a member is said to be positioned "on" another member, this includes not only the case where the member is in contact with the other member, but also the case where another member exists between the two members.

Terms such as first and second are used to distinguish one component from other components, and the component is not limited by the above-described terms.

Singular expressions include plural expressions, unless the context clearly makes exceptions.

In each step, the identification code is used for convenience of explanation, and the identification code does not describe the order of each step, and each step may be performed differently from the specified order unless a specific order is clearly stated in the context. have.

Hereinafter, the operating principle and embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a diagram illustrating an appearance of a display device according to an exemplary embodiment.

The display device 1 is a device capable of processing an image signal received from the outside and visually displaying the processed image. Hereinafter, a large format display (LFD) in which the display device 1 receives an image signal through the source device 2 and displays the image signal is exemplified, but is not limited thereto. For example, the display device 1 may be implemented with digital signage or digital information display (DID).

The display device 1 may receive a video signal and an audio signal from the source device 2 and output video and audio corresponding to the video signal and the audio signal. In addition, the display device 1 may receive television broadcast content through a broadcast reception antenna or a wired cable, receive content from a content playback device, or receive content from a content providing source of a content provider.

The display device 1 includes a plurality of display modules 10, 11, 12, 13. The display device 1 recognizes the plurality of display modules 10, 11, 12, and 13 as one screen and displays one video wall image. Specifically, when an image signal composed of a plurality of frames is received from the source device 2, the display device 1 displays a single frame image divided to correspond to the display modules 10, 11, 12, 13 do.

As shown in FIG. 1, the display device 1 may include display modules 10, 11, 12, and 13 arranged in a 2x2 matrix. The first display module 10 is at the upper left of the screen S, the second display module 11 is at the upper right of the screen S, and the third display module 12 is at the lower left of the screen S. , The fourth display module 13 may be disposed at the lower right of the screen S.

Here, the expressions of ordinal numbers such as the first and second are used to distinguish the plurality of display modules 100 from each other, and the display module connected to the source device 2 must be referred to as the first display module 10 However, it is not necessary to use ordinal numbers in the order in which the content signals are transmitted.

The display device 1 is not necessarily limited to being provided with four display modules, and the number of display modules and the arrangement form of the 2x2 matrix may be variously changed.

The display modules 10, 11, 12, and 13 may include a body forming an exterior and a component for displaying an image signal inside the body. The front of the display modules 10, 11, 12, and 13 is a part of the screen S, and an image signal may be displayed. A plurality of pixels (P) are formed on the front of the display modules (10, 11, 12, 13), and the image (I) displayed on the screen (S) is formed by a combination of light emitted from the plurality of pixels (P). Can be. For example, a single image may be formed on the screen S by combining light emitted by the plurality of pixels P like a mosaic.

Each of the plurality of pixels P may emit light of various brightnesses and colors.

In order to emit light of various brightness, the plurality of pixels P includes a component capable of directly emitting light (eg, an organic light emitting diode), and can pass or block the light emitted by the backlight unit. It may include a configuration (for example, a liquid crystal panel).

In order to emit light of various colors, each of the plurality of pixels P may include sub-pixels PR, PG, and PB. The sub-pixels PR, PG, and PB include a red sub-pixel PR capable of emitting red light, a green sub-pixel PG capable of emitting green light, and a blue sub-pixel capable of emitting blue light. It may include a pixel PB. For example, red light can represent light with a wavelength of approximately 620nm (nanometer, 1 billionth of a meter) to 750nm, green light can represent light with a wavelength of approximately 495nm to 570nm, and blue light The wavelength can represent light from approximately 450 nm to 495 nm.

Each of the plurality of pixels P emits light of various brightnesses and colors by a combination of the red light of the red sub-pixel PR, the green light of the green sub-pixel PG, and the blue light of the blue sub-pixel PB. can do.

Each of the display modules 10, 11, 12, and 13 may include a liquid crystal panel (LCD panel) and a backlight unit, and a detailed description thereof will be described later in the drawings.

2 is a control block diagram of a display device.

Referring to FIG. 2, in the display device 1, each of the display modules 10, 11, 12, and 13 independently includes a signal processing unit 110, an input unit 120, a storage unit 130, a control unit 140, and The liquid crystal panel 150 includes a backlight unit 160 and a sound output unit 170, respectively.

The first display module 10 receives an image signal from the source device 2.

The signal processing unit 110 can be connected to a set-top box through a plurality of pins and cables, and receives an image signal through an input port. In addition, the signal processing unit 110 distributes an image to be displayed by the first display module 10 and then transmits an image signal to the second display module 11.

In more detail, the signal processing unit 110 progressively divides a transport stream included in a video signal into a video signal, an audio signal, and a sub-stream of additional data. De-interlacing (de-interlacing) transformed by the method, scaling to adjust the resolution of an image signal, noise reduction to improve image quality, detail enhancement, frame refresh rate Image processing such as conversion can be performed. In addition, the signal processing unit 110 divides a region of the frame based on the position and rotation state of the first display module 10 under the control of the controller 140, and separates the first display module 10 to be displayed. Create an image.

The input unit 120 may include a module for receiving a wireless signal by an input button or a remote controller. The input unit 120 receives a user input such as turning on or off of the first display module 10 and a volume and luminance of sound.

The input unit 120 receives an input command transmitted by a user, converts it into an electrical signal, and transmits it to the control unit 140. Specifically, the input unit 120 may receive a user's input for a target luminance value to emit light when the plurality of display modules 10, 11, 12, and 13 display an image from the user. The input unit 120 may convert a user's input for the target luminance value into an electrical signal and transmit it to the control unit 140.

The input unit 120 may be implemented by various input means such as a push switch, a touch switch, a dial, a slide switch, and a toggle switch. Meanwhile, the first display module 10 does not necessarily include the input unit 130. For example, the display device 1 in which the four display modules 10, 11, 12, and 13 are disposed may include an input unit 120 in the fourth display module 13, and receive input from a user and It can be delivered to the display modules 10, 11, and 12.

The storage unit 130 may store programs and/data for processing image data included in the content, and may store temporary data generated while the signal processing unit 110 processes the image signal.

The storage unit 130 may store a target luminance value preset by a manufacturer or a target luminance value input by a user, and provide the target luminance value to the controller 140 to be used for luminance adjustment to be described later.

The storage unit 130 includes a nonvolatile memory such as a ROM (Read Only Memory) and a flash memory for storing data for a long period of time, and a static random access memory (S-RAM) (S-RAM) and D for temporarily storing data. -May include a volatile memory such as a dynamic random access memory (RAM).

Meanwhile, the storage unit 130 may be provided in each of the display modules 10, 11, 12, and 13, but may be provided inside the main body of the display apparatus 1 in an independent configuration.

The liquid crystal panel 150 is provided in front of the backlight unit 160 and blocks or passes light emitted from the backlight unit 160 to form an image.

The front surface of the liquid crystal panel 150 forms the screen S of the first display module 10 and may include a plurality of pixels P. The plurality of pixels P included in the liquid crystal panel 150 may each independently block or pass the light of the backlight unit 160, and the light that has passed through the plurality of pixels P is a screen ( The image I displayed in S) can be formed.

Specifically, the liquid crystal panel 150 may include at least one of a polarizing film, a transparent substrate, a pixel electrode, a thin film transistor, a liquid crystal layer, a common electrode, or a color filter. The configuration of the liquid crystal panel 150 may include a configuration applied to a general display device.

The backlight unit 160 may be divided into a direct-tyep back light unit and an edge-type back light unit according to the position of the light source.

For example, when the backlight unit 160 is an edge type backlight unit, it includes a light guide plate that diffuses light and a light source that emits light. Light is incident on the light guide plate from a light source located on the side of the light guide plate. Light incident on the LGP may move from the side of the LGP to the center through Total Internal Reflection, and uniform surface light may be emitted throughout the LGP by a pattern located on the front or rear of the LGP. have.

In the direct backlight unit, light emitted from a light source may be incident on a diffusion plate provided to improve brightness and uniformity, and uniform surface light may be emitted toward the liquid crystal panel 150 by the diffusion plate.

The backlight unit 160 may perform local dimming control under the control of the controller 140. In the local dimming control, the backlight unit 160 controls the amount of light of a block corresponding to the corresponding area in response to a contrast included in an image signal corresponding to an area of a frame to be displayed by the first display module 10. For example, an area of the backlight unit 160 in which a black image is displayed emits light of low luminance, and an area of the backlight unit 160 in which a white image is displayed is the number of light sources turned on and the amount of light emitted. The luminance can be increased.

The sound output unit 170 includes a sound amplifier that amplifies sound and a speaker that aurally outputs the amplified sound. The speaker may convert the analog sound signal amplified by the sound amplifier into sound (sound wave). For example, the speaker may include a thin film that vibrates according to an electrical sound signal, and a sound wave may be generated by the vibration of the thin film.

Meanwhile, not all of the plurality of display modules 10, 11, 12, and 13 include the sound output unit 170 like the input unit 120. The display apparatus 1 may provide the sound output unit 170 in consideration of the positions and arrangements of a plurality of display modules.

The controller 140 is a processor that oversees the first display module 10. The controller 140 may control each of the above-described components, and may process an image signal and transmit it to the second display module 11.

The controller 140 receives a frame to be displayed from the signal processing unit 110 and generates an individual image to be displayed by the first display module 10 in a single frame. Also, the controller 140 may adjust the luminance of an individual image to be displayed based on the individual image to be displayed by the adjacent display modules 11 and 14 to be close to the target luminance value. The controller 140 controls the liquid crystal panel 140 and the backlight unit 160 to display individual images and determined luminance.

The controller 140 may analyze an image signal of a frame region corresponding to each of the display modules 10, 11, 12, and 13. As a result of image analysis, the controller 140 determines whether an object bright in the frame is displayed on any of the display modules 11, 12, and 13 except for the first display module 10. The controller 140 predicts the luminance to be displayed by the other display modules 11, 12, 13 on which the bright object is displayed, and the backlight unit of the first display module 10 based on the difference between the predicted luminance and the target luminance value. You can also control 160.

A specific method of determining the luminance of an image to be displayed by the controller 140 will be described later with reference to other drawings.

The second display module 11 receives an image signal transmitted from the first display module 10. The controller of the second display module 11 generates an individual image of a frame corresponding to the position of the second display module, and determines the luminance of the individual image so as to approach the target luminance value. The luminance determined by the second display module 11 is determined based on an image to be displayed by the adjacent display modules 10 and 12.

The second display module 11 transmits an image to the third display module 12. The third display module 12 also transmits an image signal to the fourth display module 13 after determining individual images and luminance. In this way, each of the display modules 10, 11, 12, and 13 processes an image corresponding to one frame through a so-called loop-out function.

Meanwhile, the display device 1 is not limited to processing an image by performing a loop-out function. That is, it is sufficient for the display device 1 to adjust the luminance in consideration of an image to be displayed by a display module adjacent to each display module.

In addition to the above-described configuration, the display device 1 may further include various configurations necessary for operation, and each configuration may be changed or deleted. For example, in FIG. 2, the signal processing unit 110 and the control unit 140 are separated for explanation of operations, but are not limited thereto. That is, a physical configuration for processing an image signal and a processor of the controller 140 may be provided as a single chip.

3 and 4 are diagrams for explaining a difference in luminance visually recognized when one display module displays different image signals. In particular, the measurement as shown in FIG. 4 is used when inferring the luminance of the frame area corresponding to the display modules 10, 11, 12, and 13.

Referring first to FIG. 3, the first display module 10 may display a first frame I1 among a plurality of frames included in an image signal. Also, the first display module 10 may display the first frame I1 and then display the second frame I2.

The first frame I1 may include a white patch on a black background. The second frame I2 may include a white patch on a black background. However, the white patch of the first frame I1 may be smaller than the white patch of the second frame I2. That is, the white patch of the first frame I1 may occupy about 10% of the entire screen of the first display module 10. The white patch of the second frame I2 may occupy about 50% of the entire screen of the first display module 10.

In the graph of FIG. 4, the X-axis represents the size occupied by the white patch in %, and the Y-axis represents the luminance (cd/m ² ).

Referring to FIG. 4, as the size of the white patch on the black background increases, the size of the luminance measured by the first display module 10 increases. That is, the more brightly colored objects are included in the frame image, the more light sources of the display module are turned on, so the luminance becomes brighter.

The disclosed display device 1 includes a plurality of display modules 10, 11, 12, and 13, and one frame image is displayed as an individual image corresponding to the display module. Accordingly, the display modules 10, 11, 12, and 13 may divide and display the same object included in one frame, respectively, and even if one frame is displayed, a difference in luminance may occur between adjacent display modules.

Meanwhile, the shape of the graph of FIG. 4 may appear differently depending on the number or position of light sources in the display module. When measuring the luminance change according to the size of the white patch, the manufacturer not only locates the center of the white patch at the center of the display device 1, but also divides the center of the white patch horizontally and vertically to each position of the display module. It is possible to measure the luminance of the divided white patch.

5 is a diagram showing an image in which a luminance level difference can be visually recognized. 6 is a diagram illustrating an image displayed by a display device in which luminance is adjusted according to an exemplary embodiment.

Referring to FIG. 5, the disclosed display device 1 may display a frame including a white patch in the upper left corner on a black background.

Specifically, the first display module 10 displays an individual image occupying 90% of the white patch, and the second display module 11 displays an individual image occupying 20% of the white patch to the third display module 12 and the fourth display module. (13) may display an individual image including a black background.

As described above with reference to FIGS. 3 and 4, when the first display module 10 and the second display module 11 display individual images without adjusting the luminance, a difference in the number and amount of light emitted by the light sources occurs. . That is, even though the same white patch is displayed, the user visually recognizes a difference between the luminance of the white patch of the first display module 10 and the luminance of the white patch of the second display module 11 as shown in FIG. 5.

The display apparatus 1 solves the above-described problem by storing a target luminance value and adjusting the luminance of each area in which each display module 10, 11, 12, and 13 displays an image frame.

To this end, the display device 1 calculates a duty ratio for controlling the backlight unit.

Specifically, when each display module changes the size of the white patch on the black background illustrated in FIG. 5, the luminance may be measured. As the size of the white patch increases, the luminance of the white patch is measured higher, and as the size of the white patch decreases, the luminance of the white patch is measured to be lower. When the weight occupied by the white area is defined as p, the luminance measured in the white patch according to _p is defined as Y p (1 <P ≤ 100). If the target luminance value emitted by the display module displaying the white patch is Y _target , Equation 1 below may be set.

As described above, the target luminance value may be preset in the storage unit 130 by the manufacturer or may be received by the user through the input unit 120.

In the display module, _{a luminance value (Y tp} ) that needs to be added or subtracted to match the _{luminance Y p} to the Y _target may be defined as in Equation 2.

If the PWM duty cycle of the light source included in the backlight unit 160 is controlled to 10 bits, the duty ratio may be adjusted from 0 to 1023. When the luminance proportionally increases as the duty ratio increases, the luminance according to the modulation width may be expressed as Equation 3 below.

Where X is the duty ratio and Y is the luminance. When each display module is manufactured, a and b are values predetermined by experiment.

When the above equations are summarized, when the weight occupied by the white patch is P, the duty ratio (D _{p ) for the luminance Y tp} that needs to be adjusted to come out of the luminance of the _{Y target} will be calculated from Equations 4 and 5 below. I can.

When the duty ratio (D _p ) required for adjustment is calculated, the final duty ratio to be applied by the display module according to the size of the white patch is shown in Equation 6 below.

Here, the final duty ratio ranges from 0 to 1023.

Referring to FIG. 5 again, the first display module 10 displays a region of a frame having a white patch occupying 90% on a black background, and the second display module 11 has a white patch occupying 20%. Different areas of the frame can be displayed.

When the current duty ratio is controlled to 1023, D ₉₀ may be calculated as -179 and D ₂₀ may be calculated as -50 by the above-described equation. Accordingly, the first display module 10 may adjust the luminance by subtracting 179 from 1023 as the duty ratio and 844 as the duty ratio, and the second display module 11 may adjust the luminance by subtracting 50 from 1023 and 973 as the duty ratio.

Through this, the disclosed display device 1 displays a frame adjusted to a target luminance value, as shown in FIG. 6, and can reduce a luminance level difference.

7 is a flowchart illustrating a method of controlling a display device according to an exemplary embodiment.

Referring to FIG. 7, the display device 1 stores or receives a target luminance value (200 ).

The luminance target value may be set in advance by a manufacturer, and the first display module 10 may transmit the luminance target value stored in the storage unit 130 to the second display module 11 together with an image signal. Through the loop-out function, the display modules 10, 11, 12, and 13 can share the target luminance value.

Meanwhile, the target luminance value may be received or changed according to a user's input.

The first display module 10 receives an image signal (210).

The image signal may be composed of a plurality of frames, and the image signal is input to the first display module 10 through the source device 2.

The first display module 10 predicts the luminance of the first region of the frame (220).

The first display module 10 displays a plurality of frames. The first display module 10 distributes an image by a signal processing unit 110 operating as a splitter. Specifically, the first display module 10 may predict the luminance by determining the first region of the frame based on the positions of the remaining display modules 11, 12, and 13 and analyzing the first image to be displayed.

A method of analyzing an image by the first display module 10 may be various.

For example, the first display module 10 may determine the luminance of the image using an average picture level (APL) for each frame of the image. APL represents the average level of image brightness. If the APL is high, the image can be bright overall, and if the APL is low, the image is overall dark. The first display module 10 may predict the luminance based on the APL of the first area.

As another example, the first display module 10 may analyze a weight occupied by a bright portion based on a histogram distribution map. If the proportion occupied by the bright portion is larger than that of the dark portion, the first display module 10 may determine that the luminance is larger.

Meanwhile, the display module 10 may predict the luminance of an individual image to be displayed according to how close the center of a bright object included in the individual image is located than a reference position set by a manufacturer. The display module 10 may predict the luminance of an individual image by calculating a distribution ratio in which the silver object is located based on a brightly set reference position, and weighting according to the distribution ratio. Through this, the display module 10 may have a difference in luminance depending on the location of the patch even if the white patch of the same size is due to the location of the light source included in the backlight unit 160, the difference in the current load for each light source, or the difference in density of the light source. And predict the correct luminance.

The first display module 10 determines a duty ratio based on the predicted luminance and the difference between the luminance target value (230 ).

As described above with reference to FIGS. 5 and 6, the first display module 10 adjusts luminance to be added or subtracted so that the predicted luminance approaches a target luminance value. That is, the first display module 10 calculates a duty ratio equal to the luminance to be added or decreased.

The first display module 10 controls the backlight unit 160 based on the determined duty ratio (240).

The first display module 10 adjusts the luminance of the first area of the frame to be displayed through the backlight unit 160, so that the image displayed by the second display module 11 adjacent to the first display module 10 is The difference in luminance can be reduced.

The first display module 10 transmits an image signal to the second display module 11 (250), and the second display module 11 receives an image signal through a cable and an input/output port (260).

The second display module 11 predicts the luminance of the second region in the received frame (270 ).

Specifically, the second display module 11 may also generate an individual image to display the second area of the frame through image distribution. The second display module 11 predicts the luminance of the generated individual image. The method of predicting the luminance of the second area by the second display module 11 is the same as the operation of the first display module 10.

The second display module 11 determines a duty ratio based on the difference between the predicted luminance and the luminance target value (280).

5 and 6, the second display module 11 may increase or decrease the predicted luminance to approximate the target luminance value. However, the display modules 10, 11, 12, and 13 do not necessarily perform an operation of reducing the luminance, and may increase or maintain the luminance according to an image signal and a target luminance value.

The second display module 11 controls the backlight unit 160 based on the determined duty ratio (290).

Through this, the display apparatus 1 may reduce a difference in luminance that may occur in adjacent display modules 10, 11, 12, and 13 displaying the same image.

8 is a flowchart illustrating a method of controlling a display device according to another exemplary embodiment.

The display device 1 receives an image signal including a plurality of (n) frames (300), and the plurality of display modules 10, 11, 12, 13 adjusts the luminance of the first frame ( 310).

The method of adjusting the luminance by the plurality of display modules 10, 11, 12, 13 is the same as described above with reference to FIG. 7. However, the first frame need not necessarily correspond to the first frame listed in the video signal. That is, the display apparatus 10 may analyze the image signal and start the operation of the present invention with respect to a frame requiring brightness adjustment.

The display device 1 displays a first frame whose luminance is adjusted through a plurality of display modules 10, 11, 12, and 13 (320).

The display apparatus 1 analyzes an image signal of a preset number (n) of frames among a plurality of frames (330).

A method of analyzing images of a preset number of frames is based on APL or histogram distribution. For example, the display device 1 may calculate APL for a preset number of frames. As another example, the display apparatus 1 may calculate an average of a histogram distribution map for a preset number of frames.

The display device 1 compares the image analysis result with the first frame (340).

If the average of the distribution of the APL or the histogram is compared with the first frame among n frames and exceeds a preset reference value or more, the display device 1 slowly adjusts the luminance for a predetermined time (350).

However, if the average of the distribution map of the APL or the histogram is less than a preset reference value when compared with the first frame (hereinafter, referred to as the first frame) among n frames, the display device 1 Without performing the control (360), light source control according to the image signal is performed.

In the exemplary embodiment of FIG. 7, a method of adjusting the luminance of one frame in the display device 1 has been described. However, if the display apparatus 1 adjusts the luminance of all the frames of a plurality of frames that are input, the user can watch the continuously adjusted image and the image having a luminance different from the intended image. Accordingly, the display apparatus 1 analyzes a preset number of frames and determines whether to control the backlight unit based on the analyzed result. Here, the preset number may vary according to at least one of a manufacturer's setting, an image signal, or a user's input.

Through this, the display device 1 can overcome a weakening of the user's visibility according to a difference in luminance, and provide an image without a sense of heterogeneity.

1: display device 10, 11, 12, 13: display module
110: signal processing unit 120: input unit
130: storage unit 140: control unit
150: liquid crystal panel 160: backlight unit
170: sound output unit

Claims (15)

A storage unit for storing a preset luminance target value; And
Including; a liquid crystal panel, a backlight unit, and a plurality of display modules including a control unit for controlling the liquid crystal panel and the backlight unit,
The first display module,
Receives an image signal including a plurality of frames, predicts luminance of a frame region corresponding to the first display module, and controls the backlight unit based on a difference between the predicted luminance and the luminance target value and,
The second display module,
Receiving the image signal transmitted from the first display module, predicting the luminance of a frame region corresponding to the second display module, and the controller based on the difference between the predicted luminance and the target luminance value, A display device that controls a light unit. The method of claim 1,
The first display module and the second display module,
The difference between the predicted luminance and the target luminance value is calculated as a duty ratio based on the determined luminance and a preset reference value,
A display device in which the controller controls the backlight unit based on the calculated duty ratio. The method of claim 1,
The first display module and the second display module,
A display device that predicts luminance based on an average picture level (APL). The method of claim 1,
The first display module and the second display module,
A display device that predicts luminance based on a histogram distribution of an image. The method of claim 1,
The backlight circuit,
A light source including a plurality of light emitting diodes; And
And a light guide plate for diffusing light emitted by a light source therein and emitting the light to the liquid crystal panel. The method of claim 1,
Further comprising; an input unit for receiving a user input,
The target luminance value is changed by the input. The method of claim 1,
The first display module,
Based on the APL or histogram distribution map, the luminance of a preset number of frames among the plurality of frames controls the backlight unit so that the change in luminance is not visually recognized,
The second display module,
A display device that controls the backlight unit so that the luminance of a preset number of frames transmitted from the first display module is not visually recognized. In the control method of a display device including a plurality of display modules,
Storing a preset luminance target value;
Predicting the luminance of the frame area corresponding to the first display module;
A first display module displays the frame area based on a difference between the predicted luminance and the luminance target value;
A second display module receiving the image signal transmitted from the first display module;
Predicting the luminance of a frame area corresponding to the second display module;
And displaying the frame area by a second display module based on a difference between the predicted luminance and the target luminance value. The method of claim 8,
The first display module and the second display module predicting luminance,
And calculating a difference between the predicted luminance and the target luminance value as a duty ratio based on the predicted luminance and a preset reference value. The method of claim 9,
When the first display module and the second display module display the frame area,
Controlling a backlight unit based on the calculated duty ratio. The method of claim 8,
The first display module and the second display module predicting luminance,
Predicting luminance based on an average picture level (APL). The method of claim 8,
The first display module and the second display module predicting luminance,
Predicting luminance based on the histogram distribution of the image. The method of claim 8,
Receiving a user's input; further includes,
And the preset luminance target value is changed by the user's input. The method of claim 8,
Predicting the luminance of the frame region corresponding to the first display module,
Predicting, by the first display module, a change in the luminance in a preset number of frames among the plurality of frames based on an APL or a histogram distribution map; Including,
When the first display module displays the frame area,
Controlling the backlight unit so that the change in luminance is not visually recognized. The method of claim 14,
Predicting the luminance of the frame region corresponding to the second display module,
Including; a second display module predicting the change in the luminance in the preset number of frames based on the APL or the histogram distribution map,
When the second display module displays the frame area,
Controlling the backlight unit so that the change in luminance is not visually recognized.

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