KR20120018255A - Liquid crystal display and local dimming method used in the same - Google Patents

Abstract

PURPOSE: An LCD(Liquid Crystal Display) apparatus and local dimming control method are provided to improve color reproduction by improving contrast range. CONSTITUTION: A liquid crystal panel displays images as an LVD(Low Voltage Differential) signal which is inputted from the outside. A light source operating module creates a color operating signal by modulating an I2C(Inter-Integrated Circuit) signal inputted from the outside through a PWM(Pulse Width Modulation) method. The light source module is arranged at plural light emitting blocks. A color operating signal transmitted by the light source module is controlled. An image signal control module(140) establishes a pixel block among a red LED(Light Emitting Diode), a green LED, and a blue LED. The brightness of the light source is locally controlled by determining the final value of the pixel block.

Description

Liquid crystal display and local dimming control method using the same {LIQUID CRYSTAL DISPLAY AND LOCAL DIMMING METHOD USED IN THE SAME}

The present invention relates to a liquid crystal display and a local dimming control method using the same. Specifically, pixels to which one R LED, G LED, or B LED is applied are set to one pixel block, and an average brightness value of each pixel block is set. The present invention relates to a liquid crystal display and a local dimming control method using the same, which locally controls the brightness of each pixel block by using the central average brightness value of each pixel block and the average brightness value of a previous image frame.

In general, the liquid crystal display includes a liquid crystal display panel that displays an image by adjusting the light transmittance of the liquid crystal, and a backlight unit disposed under the liquid crystal display panel to provide light to the liquid crystal display panel.

The liquid crystal display panel includes an array substrate having pixel electrodes and thin film transistors electrically connected to the pixel electrodes, a color filter substrate having a common electrode and color filters, and a liquid crystal layer interposed between the array substrate and the color filter substrate. It includes.

The arrangement of the liquid crystal layer is changed by an electric field formed between the pixel electrodes and the common electrode, thereby changing the transmittance of light passing through the liquid crystal layer. Herein, when the transmittance of the light is increased to the maximum, the liquid crystal display panel may implement a white image having high luminance, whereas when the transmittance of the light is reduced to the minimum, the liquid crystal display panel may implement a black image having low luminance. .

However, since it is difficult for the liquid crystal layer to be generally arranged in a completely constant direction, light leakage may occur at the low gray level of the liquid crystal display panel. That is, it is difficult for the liquid crystal display panel to realize a complete black image at low gray scale values, and thus the contrast ratio (CR) of the image displayed on the liquid crystal display panel may be reduced.

In order to prevent the contrast ratio of the image from being reduced, the backlight unit may be driven by a local dimming method in which light may be individually controlled to emit light. The backlight unit may employ cold cathode fluorescent lamps, but recently, light emitting diodes (LEDs) having low power consumption and high color reproducibility are employed.

The local dimming technique divides the backlight unit into a plurality of blocks and emits light with different luminance for each block. For example, the one-dimensional dimming technique may be employed when the light source of the backlight unit is made of a linear lamp, and the two-dimensional dimming technique may be employed when the light source is made of a light emitting diode.

In addition, a three-dimensional dimming technology has been developed in which the light source employs red, green, and blue light emitting diodes to drive dimming for each color as well as luminance. In the three-dimensional dimming technique, as the red, green, and blue light emitting diodes having different color coordinates and luminance changes with time are employed, there is a difficulty in correcting the amount of light having a constant color coordinate and luminance.

The present invention is to solve the above problems, and set the pixel to which one R LED, G LED, B LED is applied to one pixel block, the average brightness value of each pixel block and the center of each pixel block A liquid crystal display device and a local dimming control method using the same to improve contrast ratio by locally controlling the brightness of each pixel block using the average brightness value and the average brightness value of the previous image frame. The purpose is to provide.

In addition, the present invention sets a pixel to which one R LED, G LED, B LED is applied to one pixel block during local dimming control, and the average brightness value of each pixel block and the central average brightness value of each pixel block. And by controlling the brightness of each pixel block locally using the average brightness value of the previous image frame, the frame data of the entire image is stored in the memory, and the process of eliminating the drawing after analysis is eliminated, thereby reducing the delay time of the image when outputting the image. Another object is to provide a liquid crystal display and a local dimming control method using the same.

Features of the present invention for achieving the above object,

A liquid crystal panel which displays an image with an LVDS signal input from the outside; A light source driving module for generating a color driving signal by PWM-modulating the I2C signal input from the outside; A light source module in which a plurality of light emitting blocks comprising a plurality of RGB LEDs are arranged and whose brightness is controlled by a color driving signal output from the light source driving module; The pixel to which one of the R, G, and B LEDs of the light source module is applied is set to one pixel block, and according to a user's input, the current average brightness value L _{block (i)} of the pixel block and the pixel The final value L _{final (i)} of the pixel block is obtained by using the current center average brightness value L _{center (i)} of the block and the average brightness value L _{frame (i)} of the previous image frame of the light source module. And determining an image signal control module to locally control the brightness of the light source module.

The image signal control module may include a first signal converter configured to convert an LVDS signal output from the liquid crystal display into a TTL signal; By using the TTL signal output from the first signal converter, the average brightness value L _{block (i)} , the center average brightness value L _{center (i} ) and the average brightness value L _{frame ( i)} ), and compare these values with each other to determine the final value (L _{final (i)} ) according to the comparison result, and generate an I2C signal based on the output to the light source driving module, and outputs the TTL signal A local dimming control unit for transmitting; An image corrector configured to correct the TTL signal transmitted from the local dimming controller according to a user input; And a second signal converter converting the TTL signal output from the image corrector into an LVDS signal and outputting the LVDS signal to the liquid crystal panel.

Here, the local dimming controller compares the average brightness value L _{block (i)} with the average brightness value L _{frame (i)} of the previous image frame, and compares the average brightness value L _{block (i) with each other} . If the average brightness value L _{frame (i)} of the previous image frame is larger than the average brightness value L _{block (i)} , the average brightness value L _{block (i)} is set to an enhanced value L _{enhanced (i) .} ), the average brightness of the preceding image frame value (L _{frame (i)} is less than or equal to the average brightness) value of the average brightness of the previous image frame in the (L _{frame (i))} value the average brightness (L _{frame (i))} values ( setting the L _{frame (i))} as ppaenhu constant value (increasing the value obtained by subtracting the value obtained by multiplying the _{T) (L enhanced (i)} ), and increase the value (L _{enhanced (i))} and the central average brightness value (L _{center (i)} ) is compared with each other, if the center average brightness value L _{center (i} ) is greater than the _enhanced value L _{enhanced (i)} , the center average brightness value L _{center (i)} is compared to the final value L _{final (i )),} the setting, and the average brightness value of the center _(center L _(i)) increases It is less than _{(L enhanced (i))} equal to or sets a gain value _{(L enhanced (i))} to a final value _(final L _(i)).

Here, the center average brightness value L _{center (i)} is an average brightness value of a pixel block located at 1/4 to 3/4 points with respect to the center point of the width × length of the light emitting block.

Here, the local dimming control unit performs mapping of the final value L _{final (i)} according to the position of the RGB LED of the light source module when outputting the I2C signal to the light source driving module.

According to another aspect of the present invention,

A local dimming driving method using the liquid crystal display device, the method comprising: a first step of converting an LVDS signal input from an external device by converting a TTL signal into a first signal converter; The local dimming control unit receives the converted TTL signal, and a current average brightness value L _{block (i)} of the pixel block included in each light source block of the light emitting module, and a current median average brightness value L of the pixel block. _{center (i)} ) and extracting an average brightness value L _{frame (i)} of a previous image frame of the light source module; The average brightness value L _{block (i)} extracted by the local dimming control unit, the center average brightness value L _{center (i} ) and the average brightness value L _{frame (i)} of the previous image frame are compared with each other. Determining a final value L _{final (i)} of the pixel block according to the comparison result; And generating an I2C signal based on the determined final value L _{final (i)} , outputting the I2C signal to the light source driving module, and locally controlling the brightness of the light source module and transmitting the TTL signal. Characterized in that made.

Here, the local dimming control method using the liquid crystal display device includes a fifth step of correcting the TTL signal transmitted from the local dimming control unit according to a user input; And a sixth step of converting the TTL signal output from the image corrector into an LVDS signal in a second signal converter and outputting the LVDS signal to the liquid crystal panel.

Here, in the third step, the local dimming control unit compares the average brightness value L _{block (i} ) with the average brightness value L _{frame (i)} of the previous image frame, and compares the average brightness value ( If L _{block (i)} ) is greater than the average brightness value L _{frame (i)} of the previous image frame, the third brightness value L _{block (i} ) is set as an _enhanced value L _{enhanced (i)} . Steps; The average of the previous image frame on the average brightness value _{(L frame (i))} is less than or equal to the average brightness value _{(L frame (i))} of the average gray level in the local dimming control just before the _{(L block (i))} image frame 3-2 which sets the value obtained by subtracting the average brightness value L _{frame (i)} from the brightness value L _{frame (i)} and subtracting the value multiplied by the constant value T to the enhanced value L _{enhanced (i)} Steps; The gain value _{(L enhanced (i))} and the center average brightness value _{(L center (i))} for intercomparison with the center average brightness value _{(L center (i))} gain value in the local dimming control (L _{enhanced ( i) setting the} center average brightness value L _{center (i} ) to a final value L _{final (i)} if greater than _i) ; And wherein the local dimming control brightness center average value _{(L center (i))} the gain value _{(L enhanced (i))} of less than or equal to the increased value _{(L enhanced (i))} final value _{(L final (i))} It includes the third step to set the.

Here, in the fourth step, when the I2C signal is output from the local dimming controller to the light source driving module, the final value L _{final (i)} is mapped according to the position of the RGB LED of the light source module.

Here, the pixel block is a pixel to which each of the R LED, G LED, and B LED of the light source module is applied.

Here, the center average brightness value L _{center (i)} is an average brightness value of a pixel block located at 1/4 to 3/4 points with respect to the center point of the width × length of the light emitting block.

According to the liquid crystal display device and the local dimming control method using the same according to the present invention configured as described above, the pixel to which one R LED, G LED, B LED is applied to one pixel block, the average brightness value of each pixel block In addition, the contrast ratio may be improved by locally controlling the brightness of each pixel block by using the central average brightness value of each pixel block and the average brightness value of the previous image frame, thereby improving color reproducibility.

In addition, according to the present invention, in the local dimming control, a pixel to which one R LED, a G LED, or a B LED is applied is set to one block, and an average brightness value of each pixel block and a central average brightness value of each pixel block are set. And by controlling the brightness of each pixel block locally using the average brightness value of the previous image frame, the frame data of the entire image is stored in the memory, and the process of eliminating the drawing after analysis is eliminated, thereby reducing the delay time of the image when outputting the image. have.

1 is a block diagram schematically showing the configuration of a liquid crystal display according to the present invention.
2 is a block diagram schematically illustrating a configuration of an image signal control module of a liquid crystal display according to the present invention.
3 is an explanatory diagram for describing a pixel block according to the liquid crystal display according to the present invention.
4 is a signal flowchart illustrating a signal processing process of the liquid crystal display according to the present invention.
5A and 5B are flowcharts illustrating an operation of a local dimming control method using a liquid crystal display according to the present invention.

Hereinafter, the configuration of the liquid crystal display according to the present invention will be described in detail with reference to the accompanying drawings.

In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intentions or customs of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification.

1 is a block diagram schematically showing the configuration of a liquid crystal display according to the present invention, FIG. 2 is a block diagram schematically showing the configuration of an image signal control module among the liquid crystal display according to the present invention, and FIG. FIG. 4 is an explanatory diagram for explaining a pixel block according to the liquid crystal display according to the present invention, and FIG. 4 is a signal flowchart for explaining a signal processing process of the liquid crystal display according to the present invention.

1 to 4, the liquid crystal display device 100 according to the present invention includes a liquid crystal panel 110, a light source driving module 120, a light source module 130, and an image signal control module 140. Include.

First, the liquid crystal panel 110 includes a plurality of pixels and displays an image as an LVDS signal output from an image signal control module to be described below.

The light source driving module 120 modulates the I2C signal output from the image signal control module 140 into a PWM signal to generate a color driving signal. Here, the color drive signals include R, G, and B drive signals, and each drive signal is a pulse width modulated PWM signal.

In addition, the light source module 130 includes a plurality of light emitting blocks in which a plurality of RGB LEDs are arranged, and the brightness is controlled by a color driving signal output from the light source driving module 120. As illustrated in FIG. 3, the light source module 130 sets a combination of pixels that each of the R LEDs, the G LEDs, and the B LEDs serves as one pixel block PB. Here, in addition to the RGB LED may further include a W (White) LED, the wavelength of the R LED is about 580nm to 700nm, the wavelength of the G LED is about 460nm to 630nm. The wavelength of the B LED is about 400 nm to 500 nm.

Also, as illustrated in FIG. 2, the image signal control module 140 includes a first signal converter 141, a local dimming controller 143, an image corrector 145, and a second signal converter 147. It is composed.

The first signal converter 141 converts the LVDS signal output from the liquid crystal display (not shown) into a TTL signal.

As illustrated in FIG. 4, the local dimming controller 143 sequentially adds current brightness values of pixels of an image corresponding to each pixel block PB by using a TTL signal output from the first signal converter 141. Is the average brightness value L _{block (i)} divided by the number of pixels in a block, and the sum of the brightness values immediately before the pixel blocks PB of the image frame immediately before the image frame of the light source module divided by the number of pixel blocks. value _{(L frame (i))} the average brightness value by mutually comparing _{(L block (i))} is an average brightness of the preceding image frame value greater average brightness than that _{(L frame (i))} values _{(L block (i))} to Set to the _enhanced value (L _{enhanced (i)} ). Further, the local dimming control unit 143 immediately before the average brightness value L _{frame (i) when} the average brightness value L _{block (i)} is less than or equal to the average brightness value L _{frame (i)} of the previous image frame. Subtract the average brightness value L _{frame (i)} from the average brightness value L _{frame (i)} of the image frame and set the value obtained by subtracting the value multiplied by the constant value T to L _{enhanced (i)} . . In addition, the local dimming controller 143 may divide the sum of the current brightness values of the center portion among the pixels of the image corresponding to the L enhancement _(i) and the pixel block PB by the number of pixels in the center portion. Comparing the values L _{center (i)} , and when the center average brightness L _{center (i} ) is greater than the L _{enhanced (i)} , the center average brightness L _{center (i)} is determined as the final value ( L _{final (i)} ) In addition, the local dimming control unit 143 may adjust the final value L _{final (} L _{final ( i)} if the average brightness value L _{center (i)} is less than or equal to the enhanced value L _{enhanced (i)} . _i) ). In this case, the center average brightness value L _{center (i)} is an average brightness value of pixels positioned at 1/4 to 3/4 points with respect to the horizontal X length center point of one light emitting block. In addition, the local dimming control unit 143 performs mapping of the final value L _{final (i)} according to the position of the RGB LED of the light source module 130 when outputting the I2C signal to the light source driving module 120.

The image corrector 145 corrects the TTL signal transmitted from the local dimming controller and corrects the TTL signal according to the input of the output curve compared to the input image that the user prefers.

The second signal converter 147 converts the TTL signal output from the image corrector 145 into an LVDS signal and outputs the LVDS signal to the liquid crystal panel 110.

On the other hand, the liquid crystal display device according to the present invention is preferably manufactured by modifying the commercialized product, after removing the backlight unit from the back plate is formed in a rectangular shape, a plurality of RGB LEDs arranged on the upper surface in a hexagonal shape light emission Attach the thermal pad to the back of the block.

Then, after attaching the thermal pad side to the back plate, an optical sheet is attached to the upper surface of the light source module.

Thus, the light emitting blocks are arranged in the above order to complete the backlight unit. In this case, the light source driving module may be directly mounted on the rear surface of the light emitting block to be electrically connected thereto or separately mounted on a board to be electrically connected to the light emitting block.

Hereinafter, a local dimming control method using a liquid crystal display according to the present invention will be described in detail with reference to the accompanying drawings.

5A and 5B are flowcharts illustrating an operation of a local dimming control method using a liquid crystal display according to the present invention.

5A and 5B, first, the first signal converter 141 converts and outputs an LVDS signal input from the outside by converting a TTL signal (S10).

Then, the local dimming control unit 143 uses the TTL signal output from the first signal converter 141 to present the current average brightness value L _{block (i) of} the pixel block PB and the current center of the pixel block. The average brightness value L _{center (i)} is obtained and the average brightness value L _{frame (i)} of the current image frame is extracted using the average brightness values of the current pixel blocks (S20). In this case, the obtained average brightness value of the current image frame is stored and used for calculation of the next frame.

Then, the local dimming control unit 143 determines the current average brightness value L _{block (i} ) of the pixel block PB, the current center average brightness value L _{center (i)} of the pixel block PB, and The average brightness value L _{frame (i)} of the previous image frame is compared with each other (S31).

Then, the local dimming control unit 143 compares the average brightness value L _{block (i)} with the average brightness value L _{frame (i)} of the previous image frame (S32) and the average brightness value L _{block. (i)} ) is larger than the average brightness value L _{frame (i)} of the previous image frame, the average brightness value L _{block (i} ) is increased by L _{enhanced (i} ) (that is, L _{enhanced (i)} = L _{block (i)} ) (S33). On the contrary, the local dimming control unit 143 compares the average brightness value L _{block (i)} with the average brightness value L _{frame (i)} of the previous image frame and compares the average brightness value L _{block (i} ) with each other. the average brightness of the preceding image frame value _{(L frame (i))} is less than or equal to the average brightness value of the average brightness of the preceding image frame in the _{(L frame (i))} value of the average brightness _{(L frame (i))} values (L _frame subtract _(i) ) and then multiply by the constant value (T) to get L _{enhanced (i)} ) (i.e. L _{enhanced (i)} = L _{block (i)} + T × (L _{frame (i )} -L _{block (i)} ) (S33-1) At this time, the constant value T can be arbitrarily changed according to the setting.

When the enhancement value L _{enhanced (i)} is determined, the local dimming control unit 143 compares the enhancement value L _{enhanced (i} ) with the center average brightness value L _{center (i)} (S34).

Thus, the local dimming control unit 143 is a brightness center average value (L _{center (i)),} the gain value is greater central average brightness value than the (L _{enhanced (i))} (L _{center (i)),} final value (L _{final ( i)} ) (i.e., L _{final (i)} = L _{center (i)} ) is set (S35). On the other hand, the central average brightness value _{(L center (i))} increases the value of _{(L enhanced (i))} is less than or equal to the increased value _{(L enhanced (i))} final value _{(L final (i))} (i.e., L _{final (i)} = L _{enhanced (i)} ) is set (S35-1).

Meanwhile, when the final value L _{final (i)} is determined, the local dimming control unit 143 performs mapping of the final value L _{final (i)} according to the position of the RGB LED of the light source module 130 (S41). In operation S43, an I 2 C signal is generated using the mapped final value L _{final (i)} , and is output to the light source driving module 120 to locally control the brightness of the light source module 130 (S43).

In addition, when the user requests an image correction by determining a correction curve (eg, contrast, color reproducibility, etc.) with respect to the input image signal (S51), the image correction unit 145 is transmitted from the local dimming control unit 143. The corresponding correction amount of the TTL signal is determined (S52), and changed to the corrected TTL signal corresponding thereto (S53). At this time, the correction curve requested by the user to the image correction unit 145 is preferably stored in a table form of an array form that can have the form of the output compared to the input of the corresponding correction TTL signal.

Then, the second signal converter 147 converts the corrected TTL signal output from the image corrector 145 into an LVDS signal and outputs the LVDS signal to the liquid crystal panel 110 to display an image (S60). On the other hand, when the user does not request correction of the input image signal through the image correction unit 145 of the image signal control module 140, the image correction unit 145 may use the TTL signal transmitted from the local dimming control unit 143 as it is. Output

As those skilled in the art would realize, the described embodiments may be modified in various ways, all without departing from the spirit or scope of the present invention. It is to be understood, however, that the present invention is not limited to the specific forms referred to in the description, but rather includes all modifications, equivalents, and substitutions within the spirit and scope of the invention as defined by the appended claims. Should be.

110: liquid crystal panel 120: light source drive module
130: light source module 140: video signal control module
141: first signal converter 143: image correction unit
145: local dimming control unit 147: second signal converter
PB: Pixel Block

Claims (11)

A liquid crystal panel which displays an image with an LVDS signal input from the outside;
A light source driving module for generating a color driving signal by PWM-modulating the I2C signal input from the outside;
A light source module in which a plurality of light emitting blocks comprising a plurality of RGB LEDs are arranged and whose brightness is controlled by a color driving signal output from the light source driving module;
The pixel to which one of the R, G, and B LEDs of the light source module is applied is set to one pixel block, and according to a user's input, the current average brightness value L _{block (i)} of the pixel block and the pixel The final value L _{final (i)} of the pixel block is obtained by using the current center average brightness value L _{center (i)} of the block and the average brightness value L _{frame (i)} of the previous image frame of the light source module. And a video signal control module for determining and locally controlling the brightness of the light source module. The method of claim 1,
The video signal control module,
A first signal converter converting the LVDS signal output from the liquid crystal display into a TTL signal;
By using the TTL signal output from the first signal converter, the average brightness value L _{block (i)} , the center average brightness value L _{center (i} ) and the average brightness value L _{frame ( i)} ), and compare these values to each other to determine the final value (L _{final (i)} ) according to the comparison result, based on this I2C signal is generated and output to the light source drive module, and the TTL signal A local dimming control unit for transmitting;
An image corrector configured to correct the TTL signal transmitted from the local dimming controller according to a user input; And
And a second signal converter converting the TTL signal output from the image corrector into an LVDS signal and outputting the LVDS signal to the liquid crystal panel. The method of claim 1,
The local dimming control unit,
The average brightness value L _{block (i)} and the average brightness value L _{frame (i)} of the previous image frame are compared with each other so that the average brightness value L _{block (i)} is the average brightness value of the previous image frame ( L _{frame (i)} ), the average brightness value L _{block (i)} is set to the enhanced value L _{enhanced (i)} , and the average brightness value L _{block (i)} is the average brightness value of the previous image frame. _{(L frame (i))} the constant a is less than or equal to the average brightness value of the average brightness of the preceding image frame in the _{(L frame (i))} value of the average brightness _{(L frame (i))} values _{(L frame (i))} ppaenhu The value obtained by subtracting the value (T) is set as an enhanced value (L _{enhanced (i)} ), and the enhanced value (L _{enhanced (i)} ) and the center average brightness value (L _{center (i)} ) are compared with each other to form a center. If the average brightness value L _{center (i)} is greater than the L _{enhanced (i)} value, the center average brightness value L _{center (i)} is set to the final value L _{final (i)} and the center average brightness value is set. If value L _{center (i )} is less than or equal to L _{enhanced (i)} The liquid crystal display device of the _{enhanced (i))} characterized in that for setting the final value _(final L _(i)). The method of claim 3, wherein
The center average brightness value L _{center (i} ) is
And an average brightness value of pixel blocks positioned at 1/4 to 3/4 of the light emitting block based on the center point of the width × length of the light emitting block. The method of claim 3, wherein
The local dimming control unit,
And outputting a final value (L _{final (i)} ) according to the position of the RGB LED of the light source module when outputting the I2C signal to the light source driving module. In the local dimming driving method using the liquid crystal display device of claim 1,
A first step of converting and outputting a TLS signal from an external LVDS signal by a first signal converter;
The local dimming control unit receives the converted TTL signal, and a current average brightness value L _{block (i)} of the pixel block included in each light source block of the light emitting module, and a current median average brightness value L of the pixel block. _{center (i)} ) and extracting an average brightness value L _{frame (i)} of a previous image frame of the light source module;
The average brightness value L _{block (i)} extracted by the local dimming control unit, the center average brightness value L _{center (i} ) and the average brightness value L _{frame (i)} of the previous image frame are compared with each other. Determining a final value L _{final (i)} of the pixel block according to the comparison result;
A fourth step of generating an I2C signal based on the determined final value L _{final (i)} and outputting the I2C signal to a light source driving module to locally control the brightness of the light source module and to transmit the TTL signal. Local dimming control method using a liquid crystal display, characterized in that. The method according to claim 6,
Local dimming control method using the liquid crystal display,
A fifth step of correcting the TTL signal transmitted from the local dimming controller according to a user input;
And a sixth step of converting the TTL signal output from the image corrector into an LVDS signal in a second signal converter and outputting the converted TDS signal to the liquid crystal panel. The method according to claim 6,
The third step,
In the local dimming control the average brightness value _{(L block (i))} and the average luminance of the immediately preceding video frame value _{(L frame (i))} and are compared to the average brightness value _{(L block (i))} is immediately before the image Setting the average brightness value L _{block (i} ) to an increased value L _{enhanced (i)} when the _frame is larger than the average brightness value L _{frame (i)} ;
The average of the previous image frame on the average brightness value _{(L frame (i))} is less than or equal to the average brightness value _{(L frame (i))} of the average gray level in the local dimming control just before the _{(L block (i))} image frame 3-2 which sets the value obtained by subtracting the average brightness value L _{frame (i)} from the brightness value L _{frame (i)} and subtracting the value multiplied by the constant value T to the enhanced value L _{enhanced (i)} Steps;
The gain value _{(L enhanced (i))} and the center average brightness value _{(L center (i))} for intercomparison with the center average brightness value _{(L center (i))} gain value in the local dimming control (L _{enhanced ( i) setting the} center average brightness value L _{center (i} ) to a final value L _{final (i)} if greater than _i) ; And
The the local dimming control center average brightness value _{(L center (i))} the gain value _{(L enhanced (i))} of less than or equal to the increased value _{(L enhanced (i))} final value _{(L final (i))} Local dimming control method using a liquid crystal display device comprising the step of setting 3-4. The method according to claim 6,
The fourth step,
Local dimming using the liquid crystal display device when the local dimming control unit outputs the I2C signal to the light source driving module according to the position of the RGB LED of the light source module according to the position of the final LED (L _{final (i)} ) Control method. The method according to claim 6,
The pixel block,
Local dimming control method using a liquid crystal display device, characterized in that the pixel is applied to each of the R LED, G LED, B LED of the light source module. The method according to claim 6,
The center average brightness value L _{center (i} ) is
Local dimming control method using a liquid crystal display device, characterized in that the average brightness value of the pixel block located in the 1/4 ~ 3/4 point relative to the center point of the horizontal × vertical of the light emitting block.

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