KR101327841B1 - Apparatus and method for driving liquid crystal display device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving apparatus and a driving method of a liquid crystal display device which can maintain a constant power consumption irrespective of a display image and improve partial luminance of the display image.

An apparatus for driving a liquid crystal display according to the present invention includes an image display unit including a liquid crystal cell formed for each region defined by a plurality of gate lines and a plurality of data lines, and a plurality of lamps arranged side by side and between the lamps. The backlight for irradiating light to the image display unit using a plurality of LED arrays having a plurality of LEDs (Light Emitting Diode) and the input data from the outside are displayed on the image display unit, and the image display unit is arranged in a plurality of blocks. A driving circuit unit configured to generate a plurality of lamp dimming signals and a plurality of LED dimming signals according to the sum of the maximum gray scales of each block, and a backlight driving unit driving the backlight according to the lamp dimming signals and the LED dimming signals. Characterized in that comprises a.

Lamps, Light Emitting Diodes, Dimming, Splitting, Blocks, Partial Luminance

Description

TECHNICAL FIELD [0001] The present invention relates to a driving apparatus and a driving method for a liquid crystal display device,

1 is a view schematically showing a driving device of a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 2 is a block diagram schematically illustrating the timing controller shown in FIG. 1. FIG.

FIG. 3 is a block diagram schematically illustrating the backlight control unit illustrated in FIG. 2.

FIG. 4 is a diagram showing a block of an image display unit divided by the maximum gradation detection unit for each block shown in FIG. 3; FIG.

FIG. 5 is a graph illustrating a reference dimming curve for a plurality of LEDs stored in a memory unit shown in FIG. 3.

FIG. 6 is a block diagram schematically illustrating the backlight driving unit shown in FIG. 1. FIG.

7 is an exploded perspective view schematically showing the backlight shown in FIG.

8A is a diagram illustrating a spot image.

FIG. 8B is a view showing a driving state of a backlight for the spot image shown in FIG. 8A according to the embodiment of the present invention; FIG.

9A shows a dark image.

FIG. 9B is a view showing a driving state of a backlight for the dark image shown in FIG. 9A according to an embodiment of the present invention; FIG.

10A shows a bright image.

FIG. 10B is a view showing a driving state of a backlight for the bright image shown in FIG. 10A according to the embodiment of the present invention; FIG.

Description of the Related Art [0002]

2: image display unit 4: backlight

6: driving circuit section 8: backlight driving section

20: timing controller 30: gate driver

40: data driver

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a driving device and a driving method of a liquid crystal display device which can maintain a constant power consumption irrespective of a display image and improve partial luminance of the display image.

In general, a liquid crystal display is a back light by a liquid crystal panel composed of a plurality of liquid crystal cells arranged in a mattress shape and a plurality of control switches for switching image signals to be supplied to the liquid crystal cells. ), The amount of light transmitted is adjusted to display a desired image on the screen.

Conventional backlight is divided into a direct method of directly illuminating the light source by arranging the light source on the back of the liquid crystal panel and an edge method of reflecting and diffusing light by a light guide plate and a reflecting plate by placing the light source on one side or both sides of the liquid crystal panel. Lose. The direct method uses a plurality of lamps to directly irradiate light onto the liquid crystal panel, so that the luminance is high and is mainly used for a large liquid crystal display device.

Such a conventional backlight irradiates a liquid crystal panel with light of a constant luminance at all times regardless of a display image displayed on the liquid crystal panel.

Accordingly, since the conventional backlight always has a constant luminance irrespective of the display image, it is impossible to more vividly express an image that partially requires high luminance, such as a blasting scene. In addition, the conventional backlight always has a constant brightness, so the power consumption is high.

Accordingly, in order to solve the above problems, the present invention provides a driving apparatus and a driving method of a liquid crystal display device which can maintain a constant power consumption irrespective of a display image and improve partial luminance of the display image. have.

A driving device of a liquid crystal display according to an exemplary embodiment of the present invention for achieving the above object is arranged in parallel with an image display unit including a liquid crystal cell formed for each region defined by a plurality of gate lines and a plurality of data lines. A backlight for irradiating light to the image display unit by using a plurality of LED arrays having a plurality of lamps and a plurality of LEDs (Light Emitting Diodes) disposed between the lamps, and input data from the outside to the image display unit. A driving circuit unit configured to divide the image display unit into a plurality of blocks and generate a plurality of lamp dimming signals and a plurality of LED dimming signals according to the sum of the maximum grays for each block, the lamp dimming signal and the LED dimming signal; According to the configuration characterized in that it comprises a backlight drive unit for driving the backlight.

A driving method of a liquid crystal display according to an exemplary embodiment of the present invention is a driving method of a liquid crystal display including an image display unit having a liquid crystal cell formed for each region defined by a plurality of gate lines and a plurality of data lines. A first step of dividing the display into a plurality of blocks and generating a plurality of lamp dimming signals and a plurality of LED dimming signals according to the sum of the maximum gray scales for each block; and arranged between the plurality of lamps arranged side by side and the lamps A second step of driving a backlight composed of a plurality of LED arrays having a plurality of LEDs according to the lamp dimming signals and the LED dimming signals, and supplying an image signal corresponding to the input data to the image display unit It is characterized by comprising a third step.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings and embodiments.

1 is a view schematically illustrating a driving device of a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a driving apparatus of a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal cell formed for each region defined by n gate lines GL1 to GLn and m data lines DL1 to DLm. Back light 4 for irradiating light to the image display unit 2 by using the image display unit 2, a plurality of lamps arranged side by side, and a plurality of light emitting diode arrays arranged between the lamps, and the image display unit 2. Back light 4 for irradiating light) and an image corresponding to input data (Data) input from the outside are displayed on the image display unit 2, and the image display unit 2 is divided into a plurality of blocks for each block. The driving circuit unit 6 which generates a plurality of lamp dimming signals HDim and a plurality of LED dimming signals BDim according to the sum of the maximum gray scales, and the lamp dimming signals HDim and each LED dimming signal BDim. The backlight driving the backlight 50 along It is configured to include an 8.

The image display unit 2 includes a thin film transistor TFT formed in an area defined by n gate lines GL1 through GLn and m data lines DL1 through DLm, and liquid crystal cells connected to the thin film transistor TFT. Equipped. The thin film transistor TFT supplies a data signal from the data lines DL1 to DLm to the liquid crystal cell in response to the gate-on voltages from the gate lines GL1 to GLn. The liquid crystal cell may be equivalently represented as the liquid crystal capacitor Clc since the liquid crystal cell includes a common electrode facing the liquid crystal and a sub pixel electrode connected to the thin film transistor TFT. The liquid crystal cell also includes a storage capacitor Cst for maintaining the data signal charged in the liquid crystal capacitor Clc until the next data signal is charged.

The driving circuit unit 6 includes a gate driver 30 which generates a gate-on voltage according to the gate control signal GCS and sequentially supplies the gate-on voltages to the gate lines GL1 to GLn; A data driver 40 converting the input data Data into an image signal according to the data control signal DCS and supplying the data data to the corresponding data lines DL1 to DLm so as to be synchronized with the gate-on voltage; A timing controller for generating the gate control signal GCS, the data control signal DCS, the lamp dimming signal HDim, and the LED dimming signal BDim, and aligning the input data Data to the data driver 40 ( 20).

The gate driver 30 sequentially generates a gate-on voltage, that is, a gate high pulse, according to the gate control signal GCS from the timing controller 20, and sequentially supplies the gate-on voltages to the gate lines GL1 to GLn. The thin film transistor TFT is turned on in response to the gate-on voltage.

The data driver 40 converts the data RGB supplied from the timing controller 20 into an image signal, which is an analog signal, in accordance with the data control signal DCS supplied from the timing controller 20. ), One horizontal line is supplied to the data lines DL1 to DLm every one horizontal period to which the gate-on voltage is supplied. At this time, the data driver 40 inverts the polarity of the image signal supplied to the data lines DL1 to DLm in response to the polarity control signal.

As illustrated in FIG. 2, the timing controller 20 includes a control signal generator 22, a data aligner 24, and a backlight controller 26.

The control signal generator 22 drives the gate driver 30 using a synchronization signal input from the outside, that is, a dot clock DCLK, a data enable signal DE, and horizontal and vertical synchronization signals Hsync and Vsync. A gate control signal GCS for controlling timing and a data control signal DCS for controlling driving timing of the data driver 40 are generated.

The data aligning unit 24 aligns the input data Data so as to be suitable for driving the image display unit 2 and stores them in units of frames, and sequentially supplies the stored alignment data RGB of the one frame to the data driver 40. do.

As shown in FIG. 3, the backlight controller 26 generates the maximum gray scale detector 102, the adder 104, the comparator 106, the memory 108, the selector 110, and the dimming signal for each block. It is comprised including the part 112.

The maximum gray scale detection unit 102 for each block divides the image display unit 2 into a plurality of blocks and detects each of the maximum gray scales BG1 to BG9 among the input data Data supplied to each block on a frame basis. Hereinafter, it is assumed that the maximum gray scale detection unit 102 for each block divides the image display unit 2 into the first to ninth blocks B1 to B9 as shown in FIG. 4.

The adder 104 adds up the maximum grayscales BG1 to BG9 of each of the first to ninth blocks B1 to B9 supplied from the maximum gray scale detector 102 for each block to generate a totalized grayscale SG.

The comparison unit 106 compares each of the set first to ninth reference gradations Ref1 to Ref9 with the sum gradation gradations SG supplied from the adder 104 and compares the first to ninth as shown in Table 1 below. Generate signals CS1 to CS9.

Gradation Comparison signal Power Consumption Reference Dimming Curve for LED 0≤SG≤255 CS1 20W First reference dimming curve 256≤SG≤510 CS2 10W 2nd reference dimming curve 511≤SG≤765 CS3 7 W Third reference dimming curve 676≤SG≤1020 CS4 5 W 4th reference dimming curve 1021≤SG≤1275 CS5 4 W 5th reference dimming curve 1276≤SG≤1530 CS6 4 W 5th reference dimming curve 1531≤SG≤1785 CS7 3 W 6th reference dimming curve 1786≤SG≤2040 CS8 3 W 6th reference dimming curve 2041≤SG≤2295 CS9 2W 7th reference dimming curve

The memory unit 108 includes reference dimming curves RDim_cur1 to RDim_cur7 for the first to seventh LEDs set as shown in FIG. 5 to maintain a constant power consumption of the backlight 4 according to the sum gray scale SG. Is supplied to the selector 110. At this time, each of the reference dimming curves RDim_cur1 to RDim_cur7 for the first to seventh LEDs is set to correspond to the range of the sum gray scale SG as shown in Table 1. For example, the reference dimming curve RDim_cur1 for the first LED is set to have a power consumption of 20 W when the backlight 4 is driven at 100% dimming value, and the reference dimming curve RDim_cur2 for the second LED is set. When the backlight 4 is driven at a 100% dimming value, the backlight 4 is set to have a power consumption of 10W. Similarly, the reference dimming curve RDim_cur3 for the third LED is set to have a power consumption of 7 W, and the reference dimming curve RDim_cur4 for the fourth LED has a power consumption of 5 W. The reference dimming curve RDim_cur5 for the fifth LED is set to 4W, and the reference dimming curve RDim_cur6 for the sixth LED has a power consumption of the backlight 4. The reference dimming curve RDim_cur7 for the seventh LED is set to be 3W, and the power consumption of the backlight 4 is set to 2W.

In addition, the memory unit 108 supplies the dimming signal generator 112 with a reference dimming curve LDim_cur for driving the lamp according to the sum gray scale SG.

The selecting unit 110 may reference dimming curves RDim_cur1 to RDim_cur7 for the first to seventh LEDs supplied from the memory unit 108 according to the first to ninth comparison signals CS1 to CS9 supplied from the comparing unit 108. ) Is selected and supplied to the dimming signal generator 112. In this case, the selector 110 selects the reference dimming curve RDim_cur for the LED according to the comparison signal CS as shown in Table 1 below.

The dimming signal generator 112 may include a lamp dimming signal HDim and an LED dimming signal BDim corresponding to the maximum gray scales BG1 to BG9 of the blocks B1 to B9 supplied from the maximum gray scale detector 104 for each block. Is generated and supplied to the backlight driver 8. In this case, the dimming signal generator 112 generates the LED dimming signal BDim with reference to the reference dimming curve RDim_cur for LEDs selected and supplied by the selecting unit 110 and is supplied from the memory unit 108. The lamp dimming signal HDim is generated with reference to the reference lamp dimming curve LDim_cur.

In detail, the dimming signal generator 112 has the largest value among the maximum gray levels of each of the first to third blocks B1 to B3 supplied from the maximum gray level detector 104 for each block in the lamp reference dimming curve LDim_cur. The lamp dimming signal HDim1 in the first horizontal direction corresponding to the maximum gray scale having a maximum value, and has the largest value among the maximum gray scales of each of the fourth to sixth blocks B4 to B6 in the lamp reference dimming curve LDim_cur. Maximum gradation having the largest value among the maximum gradations of each of the seventh to ninth blocks B7 to B9 in the ramp dimming signal HDim2 in the second horizontal direction corresponding to the maximum gradation and the lamp reference dimming curve LDim_cur. The ramp dimming signal HDim3 in the third horizontal direction corresponding to the signal is generated and supplied to the backlight driver 8.

Also, the dimming signal generator 112 may include first to ninth blocks corresponding to each of the maximum gray levels of the blocks B1 to B9 supplied from the maximum gray level detector 104 for each block in the reference dimming curve RDim_cur for LEDs. Each of the LED dimming signals BDim1 to BDim9 is generated and supplied to the backlight driver 8.

In FIG. 1, the backlight driver 8 includes a lamp driver 120 and an LED driver 122 as shown in FIG. 6.

The lamp driver 120 corresponds to each of the first to third horizontal lamp dimming signals HDim1, HDim2, and HDim3 supplied from the dimming signal generator 112 by using an input power Vin input from the outside. Lamp driving voltages Vlamp1, Vlamp2, and Vlamp3 in the first to third horizontal directions are generated and supplied to the backlight 4.

The LED driver 122 corresponds to each of the LED dimming signals BDim1 to BDim9 of the first to ninth blocks supplied from the dimming signal generator 112 using an input power Vin input from the outside. The LED driving voltages Vled1 to Vled9 of the ninth block are generated and supplied to the backlight 4.

In FIG. 1, the backlight 4 includes a case 200, a plurality of lamps 210, a plurality of LED arrays 220, a diffusion plate 230, and a plurality of prism sheets 240 as shown in FIG. 7. , 250).

The case 200 accommodates the plurality of lamps 210 and the plurality of LED arrays 220 and emits heat generated from the plurality of lamps 210 and the plurality of LED arrays 220 to the outside.

The plurality of lamps 210 are arranged side by side to have a predetermined interval on the bottom surface of the case 200. Hereinafter, it is assumed that the plurality of lamps 210 is composed of nine.

Accordingly, the first to third lamps disposed on the upper part of the nine lamps 210 are turned on by the lamp driving voltage Vlamp1 in the first horizontal direction supplied from the backlight driving unit 8, so that the image display unit 2 The light is irradiated to the upper region of the. Further, the fourth to sixth lamps among the nine lamps 210 are turned on by the lamp driving voltage Vlamp2 in the second horizontal direction supplied from the backlight driver 8 so as to light in the middle region of the image display unit 2. Investigate The seventh to ninth lamps among the nine lamps 210 are turned on by the third horizontal lamp driving voltage Vlamp3 supplied from the backlight driving unit 8 to light the lower region of the image display unit 2. Investigate

The plurality of LED arrays 220 are disposed on the bottom surface of the case 200 corresponding to the adjacent lamps 210.

Each LED array 220 includes a plurality of LED packages 222 disposed to have a predetermined interval. The plurality of LED packages 222 are disposed in at least two LED arrays 220 disposed to face each of the blocks B1 to B9 of the image display unit 2 to correspond to the respective blocks B1 to B9. Light is emitted by the driving voltages Vled1 to Vled9 to irradiate light to the blocks B1 to B9 of the image display unit 2. That is, the plurality of LED packages 222 disposed in the at least two LED arrays 220 disposed to face the first block B1 of the image display unit 2 are connected to the first block from the backlight driver 8. Light is emitted by the LED driving voltage Vled1 to irradiate light to the first block B1 of the image display unit 2. Similarly, the plurality of LED packages 222 arranged in the at least two LED arrays 220 arranged to face the second block B2 of the image display unit 2 are similar to those of the second block from the backlight driver 8. Light is emitted by the LED driving voltage Vled2 to irradiate light to the second block B2 of the image display unit 2.

The diffusion plate 230 diffuses the light emitted from the plurality of lamps 210 and / or the plurality of LED packages 222 to correspond to the entire area of the image display unit 2.

The plurality of prism sheets 240 and 250 condense and irradiate the image display unit 2 so that the light diffused by the diffusion plate 130 proceeds in a direction perpendicular to the image display unit 2.

Such a backlight 4 is the upper region, the middle region and the lower portion of the image display portion 2 according to the lamp driving voltages Vlamp1, Vlamp2, Vlamp3 in the first to third horizontal directions supplied from the backlight driver 8. The light is irradiated to the area, and the light is irradiated to the first to ninth blocks B1 to B9 of the image display unit 2 according to the LED driving voltages Vled1 to Vled9 of the first to ninth blocks.

The driving apparatus and driving method of the liquid crystal display according to the exemplary embodiment of the present invention as shown in FIG. 8A show a spot image on the image display unit 2 as shown in FIG. 8B. As shown in the image display unit 2 by driving the plurality of LED packages 222 disposed opposite to the fourth to sixth lamps 210 and the fifth block B5 according to the maximum gray scale of the fifth block B5. The partial luminance of the spot image is emphasized.

In addition, the driving apparatus and the driving method of the liquid crystal display according to the embodiment of the present invention, in the case of displaying a dark image on the image display unit 2, as shown in Figure 9a, as shown in Figure 9b And a plurality of LED packages 222 disposed to face the first to third lamps 210 and the first and second blocks B1 and B2 according to a larger maximum gray level of the second blocks B1 and B2. Image) by driving the plurality of LED packages 222 disposed opposite to the sixth and eighth blocks B6 and B8 according to the maximum gray level of each of the sixth and eighth blocks B6 and B8. Emphasize the partial luminance of the bright parts in the dark image shown in (2).

In addition, in the case of displaying a bright image on the image display unit 2 as shown in FIG. 10A, a driving apparatus and a driving method of the liquid crystal display according to an exemplary embodiment of the present invention may include a first device as shown in FIG. 10B. To each block B1 and the lamps 210 disposed in the horizontal direction according to the largest gray scale among the largest gray scales of the blocks B1 to B3, B4 to B6, and B7 to B9 in the third horizontal direction. To a plurality of LED packages 222 disposed opposite to each of the blocks B1 to B9 in accordance with the maximum gradation of B-9 to B9 to maintain brightness in a bright image displayed on the image display unit 2 and consume power at the same time. Decreases.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Will be apparent to those of ordinary skill in the art.

The driving apparatus and driving method of the liquid crystal display according to the embodiment of the present invention as described above divides an image of one frame into a plurality of blocks and drives each lamp and each LED array according to the sum of the maximum gray levels of each block. Thus, the power consumption can be kept constant at all times regardless of the image displayed on the image display unit. In addition, the present invention can emphasize partial luminance of an image by dividing each LED array arranged opposite to each block of the image display unit.

Claims (21)

An image display unit including a liquid crystal cell formed for each region defined by a plurality of gate lines and a plurality of data lines; A backlight for irradiating light to the image display unit by using a plurality of LED arrays having a plurality of lamps arranged side by side and a plurality of LEDs (Light Emitting Diodes) disposed between the lamps; A driving circuit unit which displays input data from the outside on the image display unit, divides the image display unit into a plurality of blocks, and generates a plurality of lamp dimming signals and a plurality of LED dimming signals according to the sum of the maximum gray scales for each block; And a backlight driver for driving the backlight according to the lamp dimming signal and the LED dimming signal. The method of claim 1, The driving circuit unit, A gate driver supplying a gate-on voltage to the gate line; A data driver converting the input data into an image signal and supplying the input data to a corresponding data line in synchronization with a gate-on voltage; And a timing controller configured to generate the lamp dimming signals and the LED dimming signals and to align the input data to supply the data dimming signals to the data driver. The method of claim 2, The timing controller, A control signal generator for generating a control signal for controlling the gate driver and the data driver by using a synchronization signal from an outside; A data alignment unit for arranging the input data and storing the input data in a frame unit, and sequentially supplying the stored alignment data of the one frame to the data driver; And a backlight controller configured to generate the lamp dimming signals and the LED dimming signals. The method of claim 3, wherein The backlight control unit, A maximum gray level detection unit for each block which divides the image display unit into a plurality of blocks and detects the maximum gray level for each block; A summation unit for generating a summation gray level of the maximum gray level for each block; A comparator configured to generate a comparison signal by comparing the first to i th reference grayscales set to correspond to the number of blocks with the sum grayscales; A memory unit storing a plurality of reference dimming curves for LEDs and reference dimming curves for lamps set to maintain a constant power consumption of the backlight according to the sum gray scale; A selection unit for selecting one of a plurality of reference dimming curves for the LEDs provided from the memory unit according to the comparison signal; A dimming signal for generating the lamp dimming signals and the LED dimming signals corresponding to the maximum gray level for each block by referring to the reference dimming curve for the LED selected by the selection unit and the lamp reference dimming curve provided from the memory unit. The driving device of the liquid crystal display device comprising a generation unit. 5. The method of claim 4, Wherein each of the first to i-th reference gray scales corresponds to j × 2 ^N (where j is the first to i and N is the number of bits of the input data). 6. The method of claim 5, And the reference dimming curves for the plurality of LEDs are set to have different values. The method of claim 6, Each of the plurality of reference dimming curves for LEDs is configured to be different from each other so that the power consumption of the backlight is constant even if the number of driving of each block is changed. 5. The method of claim 4, The dimming signal generator, Generating a lamp dimming signal in each horizontal direction according to the largest gray scale among the maximum grays of the blocks in each horizontal direction opposite to the lamps in at least two units in the lamp reference dimming curve; And a LED dimming signal of each block in the reference dimming curve for the LED selected by the selection unit according to the maximum gray level of each block. 9. The method of claim 8, The backlight driving unit drives the lamps arranged in the at least one horizontal direction according to the lamp dimming signals in each horizontal direction, and the LEDs arranged in the at least one block according to the LED dimming signals of the respective blocks. A drive device for a liquid crystal display device, characterized in that for driving. 9. The method of claim 8, The backlight driving unit drives the lamps arranged in the horizontal direction and the LEDs arranged in the respective blocks simultaneously according to the lamp dimming signals in the horizontal directions and the LED dimming signals in the blocks. Drive of the device. 11. The method according to claim 9 or 10, The backlight drive unit, A lamp driver for generating lamp driving voltages in the horizontal directions corresponding to the lamp dimming signals in the horizontal directions to drive lamps in the at least two units arranged in the horizontal directions; And an LED driver for generating the LED driving voltage of each block corresponding to the LED dimming signal of each block to drive the LEDs arranged in each block. The method of claim 1, The back light, A case accommodating the plurality of lamps and the plurality of LED arrays disposed between the lamps; A diffusion plate covering the case and diffusing light from the lamp and the LED array to correspond to the entire area of the image display unit; And a plurality of prism sheets stacked on the diffuser plate and condensing light passing through the diffuser plate to irradiate the image display unit. In the driving method of a liquid crystal display device comprising an image display unit having a liquid crystal cell formed for each region defined by a plurality of gate lines and a plurality of data lines, A first step of dividing the image display unit into a plurality of blocks and generating a plurality of lamp dimming signals and a plurality of LED dimming signals according to the sum of the maximum gray scales for each block; A second step of driving a backlight composed of a plurality of lamps arranged side by side and a plurality of LED arrays each having a plurality of LEDs arranged between the lamps according to the lamp dimming signals and the LED dimming signals; And a third step of supplying an image signal corresponding to input data to the image display unit. 14. The method of claim 13, In the first step, A first step of storing a plurality of reference dimming curves for LEDs and reference dimming curves for lamps set to maintain a constant power consumption of the backlight according to the sum gray scales in a memory unit; Dividing the image display unit into a plurality of blocks and detecting a maximum gradation for each block; Generating a summated gray level of the maximum gray level for each block; A first to fourth step of generating a comparison signal by comparing the first to i th reference grayscales set to correspond to the number of blocks with the sum gray scales; Selecting one of a plurality of reference dimming curves for the LEDs provided from the memory unit according to the comparison signal; Steps 1 through 6 of generating the lamp dimming signals and the LED dimming signals corresponding to the maximum gray level for each block by referring to the selected reference dimming curve for the LED and the lamp reference dimming curve provided from the memory unit. Method of driving a liquid crystal display device comprising a. 15. The method of claim 14, Wherein each of the first to i-th reference gray scales corresponds to j × 2 ^N (where j is the first to i and N is the number of bits of the input data). 16. The method of claim 15, And the reference dimming curves for the plurality of LEDs are set to have different values. 17. The method of claim 16, And the reference dimming curves for the plurality of LEDs are set differently so that the power consumption of the backlight is constant even if the number of driving of each of the blocks changes. 15. The method of claim 14, Step 1-6, Generating a lamp dimming signal in each horizontal direction according to the largest gray scale among the maximum grays of the blocks in each horizontal direction opposite to the lamps in at least two units in the lamp reference dimming curve; And driving the LED dimming signal of each block in the selected reference dimming curve for the LED according to the maximum gray level of each block. The method of claim 18, The second step, Generating lamp driving voltages in the horizontal directions corresponding to the lamp dimming signals in the horizontal directions to drive lamps in the at least two units arranged in the horizontal directions; And driving the LEDs arranged in the respective blocks by generating the LED driving voltages of the respective blocks corresponding to the LED dimming signals of the respective blocks. 20. The method of claim 19, The second step drives the lamps arranged in the at least one horizontal direction according to the lamp dimming signals in each horizontal direction and the LEDs arranged in the at least one block according to the LED dimming signals of the respective blocks. A driving method of a liquid crystal display device, characterized in that for driving. 20. The method of claim 19, In the second step, the lamps arranged in the horizontal direction and the LEDs arranged in the respective blocks are simultaneously driven according to the lamp dimming signals in the horizontal directions and the LED dimming signals in the blocks. Method of driving the device.

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