KR101502367B1 - Back light unit and liquid crystal display device using the same and driving method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit, and more particularly, to a backlight unit that can improve display quality of an image by compensating for a difference in color perception with respect to light generated from a backlight, Driving method.

To this end, the backlight unit according to the embodiment of the present invention includes an inverter controller for compensating at least one of chrominance and luminance values from the outside for an external dimming control signal to generate a PWM signal; An inverter for generating an AC drive signal in response to the PWM signal; And a backlight for generating light according to the AC drive signal and detecting at least one of a chromaticity and a luminance value of the generated light and supplying the detected value to the inverter control unit .

Backlight unit, LED module, R, G, B_LED, photo sensor module, photo sensor,

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE USING THE SAME AND DRIVING METHOD THEREOF BACKGROUND OF THE INVENTION [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit, and more particularly, to a backlight unit that can improve display quality of an image by compensating for a difference in color perception with respect to light generated from a backlight, Driving method.

BACKGROUND ART Demands for video display devices have been increasing in various forms as an information society has developed. In recent years, a liquid crystal display, a field emission display, a plasma display panel, Various flat panel display devices such as a light emitting display are utilized.

In the liquid crystal display device, the amount of light supplied from a backlight unit is controlled by a liquid crystal panel having a plurality of liquid crystal cells arranged in a matrix form to display a desired image. Specifically, a liquid crystal display device obtains a desired image by forming an electric field in a liquid crystal layer according to a data signal to adjust transmittance of light passing through the liquid crystal layer.

The backlight unit includes a backlight having a plurality of light sources for generating light, an inverter for driving each light source provided in the backlight, and an inverter driving circuit. Such a backlight can be divided into an edge type and a direct-type backlight depending on the position of each light source.

However, in the conventional edge type and direct type backlight, a plurality of light sources are accommodated in a bottom case and driven. In this case, light is generated according to the arrangement direction of the light sources and the difference in distance between the respective light sources and the bottom case Brightness and chromaticity are different for each region. Particularly, when a light emitting diode (LED) is used as a light source, the red (R), green (G), and blue (B) LEDs are sequentially arranged so that the chromaticity and luminance .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a backlight unit for compensating for the difference in color per region for light generated from a backlight, And a driving method thereof.

According to another aspect of the present invention, there is provided a backlight unit including: an inverter control unit for generating a PWM signal by compensating at least one of a chrominance value and a luminance value from an exterior to a dimming control signal from the outside; An inverter for generating an AC drive signal in response to the PWM signal; And a backlight for generating light according to the AC drive signal and detecting at least one of a chromaticity and a luminance value of the generated light and supplying the detected value to the inverter control unit .

According to another aspect of the present invention, there is provided a method of driving a backlight unit, including the steps of generating a PWM signal by compensating at least one of a chrominance value and a luminance value from an external source, ; Generating an AC drive signal in response to the PWM signal; And generating light according to the AC drive signal and detecting at least one of a chromaticity and a luminance value of the generated light and outputting the detected value.

According to another aspect of the present invention, there is provided a liquid crystal display device including: a liquid crystal panel including a plurality of pixels; A gate and a data driver driving the plurality of pixels; A timing controller for supplying image data input from the outside to the gate and the data driver, and controlling the gate and the data driver; And a backlight unit having the above-described characteristics for irradiating light to the liquid crystal panel.

According to another aspect of the present invention, there is provided a method of driving a liquid crystal display device including a liquid crystal panel having a plurality of pixels and a liquid crystal display device having a backlight unit for irradiating the liquid crystal panel with light, The method comprising: displaying an image by adjusting a transmittance of light; And a driving method of the above-described backlight unit for irradiating light to the liquid crystal panel.

The backlight unit according to the present invention can compensate for the difference in color hue for each region with respect to light generated from the backlight so that light having at least one of luminance and chromaticity from the backlight can be generated.

Accordingly, the liquid crystal display device using the backlight unit of the present invention can display the image by receiving light from at least one of the luminance and the chromaticity from the backlight, thereby improving the display quality of the image.

A backlight unit according to an embodiment of the present invention having the above characteristics, a liquid crystal display using the same, and a driving method thereof will be described in more detail with reference to the accompanying drawings.

1 is a block diagram illustrating a backlight unit and a liquid crystal display using the same according to an embodiment of the present invention. 2 is a configuration diagram showing a backlight unit according to the first embodiment of the present invention.

The backlight unit 10 shown in FIG. 1 and FIG. 2 compensates for the dimming value control signal input from the outside, that is, the chrominance and luminance values input from the outside to the dimming control signal Dim, An inverter 16 for generating an AC drive signal ADS in response to a PWM signal from the inverter control unit 14 and a plurality of light sources And a backlight 12 for generating light in accordance with the AC drive signal ADS.

The backlight unit 10 of the present invention includes the photosensor 24 and the detection unit 26 and detects at least one of the chromaticity and luminance values of the light generated from the backlight 12 for each of a plurality of areas , And a photodetector (22) for supplying at least one of the detected chromaticity values and luminance values to the inverter control unit (14). Here, the photodetector 22 may be a general colorimeter and luminance meter, and the photodetector 22 is attached to the outside of the backlight unit 10 so as to be connected to the inverter control unit 14. Then, the photodetector 22 can be detached from the inverter control unit 12 after the chromaticity and luminance values of the light generated from the backlight 12 are detected.

The backlight unit 10a shown in Fig. 2 has a structure in which the central region CD of the direct-type LED backlight 12a and both outer regions SD1, and SD2 of the first and second color components. At this time, the inverter control unit 14 controls the plurality of inverters 16 and a plurality of PWMs (not shown) for driving the plurality of inverters 16 and corresponding LED driving units (not shown) according to at least one value of the chromaticity and luminance values inputted from the photo- It is possible to generate a signal by varying it. The operation of the backlight unit 10 and the method of generating the PWM signal will be described more specifically with reference to the accompanying drawings.

1 includes a liquid crystal panel 2 formed with a plurality of pixels, a data driver 4 for driving a plurality of data lines DL1 to DLm, a plurality of gate lines GL1 to GLn, A timing controller 8 for supplying image data RGB inputted from the outside to the data driver 4 and controlling the data driver 4 and the gate driver 6, The backlight unit 10 according to the embodiment of the present invention as described above is provided.

The liquid crystal panel 2 includes a thin film transistor (TFT) formed in each pixel region defined by a plurality of gate lines GL1 to GLn and a plurality of data lines DL1 to DLm, And a capacitor Clc. The liquid crystal capacitor Clc is composed of a pixel electrode connected to the TFT and a common electrode facing the pixel electrode with the liquid crystal therebetween. The TFT supplies a data signal from each of the data lines DL1 to DLm to the pixel electrode in response to a scan pulse from each of the gate lines GL1 to GLn. The liquid crystal capacitor Clc charges the difference voltage between the data signal supplied to the pixel electrode and the common voltage supplied to the common electrode, adjusts the arrangement of the liquid crystal molecules according to the difference voltage, and adjusts the light transmittance to implement the gradation. The storage capacitor Cst is connected in parallel to the liquid crystal capacitor Clc so that the voltage charged in the liquid crystal capacitor Clc is maintained until the next data signal is supplied. The storage capacitor Cst is formed by overlapping the pixel electrode with the previous gate line sandwiched by the insulating film. Alternatively, the storage capacitor Cst may be formed by overlapping the pixel electrode with the storage line and the insulating film interposed therebetween.

The data driver 4 converts the digital video data Data into analog video signals in accordance with the data control signal DCS from the timing controller 8 and supplies the analog video signals to the gate lines GL1 to GLn, An analog video signal for one horizontal line is supplied to each of the data lines DL1 to DLm for each horizontal period. That is, the data driver 4 selects a gamma voltage having a predetermined level according to the gradation value of the analog video signal and supplies the selected gamma voltage to each of the data lines DL1 to DLm.

The gate driver 6 sequentially generates a scan pulse, for example, a gate high pulse in response to the gate control signal GCS from the timing controller 8, and sequentially supplies the gate pulse to each of the gate lines GL1 to GLn.

The timing controller 8 arranges image data (RGB) from the outside so as to be suitable for driving the liquid crystal panel 2 and supplies it to the data driver 4. [ The data driver 4 and the gate driver 6 are controlled by generating a gate control signal GCS and a data control signal DCS using synchronous signals DCLK, DE, Hsync and Vsync from the outside . The timing controller 8 generates a dimming control signal Dim using external synchronization signals DCLK, DE, Hsync and Vsync and image data RGB and outputs the dimming control signal Dim to the backlight unit 10, .

The backlight 12a includes a plurality of light sources for generating light. Here, the light source may be an external electrode fluorescent lamp (EEFL), a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), a light emitting diode (LED) ) May be used. These lamps can be driven by the AC voltage from the inverter 16, that is, the AC drive signal ADS, to generate light. Hereinafter, a direct-type LED backlight 12a using a plurality of red (R), green (G) and blue (B) LEDs (hereinafter referred to as R_LED, G_LED, and B_LED) do.

The inverter control unit 14 compensates the chrominance and luminance values inputted from the photodetector 22 to the dimming control signal Dim supplied from the external system or the timing controller 8 to control the plurality of inverters 16 and the corresponding LEDs And generates a plurality of PWM signals for driving a driving unit (not shown). For this purpose, the inverter control unit 14 varies the duty ratio of the PWM signal, that is, the ratio of the high signal in one period, according to at least one of the chromaticity and luminance values input from the photodetector 22, The inverter control IC 18 for generating a signal and the duty ratio Duty of the PWM signal varying from the inverter control IC 18 or supplying the duty ratio of the PWM signal stored in advance to the inverter control IC 18 And a memory 20.

The inverter control IC 18 of Fig. 2 controls at least one of the chromaticity values and luminance values of the central region CD of the direct-type LED backlight 12a and both outer regions SD1 and SD2 from the photodetector 22 sequentially . The duty ratio Duty of the PWM signal is set so that at least one of the chromaticity values and luminance values of both the outer areas SD1 and SD2 becomes equal to each other based on at least one of the chromaticity and luminance values of the central area CD. Is repeatedly adjusted and set. Then, the duty ratio (Duty) of the set PWM signal is supplied to the memory 20 made up of a plurality of look-up tables or the like. As such inverter control IC 18, an IC such as BD9766FV or BD9897FV may be used.

Specifically, since a plurality of R_LEDs, G_LEDs, and B_LEDs are sequentially arranged in the direct-type LED backlight 12a, the color saturation of red (R) arranged in a row is largely displayed in one outer area SD1. Then, the color of blue (B) arranged in a row is largely displayed in the outer area SD2 of the other side. Therefore, the inverter control IC 18 controls each PWM (pulse width modulation) so that at least one of the chromaticity and luminance values of the central region CD repeatedly input from the photodetector 22 and the both outer regions SD1 and SD2 becomes equal The duty ratio (Duty) of the signal is repeatedly adjusted. The duty ratio Duty at the time when at least one of the chromaticity values and the luminance values of the central region CD and both outer regions SD1 and SD2 becomes equal is transmitted to the memory 20 and stored. Thereafter, when the photodetector 22 is detached and the backlight unit 10a is constituted and driven by the liquid crystal display device, the inverter control IC 18 generates a plurality of And supplies the generated PWM signal to each inverter 16 and the corresponding LED driver.

Each of the inverters 16 and the corresponding LED driver generates an AC drive signal ADS in response to each PWM signal input from the inverter control IC 18 and drives the plurality of R_LED, G_LED, and B_LED To the respective LED modules (not shown). In other words, each inverter 16 adjusts the supply time, amplitude, or pulse width of the AC drive signal ADS supplied to each LED module so as to correspond to each PWM signal to be inputted and outputs it. At least one LED module may be connected to each of the inverters 16 and the corresponding LED driver, and the number of LED modules connected to each inverter 16 is determined in consideration of a voltage drop in the vicinity of the LED module . Each of the LED modules may be provided with a plurality of R_LED, G_LED, and B_LED connected in series or parallel, an LED block, and a switching circuit. On the other hand, the inverter 16 compensates the feedback voltage or the current FI from the backlight 12a to generate the AC drive signal ADS.

FIG. 3 is another configuration diagram showing a backlight unit according to the first embodiment of the present invention.

The backlight unit 10b shown in Fig. 3 includes a center region CD of the edge-type LED backlight 12b and a center region CD of both edge regions 12b without the liquid crystal panel 2 on the edge- SD1, and SD2 of the first and second color components. At this time, the inverter control unit 14 varies a plurality of PWM signals for driving the plurality of inverters 16 and the corresponding LED driving units according to at least one value of the chromaticity and luminance values inputted from the photodetector 22 Respectively.

The inverter control IC 18 of FIG. 3 receives at least one of the chromaticity and luminance values of the center region CD of the edge-type LED backlight 12b and both outer regions SD1 and SD2 from the photodetector 22 Are sequentially supplied repeatedly. The duty ratio Duty of the PWM signal is set so that at least one of the chromaticity values and luminance values of both the outer areas SD1 and SD2 becomes equal to each other based on at least one of the chromaticity and luminance values of the central area CD. Is repeatedly adjusted and set. Then, the duty ratio (Duty) of the set PWM signal is supplied to the memory 20 made up of a plurality of look-up tables or the like.

Specifically, since the plurality of R_LEDs, G_LEDs, and B_LEDs are sequentially arranged at the edge portions of the backlight 12b, the edge-type LED backlights 12b are provided with the R_LEDs formed at the outermost region in one outer- The color tone of red (R) becomes large. In addition, the color of the blue (B) is largely displayed due to the B_LEDs formed in the outermost region in the outer area SD2 of the other side. Therefore, the inverter control IC 18 controls each PWM signal (PWM signal) so that at least one of the chromaticity and luminance value of the central region CD repeatedly input from the photodetector 22 and the both outer regions SD1, The duty ratio (duty) The duty ratio Duty at the time when at least one of the chromaticity values and the luminance values of the central region CD and both outer regions SD1 and SD2 becomes equal is transmitted to the memory 20 and stored. Thereafter, when the photodetector 22 is detached and the backlight unit 10b is formed in a liquid crystal display or the like, the inverter control IC 18 generates a plurality of And supplies the generated PWM signal to each inverter 16 and the corresponding LED driver.

Fig. 4 is a configuration diagram showing a backlight unit according to a second embodiment of the present invention.

The backlight unit 10c shown in Fig. 4 includes a backlight unit 12c and a backlight unit 12b that are provided in the dimming control signal Dim input from the timing controller 8 or the external system, among the chromaticity values UV and luminance Y An inverter 16 for generating an AC drive signal ADS in response to a PWM signal from the inverter control unit 14, and a plurality of light sources (12) for generating at least one of the chromaticity (UV) and luminance (Y) values of the generated light in accordance with the AC driving signal (ADS) and supplying the detected value to the inverter control unit Respectively.

The backlight unit 10c is provided on the edge-type LED backlight 12c with the center region of the edge-type LED backlight 12c with and without the liquid crystal panel 2, And detecting a value of at least one of the values. At this time, the inverter control unit 14 controls the plurality of inverters 16 and corresponding LED driving units (not shown) according to at least one value of the chromaticity (UV) and luminance (Y) values inputted from the edge type LED backlight 12c And a plurality of PWM signals for driving the plurality of PWM signals.

The edge type LED backlight 12c is further provided with at least one sensor module PS_Dm to face at least one LED module LED_Dm. Specifically, the edge type LED backlight 12c is provided with a sensor module PS_Dm (PS_Dm) having a plurality of photosensors PS1 to PSn at positions corresponding to the LED modules LED_Dm in which a plurality of R_LED, G_LED, and B_LED are arranged. Is formed. The sensor module PS_Dm supplies at least one of the values of the chromaticity (UV) and the luminance (Y) detected from the plurality of photosensors PS1 to PSn to the inverter control unit 14.

The inverter control IC 18 of FIG. 4 is repeatedly supplied with at least one of the values of the chromaticity (UV) and luminance (Y) detected from the plurality of photosensors PS1 to PSn. At least one value of the chromaticity or luminance value from the photosensors located in the central region, for example, the fourth to the (n-3) th photosensors (PS4 to PSn-3) The duty ratio Duty of the PWM signal is repeatedly set so as to be equal to at least one of the chromaticity or luminance value from the photoelectric sensors PS1 to PS3 and the n-2 to nth photo sensors PSn-2 to PSn. . Thereafter, the duty ratio Duty of the set PWM signal is supplied to the memory 20 composed of a plurality of look-up tables and the like, and the generated PWM signal is supplied to the inverter 16.

Specifically, since the plurality of R_LED, G_LED, and B_LED are sequentially arranged at the edge portions of the backlight 12c, the edge type LED backlight 12c of FIG. The color tone of the color image R is largely displayed. In addition, the color of the blue color (B) becomes large due to the B_LED of the outermost side of the other side in the outer area of the other side. Accordingly, the inverter control IC 18 receives at least one value of the chromaticity and luminance values repeatedly detected from the plurality of photosensors PS1 to PSn, and outputs the chromaticity and luminance values inputted from the plurality of photosensors PS1 to PSn The duty ratio (Duty) of each PWM signal is repeatedly adjusted.

For example, the inverter control IC 18 determines that the average value of at least one of the chromaticity and luminance values detected from the 4th to (n-3) th photosensors (PS4 to PSn-3) The duty of the PWM signal is set to be equal to the average value of at least one of the chromaticity and the luminance value detected from the first photosensor (PS1 to PS3) and the (n-2) th to Duty can be repeatedly adjusted and set. The inverter control IC 18 also controls the first photosensor PS1 and the nth photosensor PS1, which are located at the outermost regions, respectively, in which the average value of the luminances detected from the second through the (n-1) th photosensors PS2 through PSn- The duty ratio Duty of the PWM signal may be repeatedly adjusted and set so as to be equal to the brightness value detected by the sensor PSn.

Each inverter 16 and its corresponding LED driver generates an AC drive signal ADS corresponding to each PWM signal input from the inverter control IC 18 and generates an AC drive signal ADS) to drive the respective R_LED, G_LED, and B_LED. In other words, each of the inverters 16 and the corresponding LED driver supplies the supply time, amplitude, or pulse width of the AC drive signal ADS supplied to each LED module LED_Dm to correspond to each PWM signal inputted thereto And outputs it. The inverter 16 also compensates the feedback voltage or the current FI from the backlight 12c to generate the AC drive signal ADS.

5 is a flowchart for explaining the driving method of the backlight unit shown in FIG.

A driving method of the backlight unit 10c according to the second embodiment of the present invention will be described in more detail with reference to FIG.

First, the inverter control IC 18 of the present invention generates a PWM signal in accordance with the dimming control signal (Dim) from the external system or the timing controller 8 and supplies it to the inverter 16. Each of the inverters 16 and the corresponding LED driver generates an AC drive signal ADS corresponding to the PWM signal and supplies the AC drive signal ADS to the LED module LED_Dm of the backlight 12c to generate a plurality of R_LED, G_LED, and B_LED (ST1)

Then, when each of R, G, and B_LED is driven, the sensor module PS_Dm provided with the plurality of photosensors PS1 to PSn detects the chromaticity (UV) and luminance (brightness) detected from the photosensors PS1 to PSn Y) value to the inverter control IC 18. (ST2)

The inverter control IC 18 receives at least one value of the chromaticity (UV) and luminance (Y) values detected from the photosensors PS1 to PSn through the sensor module PS_Dm, It is determined whether or not at least one of the values of the chromaticity (UV) and the luminance (Y)

Specifically, when at least one of the values of the chromaticity (UV) and the luminance (Y) input from the photosensors PS1 to PSn is not equal to each other, the inverter control IC 18 controls the photosensors PS1 to PSn, The duty ratio Duty of each PWM signal is repeatedly adjusted so that at least one of the values of the chromaticity (UV) and the luminance (Y)

On the other hand, the inverter control IC 18 controls the first photosensor PS1 and the second photosensor PS2, in which the average value of the luminance detected from the second to the (n-1) th photosensors PS2 to PSn- the duty ratio Duty of the PWM signal may be repeatedly adjusted so as to be equal to the luminance value detected by the photo sensor PSn.

As described above, when at least one of the values of the chromaticity (UV) and the luminance (Y) input from the photo sensors PS1 to PSn becomes equal to each other, the inverter control IC 18 outputs the PWM signal duty ratio (ST4). Then,

Each of the inverters 16 and the LED driver corresponding thereto generates an AC drive signal ADS corresponding to the PWM signal generated from the inverter control IC 18 according to the duty ratio stored in the memory 20 And supplies the generated AC drive signal ADS to the LED module LED_Dm to drive each of R_LED, G_LED, and B_LED.

As described above, the backlight unit 10 according to the first and second embodiments of the present invention compensates for the difference in color hue between the light generated from the backlight 12 and the luminance of light generated in each region And at least one of the chromaticity can be made equal. Accordingly, the liquid crystal display device using the backlight unit 10 of the present invention can display images by receiving light having at least one of luminance and chromaticity from the backlight 12, thereby improving the display quality of the image .

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Will be clear to those who have knowledge of.

1 is a configuration diagram illustrating a backlight unit and a liquid crystal display device using the same according to an embodiment of the present invention.

2 is a configuration diagram showing a backlight unit according to the first embodiment of the present invention.

3 is a diagram showing another configuration of a backlight unit according to the first embodiment of the present invention.

4 is a configuration diagram illustrating a backlight unit according to a second embodiment of the present invention;

5 is a flowchart for explaining a driving method of the backlight unit shown in Fig.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

2: liquid crystal panel 4: data driver

6: Gate driver 8: Timing controller

10: Backlight unit 12: Backlight

14: inverter control unit 16: inverter

18: inverter control IC 20: memory

22: photodetector 24: photo sensor

26: Detector PWM signal: Pulse width modulation signal

ADS: AC drive signal PS_Dm: Photo sensor module

PS1 to PSn: first to nth photosensors

R, G, and B_LED: red, green, and blue light emitting elements

Claims (10)

 An inverter controller for compensating at least one of a chrominance and a luminance value from the outside to a dimming control signal from the outside to generate a PWM signal; An inverter for generating an AC drive signal in response to the PWM signal; And And a backlight for generating light in accordance with the AC driving signal and detecting at least one of a chromaticity and a luminance value of the generated light and supplying the detected value to the inverter control unit, The backlight At least one LED module in which a plurality of R, G, and B_LEDs are sequentially arranged, and a plurality of photo sensors are formed facing each of the R, G, and B LEDs, And at least one sensor module for supplying at least one value of the luminance values to the inverter control unit, The inverter control unit includes: Wherein at least one of the chromaticity and luminance values detected from the plurality of photosensors is repeatedly supplied to the photo sensors, An inverter control IC for repeatedly adjusting and setting the duty ratio of the PWM signal such that at least one of the chromaticity and luminance values detected from the photosensors formed in the outer region of the backlight becomes equal, And a memory for storing a duty ratio of the set PWM signal and supplying the duty ratio of the set PWM signal to the inverter control IC. delete delete delete delete A liquid crystal panel formed with a plurality of pixels; A gate and a data driver driving the plurality of pixels; A timing controller for supplying image data input from the outside to the gate and the data driver, and controlling the gate and the data driver; And The liquid crystal display device according to claim 1, further comprising a backlight unit according to claim 1 for emitting light to the liquid crystal panel. Generating a PWM signal by compensating at least one of a chrominance and a luminance value from the outside to a dimming control signal from the outside; Generating an AC drive signal in response to the PWM signal; And Generating a light according to the AC drive signal, and detecting and outputting at least one of a chromaticity and a luminance value of the generated light, The step of generating the PWM signal Generating the PWM signal such that at least one value of the chromaticity and luminance values detected in the outer region of the backlight is equal to at least one of the chromaticity and luminance values detected in the central region of the backlight, The PWM signal generation step At least one of the chromaticity and luminance values detected from the plurality of photosensors formed in the backlight is repeatedly supplied, and at least one of the chromaticity and luminance values of the light generated from the backlight is detected for each of the plurality of regions; And The duty ratio of the PWM signal is adjusted so that at least one of the chromaticity and luminance values detected in the outer region is equal to at least one of the chromaticity and luminance values detected in the central region among the plurality of regions The method of claim 1, further comprising: delete delete A method of driving a liquid crystal display device including a liquid crystal panel having a plurality of pixels and a backlight unit for emitting light to the liquid crystal panel, Adjusting an optical transmittance to display an image; And The method of driving a liquid crystal display device according to claim 7, further comprising the driving method of claim 7 for irradiating light to the liquid crystal panel.

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