KR100389026B1 - Apparatus and method for driving backlight of liquid crystal display device - Google Patents

Abstract

The present invention relates to a backlight driving apparatus and method for a liquid crystal display device that can sequentially flash by color using a synchronization signal three times the synchronization signal used in the liquid crystal panel.

The present invention relates to a red light source for irradiating red light to a liquid crystal panel, a green light source for irradiating green light to a liquid crystal panel, a blue light source for irradiating blue light to a liquid crystal panel, and a frequency of a reference vertical synchronization signal and a horizontal synchronization signal. A frequency multiplier for multiplying by a predetermined multiple, a timing controller for generating a timing signal instructing the timing of blinking the red light source, the green light source and the blue light source by the multiplied vertical synchronization signal and the horizontal synchronization signal, and a red light source and a green light source And a light source selection unit for generating a light source selection signal for selecting any one of the flashing timing signals of the blue light source, a light source driver for generating a drive signal for driving the red light source, the green light source and the blue light source, and a light source selection signal. Supplying the drive signal from the light source driver to any one of the red, green and blue light sources A switch element is provided.

With such a configuration, the backlight driving device of the liquid crystal display device of the present invention can be easily applied even when the frame frequency is changed because the synchronization signal supplied to the liquid crystal panel is used.

Description

Backlight driving device and method for liquid crystal display device {APPARATUS AND METHOD FOR DRIVING BACKLIGHT OF LIQUID CRYSTAL DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a backlight driving device and a method of a liquid crystal display device which can sequentially flash by color using a synchronization signal three times the synchronization signal used in a liquid crystal panel.

In general, liquid crystal displays (hereinafter referred to as "LCDs") have tended to be gradually widened due to their light weight, thinness, and low power consumption. According to this trend, LCD is being used for office automation equipment, audio / video equipment, and the like. On the other hand, the LCD is controlled to display the desired image on the screen by adjusting the transmission amount of the light beam according to the image signal applied to the plurality of control switches arranged in a matrix form.

Referring to FIG. 1, a conventional sequentially flickering liquid crystal display device is disposed on the rear side of the liquid crystal display element 11 to emit light of red (R), green (G), and blue (B) light. 13G, 13B, a liquid crystal driver 15 for causing the liquid crystal display element 11 to display an image, and a light source driver 17 for controlling the lighting of the light sources 13R, 13G, 13B.

The liquid crystal display element 11 is composed of a ferroelectric liquid crystal capable of high-speed response, and displays monochrome gray scales. The liquid crystal display element 11 is disposed with the liquid crystal cell 126 formed between the upper and lower substrates 101 and 102 with the liquid crystal 121 interposed therebetween, and the liquid crystal cell 126 as shown in the cross-sectional view of FIG. 2. A pair of polarizing plates 123 and 124 are further provided.

On the inner surface of the lower substrate 101, transparent pixel electrodes 103, first and second thin film transistors 104 and 105, and a capacitor 106 for sample holding are formed. On one side of the lower substrate 101, a gate line 112, a batch writing line 111, and a common line 113 are wired between rows of the pixel electrode 103, and a data line between columns of the pixel electrode 103. 114 is wired.

As shown in FIG. 3, the source terminal of the first thin film transistor 104 is connected to the pixel electrode 103, and the drain terminal is connected to one end of the capacitor 106 and the source terminal of the second thin film transistor 105. . The drain terminal of the second thin film transistor 105 is connected to the data line 114, and the gate terminal is connected to the gate line 112. The other end of the capacitor 106 is also connected to the common line 113.

The gate line 112, the batch write line 111, and the common line 113 are connected to the gate driver 131, and the data line 114 is connected to the data driver 132. The common line 113 is grounded in the gate driver 131. This ground voltage is the reference voltage of the image signal applied to the data line 114 and is equal to the voltage applied to the common electrode 117 formed on the rear surface of the upper substrate 102.

The upper substrate 102 is formed with a transparent common electrode 117 facing each pixel electrode 103 of the lower substrate 101 and supplied with a ground voltage. Further, alignment films 118 and 119 are formed on the electrode formation surfaces of the lower substrate 101 and the upper substrate 102, respectively, and the alignment films 118 and 119 are organic polymer compounds such as polyimide. The opposing surfaces of the alignment films 118 and 119 are subjected to alignment treatment such as rubbing.

As such, the upper substrate 102 and the lower substrate 101 are bonded to each other with the actual material 120 therebetween. The liquid crystal 121 is injected and sealed in an area surrounded by the real material 120 between the upper substrate 102 and the lower substrate 101. The thickness of the liquid crystal 121 is maintained at predetermined intervals by the real material 120 and the transparent gap material 122.

In the liquid crystal 121, when an absolute value of a voltage higher than a predetermined value is applied between the pixel electrode 103 and the common electrode 117, the liquid crystal 121 is formed of liquid crystal molecules depending on the polarity of the applied voltage. It is set to either of the first alignment state oriented in the direction and the second alignment state in which the liquid crystal molecules are aligned in a direction different from the first alignment state. In addition, when a voltage whose absolute value is lower than a predetermined value is applied, liquid crystal molecules are in an average arrangement state or an intermediate state of the first and second alignment states as the helix of the liquid crystal 121 is distorted. The alignment state of the liquid crystal 121 is set according to the transmission axes of the pair of polarizing plates 123 and 124 disposed above and below the liquid crystal cell 126.

The light sources 13R, 13G, and 13B irradiate the display surface of the liquid crystal display element 11 with light of red (R), green (G), and blue (B), respectively. These light sources 13R, 13G, 13B are sequentially flashed by the drive signals supplied from the light source driver 17, respectively.

The liquid crystal drive unit 15 receives a video signal from an interface unit (not shown), which is a video signal for red (R) (gradation signal for R image) and a video signal for green (G) (gradation signal for G image). ), And the picture signal for blue (B) (gradation signal for B picture) and the synchronization signal. The liquid crystal drive unit 15 sequentially converts a black (black) gray image for red (R), a black and white gray image for green (G), and a black and white gray image for blue (B) based on the separated signal. The timing signal instructing the timing of turning on the light sources 13R, 13G, and 13B while being displayed on (11) is supplied to the light source driver 17.

The light source driver 17 corresponds to a timing signal supplied from the liquid crystal driver 15 so that the image displayed by the liquid crystal display 11 and the color of light irradiated by the light sources 13R, 13G, and 13B correspond to each other. 13G, 13B). That is, the light source driver 17 turns on the light source 13R when the liquid crystal display element 11 is displaying a black and white gradation image for red (R), and the liquid crystal display element 11 is monochrome for green (G). When the gradation image is displayed, the light source 13G is turned on. In addition, when the liquid crystal display element 11 displays a monochrome grayscale image for blue (B), the light source 13B is turned on.

The operation of the sequential blinking liquid crystal display will be described with reference to the timing chart of FIG. 4.

Referring to FIG. 4, the sequentially flickering liquid crystal display divides one full color image into three images of red (R), green (G), and blue (B), and displays them in order. The resultant image is synthesized by the visual afterimage phenomenon of the observer to display the full color image.

At this time, the liquid crystal driver 15 divides the supplied video signal into R, G, and B video signals, and supplies the R, G, and B video signals to the data driver 132 according to the synchronization signal. In addition, the synchronization signal is supplied to the gate driver 131.

In the liquid crystal display element 11 as described above, writing of the display image is performed in units of rows. For example, assuming that the liquid crystal display element 11 displays red (R) bright and the light source 13R is lit, as in the waveforms (A) and (B), during this period, Likewise, the gate driver 131 applies a gate pulse to the gate line 112. The second thin film transistor 105 whose gate is connected to the gate line 112 of the first row is turned on by this gate pulse. At this time, the data driver 132 applies a voltage signal indicating the display gray level of each pixel of the first row of the black and white grayscale image for green (G) to the data line 114 as shown in (I). The voltage signal supplied to the data line 114 is applied to the capacitor 106 between the second thin film transistor 105 of the first row, which is turned on, and charged.

If a predetermined write time elapses after the second thin film transistor 105 is turned on, the gate driver 131 turns off the gate pulse as shown in (F). Accordingly, the second thin film transistor 105 is also turned off, and the capacitor 106 maintains the charging voltage. That is, the capacitor 106 writes the video signal of the green (G) black and white gradation image which indicates the display gradation of each pixel of the first row.

Then, as in FIG. 4G, the gate driver 131 applies a gate pulse to the gate line 112 of the second row. At this time, the data driver 132 applies the voltage signal of the image for green (G) indicating the display gray level of each pixel in the second row to the data line 114. Accordingly, the voltage signal of the image for green (G) indicating the display gray level of each pixel of the second row is written into the capacitor 106 of the second row.

Thereafter, the above-described operation with respect to the third row, the fourth row, ... is repeated. As shown in (H) and (I), the video signal for green (G) is written in the capacitor 106 of the previous row up to the last row. Then, when the display period of the red (R) image ends, the display period of the green (G) image starts as shown in (E). At this time, the gate driver 131 applies a gate pulse to the batch write line 111. Accordingly, as all of the first thin film transistors 104 are turned on, the voltage (voltage indicating the gray level of each pixel of the green (G) grayscale image) held by each capacitor 106 is changed to the pixel electrode ( 103). When the voltage of the pixel electrode 103 is stabilized as in (E), the gate driver 131 turns off the gate pulse of the batch write line 111. Accordingly, the first thin film transistor 104 is turned off, and the voltage applied to the pixel electrode 103 until the first thin film transistor 104 is turned on by the opposing portion of the pixel electrode 103 and the common electrode 117 and the liquid crystal therebetween. It is maintained at the pixel capacity to be formed. The alignment state of the liquid crystal 121 is changed by the voltage held in the pixel capacitor, and the monochrome grayscale image corresponding to the image signal is displayed on the liquid crystal display element 11.

As shown in FIG. 4E, the start pulse is also supplied to the light source driver 17. The light source driver 17 is applied at the same time as the start pulse or after a predetermined time after the start pulse is applied, as shown in (C), the green (G) light source 13G is turned on so that the liquid crystal display element 11 is turned on. Green (G) light is irradiated. As a result, a green (G) image is applied to the liquid crystal display element 11 as in (A).

In the period in which the green (G) image is being displayed, as in (F) to (H), the gate driver 131 sequentially applies gate pulses to the first row of the gate line 112. The data driver 132 applies a voltage signal indicating the display gray level of each pixel of the blue (B) image to the data line 114 as in (I). As a result, after the video signal of the blue (B) image is written into each capacitor 106 in units of rows, the display period of the blue (B) image is started. At this time, the gate driver 131 applies the start pulse to the batch write line 111 as in (E). By this start pulse, all the first thin film transistors 104 are turned on at the same time, and the voltage held in each capacitor 106 is transferred to the pixel capacitance. As the alignment state of the liquid crystal 121 is changed by the voltage held in each pixel capacitor, the gray scale for the image of blue (B) is displayed. In addition, the light source driver 17 turns on the light source 13B for blue B as shown in FIG. 4D. Such display of R, G, and B gradation images is repeatedly performed.

As described above, in the liquid crystal display device which is sequentially blinking, the image of the green (G) image is sequentially sequentially by the sample and hold circuit while the light source means irradiates the liquid crystal display element 11 with red (R) light. The signal is written, and after the writing is completed, the sample hold circuit cuts off the video signal supplied to each pixel electrode. At this time, the light source irradiates the liquid crystal display element 11 with green G light to display the green G image on the pixel electrode without writing time. Therefore, the liquid crystal display element 11 can lengthen the time for irradiating light corresponding to one field by the light source means, and can display a bright image. In addition, since it is not necessary to arrange a mechanism such as a color filter, the size can be reduced.

However, the liquid crystal display device disclosed in Japanese Patent Application Laid-Open No. 08-095526 described above causes the backlight to flash sequentially in synchronization with the color of data. However, there is no method for sequentially blinking the backlight and no specific hardware for implementing the backlight. Therefore, the liquid crystal display device disclosed in Japanese Patent Application Laid-Open No. 08-095526 is difficult to be practically implemented.

Accordingly, it is an object of the present invention to provide a backlight driving apparatus and method for a liquid crystal display device which can sequentially flash by color using a synchronization signal three times the synchronization signal used in a liquid crystal panel.

1 is a block diagram showing a conventional backlight driving device.

2 is a cross-sectional view showing in detail the liquid crystal panel shown in FIG.

3 is a block diagram showing a conventional liquid crystal display device.

4 is a timing diagram showing waveforms for driving the backlight shown in FIG.

5 is a block diagram showing a backlight driving apparatus of a liquid crystal display device according to the present invention;

FIG. 6 is a timing diagram showing waveforms for driving the backlight unit shown in FIG. 5; FIG.

<Explanation of symbols for main parts of drawing>

11, 20: liquid crystal display element 13R, 13G, 13B, 40R, 40G, 40B: light source

15: liquid crystal driver 17: light source driver

20: liquid crystal panel 22, 132: data driver

24, 131: gate driver 26: timing controller

30: backlight driver 32: frequency multiplier

34: backlight timing unit 36: LED driver

38: RGB selector 39: switch

40: backlight 101: substrate

103: pixel electrode 104, 105: TFT

106: capacitor 111: batch write line

112: gate line 113: common line

114: data line 117: common electrode

118, 119: alignment film 120: real

121: liquid crystal 122: gap material

123, 124: polarizer

In order to achieve the above object, the backlight driving apparatus of the liquid crystal display device according to the present invention is a red light source for irradiating red light to the liquid crystal panel, a green light source for irradiating green light to the liquid crystal panel, and the blue light to the liquid crystal panel Indicating a flashing timing of the red light source, the green light source and the blue light source by the multiplier for multiplying the blue light source, the frequency of the reference vertical synchronization signal and the horizontal synchronization signal by a predetermined multiple, and the vertical synchronization signal and the horizontal synchronization signal. A timing control unit for generating a timing signal, a light source selection unit for generating a light source selection signal for selecting one of a flashing timing signal of a red light source, a green light source and a blue light source, a red light source, a green light source and a blue light source A light source driver for generating a drive signal for driving and a light source driver by controlling the light source selection signal Of the drive signal and a switching element for supplying to any one of the red light source, green light source and blue light source.

In the backlight driving apparatus of the liquid crystal display according to the present invention, the frequency multiplier multiplies the frequency of the reference vertical synchronization signal and the horizontal synchronization signal by three times. In addition, the light source selection signal is characterized by having a logic value of at least 2 bits.

In the backlight driving apparatus of the liquid crystal display device of the present invention, the timing controller includes three vertical synchronization signals multiplied sequentially to delay the vertical synchronization signals multiplied to indicate the lighting periods of the red light source, the green light source, and the blue light source, respectively, within the reference vertical sync signal period. It is characterized by generating a timing signal.

In the backlight driving method of the liquid crystal display according to the present invention, multiplying the frequencies of the reference vertical synchronization signal and the horizontal synchronization signal by a predetermined multiple, and blinking the red light source, the green light source, and the blue light source by the multiplied vertical and horizontal synchronization signals. Generating a timing signal indicative of timing; generating a light source selection signal for selecting any one of a flashing timing signal of a red light source, a green light source, and a blue light source; driving a red light source, a green light source, and a blue light source; And generating a driving signal to supply the light source driving signal to any one of a red light source, a green light source, and a blue light source by controlling the light source selection signal.

Other objects and features of the present invention in addition to the above objects will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 5 and 6.

Referring to FIG. 5, the backlight driving apparatus of the liquid crystal display device according to the present invention supplies a liquid crystal panel 20, a data driver 22 to supply a data signal to the liquid crystal panel 20, and a scan signal to the liquid crystal panel. The gate driver 24, the data driver 22, the data signal and the control signal, the timing controller 26 supplies the scanning control signal to the gate driver 24, and the light is supplied to the liquid crystal panel 20. The backlight unit 40 to irradiate, and the backlight drive unit 30 for sequentially driving the backlight 40 is provided.

The liquid crystal panel 20 is formed at the intersections of the liquid crystal cells arranged in a matrix form and the m gate lines GL and the n data lines DL to switch the data signals supplied to the liquid crystal cells. A thin film transistor ("TFT") is provided as a switching device.

The data driver 22 supplies the data signal RGB data to the liquid crystal panel 20 in response to the control signals input from the timing controller 26.

The gate driver 24 controls the gate terminals of the TFTs arranged on the liquid crystal panel 20 on / off line by line in response to control signals input from the timing controller 26. The data signal supplied from 22 is applied to each pixel connected to each TFT.

The timing controller 26 receives data signals RGB data and control signals (for example, an input clock, a horizontal synchronization signal, a vertical synchronization signal, and a data enable signal) input from an interface unit (not shown). The timing controller 26 supplies the data signal RGB data and the data enable signal to the data driver 22. In addition, the timing controller 26 generates a gate start clock GSC and a gate scanning pulse GSP from the horizontal synchronizing signal H and the vertical synchronizing signal V, and supplies them to the gate driver 24.

In this way, the scanning signal is supplied from the gate driver 24, the thin film transistor TFT is turned on, and the data signal RGB data supplied from the data driver 22 is supplied to the liquid crystal cell. Accordingly, in the liquid crystal cell, the arrangement state of the liquid crystal molecules is set according to the voltage of the data signal RGB data supplied. The transmitted light is adjusted according to the arrangement state of the liquid crystal molecules. This light is irradiated in synchronization with the data signal by the backlight unit 40.

In detail, the backlight unit 40 includes red, green, and blue light sources 40R, 40G, and 40B. The brightness of the backlight unit 40 is determined by a current supplied to a light emitting diode. The red, green, and blue light sources 40R, 40G, and 40B are sequentially flashed by the control signal supplied from the backlight driver 30.

To this end, the backlight driver 30 is supplied from the frequency multiplier 32 and the frequency multiplier 32 that receives the vertical and horizontal synchronization signals (V, H) and converts the multiplication frequency (3Hsync, 3Vsync) of three times A backlight timing unit 34 for generating a backlight timing signal BLC according to a multiplication frequency 3Hsync, 3Vsync and the vertical synchronization signal V, and an RGB selector for selecting an RGB signal according to the backlight timing signal BLC A switch 39 for selectively selecting any one of red, green, and blue light sources 40R, 40G, and 40B by an RGB select signal RGB_SW supplied from the RGB selector 38; An LED driver 36 is provided between the switch 39 and the frequency multiplier 32 to supply a constant current to the switch 39.

The frequency multiplier 32 converts the vertical and horizontal synchronization signals V and H supplied from an interface (not shown) to have three vertical and horizontal frequencies 3 Vsync and 3 Hsync, respectively. Here, the vertical and horizontal synchronization signals V and H supplied from the interface unit are the same as those of the Video Electronics Standard Association (VESA).

The backlight timing unit 34 receives the vertical and horizontal frequencies 3Vsync and 3Hsync supplied from the frequency multiplier 32 and the vertical synchronization signal 1Vsync from the interface, and sequentially flashes the backlight unit 40 in synchronization with the data signal. To generate a backlight timing signal BLC.

The RGB selector 38 receives one of the RGB select signals RGB_SW among red (R), green (G), and blue (B) in synchronization with the backlight timing signal BLC supplied from the backlight timing unit 34. Will be chosen. The selected RGB signal is supplied to the switch 39.

The switch 39 sequentially flashes the red, green, and blue light sources 40R, 40G, and 40B by the RGB select signal RGB_SW supplied from the RGB selector 38. In addition, the switch 39 receives the constant current Vi from the LED driver 36, and supplies the constant current Vi to the red, green, and blue light sources 40R, 40G, and 40B.

The LED driver 36 includes a constant current circuit having a large capacitance and a constant current value because the backlight unit 40 operates with a current. The constant current Vi generated from the LED driver 36 is supplied to each light source of the backlight unit 40 through the switch 39.

Such a liquid crystal display according to the present invention will be described with reference to the timing diagram of FIG. 6.

FIG. 6 illustrates that red (R), green (G), and blue (B) are driven once each time, that is, the backlight unit 40 is not dividedly driven per horizontal period of the horizontal synchronization signal 1Hsync of the liquid crystal panel 20. Indicates.

In FIG. 6, the backlight unit 40 has vertical and horizontal synchronization signals 3Vsync and 3Hsync and one cycle in which vertical and horizontal synchronization signals 1Vsync and 1Hsync supplied to the liquid crystal panel 20 are converted to three times the frequency. The vertical synchronization signal 1Vsync is supplied to the backlight timing unit 34 to generate the backlight timing signal BLC. The backlight timing unit 34 is synchronized with the rising intervals of the vertical synchronization signal 3Vsync during the vertical synchronization signal 1Vsync of one cycle, and the respective red backlight timing signals RB / L and green backlight timing signals GB / L. ) And a blue backlight timing signal BB / L are sequentially generated. At this time, the horizontal synchronization signal 3Hsync serves as a clock signal.

These red, green, and blue backlight timing signals R-B / L, G-B / L, and B-B / L are sequentially supplied to the RGB selector 38. The RGB selector 38 receives the vertical and horizontal synchronization signals 3Vsync and 3Hsync and one cycle of the vertical synchronization signal 1Vsync from the backlight timing unit 34 to output the red, green and blue backlight timing signals RB / L, One of the timing signals RB / L, GB / L, and BB / L from among GB / L and BB / L is selected. The red, green, and blue backlight timing signals R-B / L, G-B / L, and B-B / L are detected and selected by comparing the clock synchronization signal 3Hsync and the vertical synchronization signal 3Vsync. The RGB selection signal RGB_SW thus selected is supplied to the switch 39.

The switch 39 receives the constant current Vi from the LED driver 36 and is supplied to any one of the red, green, and blue light sources 40R, 40G, and 40B selected by the RGB selection signal RGB_SW. In the switch 39, the red, green, and blue light sources 40R, 40G, and 40B are selected by a multiplexer (not shown). For example, when the logic value of the RGB select signal RGB_SW supplied from the RGB selector 38 is "100", the red light source 40R is turned on and the remaining green and blue light sources 40G and 40B are turned off. . Since the multiplexer of the RGB selector 38 has three cases for selecting a light source, it is preferable to have a logic value of at least 2 bits.

Accordingly, the red, green, and blue light sources 40R, 40G, and 40B are made using the vertical synchronization signal 3Vsync multiplied while the reference vertical synchronization signal 1Vsync supplied to each gate line of the liquid crystal panel 20 is supplied. By blinking light is sequentially irradiated to the liquid crystal panel 20.

As described above, the backlight driving apparatus and method of the liquid crystal display according to the present invention converts the multiplied synchronization signal generated by multiplying the synchronization signal used for the liquid crystal panel of the liquid crystal display at a frequency of three times as the driving signal of the backlight. By using it, driving of a backlight can be made easy. In addition, since the backlight driver uses a synchronization signal supplied to the liquid crystal panel, the backlight driving device can be easily applied even when the frame frequency is changed.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (10)

Red light source for irradiating red light to the liquid crystal panel, A green light source for irradiating green light to the liquid crystal panel; A blue light source for irradiating blue light to the liquid crystal panel; A frequency multiplier for multiplying the reference vertical synchronization signal and the horizontal synchronization signal by a predetermined multiple, respectively; A timing controller for generating a timing signal indicating a timing of blinking of the red light source, the green light source, and the blue light source by the multiplied vertical synchronization signal and horizontal synchronization signal; A light source selection unit generating a light source selection signal for selecting any one of the flashing timing signals of the red light source, the green light source, and the blue light source; A light source driver for generating a driving signal for driving the red light source, the green light source, and the blue light source; And a switch element for supplying a drive signal from the light source driver to any one of the red light source, the green light source, and the blue light source under the control of the light source selection signal. The method of claim 1, The frequency multiplier multiplies the frequencies of the reference vertical synchronization signal and the horizontal synchronization signal by three times. The method of claim 1, And the light source selection signal has a logic value of at least 2 bits. The method of claim 1, The timing controller generates three timing signals for sequentially delaying the multiplied vertical synchronization signal within the reference vertical synchronization signal period to indicate the lighting periods of the red light source, the green light source, and the blue light source, respectively. Backlight drive device for a liquid crystal display device. The method of claim 4, wherein And the light source selecting unit supplies a light source selection signal having a logic value indicating one of the three timing signals in synchronization with the multiplied vertical synchronization signal and a reference vertical synchronization signal to the switch element. Backlight drive. Multiplying the frequencies of the reference vertical synchronization signal and the horizontal synchronization signal by a predetermined multiple, respectively; Generating a timing signal indicating a timing of blinking a red light source, a green light source, and a blue light source by the multiplied vertical and horizontal synchronization signals; Generating a light source selection signal for selecting any one of the flashing timing signals of the red light source, the green light source, and the blue light source; Generating driving signals for driving the red light source, the green light source, and the blue light source; And supplying the light source driving signal to any one of the red light source, the green light source, and the blue light source by controlling the light source selection signal. The method of claim 6, The frequency multiplication multiplies the frequency of the reference vertical synchronization signal and the horizontal synchronization signal by three times. The method of claim 6, And the light source selection signal has a logic value of at least 2 bits. The method of claim 6, The timing signal may be three timing signals in which the multiplied vertical synchronization signal is sequentially delayed in the reference vertical synchronization signal period so as to indicate the lighting periods of the red light source, the green light source, and the blue light source, respectively. Backlight driving method of liquid crystal display device. The method of claim 9, And the light source selection signal has a logic value indicating one of the three timing signals in synchronization with the multiplied vertical synchronization signal and a reference vertical synchronization signal.