KR20120020454A - Apparatus and method for liquid crystal display device - Google Patents

Abstract

PURPOSE: A liquid crystal display apparatus and a driving method thereof are provided to prevent a variation in brightness between the lower end part and the upper end part of a liquid crystal panel, thereby improving display quality. CONSTITUTION: First and second common voltages are respectively supplied to first and second active regions. The first common voltage and the second common voltage have different polarity. Data voltage is supplied to each data line according to a scan signal. A first light source group and a second light source group are switched on according to duty ratio. The first light source group is switched off at a time point in which the polarity of the first common voltage is converted. The second light source group is switched off at a time point in which the polarity of the second common voltage is converted.

Description

Liquid crystal display and driving method {APPARATUS AND METHOD FOR 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 liquid crystal display device and a driving method thereof, which can improve display quality and reduce manufacturing cost by driving a common voltage swing.

With the development of various portable electronic devices such as mobile communication terminals and notebook computers, there is an increasing demand for a flat panel display device applicable thereto.

As a flat panel display, a liquid crystal display device, a plasma display panel, a field emission display device, and a light emitting diode display device are studied. have. Among flat panel display devices, liquid crystal display devices have been expanded in application fields due to development of mass production technology, ease of driving means, low power consumption, high image quality, and large screen.

The liquid crystal display displays an image by adjusting light transmittance for each pixel according to an input signal. To this end, the liquid crystal display includes a liquid crystal panel in which a plurality of pixels (liquid crystal cells) are arranged in a matrix, a backlight unit for supplying light to the liquid crystal panel, and a driving circuit unit for driving the liquid crystal panel and the backlight. It is done by

The driving circuit unit may include a data driver for supplying image data (data voltage) to the liquid crystal panel; A gate driver supplying a scan signal to the liquid crystal panel; A timing controller for generating digital image data (R, G, B) by arranging image signals from the outside in units of frames and generating driving control signals (DCS, GCS) of the data driver and the gate driver; And a backlight driver configured to drive a backlight for supplying light to the liquid crystal panel.

The gate driver sequentially supplies a scan signal (gate driving signal) for turning on a thin film transistor (TFT) formed in each pixel to each of the plurality of gate lines. As a result, the pixels of the liquid crystal panel are sequentially driven, and the data driver supplies a data signal to each of the plurality of data lines according to the scan signal.

1 and 2 illustrate a method of driving a liquid crystal display according to the related art.

FIG. 1 illustrates one scan signal among sequentially scanned signals supplied to a plurality of gate lines formed in the liquid crystal panel, and is applied to the data voltage and the common voltage Vcom supplied according to the one scan signal. The pixel voltage (pixel voltage) formed by this is shown.

1 and 2, the liquid crystal display according to the related art maintains the common voltage Vcom constant and supplies a data voltage to each pixel according to a scan signal supplied to each pixel.

The pixel voltage is formed by the voltage difference between the common voltage and the data voltage supplied to each pixel, and grayscale is realized by adjusting the light transmittance through the arrangement of liquid crystals according to the pixel voltage.

Here, the data voltage may be supplied to each pixel symmetrically, that is, in a frame inversion manner so as to have polarities opposite to each other in a frame unit.

Through the frame inversion scheme, the polarities of the data voltages supplied to the pixels are temporally and spatially driven so that the data voltages are not biased in one polarity on a plurality of frames.

The data voltage is supplied at a time when the TFT of each pixel is turned on by the scan signal, that is, at a gate on time, and a difference between the data voltage and the common voltage supplied at the gate on time. The pixel voltage is charged in the storage capacitor Cst so that the pixel voltage is maintained during the gate off time.

In the prior art, the liquid crystal display maintains a common voltage to drive the frame inversion method and supplies the data voltage to have a polarity of the positive electrode (+) and the negative electrode (−) at a frame period.

Therefore, the data driver must supply the data voltage (+ V) of the positive electrode and the data voltage (-V) of the negative electrode, and thus have a voltage driving range of 2V. Therefore, there is a problem in that the manufacturing cost of the liquid crystal display is increased due to the application of the data driver having a high voltage driving range.

In order to improve the problem that the voltage driving range of the data driver is increased due to the application of the frame inversion method, a method of supplying different polarities of the common voltages at a frame period, that is, a Vcom swing method, has been proposed.

In the liquid crystal display according to the related art, a pixel voltage is formed in each pixel by supplying a data voltage to each pixel and swinging a common voltage to the positive electrode and the negative electrode at a frame period.

Here, the common voltage is simultaneously supplied to all pixels, but the data voltages supplied to each pixel are sequentially supplied according to scan signals sequentially applied to the plurality of gate lines.

At this time, the pixel voltage must be maintained until a new data voltage is supplied. That is, the pixel voltage between the common voltage and the data voltage must be kept constant so that the voltage formed on the liquid crystal of each pixel is not maintained while the thin film transistor TFT is turned off.

However, before the new data voltage is supplied, the polarity of the common voltage is inverted from the positive (+) to the negative (-) or from the negative (-) to the positive (+), which causes the pixel voltage to change along with the common voltage. As a result, the original voltage value cannot be maintained. That is, when the common voltage Vcom is converted from high to low or from low to high, the pixel voltage is converted so that the pixel voltage charged in the storage capacitor does not maintain a constant voltage value. The voltage falls or rises along the common voltage.

As the gate voltage of the thin film transistor TFT and the state of the pixel voltage Vgate-pixel leave the off current state, a back current flows in the thin film transistor TFT. As a result, the Vcom-pixel voltage of the storage capacitor, that is, the voltage applied to the liquid crystal is lowered. As shown in FIG. 3, there is a problem in that a luminance difference occurs at the upper end and the lower end of the liquid crystal panel 10.

Uniformity of the luminance of the liquid crystal panel 10 is lowered due to the difference in the luminance of the upper and lower portions of the liquid crystal panel 10, and the luminance deviation is intensified from the upper end to the lower end of the liquid crystal panel 10. There is a problem of degrading the quality.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and in the case of applying the frame inversion method through a common voltage swing, a liquid crystal display device which can improve display quality by preventing occurrence of luminance deviation between an upper end portion and a lower end portion of a liquid crystal panel; It is an object to provide a driving method.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a liquid crystal display and a driving method which can reduce manufacturing cost by lowering the driving voltage range of the data driver.

The driving method of the liquid crystal display according to the exemplary embodiment of the present invention divides the entire active area of the liquid crystal panel into a first active area and a second active area, and divides the entire active area into the first active area and the second active area during one frame period. Supplying a first common voltage and a second common voltage having different polarities, respectively; Supplying a data voltage for each data line according to a scan signal based on a time point at which polarities of the first common voltage and the second common voltage are switched; Turning on a first light source group disposed to correspond to the first active region and a second light source group disposed to correspond to the second active region by a duty ratio set during the one frame period; And turning off the first light source group when the polarity of the first common voltage is switched, and turning off the second light source group when the polarity of the second common voltage is switched. It is characterized by.

According to an exemplary embodiment of the present invention, a liquid crystal display includes: a liquid crystal panel in which an entire active area is divided into a plurality of active areas; A timing controller generates a backlight control signal for controlling the on-off time and duty ratio of the light sources and a common voltage control signal for controlling the common voltage supplied to each of the plurality of active regions. ; A common voltage supply unit generating a common voltage based on the common voltage control signal and supplying common voltages having different polarities to adjacent active regions during one frame period; A data driver for supplying data voltages to the pixels of the plurality of active regions on the basis of the point in time at which the polarities of the common voltages of the different polarities are converted; And a backlight driver configured to drive the light sources based on a time point at which polarities of the common voltages having different polarities are converted based on the backlight control signal.

According to an exemplary embodiment of the present invention, when the frame inversion method is applied through a common voltage swing, display quality of the liquid crystal display may be improved by preventing occurrence of luminance deviation between the upper end and the lower end of the liquid crystal panel.

According to an exemplary embodiment of the present invention, the driving voltage range of the data driver may be lowered to reduce the manufacturing cost of the liquid crystal display.

According to an exemplary embodiment of the present invention, display quality may be improved by improving motion blur.

1 and 2 illustrate a method of driving a liquid crystal display according to the prior art.
3 is a diagram illustrating a problem that a luminance difference occurs between an upper portion and a lower portion due to a common voltage swing driving of a liquid crystal display according to the related art.
4 is a diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention.
5 to 7 illustrate a method of driving a liquid crystal display according to an exemplary embodiment of the present invention.
8 is a view illustrating a light source arrangement of a liquid crystal display according to another exemplary embodiment of the present invention.
9 is a view showing a liquid crystal display and a driving method according to another embodiment of the present invention.

Hereinafter, a driving apparatus and a driving method of a liquid crystal display according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

4 is a diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention, and FIGS. 5 to 7 are diagrams illustrating a driving method of a liquid crystal display according to an exemplary embodiment of the present invention.

4 to 7, the liquid crystal display 100 according to an exemplary embodiment of the present invention may include a liquid crystal panel 110 for displaying an image according to image data, and a backlight for supplying light to the liquid crystal panel 110. And a driving circuit unit for driving the light source of the liquid crystal panel 110 and the backlight unit 150.

The liquid crystal panel 110 includes an upper substrate and a lower substrate bonded together with a liquid crystal layer (not shown) therebetween, and pixels for displaying an image are arranged in a matrix form.

The upper substrate may include a black matrix defining a pixel area to correspond to each of the plurality of pixels; Red, green, and blue color filters formed in each pixel area defined by the black matrix; And an overcoat layer formed to cover the red, green, and blue color filters and the black matrix to planarize the upper substrate.

As shown in FIG. 4, the lower substrate includes a plurality of gate lines 112 and a plurality of data lines 114, and a plurality of pixels are formed by the intersection of the gate lines 112 and the data lines 114. Is defined.

Each of the plurality of pixels includes a thin film transistor 118 (TFT) and a storage capacitor Cst formed at an intersection of the gate line 112 and the data line 114.

Here, when the gate terminal of the thin film transistor is connected to the gate line, and the source terminal is connected to the data line, the drain terminal is connected to the pixel electrode.

The liquid crystal panel 110 is provided with a first common electrode supplied with the first common voltage Vcom1 from the first common voltage supply unit 170, and a second common voltage Vcom2 supplied from the second common voltage supply unit 180. And a second common electrode.

Here, the first common electrode is formed in the first active region corresponding to the upper end with respect to the center of the liquid crystal panel 110 among the entire active regions of the liquid crystal panel 110. The second common electrode is formed in the second active region corresponding to the lower end with respect to the center of the liquid crystal panel 110.

In this case, the first common voltage Vcom1 supplied to the first common electrode and the second common voltage Vcom2 supplied to the second common electrode are swinged in a frame period to switch polarity. Through this, the liquid crystal panel 110 is driven in a frame inversion method to display an image.

In addition, the first common voltage Vcom1 and the second common voltage Vcom2 have polarities opposite to each other in the same frame, and a plurality of common voltages having polarities opposite to each other are respectively provided on the upper and lower ends of the liquid crystal panel 110. Supply can prevent the occurrence of vertical luminance deviation due to the common voltage swing.

The backlight unit 140 supplies light to the liquid crystal panel 110, and includes a plurality of light sources for generating light and a diffusion plate (edge) for guiding light generated from the light source toward the liquid crystal panel 110. A light guide plate) and at least one optical sheet (diffuser sheet, prism sheet, dual brightness enhancement film) which improves the efficiency of light irradiated to the liquid crystal panel 110. can do.

As illustrated in FIG. 5, the plurality of light sources may include a plurality of Cold Cathode Fluorescent Lamps (CCFLs) or a plurality of Light Emitting Diodes (LEDs). 5 illustrates a direct type in which a light source is disposed below the liquid crystal panel 110.

In this case, the plurality of light sources may be configured as a plurality of light source groups so as to correspond to the first active region corresponding to the upper end and the second active region corresponding to the lower end with respect to the center of the liquid crystal panel 110. have.

The first light source group 142 of the plurality of light source groups is disposed to correspond to the first active region to which the first common voltage Vcom1 is supplied, and is driven under the control of the backlight driver 150.

In detail, an on-off time of the first light source group 142 is controlled based on a time point when the polarity of the first common voltage Vcom1 is changed, and according to a set duty ratio. It remains on.

As an example, the first light source group 142 maintains an on state for a duty ratio set within one frame period, and then the polarity of the first common voltage Vcom1 is negative at the positive electrode. It is turned off at the time of conversion from the negative pole or the negative pole to the positive pole. After the off state, the on-state is maintained as much as the duty ratio reversed from the time when the polarity of the first common voltage Vcom1 is changed next time.

Among the plurality of light source groups, the second light source group 144 is disposed to correspond to the second active region to which the second common voltage Vcom2 is supplied, and is driven under the control of the backlight driver 150.

The second light source group 144 has an on-off time controlled based on a time point when the polarity of the second common voltage Vcom2 is changed, and is turned on according to a set duty ratio. State is maintained.

As an example, the second light source group 144 maintains an on state by a duty ratio set within one frame period, and then the polarity of the second common voltage Vcom2 is negative at the positive electrode. It is turned off at the time of conversion from the negative pole or the negative pole to the positive pole. After the off state, the on-state is maintained by the duty ratio reversed from the time when the polarity of the second common voltage Vcom2 is changed next time.

As described above, an on-off time point of the first light source group 142 is controlled according to the first common voltage Vcom1, and the second light source group 144 is connected to the second common voltage Vcom2. Accordingly, since the on-off time point is controlled, the first light source group 142 and the second light source group 144 may be on-off at different time points.

The driving circuit unit gate driver 120; Data driver 130; Timing controller 140; A backlight driver 150 driving a light source of the backlight unit 150; A first common voltage supplier 170 supplying a first common voltage Vcom1 to the liquid crystal panel 110; And a second common voltage supplier 180 supplying a second common voltage Vcom2 to the liquid crystal panel 110.

The timing controller 140 generates a gate control signal GCS for controlling the gate driver 120 by using the vertical / horizontal synchronization signal and a clock signal, and generates the gate control signal GCS. To feed.

The gate control signal GCS may include a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable (GOE), and the like.

In addition, the timing controller 140 generates a data control signal DCS for controlling the data driver 130 and supplies the data control signal DCS to the data driver 130.

The data control signal DCS may include a source start pulse (SSP), a source sampling clock (SSC), a source output enable (SOE), and a polarity control signal (POL). Polarity) and the like.

In addition, the timing controller 140 generates a backlight control signal (BCS) for driving the plurality of light sources using the vertical / horizontal synchronization signal and the clock signal, and generates the backlight control signal by the backlight driver 150. Supplies).

Here, the backlight control signal includes a signal for controlling on-off time, luminance, and duty of each of the plurality of light sources.

In addition, the timing controller 140 uses a vertical / horizontal synchronization signal and a clock signal to generate a common voltage control signal for generating the first common voltage Vcom1 and the second common voltage Vcom2 supplied to the liquid crystal panel 110. The Vcom control signal is generated, and the generated common voltage control signal is supplied to the first common voltage supply unit 170 and the second common voltage supply unit 180.

In addition, the timing controller 140 aligns the image signals from the outside and converts them into digital image data (R, G, B) in units of frames, and provides the image driver 130 in which image data is aligned in units of frames.

The gate driver 120 generates a scan signal for driving the thin film transistors 118 formed in each pixel of the liquid crystal panel 110 based on the gate control signal GCS from the timing controller 140, and generates the generated scan signal. The signal is sequentially supplied to the plurality of gate lines 112.

The data driver 130 converts the digital image data R, G, and B provided from the timing controller 140 into analog data voltages. The converted data voltage is supplied to the plurality of data lines 114 at a time when the thin film transistor TFT of each pixel is turned on based on the data control signal DCS from the timing controller 140. .

The backlight driver 150 drives the light sources of the first light source group 142 and the second light source group 144 according to the backlight control signal BCS input from the timing controller 160.

In this case, the backlight driver 150 turns on the first light source group 142 and the second light source group 144 by a duty ratio set within one frame period according to the backlight control signal BCS. on) to maintain the state.

In addition, the backlight driver 150 has a polarity of the first common voltage Vcom1 and the second common voltage Vcom2 from a positive pole to a negative pole or from a negative pole to a positive pole. The first light source group 142 and the second light source group 144 are driven to be turned off at the time of conversion to the pole.

The backlight driver 150 may drive the first light source group 142 and the second light source group 144 to be turned on and off at different points in time, and the image displayed on the liquid crystal panel 110 may be clearly expressed. The duty ratio and brightness of the light source can be controlled.

The liquid crystal display 100 according to the exemplary embodiment divides the entire active area of the liquid crystal panel 110 into a plurality of active areas, and supplies different common voltages Vcom to the divided plurality of active areas, respectively. do.

As an example, the first common voltage Vcom1 and the second common voltage Vcom2 having different polarities are provided to the plurality of active regions in one frame.

To this end, it includes a common voltage supply unit for generating and supplying a plurality of different common voltage, as an example, as shown in Figure 4, includes a first common voltage supply unit 170 and a second common voltage supply unit 180 can do.

The first common voltage supply unit 170 generates a first common voltage Vcom1 according to a common voltage control signal Vcom control signal supplied from the timing controller 160, and generates the generated first common voltage Vcom1. Supply to a first active region of the plurality of active regions. The first active region may correspond to an upper end of the liquid crystal panel 110 with respect to the center of the liquid crystal panel 110.

The second common voltage supply unit 180 generates a second common voltage Vcom2 according to a common voltage control signal Vcom control signal supplied from the timing controller 160, and generates the generated second common voltage Vcom2. Supply to a second active region of the plurality of active regions. The second active region may correspond to the lower end of the liquid crystal panel 110 with respect to the center of the liquid crystal panel 110.

The first common voltage Vcom1 generated by the first common voltage supply unit 170 and supplied to the first active region is swinged in a frame period and is supplied with an inverted polarity.

The second common voltage Vcom2 generated by the second common voltage supply unit 180 and supplied to the second active region also swings at a frame period and is supplied with an inverted polarity.

As illustrated in FIG. 6, the first common voltage Vcom1 and the second common voltage Vcom2 have polarities opposite to each other in the same frame. As a result, common voltages (first common voltage Vcom1 and second common voltage Vcom2) having different polarities are supplied to the first active region and the second active region of the liquid crystal panel 110.

In the above description, a first common voltage supply unit 170 supplying the first common voltage Vcom1 to the first active region, and a second supply voltage of the second common voltage Vcom2 to the second active region. Although the common voltage supply unit 180 has been described as being implemented in a separate configuration, a plurality of common voltages having different polarities are generated within one frame through one common voltage supply unit, and the generated common voltages are generated by the plurality of active voltages. It may be supplied to each of the zones.

Referring to FIG. 7, a driving method of the liquid crystal display according to the exemplary embodiment of the present invention will be described.

In the Nth frame, when a common voltage having a positive polarity is supplied to the upper end with respect to the center of the liquid crystal panel 110, a common voltage having a negative polarity is supplied to the lower end.

Subsequently, when a common voltage having negative polarity is supplied to the upper end with respect to the center of the liquid crystal panel 110 in the N + 1 th frame, the common voltage having a positive polarity is supplied to the lower end.

As described above, each of the first common voltage Vcom1 and the second common voltage Vcom2 is driven in a frame inversion manner so that + Vcom and -Vcom alternate between the common electrodes of the liquid crystal panel 110. When the polarities of the first common voltage Vcom1 and the second common voltage Vcom2 are applied to the first common electrode and the second common electrode, there is a difference. That is, polarities of the first common voltage Vcom1 and the second common voltage Vcom2 are changed at different times.

In addition, the scan signal is sequentially supplied to all the gate lines, that is, sequentially from the first gate line to the last gate line. The polarity of the first common voltage Vcom1 and the second common voltage Vcom2 supplied to the first active region and the second active region during the one frame period is from positive to negative or The data voltage is supplied according to the scan signal for each data line on the basis of the time point at which the negative electrode is converted from the negative electrode to the positive electrode, thereby forming a pixel voltage in each pixel.

Here, the common voltages Vcom1 and Vcom2 supplied to each of the first active region and the second active region are converted to polarities opposite to the polarities supplied in the previous frame at the time when the data voltage is first supplied during one frame period.

As an example, in one frame period, the data voltage is supplied for each data line based on a time point when the polarity of the first common voltage Vcom1 supplied to the active region is first supplied to the active region among the entire active regions. The pixel voltage is formed in the pixel of the active region (first active region) positioned at the upper end of 110.

Meanwhile, in one frame period, the data voltage is supplied for each data line on the basis of the point in time when the polarity of the second common voltage Vcom2 supplied to the active region to which the data voltage is last supplied among the active regions is changed. The pixel voltage is formed in the pixel of the active region (second active region) positioned at the lower end of the 110.

In this case, the first light source group 142 disposed to correspond to the first active region to which the first common voltage Vcom1 is supplied remains on for the set duty ratio within one frame and then turns on to the first common region. When the polarity of the voltage Vcom1 is switched, it is turned off.

In addition, the second light source group 144 disposed to correspond to the second active region to which the second common voltage Vcom2 is supplied is kept on for the set duty ratio within one frame and then is turned on to the second common region. When the polarity of the voltage Vcom2 is changed, it is turned off.

The liquid crystal display according to the exemplary embodiment of the present invention swings the first common voltage Vcom1 and the second common voltage Vcom2 having a different polarity in a frame period, so that the liquid crystal display according to the center of the liquid crystal panel 110 may be moved. It is supplied to each lower part and driven by frame inversion method.

As a result, the display quality may be improved by preventing a vertical luminance deviation between the upper end and the lower end of the liquid crystal panel generated during frame inversion driving due to the common voltage swing. In addition, the manufacturing voltage of the liquid crystal display may be reduced by lowering the driving voltage range of the data driver.

In addition, the first light source group 142 and the first light source group 142 disposed to correspond to the upper end and the lower end of the liquid crystal panel 110 based on the timing at which the polarities of the first common voltage Vcom1 and the second common voltage Vcom2 are converted. The on-off time and duty ratio of the two light source groups 144 are controlled. Through this, display quality may be improved by improving motion blur according to the hold characteristic of the light source.

In the above description, the light source of the backlight unit 140 has been described as being applied to the direct type as shown in FIG. 5, but this is an example of the present invention. In another embodiment of the present invention, the light source may be applied in an edge type as shown in FIG. 8.

Specifically, as illustrated in FIG. 8A, the first light source group 142 and the second light source group 144 may be formed to correspond to upper and lower ends of the liquid crystal panel 110 at one side of the liquid crystal panel 110. Can be deployed. As another example, as shown in FIG. 8B, the first light source group 142 and the second light source group 144 may correspond to upper and lower ends of the liquid crystal panel 110 at both sides of the liquid crystal panel 110 as shown in FIG. 8B. This can be arranged.

In the above description, the entire active area is divided into two active areas with respect to the center of the liquid crystal panel 110, and a common voltage having different polarities is supplied to each active area within one frame. An example of the present invention has been described.

In another embodiment of the present invention, as shown in FIG. 9, the entire active area may be divided into three or more active areas, and a common voltage may be supplied to each active area. In this case, the common voltages supplied to adjacent active regions during one frame period may have different polarities, and may be swinged at frame periods to change polarities.

In another embodiment of the present invention, the same common voltage is swinged and supplied to all active regions of the liquid crystal panel at a frame period, and the on-off of the light source may be controlled based on the time point at which the data voltage is supplied.

It will be understood by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Therefore, it is to be understood that the embodiments described above are exemplary in all respects and not restrictive.

The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

100: liquid crystal display 110: liquid crystal panel
112: gate line 114: data line
120: gate driver 130: data driver
140: backlight unit 160: backlight driver
160: timing controller 170: first common voltage supply unit
180: second common voltage supply unit

Claims (10)

The entire active area of the liquid crystal panel is divided into a first active area and a second active area, and a first common voltage and a second common voltage having different polarities in the first active area and the second active area during one frame period. Supplying each;
Supplying a data voltage for each data line according to a scan signal based on a time point at which polarities of the first common voltage and the second common voltage are switched;
Turning on a first light source group disposed to correspond to the first active region and a second light source group disposed to correspond to the second active region by a duty ratio set during the one frame period; And
Turning off the first light source group when the polarity of the first common voltage is switched and turning off the second light source group when the polarity of the second common voltage is switched; A method of driving a liquid crystal display device. The method of claim 1,
And the first common voltage and the second common voltage are swinged at frame periods to switch polarities. The method of claim 1,
And wherein the polarity of the first common voltage and the second common voltage are different at different times in one frame period. The method of claim 1,
The on-off time of the first light source group is controlled based on a point in time when the polarity of the first common voltage supplied to the active region to which the data voltage is supplied for the first time among all the active regions is switched. Method of driving a liquid crystal display device. The method of claim 1,
The on-off time of the second light source group is controlled on the basis of a point in time when the polarity of the second common voltage supplied to the active region to which the data voltage is supplied last among all the active regions is switched. Method of driving a liquid crystal display device. The method of claim 1,
And driving on-off times of the first light source group and the second light source group differently. A liquid crystal panel in which all active regions are divided into a plurality of active regions;
A timing controller generates a backlight control signal for controlling the on-off time and duty ratio of the light sources and a common voltage control signal for controlling the common voltage supplied to each of the plurality of active regions. ;
A common voltage supply unit generating a common voltage based on the common voltage control signal and supplying common voltages having different polarities to adjacent active regions during one frame period;
A data driver for supplying data voltages to the pixels of the plurality of active regions on the basis of the point in time at which the polarities of the common voltages of the different polarities are converted; And
And a backlight driver configured to drive the light sources based on a time point at which polarities of the common voltages having different polarities are converted based on the backlight control signal. The method of claim 7, wherein the plurality of active regions
And a first active region corresponding to an upper end and a second active region corresponding to a lower end with respect to the center of the liquid crystal panel. The method of claim 8,
The light sources include a first light source group disposed to correspond to the first active region and a second light source group disposed to correspond to the second active region,
And the backlight driver turns on the first light source group and the second overgroup group at different times during one frame period. The method of claim 7, wherein the common voltage supply unit
The polarities of the common voltages supplied to the adjacent active regions are switched at different times during one frame period,
And converting polarities of the common voltages supplied to the adjacent active regions in frame periods.

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