KR101028343B1 - Liquid crystal display device and driving method thereof - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device which can improve the problem that an image displayed in a low gray scale area has a blue-based color.

The present invention provides a liquid crystal panel for receiving an image signal and displaying an image; A first light source emitting red light and a second light source emitting blue light; An inverter including first and second drivers configured to receive a luminance voltage and supply power to the first and second light sources, respectively, to adjust the brightness of the first and second light sources; Provided is a liquid crystal display device including a main controller for outputting an image signal to the liquid crystal panel and outputting a luminance voltage to the inverter.

The present invention uses a lamp having a high color temperature that emits light in a short wavelength region and a lamp having a low color temperature that emits light in a long wavelength region. Different adjustments. Therefore, when the low gray scale area is displayed, there is an effect of improving the appearance of the blue color.

Description

Liquid crystal display device and driving method             

1 is a view showing a liquid crystal display device.

2A and 2B are cross-sectional views showing the arrangement of liquid crystal molecules in a voltage off / on state in an IPS liquid crystal display device, respectively.

3 is a diagram illustrating transmittance for each wavelength band according to voltage application in an IPS liquid crystal display;

4 is a view showing a change in color temperature according to the gradation of an IPS LCD.

5 is a view showing an IPS liquid crystal display device according to a first embodiment of the present invention.

6 is a view showing a substrate for an IPS liquid crystal display device according to a first embodiment of the present invention.

7 illustrates a lamp of a backlight for a liquid crystal display according to a first embodiment of the present invention.

8 shows an inverter according to a first embodiment of the present invention;

9 is a view showing on-driving time of first and second lamps according to luminance voltage according to a first embodiment of the present invention;                 

10A and 10B illustrate a light emitting diode of a backlight according to a second embodiment of the present invention.

11 illustrates an inverter according to a second embodiment of the present invention.

12 is a view showing on-driving time of first, second and third light emitting diodes according to luminance voltage according to a second embodiment of the present invention;

<Description of the symbols for the main parts of the drawings>

200: IPS liquid crystal display device 210: liquid crystal panel

220: main control unit 221: panel control unit

222: inverter control unit 230: signal analysis unit

240: backlight 241: lamp

242: inverter

The present invention relates to a liquid crystal display and a driving method thereof.

As the information society develops, the demand for display devices for displaying images is increasing in various forms. Recently, liquid crystal display (LCD), plasma display panel (PDP), electro luminescent display (ELD), and VFD (vacuum) Various flat panel displays such as fluorescent displays are used.

Among flat panel displays, liquid crystal displays are widely used because they can be driven with low power and have excellent image quality.

A liquid crystal display device displays an image by using optical anisotropy and birefringence characteristics of liquid crystal molecules. When an electric field is applied, the arrangement of the liquid crystals is changed, and the characteristics of transmitting light according to the changed arrangement direction of the liquid crystals are also changed. In liquid crystal displays, two substrates on which field generating electrodes are formed are disposed so that the surfaces on which the two electrodes are formed face each other, liquid crystal is injected between the two substrates, and a voltage is generated by applying a voltage to the two electrodes. By moving the liquid crystal molecules, the device expresses an image by the transmittance of light that varies accordingly.

1 is a diagram illustrating a liquid crystal display device.

As illustrated, the liquid crystal display 11 includes a black matrix 6 formed between the red, green, and blue color filter layer 8 and the color filter layer 8, and a common electrode deposited on the color filter layer 8. An upper substrate 5 having the 18 formed thereon, a pixel region P is defined, and a pixel electrode 17 and a switching element T are formed in the pixel region P, and array wiring is provided around the pixel region P. The lower substrate 22 is formed, and the liquid crystal 14 is filled between the upper substrate 5 and the lower substrate 22.

 The lower substrate 22 is also called an array substrate, and the thin film transistor T, which is a switching element, is positioned in a matrix type, and the gate wiring 13 passing through the plurality of thin film transistors TFT is crossed. And data wiring 15 is formed. In this case, the pixel region P is a region defined by the intersection of the gate wiring 13 and the data wiring 15. A transparent pixel electrode 17 is formed on the pixel region P as described above.

The pixel electrode 17 uses a transparent conductive metal having relatively high light transmittance, such as indium-tin-oxide (ITO). A storage capacitor C _ST connected in parallel with the pixel electrode 17 is formed on the gate wiring 13, and a portion of the gate wiring 13 is used as the first electrode of the storage capacitor C _ST . As the second electrode, an island-shaped source / drain metal layer 30 formed of the same material as the source and drain electrodes is used.

In this case, the source / drain metal layer 30 is configured to be in contact with the pixel electrode 17 to receive a signal of the pixel electrode.

In the liquid crystal display having the above configuration, the electric field generated by the pixel electrode and the common electrode forms a vertical electric field perpendicular to the substrate surface, and drives the liquid crystal by the vertical electric field. A liquid crystal display device driven by a vertical electric field has a disadvantage of having a narrow viewing angle.

In order to improve the viewing angle deterioration due to the vertical electric field, an in-plane switching mode (IPS) for driving the liquid crystal by a transverse electric field parallel to the substrate surface is used. In the lateral electric field method, the common electrode and the pixel electrode are formed on the same substrate, thereby forming a horizontal electric field in the liquid crystal layer. Such an IPS liquid crystal display device is widely used because of its excellent viewing angle characteristics.                         

2A and 2B are cross-sectional views showing the arrangement of liquid crystal molecules in a voltage off / on state in an IPS liquid crystal display device, respectively.

In the voltage-off state, as shown in FIG. 2A, since no electric field is applied to the liquid crystal molecules 50, the liquid crystal molecules 50 are maintained in the initial arrangement state.

In the voltage-on state, as shown in FIG. 2B, since a vertical electric field is formed on the common electrode 38 and the pixel electrode 40, the liquid crystal molecules 50a positioned therein have no change in the arrangement direction, but the common electrode 38 ) And the liquid crystal molecules 50b positioned between the pixel electrode 40 have an operating characteristic arranged in parallel with the substrate by a horizontal electric field generated between the common electrode 38 and the pixel electrode 40.

On the other hand, the liquid crystal display device is a non-light emitting display device, and receives light from a backlight which is a light source to display an image. The backlight emits light having a wavelength (380 to 780 nm) corresponding to the visible light region and supplies the light to the liquid crystal display, and the supplied light is refracted by driving the liquid crystal to display an image.

3 is a diagram illustrating transmittance for each wavelength band according to voltage application in an IPS liquid crystal display.

As shown, as the applied voltages V1, V2, and V3 decrease, the peak point of the transmittance for light emitted by the backlight moves to the short wavelength region.

In the IPS liquid crystal display, which is driven in a normally black mode, as the driving voltages V1, V2, and V3 increase, the image of a high gray level region becomes closer to white. As the applied voltages V1, V2, and V3 are lowered, the closer the image is to black, the lower grayscale image is displayed. Therefore, when the applied voltages V1, V2, and V3 are decreased to express low gray levels, the transmission ratio of light corresponding to the short wavelength region is increased.

4 is a diagram illustrating a change in color temperature according to the gradation of an IPS liquid crystal display.

As shown in the figure, the transmission ratio of light in the short wavelength region is increased as the grayscale is moved, and the color temperature (CCT: Correlated Color Temperature) can be seen to increase rapidly. In other words, as the grayscale moves to a lower gray level, the transmission ratio of the blue light, which is light corresponding to the short wavelength region, is relatively increased.

Therefore, the color of an image displayed in a low gray scale area is bluish, and a problem occurs in that the color of a blue series is prominent for an image displaying black.

An object of the present invention for solving the above problems is to provide a liquid crystal display device that can improve the problem that the image displayed in the low gray scale region has a blue color.

In order to achieve the above object, the present invention provides a liquid crystal panel for receiving an image signal and displaying an image; A first light source emitting red light and a second light source emitting blue light; An inverter including first and second drivers configured to receive a luminance voltage and supply power to the first and second light sources, respectively, to adjust the brightness of the first and second light sources; Provided is a liquid crystal display device including a main controller for outputting an image signal to the liquid crystal panel and outputting a luminance voltage to the inverter.

Here, the on driving time of the first light source may be more than the on driving time of the second light source.

The light source may further include a third light source for emitting green light.

In addition, the light source may be one selected from a lamp and a light emitting diode.

The liquid crystal panel may include first and second substrates facing each other, a liquid crystal interposed between the first and second substrates, and the first substrate may include gate wirings and data wirings intersecting with each other, the gate wirings and The thin film transistor may include a thin film transistor positioned at an intersection of the data lines, a pixel electrode connected to the thin film transistor, and a common electrode spaced in parallel with the pixel electrode.

The apparatus may further include an analyzer configured to adjust the luminance voltage by analyzing a frequency of grayscales of the image signal.

The main controller may include a panel controller which outputs an image signal to the liquid crystal panel, and an inverter controller which outputs a luminance voltage to the inverter.

In another aspect, the present invention includes the steps of adjusting the luminance voltage input to the inverter; Driving the first and second light sources by supplying power to a first light source emitting red light and a second light source emitting blue light according to an input luminance voltage; A liquid crystal display device driving method includes displaying an image by receiving an image signal and light emitted by the first and second light sources.

Here, the on driving time of the first light source may be more than the on driving time of the second light source.

The method may further include adjusting the luminance voltage by analyzing a frequency of grayscales of the image signal.

The method may further include driving the third light source by supplying power to a third light source emitting green light.

The present invention uses a lamp having a high color temperature that emits light in a short wavelength region and a lamp having a low color temperature that emits light in a long wavelength region. Different adjustments. Therefore, when the low gradation region is displayed, it is possible to improve the appearance of the blue system.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>

FIG. 5 is a diagram illustrating an in-plane switching mode (IPS) liquid crystal display device according to a first embodiment of the present invention. FIG. 6 is a view showing a substrate for an IPS liquid crystal display device according to a first embodiment of the present invention, and FIG. 7 is a view showing a lamp of a backlight for a liquid crystal display device according to a first embodiment of the present invention. . 8 is a view showing an inverter according to the first embodiment of the present invention.

As shown in FIG. 5, the IPS liquid crystal display 200 according to an exemplary embodiment of the present invention includes a liquid crystal panel 210 for displaying an image, an analyzer 230 for analyzing the frequency of gray levels of the image, and a liquid crystal. It includes a backlight 240 for supplying light to the panel 210, and a main controller 220 for controlling the driving of the liquid crystal panel 210 and the backlight 240.

In the liquid crystal panel 210, a plurality of pixels P are arranged in a matrix form, and each pixel P is connected to the gate lines and the data lines GL and DL to be turned on / off and driven by a thin film transistor T. A liquid crystal capacitor (C _LC ) in which an image signal is charged according to on / off driving of the film transistor and the thin film transistor T is positioned. On the other hand, a storage capacitor (not shown) may be further configured to improve the image signal charging characteristic of the pixel P.

The liquid crystal panel 210 includes a color filter substrate facing each other, an array substrate, and a liquid crystal (not shown) filled between the two substrates. In the array substrate, a pixel electrode and a common electrode are formed to apply a transverse electric field to the liquid crystal.

As shown in FIG. 6, a gate line and a data line GL and DL are formed on an array substrate for a liquid crystal display device that is a lower substrate of the liquid crystal panel 210 to define pixels P orthogonal to each other. The thin film transistor T connected to the wiring and the data lines GL and DL is formed. The thin film transistor T is connected to the pixel electrode PE, and the common electrode CE is connected to the common line CL. When the thin film transistor T is turned on, the pixel electrode PE and the common electrode CE formed in parallel with each other form a transverse electric field E.

The backlight 240 includes a lamp 241 that emits light and an inverter 242 that drives the lamp 241 by transferring power to the lamp 241.

As illustrated in FIG. 7, a plurality of lamps 241 are arranged in parallel under the liquid crystal panel 210 in a direct type manner. The first lamp 241a having a low color temperature emitting light in the long wavelength region in the visible light region and the second lamp 241b having high color temperature for emitting light in the short wavelength region are alternately arranged. The first lamp 241a emits light in a long wavelength region having a low color temperature, that is, red series, and the second lamp 242b emits light in a short wavelength region having a high color temperature, that is, a blue series.

The lamp 241 is driven on or off (ie, turned on and off) for a predetermined time by the inverter 242 which is the lamp driver 242. The brightness of light is determined according to the on driving time of the lamp 241. The on driving time of the lamp 241 is increased to emit light of high brightness, and the on driving time of the lamp is emitted to emit light of low brightness. Keep it short The gradation of the displayed image is also determined according to the on driving time of the lamp 241.

The inverter 242, which is the lamp driver 242, transfers power to the first and second lamps 241a and 241b according to the luminance voltage Vbr input thereto, and turns on each of the first and second lamps 241a and 241b. ) Adjust the driving time.                     

As shown in FIG. 8, the inverter 242 transfers the first power source P1 to the first lamp 241a according to the luminance voltage Vbr to drive the first lamp 241a. ) And a second driver 243b for transmitting the second power source P2 to the second lamp 241b to drive the second lamp 241b. The first and second driving units 243a and 243b transmit the first and second power sources P1 and P2 to the first and second lamps 241a and 241b, respectively, so that the driving time of the first and second lamps 241a and 241b is turned on. Will be adjusted.

When a high luminance voltage Vbr is input to the inverter 242 to display a high luminance image, the on-driving time of the first and second lamps 241a and 241b is long by the first and second driving units 243a and 243b. When the low luminance voltage Vbr is input to the inverter 242 to display a low luminance image, the first and second drivers 243a and 243b drive the first and second lamps 241a and 241b on. The time will be shorter.

In particular, the inverter 242 varies the on-driving time of the first and second lamps 241a and 241b according to the luminance voltage Vbr.

9 is a diagram illustrating on driving times of first and second lamps according to luminance voltages according to the first exemplary embodiment of the present invention.

The on-driving time of the first lamp (see 241a in FIG. 8) by the first driver (see 243a in FIG. 8) follows the first on-drive line L1. That is, when the luminance voltage Vbr moves from the minimum luminance voltage MIN to the maximum luminance voltage MAX, the on-driving time ratio α of the first lamp is monotonically increased from LR% to 100%. Here, the maximum luminance voltage MAX is for displaying white which is the highest gray level, and the minimum luminance voltage MIN is for displaying black which is the lowest gray level. When the luminance voltage Vbr is at any luminance voltage INT, the on-driving time ratio α of the first lamp has a relationship such as LR% ≦ α ≦ 100%.

The on-driving time of the second lamp (see 241b in FIG. 8) by the second driver (see 243b in FIG. 8) is along the second on-drive line L2. That is, when the luminance voltage Vbr moves from the minimum luminance voltage MIN to the maximum luminance voltage MAX, the on-driving time ratio β of the second lamp monotonically increases from LB% to 100%. When the luminance voltage Vbr is at any luminance voltage INT, the on-driving time ratio β of the second lamp has a relationship such as LB% ≦ β ≦ 100%.

When the luminance voltage Vbr is the maximum luminance voltage MAX, the on-driving time ratios α and β of the first and second lamps are the same, and when the luminance voltage Vbr is the minimum luminance voltage MIN Since the on driving time of the first lamp is greater than the on driving time of the second lamp, the first on driving line L1 has a lower slope than the second on driving line L2. Therefore, when the luminance voltage Vbr is less than the maximum luminance voltage MAX, the on driving time ratio α of the first lamp is greater than the on driving time ratio β of the second lamp, in particular, the luminance voltage Vbr. As the maximum luminance voltage MAX moves from the maximum luminance voltage MAX to the minimum luminance voltage MIN, the difference between the on driving time ratio α of the first lamp and the on driving time ratio β of the second lamp increases.

As the luminance voltage Vbr moves to the minimum luminance voltage MIN and moves to a low gray scale region, the on driving time ratio α of the first lamp is made larger than the on driving time ratio β of the second lamp. The luminance of light in the long wavelength region of the series is increased to be higher than the luminance of light in the short wavelength region of the blue series. Therefore, it is possible to improve that the image exhibits the blue color in the low gradation region.

As the luminance voltage Vbr increases, the on-driving time ratios α and β of the first and second lamps increase, respectively, and as the luminance voltage Vbr decreases, the on-driving time of the first and second lamps. The ratios alpha and beta respectively decrease. Therefore, the difference between the luminance of the image in the high gradation region and the luminance of the image in the low gradation region becomes large, and the contrast ratio of the image increases.

As shown in FIG. 5, the analysis unit 230 analyzes the frequency of the gray level of the input image signal Ds input from the signal input system 300 during one frame to control the signals IC and YC. It is output to the main control unit 220. The analyzer 230 counts the gray levels of the input image signal Ds and analyzes the frequency of the gray levels of the input image signal Ds.

The main controller 220 includes a panel controller 221 controlling the driving of the liquid crystal panel 210 and an inverter controller 222 controlling the driving of the inverter 242.

The panel controller 221 outputs various control signals and image signals D to the liquid crystal panel 210 to drive the liquid crystal panel 210. The panel controller 221 converts the input image signal Ds according to the image control signal IC output by the analyzer 230, and outputs the converted output image signal D to the liquid crystal panel 210. Done.

By the analysis of the analysis unit 230, when there are many low gray levels, the gray level of the output image signal D is further lowered, and when there are many high gray levels, the gray level of the output image signal D is further increased.                     

The inverter controller 222 outputs various control signals and luminance voltages Vbr to the inverter 242 to drive the inverter 242.

The luminance voltage Vbr is adjusted according to the luminance control signal YC output by the analyzer 230. By the analysis of the analysis unit 230, the luminance voltage Vbr is lowered when there are many low gray levels, and the luminance voltage Vbr is increased when there are many high gray levels.

Therefore, by adjusting the signal D gray level and the luminance voltage Vbr of the output image, the contrast ratio of the dark image with many low tones and the bright image with many tones is increased.

As described above, the liquid crystal display according to the first exemplary embodiment of the present invention has a lamp having a low color temperature emitting red light of a long wavelength region and a lamp having a high color temperature emitting blue light of a short wavelength region. By adjusting the brightness of a lamp having a low color temperature higher than the brightness of a lamp having a high color temperature in the case of displaying an image of a low gray scale area, it is possible to improve that the image of a low gray scale area has a blue-based color. Can be.

&Lt; Embodiment 2 >

In the second embodiment of the present invention, a light emitting diode (LED) emitting red, green, and blue light is used instead of a lamp as a light source of a backlight. In the second embodiment of the present invention, description of the same or corresponding matters as the first embodiment of the present invention will be omitted.

10A and 10B illustrate a light emitting diode of a backlight according to a second embodiment of the present invention. 11 is a diagram illustrating an inverter according to a second embodiment of the present invention.

As shown in Figs. 10A and 10B, the first, second and third light emitting diodes 341a, 341b and 341c respectively emitting red, green and blue light are alternately arranged on the substrate 349. . The first light emitting diode 341a has a low color temperature to emit light in a long wavelength region in the visible light region, and the third light emitting diode 341c has a high color temperature to emit light in a short wavelength region and a second light emitting diode 341b ) Has a medium color temperature and emits light in the intermediate wavelength range. The light emitting diode 341 is connected to and driven by an inverter through a lead wire (not shown) arranged on the substrate 349.

The substrate 349 on which the light emitting diodes 341 are arranged is embedded between the first and second reflecting plates 345 and 346 under the liquid crystal panel 310 to supply light to the liquid crystal panel 310 in an edge manner. do. The first reflecting plate 345 has a planar shape, and the second reflecting plate 346 has an edge spaced apart from the first reflecting plate 345 so that the light emitting diode 341 is embedded. The light emitting diode 341 emits light toward an outer surface of the second reflecting plate 346, and the emitted light passes through the first light guide plate 347 imparted between the first and second reflecting plates 345 and 346. The second reflecting plate 346 is reflected by the inner surface and passes through the second light guide plate 348. The first LGP 347 lengthens the light guiding path (arrow of FIG. 10A) of the light emitted through the light emitting diode 341 so that the colors are sufficiently mixed. Light guided through the second light guide plate 348 is reflected through the first reflective plate 345 and supplied to the liquid crystal panel 310.

As shown in FIG. 11, the first power source P1 is transferred to the inverter 342, which is the light emitting diode driver 342, according to the luminance voltage Vbr, to the first light emitting diode 341a, thereby providing a first light emitting diode ( A first driver 343a for driving 341a, a second driver 343b for transmitting the second power source P2 to the second light emitting diode 341b to drive the second light emitting diode 341b, and a third A third driver 343c is configured to transfer the third power source P3 to the light emitting diode 341c to drive the third light emitting diode 341c. The first, second, and third driving units 343a, 343b, and 343c transfer the first, second, and third power sources P1, P2, and P3 to the first, second, and third light emitting diodes 341a, 341b, and 341c, respectively. The on-driving time of the 1, 2, 3 light emitting diodes 341a, 341b, and 341c is adjusted.

When the high luminance voltage Vbr is input to the inverter 342 to display an image of high luminance, the first, second and third light emitting diodes 341a and 341b are driven by the first, second and third driving units 343a, 343b and 343c. When the low luminance voltage Vbr is input to the inverter 342 in order to display an image of low luminance, the first, second, and third driving units 343a, 343b, and 343c The on driving time of the first, second, and third light emitting diodes 341a, 341b, and 341c is shortened.

In particular, the inverter 342 changes the on-driving time of the first, second, and third light emitting diodes 341a, 341b, and 341c according to the luminance voltage Vbr.

FIG. 12 is a diagram illustrating on driving times of first, second and third light emitting diodes according to luminance voltages according to a second exemplary embodiment of the present invention.                     

The on driving time of the first light emitting diode (see 341a in FIG. 11) is along the first on driving line L1 by the first driver (see 343a in FIG. 11). That is, when the luminance voltage Vbr moves from the minimum luminance voltage MIN to the maximum luminance voltage MAX, the on-driving time ratio α of the first light emitting diode monotonically increases from LR% to 100%. When the luminance voltage Vbr is at any luminance voltage INT, the on-driving time ratio α of the first light emitting diode has a relationship such as LR% ≦ α ≦ 100%.

The on driving time of the second light emitting diode (see 341b of FIG. 11) is along the second on driving line L2 by the second driver (see 343b of FIG. 11). That is, when the luminance voltage Vbr moves from the minimum luminance voltage MIN to the maximum luminance voltage MAX, the on-driving time ratio of the second light emitting diode monotonically increases from LG% to 100%. When the luminance voltage Vbr is at any luminance voltage INT, the on-driving time ratio γ of the second light emitting diode has a relationship such as LG% ≦ γ ≦ 100%.

The on driving time of the third light emitting diode (see 341c of FIG. 11) is along the third on driving line L3 by the third driver (see 343c of FIG. 11). That is, when the luminance voltage Vbr moves from the minimum luminance voltage MIN to the maximum luminance voltage MAX, the on-driving time ratio of the third light emitting diode monotonically increases from LB% to 100%. When the luminance voltage Vbr is at any luminance voltage INT, the on-driving time ratio β of the third light emitting diode has a relationship such as LB% ≦ β ≦ 100%.

When the luminance voltage Vbr is the maximum luminance voltage MAX, the on driving time ratios α, γ, and β of the first, second and third light emitting diodes are the same, and the luminance voltage Vbr is the minimum luminance voltage ( MIN), the on driving time of the first light emitting diode is greater than the on driving time of the second light emitting diode, and the on driving time of the third light emitting diode is located between the driving times of the first and second light emitting diodes. The driving line L1 has a lower slope than the third on driving line L3, and the slope of the second on driving line L2 is between the slopes of the first and third driving lines L1 and L3. Therefore, when the luminance voltage Vbr is less than the maximum luminance voltage MAX, the on driving time ratio α of the first light emitting diode is greater than the on driving time ratio β of the third light emitting diode, and in particular, the luminance voltage ( As Vbr moves from the maximum luminance voltage MAX to the minimum luminance voltage MIN, the difference between the on driving time ratio α of the first light emitting diode and the on driving time ratio β of the third light emitting diode increases.

As the luminance voltage Vbr moves to the minimum luminance voltage MIN and moves to a low gray scale region, the on driving time ratio α of the first light emitting diode is made larger than the on driving time ratio β of the third LED. In addition, the luminance of light in the long wavelength region of the red series is increased than the luminance of light in the short wavelength region of the blue series. Therefore, it is possible to improve that the image exhibits blue-based color in the low gradation region.

The second light emitting diode emits green light, which is an intermediate wavelength region, and the on driving time ratio γ of the second light emitting diode is between the on driving time ratios α and β of the first and third light emitting diodes. The color is adjusted so that light is not biased to blue or red color in all gray areas.

As described above, the liquid crystal display according to the second exemplary embodiment of the present invention has a light emitting diode having a low color temperature emitting red light of a long wavelength region and a high color temperature emitting light of a blue series of a short wavelength region. By using a light emitting diode and adjusting the luminance of a lamp having a low color temperature higher than the luminance of a lamp having a high color temperature when displaying an image of a low gray scale region, it is possible that the image of a low gray scale region has a blue-based color. By using a light emitting diode having an intermediate color temperature that emits light of the green series, which is an intermediate wavelength region, an image has an even color distribution in all the gradation regions without biasing the blue or red colors.

In the exemplary embodiment of the present invention as described above, a light emitting diode emitting red and blue light, and a light emitting diode emitting red and blue light and green light, respectively, are exemplified. However, the present invention is not limited thereto. Do not. For example, lamps emitting red, blue and green light may be alternately used, and light emitting diodes emitting red and blue light may be used. In addition, other light emitting means capable of emitting red and blue light and the like can be used.

Embodiment of the present invention as described above is an example of the present invention, various modifications are possible. When such modifications are included in the spirit of the present invention, it is obvious to those skilled in the art that they fall within the scope of the present invention. The scope of the invention will be apparent from the claims.

The present invention uses a lamp having a high color temperature that emits light in a short wavelength region and a lamp having a low color temperature that emits light in a long wavelength region. Different adjustments. Therefore, when the low gray scale area is displayed, there is an effect of improving the appearance of the blue color.

Claims (11)

A liquid crystal panel which receives an image signal and displays an image; A first light source emitting red light and a second light source emitting blue light; An inverter including first and second drivers configured to receive a luminance voltage and supply power to the first and second light sources, respectively, to adjust the brightness of the first and second light sources; A main controller which outputs an image signal to the liquid crystal panel and outputs a luminance voltage to the inverter; And an analyzer configured to adjust the luminance voltage by analyzing a frequency of grayscales of the image signal, wherein an on-drive time of the first light source is greater than an on-drive time of the second light source, and the luminance voltage is determined by analysis of the analyzer. The liquid crystal display device, characterized in that the difference between the on-driving time of the first light source and the second light source is larger from maximum to minimum. delete The method of claim 1, A liquid crystal display further comprising a third light source for emitting green light. The method of claim 1, And the first and second light sources are one selected from a lamp and a light emitting diode. The method of claim 1, The liquid crystal panel includes first and second substrates facing each other, a liquid crystal interposed between the first and second substrates, and the first substrate includes a gate wiring and a data wiring crossing each other, and the gate wiring and a data wiring. And a thin film transistor positioned at the crossing portion, a pixel electrode connected to the thin film transistor, and a common electrode spaced in parallel with the pixel electrode. delete The method of claim 1, The main control unit includes a panel controller which outputs an image signal to the liquid crystal panel, and an inverter controller which outputs a luminance voltage to the inverter. Adjusting a luminance voltage input to the inverter; Driving the first and second light sources by supplying power to a first light source emitting red light and a second light source emitting blue light according to an input luminance voltage; Displaying an image by receiving an image signal and light emitted by the first and second light sources; Analyzing the frequency of the gray level of the image signal in the analyzer to adjust the luminance voltage The on driving time of the first light source is greater than the on driving time of the second light source, and the difference between the on driving time of the first light source and the second light source as the luminance voltage increases from the maximum to the minimum by the analysis unit. It is characterized in that the larger liquid crystal display device driving method. delete delete The method of claim 8, And driving the third light source by supplying power to a third light source emitting green light.

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