KR101676245B1 - Liquid crystal display device and driving method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display capable of automatically controlling a dimming signal of a backlight according to a change in gain of image data and a driving method thereof.

A liquid crystal display device according to an embodiment of the present invention includes a liquid crystal panel for controlling an optical transmittance of a liquid crystal according to an input image data signal to display an image; A backlight for supplying light to the liquid crystal panel; A backlight driver for driving the backlight; A timing controller for converting an input video signal into a video data signal in a frame unit and supplying the video data signal to the liquid crystal panel and the backlight driving unit; And a parameter generator for adjusting a gain value of the image data signal according to a request for changing the dimming signal range for driving the backlight from a user and changing a parameter of a maximum dimming value and a dimming point for driving the backlight do.

Backlight, dimming, gamma, gain,

Description

TECHNICAL FIELD [0001] The present invention relates to a liquid crystal display (LCD)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display capable of automatically controlling a dimming signal of a backlight according to a change in gain of image data and a driving method thereof.

An active matrix type liquid crystal display device displays an image by adjusting a light transmittance of a liquid crystal through a thin film transistor (TFT) as a switching element. Such a liquid crystal display device is applied to portable information equipment, office equipment, computer and IT products due to advantages such as light weight, thin shape and low power consumption driving, and its application range is widening.

Since the liquid crystal display device is not a self-luminous device, images are displayed using light supplied through a backlight unit provided under the liquid crystal panel. When the transmittance of light passing through the liquid crystal layer of the liquid crystal panel is maximized, the liquid crystal panel realizes a white image with high brightness. When the transmittance of light of the liquid crystal layer is minimized, .

Referring to FIG. 1, a liquid crystal display typically displays an image by irradiating light at a maximum luminance in a backlight unit and adjusting the amount of light transmitted through the backlight unit according to an electric field applied in units of a unit cell in a liquid crystal panel. Therefore, in the case of the general driving, the luminance of the image displayed on the liquid crystal panel varies depending on the light transmission amount of the liquid crystal cell, that is, the image data supplied to the liquid crystal panel.

Background Art Recently, as the importance of low power consumption and DCR (Dynamic Contrast Ratio) has increased, global dimming, local dimming, and so on, which are driven by the brightness of image data Data and backlight, There is a growing interest in dynamic driving methods such as optical power control.

The luminance of the image displayed on the liquid crystal panel depends on the luminance of the liquid crystal emitted from the backlight. In order to display the brightness of the image displayed on the liquid crystal panel with the original brightness in a state where the dimming signal is reduced to reduce the brightness of the light irradiated from the backlight as in the dynamic driving method, Should be increased.

In this case, the light transmittance of the liquid crystal panel is increased even when the brightness of the light emitted from the backlight is reduced, so that the user can feel the image displayed on the liquid crystal panel at the original brightness. To this end, all the image data within one frame is changed by using a gain which is a weight of image data. Therefore, the larger the gain reflected in the image data, the larger the range (variable range) of the image data, and the larger the range of the dimming signal for adjusting the luminance of the backlight.

As described above, since the variation of the image data becomes large when the gain is increased, the gain of the image data and the backlight of the image data, considering the side effect and the trade off that may occur at high luminance or low luminance, It is necessary to appropriately adjust the range of the dimming signal.

In order to set the dimming range of the backlight, it is necessary to calculate the gain corresponding to the dimming signal range and set the maximum dimming value, the minimum dimming value and the dimming point of the dimming signal of the backlight according to the gain You must give. The gamma curve is adjusted by setting the backlight luminance using a pulse width modulation (PWM) method according to the dimming signal range of the backlight depending on the gain.

In the liquid crystal display according to the related art, the engineer inputs one of the parameters of the gain of the image data and the dimming signal range into the register of the timing controller for driving the liquid crystal panel, Is reinterpreted to drive the gamma curve.

As shown in FIG. 2, when the maximum gain set initially by the engineer is set, the dimming of the backlight is varied according to the dimming point corresponding to the maximum gain. When the maximum gain value is set to 4.25, 7. Here, the dimming point means a specific gray, and the dimming point is multiplied by a gain, which is a weight of image data, to determine the luminance displayed on the liquid crystal panel.

Accordingly, in order to vary the dimming signal range of the backlight in a specific range, the maximum gain value corresponding thereto must be set. If the maximum gain value is changed, the dimming signal range and the dimming point of the backlight are changed. There is a possibility that a problem may be caused.

In order to prevent the gamma curve from being distorted, it is necessary to change the dimming signal range of the backlight and the parameters of the dimming point as well as changing the image data according to the change of the gain. For example, when driving the backlight while driving the backlight within 20% to 70% of the maximum luminance, increasing the gain value of the image data corresponding to the reduced luminance of the backlight, for example, It should be increased from the existing 4.25 to 6.5.

If the gain and the range of the dimming signal and the dimming point are not properly adjusted, the gamma curve that affects the brightness of the image data is distorted. In the liquid crystal display according to the related art, the parameters of the gain and the dimming signal range There is a problem in that the engineer has to directly change the values corresponding to the respective dimming points to match the gamma curve.

Particularly, in the liquid crystal display according to the related art, when a user who views an image desires a display mode that requires a display quality suited to his or her taste by adjusting the range of the gain and the dimming signal, or a driving mode capable of reducing power consumption, The present invention does not specifically describe a configuration and a method for adjusting the gain and the range of the dimming signal to an appropriate value while preventing the distortion.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and it is an object of the present invention to provide a liquid crystal display device and a liquid crystal display device capable of controlling the dimming of the backlight without limitation on the type, quantity and characteristics of the backlight by automatically controlling the dimming variable range of the backlight according to the user's selection. And a method thereof.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device and a driving method capable of controlling gain of image data and dimming of backlight without changing gamma which affects display quality do.

The present invention provides a liquid crystal display device and a driving method capable of providing a display quality suitable for a user's taste by controlling gain of image data and dimming of a backlight according to a user's selection .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device and a driving method capable of reducing power consumption by automatically controlling dimming of a backlight according to a change in gain of image data.

According to an aspect of the present invention, there is provided a liquid crystal display device including: a liquid crystal panel that displays an image by controlling a light transmittance of a liquid crystal according to an input image data signal; A backlight for supplying light to the liquid crystal panel; A backlight driver for driving the backlight; A timing controller for converting an input video signal into a video data signal in a frame unit and supplying the video data signal to the liquid crystal panel and the backlight driving unit; And a parameter generator for adjusting a gain value of the image data signal according to a request for changing the dimming signal range for driving the backlight from a user and changing a parameter of a maximum dimming value and a dimming point for driving the backlight .

The parameter generator of the liquid crystal display according to the embodiment of the present invention is characterized in that it calculates the ratio of the maximum dimming value included in the dimming signal range to the previously stored previous maximum dimming value to generate a new maximum dimming value .

The parameter generator of the liquid crystal display according to the embodiment of the present invention generates a new dimming point using the new maximum dimming value and the previous dimming point of each gray of the preset stored image.

The parameter generator of the liquid crystal display according to the embodiment of the present invention generates a new dimming point for each gray of the image to be displayed on the liquid crystal panel by using the new maximum dimming value and the previously stored previous dimming point .

The parameter generator of the liquid crystal display according to the exemplary embodiment of the present invention generates a new gain value weighted to the image data signal using the minimum dimming value included in the dimming signal range and the new dimming point .

The backlight driver of the liquid crystal display according to the embodiment of the present invention drives the backlight to display a certain range of brightness using the new maximum gain value and a new dimming point.

A driving method of a liquid crystal display according to an embodiment of the present invention is a driving method of a liquid crystal display that converts an image signal input from the outside into a video data signal of a frame unit suitable for driving a liquid crystal panel and displays an image on a liquid crystal panel A new maximum dimming value for driving the backlight based on the maximum dimming value included in the dimming signal lane and a new dimming value for driving the backlight when a dimming signal range for controlling the brightness of the backlight is inputted from a user viewing the image displayed on the liquid crystal panel, Generating a point; Generating a new maximum gain value weighted to the image data using the minimum dimming value included in the dimming signal lane and the new dimming point; Converting the new maximum dimming value, the new dimming point, and the new maximum gain value into a form that can be stored in a memory and storing the same in the memory; And adding the new maximum dimming value, the new dimming point, and the new maximum gain value to the video data signal of the frame unit.

According to another aspect of the present invention, there is provided a method of driving a liquid crystal display, including: driving a backlight to display a predetermined range of luminance using a video data signal including a maximum dimming value and a dimming point; And driving the liquid crystal panel using the image data signal including the maximum gain value.

The liquid crystal display device and the driving method according to the embodiment of the present invention can control the dimming value of the backlight without limitation on the type, quantity and characteristics of the backlight by automatically controlling the variable range of the backlight according to the user's selection.

The liquid crystal display device and the driving method according to the embodiment of the present invention can control the gain of the image data and the dimming value of the backlight without changing the gamma which affects the display quality.

The liquid crystal display device and the driving method according to the embodiment of the present invention can provide the display quality suitable for the user's taste by controlling the gain of the image data and the dimming value of the backlight according to the user's selection.

The liquid crystal display device and the driving method according to the embodiment of the present invention can reduce the power consumption by automatically controlling the dimming of the backlight according to the change of the gain of the image data.

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

FIG. 3 is a diagram illustrating a liquid crystal display according to an embodiment of the present invention, and FIG. 4 is a diagram illustrating a parameter generator of a liquid crystal display according to an embodiment of the present invention.

3 and 4, a liquid crystal display according to an exemplary embodiment of the present invention includes a timing controller 110, a data driving circuit 120, a gate driving circuit 130, a liquid crystal panel 140, a backlight driving unit 150, a backlight unit 160, and a parameter generator 200 embedded in the timing controller 110.

The liquid crystal panel 140 includes a thin film transistor (FTF) 142 formed in each pixel region defined by a plurality of data lines DL and a plurality of gate lines GL, a liquid crystal capacitor connected to the thin film transistor 142, And a capacitor. The liquid crystal capacitor is composed of a pixel electrode connected to the thin film transistor and a common electrode facing the pixel electrode with the liquid crystal therebetween.

 The thin film transistor 142 supplies a data voltage from each data line DL to the pixel electrode in response to a gate voltage from each gate line GL. The liquid crystal capacitor realizes a desired image by charging the difference voltage between the data voltage supplied to the pixel electrode and the common voltage supplied to the common electrode, and adjusting the light transmittance of the liquid crystal according to the difference voltage.

The storage capacitor holds the voltage charged in the liquid crystal capacitor until the next data voltage is supplied. The storage capacitor may be formed by overlapping the pixel electrode and the previous gate line, or may be formed by overlapping the pixel electrode and the storage line, And may be formed by overlapping the common electrode lines.

The gamma reference voltage generator (not shown) generates positive and negative gamma reference voltages GMA1 to GMA14 using the input power supply voltage VDD and supplies the gamma reference voltages GMA1 to GMA14 to the data driving circuit 120. [

The data driving circuit 120 latches the image data signals R ', G', and B 'input from the timing controller 110 and outputs the analog positive / negative reference gamma voltages Converts the latched image data signal into a positive / negative polarity analog data voltage, generates an analog image data voltage having a polarity corresponding to the polarity control signal POL, and supplies the analog image data voltage to the data lines DL .

To this end, the data driving circuit unit 120 may include a plurality of data driver integrated circuits including a shift register, a latch, a digital-analog conversion unit, and an output buffer (not shown). The data driving circuit unit 120 may be electrically connected to the lines of the liquid crystal panel 140 through a tape carrier package (TCP), or may be formed in the manufacturing process of the liquid crystal panel 140 And may be formed on the substrate of the liquid crystal panel 140 at the same time.

Here, the image data signals R ', G', and B 'are image data signals whose gain is changed by a parameter generator 200 described below when a mode (dimming signal range selection) is input from a user. When the gain of the image data signal is changed, the image data supplied to the liquid crystal panel 140 is changed and the light transmittance of the liquid crystal is changed. For example, when the gain is increased, the gray level of the image data supplied to the liquid crystal panel 140 varies. Accordingly, when the gain of the liquid crystal panel 140 increases, the amount of light transmitted from the backlight unit increases, and when the gain decreases, the amount of light transmitted from the backlight unit decreases.

Here, one consideration is that since the gamma curve may be distorted when the light transmittance is changed according to the change of the gain, the parameters of the dimming signal for driving the backlight must be changed in order to prevent the gamma curve from being distorted do.

That is, in order to maintain the brightness of the screen viewed by the user even if the gain is changed, the brightness of the backlight is adjusted by changing the dimming signal of the backlight as the light transmittance of the liquid crystal panel 140 is increased. At this time, the brightness of the backlight is adjusted according to the range of the dimming signal (the maximum dimming value and the minimum dimming value) and the dimming point, so that the parameter generator 200, which will be described later, The parameters of the point are changed to prevent the gamma curve from turning.

The gate driving circuit 130 generates a gate voltage in accordance with the gate control signal GCS and the gate shift clock GSC from the timing controller 110 and sequentially supplies the generated gate voltage to the gate lines GL do. At this time, the gate driving circuit unit 130 determines the level of the gate voltage according to the gate high voltage VGH and the gate low voltage VGL.

The gate driving circuit unit 130 may include a plurality of gate driver integrated circuits including a level shifter for converting the output signals of the shift register and the shift register into a swing width suitable for driving the thin film transistor 142 . The gate driving circuit unit 130 may be electrically connected to the gate line of the liquid crystal panel 140 through a tape carrier package TCP or may be formed at the same time when the thin film transistor 142 is formed during the manufacturing process of the liquid crystal panel 140. [ (Not shown).

The common voltage generating unit, not shown, receives the high voltage supply voltage VDD to generate the common voltage Vcom and supplies the generated common voltage Vcom to the liquid crystal cell Clc formed in each pixel of the liquid crystal panel 140. [ Lt; / RTI >

The backlight unit 160 includes a plurality of backlight (CCFL, LED) for generating light to be irradiated to the liquid crystal panel 140, and a backlight unit And an optical member (not shown) for improving the light efficiency. Here, the optical member includes a diffusion plate for uniformly irradiating light over the entire surface of the liquid crystal panel 140, a prism sheet for enhancing light efficiency by condensing the light emitted from the diffusion plate, and a polarizing sheet for polarizing the light .

The backlight driver 150 adjusts the brightness according to the magnitude of the supplied voltage or the amount of current. The backlight driver 150 converts the square wave signal into a triangle wave signal, And the driving power is supplied to the backlight. At this time, the backlight driver 150 controls the magnitude of the voltage supplied to the backlight, the amount of current, or the lighting time of the backlight by using the dimming signal.

That is, as the higher voltage or current is supplied, the backlight generates a higher luminance, and a lower luminance or lower luminance is generated as the lower voltage or the lower current amount is supplied. At this time, the amount of current is adjusted by using a pulse width modulation (PWM) method. Here, the duty means a time during which the backlight is turned on during one frame period, and the brightness of the backlight is higher as the lighting time becomes longer during one frame period of the backlight.

To this end, the backlight driver 150 generates a PWM signal for controlling the magnitude of the driving current and the voltage for turning on the backlight according to the dimming signal, and controls the lighting of the backlight using the duty value corresponding to the PWM signal.

Here, the backlight driving unit 150 may generate a dimming signal in accordance with a video signal input from the timing controller 110. When the user inputs the mode, the backlight driving unit 150 generates a dimming signal The driving of the backlight can be controlled.

The PWM signal is periodically repeated with the ON time at which a voltage greater than the reference voltage value is maintained and the OFF time at which the reference voltage value is maintained with a constant period T. The duty value is a ratio of the ON time to the OFF time. Accordingly, a driving current is supplied to the backlight to control the lighting of the backlight.

Further, the intensity of the driving current supplied to the backlight may be controlled by the duty value of the PWM signal to control the brightness of the backlight lighting. When the duty value is large, the brightness of the backlight is increased, and when the duty value is small, the brightness of the backlight can be decreased. For example, when the duty value according to the PWM signal is set to 100%, the backlight is controlled so that the brightness of the backlight is maximized, and when the duty value is set to 50%, the brightness of the backlight is set to the maximum brightness It is possible to control the lighting of the backlight to be 50%.

Here, the duty value of the PWM signal may be varied within a predetermined period T according to the luminance adjustment range of the predetermined backlight. When the user inputs the mode, the dimming signal supplied from the timing controller 110 . ≪ / RTI >

The liquid crystal display according to the embodiment of the present invention aligns the image signals R, G, and B input from the outside using the timing controller 110 and then inputs the mode from the user to the parameter generator 200 The driving of the backlight can be controlled by generating the range of the dimming signal of the backlight and the parameter of the dimming point according to the change of the gain of the video data.

Hereinafter, the parameter generator 200 and the timing controller 110 of the liquid crystal display according to the embodiment of the present invention will be described with reference to FIGS. 4 and 5. FIG.

A user who views an image can request a driving mode that can adjust the range of the gain and the dimming signal to request display quality suited to his or her taste or reduce power consumption.

In this case, the parameter generation unit 200 generates a parameter for the LCD panel 140 from the dimming signal range (the maximum dimming value, the minimum dimming value) for driving the backlight inputted from the user while preventing the gamma from being distorted. The gain of the backlight dimming signal and the video data signal corresponding to each gray of the image displayed on the liquid crystal display panel is automatically adjusted. The parameter generating unit 200 includes a dimming data generating unit 210, a gain value generating unit 220, a data converting unit 230, and a memory 240.

The dimming data generating unit 210 receives the maximum dimming value among the dimming signal ranges and transmits the previous maximum dimming value (Prev_Max_Dimming) preset in the memory 240 via the converting unit 230 Receive input. Thereafter, the maximum dimming value is compared with the previous maximum dimming value (Prev_Max_Dimming).

A new dimming signal range, i.e., a new maximum dimming value and a minimum dimming value, is calculated by calculating a ratio of the input maximum dimming value and the previous maximum dimming value (Prev_Max_Dimming).

Then, the previous dimming point (Prev_Dim_Point (n)) for each gray of the image stored in advance in the memory 240 is inputted via the data conversion unit 230. [ Then, a new dimming point (Dim_Point (n)) for each gray of the image displayed on the liquid crystal panel 140 is set based on the inputted previous dimming point.

The maximum dimming value generated by the dimming data generator 210 and the newly set dimming point are provided to the data converter 230 and the newly set dimming point is provided to the gain value generator 220.

The gain value generating unit 220 generates a weighted gain based on the dimming signal range input from the user. When the dimming signal range of the backlight is changed so that the backlight is driven to have a certain luminance range (for example, 20% to 70%), the gain of the image data must be changed so as to correspond to the luminance range of the backlight.

For this, the gain value generator 220 calculates the maximum value of the gain value for driving the backlight using the newly set dimming point from the dimming data generator 210 and the minimum dimming value input from the user, that is, the maximum gain Value (Max_Gain).

Here, the maximum gain value is generated when the dimming signal range is changed so that the backlight is driven to have a certain range of luminance (for example, 20% to 70%). Even if the luminance of the backlight is reduced, ), The gain value should be set based on the minimum luminance of the backlight, since the luminance of the image to be displayed should represent the original luminance. Therefore, a new maximum gain value is generated based on the minimum luminance of the backlight driven according to the minimum dimming value among the dimming signal ranges. Here, the maximum gain value can be set according to the number of bits of data. In case of 8 bits, the maximum gain value can be set to a value corresponding to 256 gradations. The maximum gain value generated by the gain value generation unit 220 is provided to the conversion unit 230.

At this time, the maximum gain value is obtained by comparing the dimming value of the original backlight and the dimming value for each newly set gradation from the higher gradation, and when the dimming value for each gradation becomes smaller than the minimum dimming signal value, the gain value of the gradation becomes the maximum gain value do.

The data converting unit 230 may be configured to store the maximum dimming value and the dimming point generated by the dimming data generating unit 210 and the maximum gain value generated by the gain value generating unit 220 in a memory 240 For example, data in the form of a decimal (Dec) is converted into data in a hexadecimal (Hex) form and provided to the memory 240.

In other words, a hexadecimal data stored in the memory 240, that is, a maximum dimming value generated and stored in the dimming data generator 210, a maximum gain value generated and stored in the dimming point and gain generator 220, And supplies the data to the dimming data generation unit 210 and the gain value generation unit 220. The dimming data generation unit 210 and the gain value generation unit 220 are the same as those shown in FIG.

Here, the memory 240 may be an EEPROM, and the range of the dimming signal stored in the memory 240, that is, the maximum dimming value, the dimming point, and the maximum gain value are provided to the timing controller 110.

The timing controller 110 arranges the image signals R, G and B inputted from the outside to be suitable for driving the liquid crystal panel 140 and outputs the aligned image data signals R ', B' and G ' And supplies it to the driving circuit unit 120 and the backlight driving unit 150.

Here, the image data may include individual gray-level values corresponding to pixel voltages to be applied to pixel electrodes of red, green, and blue pixels of the liquid crystal panel 140, and the image data signals R ', G ', B') may include a maximum dimming value and a dimming point provided from the memory 240, and a maximum gain value. At this time, the maximum dimming value and the dimming point may be supplied to the backlight driver 150 as PWM data.

The timing controller 110 generates a timing control signal for controlling the operation timing of the data driving circuit unit 120, the gate driving circuit unit 130 and the backlight driving unit 150 using the input timing synchronization signal TSS. Lt; / RTI >

Here, the timing synchronization signal TSS is a vertical synchronization signal Vsync; A horizontal synchronizing signal Hsync; A data enable signal (Data Enable); And a dot clock (DCLK).

The timing control signals are supplied to a data control signal DCS for supplying a data voltage to the data line DL of the liquid crystal panel 140 and a gate control signal GCS for driving the gate line GL of the liquid crystal panel 140. [ ). ≪ / RTI >

Here, the data control signal DCS may be a source start pulse, a source sampling clock, a source output enable signal, and a polarity control signal (Polarity). The gate control signal GCS may be a gate start pulse, a gate shift clock, a gate output enable signal, or the like.

The data driving circuit 120 converts the analog data voltages into positive / negative analog data voltages according to the image data signals R ', G', B 'including the new maximum gain value input from the timing controller 110, To the lines DL so that an image is displayed on the liquid crystal panel 140. [

The backlight driving unit 150 drives the backlight according to the video data signals R ', G', and B 'including the new maximum dimming value and the dimming point input from the timing controller 110. At this time, the backlight is driven to display the luminance corresponding to the new gain value of the image data.

In the above description, the parameter generator 200 is an internal component of the timing controller 110, but this is an example, and the parameter generator 200 can be configured independently.

The liquid crystal display according to an embodiment of the present invention including the above-described configuration can automatically control the variable range of the backlight according to the user's mode selection to control the dimming value of the backlight without limitation on the type, quantity and characteristics of the backlight have. Further, it is possible to provide a display quality suitable for the user's taste by controlling the gain of the image data and the dimming value of the backlight without changing the gamma which affects the display quality.

Further, the dimming signal of the backlight is automatically controlled in accordance with the gain change of the image data, and the backlight is driven so as to have low luminance while displaying the same luminance as the original luminance, thereby reducing power consumption.

Hereinafter, a driving method of a liquid crystal display device according to an embodiment of the present invention will be described with reference to FIG.

When a mode (dimming signal range change) is input from a user viewing an image displayed on the liquid crystal panel (S10), a new maximum dimming value and a dimming point are generated based on the maximum dimming value included in the dimming signal lane from the user (S20). At this time, the new maximum dimming value and the dimming point are generated by referring to the previous maximum dimming value stored in the memo (240) and the previous dimming point.

In step S30, a new maximum gain value is generated using the minimum dimming value included in the dimming signal lane from the user and the new dimming point generated in step S20.

Then, in step S40, the data of the decimal type is converted into the data of the hexadecimal type, as an example of a form in which the new maximum dimming value, the dimming point, and the maximum gain value can be stored in the memory.

Then, the parameters (data) of the new maximum dimming value, the dimming point and the maximum gain value are stored in the memory (S50).

The image data signals R ', G', and B 'are arranged to be suitable for driving the liquid crystal panel 140, and the image data signals R', G ', and B' And the backlight driving unit 150. [ The image data may include individual gray levels corresponding to pixel voltages to be applied to the pixel electrodes of the red, green, and blue pixels of the liquid crystal panel 140, A dimming value and a dimming point and a maximum gain value.

Thereafter, the backlight is driven using the image data signals R ', G', and B 'including the maximum dimming value and the dimming point to supply the changed luminance to the liquid crystal panel 140, And supplies image data signals R ', G', and B 'to the liquid crystal panel. Through this, the image is displayed by adjusting the transmittance of the light provided in the backlight (S60).

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

1 is a view showing a driving method of a liquid crystal display according to a conventional technique.

2 is a diagram showing a gain and dimming setting method of a liquid crystal display according to the related art.

3 is a view illustrating a liquid crystal display device according to an embodiment of the present invention.

4 is a diagram showing a parameter generation unit of a liquid crystal display device according to an embodiment of the present invention.

5 shows parameters stored in memory in accordance with a change in gain and dimming;

6 is a view showing a driving method of a liquid crystal display device according to an embodiment of the present invention.

Description of the Related Art [0002]

110: timing controller 120: data driving circuit

130: Gate driving circuit part 140:

142: TFT 150: backlight driver

160: backlight unit 200: parameter generating unit

210: dimming generator 220: gain generator

230: data conversion unit 240: memory

Claims (10)

A liquid crystal panel for controlling an optical transmittance of a liquid crystal according to an input image data signal to display an image; A backlight for supplying light to the liquid crystal panel; A backlight driver for driving the backlight; A timing controller for converting an input video signal into a video data signal in a frame unit and supplying the video data signal to the liquid crystal panel and the backlight driving unit; Receiving a dimming signal range including a maximum dimming value and a minimum dimming value, In response to a request from the user to change the dimming signal range for driving the backlight And a parameter generator for changing a gain value applied to the image data signal stored in the memory, the maximum dimming value, and the minimum dimming value. 2. The apparatus of claim 1, wherein the parameter generator Wherein the controller calculates a ratio of a maximum dimming value included in the dimming signal range to a previously stored previous maximum dimming value to generate a new maximum dimming value. 3. The apparatus of claim 2, wherein the parameter generator And generates a new dimming point (Dim_Point (n)) based on a previous dimming point (Prev_Dim_Point (n)) which means a specific gray (Gray) stored in the memory. 4. The apparatus of claim 3, wherein the parameter generator And generates a new gain value to be added to the image data signal using the minimum dimming value and the new dimming point. 5. The apparatus of claim 4, wherein the parameter generator And compares the dimming value of the original backlight with the dimming value of the newly set gradation from the higher gradation and sets the gain of the gradation to the maximum gain value when the dimming value of each gradation becomes smaller than the minimum dimming value. 6. The apparatus of claim 5, wherein the timing controller Supplying the image data signal to the liquid crystal panel, including the new gain value, And provides the image data with the new maximum gain value and a new dimming point to the backlight driver. 7. The apparatus of claim 6, wherein the backlight driver And uses the new maximum gain value and the new dimming point to drive the backlight to display a certain range of brightness. delete Receiving a dimming signal range including a maximum dimming value and a minimum dimming value step; Generating a new maximum dimming value and a new dimming point for driving the backlight based on a maximum dimming value included in the dimming signal range; Generating a new maximum gain value weighted to the image data using the minimum dimming value included in the dimming signal range and the new dimming point; Changing a previous maximum gain value and a previous maximum dimming value stored in the memory to the new maximum gain value and the new maximum dimming value; And And adding the new maximum dimming value, the new dimming point, and the new maximum gain value to the image data signal of the frame unit. 10. The method of claim 9, Driving a backlight to display a predetermined range of brightness using an image data signal including the maximum dimming value and a dimming point; And And driving the liquid crystal panel using an image data signal including the maximum gain value.

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