KR101595444B1 - Driving apparatus for liquid crystal display device and method for driving the same - Google Patents

Abstract

The present invention relates to a driving apparatus for a liquid crystal display device and a driving method thereof, which can improve the process yield of LEDs and reduce the manufacturing cost of a backlight unit by compensating the problem of dispersion of color coordinates of LEDs used in backlight units on data A liquid crystal panel formed with a plurality of pixel regions; A gate and a data driver for driving a plurality of gates and data lines provided in the liquid crystal panel; A memory unit for storing and outputting compensation data corresponding to the LED information of the backlight inputted from the user; The image data input from the outside is converted according to the compensation data from the memory unit to generate converted image data and supplies the converted image data to the data driver and the gate and data control signal together with the dimming control signal, A timing controller for controlling the timing controller; And a backlight unit provided with the backlight and configured to emit light to the liquid crystal panel in accordance with the dimming control signal.

White LED, white LED scatter, backlight unit, liquid crystal display,

Description

Technical Field [0001] The present invention relates to a driving apparatus for a liquid crystal display,

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device capable of improving the process yield of LEDs and reducing the manufacturing cost of a backlight unit by compensating the problem of dispersion of color coordinates of LEDs used in backlight units on data To a driving apparatus and a driving method thereof.

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

The liquid crystal display device displays a desired image by controlling the amount of light transmitted from a backlight unit through a liquid crystal panel having a plurality of liquid crystal cells arranged in a matrix form.

In recent years, fluorescent lamps have been mainly used as a light source of a backlight unit. Recently, however, a backlight unit has been becoming more compact, thinner, and lighter in weight. Instead of a fluorescent lamp, a light emitting diode (LED), which is advantageous in terms of power consumption, A backlight unit using a diode is used.

As described above, when the LEDs are used as a light source in the backlight unit, white LEDs are mainly used. However, since the white LEDs have low process yield, the cost of the backlight unit increases.

Specifically, the white LEDs used in the backlight unit emit white light by molding yellow phosphors on a blue LED chip. Therefore, due to the difference in the main wavelength of the blue LED chip and the difference in the content of the yellow phosphor, white LEDs have a wider dispersion for white light even for high-brightness LEDs that realize the same white light.

Conventionally, in order to prevent the white reproducibility and luminance uniformity degradation caused by the problem of dispersion of the color coordinates of the white light, the full color coordinates of the white LEDs were inspected. However, when the white LEDs are discriminated by performing the chromaticity coordinate total inspection, many LEDs which fail to meet the reference value can not be used as a failure judgment, so that the yield of white LEDs is lowered and the manufacturing cost of the backlight unit is increased.

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 capable of improving the process yield of LEDs and reducing the manufacturing cost of the backlight unit by compensating the problem of dispersion of the color coordinates of LEDs used in the backlight unit on data, An object of the present invention is to provide a driving apparatus for a device and a driving method thereof.

According to an aspect of the present invention, there is provided an apparatus for driving a liquid crystal display, including: a liquid crystal panel including a plurality of pixel regions; A gate and a data driver for driving a plurality of gates and data lines provided in the liquid crystal panel; A memory unit for storing and outputting compensation data corresponding to the LED information of the backlight inputted from the user; The image data input from the outside is converted according to the compensation data from the memory unit to generate converted image data and supplies the converted image data to the data driver and the gate and data control signal together with the dimming control signal, A timing controller for controlling the timing controller; And a backlight unit provided with the backlight and configured to emit light to the liquid crystal panel in accordance with the dimming control signal.

Wherein the memory unit stores respective LED information corresponding to the degree of scattering of the white LEDs used in the backlight and the compensation data corresponding to each of the LED information, And supplies red, green, and blue compensation data corresponding to the inputted LED information to the timing controller.

Wherein the timing controller comprises: an image data sorting unit for sorting the image data by using at least one of synchronous signals from outside to be suitable for driving the liquid crystal panel; An image data compensator for compensating for the compensation data supplied from the memory unit to generate the converted image data and supplying the converted image data to the data driver, And a control signal generator for generating the gate control signal and the dimming control signal, and supplying the data, the gate driver, and the backlight unit, respectively.

Wherein the image data compensator adds or subtracts the compensation value of the compensation data to the gray level value of each of the sub pixels of the aligned image data input in every horizontal period unit, And sequentially supplies the converted image data to the data driver in every horizontal period unit.

The backlight unit includes a backlight including the plurality of white LEDs for generating light and an optical unit for improving the efficiency of light incident from the plurality of white LEDs, and a backlight unit for amplifying a pulse width modulation signal according to a dimming control signal from the timing controller And a backlight control unit for generating an AC driving signal for driving the plurality of white LEDs according to the generated pulse width modulation signal to control the white LEDs of the backlight.

According to another aspect of the present invention, there is provided a method of driving a liquid crystal display including a liquid crystal panel including a plurality of pixel regions, a gate for driving the liquid crystal panel, a data driver, and a timing controller A method of driving a liquid crystal display comprising the steps of: storing and outputting compensation data corresponding to LED information of a backlight inputted from a user using at least one memory unit; A step of generating converted image data by converting image data inputted from outside according to the compensation data and supplying the generated data to the data driver and controlling the gate and the data driver by generating a gate and a data control signal together with a dimming control signal ; And irradiating the liquid crystal panel with light according to the dimming control signal using the backlight.

Wherein the step of storing and outputting the compensation data comprises the steps of storing respective LED information corresponding to the degree of dispersion of the white LEDs used in the backlight and the compensation data corresponding to each LED information, And outputting compensation data of red, green and blue corresponding to the inputted LED information when any one of the LED information is inputted.

Wherein the step of generating the converted image data, the gate, the data and the dimming control signal comprises the steps of: arranging the image data to be suitable for driving the liquid crystal panel using at least one of synchronization signals from outside; Converting the gradation value of the image data arranged from the memory unit according to the compensation data supplied from the memory unit to generate the converted image data and supplying the converted image data to the data driver, And generating the data control signal, the gate control signal, and the dimming control signal, and supplying the data, the gate driver, and the backlight unit, respectively.

Wherein the step of generating the converted image data comprises the step of adding or multiplying the compensation value of the compensation data to the gray level value of each of the sub pixels of the aligned image data input in every horizontal period unit, And a step of sequentially supplying the converted image data to the data driver in units of horizontal periods.

Wherein the step of irradiating light to the liquid crystal panel includes the steps of irradiating the liquid crystal panel with light by providing the plurality of white LEDs for generating light and an optical unit for improving efficiency of light incident from the plurality of white LEDs, And controlling the white LEDs of the backlight by generating an AC drive signal for driving the plurality of white LEDs in accordance with the generated pulse width modulation signal .

The apparatus and method for driving a liquid crystal display according to an embodiment of the present invention can improve the process yield of LEDs by compensating the problem of dispersion of color coordinates of LEDs used in the backlight unit on data, The manufacturing cost of the apparatus can be reduced.

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

1 is a block diagram showing a driving apparatus of a liquid crystal display according to an embodiment of the present invention.

The liquid crystal display device shown in FIG. 1 includes a liquid crystal panel 2 formed with a plurality of pixel regions; A data driver 4 for driving a plurality of data lines DL1 to DLm; A gate driver 6 for driving the plurality of gate lines GL1 to GLn; A memory unit 10 for storing and outputting compensation data M_RGB corresponding to the LED information (Offset) of the backlight inputted from the user; Converts the image data RGB inputted from outside according to the compensation data M_RGB from the memory unit 10 to generate converted image data Data and supplies the converted image data Data to the data driver 4, A timing controller 8 for generating a control signal Dim and gate and data control signals GCS and DCS to control the gate and data drivers 4 and 6; And a backlight unit 12 including the above backlight and irradiating light to the liquid crystal panel 2 according to the dimming control signal Dim.

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

The data driver 4 receives a data control signal DCS from the timing controller 8, for example, a source start pulse SSP, a source shift clock SSC, a source output enable SOE (Source Output Enable) signal from the timing controller 8 into an analog voltage, that is, a video signal. Specifically, the data driver 4 compensates and gamma-transforms the input image data Data through the timing controller 8 in accordance with the SSC, latches the converted image data Data, and outputs the converted image data Data to the gate lines GL1 to GLn in response to the SOE signal. A video signal for one horizontal line is supplied to each data line DL1 to DLm for every one horizontal period in which a scan pulse is supplied. At this time, the data driver 4 selects a positive or negative gamma voltage having a predetermined level according to the grayscale value of the compensated image data Data, and supplies the selected gamma voltage to each of the data lines DL1 to DLm .

The gate driver 6 outputs a gate control signal GCS from the timing controller 8, for example, a gate start pulse GSP, a gate shift clock GSC, a gate output enable Sequentially generates a scan pulse in response to a Gate Output Enable (GOE) signal, and sequentially supplies the scan pulse to the gate lines GL1 to GLn. In other words, the gate driver 6 shifts the GSP from the timing controller 8 according to the GSC to sequentially supply a scan pulse, for example, a gate-on voltage to the gate lines GL1 to GLn. Then, the gate-off voltage is supplied during the period when the gate-on voltage is not supplied to the gate lines GL1 to GLn. Here, the gate driver 6 controls the pulse width of the scan pulse in accordance with the GOE signal.

The memory unit 10 stores LED offsets corresponding to the degree of scattering of white LEDs constituting the backlight 14 and compensation data M_RGB corresponding to each LED information Offset. Then, when any one of the LED information (Offset) selected from the user is inputted, the compensation controller supplies the red, green and blue compensation data M_RGB corresponding to the inputted LED information Offset to the timing controller 8. The memory unit 10 may be composed of at least one look-up table or the like, and any area of a memory provided in a timing board or the like may be used.

The timing controller 8 arranges the image data RGB input from the outside to be suitable for driving the liquid crystal panel 2 and outputs the gradation value of the aligned image data to the compensation data M_RGB inputted from the memory 10, Thereby generating converted image data Data in which the gray level values are converted. Then, the generated converted image data (Data) is supplied to the data driver (4).

The timing controller 8 also controls the gate and data control using at least one of a synchronizing signal input from the outside, that is, a dot clock DCLK, a data enable signal DE and horizontal and vertical synchronizing signals Hsync and Vsync. And controls the gate and data drivers 6 and 4 by generating signals GCS and DCS and supplying them to the gate and data drivers 6 and 4, respectively. The timing controller 8 generates a dimming control signal Dim by using at least one of the synchronizing signals according to the converted image data Data in which the gray level value is converted and supplies the dimming control signal Dim to the backlight unit 12 Thereby controlling the backlight unit 12. The timing controller 8 and the above-described memory structure and driving methods thereof will be described in more detail with reference to the accompanying drawings.

The backlight unit 12 includes a backlight 14 having a plurality of white LEDs for generating light in the liquid crystal panel 2 and an optical unit for improving the efficiency of light incident from the plurality of white LEDs, Generates a pulse width modulation (PWM) signal in accordance with a dimming control signal (Dim) from the dimming control signal (Dim), generates an AC driving signal ADS for driving the plurality of white LEDs And a backlight control unit 16 for controlling the white LEDs of the backlight.

The backlight 14 generates light by simultaneously or sequentially turning on / off the plurality of white LEDs according to the AC driving signal ADS. In addition, the optical unit diffuses and condenses the incident light from the light source to improve the light efficiency.

Here, the white LEDs of the backlight 14 are composed of a blue LED chip generating light, a yellow phosphor, and a lens covering them, and realize white light through a blue LED chip and a phosphor. Specifically, a plurality of white LEDs are made of YAG (Yttrium Aluminum Garnet), TAG (Terbium Aluminum Garnet), silicate, or the like, which are emitted by blue light and blue light emitted by a blue LED chip And yellow light emitted from the yellow phosphor are combined to emit white light.

Therefore, due to the difference in the main wavelength of the blue LED chip and the difference in the content of the yellow phosphor in the manufacturing process of white LEDs, white LEDs, as in the CIE color coordinates in FIG. 2, The spread of light is wide. Accordingly, in the present invention, LED offsets are determined so as to correspond to the degree of scattering of the white LEDs of the backlight 14 formed in each liquid crystal display device.

For example, as shown by the CIE color coordinates in FIG. 2, when the scattering degree of the white LEDs used in a backlight 14 corresponds to a reference value, the signal at the P0 level is set as the LED information (Offset) . If white LEDs whose scattering degree is less than the reference value by one level are used in any other backlight 14, the P-1 level signal is set as the LED information (Offset). In addition, when white LEDs having a scattering degree exceeding the reference value by more than two stages are used in any other backlight 14, the signal at the level P2 is set as the LED information (Offset). As described above, according to the present invention, the respective LED information (Offset) corresponding to the degree of scattering of the white LEDs used in each backlight 14 is set, and the set LED information (Offset) is stored in the memory unit 10 It is input in advance.

The backlight control unit 16 provided in the backlight unit 12 generates the PWM signal so as to correspond to the duty ratio of the dimming control signal Dim input from the timing controller 8. [ The backlight control unit 16 is driven in a burst mode in which the white LEDs are turned on / off by supplying or blocking the AC driving signal ADS to the backlight 14 according to the generated PWM signal. Here, the PWM signal is a signal in which the on / off period of the ramp, for example, the high / low period is varied according to the duty ratio information of the dimming control signal Dim.

3 is a block diagram specifically showing the memory unit and the timing controller shown in FIG. 4 is a diagram illustrating LED information stored in the memory unit of FIG. 3 and corresponding compensation data.

As shown in FIG. 4, the memory unit 10 shown in FIG. 3 stores red, green, and blue compensation data M_RGB corresponding to the LED offsets set by the user. Here, the compensation data M_RGB of red, green, and blue may be a value that is added to or subtracted from the image data RGB (i.e., red, green, and blue).

For example, when the red, green, and blue values to be multiplied by the red, green, and blue tone values are set to the compensation data (M_RGB), the compensation value corresponding to the LED information (Offset) 1 < / RTI > The red compensation value M_R corresponding to the LED information Offset input to the P1 signal may be 0.9, the green compensation value M_G may be 0.9, and the blue compensation value M_B may be 1. [ Also, the red compensation value M_R corresponding to the LED information Offset input to the P-2 signal may be 0.9, the green compensation value M_G may be 0.8, and the blue compensation value M_B may be 0.9.

The timing controller 8 shown in FIG. 3 uses the at least one of the synchronization signals DCLK, DE, Hsync, and Vsync from the outside to image data RGB to be suitable for driving the liquid crystal panel 2 The image data rearranging unit 24 rearranges the gray level values of the image data C_RGB aligned from the image data rearranging unit according to the compensation data M_RGB from the memory unit 10 to obtain the converted image data Data And supplies the data control signal DCS and the gate control signal GCS to the data driver 22 using at least one of the synchronization signals DCLK, DE, Hsync and Vsync. And a control signal generator 26 for generating a dimming control signal Dim and then supplying the data and gate drivers 4 and 6 and the backlight unit 12, respectively.

The image data sorting unit 24 receives at least one of the synchronizing signals DCLK, Hsync, Vsync, and DE together with the image data RGB from the outside. The input image data RGB are arranged in accordance with the size and resolution of the liquid crystal panel 2 using at least one of the supplied synchronization signals DCLK, Hsync, Vsync and DE. Then, the image data compensator 22 sequentially supplies the aligned image data C_RGB to the image data compensator 22 in units of horizontal periods.

The image data compensating unit 22 compensates the tone value of the image data C_RGB aligned from the image data arranging unit 24 according to the compensation data M_RGB from the memory unit 10 and outputs the converted image data Data, And supplies it to the data driver 4. Specifically, the image data compensation unit 22 adds or subtracts the compensation value of the compensation data M_RGB to the gray-level values of the respective sub-pixels of the aligned image data C_RGB inputted every horizontal period unit , And converts the tone value of each sub-pixel of the aligned image data (C_RGB). The converted image data (Data) thus generated is sequentially supplied to the data driver 4 in units of horizontal periods.

The control signal generator 26 includes a data control signal generator (not shown) and generates at least one of the synchronization signals DCLK, DE, Hsync, and Vsync input from the outside to generate SSP, SSC, and POL signals . Then, the generated SSP, SSC, and POL signals are supplied to the data driver 4. The data control signal DCS is a signal for controlling the driving timing of the data driver 4, and the POL signal is a signal for converting the polarity of a video signal supplied to each data line DL1 to DLm.

The control signal generator 26 includes a gate control signal generator (not shown) and generates a GSP, GSC, and GOE signals using at least one of the input synchronization signals DCLK, DE, Hsync, and Vsync . Then, the generated GSP, GSC, and GOE signals are supplied to the gate driver 6. The gate control signal GCS is a signal for controlling the driving timing of the gate driver 6.

In addition, the control signal generator 26 includes a dimming control signal generator (not shown) and receives at least one of the input synchronizing signals DCLK, DE, Hsync, and Vsync and the control signal from the image data compensator 22 And generates the dimming control signal Dim using the converted video data Data. The dimming control signal Dim is a signal for controlling the driving timings of the white LEDs provided in the backlight 14 and is controlled by the average or maximum gradation value of the converted image data Data corresponding to at least one frame The duty ratio is converted. In this way, the driving timing of the white LEDs can be changed by at least one frame unit by the dimming control signal Dim in which the duty ratio is converted. For this, the control signal generator 26 separately receives or shares the converted image data Data from the image data compensator 22.

As described above, the driving apparatus and the driving method of the liquid crystal display according to the embodiment of the present invention are supplied with LED offsets corresponding to the distribution of the color coordinates of the white LEDs used in the respective backlight units. Then, the image data RGB input from the outside is converted using the compensation data M_RGB corresponding to the supplied LED information (Offset).

As described above, the present invention can improve the utilization rate of LEDs by compensating for the problems caused by dispersion of the color coordinates of white LEDs on the image data. Therefore, the LEDs are not wasted, so that the process yield of the LEDs can be improved, which may reduce the manufacturing cost of the backlight unit.

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

1 is a block diagram showing a driving apparatus of a liquid crystal display according to an embodiment of the present invention;

FIG. 2 is a CIE chromaticity diagram showing scattering of luminance characteristics of LEDs emitting white light. FIG.

3 is a block diagram specifically showing the memory unit and the timing controller shown in Fig.

4 is a diagram illustrating LED information and corresponding compensation data stored in the memory unit of FIG.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

2: liquid crystal panel 4: data driver

6: Gate driver 8: Timing controller

10: memory unit 12: backlight unit

14: backlight 16: backlight control unit

22: Image data compensating unit 24: Image data arranging unit

26: Control signal generation unit

Claims (10)

A liquid crystal panel formed with a plurality of pixel regions; A gate and a data driver for driving a plurality of gates and data lines provided in the liquid crystal panel; A memory unit for storing and outputting red, green and blue compensation data corresponding to the LED information of the backlight inputted from the user; And supplies the converted data to the data driver. In addition, the data driver supplies the data driver with the gate and data control signals together with the dimming control signal, A timing controller for controlling the gate and the data driver; And And a backlight unit provided with the backlight and configured to emit light to the liquid crystal panel according to the dimming control signal, The memory unit Storing the red LED, the green LED, and the blue LED corresponding to each LED information corresponding to the degree of dispersion of the color coordinates of the white LEDs used in the backlight, And supplies the red, green, and blue compensation data corresponding to the inputted LED information to the timing controller when any one of the LED information selected from the user is inputted. delete The method according to claim 1, The timing controller An image data sorting unit for sorting the image data to be suitable for driving the liquid crystal panel using at least one of synchronizing signals from outside, An image data compensator for compensating the gray level value of the image data arranged from the image data arrangement unit according to the compensation data supplied from the memory unit to generate the converted image data and supplying the generated converted image data to the data driver, And a control signal generator for generating the data control signal, the gate control signal and the dimming control signal using at least one of the synchronization signals, and supplying the data control signal, the gate control signal and the dimming control signal to the data and gate driver and the backlight unit, respectively And a driving circuit for driving the liquid crystal display device. The method of claim 3, The image data compensation unit The gradation value for each sub-pixel of the aligned image data is converted by adding or multiplying the compensation value of the compensation data to the gradation value for each sub-pixel of the aligned image data input in every horizontal period unit, And sequentially supplies the image data to the data driver in units of horizontal periods. The method of claim 3, The backlight unit The backlight including the plurality of white LEDs generating light and the optical portion improving the efficiency of light incident from the plurality of white LEDs, and Generates a pulse width modulation signal in accordance with a dimming control signal from the timing controller and generates an AC driving signal for driving the plurality of white LEDs according to the generated pulse width modulation signal to control white LEDs of the backlight And a backlight control unit for driving the liquid crystal display device. A driving method of a liquid crystal display device including a liquid crystal panel formed with a plurality of pixel regions, a gate for driving the liquid crystal panel, a data driver, and a timing controller, Storing and outputting red, green and blue compensation data corresponding to the LED information of the backlight inputted from the user using at least one memory unit; And generates the converted image data and supplies the converted image data to the data driver and generates a gate and a data control signal together with the dimming control signal, Controlling a gate and a data driver; And And irradiating the liquid crystal panel with light in accordance with the dimming control signal using the backlight, The step of storing and outputting the compensation data Storing the red LED, the green LED, and the blue LED corresponding to the respective LED information corresponding to the degree of dispersion of the color coordinates of the white LEDs used in the backlight, and And outputting red, green, and blue compensation data corresponding to the inputted LED information when any one of the selected LED information is input from the user. delete The method according to claim 6, The step of generating the converted image data, the gate, the data, and the dimming control signal Arranging the image data to be suitable for driving the liquid crystal panel using at least one of synchronizing signals from outside, Converting the gradation value of the image data arranged from the image data arrangement unit according to the compensation data supplied from the memory unit to generate the converted image data and supplying the converted image data to the data driver, And generating the data control signal, the gate control signal, and the dimming control signal using at least one of the synchronization signals, and supplying the data control signal, the gate control signal, and the dimming control signal to the data and gate driver and the backlight unit, respectively A method of driving a liquid crystal display device. 9. The method of claim 8, The transformed image data generation step Converting the gray level value of each sub-pixel of the aligned image data by adding or multiplying the compensation value of the compensation data to the gray level value of each sub-pixel of the aligned image data input in every horizontal period unit, and And sequentially supplying the converted image data to the data driver in every horizontal period unit. 9. The method of claim 8, The step of irradiating light to the liquid crystal panel A step of irradiating light to the liquid crystal panel with the plurality of white LEDs generating light and the optical unit improving the efficiency of light incident from the plurality of white LEDs; Generating a pulse width modulation signal in accordance with the dimming control signal and generating an AC drive signal for driving the plurality of white LEDs according to the generated pulse width modulation signal to control the white LEDs of the backlight And a driving method of the liquid crystal display device.

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