KR20130131162A - Luquid crystal display device and method for diriving thereof - Google Patents

Abstract

The present invention discloses a liquid crystal display device. More particularly, the present invention relates to a liquid crystal display device capable of reducing power consumption in a certain image through a driving frequency change and minimizing an observable increase of a flicker according to the frequency change, and to a method for driving the same. The liquid crystal display device according to an embodiment of the present invention comprises a liquid crystal panel, a data driver which supplies a data voltage to the liquid crystal panel, a timing controller which controls the operation timing of the data driver and includes a frequency setting unit which analyzes image data inputted by an external system and determines any one of a first driving frequency and a second driving frequency that is lower than the first driving frequency; and a setting information storage unit which stores setting information for generating a control signal of the data driver according to the first and second driving frequencies. The present invention sets image attribute information by an experiment value, analyzes the image provided from the external system and replays the video as well as the stopped image at a lower driving frequency than the conventional frequency in the section that is not beyond the range of flicker generation, thereby providing the liquid crystal display device capable of maintaining a high quality and reducing power consumption and the method for driving the same. [Reference numerals] (110) Gate driver;(120) Data driver;(130) timing controller;(140) setting information storage unit;(150) frequency setting unit

Description

Liquid crystal display and its driving method {LUQUID CRYSTAL DISPLAY DEVICE AND METHOD FOR DIRIVING THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and to a liquid crystal display device and a method of driving the same, which reduce power consumption in a specific image by switching a driving frequency and minimize an increase in visibility of flicker due to frequency switching.

Various portable devices such as mobile phones and laptop computers, and information electronic devices that realize high resolution and high quality images such as HDTVs, have been applied to flat panel display devices. The demand for) is increasing. As such flat panel display devices, a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), and an organic light emitting diode (OLED) have been actively studied. However, And realization of a large area screen, a liquid crystal display (LCD) is in the spotlight at present.

Referring to FIG. 1, a driving frequency is defined according to the number of images scattered on a screen per second. Referring to FIG. 1, a liquid crystal display having a driving frequency set to 60 Hz generates a new image of 60 frames per second. Will be displayed.

Therefore, when the driving frequency is lowered to 60 Hz or less, for example, 40 Hz, in order to reduce power consumption, images of fewer frames are displayed within the same time, thereby achieving the effect of power consumption. However, if the driving frequency of the liquid crystal display is lowered, the motion image shows little motion in the image quality in the case of the static image in which the object appearing on the screen is fixed. Image quality such as flicker or flickering of the screen may occur. Therefore, there is a limit in reducing power consumption as the driving frequency of the liquid crystal display is lowered.

In order to improve this, a method of analyzing a video received from an external system and operating at 60 Hz for a moving picture and a lower driving frequency for a still picture has been proposed. However, in the case of moving pictures, since the liquid crystal display device is set to 60 Hz as in the related art, there is a disadvantage in that the effect of reducing power consumption is not high.

In order to solve the above problems of the present invention, a liquid crystal display device and a driving method thereof which reduce power consumption by operating at a lower driving frequency than conventional ones according to the shape of the image while minimizing the deterioration in image quality as well as still images. The purpose is to provide.

In order to achieve the above object, a liquid crystal display device according to a preferred embodiment of the present invention, a liquid crystal panel; A data driver providing a data voltage to the liquid crystal panel; A timing setting unit configured to control an operation timing of the data driver and determine one of a first driving frequency and a second driving frequency that is higher than the first driving frequency by analyzing image data input from an external system; Controller; And a setting information storage unit for storing setting information for generating a control signal of the data driver according to the first and second driving frequencies.

The first and second driving frequencies are 40 Hz and 60 Hz, respectively.

The frequency setting unit may include a gray level determination unit configured to calculate a frequency according to the gray level value of the pixel included in the image data, and to determine which of the high frequency gray level values belongs to one of a sensing period and an undetected period; A pixel calculator which calculates the number of pixels included in the sensing period and compares the number of pixels with a minimum introduction number; And a density calculator for dividing each frame of the image data into a plurality of logical blocks and calculating a density of pixels included in the sensing period among the pixels on the block.

The sensing section may be 30 to 230 gradations out of 255 gradations.

The gray level determination unit may select the first driving frequency when the gray level value of the peninsula is included in the undetected period, and transmit image data to the pixel calculator when included in the detected period.

The minimized introduction water is characterized in that the range of 1000 ± 100 pieces.

The pixel calculator selects the first driving frequency when the number of pixels included in the sensing period is less than or equal to the minimum number of introductions, and transfers the image data to the calculated density calculation unit when the number of pixels exceeds the minimum number of introductions. do.

The denseness calculator may be configured to drive the second driving unit when the at least one block having a high density among pixels included in the sensing period exists or the number of pixels included in the non-sensing section has a greater number than a block having a high density among the plurality of blocks. A frequency is selected, and if the second frequency is not selected, the first driving frequency is selected.

The setting information storage unit is an EEPROM storing the setting information in the form of an LUT.

In order to achieve the above object, a driving method of a liquid crystal display device according to an embodiment of the present invention, receiving a timing signal and image data from an external system; Analyzing the image data to determine one of a first driving frequency and a second driving frequency that is higher than the first driving frequency; And generating a control signal corresponding to the determined driving frequency, and sorting and converting the image data.

The first and second driving frequencies are 40 Hz and 60 Hz, respectively.

The determining of any one of a first driving frequency and a second driving frequency higher than the first driving frequency by analyzing the image data may include calculating a frequency according to a gray value of a pixel included in the image data. Determining which of the high frequency gray level values belongs to one of a sensing section and an undetecting section; Calculating the number of pixels included in the sensing period and comparing the minimum number of introduced pixels; And dividing each frame of the image data into a plurality of logical blocks, and calculating a density of pixels included in the sensing period among the pixels on the block.

The sensing section may be 30 to 230 gradations out of 255 gradations.

The calculating of the frequency according to the gray value of the pixel included in the image data, and determining whether the high frequency gray value belongs to one of the sensing section and the non-sensing section, may not detect the gray scale value of the peninsula. If included in the interval, selecting the first driving frequency; And calculating the number of pixels included in the sensing period and comparing the number of pixels included in the sensing period with the minimum number of introductions.

The minimized introduction water is characterized in that less than 900 or more than 1100.

Computing the number of pixels included in the sensing period and comparing the minimum number of introductions may include: selecting the first driving frequency when the number of pixels included in the sensing period is less than or equal to the minimum number of introductions; And dividing each frame of the image data into a plurality of logical blocks when the number of pixels included in the detection period exceeds the minimum introduction number, and calculating the density of pixels included in the detection period among the pixels on the block. Characterized in that the steps to proceed.

Dividing each frame of the image data into a plurality of logical blocks, and calculating the density of the pixels included in the sensing section among the pixels on the block, the pixels included in the sensing section among the plurality of blocks include: Selecting the second driving frequency when at least one block having a high density exists or when there are more pixels in the undetected section than a block having a high density; And if the second driving frequency is not selected, selecting the first driving frequency.

Generating a control signal corresponding to the determined driving frequency, and aligning and converting the image data may include referring to the setting information stored in the setting information storage unit according to the determined driving frequency. .

According to an embodiment of the present invention, by setting the image attribute information according to the experimental value, and analyzes the image provided to the external system to reproduce not only the still image but also in the case of moving images in the drive frequency lower than the conventional range in the range that does not deviate from the flicker generation range As a result, it is possible to provide a liquid crystal display device and a driving method thereof having reduced power consumption while maintaining high image quality.

1 is a view showing an image display method of a 60Hz and 40Hz driving liquid crystal display device.
2 is a diagram illustrating the structure of a liquid crystal display according to an exemplary embodiment of the present invention.
3 is a graph illustrating flicker measurement values for gray levels of images for each driving frequency.
4A is a diagram illustrating an example of an image having different APL (Average Picture Level) values, and FIG. 4B is a diagram illustrating a method of calculating the density of pixels in consideration of APL.
5 is a diagram illustrating a structure of a timing controller according to an embodiment of the present invention.
FIG. 6A is a diagram illustrating an example of the frequency of each gray value in the image data, and FIG. 6B is a diagram illustrating an example of the image data of different pixel counts for each gray value.
7 is a diagram illustrating a method of driving a liquid crystal display according to an exemplary embodiment of the present invention.

Hereinafter, a liquid crystal display and a driving method thereof according to a preferred embodiment of the present invention will be described with reference to the drawings.

2 is a diagram illustrating the structure of a liquid crystal display according to an exemplary embodiment of the present invention.

As shown in the drawing, the liquid crystal display according to the present invention has a plurality of gate lines GL and data lines DL intersected and a pixel is defined at an intersection thereof, and a gate line GL. And a gate driver and a data driver 110 and 120 for driving the liquid crystal panel 100 through the data wiring DL, and receiving a timing signal and an image signal from an external system (not shown) to control the driver and the liquid crystal display device. It includes a timing controller 130 for determining the driving frequency of the configuration, and includes a setting information storage unit 140 for storing the setting information of the liquid crystal display device according to the driving frequency.

In the liquid crystal panel 100, a plurality of gate lines GL and a plurality of data lines DL are arranged in a matrix form in a direction perpendicular to the gate lines GL on the transparent substrate, and a plurality of pixels at intersections. The area is defined. A thin film transistor T is formed in each pixel area, and a liquid crystal cell CLC and a storage capacitor CST controlled by the thin film transistor are configured to display a screen.

The thin film transistor T is turned on when the scan signal from the gate line GL, that is, the gate high voltage is applied, and applies the data voltage from the data line DL to the liquid crystal cell CLC. In addition, the thin film transistor T is turned off when the gate low voltage is applied from the gate line GL to maintain the data voltage charged in the liquid crystal cell CLC for one frame.

The liquid crystal cell CLC represents a pixel electrode and a common electrode as a capacitor. The liquid crystal cell CLC includes a common electrode facing the liquid crystal and a pixel electrode connected to the thin film transistor T. The liquid crystal cell CLC is connected to the storage capacitor CST so that the charged data voltage is stably maintained until the next data voltage is charged. The pixel has a gray level by controlling the light transmittance of the liquid crystal cell CLC by changing the arrangement state of the liquid crystals according to the data voltage charged through the thin film transistor T.

In addition, a gate driver 110 including a plurality of shift registers is provided at one end of the liquid crystal panel 100 and electrically connected to the gate wiring GL formed on the liquid crystal panel 100 to sequentially gate each horizontal line. Output the drive signal.

The gate driver 110 turns on the thin film transistor T arranged on the liquid crystal panel 100 in response to the gate control signal GCS applied from the timing controller 130. The data voltage of the analog waveform supplied from the data driver 120 is applied to the liquid crystal cell CLC connected to each thin film transistor T.

As the gate control signal GCS, the gate control signal GCS includes a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable (GOE), and the like. . The gate start pulse GSP is a signal for controlling the first gate pulse to be applied to the shift register for generating the first gate pulse among the plurality of shift registers constituting the gate driver 110, (GSC) is a clock signal commonly input to all shift registers, and is a clock signal for shifting the gate start pulse (GSP). The gate output enable (GOE) controls the output of the shift registers to prevent turn-on of the thin film transistors overlapped with each other in the different horizontal sections.

The data driver 120 aligns the digital image signal RGB corresponding to the data control signals input from the timing controller 130, selects reference voltages, and converts them into analog data voltages. do. The data voltages are latched by one horizontal section 1H and are simultaneously input to the liquid crystal panel 100 through all the data lines DL.

The data control signal DCS includes a source start pulse SSP, a source shift clock SSC, a source output enable (SOE), and the like. . Here, the source start pulse SSP is a signal for controlling the data sampling start timing of the data driver 120, and the source sampling clock SSC is a driving IC constituting the data driver 120 in response to a rising or falling edge. Is a clock signal that controls the sampling timing of data. In addition, the source output enable SOE controls the output timing of the data driver 120.

The timing controller 130 receives the image data DATA applied from an external system (not shown) and timing signals such as a clock signal DCLK, a horizontal synchronization signal Hsync, and a vertical synchronization signal Vsync. A gate control signal GCS and a data control signal DCS are generated.

Here, the horizontal synchronization signal Hsync represents the time taken to display one line of the screen, and the vertical synchronization signal Vsync represents the time taken to display the screen of one frame. The clock signal DCLK is a signal for generating various signals in synchronization with the gate and data drivers 110 and 120 and the timing controller 130.

In addition, although not shown, the timing controller 130 is connected to an external system (not shown) through a predetermined interface so that the timing controller 130 can receive image-related signals and timing signals output from the external system at high speed without error. do. As such an interface, a low voltage differential signal (LVDS) method or a transistor-transistor logic (TTL) interface method can be used.

In particular, the timing controller 130 according to the embodiment of the present invention is further connected to the setting information storage unit 140 in which setting values related to the operation of the timing controller 130 according to frequency are stored. In addition, the timing controller 130 includes a frequency setting unit 150 that analyzes image data DATA received from an external system and determines a driving frequency of the liquid crystal display.

The setting information storage unit 140 looks up-table the setting information which is a reference for generating the gate control signal GCS and the data control signal DSC in response to the timing signal received by the timing controller 130. , LUT). The setting information storage unit 140 stores setting information on driving frequencies of at least one liquid crystal display, and after the timing controller 130 determines the driving frequency, the setting information storage unit 140 stores the setting information on the corresponding frequencies. The control signal is generated by referring to the setting information.

The setting information storage unit 140 may be implemented as a nonvolatile memory such as an electrically erasable and programmable read only memory (EEPROM).

The frequency setting unit 150 determines a driving frequency of the liquid crystal display by analyzing characteristics of the image data DATA received from an external system.

The image implemented by the liquid crystal display device has different characteristics of flicker depending on the driving frequency and the system. The frequency setting unit 150 selectively determines the driving frequency according to the gray level of the image, the number of pixels for each gray level, and the closeness of the pixels.

Hereinafter, a driving frequency setting method of the frequency setting unit will be described with reference to the accompanying drawings.

3 is a graph illustrating flicker measurement values for gray levels of images for each driving frequency.

Referring to FIG. 3, when the driving frequencies are 30 Hz, 40 Hz, 50 Hz, and 60 Hz in a liquid crystal display that implements 8-bit 255 gray scales, the flicker measurement values of the gray scales are compared. It can be seen that the measured value is high, and the flicker value is significantly lowered toward the higher frequency. In addition, the closer to the low grayscale (31 gray) for each drive frequency, the higher the flicker measurement value, and the closer to the high grayscale (255 gray), the lower the flicker measurement value. In 200 gray levels, there is almost no difference between driving frequencies as a saturation state, and flicker is also measured at a low value. Also, even if the 200 gray level or higher image is driven at 40 Hz lower than 60 Hz, the observer cannot recognize the flicker. Therefore, the high gray level image does not affect the image quality even when the driving frequency is reduced from 60 Hz to 40 Hz. Will not.

Table 1 below shows gray scales in which a plurality of observers recognize flicker for an image implemented at a low driving frequency of 40 Hz.

Low gradation High gradation A 17 200 B 16 210 C 25 207 D 20 217 E 18 220 Average 19 210

Table 1 shows that the observer evaluated the range of gray levels in which flicker is perceived. In the case of observer A, flicker is detected at 17 gray levels (17 gray) and 200 gray levels (200 gray) or less.

According to Table 1, it can be seen that flicker is visually recognized by an observer on an image of 19 to 19 (19 gray) or more to 210 to 210 (210 gray) on average in a 40 Hz driving liquid crystal display, and 19 to 19 (19 gray) or less. Since the flicker is not visually recognized when driving at 40 Hz for an image of more than 210 gray levels (210 gray), the driving frequency of the liquid crystal display may be set to 40 Hz.

That is, in a liquid crystal display device of 255 gray levels (255 gray), each pixel value is less than 19 gray levels (19 gray), and more than 210 gray levels (210 gray), the flicker undetection section for each gray level and other gray levels belong to the flicker detection section. It can be defined as.

Here, unlike the above-described flicker measurement value, the flicker is not visually recognized by the observer in the low gradation section (ex. 31 gradation) because it is not detected by the observer's eye due to the influence of the luminance component.

Therefore, the frequency setting unit 150 of the present invention first analyzes the input image data to determine whether the gray level of the image corresponds to the flicker detection section or the non-sensing section.

For example, the frequency of each gray level of each pixel may be obtained in one frame, and the flicker detection interval of the corresponding image may be determined by determining whether the gray level value having the most frequency belongs to the detection section or the non-detection section.

In the embodiment of the present invention, 30 gray scales (30 gray) or more and 230 gray scales (230 gray) or less are set as the non-flicker detection interval in consideration of the individual difference of the observer.

In addition, the frequency setting unit 150 calculates the number of pixels in one frame of the image corresponding to the sensing period and determines the degree of flicker viewing by comparing with the number of minimized introduction.

The above-described minimization introduction number serves as a reference for the number of pixels for which the flicker cannot be recognized when an observer views an image having a gray level included in the detection period. Although the gradation value for the pixel in one frame is included in the flicker detection section, if the number is small, the flicker is not actually seen by the observer. This is due to the viewing characteristics of the observer. Therefore, when the number of pixels in the sensing interval is less than the minimum number of introductions, the observer does not recognize the flicker even when driving at 40 Hz.

Therefore, the frequency setting unit 150 of the present invention does not generate flicker when the number of pixels in the inputted detection section is secondary analysis, that is, the number of pixels is calculated, and the image corresponding to the detection section is less than or equal to the minimum number of introductions in the detection section. Presumes not. In addition, flicker may occur if it is more than the minimum number of introductions. In the embodiment of the present invention, the minimum number of introductions is set within a range of 1000 ± 100 in consideration of individual differences of observers, but is not limited thereto.

In addition, the frequency setting unit 150 determines the driving frequency in consideration of the density of pixels, even if the image corresponds to the sensing period and more than the minimum number of introductions.

4A is a diagram illustrating an example of an image having different APL (Average Picture Level) values, and FIG. 4B is a diagram illustrating a method of calculating the density of pixels in consideration of APL.

Referring to FIG. 4A, APL refers to a value obtained by converting the luminance average of all the pixels on one frame as a ratio of the maximum luminance, and the APL is the 100% upper value (APL_H), the median value (APL_M), and the lower value. An example of an image having (APL_L) is shown.

The image having the upper value (APL_H) relates to a general web screen with a large number of full-white gradations, and the middle value (APL_M) and the lower value (APL_L) images each have many low gradation pixels or show very many images. will be. Therefore, in the present invention, calculation of the density of pixels based on an image of a web screen having a higher value APL_H, which is a general image, will be described.

FIG. 4B illustrates an example of a method of calculating the density of pixels, wherein one pixel is divided into a plurality of logical blocks, and for each block, one pixel having gray levels within a sensing interval and a gray level other than an undetected period is shown. After substituting 0 for pixels with 0, logical operations are performed to calculate the ratio of 1 value to 0 value for each block. As a result, it is determined that a block having a dominant value has a high density of gray levels corresponding to the detection interval.

If at least one block having a dominant density of gray levels exists, the corresponding image may be determined to have high flicker visibility. Here, the number of blocks in which one value prevails may be two or more.

Therefore, the frequency setting unit 150 according to the present invention determines the image having a block having a predominant value of 1, that is, a block having a high density as a third-order analysis, and when one or more blocks exist, the driving frequency for the image. It will be set to 40 Hz. Here, the density of 1 value compared to 0 value may vary according to the experimental value.

The frequency setting unit 150 of the present invention analyzes the image received through the above-described first to third order analysis, determines the driving frequency of the liquid crystal display device as 60 Hz or 40 Hz, and then refers to the setting information storage unit 140. By generating a control signal for driving to the frequency to provide to each driver (110, 120).

Meanwhile, as illustrated, the frequency setting unit 150 may be mounted inside the timing controller 130 or may be implemented as a separate circuit using a microcontroller unit (MCU).

Hereinafter, a structure of a timing controller of a liquid crystal display according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

5 is a diagram illustrating a structure of a timing controller according to an embodiment of the present invention.

As shown, the timing controller 130 of the present invention includes a data converter 132 for arranging and converting image data DATA, and a control signal generator for generating gate and data control signals GCS and DCS. 135 and a frequency setting unit 150 for analyzing a characteristic of the image data DATA to determine a driving frequency of the liquid crystal display.

The data converter 132 receives the image data DATA, sorts and converts the image data DATA, and outputs the converted image data DATA ′ to the data driver 120 of FIG. 2. The data driver consists of a shift register, a plurality of latches, a decoder, and a level shifter. Image data applied from an external system cannot be processed by the data driver. Therefore, the data converter 132 functions to sort and convert the data into a form that can be processed by the data driver.

Here, the data converter 132 sorts and converts the image data according to the setting value stored in the setting information storage unit 140 in response to the driving frequency determined by the frequency setting unit 150.

The control signal generator 135 controls the timing of operation of the gate driver and the data driver in response to timing signals such as the vertical and horizontal synchronization signals Vsync and Hsync and the clock signal DCLK input from an external system. Generate and output signals DCS and GCS.

Here, the above-described gate and data control signals DCS and GCS should be generated in correspondence with the set driving frequency. Therefore, the control signal generating unit 135 sets a setting value for the driving frequency determined by the frequency setting unit 150. The control signals DCS and GCS corresponding to 60 Hz or 40 Hz are generated by referring to the information storage 140.

The frequency setting unit 150 calculates a gray scale section determination unit 151 for determining a gray scale section for each frame of the input image data DATA, and a flicker generation minimization introduction number of the frame in which the gray scale section is determined as a flicker detection section. The pixel calculating unit 152 and the density calculating unit 153 for calculating the pixel density in the frame exceeding the minimum number of introductions to determine the driving frequency of the liquid crystal display.

The gray scale determination unit 151 uses the characteristic that the frequency flicker measurement value is high when the image is implemented at 40 Hz and the flicker measurement value is low when the image is implemented at 40 Hz. For each frame, it is determined whether the gray level value for all pixels is included in one of the flicker detection section and the non-sensing section, and when the frequency of the pixels included in the detection section is high, according to the analysis result of the pixel output unit 152. Determine the driving frequency. In addition, when the pixel included in the undetected section has a high frequency, the frequency determiner 150 determines the driving frequency as 40 Hz.

Referring to FIG. 6A, the flicker undetected section may be defined as less than 30 gray levels (30 gray) or less than 230 gray levels (230 gray), and a region having a high frequency of pixel gray values is included in the undetected section. An image with a graph characteristic of is implemented at 40Hz.

The pixel calculation unit 152 determines the driving frequency by using the minimum number of introductions, which are the number of pixels which cannot recognize the flicker. Even if the image having the characteristics included in the detection section by the gradation section determination unit 151 is estimated that the flicker is not visually recognized when the number of pixels is small, the number of pixels in the detection section is calculated to be less than the minimum number of introductions. The frequency determiner 150 determines the driving frequency as 40 Hz.

In addition, when the number of pixels in the sensing period is greater than or equal to the minimum introduction number, the frequency determiner 150 determines the driving frequency according to the analysis result of the density calculator 153. Here, the minimization introduction number may be defined as 1000 ± 100.

Referring to FIG. 6B, when the graph according to the pixel distribution of the image corresponds to the p1 region, that is, when the number of pixels in the detection interval is less than the minimum number of introductions, the driving frequency may be determined at 40 Hz, and according to the pixel distribution of the image. When the graph corresponds to the p2 region, the driving frequency may be determined at 60 Hz.

The density calculator 153 divides one screen into a plurality of logical blocks, and replaces each pixel having a gray level within the sensing period with one and a pixel having a gray level outside the non-sensing interval with 0 for each block. After that, each block is logically computed by substituting the substituted values between adjacent pixels, thereby calculating the density of 1 value compared to 0, and determining that there is a block in which 1 value is dominant or high in density, and the image is finally driven at 60 Hz. Determine the frequency.

If not, that is, if there is no block in which the pixel corresponding to the gray scale value in the sensing period is dominant or small, the density is determined to be low and the driving frequency is determined at 40 Hz.

Here, the number of blocks with high density and low density of 1 value compared to 0 value may be adjusted according to the experimental value.

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

7 is a diagram illustrating a method of driving a liquid crystal display according to an exemplary embodiment of the present invention.

As shown, the driving method of the liquid crystal display according to the embodiment of the present invention, the control signal and image data receiving step (S200), the gray scale section determination step (S210), the number of pixels in the detection section (S220) and And a density calculation step (S230), and after performing any one of the 40 Hz control signal generation step (S240) and the 60 Hz control signal generation step (S250) according to the image analysis result, the image data alignment and conversion step (S260) and It includes an output step (S270).

In the control signal and image data receiving step S200, the timing controller receives timing signals such as a clock signal DCLK, a horizontal synchronization signal Hsync, a vertical synchronization signal Vsync, and the image data DATA from an external system. Step.

In the step of determining the gray scale section (S210), the gray scale section discriminating unit of the frequency setting unit obtains the gray scale values for all the pixels for the image, calculates the frequency, and the high frequency gray scale values belong to any one of the flicker detection section and the non-sensing section. It is a step of determining whether or not.

When the frequency of the pixels included in the detection interval is high, the driving frequency is determined according to the analysis result of the pixel calculator, and the operation S220 is performed. In addition, when the frequency of the pixels included in the undetected section is high, the driving frequency is determined to be 40 Hz, and step S240 is performed.

In the pixel calculating step S220 of the sensing section, when the frequency of the pixels included in the sensing section is determined to be a high image, the number of pixels in the sensing section is calculated to determine the driving frequency as 40 Hz when the number of pixels is less than the minimum number of introductions. Proceed to step S240. In addition, when the number of pixels in the sensing period exceeds the minimum number of introductions, the driving frequency is determined according to the analysis result of the density calculator, and the operation S230 is performed. Here, the minimization introduction number may be defined as 1000 ± 100.

In the density calculating step (S230), when it is determined that the number of pixels in the sensing period exceeds the minimum number of introductions, the screen is divided into a plurality of logical blocks, and each block has a gray level in the sensing period. The density of pixels and pixels having gray levels other than the non-sensing section are calculated. In addition, when one or more blocks having a high density of pixels having gray levels in the detection period are determined to be high, the flicker visibility is determined to be high, and the driving frequency is determined to be 60 Hz. If not, that is, if there is no block in which the pixel corresponding to the gray scale value in the detection interval is dominant or small, it is determined that the density is low and the driving frequency is determined to be 40 Hz.

The 40Hz control signal generation step (S240) and the 60Hz control signal generation step (S260) are based on the driving frequency determined according to the above-described steps S210 to S230, and the gate driver and data with reference to the setting values stored in the setting information storage unit in the LUT method. In this step, the control signal of the driver is generated.

The image data sorting and converting step (S270) is a step of sorting and converting the image data received by the data converter in a form that can be processed by the data driver according to the driving frequency.

The output step S280 is a step of outputting the aligned and converted image data to the data driver according to a driving frequency of 40 Hz or 60 Hz. Accordingly, the data driver receives the image data from the timing controller, converts the image data into an analog data voltage, and provides the image data to the liquid crystal panel. The liquid crystal panel displays a gray level of an image corresponding to the data voltage, and the driving frequency thereof is determined by the frequency setting unit of the timing controller.

Accordingly, the present invention can minimize power consumption by driving at 40 Hz within a range where no flicker occurs in response to the image data.

Many details are set forth in the foregoing description but should be construed as illustrative of preferred embodiments rather than to limit the scope of the invention. Therefore, the invention should not be construed as limited to the embodiments described, but should be determined by equivalents to the appended claims and the claims.

100: liquid crystal panel 110: gate driver
120: Data driver 130: Timing controller
140: setting information storage unit 150: frequency setting unit

Claims (18)

A liquid crystal panel;
A data driver providing a data voltage to the liquid crystal panel;
A timing setting unit configured to control an operation timing of the data driver and determine one of a first driving frequency and a second driving frequency higher than the first driving frequency by analyzing image data input from an external system; Controller; And
A setting information storage unit storing setting information for generating a control signal of the data driver according to the first and second driving frequencies;
And the liquid crystal display device. The method of claim 1,
The first and second driving frequency is,
A driving method of a liquid crystal display device, characterized in that 40Hz and 60Hz respectively. The method of claim 1,
The frequency setting unit,
A gradation section determination unit for calculating a frequency according to the gradation value of the pixel included in the image data, and determining whether the gradation value of the high frequency belongs to one of a sensing section and a non-sensing section;
A pixel calculator which calculates the number of pixels included in the sensing period and compares the number of pixels with a minimum introduction number; And
A density calculation unit for dividing each frame of the image data into a plurality of logical blocks, and calculating the density of pixels included in the sensing period among the pixels on the block.
Liquid crystal display comprising a. The method of claim 3, wherein
The sensing period is a liquid crystal display, characterized in that more than 30 to 230 of the 255 gray scale. The method of claim 3, wherein
The gradation section discriminating unit,
And selecting the first driving frequency when the gray level value of the peninsula is included in the non-sensing section, and transferring the image data to the pixel calculator if included in the sensing section. The method of claim 3, wherein
The minimized introduction water is a liquid crystal display, characterized in that in the range of 1000 ± 100 pieces. The method of claim 3, wherein
The pixel calculation unit,
And selecting the first driving frequency when the number of pixels included in the sensing period is less than or equal to the minimized introduction number, and transferring the image data to the calculating density unit that exceeds the minimization introduction number. The method of claim 3, wherein
The density calculation unit,
Selecting the second driving frequency when at least one block having a high density among pixels included in the sensing period exists or the number of pixels included in the non-sensing section has a larger number than a block having a high density among the plurality of blocks, And when the second frequency is not selected, selects the first driving frequency. The method of claim 1,
And the setting information storage unit is an EEPROM storing the setting information in the form of an LUT. Receiving timing signals and image data from an external system;
Analyzing the image data to determine one of a first driving frequency and a second driving frequency that is higher than the first driving frequency; And
Generating a control signal corresponding to the determined driving frequency and arranging and converting the image data;
And a driving method of the liquid crystal display device. 11. The method of claim 10,
The first and second driving frequency is,
A driving method of a liquid crystal display device, characterized in that 40Hz and 60Hz respectively. 11. The method of claim 10,
Determining any one of a first driving frequency and a second driving frequency higher than the first driving frequency by analyzing the image data,
Calculating a frequency according to the gray value of the pixel included in the image data, and determining whether the high frequency gray value belongs to one of a sensing period and an undetected period;
Calculating the number of pixels included in the sensing period and comparing the minimum number of introduced pixels; And
Dividing each frame of the image data into a plurality of logical blocks, and calculating the density of pixels included in the sensing period among the pixels on the block;
Among them, at least one driving method of the liquid crystal display device. 13. The method of claim 12,
The sensing period is a driving method of the liquid crystal display device, characterized in that more than 30 to 230 of the 255 gray scale. 13. The method of claim 12,
The calculating of the frequency according to the gray value of the pixel included in the image data, and determining whether the high frequency gray value belongs to one of the sensing section and the non-sensing section,
Selecting the first driving frequency when the gray level value of the peninsula is included in the undetected section; And
Calculating the number of pixels included in the sensing period and comparing it with the minimum number of introductions when the gray level value of the peninsula is included in the sensing period.
Method of driving a liquid crystal display, characterized in that to proceed. 13. The method of claim 12,
The method of minimizing introduction number of liquid crystal display device, characterized in that 900 or more within 1100. 13. The method of claim 12,
Computing the number of pixels included in the detection period and comparing with the minimum number of introduction,
Selecting the first driving frequency when the number of pixels included in the sensing period is less than or equal to the minimum introduction number; And
When the number of pixels included in the detection period exceeds the minimum number of introductions, each frame of the image data is divided into a plurality of logical blocks, and the density of pixels included in the detection period among the pixels on the block is calculated. step
Method of driving a liquid crystal display, characterized in that to proceed. 13. The method of claim 12,
Dividing each frame of the image data into a plurality of logical blocks, and calculating the density of the pixels included in the sensing period among the pixels on the block,
Selecting the second driving frequency when at least one block having high density is included in the sensing period among the plurality of blocks, or when there are more pixels in the non-sensing period than a block having high density; And
If the second driving frequency is not selected, selecting the first driving frequency
Method of driving a liquid crystal display, characterized in that to proceed. 11. The method of claim 10,
Generating a control signal corresponding to the determined driving frequency, and sorting and converting the image data,
And referring to the setting information stored in the setting information storage unit, according to the determined driving frequency.

Images