KR20080063435A - Display device and driving method thereof - Google Patents

Abstract

A display device and a driving method thereof are provided to clearly display moving pictures by suppressing a motion blurring displayed on a liquid crystal panel. A display device includes a hold type display panel(10), a data driver(14), a frame converter, and an edge adaptive grayscale compensator(22). The data driver drives data lines of the display panel in response to video data. The frame converter converts the video data of a first frame frequency supplied to the data driver to the video data of a second frame frequency. The second frame frequency is higher than the first frame frequency. The edge adaptive grayscale compensator alternates the video data to be supplied to a driver between low and high grayscale levels for every second frame periods. The edge adaptive grayscale compensator alternatively performs the high grayscale and low grayscale compensation processes according to an edge of a frame grayscale of the video data of the first frame frequency.

Description

Display device and driving method thereof

In order to better understand the drawings used in the detailed description of the invention, a brief description of each drawing is provided.

1A and 1C are diagrams for explaining a pixel data conversion state in a conventional impulse method.

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

3A and 3C are diagrams showing correction characteristics of pixel data in an embodiment of the present invention.

4 is a detailed block diagram of the edge adaptive over driver shown in FIG.

FIG. 5 is a detailed block diagram of the edge adaptive selection controller shown in FIG. 2.

`` Explanation of symbols for main parts of drawings ''

10 liquid crystal panel 12 gate driver

14: data driver 16: timing control unit

18 frame conversion unit 20 polarity control unit

22: Gradation Compensator 24: Edge Adaptive Overdriver

26: edge adaptive selection control 30,32: frame memory

40: high gradation compensator 42: low gradation compensator

44: mixer 50,64: frame delay

52A: High Weight Compensator 52B: Low Weight Compensator

54: selector 56: sub frame delay

58,68 EX-NOR Gate 60: Average Gradient Detector

62: latch 66: comparator

SW1 to SW3: first to third control switches

The present invention relates to a liquid crystal display, an electroluminescent-type display, or a pixel driven by a switching element using amorphous silicon, polycrystalline silicon, or the like for each pixel. The present invention relates to a display device including a light emitting element such as a light emitting diode (LED), and more particularly to a display device for performing gradation processing of a video signal.

A display device for maintaining light emitted from each of a plurality of pixels at a desired amount within a predetermined period (for example, a period of length corresponding to one frame period) based on image data input for each frame period. Liquid crystal display devices are becoming popular. In an active matrix liquid crystal display device, a switching element (eg, a thin film transistor) that supplies a pixel electrode and a video signal to each of a plurality of pixels arranged in a two-dimensional or matrix shape. ) Is installed. The video signal is supplied to the pixel electrode through the switching element, for example, from one of a plurality of data lines (called video signal lines) extending in the vertical direction of the screen. The switching elements are arranged at predetermined intervals (for example, 1) from one of a plurality of gate lines (called scan signal lines) extending across the plurality of data lines (for example, in the horizontal direction of the screen). Each frame period) receives a scan signal and supplies a video signal to one of the plurality of data lines to the pixel electrode. Therefore, the switching element maintains the pixel electrode at a potential based on the " video signal supplied thereto according to the previous scan signal " until the next scanning signal is received, and maintains the pixel provided with this pixel electrode at the desired brightness. do.

This operation is in contrast to the impulse emission operation of a cathode-ray tube, which is represented by a braun tube that emits a phosphor installed at each pixel at the moment of receiving an image signal. With respect to this impulse light emission, the image display operation of the liquid crystal display device of the same active matrix system described above is often referred to as hold-type emission. In addition, image display such as an active matrix liquid crystal display device is also employed in a display device of an electroluminescence type (called EL type) or a light emitting diode array type, and the operation thereof controls voltage control of the pixel electrode described above. The description will be made by substituting the carrier injection amount control to the electroluminescent element or the light emitting diode.

A display device using such hold light emission displays an image by holding the brightness of each pixel within a predetermined period, and thus displays the image displayed according to, for example, another image in the successive pair of the frame periods. When replacing with, the pixel does not respond sufficiently. This phenomenon corresponds to a pixel set to a predetermined brightness in a certain frame period (e.g., the first frame period) even in the next frame period (e.g., the second frame period) following this frame period. It is explained from maintaining the brightness according to the previous frame period (the first frame period) until it is set to one brightness. In addition, this phenomenon is characterized in that a part of the video signal (or a corresponding amount of charge) sent to the pixel in any of the above-described frame periods (first frame period) is changed in the following frame period (second frame period). It is also explained from the so-called hysteresis of the video signal in each pixel, which interferes with the video signal (or the amount of electric charge accordingly) to be sent to the pixel. When a moving image is displayed by a display device (for example, a liquid crystal display) using hold type light emission, so-called blurring in which the outline of an object becomes unclear as compared to a cathode ray tube which emits pixels impulsely. Blurring Phenomenon is caused.

In order to solve this blurring, a method of driving an image of 60 frames as shown in FIG. 1A into an image of 120 subframes (that is, each subframe to two subframes) as shown in FIG. 1B or 1C is used. have. As shown in FIG. 1, a method of driving two subframes, as shown in FIG. 1, performs high gamma compensation on low-compensation subframes including low-compensation pixel data having low gamma compensation of pixel data of a 60-frame image and pixel data of a 60-frame image. High compensation subframes containing one pixel data are alternately recorded on the liquid crystal panel. FIG. 1B illustrates a method in which subframe image data is recorded on the liquid crystal panel in a form in which a high compensation subframe is arranged after the low compensation subframe L. FIG. FIG. 1C illustrates a method in which subframe image data is recorded on the liquid crystal panel in a form in which a low compensation subframe is arranged after the high compensation subframe H. FIG.

However, in the manner in which the pixel data of the low compensation subframe is recorded in the liquid crystal panel before the pixel data of the high compensation subframe every frame period, the liquid crystal cell cannot sufficiently respond to the pixel data of the elevated gradation level. Similarly, even in the manner in which the pixel data of the high compensation subframe is recorded in the liquid crystal panel before the pixel data of the low compensation subframe every frame period, the liquid crystal cell cannot sufficiently respond to the pixel data of the lowered gradation level. Since the liquid crystal cell on the liquid crystal panel cannot thus sufficiently respond at the falling edge or rising edge of the sub-frame image data, not only a sufficient pseudo impulse effect can be obtained but also motion blurring phenomenon is still present in the image displayed on the liquid crystal panel. Can be caused. As a result, not only the moving images are difficult to be clearly displayed but also noise such as flicker is generated.

Accordingly, it is an object of the present invention to provide a display device and a driving method thereof capable of obtaining a sufficient impulse driving effect.

Another object of the present invention is to provide a display device suitable for displaying a moving picture clearly and a driving method thereof.

According to one or more exemplary embodiments, a display device includes a hold type display panel; A driver for driving a data line of the display panel in response to video data; A frame converter which converts video data of a first frame frequency to be supplied to the data driver into video data of a second frame frequency higher than a first frame frequency; And low gray level and high gray level correction of the video data to be supplied from the frame converter to the driving unit every second frame period, wherein the low gray level and high gray level are changed according to an edge of the frame gray level of the video data of the first frame frequency. And an edge adaptive gradation correction section for causing the gradation correction to be changed.

The display device further includes an over driver that weight-compensates the gradual compensated video data to be supplied from the edge adaptive gradation correction unit to the driving unit based on a difference from the previous one.

The over driver compensates the grayscale corrected video data from the edge adaptive grayscale correction unit with a different weight based on an edge state of the frame grayscale of the video data of the first frame frequency supplied to the frame converter. can do.

The over driver will compensate for the grayscale corrected video data with a high weight when the edge direction of the frame grayscale of the video data of the first frame frequency is changed.

According to an embodiment of the present disclosure, a method of driving a display device includes converting video data of a first frame frequency to be supplied to a driving unit of a hold type display panel into video data of a second frame frequency higher than the first frame frequency. Doing; And low and high gray level correction of the video data to be supplied from the frame converter to the driving unit alternately every second frame period, wherein the low gray level is determined according to an edge of the frame gray level of the video data of the first frame frequency. Causing the correction of the high gradation to be changed.

The driving method of the display device may further include weighting compensation of the grayscale compensated video data to be supplied to the driving unit based on a difference from the previous one.

The weighting compensating step will compensate the grayscale compensated video data with different weights based on the edge state of the frame grayscale of the video data of the first frame frequency.

In addition to the objects of the present invention as described above, other objects, other advantages and other features of the present invention will become apparent from the detailed description of the preferred embodiment with reference to the accompanying drawings.

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

2 is a block diagram schematically illustrating a liquid crystal display according to an exemplary embodiment of the present invention. Referring to FIG. 2, the liquid crystal display device includes a gate driver 12 connected to a plurality of gate lines GL1 to GLn on the liquid crystal panel 10 and a plurality of data lines DL1 to DLm on the liquid crystal panel 10. The data driver 14 connected is provided. The plurality of gate lines GL1 to GLn and the plurality of data lines DL1 to DLm are formed on the liquid crystal panel 10 to cross each other so that the plurality of pixel regions are distinguished. Each pixel area of the plurality of pixel regions switches a pixel driving signal to be supplied to a corresponding liquid crystal cell (not shown) from a corresponding data line DL in response to a scan signal on a corresponding gate line GL (not shown). Not formed). The liquid crystal cell adjusts the amount of light passing through the pixel region according to the voltage level of the pixel driving signal to enable an image to be displayed. As a result, a pixel including one thin film transistor and one liquid crystal cell is formed in each of the pixel regions.

The gate driver 12 enables the plurality of gate lines GL1 to GLn sequentially by a predetermined period (for example, one sub horizontal synchronization signal) for each sub-frame period. To this end, the gate driver 12 generates a plurality of scan signals having exclusively a gate enable pulse shifted sequentially in the period of the sub horizontal synchronization signal. The gate enable pulses included in each of the plurality of scan signals have the same width.

Whenever one of the plurality of gate lines GL1 to GLn is enabled, the data driver 14 receives one pixel pixel driving signal corresponding to the number of data lines DL1 to DLm (that is, one gate). Pixel driving signals corresponding to the number of pixels arranged in a line. Each pixel driving signal corresponding to one line is supplied to a corresponding pixel (ie, a liquid crystal cell) on the liquid crystal panel 10 via a corresponding data line DL. In this case, each of the pixels arranged on the gate line GL passes an amount of light corresponding to the voltage level of the pixel driving signal. In order to generate one line of pixel driving signals, the data driver 14 sequentially inputs one line of pixel data for each period of the enable pulse included in the scan signal, and sequentially inputs one line of pixels of pixels. Simultaneously convert the data into an analog pixel drive signal. The data driver 14 generates a pixel driving signal of a voltage (or current) corresponding to the gray value of the pixel data whenever the plurality of gate lines GL1 to GLn are sequentially and exclusively enabled, on the data line DL. Supply. The data driver 14 causes one line of pixel driving signals to be applied to opposite data lines (for example, odd and even data lines) with opposite polarities to each other.

The liquid crystal display of FIG. 2 inputs a synchronization signal SYNC from an external video data source (for example, an image signal demodulator included in a graphic module or a television receiving module of a computer system) through a control transmission line CTL. And a frame converter 18 for inputting video data from an external video data source via a data transmission line DTL. The input video data input through the data transmission line DTL includes a pixel data stream sequentially arranged in units of frames. The frame frequency of the input video data corresponds to the number of images displayed on the liquid crystal panel 10 in one second and is usually set in the range of 30 to 120 Hz. For convenience of description, it is assumed in the embodiment of the present invention that the frame frequency of the input video data is 60 Hz.

The frame converter 18 converts video data of a frame frequency of 60 Hz from the data transmission line DTL into video data of a sub frame frequency of 120 Hz. To this end, the frame converter 18 includes first and second frame memories 30 and 32 connected between the first and second control switches SW1 and SW2. The first control switch SW1 causes the video data from the data transmission line DTL to be alternately supplied to the first and second frame memories 30 and 32 on a frame basis.

For example, the first control switch SW1 transmits video data of the odd main frame from the data transmission line DTL to the first frame memory 30 in the odd frame period, while in the even-numbered frame period. The video data of the even-th frame from the data transmission line DTL is transferred toward the second frame memory 32. The second control switch SW2 is switched to the complementary state with the first control switch SW1 so that the first and second frame memories 30 and 32 alternate with each other during the frame period. To be connected to the control switch SW3. As a result, when the first frame memory 30 is connected to the data transmission line DTL in one frame period, the second frame memory 32 is connected to the third control switch SW3 of the gradation correction unit 22. do. On the contrary, when the first frame memory 30 is connected to the third control switch SW3 of the gray scale correction unit 22, the second frame memory 32 stores pixel data of one frame from the data transmission line DTL. Will be saved. Both the first and second frame memories 30 and 32 read two times the pixel data of one frame, which is stored in advance, at twice the speed for two frame periods connected to the third control switch SW3. Allow video data to be generated. The video data of the odd-numbered subframe read from each frame memory 30, 32 is inevitably the same as the video data of the even-numbered subframe. The video data of these odd subframes and the video data of even-numbered subframes correspond to the video data of one frame.

The gradation correction unit 22 causes gradation correction of the pixel data of the odd subframe and the pixel data of the even subframe by a predetermined level. For example, if the pixel data of the odd subframe is high gray-corrected, the pixel data of the even subframe is low gray-corrected. Conversely, if the pixel data of the odd-numbered sub-frame is low gray-corrected, the pixel data of the even-numbered sub-frame is high gray-corrected. To this end, the gradation correction unit 22 includes a high gradation compensator 40 and a low gradation compensator 42 connected in parallel between the third control switch SW3 and the mixer 44.

The third control switch SW3 is switched for each period of the sub vertical synchronization signal so that the pixel data (or video data) is alternately supplied to the high gradation corrector 34 and the low gradation corrector 36 by frame. Further, the third control switch SW3 changes the selection order of the high gradation corrector 34 and the low gradation corrector 36 within the frame period. The selection order of the third control switch SW3 is determined by the increase or decrease in the average gradation (i.e., luminance) of the pixel data for the frame. For example, when the average gradation value of the pixel data of one frame increases, the third control switch SW is applied to the high gradation compensator 40 in the frame period until the average gradation value of the consecutive frames decreases. First, the pixel data of the subframe is supplied, and then the pixel data of the subframe is supplied to the low gray level compensator 42. On the other hand, when the average gradation value of the pixel data for any one frame is lowered, the third control switch SW is first applied to the low gradation compensator 42 in the frame period until the average gradation value of successive frames is lowered. The pixel data of the subframe is supplied, and then the pixel data of the subframe is supplied to the high gray scale corrector 40. As a result of the switching operation of the third control switch SW3, the subframe stream output from the mixer 44 has a low gray level compensation subpixel after the pixel data of the first high gray level compensation subframe, as shown in FIG. 3B. The pixel data of the frame is output in the order in which the pixel data of the high gradation compensated subframe is positioned after the pixel data of the low gradation compensated subframe from the frame in which the average gradation value of the frame is lowered, and then the average The pixel data of the low gray level compensated subframe is positioned in the order of the pixel data of the high gray level compensated subframe again from the frame in which the gray level rises.

The high gradation corrector 40 increases the gradation value of the pixel data of the subframe from the third control switch SW3 by a predetermined level (for example, by 25 gradation levels). The pixel data of the high gradation-corrected subframe by the high gradation corrector 40 is supplied to the mixer 44. On the other hand, the low gradation corrector 42 lowers the gradation value of the pixel data of the sub-frame from the third control switch SW3 by a predetermined level (for example, by 25 gradation levels). The pixel data of the low gradation-corrected subframe by the low gradation corrector 42 is supplied to 44 alternately with the pixel data of the high gradation-corrected subframe output from the high gradation corrector 40.

Pixel data of the subframe in which the gradation value is upwardly corrected by the high gradation corrector 34 and pixel data of the subframe in which the gradation value is downwardly corrected by the low gradation corrector 36 are mixed in the mixer 38, and FIG. As described above, the low gray level compensated pixel data and the high gray level compensated pixel data are alternately arranged for each subframe. The low gray and high gray pixel data, which are alternated in units of sub-frames in the mixer 38, are converted into pixel driving signals in analog form one by one in the data driver 14 to correspond to one line of pixels on the liquid crystal panel 10. By being supplied to the field, the bright and dark images are displayed alternately, and the display order of the bright and dark images is reversed each time the average gradation of the frame is changed. Since the liquid crystal panel 10 is driven as described above, an impulse driving effect can be improved. Accordingly, the occurrence of the motion blur phenomenon displayed on the liquid crystal panel 10 can be suppressed, and the afterimage occurrence is reduced.

As described above, the arrangement order of the pixel data of the high gradation compensated subframe and the pixel data of the low gradation compensated subframe is reversed according to whether the average gradation of the frame pixel data rises or falls. The bright image and the dark image are displayed alternately on the liquid crystal panel, and the display order of the bright image and the dark image is reversed as the average gradation of the frame rises or falls. Since the liquid crystal panel 10 is driven as described above, an impulse driving effect can be improved. In addition, the occurrence of the motion blur phenomenon displayed on the liquid crystal panel 10 can be suppressed, and the afterimage is also reduced.

The timing controller 16 doubles the synchronization signals SYNC from the control transmission line CTL. Using the frequency multiplied synchronization signals, the timing controller 16 causes the gate driver 12 and the data driver 14 to be driven at a speed twice as fast as the frequency of the input synchronization signal. To this end, the timing controller 16 controls the gate control signals necessary for generating a plurality of scan signals for the gate driver 12 to scan the plurality of gate lines GL1 to GLn on the liquid crystal panel 10 every subframe. Generate (GCS). In addition, the timing controller 16 sequentially inputs one line of pixel data for each period in which the data driver 14 enables the gate line GL, and sequentially inputs one line of pixel data in analog form. It generates data control signals DCS necessary to convert and output the pixel driving signal. In addition, the timing controller 16 includes the first and the second. The first switch control signal FSC1 for switching the control switches SW1 and SW2 complementary to each frame period and the second switch control signal FSC2 for switching the third control switch SW3 to each subframe period. Will occur). Here, the second switch control signal FSC2 may be generated by dividing the sub-vertical synchronizing signal by a frequency of 1/2, and the sub-vertical synchronizing signal may be generated by doubling the frequency of the vertical synchronizing signal. In addition, the timing controller 16 may generate a memory control signal MCS for controlling the write operation of the first and second frame memories 30 and 32 and the read operation performed at twice the speed of the write operation. The second frame memories 30 and 32 are supplied to the second frame memories 30 and 32.

The polarity control unit 20 generates a polarity control signal POL to be supplied to the data driver 14 in response to the vertical and horizontal synchronization signals multiplied by twice the frequency from the timing control unit 16. The polarity control signal POL generated by the polarity control unit 20 inverts a logic state (high logic and low logic) for each period of two frequency multiplied horizontal synchronization signals and a waveform that is inverted each time a subframe is changed. Have In response to the polarity control signal POL, the data driver 14 causes the pixel driving signal applied to the data lines to have an inverted polarity every two gate lines and to have an inverted polarity every subframe period. do. Accordingly, the liquid crystal panel 10 may be driven to be polarity-inverted for each pixel on the horizontal side and polarity-inverted for one or two pixels on the vertical side. In addition, the pixels on the liquid crystal panel 10 are driven by pixel driving signals of inverted polarity for each subframe. In other words, the liquid crystal panel 10 may be driven by either a 1 dot-2 line-frame inversion method or a 1 dot-1 line-frame inversion method.

The liquid crystal display according to the exemplary embodiment may further include an edge adaptive over driver 24 connected between the gray scale compensator 22 and the data driver. The edge-adaptive over driver 24 compensates the gray value of the pixel data of the subframe from the gray scale corrector 22 with a weight according to the difference from the gray value of the previous frame, but the pixel data of the previous subframe and the current The pixel data is compensated with a high or low weight depending on whether all of the pixel data of the sub-frame is low gray or high gray compensated. For example, when the pixel data of the previous subframe and the current subframe is high and low gray compensated or low and high gray compensated, respectively, the edge adaptive over driver 24 lowers or increases the pixel data with a low weight. To compensate. On the contrary, when the pixel data of the previous subframe and the current subframe are both low gray compensated or high gray compensated, the edge adaptive over driver 24 lowers or high compensates the pixel data with a high weight. In other words, when the average gray level of the pixel data in the unit of frame input through the data transmission line DTL falls or rises at least two times in succession, the pixel data is compensated with a high weight when the first fall or rise occurs. On the other hand, the pixel data is compensated with a low weight in the subsequent rise or fall including the second. The high and low compensation of the pixel data depends on the gray level of the pixel data of the current frame being higher and lower than the pixel data of the previous frame. For example, when the pixel data of the current frame has a higher gradation level than the pixel data of the previous frame, the edge adaptive over driver 24 compensates the pixel data as much as the weight, while the pixel data of the current frame is the previous frame. In the case of having a gradation level lower than the pixel data of, the edge adaptive over driver 24 compensates the pixel data lower by a weight. The process of differential weight compensation by the edge-adaptive over driver 24 to be gradually lowered according to the continuous number of rising or falling edges of the frame average gray scale is clearly described through the sub-frame stream as shown in FIG. 3C.

The pixel data of the sub-frame, which are differentially weighted to be gradually lowered according to the continuous number of rising or falling edges of the frame average gray scale, in the form of a pixel driving signal via the data driver 14, the pixels on the liquid crystal panel 10. Is applied to the pixel, thereby improving the response speed of the pixel. Accordingly, the impulse driving effect of the liquid crystal panel 10 may be further improved. In addition, the occurrence of the motion blur phenomenon displayed on the liquid crystal panel 10 may be minimized, and the afterimage and flicker may be minimized. As a result, the moving image can be displayed clearly by the liquid crystal display according to the present invention.

The liquid crystal display of FIG. 2 includes an edge adaptive selection controller 26 responsive to pixel data in units of frames from the data transmission line DTL. The edge adaptive selection controller 26 calculates an average gray level value for each frame of the pixel data from the data transmission line DTL and compares the average gray level values of adjacent frames to detect edges at which the average gray level value rises or falls. In addition, the edge adaptive selection control unit 26 supplies a second switch control signal to be supplied to the third control switch SW3 and the edge adaptive over driver 24 from the timing control unit 16 whenever a rising or falling edge is detected. The phase of the FSC2 is inverted, and the phase inverted signal is supplied to the third control switch SW3 and the edge adaptive over driver 24 as the edge adaptive switch control signal EFSC. By the edge adaptation switch control signal EFSC, the arrangement order of the pixel data of the high gradation subframe and the low gradation subframe pixel data is reversed. Based on the edge adaptive switch control signal EFSC, the edge adaptive over driver 24 determines whether the pixel data of the previous subframe and the current subframe are both low gray level or high gray level corrected.

FIG. 4 is a detailed block diagram illustrating the edge adaptive over driver 24 of FIG. 2 in detail. Referring to FIG. 4, the edge adaptive over driver 24 includes a frame delayer 50, a high weight compensator 52A, and a low weight, which commonly input pixel data of a subframe from the mixer 44 of FIG. 2. Compensator 52B is provided. The frame delay unit 50 delays the pixel data of the subframe from the mixer 44 shown in FIG. 2 in the frame period (ie, two sub frame periods). The pixel data of the frame-delayed subframe by the frame retarder 50 is supplied to the high weight compensator 52A and the low weight compensator 52B.

If the pixel data of the frame-delayed subframe and the pixel data of the current subframe differ from each other by a predetermined level or more in the gradation level, the high weight compensator 52A performs the gradation level of the pixel data of the current subframe by the high weight according to the difference. Compensate to be higher or lower. For example, if the pixel data of the current subframe is at least a certain level higher than the pixel data of the frame-delayed subframe, the high weight compensator 52A adjusts the gradation level of the pixel data of the current subframe by a high weight corresponding to the difference. Raise. On the contrary, if the pixel data of the current subframe is lower than a predetermined level by the pixel data of the frame-delayed subframe, the high weight compensator 52A lowers the gradation level of the pixel data of the current subframe by a high weight corresponding to the difference. Let it go. In contrast, if the difference between the pixel data of the current subframe and the pixel data of the frame-delayed subframe is within a certain level, the high weight compensator 52A outputs the pixel data of the current subframe to the selector 54 as it is.

Similarly, if the pixel data of the frame-delayed subframe and the pixel data of the current subframe differ by more than a certain level from the gradation level, the low weight compensator 52B of the pixel data of the current subframe by the low weight according to the difference Compensate for the gradation level being raised or lowered. For example, if the pixel data of the current subframe is at least a certain level higher than the pixel data of the frame-delayed subframe, the low weight compensator 52B adjusts the gradation level of the pixel data of the current subframe by a low weight corresponding to the difference. Raise. On the contrary, if the pixel data of the current subframe is lower than a predetermined level by the pixel data of the frame-delayed subframe, the low weight compensator 52B lowers the gradation level of the pixel data of the current subframe by a high weight corresponding to the difference. Let it go. Alternatively, if the difference between the pixel data of the current subframe and the pixel data of the frame-delayed subframe is within a certain level, the low weight compensator 52B outputs the pixel data of the current subframe to the selector 54 as it is.

Edge adaptive over driver 24 of FIG. 4 includes subframe delay 56 and exclusive-responsive common to edge adaptive switch control signal EFSC from edge adaptive selection control 26 of FIG. A NOA (EX-NOR) gate 58 is provided. The sub frame delay unit 56 delays the edge adaptive switch control signal EFSC by one sub frame period (i.e., 1/2 frame period). This sub frame-delayed edge adaptive switch control signal is supplied to the EX-NOR gate 58. The EX-NOR gate 58 supplies a select control signal of a specific logic (e.g., high logic) to the selector if the edge adaptive switch control signal EFSC and the sub frame-delayed edge adaptive switch control signal are the same, If both signals are different from each other, the selection control signal of the basis logic (for example, low logic) is supplied to the selector 54.

The selection control signal of a specific logic is generated during one subframe period when the pixel data of adjacent subframes are all low gray or high gray corrected. This is due to the edge adaptive switch control signal maintaining a certain logic or basis logic during the even-numbered sub-frame period of the previous frame and the odd-numbered sub-frame period of the current frame when the gray level average value between the frames first falls or rises.

The selector 54 converts the pixel data of the subframe from the high weight compensator 52A and the pixel data of the subframe from the low weight compensator 52B into a logical state of the selection control signal from the EX-NOR gate 58. Therefore, it is selectively supplied to the data driver 14 of FIG. For example, if the selection control signal has a particular logic (i.e., when the frame average gray level first falls or rises), the selector 54 may retrieve the pixel data of the high weight compensated subframe from the high weight compensator 52A. It supplies to the data driver 14 of FIG. Conversely, if the selection control signal maintains the underlying logic (i.e., if the frame average gradation falls or rises two or more times in succession), then the selector 54 performs a low weight compensated subframe from the low weight compensator 52B. Pixel data is supplied to the data driver 14 of FIG. The pixel data of the subframe output from the selector 54 is compensated with a high weight at the first falling or rising of the frame average gray scale (or average luminance), as shown in FIG. Subsequent rises or falls, including the second, are compensated with low weights.

FIG. 5 is a detailed block diagram illustrating in detail the edge adaptive selection controller 26 of FIG. 2. The edge adaptive selection control unit 26 of FIG. 5 includes an average gradation detector 60, a latch 62, a frame delay unit 64, a comparator 66 and an EX connected to the data transmission line DTL of FIG. A NOR gate 68; In response to the vertical synchronization signal Vsync, the average gradation detector 60 integrates the pixel data for the frame data inputted in the vertical scanning period after being initialized in the vertical retrace period, that is, the frame average luminance value (that is, the frame average luminance value). ) Is calculated. To calculate this average gradation value, the average gradation detector 60 responds to the data clock DCLK. The data clock DCLK and the vertical synchronization signal Vsync may be supplied to the average gray scale detector 60 from the timing controller 16 of FIG. 2 or an external video source.

The latch 62 latches the frame average gradation value from the average gradation detector 60 for each frame period in response to the vertical synchronization signal Vsync. The frame average gradation value is latched at the time of the vertical blanking period. The latch 62 supplies the latched frame average gray value to the frame delay 64 and the comparator 66.

The frame delay unit 64 delays the frame average gray value from the latch 62 by one frame period. The frame-delayed frame average gradation value is supplied to comparator 66.

The comparator 66 compares the current frame average gray value from the latch 62 with the previous frame average gray value from the frame delay 64 to detect rising or falling frames. If the current frame average gradation value is greater than the previous frame average gradation value, comparator 66 generates a comparison signal of a particular logic (e.g., high logic) to indicate that the frame average gradation has risen. On the other hand, if the current frame average gradation value is smaller than the previous frame average gradation value, the comparator 66 generates a comparison signal of the base logic (eg, low logic) to indicate that the frame average gradation has fallen.

The EX-NOR gate 68 selectively inverts the phase of the second switch control signal FSC2 from the timing control unit 16 of FIG. 2 in accordance with the logic state of the comparison signal from the comparator 66, thereby providing an edge. Generate an adaptive switch control signal (EFSC). If the comparison signal maintains a certain logic, the edge adaptive switch control signal EFSC has the same phase as the second switch control signal FSC2. In this case, the gradation correction unit 22 outputs the pixel data in such a manner that the low gradation subframe is positioned after the high gradation subframe. Alternatively, if the comparison signal has a basis logic, the edge adaptive switch control signal EFSC has a phase opposite to the second switch control signal FSC2. In response to the edge adaptive switch control signal EFSC having a phase opposite to that of the second switch control signal FSC2, the gray scale correcting unit 22 of FIG. 2 arranges the pixel data in such a manner that a high gray subframe is disposed after the low gray subframe. Is output. In addition, the inverted subframe period of the phase of the edge adaptive switch control signal EFSC, the pixel data of the high weight compensated subframe is output from the edge adaptive over driver 24 of FIG. 2, and the period of the remaining subframes. The pixel data of the low weight compensated subframe is outputted to the.

As described above, in the liquid crystal display and the driving method thereof according to the present invention, the pixel data of the high gradation compensated subframe and the pixel data of the low gradation compensated subframe according to whether the average gradation of the frame pixel data increases or decreases. The arrangement order of is reversed and written on the liquid crystal panel. The bright and dark images are alternately displayed on the liquid crystal panel, but the display order of the bright and dark images is reversed as the average gradation of the frame rises or falls. Since the liquid crystal panel is driven in this way, the impulse driving effect can be improved. In addition, the occurrence of the motion blur phenomenon displayed on the liquid crystal panel can be suppressed, and the afterimage is also reduced. As a result, the liquid crystal display device and the driving method thereof according to the present invention can display a moving picture clearly.

Further, the pixel data of the differential weight compensated sub-frame is written on the liquid crystal panel to be gradually lowered according to the continuous number of rising or falling edges of the frame average gray scale, thereby improving the response speed of the pixel on the liquid crystal panel. Accordingly, the impulse driving effect of the liquid crystal panel 10 can be further improved, so that the occurrence of motion blur in the image displayed on the liquid crystal panel can be minimized. As a result, the occurrence of afterimages and flicker is further reduced. Furthermore, the moving image can be clearly displayed by the liquid crystal display and the driving method thereof according to the present invention.

As described above, the present invention has been described with reference to the embodiments shown in the drawings, which are merely exemplary, and a person of ordinary skill in the art without departing from the spirit and scope of the present invention. It will be apparent that various modifications, changes, and equivalent other embodiments are possible. Accordingly, the scope of the present invention to be protected should be defined by the appended claims.

Claims (11)

A hold type display panel; A data driver for driving a data line of the display panel in response to video data; A frame converter which converts video data of a first frame frequency to be supplied to the data driver into video data of a second frame frequency higher than a first frame frequency; And The low and high gray levels of the video data to be supplied from the frame converter to the driver are alternately corrected every second frame period, and the low and high gray levels are changed according to an edge of the frame gray level of the video data of the first frame frequency. And an edge-adaptive gradation correction unit for causing the correction of the to be changed. The method of claim 1, wherein the edge adaptive gray scale correction unit A high gradation compensator for increasing a gradation value of video data of a second frame frequency from the frame converter; A low gradation compensator for lowering a gradation value of video data of a second frame frequency from the frame converter; A mixer for mixing video data from the high and low gray level compensators to supply mixed video data to the data driver; A third switch selectively supplying video data of a second frame frequency from the frame converter to the high and low gray level compensators; And And an edge adaptation selection control unit for changing the switching order of the third switch based on the edge state of the frame gray level of the video data of the first frame frequency supplied to the frame conversion unit. The method of claim 2, The edge adaptive selection control unit causes the third switch to select a high gray scale corrector and then select the low gray scale corrector during the first frame period when the gray scale of the video data of the first frame frequency maintains a rising edge. Display device characterized in that. The method of claim 1, And an over-driver for weight-compensating the gradally compensated video data to be supplied to the data driver from the edge adaptive gradation correction unit based on a difference from the previous one. The method of claim 4, wherein The over driver compensates the grayscale corrected video data from the edge adaptive grayscale correction unit with a different weight based on an edge state of the frame grayscale of the video data of the first frame frequency supplied to the frame converter. Display device characterized in that. The method of claim 5, wherein the over driver, And when the edge direction of the frame gray level of the video data of the first frame frequency is changed, compensating the gray level corrected video data with a high weight. The method of claim 1, wherein the frame converter First and second frame memories for changing the video data of the first frame frequency to a second frame frequency; A first switch configured to alternately input video data of the first frame frequency to the first and second frame memories; And And a second switch that is driven to complement the first switch and selects video data of second frame frequencies from the first and second frame memories and supplies the selected video data to the edge adaptive gray scale correction unit. Display device. The method of claim 1, And the display panel comprises a liquid crystal panel. Converting video data of a first frame frequency to be supplied to a driving unit of a hold type display panel into video data of a second frame frequency higher than the first frame frequency; And The low and high gray levels of the video data to be supplied from the frame converter to the driver are alternately corrected every second frame period, and the low and high gray levels are determined according to an edge of the frame gray level of the video data of the first frame frequency. And causing the correction of the gray level to be changed. The method of claim 9, And weighting-compensating the gradation-compensated video data to be supplied to the data driver based on a difference from the previous one. The method of claim 10, And the weighting compensating step comprises compensating the grayscale compensated video data with different weights based on an edge state of a frame grayscale of the video data of the first frame frequency.

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