KR20140006404A - Field sequential display method liquid crystal display apparatus - Google Patents

Abstract

Disclosed are a time division display method and a liquid crystal display device in the present invention. In the liquid crystal display device, the frame of an input image is converted into multiple sub-frames (f1, f2, f3 - fn) so that the image is displayed at a frequency higher than the frequency of the frame of the input image signal. The time division display method of the liquid crystal display device comprises: a step (Sa1) of generating multiple image signals having different brightness levels - the average brightness of the multiple image signals is substantially equal to the brightness of the input image signal - from the input image signal for each of pixels constituting the frame of the input image signal; a step (Sa2) of determining grayscales for respective sub-frames - the number of the generated image signals corresponds to the number of sub-frames - based on the grayscales of the generated multiple image signals for each pixel; a step (Sa3) of generating multiple sub-frames based on the determined grayscales of the sub-frames and the generated multiple image signals; and a step (Sa4) of displaying the generated sub-frames. The grayscales applied to the sub-frames are composed of a combination of three or less grayscales by including a substantive black grayscale (grayscale of zero or nearly zero), a substantive white grayscale (grayscale of 255 or nearly 255), and a variable medium grayscale (M). Therefore, at the time of the time division display, the lateral visibility can be improved while the front visibility is maintained at the same level. [Reference numerals] (210) Image signal generating unit; (220) Grayscale determining unit; (230) Sub-frame generating unit; (240) Display signal applying unit

Description

FIELD SEQUENTIAL DISPLAY METHOD LIQUID CRYSTAL DISPLAY APPARATUS [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time-division display method and a liquid crystal display device, and more particularly to a time-division display method and a liquid crystal display device capable of improving a side image quality of a VA (Vertical Alignment) mode.

Most of flat panel TV display products are adopting LCD technology, and high-definition TV LCD products adopt one of a horizontal electric field mode (IPS mode) and a vertical orientation mode (VA mode). In the IPS mode, the liquid crystal molecules have an initial orientation parallel to the substrate surface. The liquid crystal molecules in the horizontal orientation are rotated in the azimuth direction by the horizontal electric field generated by the electrodes formed on one substrate, and the optical axis of the liquid crystal layer rotates, Thereby controlling the polarization. On the other hand, the VA mode initially has a liquid crystal molecular orientation perpendicular to the substrate. This is because when a voltage is generated between the electrodes on both substrates, the liquid crystal rotates in a polar angle direction to induce the movement of the optical axis of the liquid crystal layer, .

Both IPS and VA modes have been developed as key technologies for high-quality LCD technology. Overcoming the narrow viewing angle problem of TN (Twisted Nematic) technology, which is mainly used in monitors and notebooks, I cry. However, the IPS technology has a wide viewing angle characteristic in principle, whereas the VA mode itself does not have a wide viewing angle characteristic. Therefore, all VA mode products adopt a multi-domain structure and optical compensation films. The adoption of multi-domain technology and optical compensation film technology has resulted in considerable improvement in viewing angle, but still has the problem of dimming of color on the side. For this reason, the VA mode mostly employs a pixel division technique in which one pixel is divided into two sub-pixels and a different voltage is applied to each pixel. The pixel segmentation technology is very helpful for improving the picture quality of the VA mode products.

The VA mode adopts the pixel segmentation technique to improve the side image quality. The pixel division technique has the problems that the number of signal transmission lines (bus-lines) increases, the number of TFTs increases, and the aperture ratio, which is an effective area of pixels, decreases because each pixel is divided into two sub-pixels and driven. This results in problems such as an increase in the manufacturing cost of the LCD and an increase in power consumption due to the reduction of the transmittance.

On the other hand, besides the mode technology, stereoscopic 3D technology is becoming an essential technology of TV products. Stereoscopic 3D technology is a technique designed to allow different image images to be recognized in the left and right eyes of viewers. Currently, commercialized stereoscopic 3D technology is implemented in two ways. First, the time is divided into four subframes for each frame, the first two frames display the left eye image, the second two frames display the right eye image, and the synchronized 3D shutter-glass (glasses) To be selectively recognized by a person. This is called time-sharing 3D technology or shutter glass method. The second stereoscopic 3D technique attaches a patterned optically anisotropic film to the screen so that the odd-numbered horizontal lines have left-handed circularly polarized light and the even-numbered horizontal lines have priority circularly polarized light. The viewer wore glasses with a polarizing plate, while the left glasses transmit only the left-handed polarized light and the right glasses transmit only the preferential polarized light. Therefore, the viewer recognizes only the odd-numbered horizontal lines in the left eye and the even-numbered horizontal lines in the right eye. This is referred to as space division 3D technology or FPR (film with patterned retardation). VA mode, which has fast response time of liquid crystal, mainly adopts time-sharing 3D technology, and IPS mode adopts space division 3D technology.

However, behind such advantages of the time division method, there are problems such as side visibility. There are various known techniques for improving the lateral visibility. However, these techniques are generally insufficient in the level of improvement of the side viewability, and are sensitive to changes in luminance depending on the temperature. In addition, gamma tuning is not easy and there is a problem that it conflicts with a high frame frequency technique for realizing motion picture driving. In addition, there is a problem of collision with the 3D technique of the time division method.

Korean Patent Laid-Open Publication No. 10-2007-0021978 ("Image Display Device, Electronic Device, Liquid Crystal TV, Liquid Crystal Monitor Device, Image Display Method, and Computer-Readable Recording Medium", Sharp Kabushiki Kaisha, published on February 23, 2007)

It is an object of the present invention to solve the above problems and provide a time division display method and a liquid crystal display device capable of improving a side picture quality of a VA mode without applying a pixel division technique.

Another object of the present invention is to provide a time-division display method and a liquid crystal display device for limiting a response speed of liquid crystal of a pixel constituting a panel in order to obtain similar side visibility or more side view visibility in comparison with an existing pixel division structure will be.

In order to achieve the above object, the present invention provides a time-divisional display method comprising: inputting a video frame to be displayed at a frequency higher than a frame frequency of an input video signal into a plurality of sub-frames f1, f2, f3, A plurality of image signals having different luminance from an input image signal for each pixel of the pixels constituting the input frame, the method comprising the steps of: (Sa1) generating an average of the luminance of the input video signal substantially equal to the luminance of the input video signal; A step Sa2 of determining gradations for each subframe based on the gradation of a plurality of image signals of each pixel generated, wherein the number of generated image signals corresponds to the number of subframes; Generating (Sa3) a plurality of subframes based on the determined gray level of the subframe and the generated plurality of video signals; And a step (Sa4) of displaying the generated sub-frame, wherein the gradation applied to the sub-frame includes a substantial black gradation (gradation close to 0 or 0), a substantial white gradation (gradation close to 255 or 255) And may be composed of combinations of three or less gradations including a variable intermediate gradation (M).

The order of gradation of the subframe may be a dark gradation to a bright gradation order, a bright gradation to a dark gradation order, or a sequence of repeating the above two orders.

The gradation determination step Sa2 may include determining the intermediate gradation M by measuring an average luminance appearing while changing the gradation of the subframe.

The gradation determination step Sa2 may include determining a normalized gradation value corresponding to a gradation value of a plurality of image signals of each pixel of the subframe as the gradation of the subframe.

The sub frame is divided into four regions (a low gray level region, a relay gray level region, a high gray level region, a highest gray level region, and a high gray level region) according to a gray level of a plurality of video signals of each pixel, Area).

The sub-frame generating step Sa3 includes the steps of: (a) setting a low gradation region (0 to 255,0,0,0) and a low gradation region (a, b, c, d) A sub-frame b, a sub-frame c, a sub-frame c, and a sub-frame d, wherein 0 to 255 are implemented as sub-frames corresponding to the corresponding sub- 0 means a gray scale value of 0 or a gray scale value close to 0, 255 means a gray scale value of 255 or a gray scale value close to 255 -, and a relay adjustment region 255,0 to 255,0,0 , High gradation areas (255, 255, 0 to 255, 0) and highest gradation areas (255, 255, 255, 0 to 255); 255, 0, 255, 0, 255), the highest gradation region (255, 255, 255, 0 to 255) ; (c) The gradation range (0 to 255, 0, 0, 0), the used gradation range (255, 0 to 255, 0 to 255, 0) and the highest gradation range (255, 255, 255, 0 to 255) How to implement; 0 to 255, 0 to 255, 0 to 255, 0 to 255, 0 to 255, 0 to 255, and 0 to 255 in the high gradation range (d) ); And (e) a method of implementing on all subframes (0 to 255, 0 to 255, 0 to 255, 0 to 255) for the entire gradation region; And generating the subframe by selecting at least one of the subframes.

The time division display method may further include applying a fast frame algorithm to the input frame before the image signal generation step Sa1, wherein the fast frame algorithm application step includes interpolating based on a continuous input frame interpolation) into four high-speed sub-frames; Calculating a signal variation amount between the high-speed sub-frames; And a step of performing a frame algorithm if the change amount is large and proceeding to the image signal generation step Sa1 without performing the frame algorithm if the change amount is small.

Wherein the frame algorithm includes: determining whether a pixel of the high-speed sub-frame includes a gradation of 200 gradations or more; And the pixel not including the gradation of 200 gradations or more may directly go to the image signal generating step Sa1 and may include directly displaying the pixel including the gradation of 200 gradations or more without any change .

Wherein the time division display method further comprises applying a fast frame algorithm to the input frame before the image signal generation step Sa1, wherein the fast frame algorithm applying step includes interpolating interpolation) into four high-speed sub-frames; Generating a signal applied to each pixel of the generated sub-frame by performing the image signal generation step Sa1 to the sub-frame generation step Sa3 based on the average luminance of the high-speed sub-frame; And adjusting the order of the generated subframes so that the subframe having the highest gray level is output first based on the plurality of video signals of each pixel of the subframe.

According to an aspect of the present invention, there is provided a time-division display method for displaying an image at a frequency higher than a frame frequency of an input video signal, A dithering step (Sb1) of performing image processing so as to be dither-dithered with at least one adjacent pixels having a similar luminance; A mixing step (Sb2) for mixing the consecutive two frame luminance by exchanging the darkness and brightness of the pixel in the next frame with respect to the video signal of the dithering pixel; And a step (Sb3) of generating a plurality of subframes by dividing the mixed frame based on the gradation of the subframe determined for each pixel.

The generating of the sub-frame may include generating a sub-frame image signal so that the sub-frame image signal is displayed at three gradation levels of a dark gray level, a bright gray level, and a middle gray level.

The mixing step Sb2 includes dividing the input frame into an even-numbered frame and an odd-numbered frame. And an up frame gray level signal which is a frame signal including a bright gray level is given to one pixel and a gray level signal is supplied to the other pixel in correspondence to the pixels of the odd frame and the corresponding pixels of the even frame adjacent to the odd frame And a step of providing a down frame gradation signal that is a frame signal including the frame signal.

(I, j) -th pixel of the odd-numbered frame, the up-frame gradation signal is given if i + j is an odd number, and the up- Frame to the (i, j) -th pixel of the even-numbered frame, and if the i + j is an odd number, applying the down-frame gradation signal, and if i + j is an even number, can do.

Dividing the gray level signal according to the color of each pixel of the input frame; The gray level of the B or R pixel is Rm (the maximum gradation value of the R pixel) or Bm (the maximum gradation value of the R pixel) when the pixel is the G pixel and the mixing step Sb2 is not performed, The highest gray level value of the B pixel), the M region where the gradation of the down frame mainly changes, and the G region where the gradation of the up frame mainly changes. And the pixel belonging to the H region does not perform the mixing step (Sb2) with respect to the divided region, and the pixels belonging to the M and G regions are supplied with different types of up frame gray level signals and down frame gray level signals Step < / RTI >

A method for displaying an image at a frequency higher than a frame frequency of an input video signal, comprising the steps of: inputting a plurality of pre-input lookup tables or image conversion logic Providing a sub-frame gradation division scheme (Sc1); (Sc2) analyzing a relative size of the R, G, and B gradation levels corresponding to each pixel of the input image signal; And a step (Sc3) of applying different sub-frame division schemes among the plurality of sub-frame gradation division schemes to the R, G and B pixels according to the relative sizes of the analyzed R, G, and B gradations have.

In the sub-frame segmentation scheme applying step (Sc3), as a result of the size analysis, a segmentation scheme having a low value of a side gamma curve is applied to a pixel of the first color having the lowest gradation value, A method of applying a dithering method in which a method in which a side gamma curve has a high value is appropriately mixed is used.

In the sub-frame dividing scheme application step Sc3, the plurality of gradations corresponding to the sub-frame of each pixel are divided into a substantial black gradation (gradation close to 0 or 0), a substantial white gradation (gradation close to 255 or 255) And dividing an image frame input to include the gradation M into a plurality of subframes, wherein the number of subframes displayed by the intermediate gradation (M) among the plurality of gradations is one to n And the intermediate gradation M can be determined by measuring the average luminance appearing while changing the gradation of the subframe.

Generating four subframes by time-sharing the input frame,

And dividing the subframe into four regions (a low gradation region, a relay region, a high gradation region, and a highest gradation region) according to a gradation level of a plurality of image signals of each pixel.

The plurality of sub-frame gradation division schemes include (a) a low gradation region (0 to 255,0,0,0), and a low gradation region (a, b, c, d) A sub-frame b, a sub-frame c, a sub-frame c, and a sub-frame d, wherein 0 to 255 are implemented as sub-frames corresponding to the corresponding sub- 0 means a gray scale value of 0 or a gray scale value close to 0, 255 means a gray scale value of 255 or a gray scale value close to 255 -, and a relay adjustment region 255,0 to 255,0,0 255, 255, 255, and 255, and the highest gradation region 255, 255, 255, 255, and 255; 255, 0, 255, 0, 255), the highest gradation region (255, 255, 255, 0 to 255) ; (c) The gradation range (0 to 255, 0, 0, 0), the used gradation range (255, 0 to 255, 0 to 255, 0) and the highest gradation range (255, 255, 255, 0 to 255) Split method; 0 to 255, 0 to 255, 0 to 255, 0 to 255, 0 to 255, 0 to 255, and 0 to 255 in the high gradation range (d) ); And (e) a method of dividing all the sub-frames (0 to 255, 0 to 255, 0 to 255, and 0 to 255) for the entire gradation region.

In the sub-frame dividing scheme applying step (Sc3), the method (a) is applied to the pixels of the first color having the lowest gradation value as a result of the size analysis, and the color of the pixels of the sub- (B), (c), and (c) are performed for the adjacent pixels in the number proportional to the difference between the gray-level values of the pixels of the second color and the pixels of the first color among the adjacent pixels of the pixels of the second color, (d) and (e) schemes may be applied.

According to an aspect of the present invention, there is provided a time-division display method including: a time-division step of time-dividing an input image frame into a plurality of sub-frames and dividing an image signal for each sub-frame; And a display step of displaying an image based on the divided image signal, wherein a liquid crystal response speed (Ton + Toff) between a black image and a white image of each pixel of the panel displaying the image is 10 msec Can have a smaller value.

In order to achieve the above object, a liquid crystal display device includes a plurality of subframes (f1, f2, f3, ..., fn) for inputting an image frame to display an image at a frequency higher than a frame frequency of an input video signal A plurality of image signals having different brightnesses from an input image signal for each pixel among the pixels constituting the input frame, the average of the brightness of the plurality of image signals being different from the input A video signal generator for generating substantially the same luminance as the video signal; A gradation determining unit for determining a gradation for each subframe based on the gradation of a plurality of image signals of each pixel generated, wherein the number of generated image signals corresponds to the number of subframes; A subframe generator for generating a plurality of subframes based on the determined gray level of the subframe and the generated plurality of video signals; And a display unit for displaying the generated sub-frame, wherein the gradation applied to the sub-frame includes a substantial black gradation (gradation close to 0 or 0), a substantial white gradation (gradation close to 255 or 255) And may be composed of combinations of three or less gradations including the gradation M.

According to an aspect of the present invention, there is provided a liquid crystal display device for displaying an image at a frequency higher than a frame frequency of an input image signal, the liquid crystal display device having an average luminance equal to an average luminance of an input image frame, A dithering unit for performing image processing to be dithered with at least one adjacent pixels having similar luminance; A mixing unit for mixing the consecutive two frame luminance by exchanging the darkness and brightness of the pixel in the next frame with respect to the video signal of the dithering pixel; And a subframe generator for generating the plurality of subframes by dividing the mixed frame based on the gray level of the subframe determined for each pixel.

According to an aspect of the present invention, there is provided a liquid crystal display device capable of displaying an image at a frequency higher than a frame frequency of an input image signal, A driving circuit for providing the plurality of sub-frame gradation division schemes through a look-up table or image conversion logic; A gradation level analyzer for analyzing relative sizes of R, G and B gradation levels corresponding to each pixel of the input image signal; And a sub-frame dividing method for applying different sub-frame dividing methods among R, G, and B pixels among the plurality of gray-scale division methods (functions) of the plurality of sub-frames according to the relative sizes of the R, Section.

According to an aspect of the present invention, there is provided a liquid crystal display device including a time division unit for time-dividing an input image frame into a plurality of subframes and dividing an image signal for each subframe; And a display unit for displaying an image based on the divided image signal, wherein a response speed (Ton + Toff) of a liquid crystal between a black image and a white image of each pixel of the panel of the display unit is less than 10 msec have.

The difference between the gray voltage 0 (V _0gray) and the common voltage (Vcom) of a TFT (Thin Film Transistor) of the panel may be less than 0.7 volts.

The pixels of the panel may be formed of anisotropic liquid crystal with a low dielectric constant having a ratio of a dielectric constant in a major axis and a minor axis direction of a liquid crystal director is 0.6.

The white voltage Vmax of the TFT of the panel may be 7 volts or more larger than the common voltage Vcom.

INDUSTRIAL APPLICABILITY According to the time-division display method and the liquid crystal display device of the present invention, it is possible to enhance side viewability while maintaining the same front viewability in the time division.

In addition, according to the time-division display method and the liquid crystal display device of the present invention, there is a problem that it is sensitive to a change in luminance according to temperature, a problem that gamma tuning is not easy, a high frame frequency method and a time- 3D technology of the collision with the problem is overcome.

1 is a block diagram schematically showing a configuration of a liquid crystal display device according to an embodiment of the present invention;
2 is a detailed block diagram specifically illustrating a controller of a liquid crystal display device according to an exemplary embodiment of the present invention,
3 is a conceptual diagram for explaining a subframe time division method according to an embodiment of the present invention,
4 is a graph for experimentally determining the gradation of each subframe according to the target gradation,
FIG. 5 is a flowchart illustrating an operation of a liquid crystal display device according to an exemplary embodiment of the present invention,
Figure 6 is a graph and graph associated with function f,
FIG. 7A is a graph showing a front gamma curve and a side gamma curve of a gray level application scheme for each subframe according to an area of a liquid crystal display device according to an embodiment of the present invention,
FIG. 7B is a detailed block diagram illustrating a sub-frame generation unit of a liquid crystal display device according to an exemplary embodiment of the present invention,
8A is a graph showing a response waveform of a high-speed and low-speed response liquid crystal when a voltage of a VA liquid crystal cell is applied,
8B is a graph showing response waveforms of high-speed and low-speed response liquid crystals when ON voltage is applied to a VA liquid crystal cell for 4 msec,
8C is an exemplary view of the temperature distribution of the panel,
FIG. 9 is a block diagram illustrating an interlocking relationship between a two-frame mixing unit and a subframe time-division unit of a liquid crystal display device according to an exemplary embodiment of the present invention;
10 is a view for explaining the concept of two frame mixing of a liquid crystal display device according to an embodiment of the present invention,
11 is a view for explaining the concept of a luminance flicker and a color flicker,
12A is a graph in which regions are divided by the characteristics according to the up / down frame gradation of the target gradation of the B pixel,
FIG. 12B is a graph in which regions are divided by the characteristics according to the up / down frame gradation of the target gradation of the G pixel,
12C is a graph in which regions are divided by the characteristics according to the up / down frame gradation of the target gradation of the R pixel,
FIG. 13 is a detailed block diagram illustrating a two-frame mixing unit according to an exemplary embodiment of the present invention.
14 is a block diagram for explaining an interlocking relationship between a fast frame algorithm application unit and a subframe time division unit in a liquid crystal display device according to an embodiment of the present invention;
15 is a flowchart illustrating an operation of a fast frame algorithm according to an embodiment of the present invention.
16 is a flowchart illustrating an operation of a fast frame algorithm according to another embodiment of the present invention,
17 is a graph showing the relationship between liquid crystal response speed and visual perception,
18 is a view for explaining a relationship between a voltage and a capacitance in a TFT and a pixel of a panel of a liquid crystal display device according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

Liquid crystal display device general

1 is a block diagram schematically showing a configuration of a liquid crystal display device according to an embodiment of the present invention. 1, a liquid crystal display device according to an exemplary embodiment of the present invention includes a frame memory 110, a controller 120, a gate driver 130, a data driver 140, a panel 150, (Not shown).

Referring to FIG. 1, a frame memory 110 stores an input image signal which is connected to a controller 120 and is input to a controller 120. The controller 120 can control an image signal stored in the frame memory 110. [

The controller 120 controls signals applied to each pixel 155 of the panel 150 based on the input image signal. The controller 120 may time-divide an input frame. The controller 120 may time-divide the input image frame into two or more subframes by multiplying the frame frequency of the input image frame. The controller 120 also divides the video signal associated with the pixel 155 of each subframe into subframes.

At this time, when the subframe is generated using the subframe time division scheme, the controller 120 sequentially adjusts the brightness of the subframe in order to solve the difficulty of gamma tuning and the sensitivity problem of luminance change according to temperature And the order of the subframes and the implementation scheme can be determined so that the subframe is brightened or sequentially brightened. That is, the controller 120 can be implemented such that bright subframes and dark subframes are clearly separated in order to dramatically improve the side viewability. The controller 120 may use a method of dividing the gradation into four regions to determine a detailed gradation level to determine a gamma curve for the subframe and determining an implementation method for each subframe of the divided region have.

Then, the controller 120 can use the two-frame mixing technique and the high-speed frame algorithm to maximize the effect of the side viewability and the effect of the subframe time division operation.

The controller 120 may generate and output a gray-scale data signal by applying different look-up tables according to the positions of the pixels 155 of each sub-frame, for each of the time-divided sub-frames. That is, the controller 120 generates the gate driving control signal of the gate driving unit 130 and the data driving control signal of the data driving unit 140, and transmits them to the gate driving unit 130 and the data driving unit 140, respectively.

The gate driver 130 receives the gate driving control signal supplied from the controller 120, sequentially generates scan pulses and supplies the generated scan pulses to the gate line 135. According to the embodiment of the present invention, the gate driver 130 sequentially supplies scan pulses to the gate lines 135 during the driving period of the odd-numbered subframe among the subframes whose frame frequency is increased by the controller 120 A scan pulse may be supplied to the gate line 135 during the driving period of the odd sub-frame. In addition, the gate driver 130 turns on or off the TFT of the LCD panel 150 according to the scan pulse.

The data driver 140 provides a constant voltage to the pixel 150 based on the data driving control signal received from the controller 120. The data driver 140 receives the gamma voltage according to the image signal and provides the gamma voltage to the pixel 155 of the LCD panel 150. The data driver 140 converts the received image signal into an analog image signal and transmits the analog image signal to the data line 145 formed in the LCD panel 150.

The LCD panel 128 receives the scan pulse and the analog image signal from the gate driver 124 and the data driver 126 through the gate line and the data line and transmits a signal to each pixel in the panel to display the image . The LCD panel 128 can display an image at a frame frequency of 2 to 4 times by dividing a video signal of an input frame. For example, an image can be displayed at a high frame rate of 120 Hz to 240 Hz.

In the embodiment of the present invention, the LCD panel 150 may be configured by injecting liquid crystal between two glass substrates. On the lower glass substrate of the LCD panel 150, the data line 145 and the gate line 135 are orthogonal. A TFT (Thin Film Transistor) may be formed at an intersection of the data line 145 and the gate line 135. The TFT supplies data on the data line 145 to the liquid crystal cell in response to the stanch pulse. The gate electrode of the TFT may be connected to the gate line 135, and the source electrode of the TFT may be connected to the data line 145.

In the preferred embodiment of the present invention, the response speed (on + off) of the liquid crystal between the black image and the white image of the pixels 155 constituting the LCD panel 150 may have a value lower than a constant speed. Particularly, in order to secure the characteristics of the optimized panel 150 level among the conventional pixel division techniques,

The temperature sensor 160 senses the temperature distribution of the LCD panel 150. The temperature sensor 160 may be plural. The plurality of temperature sensors 160 may measure the temperature at predetermined time intervals to reflect the reaction of the external conditions.

Implementation of subframe time division scheme

2 is a detailed block diagram specifically showing a controller 120 of a liquid crystal display device according to an embodiment of the present invention. 2, the controller 120 according to an exemplary embodiment of the present invention includes a video signal generating unit 210, a gray-level determining unit 220, a sub-frame generating unit 230, and a display signal applying unit 240 ).

Referring to FIG. 2, the video signal generation unit 210 divides a display method for displaying a 60-Hz video signal into a plurality of images based on a plurality of sub-frames in each frame to generate a plurality of video signals have. At this time, the input video signal can be divided into two, three, and four. From the viewpoint of the side view, it is preferable to have four subframes because the side image quality increases as the number of subframes increases. In the case of having four subframes, an image frame of 60 Hz can be divided into subframes of 240 Hz, and the image signal can also be divided into respective image signals for each subframe. At this time, the video signal generation unit 210 may use a method of interpolating selected two frames by selecting consecutive input frames during frame division and video signal division. At this time, since a plurality of subframes must be viewed at the same luminance as the input frame, the luminance average value of the generated plurality of video signals is equal to the luminance of the input image frame. The video signal can be generated in a number corresponding to the number of subframes.

The gray-level determining unit 220 determines a gray-level for each sub-frame according to the gray-scale level of each pixel of the time-divided video signal through the video signal generating unit 210. Since the average brightness of each subframe must be equal to the brightness of the input image as described above, the gray level determining unit 220 determines the gray level of the subframe, The gray level can be determined by measuring the average luminance of the subframe.

According to an embodiment of the present invention, the gray-level determining unit 220 can determine a substantial black gradation (0), a substantial white gradation (255) and a variable intermediate gradation (M) The gradation can be determined so that the gradations are combined and realized. Here, the intermediate gradation M is a value between 0 and 255 gradations and can be determined by measuring the average luminance appearing while changing the gradation as described above.

The subframe generator 230 generates a plurality of subframes based on the plurality of image signals generated through the image signal generator 210 and the gradation level determined through the gradation determiner 220. It is possible to arrange a plurality of video signals in accordance with the number of subframes to be generated and to generate the subframe by using the gradation determined by the gradation determining section 220 for each subframe. At this time, the display order of the subframes for each gradation may be a dark gradation to a bright gradation order, a bright gradation to a dark gradation order, or a subframe to be displayed in a sequence in which the two orders are circulated.

The display signal applying unit 240 applies a control signal to the panel 150 to display the generated sub-frame.

3 is a conceptual diagram illustrating a subframe time division scheme according to an embodiment of the present invention. As shown in FIG. 3, a display for displaying a 60-Hz image signal is a method for outputting one image corresponding to a display device within 1/60 seconds of an input image signal of 60 Hz. On the other hand, the time division technique generates a plurality of images having a plurality of sub-frames in each frame, and displays the generated images through a display device. That is, the first frame may be divided into four subframes of subframe a, subframe b, subframe c, and subframe d. As described above, it may be divided into two or three subframes, but it is preferable to divide into four subframes in terms of side viewability. Therefore, it is assumed that the subframe is divided into four subframes.

The controller 120 of the embodiment of the present invention can use the following display scheme to effectively implement the subframe time division technique.

VB -> B -> D -> VD when displaying the brightness of the subframe in the brightness order VB (very bright), B (bright), D (dark) VD - > D- > B- > VB. This is because the fastest response characteristic occurs when the brightness is gradually darkened from bright to dark due to the original problem of the slow response liquid crystal, or sequentially brightened, resulting in a time division effect. However, at this time, if you attach multiple frames to VB -> B -> D -> VD, B -> D -> VD -> VB, D -> VD -> VB -> B and VD -> VB -> B -> D The same result will be given when it is released. VD -> D -> B -> VB is the same as D -> B -> VB -> VD, B -> VB -> VD -> D and VB -> VD -> D -> B. That is, in order to improve the side viewability in the time division driving technique, the bright sub-frame and the dark sub-frame must be clearly separated. In order to achieve this, the luminance must be continuously increased or continuously darkened.

According to the embodiment of the present invention, when the gradation is determined as a combination of three gradations, the order of gradation according to the sub-frame order is in the order of dark gradation to bright (such as 0- > 0- > M-> 255) (255 -> 0 -> 0 -> M), (M -> 255 -> 0 -> M -> 255 -> M -> M -> 0) > 0), (M -> M -> 0 -> 255) and (M -> 0 -> 255 -> M)).

ii) Also, as a method for implementing the gamma curve for the sub-frame most effectively, the following method can be considered. It can be divided into four regions according to the gradation level. For example, A: 0 to 110 gray, B: 110 to 180 gray, C: 180 to 230 gray, and D: 230 to 255 gray. Let the gradations separating the regions be b1 (boundary 1), b2, b3. In the above example, b1, b2, and b3 correspond to 110, 180, and 230 gray levels. At this time, the A region is responsible for the subframe a, the B region is the subframe b, the C region is the subframe c, and the D region is the subframe d. Therefore, according to the gradation, the A region is implemented as (a sub-frame, b sub-frame, c sub-frame, and d sub-frame) = (0 to 255, 0, 0, 0). Here, (0 to 255, 0, 0, 0) represents any one of 0 to 255 gradations in a sub-frame, and 0 or 0 in b, c, and d subframes .

Similarly, the B area is implemented as (255, 0 to 255, 0, 0), the C area is implemented as (255, 255, 0 to 255, 0) , 0 to 255). Here, 255 means to implement with a gradation close to 255 or 255.

According to an embodiment of the present invention, since the gradation of each subframe can be expressed by three, the detailed gradation of the gradation represented by 0 to 255 in the a, b, c, and d subframes is determined by the gradation determination unit 220 (M), which is determined by the gray-scale level (M).

In addition to the above-described implementation, the A region and the B region are (0 to 255, 0 to 255, 0, 0), the C region is (255, 255, 0 to 255, 0) , 255, 255, 0 to 255) may be used. However, since the separation of the A and B regions is not clear in this method, the side viewability may be somewhat deteriorated.

255, 0, 0, 0), the B and C areas (255, 0 to 255, 0 to 255, 0) and the D area (255, 255, 255).

The area A is set to (0 to 255, 0, 0, 0), the area B is set to (255, 0 to 255, 0, 0), the areas C and D are set to 255, 255, 0 to 255, 255), or a scheme implemented on all subframes (0 to 255, 0 to 255, 0 to 255, 0 to 255) for the entire gradation region, that is, a non-divided structure may be used. The non-time-division structure is the worst visibility structure.

iii) In the previous method, a method for determining b1, b2, b3 as the criterion for dividing the area into A, B, C and D is as follows. (255, 0, 0, 0), (255, 255, 0, 0) and (255, 255, 255, 0) gradations for the image signals of the sub- B2, and b3 corresponding to the average luminance obtained when the luminance is obtained. For example, when inputting 255, 0, 0, 0, 255, 255, 0, 0, 255, 255, 255, The grayscale is 110, 180, and 230, respectively, according to the equation of grayscale = (L / 100) ^ (1 / 2.2) * 255, assuming 15.7%, 46.5%, 79.6% . Thus, the values of b1, b2, and b3 can be found simply.

When b1, b2, b3 are determined, the gray scale of each zone is determined. The details of this can be obtained through relatively simple experiments. By measuring the average luminance appearing while changing the signal of the subframe a from 0 to 255 as in the case of (0 to 255, 0, 0, 0) and finding the corresponding grayscale, Can be determined. By measuring the average luminance appearing while changing the gradation of the sub-frame b from 0 to 255 as in the above method (255, 0 to 255, 0, 0) and mapping the corresponding gradation, . The gradations of the C and D regions are determined by measuring the average luminance by inputting (255, 255, 0 to 255, 0) and (255, 255, 255, 0 to 255) in the same manner.

However, according to an embodiment of the present invention, since the number of the gradations of each subframe can be limited, the detailed gradation of the gradation expressed by 0 to 255 in the a, b, c, and d subframes is determined by the gradation determiner 220 (M), which is determined by the gray-scale level (M).

4 is a graph for experimentally determining the gradation of each sub-frame according to the target gradation. As can be seen from FIG. 4, for the sub-frame a, the average luminance can be measured while changing the gradation from 0 to 110 for the sub-frame a, while for the sub-frame b from 110 to 180, The detail gradation can be determined by measuring the average luminance while changing the gradation from 180 to 230 for the frame c and from 230 to 255 for the sub frame d.

5 is a flowchart illustrating an operation of the liquid crystal display device according to an exemplary embodiment of the present invention, after the input signal is received, until the signal is output. Referring to FIG. 5, when an input signal Gi of 60 Hz is input, the controller 120 stores the input signal Gi in the frame memory 110 (S510). At this time, the number of the frame memories 110 may be two or more. This is because the signal of the previous frame should be divided into 240 Hz and transmitted to the panel 150 while the current frame is stored. Then, the controller 120 counts the subframe (S520). (S530, S532, S534, and S536) by referring to the logic or lookup table 505 corresponding to each subframe. At this time, logic calculation can be performed through a method of referring to a lookup table or a method of following a logic, and a method of forming a grayscale can be used effectively because it has more various applicability. More specifically, the sub frame a generates an application signal with reference to a lookup table and logic for a pixel in a region where the gradation of the input signal is smaller than b1 (S530). In the subframe b, 255 gradations are implemented for the pixels of the area where the gradation of the input signal is smaller than bi, and an application signal is generated by referring to the lookup table and the logic for the pixels of the area larger than b1 and smaller than b2 do. The region having a value larger than b2 is implemented as 0 (S532). The sub-frame c implements the gradation of 255 in the area of the area where the gradation of the input signal is smaller than b2 and generates the application signal by referring to the lookup table and the logic in the area of the area which is larger than b2 and smaller than b3 do. The pixel of the region where the gradation of the input signal has a value larger than b3 is set to 0 (S534). In the subframe d, 255 gradations are implemented for the pixels of the area where the gradation of the input signal is smaller than b3, and an application signal is generated by referring to the lookup table and the logic for the pixels of the area having the value larger than b3 (S536 ).

Then, the generated signal is output to the panel 150 (S540).

Here, the method of forming the logic will be described in more detail. The function determined in FIG. 4 may be formed of logic. For example, if the gradation value of the input signal is Gi, then Gi requires logic to separate the gradation into four subframes such as (Ga, Gb, Gc, Gd).

Ga crystal: if Gi < b1, then Ga = F (Gi).

                if Gi ≥ b1, then Ga = 255.

      Gb determination: if Gi < b1, then Gb = 255.

                if b1? Gi <b2, then Gb = G (Gi).

                if b2 &lt; = Gi, then Gb = 0.

      Gc determination: if Gi < b2, then Gc = 255.

                if b2 < Gi &lt; b3, then Gc = H (Gi).

                if b2 &lt; = Gi, then Gc = 0.

      Gd determination: if Gi < b3, then Gd = 255.

                If b3 &lt; = Gi, then Gc = K (Gi).

F (Gi), G (Gi), H (Gi), and K (Gi) At this time, you can change these functions as follows.

F (Gi) = 255 * f (Gn), where 0 ≤ Gn ≡ (Gi / bi) ≤ 1, 0 ≤ f ≤ 0, and the domain and region are normalized. The f function can be obtained by a polynomial function. However, in practice, intermediate values can be found by interpolating by storing a plurality of coordinate values between 0 and 1 in the domain and region as a look-up table. For example, if the function corresponding to the frame 1 of FIG. 4 is normalized, it can be expressed as shown in FIG. 6A.

6 is a graph and a graph associated with function f. By using the lookup table shown on the right side of FIG. 6A, an arbitrary function value f (a) can be found by taking an intermediate value between two adjacent points. For example, when b1 = 110 and G1 = 80, f (80/110) = f (0.7273) = f (0.7) + {f , And the final F (Gi) = 255 * f (80/110).

Similarly,

F (Gi) = 255 * f (Gn), where Gn? (Gi / bi)

G (Gi) = 255 * g (Gn), where Gn? (Gi-b1) / (b2-

H (Gi) = 255 * h (Gn), where Gn? (Gi-b2) / (b3-

Gn = (Gi-b3) / (255-b3) where K (Gi) = 255 * k

, And the values of each normalized gradation, Gn and functions f, g, h, and k are between 0 and 1.

Hereinafter, a method for determining a color scheme in consideration of color characteristics of each pixel in a subframe will be described.

As described above, the 240 Hz standard time division method can be variously implemented. That is, the sub-frame generator 230 may select one of various methods and implement gradations for each sub-frame in a selected manner.

When a gradation of four consecutive sub-frames is represented by a specific region (a, b, c, d), for a pixel belonging to a specific region, a is a first sub-frame, b is a second sub- 0 &quot; means a period in which 0 is a gray level value of 0, 255 is a gray level value of 255, and &quot; 0 &quot; Value.

According to the embodiment of the present invention, the controller 120 is configured to (a) display a low tone area (0 to 255, 0, 0, 0), a relay tone area (255 to 0 to 255, 0, 0) 255, 255, 0 to 255, 0) and the highest gradation region (255, 255, 255, 0 to 255). At this time, in the portion indicated by 0 to 255, the gradation can be selected between 0 and 255 for the gradation. For example, the low gradation area can be displayed by varying the first sub frame gradation. (a) The method is a representative time-sharing method as described above.

In addition, the controller 120 has a function of (b) a low gradation range (0 to 255, 0 to 255, 0, 0), a high gradation range (255, 255, 0 to 255, 0) 255, 0 to 255). This method is a method of applying the low relay region to the first second subframe at the same gray level. As compared with the method (a), the side viewability of the low gray level region is somewhat lower.

255, 0, 0, 0), a used gradation range (255, 0 to 255, 0 to 255, 0), a highest gradation range (255, 255, 255, 0 to 255 ). The second third subframe data is applied in similar gradation with a similar concept as in (b) above. (A) in the second gradation region.

0, 255, 0, 0, 0), the high-gradation region (255, 255, 0 to 255, 0 To 255). This also applies the third and fourth subframe data with a similar gradation in a concept similar to (b). (A) in the high-to-highest gradation region.

Next, (e) non-time division structure: a method of applying the same gradation (0 to 255, 0 to 255, 0 to 255, 0 to 255) to each subframe in the entire gradation region can be used. This is the worst way of visibility.

Actually, there may be more various methods besides the above five, but in fact, the best method from the viewpoint of side view is (a) method. However, since the combined technique of the above methods can be superior to the technique using alone (a), the controller 120 can use it variously.

FIG. 7A is a graph showing a front gamma curve and a side gamma curve of a method of applying gray-scale for each sub-frame according to an area of a liquid crystal display device according to an embodiment of the present invention.

Referring to FIG. 7A, in all gamma implementation methods, the frontal gamma curve is the same since the frontal brightness can be adjusted equally. Therefore, the front visibility is the same regardless of any of the above methods. On the other hand, the gamma curve of the side differs according to which method is used as shown in FIG. 7A. Therefore, (a) is the most excellent method.

FIG. 7B is a detailed block diagram illustrating a sub-frame generation unit 230 of a liquid crystal display device according to an exemplary embodiment of the present invention. 7B, the subframe generator 230 according to an exemplary embodiment of the present invention may include a color characteristic estimator 710, a gradation level comparator 720, and a decision unit 730 have.

Referring to FIG. 7B, the color characteristic determination unit 710 determines a chromatic characteristic of each pixel of a subframe. That is, it is determined whether the color of the signal applied to the pixel of the panel is R, G, or B.

The gradation level comparator 720 compares the gradation level values of the R pixel, the G pixel, and the B pixel based on the identified color characteristics. When a certain pixel has (R, G, B) pixel data, the color of the side appearing due to the pixel data has chroma lower than that of the front color. As can be seen from the gamma curve of FIG. 7A, since the gamma curve shows a gentle curve on the side, the luminance difference between the R, G and B data decreases. In order to compensate for this, the lateral color may be improved by increasing the lateral luminance of the data with high gradation. Therefore, the above-described various gamma display methods are used to perform such a complement. That is, the gradation indicating the highest gradation among the R, G, and B pixel data values found in the color characteristic determination unit 710 is the best in the other method (a) And another method is applied to the halftone. To this end, the gradation level comparator 720 compares the gradation values in the data values of the respective R, G, and B pixels with each other to calculate a pixel having the largest gradation, a pixel having the highest gradation, .

As a result of the comparison of the gradation level comparator 720, the method determination unit 730 applies an implementation scheme that can exhibit the best side viewability to the pixel of the hue having the lowest gradation, and determines the highest gradation and the middle gradation It is determined to apply a different method to the color pixel. That is, the method (a) is applied to the lowest gradation, and the method other than the method (a) is applied to the highest gradation and the middle gradation.

According to the first embodiment of the present invention, the method determining unit 730 may apply a pixel dithering method to more effectively display the color of the side surface.

For example, when it is assumed that R <G <B, the R pixel having the smallest gray level value can be applied to all the (a) method as described above, To be applied. Particularly, for the B pixel, the number of pixels corresponding to the (BR) gradation difference for the adjacent four, six, or nine pixels corresponds to the non-visible gamma (e) or other (b) .

(B) to (d) apply to one of nine adjacent pixels, (b) to (b) for eight pixels,

30 ≤ (B-R) <50: (b) - (d) applies to two of nine adjacent pixels, (a)

50 ≤ (B-R) <70: (b) to (d) apply to three of nine adjacent pixels, (a)

70 ≤ (B-R) <90: (b) to (d) apply to four of the nine adjacent pixels, (a)

90 ≤ (B-R) <110: (b) to (d) apply to five of the nine adjacent pixels, (a)

110 ≤ (B-R) <130: (b) to (d) apply to six of nine adjacent pixels, (a)

130 ≤ (B-R): Apply the method (b) to (d) to seven of the nine adjacent pixels and apply the method (a) to two.

In the same manner, the method determining unit 730 may apply a dithering method to the G pixel according to the value of (G-B).

In the above dithering method, the positions of the pixels to which the gradation different from the gradation (a) are applied can be sequentially changed so that the same luminance is displayed on average.

Gamma tuning to different panel temperatures

One of the problems with the time division method is that the brightness varies depending on the response speed of the liquid crystal. The reason is that the brightness is slightly increased when the response speed of the liquid crystal is slow when the instantaneous voltage is applied in the black state, whereas the brightness is greatly increased when the response speed of the liquid crystal is fast. Therefore, when the response time of the liquid crystal is fast, when the same time-divisional image data is applied, the brightness is brightened and the gamma curve is distorted. Accordingly, when the response speed of the liquid crystal is changed, the image quality of the panel is distorted.

8A is a graph showing a response waveform of a high-speed and low-speed response liquid crystal when a voltage of a VA liquid crystal cell is applied. As shown in FIG. 8A, the fast response liquid crystal and the slow response liquid crystal respond differently to the instantaneous signal waveform changes.

8B is a graph showing response waveforms of a high-speed and low-speed response liquid crystal when ON voltage is applied to a VA liquid crystal cell for 4 msec. In a waveform shown in time-divisional driving, as shown in FIG. 8B, The average luminance of the high-speed response liquid crystal is higher than the average luminance of the low-speed response liquid crystal.

The liquid crystal decreases in viscosity as the temperature rises. As a result, the response speed tends to increase as the temperature rises. As described above, the VA-LCD to which the time-division driving is applied exhibits a phenomenon in which the gamma value of the gamma curve of the screen is lowered as the panel temperature increases, that is, the average brightness of the screen is increased. For this reason, an algorithm is required to readjust the gamma curve according to the temperature.

However, since the temperature of the panel continuously changes according to the environment or the BLU structure and a considerable temperature difference occurs depending on the position of the panel, it is very difficult to adjust the gamma curve by temperature for each position .

This problem can be solved by using the above-described time-division driving method. Experiments have shown that when the response speed of the liquid crystal changes, the gamma curve is distorted as a whole, but the normalized functions f, g, h, and k are hardly changed. Thus, the gamma determination method associated with the normalization function of Figs. 5 and 6 is valid. However, the values of b1, b2 and b3 are different only. As the temperature rises, these values rise. Therefore, it is possible to perform gamma tuning according to the temperature in the following manner.

1) First, the temperature distribution of the panel is sensed through the temperature sensor 160. At this time, a plurality of temperature sensors 160 and a general temperature distribution formula of the panel obtained through experiments are used. Generally, the temperature of the region where the LED lamp is attached is high, and the temperature of the region where it is not is low. 8C is a diagram showing an exemplary view of the temperature distribution of the panel. A temperature mapping of the distribution as shown in Fig. 8C can be obtained. The temperature sensor 160 re-measures the temperature distribution at predetermined time intervals to reflect the reaction of the external conditions.

2) Based on the temperature mapping thus obtained, a map of b1, b2, b3 is formed. Map high values of b values in the high temperature region and map low values of b in the low temperature region. Conditions can be easily found through experiments.

3) Input the found b values into the gamma determination conditions (see FIGS. 5 and 6) as described above so that the modified gamma values are applied to the panel.

This method can be applied when the panel conditions have changed, when the gamma adjustment is necessary.

two frame Mixing

FIG. 9 is a block diagram illustrating an interlocking relationship between a two-frame mixing unit and a subframe time-division unit of a liquid crystal display device according to an exemplary embodiment of the present invention. 9, the liquid crystal display apparatus according to an exemplary embodiment of the present invention may include a two frame mixing unit 910 and a subframe time division unit 920. [ Here, the subframe time division unit 920 is a component that performs time division through a subframe described in the description up to FIG. 8B.

Referring to FIG. 9, the two-frame mixing unit 910 performs a preprocessing process on an image signal input to the subframe time division unit 920. That is, an image input signal of 60 Hz is converted into an up / down mixed signal and is transmitted to the subframe time division unit 920. This is to maximize the effect of improving time-share-side visibility. That is, the combination of the time division performed in the subframe time division unit 920 and the spatial division to generate the luminance difference between the pixels is performed.

The subframe time division unit 920 receives the up / down mixing signal generated by performing the conversion in the two frame mixing unit 910, performs time division to generate a subframe, After dividing into a plurality of regions based on the gradation level, a sub-frame-by-sub-frame implementation method is determined and a signal is applied to each pixel.

Hereinafter, the operation of the two-frame mixing unit 910 will be described in detail.

As described above, the method for improving the time-division-by-side visibility is less effective than the pixel division method. Therefore, there is a further need for a way to improve the lack of visibility by applying new methods.

In the present invention, it is possible to consider convergence with the two-frame mixing method, which is a driving technique capable of amplifying the side picture quality by being fused with the sub-frame time division technique.

The sub-frame time-division method described above is a method of transforming a signal input at 60 Hz to 240 Hz. Since different image data is applied to the four sub-frames, the luminance profile of each pixel actually has 60 Hz. However, another method is to use the temporal mixing method between the current frame and the next frame to produce a pixel segmentation effect.

10 is a view for explaining the concept of two frame mixing of a liquid crystal display device according to an embodiment of the present invention. Referring to FIG. 10, for example, if the signals inputted to the first and second frames in the first R1 in the upper left corner are equally 150 gray, in the two frame mixing method, 200 gray as the first frame and 200 gray as the second frame, The same luminance can be obtained on average by inputting 56 gray as R2. When a signal R1 having the same gray level is input to the consecutive frames, a signal having a bright gray level and a gray level signal are generated in the first frame R0 and the second frame R2 to obtain an average, To be the same gradation. That is, the input of the R1 signal twice is converted into the input of R0 and R2, respectively. R0 and R2 are respectively a signal of a bright tone and a signal of a dark tone, and the order may be reversed.

As described above, the two-frame mixing method is a method of generating the input average luminance by combining two consecutive frames.

However, when the two-frame mixing method is used, the luminance of each pixel oscillates at 30 Hz, which is recognized as a flicker phenomenon, and this method can not be practically used. Therefore, the two frame mixing method should be applied in a way that flicker is not recognized.

The maximum frequency at which the flicker is viewed is called the critical flicker frequency (CFF), which is known to be proportional to the average luminance of the area that is flicking.

As a result of the CFF experiment according to the luminance, the CFF value decreases as the luminance decreases. In other words, the flicker on the dark screen becomes less recognizable.

Another characteristic of flicker is that the CFF of the chromatic flicker is reduced by about half compared to the luminance flicker.

11 is a diagram for explaining the concept of a luminance flicker and a color flicker. As shown in FIG. 11, the upper diagram shows a flicker in which the black and white states are temporally repeated. On the other hand, red and green appear repeatedly at the bottom. The average color represented by the time average is the same in both cases. However, when the frequency of repetition is the same, the level of flicker perceived by a person is strongly admitted twice in the upper case. People respond sensitively to the flicker of brightness.

The two phenomena described above (ie, the brighter the brighter the luminance, and the better the visibility of the luminance flicker than the color flicker), is not only a temporal flickering phenomenon, but also a spatial resolution capability . In other words, when there are spatially dark and bright lines repeatedly, the higher the average luminance, the higher the visible resolution, and the luminance contrast is better distinguished than the color contrast.

Therefore, in order to minimize the flickering phenomenon and the resolution degradation in implementing the two-frame mixing method, the following criteria are required.

i) Mixing algorithm should be applied with low gradation.

ii) Algorithm should be made mainly for B pixel and R pixel. Because, in white, the luminance ratio of R, G, B is approximately 21: 72: 7. The luminance of the B pixel and the R pixel is relatively low.

iii) induce chromatic modulation rather than luminance modulation.

According to an embodiment of the present invention, a method of implementing two-frame mixing under the above conditions can be embodied as follows.

i) In the case of the B pixel, the luminance modulation width is not large even if it is modulated to the full gray level or the high gray level. Thus, the B image data mixes two frames up to about 200 gigas up to high grayscale. In the case of the R pixel, since the luminance is much higher than the B data, the two frame mixing should be performed in the gradation region lower than the B image data. In case of the G pixel, since the luminance is the highest, the two frame mixing is not applied or only the very dark gradation is applied. Therefore, if the maximum gradations for mixing two frames of R, G, and B pixels are Rm, Gm, and Bm, 0 to Gm << Rm ≤ Bm.

ii) Thus, the actual two-frame mixing is performed in R and B pixels. In this case, the two-frame mixing of the B pixel and the two-frame mixing of the R pixel must be performed in order to make the minimum flickering condition described above. This is shown in Figs. 12A to 12C.

FIG. 12A is a graph in which regions are divided by the characteristics according to the up / down frame gradation of the B pixel, and FIG. 12B is a graph in which regions are classified through the characteristics according to the up / down frame gradation with respect to the target gradation of the G pixel. And FIG. 12C is a graph in which regions are divided by the characteristics according to the up / down frame gradation with respect to the target gradation of the R pixel.

12A to 12C, the horizontal axis denotes a target gray level, and the vertical axis denotes an up frame (the up frame means a frame signal including a bright gray) and a down frame (a down frame) Here, the down frame means a display gradation of a frame signal including a dark gradation). The B pixel shows the gradation difference between the up and down frames in the 0 to 200 gradation, the R pixel shows the gradation difference between the up and down frames in the 0 to 160 gradation, and the G pixel shows the gradation difference The gradation is displayed as it is. This means Bm = 200, Rm = 160, and Gm = 0. Therefore, the B pixel and R pixel gradation separation are largely divided into three regions. 12A to 12C are L / M / H regions.

 - H area: gray> Rm or Bm, two frame area without mixing.

 - M area: an area where the gradation of the down frame mainly changes,

이고, 업 프레임 계조는

이다. At this time, the down frame gradation of the B pixel is

, And the up frame gradation is

to be.

Here, G _i , G _{dn - blue} , G _{up - blue} represent the input gradation and the down / up gradation, and g represents the gamma value of the gradation curve. R pixel and latitude can be found the same way through the same equation.

- L area: an area where the gradation of the up frame mainly changes,

로 나타낼 수 있다. Taking the B pixel as an example, the down frame gradation is all 0, and the up frame gradation is

.

It is desirable to shift from the above equations to a continuous function so as not to lose the continuity of the image at the boundary of each region.

In actual two-frame mixing, when the B pixel of the first pixel is adjacent to the R pixel of the next pixel, R and B among the first R, G and B data display the down frame gradation in the first frame, Frame to display the up-frame gradation. At this time, since the neighboring pixels are reversed, the luminance flicking is compensated between adjacent pixels to induce a chromatic flicker.

The two-frame mixing method of the two-frame mixing unit 910 as described above can not improve the side viewability of the VA-LCD alone. On the other hand, when the two methods are used in combination with the time division method using the subframe in the subframe time division unit 920 described above, the degree of visibility can be applied to the actual product. Therefore, it is necessary to effectively combine the subframe time division technique and the two-frame mixing method in an actual product.

FIG. 13 is a detailed block diagram illustrating a two-frame mixing unit 910 according to an exemplary embodiment of the present invention. Referring to FIG. 13, a two-frame mixing unit 910 according to an embodiment of the present invention includes a frame count unit 1310, a pixel classifying unit 1320, an area classifying unit 1330, and a signal assigning unit 1340 ).

Referring to FIG. 13, it can be seen how the two-frame mixing is implemented in the two-frame mixing unit 910, which is a component of the present invention. The frame counting unit 1310 divides an input frame into an even-numbered frame and an odd-numbered frame. This is because the two-frame mixing occurs in consecutive frames, so that it is an even or odd frame to separate into consecutive frames.

The pixel division unit 1320 divides pixels according to the color of each pixel of the input frame. That is, it can be discriminated whether it is an R pixel, a G pixel, or a B pixel. Each pixel has different two-frame mixing characteristics depending on the color, so it distinguishes it. Here, the pixels classified by the G pixels are not subjected to two-frame mixing, or the two-frame mixing is performed only for dark gradations.

The region dividing unit 1330 divides the pixel region into the H region, the M region, and the L region, based on the gradation level of the pixel, And the pixels belonging to the pixel belonging to the same are divided and classified. Since the formulas for finding the up / down frames are different for each area, the region dividing unit 1330 divides the regions according to the color characteristics of each pixel.

The signal assignment unit 1340 outputs the up frame gray level signal and the down frame gray level signal to the pixels belonging to the specific region of each color separated in the region division unit 1330 using the up frame / Signal. At this time, if an up-frame gradation signal is given to an even-numbered frame, a down-frame gradation signal must be given to a corresponding pixel of an odd-numbered frame adjacent to the even-numbered frame. This may be the opposite case.

Depending on the case, the signal assigning unit 1340 may give the up frame gradation if i + j is an even number for the (i, j) th pixel in the even frame, and give the down frame gradation if it is an odd number. Further, in the odd frame, if the (i, j) th pixel is an even number, the down frame gradation is given, and if it is an odd number, the up frame gradation can be given. However, the present invention is not limited thereto.

The thus transformed signal is transmitted to the LCD panel through the time division logic of the subframe time division unit 920. [

Fast Frame Algorithm

FIG. 14 is a block diagram illustrating an interlocking relationship between a fast frame algorithm application unit and a subframe time division unit in a liquid crystal display device according to an embodiment of the present invention. Referring to FIG. As shown in FIG. 14, the fast frame algorithm application unit 1410 can be combined with the subframe time division unit 1420 as a preprocessing process.

Referring to FIG. 14, the fast frame algorithm application unit 1410 improves the motion picture characteristic by using a high-speed frame driving method. The fast frame algorithm application unit 1410 performs interpolation on an input frame to generate four fast sub-frames, It is possible to determine the characteristics of the frame and determine whether to perform the time division operation in the subframe time division unit 1420. [ Also, when performing a time division operation, it is possible to determine which subframe is output first.

The subframe time division unit 1420 determines whether or not time division is to be performed based on the signal related to the time division execution of the fast frame algorithm application unit 1410 as described above, And determines a sub-frame-by-sub-frame implementation method to apply a signal to each pixel.

With respect to the high-speed frame algorithm, the LCD displays the same picture signal until the next frame after the picture signal is displayed. This type of display is called a holding type display and is distinguished from an impulsive type display in which light is radiated only when an electron beam collides with a phosphor such as a CRT. The holding type display has a problem that the boundaries of the moving objects are blurred because one image lasts for one frame in the moving image driving. To solve this problem, one of two techniques is usually applied. The two technologies are impulsive driving technology that imitates impulsive type, and high-speed frame driving technology that generates and inserts an interpolated image in the middle of 120 Hz or 240 Hz high-speed frame driving.

Generally, in VA-LCD, techniques for improving moving picture characteristics by a high-speed frame driving method are frequently used. The image data input at 60 Hz is converted into 240 Hz and output. At this time, each frame is divided into four high-speed sub-frames, and the newly added three frames are composed of interpolated images. Therefore, although the high-speed frame driving method is similar to the sub-frame time division technique, the former forms a sub-frame with the interpolated images, while the latter displays the bright image and the dark image alternately. The effect will not be generated. Therefore, logic that can improve the side viewability and motion picture simultaneously is needed.

It is necessary to examine the response waveform of an actual panel when the subframe time division method is applied to the subframe time division unit 1420. [ Experimental results show that when the subframes a and b appear, the luminance varies across black and white. This is almost the same driving method as the actual impulsive driving method.

The subframes a and b take approximately 0 to 200 gradation areas. Therefore, it is not necessary to apply a high-speed frame driving technique to an image in the range of 0 to 200 gradations. Some impulsive driving functions are applied in the remaining 200 to 255 gradation regions, but the effect becomes weaker as the gradation increases. Therefore, it may be desirable to apply a high-speed frame driving technique in a high gray level in order to exhibit a perfect high-speed response characteristic.

Two approaches can be used for this purpose.

15 is a flowchart illustrating an operation of a fast frame algorithm according to an embodiment of the present invention. Referring to FIG. 15, an input image is compared with a next frame signal and divided into four high-speed sub-frames through interpolation (S1510). That is, three interpolation signals are generated in the middle, and four data Gi, G1, G2, and G3 are generated for each pixel (S1520). It is determined whether the signal is a high-speed frame signal based on the generated signal (S1530). If it is determined that the generated four signals have substantially no change, it is determined that the generated four signals correspond to the still image, and the signal is transmitted to the subframe time division unit 1420 without applying the fast frame algorithm to perform the time division operation (S1540). If it is judged that the generated four signals are considerably changed to be video signals, it is judged whether the gradation of 200 Gray or more is included in the signal (S1550). If there is no signal having 200 gradations or more, the signal is transmitted to the subframe time division unit 1420 to perform the subframe time division operation (S1540). If there is a 200-gradation or higher signal, the subframe time division operation is immediately performed without outputting to the panel (S1560).

In other words, a pixel including more than 200 gradations in four high-speed sub-frame gradations for each pixel outputs a result through a high-speed frame algorithm, and the remaining pixels are transmitted to a sub-frame time- And displays it.

For a video signal to be directly output without being transmitted to the subframe time division unit 1420, a moving picture signal, that is, a video signal in which the gradation is abruptly changed, is included in an actual high-speed frame signal, so that a certain time- . Therefore, even if the sub-frame time division is not performed, side viewability is improved to some extent.

16 is a flowchart illustrating an operation of the fast frame algorithm according to another embodiment of the present invention. Unlike the embodiment described in FIG. 15, a fast frame algorithm can be applied so that the subframe technique is always applied.

Referring to FIG. 16, as in the embodiment of FIG. 15, a high-speed frame algorithm is performed first. In other words, the input image is compared with the next frame signal and separated into four high-speed subframes through interpolation (S1610). Three interpolation signals are generated in the middle, and four data Gi, G1, G2 and G3 (Step S1620). In operation S1630, the subframe a, b, c, and d are generated by performing a time division operation in the subframe time division unit 1420 based on the average luminance of the generated Gi, G1, G2, and G3 signals. Next, it is analyzed which position among the Gi, G1, G2 and G3 signals the highest luminance is distributed (S1640). The subframe a -> b -> c ->G1>G2> G3 is satisfied if Gi>G1>G2> G3 or Gi <G1 <G2 <G3. d are output in order. On the other hand, when Gi <G1 <G2 <G3 (S1655), the output is performed in the reverse order as d -> c -> b -> a. The high-speed frame algorithm application unit 1410 may adjust the order of the subframes so as to be output so as to be output in the same direction as the luminance change direction.

3D Stereoscopic

Time-division stereoscopic 3D technology also divides a 1-frame signal into 4 frames, the former two frames are used for the left eye, and the latter two frames are used for the right eye. Therefore, the subframe time division technique can not be applied while the 3D image is displayed.

In this case, the two-frame mixing method described above can be used in combination with 3D technology. The two frame mixing algorithm can be used to modify both the left eye and right eye images before outputting to the display via 3D signal processing.

Limit of response speed

It can be seen that the lateral visibility of the VA LCD is sensitive to the response speed of the liquid crystal. This can be proved experimentally.

17 is a graph showing the relationship between the liquid crystal response speed and the visual perception. As shown in FIG. 17, the visibility level is proportional to the response speed. The table below shows the following.

As shown in Table 1, the larger the frequency of the signal, the slower the response speed, and thus the worse the side visibility.

Therefore, the response speed (on + off) of the liquid crystal should be lower than 10.0 msec on the basis of the driving condition of 240 Hz in order to obtain the visibility more than similar characteristics compared to the existing pixel division structure. In particular, in order to obtain optimized panel-level characteristics among existing pixel division technologies, the sum of the black-white reference response speeds should be less than 8 msec.

Since the influence of the response speed of the liquid crystal on the visibility of the time division technique is very large, it is necessary to identify the cause of the delay in the response speed of the LCD and to improve it. The reason is that the voltage applied to the pixel decreases due to a change in the capacitance of the liquid crystal.

18 is a view for explaining a relationship between a voltage and a capacitance in a TFT and a pixel of a panel of a liquid crystal display device according to an embodiment of the present invention. As shown in FIG. 8, a data line DL and a gate line GL are connected to a TFT, and a liquid crystal cell of one pixel is connected to the data line DL and the gate line GL. As described above, the liquid crystal cell of the pixel may include a region in which two liquid crystal response speeds are different. Though not shown in the figure, other switching elements other than TFTs may be used, and are not necessarily limited to TFTs.

Referring to FIG. 18, the liquid crystal display device supplies an analog image signal, which is analog-converted based on the gamma reference voltage, to the data line DL and simultaneously supplies a scan pulse to the gate line GL, ).

The gate electrode of the TFT is connected to the gate line GL and the source electrode thereof is connected to the data line DL while the drain electrode of the TFT is connected to the pixel electrode of the liquid crystal cell Clc of the pixel and one electrode of the storage capacitor Cst Respectively. The common voltage Vcom can be supplied to the common electrode of the liquid crystal cell Clc of the pixel. The storage capacitor Cst charges the data voltage applied from the data line DL to keep the voltage of the liquid crystal cell Clc of the pixel constant when the TFT is turned on.

At this time, in order to overcome the aforementioned pixel application voltage reduction phenomenon, the black voltage and the white voltage of the liquid crystal cell Clc connected to the TFT may be controlled or the ratio of the dielectric constant of the liquid crystal may be limited.

If e_e and e_o are the long axis and short axis direction dielectric constant of a liquid crystal director, when switching from black to white, when the liquid crystal is initially standing vertically, a high voltage (Vi) The liquid crystal is rotated in the horizontal direction by the voltage. At this time, the average dielectric constant of the initial liquid crystal cell Clc is e_e, but the average dielectric constant gradually moves toward e_o as the liquid crystal rotates. Assuming that the dielectric constant after the liquid crystal is rotated is e_eff, the voltage (Vf) finally applied to the pixel is as follows.

Where Ci and Cf are the initial and final pixel capacitances, Cst is the storage capacitance, C _{LC -i} and C _{LC -f} are the initial and final liquid crystal capacitances. In the VA LCD, e_e / e_eff is smaller than 1 and has a value close to 1/2, so that a voltage drop occurs.

On the other hand, when changing from white to black, the voltage (e_eff / e_e) is applied instead of (e_e / e_eff)

According to an embodiment of the present invention, in order to overcome the above-mentioned phenomenon, the following restrictions are put.

1) First, apply 0 gray voltage when coming from white to black. At this time, when a high voltage is applied based on the common gray voltage Vcom (the common voltage may be a voltage applied to the top electrode), the voltage finally applied to the pixel is initially applied A voltage which is twice as high as the quasi-voltage is applied, which slows off the response speed. To overcome this, it is preferable to apply a voltage close to zero to Vi. This improves the off-response speed of the liquid crystal to improve lateral visibility. At this time, since Vi is the reference voltage of the common voltage (Vcom), | Vi-Vcom | The smaller the value, the better. However, since the common voltage Vcom has different values for each panel position, it is difficult to make | Vi-Vcom | completely 0 volts. In conventional LCDs, the 0 gray voltage is adjusted to about 1.0 to 1.7 volts. However, when the voltage is doubled, it is 2.0 to 3.4, which is the voltage that the liquid crystal can not go to black. (Approximately Vth of 2.0 volts)

Therefore, | V (0 gray) - Vcom | A level of < 0.7 volts is preferred. The most preferred is | V (0 gray) - Vcom | &Lt; 0.3 Volt.

2) The second method is to increase the liquid crystal property (e_e / e_o) ratio in order to increase the liquid crystal response speed when changing from black to white. Typical VA LC has a value of (e_e / e_o) = (3.3 / 6.8) ≡ 0.5. However, by changing to (e_e / e_o) = (3.8 / 6.2) ≡ 0.6, the voltage drop can be improved by about 25%. Therefore, it is preferable to use a low dielectric constant anisotropic liquid crystal having (e_e / e_o)> 0.6.

3) The third method is to increase the white voltage. Increasing the white voltage in the time division method can compensate for the increased voltage even if the voltage drop occurs. Therefore, it is advantageous to use a high voltage drive method, Vmax - Vcom> 7 volts, in the time division method.

According to the embodiment of the present invention, side viewability can be improved by using the method of increasing the LCD response speed and the subframe time division scheme in combination. That is, in addition to the signal control for the subframe time division mode, the controller 110 can perform voltage control for increasing the LCD response speed, and at this time, by using anisotropic liquid crystal having a low dielectric constant in addition to the liquid crystal, Can be maximized.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions as defined by the following claims It will be understood that various modifications and changes may be made thereto without departing from the spirit and scope of the invention.

Claims (28)

A time division display method in a display apparatus for converting and displaying an input image frame into a plurality of subframes f1, f2, f3, ... fn so that an image can be displayed at a frequency higher than the frame frequency of the input image signal. To
A plurality of image signals having different luminance from an input image signal for each pixel among the pixels constituting the input frame, wherein an average of the luminance of the plurality of image signals is substantially the same as the luminance of the input image signal; Generating them Sa1;
Determining a gray level for each subframe based on the gray levels of the plurality of image signals of each of the generated pixels, wherein the number of the generated image signals and the number of the subframes correspond to each other (Sa2);
Generating a plurality of subframes based on the gray level of the determined subframe and the generated plurality of image signals (Sa3); And
Displaying the generated sub-frame (Sa4),
The gradation applied to the subframe is a combination of up to three gradations including substantially black gradation (gradation near 0 or 0), substantially white gradation (gradation near 255 or 255), and variable intermediate gradation (M). Time division display method characterized in that consisting of.
The method of claim 1,
The order of the gray level of the sub-frame is a time division display method, characterized in that the order from the dark to the light gray, the order from the light gray to the dark gray, or the order of the two orders are cycled.
The method of claim 1, wherein the gray level determination step (Sa2)
And determining the intermediate gray scale (M) by measuring an average luminance appearing while changing the gray scale of the sub-frame.
The method of claim 1, wherein the gray level determination step (Sa2)
And determining the normalized gray level value corresponding to the gray level values of the plurality of image signals of each pixel of the subframe as the gray level of the subframe.
The method of claim 1,
Generating four subframes by time-sharing the input frame,
Further comprising dividing the subframe into four regions (a low gradation region, a relay gradation region, a high gradation region, and a highest gradation region) according to a gradation level of a plurality of video signals of each pixel, Display method.
The method of claim 1, wherein the subframe generation step Sa3
(a) Low gradation regions (0 to 255,0,0,0)-Low gradation regions (a, b, c, d) are for pixels belonging to the low gradation region, where a is a first subframe and b is a 2 subframes, c is a third subframe, d is a fourth subframe, 0 to 255 is a section that is varied according to the corresponding gray level according to the gray level of the input image, 0 is a gray level of 0 255 means to implement a gradation value of 255 or gradation close to 255, gradation region (255,0 ~ 255,0,0), high gradation region (255,255,0 ~) 255,0) and the highest gray scale region 255, 255, 255, 0 to 255;
(b) Low gradation area (0 ~ 255, 0 ~ 255, 0, 0), high gradation area (255, 255, 0 ~ 255, 0), highest gradation area (255, 255, 255, 0 ~ 255) Way to implement;
(c) Low gradation area (0 ~ 255, 0, 0, 0), used gradation area (255, 0 ~ 255, 0 ~ 255, 0), highest gradation area (255, 255, 255, 0 ~ 255) How to implement;
(d) Low gradation area (0 ~ 255, 0, 0, 0), gradation area (255, 0 ~ 255, 0, 0), high-high gradation area (255, 255, 0 ~ 255, 0 ~ 255 To implement; And
(e) a method implemented on all subframes (0 to 255, 0 to 255, 0 to 255, and 0 to 255) for all gray areas; Selecting at least one of the subframes to generate the subframes.
The method of claim 1,
The method may further include applying a high speed frame algorithm to the input frame before the image signal generating step Sa1.
The fast frame algorithm application step,
Splitting into four high-speed subframes by performing interpolation based on consecutive input frames;
Calculating a signal change amount between the high speed subframes; And
And if the amount of change is large, performing a frame algorithm, and if the amount of small change is small, skipping to the image signal generation step (Sa1) without performing the frame algorithm.
8. The method of claim 7, wherein the frame algorithm is
Determining whether a pixel of the high speed subframe includes more than 200 gray levels; And
And the pixel which does not include the gray level of 200 gray or more is directly skipped to the image signal generating step Sa1, and directly displaying the pixel including the gray level of 200 gray or more without applying a change. Time division display method.
The method of claim 7, wherein
Before the image signal generation step (Sa1), further comprising the step of applying a high-speed frame algorithm to the input frame,
The fast frame algorithm application step
Splitting into four high-speed subframes by performing interpolation based on consecutive input frames;
Generating a signal applied to each pixel of the subframe generated by performing the image signal generating step Sa1 to the subframe generating step Sa3 based on the average luminance of the fast subframe; And
And adjusting the order of the generated subframes so that a subframe having the highest gray level is first output based on a plurality of image signals of each pixel of the subframe.
In a time division display method for displaying an image at a frequency higher than a frame frequency of an input video signal,
A dithering step (Sb1) of image-processing the input image frame so as to be dithered with at least one adjacent pixels having a similar luminance, with an average luminance equal to an average luminance of an input image frame;
A mixing step (Sb2) for mixing the consecutive two frame luminance by exchanging the darkness and brightness of the pixel in the next frame with respect to the video signal of the dithering pixel;
And generating a plurality of subframes (Sb3) by dividing the mixed frame based on the gradation of the subframe determined for each pixel.
11. The method of claim 10,
Wherein the subframe generation step includes generating a subframe image signal so that the subframe image signal is displayed at three gradation levels of a dark gradation, a light gradation, and a middle gradation.
The method of claim 10, wherein the mixing step (Sb2)
Dividing the input frame into an even-numbered frame and an odd-numbered frame; And
Frame gray scale signal that is a frame signal including a bright gradation is given to one pixel and a gray-scale signal is included in the other pixel for the pixels of the odd-numbered frame and the corresponding pixels of the odd- And providing a down frame gradation signal that is a frame signal to be supplied to the time division display method.
The method of claim 12, wherein the step of applying the gray level signal
Frame to the (i, j) -th pixel of the odd-numbered frame, the up-frame gradation signal is given if i + j is an odd number, and the down-frame gradation signal is given if i + j is an even number,
(I, j) -th pixel of the even-numbered frame, if the (i + j) th pixel is an odd-numbered pixel, and if i + j is an even-numbered pixel, Time display method.
The method of claim 12, wherein the step of applying the gray level signal
Dividing the input frame according to the color of each pixel;
The gray level of the B or R pixel is Rm (the maximum gradation value of the R pixel) or Bm (the maximum gradation value of the R pixel) when the pixel is the G pixel and the mixing step Sb2 is not performed, The highest gray level value of the B pixel), the M region where the gradation of the down frame mainly changes, and the G region where the gradation of the up frame mainly changes. And
The pixel belonging to the H region does not perform the mixing step Sb2 with respect to the divided region and the pixels belonging to the M and G regions are given different types of up frame gray level signals and down frame gray level signals Wherein the time-divisional display method comprises the steps of:
A time-division display method capable of displaying an image at a frequency higher than a frame frequency of an input video signal,
Providing a plurality of sub-frame gradation division schemes through a plurality of pre-input lookup tables or image conversion logic based on the gradations of the pixels of the input image signal;
(Sc2) analyzing a relative size of the R, G, and B gradation levels corresponding to each pixel of the input image signal; And
(Sc3) applying different sub-frame division schemes among the plurality of sub-frame gradation division schemes to the R, G, and B pixels according to the analyzed relative sizes of the R, G, and B gradations / RTI &gt;
The method of claim 15, wherein the applying of the subframe division scheme Sc3 is performed.
As a result of the size analysis, a dividing scheme having a low value of a side gamma curve is applied to a first color pixel having the lowest gradation value, and a side gamma curve has a high value for a pixel having a color other than the first color And applying a dithering method in which a method of using the image data is appropriately mixed.
The method of claim 15, wherein the applying of the subframe division scheme Sc3 is performed.
The plurality of grayscales corresponding to the sub-frames of each pixel are input to an image frame including a substantially black grayscale (zero or close to zero), a substantially white grayscale (gray or near to 255), and a variable intermediate grayscale (M). Dividing the into a plurality of subframes,
The input frame is divided such that the number of subframes displayed as the middle grayscale M among the plurality of grayscales is 1 to n, and the middle grayscale M is an average luminance appearing while changing the grayscale of the subframe. Time division display method characterized in that determined by measuring.
The method of claim 15,
Generating four subframes by time-sharing the input frame,
Further comprising dividing the subframe into four regions (a low gradation region, a relay gradation region, a high gradation region, and a highest gradation region) according to a gradation level of a plurality of video signals of each pixel, Display method.
The method of claim 15, wherein the plurality of subframe gray level division schemes
(a) Low gradation regions (0 to 255,0,0,0)-Low gradation regions (a, b, c, d) are for pixels belonging to the low gradation region, where a is a first subframe and b is a 2 subframes, c is a third subframe, d is a fourth subframe, 0 to 255 is a section that is varied according to the corresponding gray level according to the gray level of the input image, 0 is a gray level of 0 255 means to implement a gradation value of 255 or gradation close to 255, gradation region (255,0 ~ 255,0,0), high gradation region (255,255,0 ~) 255, 0) and the highest gradation region 255, 255, 255, 0 to 255;
255, 0, 255, 0, 255), the highest gradation region (255, 255, 255, 0 to 255) ;
(c) The gradation range (0 to 255, 0, 0, 0), the used gradation range (255, 0 to 255, 0 to 255, 0) and the highest gradation range (255, 255, 255, 0 to 255) Split method;
0 to 255, 0 to 255, 0 to 255, 0 to 255, 0 to 255, 0 to 255, and 0 to 255 in the high gradation range (d) ); And
(e) a method of dividing the entire gradation area so as to be displayed on all subframes (0 to 255, 0 to 255, 0 to 255, and 0 to 255).
20. The method of claim 19, wherein applying the subframe division scheme Sc3 is performed.
As a result of the size analysis, if the method of (a) is applied to a pixel of the first color having the lowest gray-scale value and the color of the pixel of the sub-frame is the second color, (B), (c), (d), and (e) for the number of the adjacent pixels proportional to the difference between the gray-level values of the pixels of the second color and the gray- The method comprising the steps of:
Time-dividing the input image frame into a plurality of subframes and dividing an image signal for each subframe; And
A display step of displaying an image based on the divided image signal,
And a response speed (Ton + Toff) of the liquid crystal between the black image and the white image of each pixel of the panel displaying the image has a value smaller than 10 msec.
A liquid crystal display device which converts and displays an input image frame into a plurality of subframes (f1, f2, f3, ... fn) so that an image can be displayed at a frequency higher than the frame frequency of the input image signal.
A plurality of image signals having different luminance from an input image signal for each pixel among the pixels constituting the input frame, wherein an average of the luminance of the plurality of image signals is substantially the same as the luminance of the input image signal; An image signal generation unit for generating sound;
A gray scale determination unit configured to determine a gray scale for each subframe based on the gray scales of the plurality of image signals of each of the generated pixels, wherein the number of the generated image signals and the number of the subframes correspond to each other;
A subframe generation unit configured to generate a plurality of subframes based on the gray level of the determined subframe and the generated plurality of image signals; And
Including a display unit for displaying the generated sub-frame,
The gradation applied to the subframe is a combination of up to three gradations including substantially black gradation (gradation near 0 or 0), substantially white gradation (gradation near 255 or 255), and variable intermediate gradation (M). Liquid crystal display device, characterized in that consisting of.
1. A liquid crystal display device for displaying an image at a frequency higher than a frame frequency of an input video signal,
A dithering unit having an average luminance equal to an average luminance of an input image frame and performing image processing so that the input image frame is dithered with at least one adjacent pixels having a similar luminance;
A mixing unit for mixing the consecutive two frame luminance by exchanging the darkness and brightness of the pixel in the next frame with respect to the video signal of the dithering pixel;
And a subframe generator for generating a plurality of subframes by dividing the mixed frame based on the gray level of the subframe determined for each pixel.
1. A liquid crystal display device capable of displaying an image at a frequency higher than a frame frequency of an input video signal,
A driving circuit for providing the plurality of sub-frame gradation division schemes through a plurality of pre-input lookup tables or image conversion logic based on the gradation of each pixel of the input image signal;
A gradation level analyzer for analyzing relative sizes of R, G and B gradation levels corresponding to each pixel of the input image signal; And
And a sub-frame dividing method applying unit for applying different sub-frame dividing methods among R, G, and B pixels among the plurality of gradation division methods (functions) of the plurality of sub-frames according to the analyzed relative sizes of R, And the liquid crystal display device.
A time division unit for time-dividing an input image frame into a plurality of sub frames and dividing an image signal for each sub frame; And
A display unit for displaying an image based on the divided image signal,
And a response speed (Ton + Toff) of the liquid crystal between the black image and the white image of each pixel of the panel of the display unit is smaller than 10 msec.
The method of claim 25,
_Wherein a difference between a 0 gray voltage (V 0 gray) and a common voltage (Vcom) of a TFT (Thin Film Transistor) of the panel is smaller than 0.7 volts.
The method of claim 25,
Wherein the pixels of the panel are made of anisotropic liquid crystal with a low dielectric constant having a ratio of a dielectric constant in a major axis and a minor axis direction of a liquid crystal director is 0.6.
The method of claim 25,
And a white voltage (Vmax) of the TFT of the panel is greater than 7 volts greater than the common voltage (Vcom).

Images