KR20090008061A - LCD Display - Google Patents

Abstract

The present invention relates to a liquid crystal display device capable of minimizing motion blur in a sequential driving method.

A liquid crystal display device which is driven by dividing one frame period into k (integers of two or more) subframe periods, comprising: a liquid crystal display panel on which an image is displayed; A data driver supplying a data voltage to the liquid crystal display panel; A gate driver supplying scan pulses to the liquid crystal display panel; Modulates the input data, divides the interval k between the first subframe data position of the nth frame data and the first subframe data position of the n + 1th frame data, and specifies the position of each subframe data of the nth frame An output data modulator; And converting the driving frequency of the input data by k times, and synchronizing with the converted driving frequency to specify driving timings of the subframe data of the n-th frame data positioned in the data modulator, thereby driving the data driver and the gate. A timing controller for controlling the driving unit is provided.

Description

Liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display capable of minimizing motion blur in a sequential driving method.

In general, the liquid crystal display device has a trend that the application range is gradually widened due to the characteristics such as light weight, thin, low power consumption. In accordance with this trend, liquid crystal displays are used in office automation equipment, audio / video equipment, and the like. In such a liquid crystal display, a transmission amount of a light beam is adjusted according to a signal applied to a plurality of control switches arranged in a matrix to display a desired image on a screen. To this end, the liquid crystal display includes a liquid crystal display panel in which liquid crystal cells are arranged in a matrix, and a driving unit for driving the liquid crystal display panel.

The liquid crystal display panel is formed by bonding a thin film transistor array substrate on which a thin film transistor array is formed and a color filter array substrate on which a color filter array is formed, with the liquid crystal layer interposed therebetween.

Data lines and gate lines that are orthogonal to each other are formed on the thin film transistor array substrate, and liquid crystal cells are formed in each region formed by the orthogonality of the data lines and the gate lines. The thin film transistor connected to the intersection of the data lines and the gate lines supplies the data supplied through the data line to the pixel of the liquid crystal cell in response to the scan pulse of the gate line.

A black matrix, a color filter, and the like are formed on the color filter array substrate.

The driver includes a data driver and a gate driver. The data driver supplies data to the data lines, and the gate driver supplies scan pulses to the gate lines.

Since the liquid crystal display is not a self-luminous display, a separate backlight is required. Types of backlight include Cold Cathode Flourscent Lamps (CCFLs), External Electrode Flourscent Lamps (EEFLs), and Light Emitting Diodes (LEDs). The backlight generates white light, and irradiates white light to liquid crystal cells to which red, green, and blue data are simultaneously applied through the thin film transistor turned on by the scan pulse. As a result, the white light irradiated to the liquid crystal cell is irradiated to the red, green, and blue color filters with luminance according to the data applied to each liquid crystal cell, and is changed into red, green, and blue light, respectively. The liquid crystal display panel displays a desired color by combining red, green and blue light.

A general liquid crystal display having such a configuration has a disadvantage in that light is lost while passing through the color filter due to light absorption of the color filter, and thus the luminance is low, and the color purity is low by the color filter. In addition, when the LCD is driven as a hold type that keeps the backlight on, power consumption is large because the backlights must be kept on. In order to solve the above disadvantages, a liquid crystal display device having a sequential driving method such as a field sequential method has been proposed.

In the field sequential liquid crystal display, the red light source, the green light source, and the blue light source are sequentially driven instead of the color filter by color. That is, a red light source is turned on when red data is applied to the liquid crystal cell, a green light source is turned on when green data is applied to the liquid crystal cell, and a blue light source is turned on when blue data is applied to the liquid crystal cell.

FIG. 1 illustrates a method of displaying a moving image in which a white band-shaped data as shown in FIG. 2 is moved in the A direction in a field sequential liquid crystal display.

Referring to FIG. 1, in a field sequential liquid crystal display, red, green, and blue light sources are sequentially turned on to display white images, and then red, green, and blue data are sequentially displayed within one frame period as subframe data. Done. In this case, the red, green, and blue data are sequentially displayed at the same position in the liquid crystal display panel during the same frame period, so that they appear to be white bands. The red, green, and blue data are displayed by gradually moving in the A direction every frame period.

The data of the stationary white band which is moved and displayed every frame period is displayed as a moving picture of the white band moving in the A direction to the viewer's eyes. However, there is a problem that motion blurring occurs in the actual perceptual image due to the inconsistency between the eye movement and the static image of each frame, resulting in a blur region having color separation at both sides of the white band. have.

An object of the present invention to provide a liquid crystal display device that can minimize the motion blur in the sequential driving method.

In order to achieve the above object, a liquid crystal display device according to an embodiment of the present invention is a liquid crystal display panel in which an image is displayed in a liquid crystal display device driven by dividing one frame period into k (an integer of 2 or more) subframe periods. ; A data driver supplying a data voltage to the liquid crystal display panel; A gate driver supplying scan pulses to the liquid crystal display panel; Modulates the input data, divides the interval k between the first subframe data position of the nth frame data and the first subframe data position of the n + 1th frame data, and specifies the position of each subframe data of the nth frame An output data modulator; And converting the driving frequency of the input data by k times, and synchronizing with the converted driving frequency to specify driving timings of the subframe data of the n-th frame data positioned in the data modulator, thereby driving the data driver and the gate. A timing controller for controlling the driving unit is provided.

The data modulator may include a first frame memory configured to store and output the n-th frame data; A second frame memory for storing and outputting the n + 1 th frame data; Comparing the first subframe data position of the nth frame data supplied from the first frame memory with the first subframe data position of the n + 1th frame data supplied from the second frame memory, wherein the nth Divide the interval between the first subframe data position of the frame data and the first subframe data position of the n + 1th frame data by k, and determine the second to kth subframe data positions of the nth frame data by An arithmetic unit for designating and outputting each of 1 / k to (k-1) / k points from the first subframe data position of the second frame data; And k-1 third frame memories respectively storing second to kth subframe data of the nth frame data supplied from the calculator and supplying the second to kth subframe data to the timing controller, wherein the first frame memory is the nth frame. The first subframe data of the frame data is supplied to the timing controller.

The data modulator may include a first frame memory configured to store and output the n-th frame data; A second frame memory for storing and outputting the n + 1 th frame data; a third frame memory for storing and outputting n + 2th frame data; And comparing the first subframe data position of the n th frame data supplied from the first frame memory with the first subframe data position of the n + 1 th frame data supplied from the second frame memory, wherein n K equally divides an interval between a first subframe data position of the first frame data and a first subframe data position of the n + 1th frame data, and recalls a second to kth subframe data position of the nth frame data; The n + 1 th frame supplied from the second frame memory and supplied to the timing controller by designating 1 / k to (k-1) / k points from the first subframe data position of the n th frame data, respectively. First subframe data position of data and the n + 2 th frame supplied from the third frame memory Comparing the first subframe data position of the data, dividing k by an equal interval between the first subframe data position of the n + 1th frame data and the first subframe data position of the n + 2th frame data, and The timing is determined by designating the second to k th subframe data positions of the n + 1 th frame data as 1 / k to (k-1) / k points from the first subframe data position of the n + 1 th frame data, respectively. It has a calculating part for supplying to a controller.

In the liquid crystal display according to the exemplary embodiment of the present invention, the motion blur phenomenon may be minimized by differently specifying the position of the subframe data in each subframe in the sequential driving method.

Other objects and advantages of the present invention in addition to the above object will be apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 3 to 5.

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

Referring to FIG. 3, a liquid crystal display according to an exemplary embodiment of the present invention is a field sequential liquid crystal display, and includes a data modulator 2, a timing controller 4, a data driver 6, and a modulator for input data. A gate driver 8, a liquid crystal display panel 10, and a backlight 12 are provided.

The liquid crystal display panel 10 includes an upper substrate and a lower substrate bonded to each other with a liquid crystal layer interposed therebetween.

The data lines DL and the gate lines GL formed on the lower substrate of the liquid crystal display panel 10 are perpendicular to each other. A thin film transistor (TFT) connected to an intersection of the data lines DL and the gate lines GL has a data voltage supplied through the data line DL in response to a scan pulse of the gate line GL. Is supplied to the pixel electrode Ep of the liquid crystal cell.

The liquid crystal mode of the liquid crystal display panel 10 is a liquid crystal mode of a horizontal electric field driving method such as an in plane switching (IPS) mode, a fringe field switching (FFS) mode, or a vertical such as a twisted nematic (TN) mode or a vertical alignment (VA) mode. It is roughly divided into the liquid crystal mode of the electric field driving system.

When the liquid crystal display panel 10 is a horizontal electric field driving method, a common electrode Ec is further formed on the lower substrate. The liquid crystal capacitor Clc is formed in the liquid crystal layer between the pixel electrode Ep and the common electrode Ec, and the potential difference between the data voltage supplied to the pixel electrode Ep and the common voltage supplied to the common electrode Ec. The liquid crystal having dielectric anisotropy is driven through the horizontal electric field to adjust the light transmittance according to the data voltage of the video data.

When the liquid crystal display panel 10 is a vertical electric field driving method, the common electrode Ec is formed on the upper substrate. The liquid crystal capacitor Clc is formed in the liquid crystal layer between the pixel electrode Ep and the common electrode Ec, and the data voltage supplied to the pixel electrode Ep and the common voltage supplied to the common electrode Ec located on the upper substrate. A liquid crystal having dielectric anisotropy is driven through a vertical electric field due to a potential difference between and to adjust light transmittance according to the data voltage of video data.

A polarizing plate having an optical axis orthogonal to each other is attached on the lower substrate and the upper substrate of the liquid crystal display panel 10, and an alignment layer for determining the pretilt angle of the liquid crystal is formed on the inner side of the liquid crystal layer in contact with the liquid crystal layer. In addition, a storage capacitor Cst is formed on the lower substrate of each liquid crystal cell. The storage capacitor Cst is formed between the pixel electrode Ep supplied with the data voltage and the storage electrode Est supplied with the storage voltage to maintain a constant data voltage charged in the liquid crystal cell.

The data driver 6 converts the input digital video data into an analog data voltage using a gamma voltage and supplies the analog data voltage to the data lines DL.

The gate driving circuit 8 sequentially supplies a scan pulse to the gate lines GL to select a horizontal line of the liquid crystal cell to which a data voltage is supplied. In other words, the gate driving circuit 8 turns on or off the TFTs connected to the respective gate lines GL by sequentially supplying scan pulses to the gate lines GL. The turned-on TFT conducts the data lines DL and the pixel electrode Ep so that the data voltage can be supplied to the pixel electrode Ep.

The backlight 12 irradiates light onto the liquid crystal display panel 10, and a light emitting diode (LED) may be used as the light source. The backlight 12 includes red, green, and blue light sources, and is sequentially turned on for one frame period.

Referring to FIG. 4, the data modulator 2 may include the first frame memory 14, the second frame memory 16, the calculator 18, the third frame memory 20, and the fourth frame memory 22. Equipped.

The first frame memory 14 stores n data of the nth frame and supplies the data to the operation unit 8, and the second frame memory 16 supplies data of the n + 1th frame (n + 1 data). It is stored and supplied to the calculating part 8. Data of the n th and n + 1 th frames (n data, n + 1 data) includes red, green, and blue data, respectively.

The calculation unit 18 receives the data of the nth frame (n data) and the data of the n + 1th frame (n + 1 data) and compares the positions of the two data. In the field sequential liquid crystal display device according to the exemplary embodiment of the present invention, red, green, and blue data are sequentially displayed. That is, red, green, and blue data included in one frame data are divided into three subframe data and displayed for each subframe. The calculation unit 18 compares the position of the first subframe data of the n th frame data (n data) with the position of the first subframe data of the n + 1 th frame data (n + 1 data). In addition, the operation unit 18 divides the first subframe data position of the n th frame data (n data) and the first subframe data position of the n + 1 th frame data (n + 1 data) into three equal parts, and n The second subframe data is positioned at a third point from the first subframe data position of the first frame data (n data) and supplied to the third frame memory 20, and the third subframe is located at a second third point. The position of the data is designated and supplied to the fourth frame memory 22.

The third frame memory 20 supplies the second subframe data (n2 data) of the n-th frame that is positioned to the timing controller 4, and the fourth frame memory 22 stores three of the n-th frame located. The first subframe data n3 data is supplied to the timing controller 4. In this case, the first subframe data n1 data of the nth frame is supplied from the first frame memory 14 to the timing controller 4.

The timing controller 4 converts the driving frequency to specify the driving timing of the subframe data, and controls the data driver 6 and the gate driver 8. In field sequential mode, the driving frequency is converted from 60Hz to 180Hz. At this time, the subframe data supplied from the data modulator 2 is supplied to the data driver 6 in synchronization with a driving frequency of 180 Hz.

FIG. 5 illustrates a method of displaying a moving picture in which data as shown in FIG. 2 is moved in an A direction in a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 5, in the liquid crystal display according to the exemplary embodiment of the present invention, the red, green, and blue light sources are sequentially turned on to sequentially display red, green, and blue data within one frame period in order to display a white image. . In FIG. 5, red data is displayed in the first subframe period, green data is displayed in the second subframe period, and blue data is displayed in the third subframe period. Green data, which is the second subframe data of the nth frame, and blue data, which is the third subframe data, are divided between red data, which is the first subframe data of the nth frame, and red data, which is the first subframe data of the n + 1th frame. It will be located at 1/3 of and 2/3 respectively. Due to the data displayed, the blur region does not appear on the actual perceptual image of the liquid crystal display according to the exemplary embodiment of the present invention, unlike the perceptual image of the conventional liquid crystal display shown in FIG. 2.

The liquid crystal display according to the exemplary embodiment of the present invention may be applied to both a sequential driving type liquid crystal display device in addition to the field sequential liquid crystal display device.

FIG. 6 is a diagram illustrating another example of the data modulator 2 shown in FIG. 3.

Referring to FIG. 6, the data modulator 2 includes first to third frame memories 24, 26, 28, and arithmetic unit 30.

The first frame memory 24 stores n data of the nth frame and supplies the data to the operation unit 30, and the second frame memory 26 supplies data of the n + 1th frame (n + 1 data). The third frame memory 28 stores the n + 2 th data (n + 2 data) and supplies the same to the arithmetic unit 30. That is, the first to third frame memories 24, 26, and 28 read input data at three times the speed, store each subframe data, and supply the subframe data in order to the operation unit. As a result, the operation unit 30 may calculate the data corresponding to each subframe period and immediately supply the data to the timing controller 4. The function of the calculator 30 is the same as that of the data modulator 2 shown in FIG.

As described above, in the liquid crystal display according to the exemplary embodiment of the present invention, the motion blur phenomenon may be minimized by differently specifying the position of the subframe data in every subframe in the sequential driving method.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1 is a view showing driving of a conventional field sequential liquid crystal display device;

FIG. 2 is a diagram illustrating an image displayed in FIG. 1. FIG.

3 illustrates a liquid crystal display according to an exemplary embodiment of the present invention.

4 is a diagram illustrating a data modulator of FIG. 3.

5 is a view illustrating driving of a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 6 is a diagram illustrating another example of the data modulator shown in FIG. 3. FIG.

<Brief description of symbols for the main parts of the drawings>

2: data modulation section 4: timing controller

6 data driver 8 gate driver

10 liquid crystal display panel 12 backlight

14, 16, 20, 22, 24, 26, 28: frame memory

18, 30: calculation unit

Claims (3)

A liquid crystal display device driven by dividing one frame period into k (integer of 2 or more) subframe periods, A liquid crystal display panel on which an image is displayed; A data driver supplying a data voltage to the liquid crystal display panel; A gate driver supplying scan pulses to the liquid crystal display panel; Modulates the input data, divides the interval k between the first subframe data position of the nth frame data and the first subframe data position of the n + 1th frame data, and specifies the position of each subframe data of the nth frame An output data modulator; And Converts the driving frequency of the input data by k times, synchronizes with the converted driving frequency, and specifies the driving timing of the subframe data of the n-th frame data positioned in the data modulator, wherein the data driver and the gate driver And a timing controller for controlling the control. The method of claim 1, The data modulator, A first frame memory for storing and outputting the n-th frame data; A second frame memory for storing and outputting the n + 1 th frame data; Comparing the first subframe data position of the nth frame data supplied from the first frame memory with the first subframe data position of the n + 1th frame data supplied from the second frame memory, wherein the nth Divide the interval between the first subframe data position of the frame data and the first subframe data position of the n + 1th frame data by k, and determine the second to kth subframe data positions of the nth frame data by An arithmetic unit for designating and outputting each of 1 / k to (k-1) / k points from the first subframe data position of the second frame data; And And k-1 third frame memories respectively storing second to k th subframe data of the nth frame data supplied from the computing unit and supplying the second to kth subframe data to the timing controller, And the first frame memory supplies the first subframe data of the nth frame data to the timing controller. The method of claim 1, The data modulator, A first frame memory for storing and outputting the n-th frame data; A second frame memory for storing and outputting the n + 1 th frame data; a third frame memory for storing and outputting n + 2th frame data; And Comparing the first subframe data position of the nth frame data supplied from the first frame memory with the first subframe data position of the n + 1th frame data supplied from the second frame memory, wherein the nth Divide the interval between the first subframe data position of the frame data and the first subframe data position of the n + 1th frame data by k, and determine the second to kth subframe data positions of the nth frame data by Designate 1 / k to (k-1) / k points from the first subframe data position of the second frame data, respectively, and supply the same to the timing controller, and supply the n + 1th frame data supplied from the second frame memory. A first subframe data position and the n + 2 th frame data supplied from the third frame memory Compares the first subframe data position of the data, k equally divides an interval between the first subframe data position of the n + 1 th frame data and the first subframe data position of the n + 2 th frame data, and The timing is determined by designating the second to k th subframe data positions of the n + 1 th frame data as 1 / k to (k-1) / k points from the first subframe data position of the n + 1 th frame data, respectively. And a computing unit for supplying the controller.

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