KR100853773B1 - Driving Method of Liquid Crystal Panel - Google Patents

Abstract

The present invention relates to a method of driving a liquid crystal panel which can improve screen quality by minimizing current consumption and stripes.

In a method of driving a liquid crystal panel according to an exemplary embodiment of the present invention, a plurality of unit pixels are formed in a region defined by a plurality of gate lines and a plurality of data lines crossing the plurality of gate lines, and a scan voltage applied to each of the plurality of gate lines. A method of driving a liquid crystal panel in which a switching element is controlled to direct a positive or negative data voltage to each of the plurality of unit pixels, the method comprising: an n-th gate line and a plurality of unit pixels; When the data voltages having different polarities are applied to a plurality of adjacent unit pixels defined by the first data line and the n + 1 th gate line crossing the second data line and the second data line crossing the first data line and the n + 1 th gate line, The n + 1 th gay such that a scan voltage is applied to overlap some period of turning on the switching element connected to the n th gate line When a scan voltage is applied to a line and a scan voltage is applied to the n-th gate line, a scan voltage is applied to the n-th gate line to the first unit pixel and the n + 1-th gate line to induce a data voltage. The scan voltage may be applied to the n + 1 th gate line to minimize the potential difference between the second unit pixels induced by the data voltage.

Description

Liquid crystal panel driving method {METHOD FOR OPERATING LIQUID CRYSTAL PANEL}

1A and 1B are explanatory diagrams of data voltage polarity of a conventional one dot inversion driving method.

2 is an explanatory diagram of data voltage polarity of a conventional two-dot inversion driving method.

3 is a driving waveform diagram of FIG. 2;

4 is a block diagram of a liquid crystal display device according to an exemplary embodiment of the present invention.

5 is a driving waveform diagram of a liquid crystal panel according to an exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

20: liquid crystal panel 25: unit pixels

30: data line 32: data driver

40: gate line 42: gate driver

80: drive system 81: system interface unit

82: timing controller 83: power unit

85: gamma power supply 87: DC / DC converter

The present invention relates to a method of driving a liquid crystal panel, and more particularly, to a method of driving a liquid crystal panel capable of improving screen quality and reducing current consumption.

As the information society develops, the demand for display devices is increasing in various forms, and in recent years, the LCD (Lipuid Crystal Display Device), PDP (Plasma Display Panel), ELD (Electro Luminescent Display), and VFD (Vacuum Fluorescent) Various flat panel display devices have been studied, and some of them are already used as display devices in various devices.

Among them, liquid crystal displays are most commonly used as a replacement for cathode ray tubes for mobile image display devices because of their excellent image quality, light weight, thinness, and low power consumption. In addition to the use of a variety of TV monitors have been developed.

An LCD (hereinafter, referred to as a liquid crystal display) is composed of two substrates coupled to face each other and a liquid crystal material injected between the two substrates to generate a phase transition according to a change in temperature or a change in concentration.

The liquid crystal is a material having an intermediate property between a liquid and a solid having a liquidity and a long range order of the solid. That is, it means that the solid crystal melts and becomes an intermediate state, not a solid crystal or a liquid, before it becomes a liquid. When the light is irradiated or an electric field or a magnetic field is added, it exhibits birefringence peculiar to optical anisotropic crystals, and within a certain temperature range. Both properties of liquid and crystal are shown.

Such a liquid crystal display device is composed of a liquid crystal panel which transmits white light in a form in which a liquid crystal layer is interposed between a TFT substrate and a color filter substrate facing the same, and a driving unit for driving the liquid crystal panel.

Here, the TFT substrate constituting the liquid crystal panel has a plurality of gate lines arranged in one direction at a predetermined interval and a plurality of data lines arranged at regular intervals in a direction perpendicular to the gate lines. And a plurality of thin film transistors and pixel electrodes respectively formed in a matrix pixel region defined by the gate line and the data line, and a black for blocking light of portions except the pixel region is formed on the color filter substrate. A black matrix layer, a color filter layer, a common electrode, and the like are formed.

In the liquid crystal display, when a signal is applied to one gate line, a data signal is applied to a pixel corresponding to the line to drive the liquid crystal panel.

However, the liquid crystal injected between the TFT substrate and the color filter substrate causes deterioration of characteristics when the DC voltage is applied for a long time, so that the polarity of the applied voltage is periodically changed to prevent the liquid crystal. This is called a polarity inversion driving method.

Such polarity inversion driving methods include frame inversion, line inversion, and dot inversion driving methods.

The frame inversion method is a method of applying the polarity of the data voltage applied to the liquid crystal with respect to the common electrode voltage in the unit of frame. That is, if a positive polarity data voltage is applied to an even frame, a negative polarity data voltage is applied to an odd frame. However, such a frame inversion driving method has the advantage of low current consumption during switching, but is sensitive to flicker caused by the asymmetry of transmittance of the positive and negative polarity, and crosstalk due to inter-data interference ( It is very vulnerable to crosstalk.

In addition, the line inversion driving method is a polarity inversion driving method generally used for low resolution (VGA, SVGA), and is a method of applying a data voltage so that the polarity of the pixel is changed in units of horizontal lines. That is, if the polarity is inverted at each gate line, if a positive polarity is applied to the odd line and a negative data voltage is applied to the even line, a negative voltage is applied to the odd line in the next frame. -) Data voltage of polarity is applied and data voltage of positive polarity is applied to even-numbered lines. Such a line inversion driving method has a disadvantage in that when the liquid crystal panel is enlarged, image distortion is deteriorated due to signal distortion and crosstalk in adjacent pixel electrodes due to an increase in resistance and capacitance.

Meanwhile, the dot inversion driving method is a polarity inversion driving method that realizes the best image quality at present, and is applied to high resolutions (XGA, SXGA, UXGA), and controls the polarity of data voltages between adjacent pixels in opposite directions in all directions. This is how to apply. That is, by inverting the polarities differently at the periodic intervals of the pixel electrodes, the flicker and the afterimage are easier to be suppressed than the frame inversion and line inversion driving methods.

This conventional dot inversion driving method will be described below with reference to the accompanying drawings.

FIG. 1A is an explanatory diagram of data voltage polarity of a first frame for explaining a one dot inversion driving method of a conventional liquid crystal display, and FIG. 1B is data of a second frame for explaining a one dot inversion driving method of a conventional liquid crystal display. Explanatory diagram of voltage polarity.

As described above, in a liquid crystal display device in which a plurality of gate lines G1 -Gn and a plurality of data lines S1 -Sn are arranged in a direction perpendicular to each other to form pixel regions in a matrix form, in all directions of up, down, left and right. The data voltage is applied such that polarities of the data voltages between adjacent pixels are reversed. In the next frame, the polarity of each pixel area is opposite to that of the previous frame.

That is, in the first frame, when driving the odd gate line, the odd-numbered data lines S1, S3, S5, ... are applied with a positive polarity data voltage and the even-numbered data lines S2, S4, S6. (...) is applied with a data voltage of negative polarity. When the even-numbered gate line is driven, the odd-numbered data lines S1, S3, S5, ... are applied with a negative polarity data voltage and the even-numbered data lines S2, S4, S6, ... A positive polarity data voltage is applied.

In the second frame, the odd-numbered data lines S1, S3, S5, ... are applied with a negative polarity data voltage and the even-numbered data lines S2, S4, S6 during driving of the odd-numbered gate lines. The data voltage of positive polarity is applied to (..). When driving the even-numbered gate line, odd-numbered data lines S1, S3, S5, ... are applied with a positive polarity data voltage, and even-numbered data lines S2, S4, S6, ... A negative data voltage is applied.

However, when the liquid crystal display is driven in such a 1 dot inversion method, frequent switching operations increase power consumption and drive frequency, resulting in problems such as electromagnetic interference or noise.

In order to solve this problem, a two-dot inversion driving method has been developed. In this case, as shown in FIG. 2, the polarity of the data voltage is inverted by one pixel electrode in the row direction (the direction of the gate line), and the column direction is shown. In the direction of the data line, the polarity of the data voltage is inverted every two pixel electrodes, which has the advantage of reducing the power consumption and driving frequency than the one-dot inversion driving method.

The driving waveform diagram of the two-dot inversion driving method is briefly described as follows.

Referring to the unit pixel in the column direction, for example, as shown in Figure 3, when the scan voltage corresponding to each of the n, n + 1, n + 2nd gate line is sequentially applied, by the scan voltage The thin film transistor is controlled so that a data voltage corresponding to the line is applied to each unit pixel.

That is, when a thin film transistor is turned on because a scanning voltage of one horizontal cycle time (1H) is applied to the nth gate line, a corresponding positive data voltage is applied to a unit pixel, and the n + 1th gate is applied. When the scan voltage is applied to the line, the positive data voltage as described above is applied.

On the other hand, when the scanning voltage is applied to the n + 2th gate line for one horizontal period time (1H) and the thin film transistor is turned on, the negative data voltage is applied to the unit pixel by the two dot inversion driving method. .

At this time, when the data voltage applied to the unit pixel is changed from the positive polarity to the negative polarity or the negative polarity to the positive polarity, the unit is due to the large potential difference A between the unit pixels. A data coupling phenomenon in which the data voltage leaks to the pixel electrode of the pixel occurs.

In other words, a luminance difference between lines due to data coupling occurs at a portion where the polarity of the data voltage is reversed by giving two pixel electrodes in the column direction. This causes a problem that streaks along the gate line are generated in the part where the polarity is reversed, and the color to be displayed is discolored, thereby degrading the image quality.

Accordingly, an object of the present invention is to provide a method of driving a liquid crystal panel that can improve screen quality by minimizing current consumption and streaking.

In the method of driving the liquid crystal panel according to the exemplary embodiment of the present invention, a plurality of unit pixels are formed in an area defined by a plurality of gate lines and a plurality of data lines crossing the plurality of gate lines, and each of the plurality of gate lines A method of driving a liquid crystal panel in which a switching element is controlled by a scan voltage applied to the organic light emitting diode to induce a positive or negative polarity data voltage to each of the plurality of unit pixels. When applying data voltages having different polarities to a plurality of adjacent unit pixels defined by the n-th gate line, the first data line crossing the n-th gate line, and the n + 1-th gate line and the second data line crossing the n-th gate line, During a period during which a scan voltage is applied to an n-th gate line to turn on a switching device connected to the n-th gate line When the scan voltage is applied to the n + 1 th gate line, and when the scan voltage is applied to the n th gate line, a scan voltage is applied to the n th gate line to induce a data voltage and n The scan voltage is applied to the +1 th gate line to apply a scan voltage to the n + 1 th gate line to minimize the potential difference between the second unit pixels induced by the data voltage.

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

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

As shown in the drawing, the liquid crystal display device displays red (hereinafter, R), green (hereinafter, G), and blue (hereinafter, B) signals, which are display image signals input from the driving system 80, that is, a PC or a notebook computer. A system interface unit (81) for transmitting to the timing controller (82) for receiving a video signal from the system interface unit (81) and generating various control signals and data so that the liquid crystal panel (20) can be stably driven; And a data driver 32 for converting data from the timing controller 82, that is, an image signal, into an analog signal and applying a voltage to each data line 30 formed in the vertical direction of the liquid crystal panel 20. A gate driver 42 for inputting a display control signal received from the controller 82 to apply a scan voltage to each gate line 40 formed in the left and right directions of the liquid crystal panel 20; A power supply 83 for receiving power from the power supply unit 80 and supplying power required for each unit; and a reference voltage for digital / analog conversion of the data driving unit 32 by receiving power supplied from the power unit 83; By using the gamma power supply unit 85, and the voltage Vin from the power unit 83 generates various voltages used in the liquid crystal module, for example, V _CC , V _DD , V _GH , V _GL voltages. It comprises a DC / DC converter 87.

Here, the liquid crystal panel 20 includes a first substrate and a second substrate on which the liquid crystal layer is interposed. The first substrate includes a plurality of data lines 30 spaced apart at regular intervals in a vertical direction, and a plurality of gate lines 40 intersecting with the data lines 30 in a left and right direction are formed to form a plurality of matrix-like structures. The unit pixels 25 are defined. Thin film transistors (not shown) for switching data, that is, an image signal, are formed at a portion where the gate line 40 and the data line 30 cross each other, and each unit pixel 25 is formed in each of the unit pixels 25. Pixel electrodes receiving data signals are formed by the thin film transistor.

Although not shown in the drawing, the second substrate which is bonded to the first substrate to form the liquid crystal panel 20 forms a black matrix layer that serves as light blocking, and implements three primary colors of R, G, and B. The color filter layer, the ITO film | membrane for a common electrode, etc. are formed. Here, one color may be realized by a combination of three pixel units including three pixel electrodes and color filter layers R, G, and B corresponding thereto.

Meanwhile, the data driver 32 generates a liquid crystal driving voltage by performing digital / analog conversion on the reference voltage output from the gamma power supply 85 based on the signals of R, G, and B, and generates the liquid crystal driving voltage. A voltage is applied to the data line 30 of the liquid crystal panel 20 every scanning. The gamma power supply unit 85 generates the reference voltage for generating the liquid crystal driving voltage by dividing the positive polarity into the positive polarity and the negative polarity. The positive polarity refers to an upper voltage based on a common voltage, and the negative polarity refers to a lower voltage based on a common voltage.

Looking at the driving method of the liquid crystal display device having such a configuration as follows.

As shown in FIG. 5, scan voltages corresponding to the n, n + 1, and n + 2th gate lines are sequentially applied, and the thin film transistor is controlled by the scan voltages so that the data voltage corresponding to the line is changed. Is applied to each unit pixel. In this case, the scan voltage is sequentially applied to each gate line for two horizontal periods 2H. Specifically, the scan voltage is applied to the n-th gate line for 2 horizontal periods (2H) to turn on the switching element connected to the n-th gate line, and the scan voltage is applied to the n-th gate line at the n + 1th gate line. After the 1 horizontal period 1H is applied, the scan voltage is supplied for 2 horizontal periods 2H so as to overlap with the other 1 horizontal period 1H to turn on the connected switching elements. Here, after the scanning voltage of one horizontal period (1H) is applied to the n-th gate line, the n + 1-th gate line to turn on the switching element connected to the n + 1-th gate line, for example, A scan voltage of 50% or less of the scan voltage may be applied to the n + 1 th gate line.

In other words, when a scan voltage of 2 horizontal periods 2H is applied to each gate line, 50% of false data is precharged in one horizontal period of 2 horizontal periods 2H to the nth gate line. (Precharging), a scan voltage of 100% is applied in the remaining one horizontal period. At this time, the scan voltage of 50% is simultaneously precharged to the n + 1 th gate line, which can reduce the potential difference A due to the precharging effect between adjacent unit pixels that are changed to different polarities. It is possible to reduce the horizontal fringes due to data coupling, which is presented as a problem when driving the liquid crystal panel by the conventional two dot inversion driving method. When the scan voltage is applied to the n-th gate line, the potential difference A minimizes the potential difference A by maximizing the precharging effect by adjusting the voltage amount of the scan voltage applied to the n + 1-th gate line. Although it is possible that much current is consumed, it is preferable to apply a scan voltage of 50%.

In addition, the potential difference between unit pixels may be minimized even between frames in which the unit pixels change to different polarities, and the liquid crystal panel may be driven by minimizing current consumption by precharging.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

The driving method of the liquid crystal panel of the present invention has the following effects.

First, the potential difference A may be reduced due to the precharging effect between adjacent unit pixels having different polarities, thereby reducing lateral fringes due to data coupling.

Second, the potential difference between unit pixels may be minimized even between frames in which unit pixels change to different polarities, and the liquid crystal panel may be driven by minimizing current consumption by precharging.

Claims (3)

A plurality of unit pixels are formed in an area defined by a plurality of gate lines and a plurality of data lines crossing the plurality of gate lines, and the switching element is controlled by a scanning voltage applied to each of the plurality of gate lines, so that the positive polarity or In the driving method of the liquid crystal panel in which a negative data voltage is induced in each of the plurality of unit pixels, Data voltages having different polarities in a plurality of adjacent unit pixels defined by an n-th gate line, a first data line crossing the n-th gate line, and an n + 1-th gate line and a second data line crossing the plurality of unit pixels. When authorizing, A scan voltage is applied to the n-th gate line to apply a scan voltage to the n + 1 th gate line so as to overlap a part of a period of turning on the switching element connected to the n-th gate line, When the scan voltage is applied to the n-th gate line, a scan voltage is applied to the n-th gate line to induce a data voltage, and a scan voltage is applied to the n + 1-th gate line so that a data voltage is applied. And applying a scanning voltage to the n + 1 th gate line to minimize the potential difference between the second unit pixels. The method of claim 1, And the scan voltage is sequentially applied to each of the plurality of gate lines for two horizontal periods. The method of claim 2, When the scanning voltage of the two horizontal periods is applied to each of the plurality of gate lines, 50% of the scanning voltage is applied during one horizontal period of the two horizontal periods, and 100% of the scanning voltage is applied during the remaining one horizontal period. A method of driving a liquid crystal panel, characterized in that.

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