KR100206563B1 - Driving method of thin-film transistor liquid crystal display device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of driving a thin film transistor liquid crystal display device, the method comprising: a gate driving means for driving a scan line of a liquid crystal panel, a source driving means for driving a signal line of a liquid crystal panel, a gate driving means and a source driving by receiving an image signal and a control signal An active matrix thin film transistor liquid crystal display comprising drive control means for processing the timing of the means, comprising: a first field in which one frame drives only odd scan lines to form a screen and a second field in which only even scan lines are driven to form a screen The interlaced scanning is performed so that the interlaced scanning is doubled by one horizontal scanning time to sufficiently increase the charging time, thereby improving the deterioration of the charging characteristics generated in the large-resolution, high-resolution active matrix thin film transistor liquid crystal display. RGB for each By performing the pixel inversion driving which can independently adjust the inversion signal of one gradation voltage, it compensates for the screen flicker characteristic which may be caused by this interlaced scan, and prevents image quality deterioration.

Description

Driving Method of Thin Film Transistor Liquid Crystal Display

FIG. 1 is a block diagram of a conventional active matrix thin film transistor liquid crystal display, (a) is a single bank method, (b) is a diagram showing a dual bank method,

2 is a pixel equivalent circuit diagram of a liquid crystal panel of a conventional active matrix thin film transistor liquid crystal display device,

3 is a view showing a display method of a liquid crystal panel of a conventional active matrix thin film transistor liquid crystal display device, (a) is a view showing a display method of the first field, (b) is a view showing a display method of the second field. ego,

4 is a voltage waveform diagram applied to a panel of a conventional active matrix thin film transistor liquid crystal display device,

5 is a voltage waveform diagram applied to a panel of a conventional large liquid crystal display device.

6 is a view showing a screen display method in a thin film transistor liquid crystal display device according to a first embodiment of the present invention,

7 is a voltage waveform diagram applied to a panel of the thin film transistor liquid crystal display according to the first embodiment of the present invention.

8 is a diagram illustrating a screen display method in a single bank thin film transistor liquid crystal display device according to a second embodiment of the present invention.

9 is a voltage waveform diagram applied to R, G, and B in the single bank thin film transistor liquid crystal display according to the second embodiment of the present invention.

FIG. 10 is a diagram illustrating a screen display method of a single bank thin film transistor liquid crystal display device according to a third exemplary embodiment of the present invention.

FIG. 11 is a voltage waveform diagram applied to R, G, and B in the single bank thin film transistor liquid crystal display according to the third embodiment of the present invention.

FIG. 12 is a diagram illustrating a screen display method of a dual bank type thin film transistor liquid crystal display according to a fourth exemplary embodiment of the present invention.

FIG. 13 is a voltage waveform diagram applied to upper and lower R, G and B in the dual bank type thin film transistor liquid crystal display according to the fourth exemplary embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1 liquid crystal panel 3, 9 gate driver

5, 11, 13: source drive unit 7, 15: drive control unit

17: signal line 19: scanning line

Cstg: Holding Capacity Clc: Liquid Crystal Capacity

Vp: pixel voltage Vcom: common voltage

TFT: thin film transistor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, an active matrix thin film transistor (TFT) that doubles one horizontal scanning time through interlaced scanning to sufficiently lengthen a charging time. A driving method of a liquid crystal display device.

Hereinafter, a driving method of a conventional active matrix thin film transistor liquid crystal display device will be described with reference to the accompanying drawings.

1A and 1B are block diagrams of a general active matrix thin film transistor liquid crystal display, (a) is a single bank method, and (b) is a block diagram showing a dual bank method.

As shown in FIG. 1A, a basic structure of a general single bank type active matrix thin film transistor liquid crystal display device includes a gate driver 3 driving a scan line of a liquid crystal panel 1 and a signal line of a liquid crystal panel 1. And a driving controller 7 which receives a source driver 5, an image signal, and a control signal to process timings of the gate driver 3 and the source driver 5.

In addition, as shown in FIG. 1B, the basic structure of a general dual bank type active matrix thin film transistor liquid crystal display device includes both the gate driver 9 and the liquid crystal panel 1 which drive the scanning line of the liquid crystal panel 1. And a driving control unit 15 for processing the timings of the gate driving unit 9 and the source driving units 11 and 13 by receiving an input of an image signal and a control signal.

Here, the pixel equivalent circuit of the liquid crystal panel 1 is shown in FIG.

In FIG. 2, Vd is a video signal applied to the signal line 17, Gn is a selection pulse applied to the scan line 19, and Vp represents a pixel voltage.

In FIGS. 1 and 2, the driving controllers 7 and 15 receive an image signal and a control signal and apply a video signal to the corresponding signal line 17 through the source driving units 5, 11 and 13, and the gate driving unit ( A selection pulse is applied to the scan line 19 to turn on the thin film transistor TFT through 3 and 9. In this manner, the video signal voltage applied through the signal line 17 is charged in the liquid crystal capacitor Clc and the sustain capacitor Cstg while the thin film transistor TFT is turned on.

When the thin film transistor TFT is turned off by the selection pulse applied to the scan line 19, the voltage charged in the liquid crystal capacitor Clc and the holding capacitor Cstg is applied to the thin film transistor TFT for the next video signal application voltage. It remains until it is turned on.

As described above, the thin film transistor TFT repeatedly transmits the corresponding video signal voltage to the liquid crystal capacitor Clc and the holding capacitor Cstg, and the liquid crystal is driven by the voltage so that an image appears on the liquid crystal panel 1. do.

3 is a view showing a display method of a liquid crystal panel 1 of a general active matrix thin film transistor liquid crystal display device, in which (a) shows a display method for the first field, and (b) shows a display method for the second field. Drawing.

Here, + shown in FIG. 3A indicates that the polarity is relatively relative to the common voltage, and − shown in FIG. 3B indicates that the polarity is negative.

A positive video signal is applied to the liquid crystal panel 1 by the source drivers 5, 11, and 13, and the thin film transistor ON voltage is applied by the gate drivers 3 and 9 to the first scan line shown in FIG. 3A. If not, the screen is displayed on the first scanning line. Next, a new video signal is applied to the liquid crystal panel 1, and when the thin film transistor on voltage is applied to the second scan line, a screen is displayed on the second scan line.

In this way, when the screen is displayed on the nth scan line, the screen display of the first field is ended and the screen as shown in FIG. 3a is finally displayed.

Similarly, when a negative video signal is applied to the liquid crystal panel and the screen of the second field is displayed, the screen as shown in FIG.

Here, the first field and the second field are combined to form one frame, and one frame displays one screen. However, you can actually display one screen with one field.

As such, in the related art, each scan line is sequentially driven one by one in order to form a screen, and the waveform of the applied voltage is shown in FIG. 4.

As shown in FIG. 4, the Gn selection pulse is applied to the scan line 19 to turn on the thin film transistor TFT. At this time, the Vd voltage applied to the signal line 17 is applied to the holding capacitor Cstg and the liquid crystal capacitor Clc. Is charged). This charging voltage is the pixel voltage Vp, which falls slightly when the Gn pulse goes down.

Here, the time that the thin film transistor (TFT) is turned on by the Gn selection pulse is one horizontal scanning time, and one field corresponds to about 16.7 msec (60 Hz), so one frame corresponds to about 33.3 msec (30 Hz). do.

In the conventional thin film transistor liquid crystal display device, a low voltage driving IC (integrated circuit) having low power consumption and relatively easy manufacturing is used, and this thin film transistor liquid crystal display device is mainly applied to a notebook computer or the like. In addition, since the size of the liquid crystal display device of 12.X or less predominantly, low-voltage line inversion driving method with low power consumption was generally adopted.

However, thin-film transistor liquid crystal display devices are gradually enlarged to 20 or more, and high resolution such as extended graphics array (XGA) and engineering work station (EWS) at resolutions of video graphics array (VGA) and super video graphics array (SVGA). As the product having the need increases, the wiring resistance increases, and the capacitance component also increases. Due to this increase in resistance and capacitance components, the voltage charged to each pixel is not constant depending on the position of the panel of the thin film transistor liquid crystal display, resulting in a difference in charging voltage, which increases cross talk and increases the contrast ratio. It will have a bad effect on image quality such as reduction.

In addition, the on-signal delay of the thin film transistor liquid crystal display is increased to overlap the next on-signal. In this overlapping portion, the voltage charged to the pixel is momentarily discharged, and the sustain potential of the pixel is smaller than the voltage to be input. Likewise results in increased crosstalk and reduced contrast ratio.

Thus, the voltage waveform applied to the panel in the large liquid crystal display is shown in FIG.

As shown in FIG. 5, the pixel voltage charged in the liquid crystal capacitor Clc and the storage capacitor Cstg in the large liquid crystal display is Vp '.

In this case, Vp 'is smaller than Vp, which is a pixel voltage of a conventional small liquid crystal display device, which causes a deterioration in image quality. In order to solve this problem, the conventional liquid crystal display device is driven such that the overlapping time is reduced when the thin film transistor on signal is turned off.

Therefore, when the thin film transistor liquid crystal display is driven using this method, the actual thin film transistor on time is shorter than one horizontal scan time. In particular, the larger the high-resolution thin-film transistor liquid crystal display device, the smaller it becomes, which causes the pixel voltage charging problem. Also, in order to obtain sufficient pixel voltage, the size of the thin film transistor, that is, the width, must be increased to increase the amount of current, and the wiring resistance of the signal line is increased. In order to reduce the problem, there is a problem in that a material having a very good conductivity or a thick wiring is developed and applied.

Accordingly, an object of the present invention is to solve the above-described problems, and the charging characteristics generated in a large-resolution, high-resolution active matrix thin film transistor liquid crystal display device by doubling the horizontal scanning time by interlaced scanning to sufficiently increase the charging time. This can be generated by this interlaced scan by improving the degradation and driving a pixel inversion that can independently adjust the inverted signal of the gradation voltage for each of the R (red) G (green) B (blue). The present invention provides a method of driving a thin film transistor liquid crystal display device capable of improving image quality by compensating flicker.

As a means for achieving the above object, the present invention provides a gate driving means for driving a scan line of a liquid crystal panel, a source driving means for driving a signal line of a liquid crystal panel, an image signal and a control signal, An active matrix thin film transistor liquid crystal display including drive control means for processing timing, comprising: a frame comprising a first field for driving only odd scan lines to form a screen and a second field for driving only even scan lines to form a screen A method of driving a thin film transistor liquid crystal display device characterized in that the interlaced scanning is performed.

Here, one horizontal scanning time by interlaced scanning corresponds to one frame, and one frame is longer than one horizontal scanning time by sequential scanning because it consists of a first field of odd scan line driving and a second field of even scan line driving. Thus, the pixel voltage is sufficiently charged.

In addition, since the liquid crystal drive signal inversion period of one pixel displayed by interlaced scanning is twice as long as in sequential scanning, there is a possibility that screen flickering characteristics are worse than the screen displayed by sequential scanning.

This screen flickering characteristic is caused by unbalance of white when the video signal voltage applied to the liquid crystal panel is positive and negative, so that the inversion period and phase for each of R, G, and B can be arbitrarily adjusted. By implementing various pixel inversion driving combinations, white imbalance with neighboring pixels can be compensated for.

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

6 is a diagram illustrating a screen display method in the thin film transistor liquid crystal display according to the first embodiment of the present invention.

As shown in FIG. 6, only one odd scan line is driven in the first field and only even scan lines are driven in the second field, so that one frame in which the first field and the second field are combined is one screen. Here, a waveform relating to the voltage applied to the liquid crystal panel for displaying the screen shown in FIG. 6 is shown in FIG.

As shown in FIG. 7, the problem that the pixel voltage is not sufficiently charged during sequential scanning can be solved because the time for turning on the thin film transistor due to interlaced scanning is twice as long as sequential scanning. have.

Since the screen displayed by interlaced scanning is displayed by one frame driving, there is a possibility that the screen flicker characteristic is worse than the screen displayed by progressive scanning.

FIG. 8 is a diagram illustrating a screen display method of a single bank thin film transistor liquid crystal display device according to a second exemplary embodiment of the present invention, and FIG. 9 is a voltage waveform diagram applied to R G B in the liquid crystal display device.

As shown in FIG. 8 and FIG. 9, the first field and the second field are formed by the liquid crystal voltage inversion period control signal of each of R G B, and as a result, one frame is formed to display one screen.

One frame formed here compensates for the white imbalance because it is implemented by pixel inversion driving, thereby improving the screen flicker characteristic.

FIG. 10 is a diagram illustrating a screen display method of a single bank thin film transistor liquid crystal display device according to a third exemplary embodiment of the present invention, and FIG. 11 is a voltage waveform diagram applied to R, G, and B in the liquid crystal display device. to be.

As shown in FIGS. 10 and 11, the first and second fields are formed by the liquid crystal voltage inversion period control signals of R, G, and B, respectively, and as a result, one frame is formed to form one screen. Is displayed.

One frame formed here compensates for the white imbalance because it is implemented by pixel inversion driving, thereby improving the screen flicker characteristic.

FIG. 12 is a diagram illustrating a screen display method of a dual bank type thin film transistor liquid crystal display according to a fourth exemplary embodiment of the present invention, and FIG. 13 is applied to upper and lower R, G, and B in the liquid crystal display. Voltage waveform diagram.

As shown in FIGS. 12 and 13, the first field and the second field are formed by the liquid crystal voltage inversion period control signals of up R, G, B and down R, G, and B, respectively. As a result, one frame is formed and one screen is displayed.

One frame formed here compensates for the white imbalance because it is implemented by pixel inversion driving, thereby improving the screen flicker characteristic.

As described above, in the embodiment of the present invention, the charge time is sufficiently increased by doubling one horizontal scanning time through interlaced scanning to improve the deterioration of the charging characteristics generated in the large-resolution, high-resolution active matrix thin film transistor liquid crystal display device, and A pixel inversion driving device capable of independently adjusting the inversion signal of the gradation voltage for each of R, G, and B is used to compensate for the screen flicker characteristic that may be caused by the interlaced scan, thereby preventing the deterioration of image quality. A driving method can be provided.

Claims (5)

An active matrix including gate driving means for driving a scan line of a liquid crystal panel, source driving means for driving a signal line of a liquid crystal panel, and driving control means for receiving an image signal and a control signal and processing timing of the gate driving means and the source driving means. In a thin film transistor liquid crystal display device, one frame is interlaced so as to include a first field for driving only odd scan lines to form a screen and a second field for driving only even scan lines to form a screen, and the drive control means is horizontal Outputs a first gate drive signal synchronized with the odd-numbered clock of the synchronization signal and a second gate drive signal synchronized with the even-numbered clock, and the source driving means outputs a positive gray level voltage signal to the R signal line in the first field; Is applied to the G signal line, and a negative gray voltage signal is applied to the G signal line. By applying a positive gray voltage signal, applying a negative gray voltage signal to the R signal line in the second field, applying a positive gray voltage signal to the G signal line, and applying a negative gray voltage signal to the B signal line, And performing pixel inversion driving during one plane by turning the pixel gray voltage applied to the first and second fields into an inverted state. The method of claim 1, wherein the source driving means applies a positive gray voltage signal to the R signal line in the first field, applies a positive gray voltage signal to the G signal line, and applies a negative gray voltage signal to the B signal line. And applying a negative gray voltage signal to the R signal line in the second field, applying a negative gray voltage signal to the G signal line, and applying a positive gray voltage signal to the B signal line. Method of driving the display device. 2. The method of claim 1, wherein the source driving means is located on both the upper side and the lower side of the liquid crystal panel to drive different signal lines of the liquid crystal panel. The method of claim 3, The source driving means located on the upper side adjusts the period and phase of the gray level inversion signal applied to each of the upper R, G, and B signal lines, and the source driving means located on the lower side, A method of driving a thin film transistor liquid crystal display device, characterized in that the period and phase of a gray level inversion signal applied to each of the lower R, G, and B signal lines are adjusted. The method of claim 4, wherein The source driving means located on the upper side applies the positive gray voltage signal to the upper R signal line in the first field, applies the positive gray voltage signal to the upper G signal line, and applies the positive gray voltage signal to the upper B signal line. In the second field, the negative gray voltage signal is applied to the upper R signal line, the negative gray voltage signal is applied to the upper G signal line, and the negative gray voltage signal is applied to the upper B signal line. The source driving means positioned in the first field applies the negative gray voltage signal to the lower R signal line in the first field, applies the negative gray voltage signal to the lower G signal line, and applies the negative gray voltage signal to the lower B signal line. In the second field, a positive gray voltage signal is applied to the lower R signal line, and a positive gray voltage signal is applied to the lower G signal line. Method of driving a thin film transistor liquid crystal display device, characterized in that for applying a positive gradation voltage signal on the line.