KR100559225B1 - Method for driving dot inversion of lcd - Google Patents

Abstract

The present invention relates to a dot inversion driving method of a liquid crystal display device in which a resolution is increased by using a one line gate pulse when the polarity of the previous frame is the same and a dual line gate pulse when the polarity is different. Invert the pixel polarity each time to form a full screen 1 frame, and the next frame shifts the polarity of the current frame up one line and inverts again, using the one-line gate pulse when the polarity is the same as the previous frame. Use dual line gate pulses for polarities other than.

Description

Dot inversion driving method of liquid crystal display {METHOD FOR DRIVING DOT INVERSION OF LCD}

1 is a driving block diagram of a general large screen TFT LCD.

2 is a block diagram showing pixel polarity during shift 2 dot inversion driving

FIG. 3 is a diagram illustrating a gate selection outline of Frame # 2 of FIG. 3.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to driving a liquid crystal display, and in particular, when the polarity of the previous frame is the same, one dot gate pulse is used, and in another case, the dual line gate pulse is used to increase the resolution. An inversion driving method.

As TFT LCDs become larger in size and higher in resolution, the filling rate and flicker of panels become a big problem.

This is because the time to charge one gate is significantly reduced as the number of gate lines to be charged for a certain frame time increases.

This causes serious problems for the flicker as the panel size increases and the overall uniformity drops.

Flicker is a kind of screen shaking, which causes the screen to shake in the eyes of the user due to the optical asymmetry caused by the distortion of the input data voltage.

In order to be able to see a shake-free screen in the liquid crystal display, at least 60 scannings should be performed per second. In driving the liquid crystal display, an AC driving method in which the data voltage Vs is inverted for each frame based on the common voltage Vcom is used to prevent deterioration of the liquid crystal.

The difference between the data voltage Vs applied to the source of the thin film transistor and the pixel voltage Vp actually applied to the liquid crystal capacitor occurs by ΔV. This is called a kick-back voltage.

This kick-back voltage is caused by the parasitic capacitance Cgd existing between the gate and drain of the thin film transistor. The kick-back voltage causes the data voltage Vs to be distorted and thus transmittance of the liquid crystal. Changes result in flicker.

Hereinafter, a driving method of the liquid crystal display of the prior art will be described with reference to the accompanying drawings.

1 is a driving block diagram of a general large screen TFT LCD.

The driving block of the large screen TFT LCD includes a liquid crystal panel 1, a row driver 2 for applying a gate driving signal to the liquid crystal panel 1, and a column driver 3 for applying a data signal to the liquid crystal panel 1; ), A frame memory 4 for storing data input from an external system in units of frames, and a control signal (Vsync, Hsync) required for driving the liquid crystal panel 1 by the row driver 2 and the column driver 3. And a timing controller 5 for outputting a clock and the like (V, Vgl, Vcc, Vcom).

Here, the liquid crystal panel 1 defines a plurality of pixel regions by crossing a plurality of gate lines and data lines, and a data signal transmitted from the column driver 3 at an intersection portion of each of the gate lines and the data lines. A thin film transistor for switching is configured.

The thin film transistor includes a gate electrode formed on a glass substrate, a gate insulating film formed on the entire surface including the gate electrode, a semiconductor layer formed on the gate insulating film and used as a channel layer of the thin film transistor, and formed on the semiconductor layer. It consists of a source and a drain electrode.

Here, the liquid crystal capacitor having one side as the pixel electrode and the other side as the common electrode is connected to the drain electrode of the thin film transistor.

In the driving of the liquid crystal display device of the related art using such a driving block, in order to solve the charging rate and the flickering problem, the frame rate is added to increase the filling rate and several new driving methods are proposed to improve the flicker.

However, these improvement methods are accompanied by the addition of expensive and large-area parts to increase the product cost and place many restrictions on the circuit configuration.

Currently, when driving SXGA or UXGA using frame memory, several Mbytes of memory are required. Therefore, the internal memory cannot be used inside the controller.

The driving method of such a liquid crystal display of the prior art has the following problems.

In order to solve the charge rate and flicker problem, the frame rate is added to increase the charge rate and several new driving schemes are proposed to improve the flicker. However, since the memory cost is increased and the memory requires a large area and a lot of wiring, the circuit configuration is improved. Complicated.

The present invention is to solve the problem of the driving method of the prior art liquid crystal display device, and if the same polarity as the previous frame, one line gate pulse is used, otherwise the dual line gate pulse using a resolution SUMMARY OF THE INVENTION An object of the present invention is to provide a dot inversion driving method of a liquid crystal display device which can be increased.

In the dot inversion driving method of the liquid crystal display according to the present invention for achieving the above object, in the driving of the liquid crystal display device, the pixel polarity is inverted every two lines to configure one frame of the entire screen, and the next frame is the current frame. The polarity of is shifted one line upward and inverted again. One line gate pulse is used when the polarity is the same as the previous frame, and a dual line gate pulse is used when the polarity is different from the previous frame.

Hereinafter, the dot inversion driving method of the liquid crystal display according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a diagram illustrating a pixel polarity during shift 2 dot inversion driving, and FIG. 3 is a diagram illustrating a gate selection outline of Frame # 2 of FIG. 3.

The present invention solves the problem of charging a large screen, high resolution TFT LCD by doubling the charging time by using a shift 2 dot driving method instead of the driving method using a frame memory, and randomly polarizes the polarity voltage. It is intended to improve flicker characteristics by making it into one shape.

As shown in FIG. 2, the polarity in the first frame (frame # 1) is shifted upward to have the reversed polarity in the next frame.

When the pixel polarity is made in this way, a waveform similar to the gate selection shown in FIG. 3 is obtained.

Here, it can be seen that the charging time of the gate is doubled and the time corresponding to one line alternately appears. In the case of a line in which the charging time corresponds to one line, it can be seen that the previous frame has the same polarity.

In this case, the gate charging time is doubled than the actual line time in both cases. The preceding time is the precharge time and the remaining time is the time to charge the actual data.

In addition, the pixel polarity shown in FIG. 2 shows that the generation of flicker is significantly reduced in the skip 1 dot pattern, which often measures flicker.

Hereinafter, the pixel polarity implemented in the present invention will be described in more detail.

The pixel polarity is reversed every two lines to form one frame of the entire screen. The next frame is configured by shifting the polarity of the current frame upward by one line and inverting it again.

This can be seen in detail in FIG. 2 in which the pixel polarity is displayed for each frame. By configuring the pixel polarity as described above, gate selection waveforms can be obtained as shown in FIG. 3. The waveform shown in FIG. 3 shows the gate selection waveform when frame # 2.

Referring to the gate selection waveform shown in FIG. 3, the width ('H' level) of the waveform alternates between two line widths and one line width.

In these two cases of the gate selection waveform, the gate filling rate is doubled by the following principle.

In the driving method of the present invention, since the gate selection waveform having two line widths has the same pixel polarity, there is an effect of precharging the next line by the time corresponding to one line.

In addition, the gate selection waveform representing one line width has the same polarity as the same line in the previous frame.

This can be seen from the gate selection waveform of frame # 2 and the pixel polarity shown in FIG. As such, since the charging is performed with the same polarity in the previous frame, the same effect as precharging can be obtained.

In addition to doubling the gate charge time in this manner, as can be seen from the pixel polarity shown in FIG. 2, the pixel polarity exhibits extremely small flicker in the skip 1 dot pattern, which is a flicker check pattern.

Another problem is that the pixel clock is greatly increased, which can be halved if the entire screen is split in two using one or two line memory.

In this case, since the small memory is used, the line memory can be implemented using the internal memory of the controller, not the external memory.

Such a dot inversion driving method of the liquid crystal display of the present invention has the following effects.

By inverting the pixel polarity every two lines, one frame of the entire screen is formed, and the next frame is configured by shifting the polarity of the current frame one line upward and inverting again, thereby improving flicker characteristics without adding additional components.

This has the effect of providing a large area, high resolution liquid crystal display device.

Claims (3)

In driving the liquid crystal display device, Invert the pixel polarity every 2 lines to form a full screen 1 frame, and the next frame shifts the polarity of the current frame up 1 line and inverts again. A one-line gate pulse is used when the polarity is the same as the previous frame, and a dual line gate pulse is used when the polarity is different from the previous frame. The dot inversion driving of the liquid crystal display device according to claim 1, wherein the gate selection waveform having two line widths has the same pixel polarity and thus precharges the next line for a time corresponding to one line. Way. The dot inversion driving method of claim 1, wherein the gate selection waveform having one line width has the same polarity as the same line in a previous frame.

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