CN100414592C - Driving and data voltage signal adjusting method for active matrix type liquid crystal display - Google Patents

Abstract

A driving and data voltage signal adjusting method for an active matrix liquid crystal display. The liquid crystal display is provided with a pixel unit array, and each pixel unit comprises a pixel electrode, a corresponding common electrode and a liquid crystal layer positioned between the two electrodes. The method comprises the following steps. First, a data voltage signal is applied to the pixel electrode. The data voltage signal is an AC voltage signal V of a specific gray level (nth level). The first compensation voltage signal V' is applied to the pixel electrode while the alternating voltage signal is applied to compensate the potential shift of the data voltage signal due to the parasitic capacitance and the coupling capacitance of the pixel unit. And, a second compensation voltage signal vasy is applied to the pixel electrode while the ac voltage signal is applied to compensate for a potential shift due to asymmetry of the pixel electrode with the common electrode material or geometry.

Description

Driving and data voltage signal adjustment method of active matrix liquid crystal display

technical field

The invention relates to a driving method of a liquid crystal display, in particular to a driving method of an active matrix liquid crystal display and a data voltage signal adjustment method.

Background technique

With the rapid progress of thin film transistor manufacturing technology, liquid crystal displays are widely used in personal digital assistants (PDAs), notebook computers, digital cameras, camcorders, Various electronic products such as mobile phones. Coupled with the industry's active investment in research and development and the adoption of large-scale production equipment, the quality of liquid crystal displays has been continuously improved, and the price has continued to decline, which has also rapidly expanded the application fields of liquid crystal displays.

Please refer to Figure 1, which shows the circuit structure of a unit pixel in a liquid crystal display. The unit pixel uses a thin film transistor 10 as a switch. Wherein, the gate of the thin film transistor 10 is connected to the scan line, the source is connected to the data line, and the drain is respectively connected to the storage capacitor Cst and the pixel electrode. When the scanning signal turns on the thin film transistor 10 , the data signal of the source can be transmitted to the pixel electrode through the drain terminal, and applied to the liquid crystal layer 12 to generate a desired image.

In general, impurities such as ionic charges are often left on the surface of the liquid crystal layer or alignment layer due to the liquid crystal material produced or the related manufacturing process of the liquid crystal display. Therefore, when the DC voltage on both sides of the liquid crystal layer is applied for a period of time, the ionic charges in the liquid crystal layer will be attracted by high and low potentials, and accumulate on the surface of the alignment layer on both sides of the liquid crystal layer respectively. Once the DC voltage applied to both sides of the liquid crystal layer is removed, the ionic charges accumulated on the surface of the alignment layer will continue to generate a residual internal DC voltage in the liquid crystal layer, causing serious image sticking problems.

In order to solve the image sticking problem caused by driving the liquid crystal display with a DC voltage, the current liquid crystal display is driven with an AC voltage. However, it is worth noting that due to the influence of parasitic capacitance and coupling capacitance in the unit pixel, when an AC voltage is used to drive the liquid crystal display, a DC voltage will still be generated at both ends of the liquid crystal layer. Please refer to FIG. 2 , which shows the voltage signal waveforms received by each electrode of the thin film transistor 10 in a unit pixel. Wherein, when the scanning signal Vg received by the gate terminal is a high potential signal Vgh, the thin film transistor 10 can be turned on; otherwise, when the scanning signal Vg is a low potential signal Vg1, the thin film transistor 10 can be turned off. Since the AC voltage is used for driving, the data signal written from the source terminal will show a phenomenon of polarity inversion as the scan signal Vg switches the thin film transistor 10 .

However, it should be pointed out that due to the influence of the parasitic capacitance Cgd between the gate and the drain, the auxiliary capacitance Cst, and the liquid crystal layer capacitance Clc, the data signal Vdata transmitted to the drain terminal will have a magnitude of ΔV(Cgd, Cst , Clc) potential shift. As shown in FIG. 2 , no matter what the polarity of the data signal Vs written at the source terminal is, the potential of the data signal Vdata transmitted at the drain terminal will drop by ΔV' and produce the effect of applying a DC voltage to the unit pixel. Especially for data signals with different gray scales, the magnitudes of the potential shifts ΔV are also different, resulting in different magnitudes of the imported DC voltages.

Please refer to FIG. 3 , which shows potential shifts generated by AC voltage signals with different gray scales. Taking a data signal with 256 gray levels as an example, signal waveforms of the 0th, 63rd, 127th, 191st and 255th gray levels are respectively displayed.

It can be clearly seen from the figure that due to the influence of the above-mentioned potential shift ΔV, except for the 127th gray scale, the data signals of other gray scales all present asymmetrical waveforms on both sides of the positive and negative sides, resulting in a DC voltage in the liquid crystal layer. bias effect. In order to solve this problem, in the current display driver design, a gamma correction (Gamma correction) circuit is added when transmitting the new data number Vdata to adjust the extra compensation voltage signal for each gray scale, so as to input The AC data signal for potential adjustment.

As shown in FIG. 3, compared with the original voltage level Vcdc (that is, the signal level of the common electrode located on the other side of the liquid crystal layer and opposite to the above-mentioned pixel electrode), the provided data signal Vdata=Vcdc±V( 0)+V'(0), wherein V(0) is the data signal of the 0th order, and V'(0) is the compensation voltage signal of the 0th order. In this way, the level of the common electrode (common electrode) can be adjusted by the gamma correction voltage V'(0), so that the DC level of the 0th stage becomes Vcdc+V'(0), effectively avoiding the residual DC voltage Impact. In addition, as mentioned above, since each different gray scale will produce a different magnitude of potential shift ΔV, the used gamma correction voltage signals V'(0), V'(63), V'(191), V'(255) is also different. Moreover, for example, the data signal of the 127th level does not require an additional gamma correction term because there is no potential shift.

However, it is worth noting that in order to improve the imaging performance of the display, in the current panel design, the electrodes or alignment layers located on both sides of the liquid crystal layer are often made of different materials or made into different geometric shapes. Typical structures, such as reflective liquid crystal display (RLCD; Reflective Liquid Crystal Display), multi-area vertical alignment liquid crystal display (MVA; Multi-Domain Vertical Alignment), protrusion-slit type liquid crystal display (Protrusion-slit type), or hybrid Alignment liquid crystal display (hybrid-aligned nematic, HAN), etc.. The materials of the electrode-alignment layer on the opposite sides are often different, and the geometric shapes of the electrodes on both sides are also asymmetrical, so the materials on both sides of the liquid crystal contain ions The trapping ratios of the electric materials are not the same, which makes the above-mentioned "DC sticking" and "image sticking" worse. Therefore, how to effectively solve the above problems has become an extremely important subject in the current liquid crystal display manufacturing process.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method that can compensate the potential shift of the data voltage signal due to the parasitic capacitance and coupling capacitance of the pixel unit and can compensate for the difference between the pixel electrode and the common electrode in view of the above-mentioned deficiencies in the prior art. The driving and data voltage signal adjustment method of the active matrix liquid crystal display with the potential shift generated by the asymmetrical material or geometric shape.

The driving and data voltage signal adjustment method of the active matrix liquid crystal display provided by the present invention is realized by the following technical solutions.

A driving method for an active matrix liquid crystal display, wherein the liquid crystal display has an array of pixel units, and each of the pixel units includes a pixel electrode, a common electrode corresponding to the pixel electrode, and a common electrode located between the pixel electrode and the common electrode. The liquid crystal layer between the electrodes is characterized in that it comprises the following steps:

Applying a data voltage signal to the pixel electrode, wherein the data voltage signal is an AC voltage signal V(n) of a specific gray scale:

While applying the AC voltage signal, apply a first compensation voltage signal V'(n) to the pixel electrode, wherein the first compensation voltage signal V'(n) varies with the specific grayscale AC voltage signal, used to compensate the potential shift of the data voltage signal due to the parasitic capacitance and coupling capacitance of the pixel unit; and

While applying the AC voltage signal, apply a second compensation voltage signal Vasy(n) to the pixel electrode, wherein the second compensation voltage signal Vasy(n) varies with the specific grayscale AC voltage signal for Compensating the potential offset generated by the material or geometry asymmetry between the pixel electrode and the common electrode.

In addition to the above-mentioned necessary technical features, the following technical content may also be added during the specific implementation process:

There are n+1 first compensation voltage signals V'(n), which can be divided into V'(0), V'(1), V'(2)...V'( n), wherein when the above-mentioned V'(0) is the highest voltage gray scale, and satisfy 500mV>V'(0)>V'(1)>...>V'((n-1)/2)= 0>V'(n-1)>V'(n)>-500mV.

There are n+1 second compensation voltage signals, and they can be classified into Vasy(0), Vasy(1), Vasy(2)...Vasy(n) according to different gray scales.

The above-mentioned second compensation voltage signal satisfies 500mV>Va sy(0)>Va sy(1)>...>Va sy(n-1)>Vasy(n)>0.

The above-mentioned second compensation voltage signal satisfies -500mV<Vasy(0)<Vasy(1)<...<Vasy(n-1)<Vasy(n)<0.

The present invention also provides a method for adjusting data voltage signals of an active matrix liquid crystal display to prevent image sticking in the liquid crystal display, wherein the liquid crystal display has an array of pixel units, and each pixel unit includes a pixel electrode, The common electrode corresponding to the pixel electrode and the liquid crystal layer between the pixel electrode and the common electrode are characterized by comprising the following steps:

applying an AC data voltage signal V(n) with a specific gray scale to the pixel electrode; and

Adding a compensation voltage signal Vasy(n) to the AC data voltage signal V(n), wherein the compensation voltage signal Vasy(n) corresponds to the specific gray scale, and is used to compensate for the difference between the pixel electrode and the common electrode. Potential shift due to material or geometric asymmetry.

The data voltage signal adjustment method of the active matrix liquid crystal display provided by the present invention, in addition to the above-mentioned necessary technical features, in the specific implementation process, the following technical content can also be supplemented:

It further includes the following steps:

Adding the AC data voltage signal to the additional compensation voltage signal V'(n) for each gray scale adjusted by the gamma correction circuit, wherein the gamma correction voltage signal V'(n) corresponds to the specific gray scale for The potential offset of the data voltage signal due to the parasitic capacitance and the coupling capacitance of the pixel unit is compensated.

There are n+1 gamma correction voltage signals V'(n), which can be divided into V'(0), V'(1), V'(2)...V'( n), and when the above-mentioned V'(0) is the highest voltage gray scale and V'(n) is the lowest voltage gray scale, 500mV>V'(0)>V'(1)>...>V' ((n-1)/2)=0>V'(n-1)>V'(n)>-500mV.

There are n+1 compensation voltage signals above, which can be divided into Vasy(0), Vasy(1), Vasy(2)...Vasy(n) according to different gray scales, and satisfy 500mV>Vasy(0) >Vasy(1)>...>Vasy(n-1)>Vasy(n)>0.

There are n+1 compensation voltage signals above, which can be divided into Vasy(0), Vasy(1), Vasy(2)...Vasy(n) according to different gray scales, and satisfy -500mV<Vasy (0)<Vasy(1)<...<Vasy(n-1)<Vasy(n)<0.

The invention discloses a driving method of an active matrix liquid crystal display. Wherein, the liquid crystal display has an array of pixel units, and each pixel unit includes a pixel electrode, a corresponding common electrode, and a liquid crystal layer between the two electrodes. The method at least includes the following steps. Firstly, a data voltage signal is applied to the pixel electrode. The data voltage signal is an AC voltage signal V(n) of a specific gray scale (nth level). While applying the AC voltage signal, the first compensation voltage signal V'(n) is applied to the pixel electrode. Wherein, the first compensation voltage signal V'(n) varies with the specific grayscale AC voltage signal, and is used to compensate the potential shift of the data voltage signal due to the parasitic capacitance and the coupling capacitance of the pixel unit. Furthermore, while applying the AC voltage signal, the second compensation voltage signal Vasy(n) is applied to the pixel electrode. The second compensation voltage signal Vasy(n) varies with the specific grayscale AC voltage signal, and is used for compensating the potential shift caused by the asymmetry of material or geometric shape between the pixel electrode and the common electrode.

The data voltage signal V(n) can be divided into n+1 gray scales V(0), V(1), V(2)...V(n) according to different gray scales. As for the first compensation voltage signal V'(n), there are also n+1 signals, which are divided into V'(0), V'(1), V'(2)...V'(n ). When the 0th level is the highest voltage grayscale and the nth level is the lowest voltage grayscale, V'(0)>V'(1)>...>V'((n-1)/2)= 0>V'(n-1)>V'(n), and V'(0)<500mV and V'(n)>-500mV.

There are also n+1 second compensation voltage signals, which can be classified into Vasy(0), Vasy(1), Vasy(2)...Vasy(n) according to different gray scales. Wherein Vasy(0)>Vasy(1)>...>Vasy(n-1)>Vasy(n)>0. , then Vasy(0)<500mV.

On the contrary, when Vasy(0)<Vasy(1)<...<Vasy(n-1)<Vasy(n)<0, then Vasy(0)>-500mV.

The advantages of the present invention are:

The driving method of the active-matrix liquid crystal display provided by the present invention considers the asymmetry of the structure or material of the electrodes on both sides of the liquid crystal layer (that is, the pixel electrode and the common electrode), and uses the second compensation voltage signal Vasy to reduce the Therefore, it can be applied to reflective liquid crystal display (RLCD; Reflective Liquid Crystal Display), multi-area vertical alignment liquid crystal display (MVA; Multi-Domain Vertical Alignment), protrusion-slit liquid crystal display (Protrusion- slit type), or hybrid-alignednematic (HAN), etc....the opposite sides of the electrode-alignment layer material or a liquid crystal display with asymmetric geometry to effectively solve the problem caused by the accumulation of interface charges Residual DC voltage problem.

Through the detailed description of the following embodiments combined with the accompanying drawings, the above contents and many advantages of the present invention can be easily understood.

Description of drawings

Figure 1 shows the circuit structure of a unit pixel in a liquid crystal display.

Figure 2 shows the voltage signal waveforms received by each electrode of the thin film transistor in a unit pixel.

FIG. 3 shows the situation of potential shifts generated by AC voltage signals of different gray scales in a traditional liquid crystal display.

FIG. 4 shows the situation of the potential shift generated by the AC voltage signals of different gray scales of the liquid crystal display in the present invention.

FIG. 5 shows the situation of measuring the residual DC voltage after applying a DC bias voltage to the liquid crystal layer for one hour in the present invention. and

FIG. 6 shows the measured residual DC voltage when positive and negative DC voltages are applied to the liquid crystal layer with different electrode materials on both sides in the present invention.

Detailed ways

The invention provides a driving method of an active matrix liquid crystal display, wherein the liquid crystal display has an array of pixel units, and each pixel unit includes a pixel electrode, a common electrode corresponding to the pixel electrode, and an electrode located between the pixel electrode and the common electrode. the liquid crystal layer. According to the method of the present invention, when applying a data voltage signal to the pixel electrode, first provide an AC voltage signal V(n) of a specific gray scale. Taking the AC voltage signal of 256 gray levels as an example, the voltage signals of each gray level are V(0), V(53), V(127), V(191) and V(255) shown in Figure 4 , showing a trapezoidal decreasing trend. That is, the 0th level here is the highest voltage gray level, and the 255th level is the lowest voltage gray level.

It should be particularly pointed out that since the two sides of the liquid crystal layer are the pixel electrode (pixel electrode) and the common electrode (common electrode), and the common signal (common signal) on the common electrode has a DC potential of Vcdc, so The base level on the pixel electrode is also set to Vcdc, as shown in FIG. 4 .

When the data voltage Vdata is applied to the pixel electrode of the unit pixel, a voltage signal with a magnitude of Vcdc±V(n) is provided to generate an image effect of the nth gray scale. However, as mentioned above, in the pixel unit, the parasitic capacitance Cgd will be generated between the gate and the drain of the thin film transistor, and this parasitic capacitance Cgd will be coupled with the auxiliary capacitance Cst and the liquid crystal layer capacitance Clc, resulting in the introduction of additional DC voltage , therefore, the first compensation voltage signal V′(n) is applied to the pixel electrode at the same time as the gray scale voltage signal is applied. Wherein, since the first compensation voltage signal required by the AC voltage signal of each gray scale is also different, the first compensation voltage signal V'(n) will change with different gray scales, so as to correct the parasitic capacitance and coupling of the pixel unit. The potential shift produced by the capacitor.

Referring to FIG. 4 , since the potential shift generated by the 0th-level AC voltage signal of the highest voltage gray scale is the most serious, the required first compensation voltage signal V'(0) is also the largest. Moreover, since the imported DC voltage is superimposed on the level Vcdc, the basic voltage level will be pulled up, so V'(0) here is a negative value, so as to adjust the data signal level of the pixel electrode downward V'(0). Similarly, for the 63rd order AC voltage signal, its basic level is also high, so the required first compensation voltage signal V'(63) is also negative, so as to lower the basic level. As for the 191st-order and 255th-order AC voltage signals, since the introduced DC voltage gray reduces the basic level, the applied first compensation voltage signal V'(191) and V'(255 ) are all positive values, so that the basic levels of the two gray scales can be adjusted upward.

In other words, when the above-mentioned gray scale voltage signals have n+1 numbers and are expressed as V(0), V(1), V(2)...v(n), the first compensation voltage signal also has n+1 1, and can be divided into V'(0), V'(1), V'(2)...V'(n) according to different gray scales. Moreover, when V(0) is the highest gray-scale voltage signal and V(n) represents the smallest gray-scale voltage signal, the first compensation voltage signal will satisfy V'(0)>V'(1)>. ..>V'((n-1)/2)=0>V'(n-1)>V'(n). Taking the voltage signal of 256 gray levels as an example, refer to FIG. 4 , where V'(0)>V'(63)>V'(127)=0>V'(191)>V'(255).

In addition to compensating for the DC voltage introduced by the parasitic capacitance and coupling capacitance of the pixel unit, the pixel electrode and the common electrode located on both sides of the liquid crystal layer will also affect the liquid crystal layer due to the asymmetry of the shape or the similarity and difference of the materials used. The ionic charges in the ions generate different capture rates and lead to the introduction of DC voltage. Therefore, while applying the grayscale voltage signal, a second compensation voltage signal Vasy(n) is applied to the pixel electrode. Wherein, the second compensation voltage signal Vasy(n) also varies with each gray scale voltage signal to compensate for the above-mentioned potential shift caused by the asymmetry of the electrode material or electrode geometry.

In a preferred embodiment, when there are n+1 gray scale voltage signals, and they are expressed as V(0), V(1), V(2)...V(n), the second compensation voltage signal There are also n+1 ones, which can be classified into Vasy(0), Vasy(1), Vasy(2)...Vasy(n) according to different gray scales.

When V(0) is the highest gray-scale voltage signal, and V(n) represents the smallest gray-scale voltage signal, the second compensation voltage signal will satisfy Vasy(0)>Vasy(1)>...>Vasy( (n-1)/2)>...>Vasy(n-1)>Vasy(n). Taking the voltage signal of 256 gray scales as an example, referring to FIG. 4 , Vasy(0)>Vasy(63)>Vasy(127)>Vasy(191)>Vasy(255)>0.

It should be noted that, in the above-mentioned embodiment, the applied second compensation voltage signals Vasy(n) are all greater than 0, so as to perform offset adjustment when the DC voltage level is low. However, for the situation that the DC voltage level is generally high, the applied second compensation voltage signals Vasy(n) can also be all smaller than 0. At this time, when V(0) is the highest gray-scale voltage signal and V(n) represents the smallest gray-scale voltage signal, the second compensation voltage signal can satisfy Vasy(0)<Vasy(1)<... <Vasy((n-1)/2)<...<Vasy(n-1)<Vasy(n)<0. Taking the voltage signal of 256 gray scales as an example, Vasy(0)<Vasy(61)<Vasy(127)<Vasy(191)<Vasy(255)<0.

The invention also provides a method for determining the magnitude of the second compensation voltage signal Vasy(n). Please refer to FIG. 5 , firstly, the residual DC bias voltage can be measured for the liquid crystal layer. The method of measurement is to first apply a DC voltage of 5 volts to the liquid crystal layer for about 60 minutes, and then measure the residual DC bias voltage on the liquid crystal layer after removing the DC voltage for 1 second. Please refer to Figure 6. When the electrode materials on both sides of the liquid crystal layer are different, namely indium tin oxide (ITO) and aluminum material (Al), if a +5 volt DC power supply is applied (i.e., ITO is the positive electrode and the aluminum material is Negative electrode), then after the DC voltage is applied for 60 minutes, a high residual DC bias voltage of about 3.5 volts will be generated (the two sets of test data are lines a and b in the figure). Conversely, when a -5 volt DC power supply is applied (that is, indium tin oxide is the negative electrode and the aluminum material is the positive electrode), a low residual DC bias voltage of about 1.5 volts will be generated (the two sets of test data are lines c and d).

It is worth noting that when measuring the residual DC bias voltage, as time increases, there will be a difference of about 3.0 volts in the residual DC voltage caused by applying +5 volts and applying -5 volts respectively at about 27 minutes . With this difference, the magnitude of the second compensation voltage Vasy(n) can be estimated more accurately.

Taking the typical normally white mode as an example, the difference between the Feed through Voltage (Feed through Voltage) between the 0th gray scale (black) and the 255th gray scale (white) of the higher voltage is about It is 0.5-1.0 volts, so it can take half of this voltage value, about 0.25-0.50 volts, as the DC bias of the 0th and 255th grayscale screens of the liquid crystal display with asymmetrical electrode materials or geometric shapes on both sides. absolute value of pressure. From this, you can get:

(3V/5V)*0.25V-0.5V＝150mV-300mV

Among them, 3V is the maximum difference between the residual DC bias voltage when +5V and -5V are applied in the above test; as for 5V, it is the DC voltage continuously applied for 1 hour. Thus, for a typical thin film transistor liquid crystal display, the residual voltage difference between the 0th-order image and the 255th-order image is about 150mV-300mV.

However, if the duration of the DC bias voltage is considered to be 10 hours, and the structure on both sides of the pixel electrode and the common electrode is more asymmetric (that is, considering the difference in materials and geometric shapes), the residual DC bias voltage should be larger . Therefore, the limit value of the residual DC bias voltage can be taken as high as 500mV. That is, when considering the second compensation voltage signal, Vasy<500mV.

In a preferred embodiment, when the first compensation voltage signal satisfies V'(0)>V'(62)>V'(127)=0>V'(191)>V'(255), V '(0)<500mV such that V'(255)>-500mV. In addition, when the second compensation voltage signal satisfies Vasy(0)>Vasy(63)>Vasy(127)>Vasy(191)>Vay(255)>0, Vasy(0)<500mV. On the contrary, when the second compensation voltage signal satisfies Vasy(0)<Vasy(63)<Vasy(127)<Vasy(191)<Vasy(255)<0, then Vasy(0)>-500mV.

Although the present invention has been described above with preferred embodiments, it is not intended to limit the spirit and entity of the present invention, and is only limited to the above embodiments. Those skilled in the art can easily understand and use other elements or methods to produce the same effect. Therefore, modifications made without departing from the spirit and scope of the present invention should be included in the scope of the described claims.

Claims (9)

1. A driving method for an active-matrix liquid crystal display, wherein the liquid crystal display has an array of pixel units, and each of the pixel units includes a pixel electrode, a common electrode corresponding to the pixel electrode, and an electrode located between the pixel electrode and the pixel electrode. The liquid crystal layer between the common electrodes is characterized in that it comprises the following steps: Applying a data voltage signal to the pixel electrode, wherein the data voltage signal is an AC voltage signal V(n) of a specific gray scale: While applying the AC voltage signal, apply a first compensation voltage signal V'(n) to the pixel electrode, wherein the first compensation voltage signal V'(n) varies with the specific grayscale AC voltage signal, used to compensate the potential shift of the data voltage signal due to the parasitic capacitance and coupling capacitance of the pixel unit; and While applying the AC voltage signal, apply a second compensation voltage signal Vasy(n) to the pixel electrode, wherein the second compensation voltage signal Vasy(n) varies with the specific grayscale AC voltage signal for Compensate the potential offset caused by the material or geometrical asymmetry between the pixel electrode and the common electrode, and the above-mentioned second compensation voltage signal has n+1, and can be divided into Vasy (0 ), Vasy(1), Vasy(2)...Vasy(n). 2. the driving method of active matrix type liquid crystal display according to claim 1, it is characterized in that: above-mentioned first compensation voltage signal V ' (n) has n+1, and can be distinguished into according to different gray-scale sizes V'(0), V'(1), V'(2)...V'(n), when the above V'(0) is the highest voltage gray scale, and satisfy 500mV>V'(0) >V'(1)>...>V'((n-1)/2)=0>V'(n-1)>V'(n)>-500mV. 3. The driving method of an active-matrix liquid crystal display according to claim 2, wherein the above-mentioned second compensation voltage signal satisfies 500mV>Vasy(0)>Vasy(1)>...>Vasy(n- 1)>Vasy(n)>0. 4. The driving method of an active-matrix liquid crystal display according to claim 2, wherein the above-mentioned second compensation voltage signal satisfies -500mV<Vasy(0)<Vasy(1)<...<Vasy(n -1)<Vasy(n)<0. 5. A data voltage signal adjustment method for an active matrix liquid crystal display, used to prevent image retention from occurring in the liquid crystal display, wherein the liquid crystal display has an array of pixel units, and each of the pixel units includes a pixel electrode corresponding to The common electrode of the pixel electrode and the liquid crystal layer between the pixel electrode and the common electrode are characterized by comprising the following steps: applying an AC data voltage signal V(n) with a specific gray scale to the pixel electrode; and Adding a compensation voltage signal Vasy(n) to the AC data voltage signal V(n), wherein the compensation voltage signal Vasy(n) corresponds to the specific gray scale, and is used to compensate for the difference between the pixel electrode and the common electrode. Potential offset caused by material or geometric asymmetry, and the above-mentioned compensation voltage signal has n+1, and can be divided into Vasy(0), Vasy(1), Vasy(2).. .Vasy(n). 6. the data voltage signal adjustment method of active matrix liquid crystal display according to claim 5, it is characterized in that: further comprise the following steps: Adding the AC data voltage signal to the additional compensation voltage signal V'(n) for each gray scale adjusted by the gamma correction circuit, wherein the gamma correction voltage signal V'(n) corresponds to the specific gray scale for The potential offset of the data voltage signal due to the parasitic capacitance and the coupling capacitance of the pixel unit is compensated. 7. The data voltage signal adjustment method of an active-matrix liquid crystal display according to claim 5, characterized in that: the above-mentioned gamma correction voltage signal V'(n) has n+1, and can be adjusted according to the size of different gray scales And it is divided into V'(0), V'(1), V'(2)...V'(n), and when the above V'(0) is the highest voltage gray level and V'(n) is the lowest In voltage gray scale, 500mV>V'(0)>V'(1)>...>V'((n-1)/2)=0>V'(n-1)>V'(n )>-500mV. 8. The data voltage signal adjustment method of an active-matrix liquid crystal display according to claim 5, wherein said compensation voltage signal satisfies 500mV>Vasy(0)>Vasy(1)>...>Vasy(n -1)>Vasy(n)>0. 9. The data voltage signal adjustment method of an active-matrix liquid crystal display according to claim 5, wherein said compensation voltage signal satisfies -500mV<Vasy(0)<Vasy(1)<...<Vasy( n-1)<Vasy(n)<0.

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