JPH0634941A - Driving method for active matrix type liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain the active matrix type liquid crystal display device which generates no smear and is free from deterioration in display picture quality due to smear. CONSTITUTION:The active matrix type liquid crystal display device has a matrix substrate equipped with many parallel-arranged scanning lines 1, many parallel-arranged signal lines 2 crossing the scanning lines 1 at right angles, thin films transistors(TR) 3 and liquid crystal cells 4 arranged at the respective intersections of the scanning lines 1 and signal lines 2, and a scanning-side driving circuit and a signal-side driving circuit coupled with the matrix substrate respectively. When this display device is driven. a display signal (drain voltage) VD applied to each signal line 1 in the selection time (1H) of each scanning line changes from the positive polarity to the negative polarity, and consequently variation in the hold voltage of the liquid crystal cell 4 at the end of the selection period (1H) of each scanning line is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving an active matrix type liquid crystal display device, and more particularly to a method for driving an active matrix type liquid crystal display device for improving the display image quality of the active matrix type liquid crystal display device. .

[0002]

2. Description of the Related Art Conventionally, a known active matrix type liquid crystal display device includes a large number of scanning lines arranged in parallel, a large number of signal lines arranged in parallel in a direction orthogonal to the scanning lines, the scanning lines and the signals. Thin film transistors (hereinafter referred to as T
FT) and a liquid crystal cell, and a scanning side driving circuit is connected to each scanning line of this matrix substrate, and a signal side driving circuit is connected to each signal line of the matrix substrate. It is configured. Then, in order to drive and display this active matrix type liquid crystal display device, the scanning side driving circuit sequentially applies a scanning signal (gate voltage) to each scanning line, and at the same time, the signal side driving circuit Voltage) is sequentially applied to each signal line so that a desired liquid crystal display is performed on the matrix substrate.

By the way, FIG. 8A is a partial configuration diagram showing a configuration of one pixel portion in the known active matrix liquid crystal display device, and FIG. 8B is a signal for driving the one pixel portion. FIG. 6 is a signal waveform diagram showing the supply timing of

In FIG. 10A, 50 is a scanning line, 51 is a signal line, 52 is a TFT, and 83 is a liquid crystal cell.

A signal line 51 is arranged orthogonal to the scanning line 50, and a TFT 52 and a liquid crystal cell 53 are arranged at the intersection of the scanning line 50 and the signal line 51. A gate of the TFT 52 is connected to the scanning line 50, a drain thereof is connected to the signal line 51, and a liquid crystal cell 53 is connected between its source and a counter substrate voltage generating circuit (not shown). In this case, the TFT 52 and the liquid crystal cell 53 form one pixel portion.

The driving operation of this one pixel portion is shown in FIG.
(B) will be described together.

During the selection time (1H) of the first scan line, a positive gate voltage (scan signal) V _G is supplied to the scan line 50, and the TFT 52 is applied by applying the gate voltage V _G. Turns on. Further, during the selection time (1H) of this one scanning line, the positive polarity (or the negative polarity)
The drain voltage (display signal) V _D of the TFT is supplied to the signal line 51, and the drain voltage V _D of the TFT is in the ON state.
Liquid crystal cell 53 connected to its source through 52
Is supplied to one of the electrodes. At this time, since the counter electrode voltage Vcom having the negative polarity (or the positive polarity) is supplied to the other electrode of the liquid crystal cell 53 during the selection time (1H) of one scan line, the voltage between both electrodes of the liquid crystal cell 53 is increased. Is applied with a difference voltage between the drain voltage V _D and the counter substrate voltage Vcom, and liquid crystal display corresponding to the difference voltage is performed.

Then, the selection time (1
H), the scanning line 5 of the positive gate voltage V _G
The supply to 0 is stopped and the TFT 52 is turned off.
At this time, the negative drain voltage V _D changes to the signal line 51.
The counter substrate voltage Vcom of positive polarity is supplied to the other electrode of the liquid crystal cell 53.
Is in the off state, the voltage state between both electrodes of the liquid crystal cell 53 does not change at all, and the liquid crystal cell 53 still holds the magnitude of the difference voltage and performs display corresponding thereto. Then, in the above-mentioned state, after the selection time (1H) of one scanning line is repeated several times, the scanning line 5
It is maintained until the positive gate voltage V _G is supplied to 0.

Next, when the TFT 52 is turned on by the supply of the gate voltage V _G of the positive polarity, the drain voltage V _D supplied to the signal line 51 at that time is applied to the liquid crystal cell 53, Instead of the differential voltage held in the liquid crystal cell 53 until then, the differential voltage between the drain voltage V _D and the counter substrate voltage Vcom at that time is determined by the liquid crystal cell 53.
The above operation is repeated.

Although only one pixel portion is shown in FIG. 8 (a), exactly the same operation is performed at the same time for the other pixel portions, so that a desired pixel is formed on the entire matrix substrate. One image is displayed at any time.

[0011]

However, in the above-mentioned active matrix type liquid crystal display device, the TFT 52 and the liquid crystal cell 53 which constitute each pixel portion are the same as those shown in FIG.
As shown by the dotted line in (a), since the drain-source stray capacitance 54, the intrinsic capacitance 55, and the storage capacitance 56 are included, the inter-electrode voltage (the difference voltage) of the liquid crystal cell 53 even when the TFT 52 is off. However, it slightly changes depending on the magnitude and polarity of the drain voltage V _D to be applied to other pixels supplied to the signal line 51, and the display state of the liquid crystal cell 53 also slightly changes according to the change, so-called. , Smears will start to occur. Further, this smear occurs relatively often especially during half-tone display, and the above-mentioned active matrix type liquid crystal display device has a problem that the display image quality is deteriorated due to the occurrence of smear. There is.

The present invention eliminates such a problem, and an object thereof is to provide an active matrix type liquid crystal display device in which smear does not occur and display image quality is not deteriorated. is there.

[0013]

In order to achieve the above object, the present invention provides a number of scanning lines arranged in parallel, a number of signal lines arranged in parallel orthogonal to the scanning lines, and the scanning lines and the signal lines. In a driving method of an active matrix type liquid crystal display device having a matrix substrate having thin film transistors and liquid crystal cells arranged at each intersection, and a scanning side driving circuit and a signal side driving circuit,
Means for applying a display signal having a positive polarity and a negative polarity to each signal line within the selection time of each one scanning line is provided.

[0014]

According to the above-mentioned means, the display signal having the positive polarity and the negative polarity is supplied to each signal line within the selection time (1H) of each one scanning line. In this case, the non-selected liquid crystal cell is also supplied with a small part of the display signal having the positive polarity and the negative polarity through the drain-source stray capacitance of the TFT in the off state by the means also. The voltage between the electrodes of the non-selected liquid crystal cell is slightly changed, but the direction of the change with respect to the display signal of the positive polarity and the change with respect to the display signal of the negative polarity within the selection time (1H) of each scanning line. Since the directions are opposite to each other, the selection time (1
With each H) the fluctuations become substantially offset.

As described above, in the non-selected liquid crystal cell, since the effective voltage of the inter-electrode voltage hardly changes, smear does not occur, and the active image is not deteriorated due to the occurrence of smear. A matrix type liquid crystal display device can be obtained.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

1A and 1B show a first embodiment of a method for driving an active matrix type liquid crystal display device according to the present invention. FIG. 1A is a partial configuration diagram showing the configuration of one pixel portion, and FIG. FIG. 4 is a signal waveform diagram showing a drive signal supply timing.

In FIG. 1A, 1 is a scanning line, 2 is
Is a signal line, 3 is a TFT, 4 is a liquid crystal cell, and 5 is a TFT
3 is a drain-source stray capacitance, 6 is an intrinsic capacitance of the liquid crystal cell 4, and 7 is a storage capacitance of the liquid crystal cell 4.

In FIG. 1B, V _G is a scanning signal (gate voltage) supplied to the scanning line 1, V _D is a display signal (drain voltage) supplied to the signal line 2, and V _D
C is the center voltage of the drain voltage V _D , 1H is the selection time for one scanning line, and 1 / F is the frame synchronization frequency.

A signal line 2 is arranged orthogonal to the scanning line 1, and a TFT 3 and a liquid crystal cell 4 are connected and arranged at an intersection of the scanning line 1 and the signal line 2. TFT3
, The gate is scan line 1, the drain is signal line 2,
The source is connected to one electrode of the liquid crystal cell 4,
The other electrode of the liquid crystal cell 4 is connected to a counter substrate voltage generating circuit (not shown). Here, the TFT 3 and the liquid crystal cell 4 form one pixel portion.

In the driving method of this embodiment, the following operation is performed.

First, at time t ₀ , when the selection time (1H) of the first scan line for selecting the liquid crystal cell 4 is reached, the positive gate voltage (scan signal) V is applied to the scan line 1.
_G is applied, and the TFT 3 is turned on by its gate voltage V _G. At this time, the drain voltage (display signal) V that has a negative polarity first and then has a positive polarity on the signal line 2
_D is applied, and its drain voltage V _D is supplied to the liquid crystal cell 4 through the TFT 3 in the ON state. That is, the liquid crystal cell 4 is first supplied with the negative drain voltage V _D for a relatively short period of time, and then is supplied with the positive drain voltage V _D for a relatively long period of time. The absolute level (peak value) of sex is the same.

Next, at time t ₁ , when the selection time (1H) of the first scan line ends and the selection time (1H) of the next scan line in which the liquid crystal cell 4 enters the non-selected state is reached, the positive electrode Of the positive gate voltage V _{G to} the scan line 1 is stopped, and the TFT 3 is turned off. In this case, in the liquid crystal cell 4, the electrode on the side of the TFT 3 (hereinafter, a point on this electrode is referred to as point A) is electrically isolated, so that the point A is at the time when the TFT 3 is turned off. It becomes fixed to the voltage V _S. The voltage V _{S at the} point A has a time t ₂ at which the selection time (1H) of the next one scanning line ends, and a time t _n after the selection time (1H) of several subsequent scanning lines. (Where n is an integer of 3 or more), it functions as a display effective voltage that determines the display state of the liquid crystal cell 4 until the liquid crystal cell 4 is selected again.

Also in this case, since the point A is electrically isolated from other circuit parts by the turning off of the TFT 3 while the TFT 3 is off, the display effective voltage V _{S at the} point A is theoretical. However, since the drain-source stray capacitance 5 in the TFT 3 and the intrinsic capacitance 6 and the storage capacitance 7 in the liquid crystal cell 4 are present, the liquid crystal cell 4 is not selected. From the time t ₁ to the time t _{n in the} state,
The drain voltage V _D applied to the other liquid crystal cells 4 sequentially applied to the signal line 2 is divided by the drain-source stray capacitance 5 and the total capacitance of the intrinsic capacitance 6 and the storage capacitance 7, The partial pressure output is applied to the liquid crystal cell 4. That is, since the drain voltage V _D applied to the other liquid crystal cell 4 is superimposed on the display effective voltage V _S at the point A on the electrode of the liquid crystal cell 4 with a minute amplitude, the display effective voltage V _S is The drain voltage V _{D with} a small amplitude varies depending on the magnitude and polarity. Therefore, in the known driving method in which the polarity of the drain voltage V _D is not changed within the selection time (1 H) of each one scanning line, the variation of the display effective voltage V _S is as described above. It becomes relatively large and causes smear on the display screen.

However, in the present embodiment, the drain voltage (display signal) V _D applied to the signal line 2 is set within the selection time (1H) of each one scanning line.
It is configured to have a positive polarity and a negative polarity so that the fluctuation of the display effective voltage V _S is reduced. That is,
As shown in FIG. 1C, the display effective voltage V _S is first affected by the negative drain voltage V _D applied at the beginning of the selection time (1H) of each scanning line, and is first detected. its voltage level successively slightly decreased toward the negative direction, in the respective one scanning line selection period (IH), the drain voltage V _D of the subsequently positive polarity to the application of the negative polarity of the drain voltage V _D Since the voltage level slightly decreased in the negative direction is then gradually increased in the positive direction, the display effect at the end time of the selection time (1H) of each one scanning line. Voltage V
The voltage level of _S depends on the selection time (1
H) up to the initial display effective voltage V _S voltage level,
Alternatively, the voltage returns to a level close to the voltage level. Therefore, the fluctuation of the display effective voltage V _S between the time t ₁ and the time t _n when the liquid crystal cell 4 is in the non-selected state is small to the extent that it has almost no effect on the whole. , Or becomes a value close to zero, smear is not generated on the display screen, and the display image quality can be improved.

Further, even within the selection time (1H) of one scanning line in which the liquid crystal cell 4 is selected, the drain voltage (display signal) V _D is converted from the negative polarity to the positive polarity, and according to the polarity conversion. The voltage at the point A of the liquid crystal cell 4 also has a negative polarity at first and is followed by a process of being converted to a positive polarity, but the selection time (1
The display effective voltage V _S held and fixed at the point A of the liquid crystal cell 4 in (H) is the selection time (1
H), the positive drain voltage V applied at the end of
Because it is _D, wherein as the drain voltage V _D of the negative polarity prior to the positive polarity of the drain voltage V _D is applied, the display effective voltage V _S which is held fixed to the liquid crystal cell 4
It has no effect on the formation action of.

As described above, in this embodiment, the drain voltage (display signal) V _D having positive and negative polarities having different durations is applied within the selection time (1H) of each one scanning line. Therefore, when the liquid crystal cell 4 is not selected, the selection time (1
Since the fluctuation of the display effective voltage V _S of the liquid crystal cell 4 in H) can be substantially suppressed, smear does not occur on the display screen, and the display image quality can be improved.

Next, FIG. 2 shows a second embodiment of the driving method of the active matrix type liquid crystal display device according to the present invention, in which (a) is a partial configuration diagram showing the configuration of one pixel portion, b) is a signal waveform diagram showing the supply timing of the drive signal.

In FIG. 2, the same constituent elements as those shown in FIG. 1 are designated by the same reference numerals, and the same signal elements as those shown in FIG. 1 are designated by the same reference numeral.

The difference between this embodiment and the first embodiment is that in the first embodiment, the drain voltage V _D within the selection time (1H) of each scanning line is In this embodiment, the duration of the negative polarity portion is different, whereas in the present embodiment, the drain voltage V _D within the selection time (1H) of each scan line is the duration of the positive polarity portion and the negative polarity portion. That the times are equal,
That is, the negative polarity portion of the drain voltage V _D is in the first half of the selection time (1H) of each scan line, and the positive polarity portion of the drain voltage V _D is in the second half of the selection time (1H). There is no difference between the present embodiment and the first embodiment in other points.

Since the operation of this embodiment is exactly the same as the operation of the first embodiment described above, the description of the operation of this embodiment will be omitted.

According to this embodiment, no matter what level of drain voltage V _D is applied to the signal line 2,
The voltage at the point A of the liquid crystal cell 4 can be seen as if the center voltage V _C of the drain voltage V _D is apparently applied, so that the display effective voltage V _{S at the} point A hardly changes. It will be zero. Therefore, smear is not generated on the display screen, and the display image quality can be significantly improved.

Next, FIG. 3 shows a third embodiment of the driving method of the active matrix type liquid crystal display device according to the present invention, wherein (a) is a partial configuration diagram showing the configuration of one pixel portion, (B) is a signal waveform diagram showing the supply timing of the drive signal.

In FIG. 3, the same constituent elements as those shown in FIG. 1 are designated by the same reference numerals, and the same signal elements as those shown in FIG. 1 are designated by the same reference numerals.

The difference between this embodiment and the second embodiment is that in the second embodiment, the drain voltage V _D within the selection time (1H) of each scan line is While the durations of the negative polarity portions are equal and the positive polarity portion and the negative polarity portion occur once, in the present embodiment, within the selection time (1H) of each one scanning line. The drain voltage V _D is such that the positive polarity portion and the negative polarity portion each have the same duration, and the positive polarity portion and the negative polarity portion are alternately generated twice, that is, one scanning line for each. Of the drain voltage V _D during the first quadrant of the selection time (1H), and the positive polarity of the drain voltage V _{D during} the second quadrant of the first quadrant. The sex part is a third part that follows the second quarter. Negative portions again the drain voltage V _D is the time of the half portion, the last 4 following the third 4 half
It is configured such that the positive polarity portion of the drain voltage V _D is applied again during the half time, and in other points, there is nothing between the present embodiment and the second embodiment. There is no difference.

Since the operation of this embodiment is exactly the same as the operation of the above-mentioned first or second embodiment, the description of the operation of this embodiment will be omitted.

Also in this embodiment, the same effects as the effects obtained in the second embodiment can be obtained, and the display image quality can be remarkably improved without causing smear on the display screen. It is a thing.

Next, FIG. 4 shows a fourth embodiment of the driving method of the active matrix type liquid crystal display device according to the present invention, in which (a) is a partial configuration diagram showing the configuration of one pixel portion, (B) is a signal waveform diagram showing the supply timing of the drive signal.

In FIG. 4A, the same components as those shown in FIG. 1A are designated by the same reference numerals, and in FIG. 4B, the signal types shown in FIG. The same signal type is given the same reference numeral.

The difference between this embodiment and the first embodiment is that in the first embodiment, the drain voltage V _D within the selection time (1H) of each scanning line is While the durations of the negative polarity portions are different, and the absolute value levels (peak values) of the positive polarity portions and the negative polarity portions are the same, in the present embodiment, each scanning line The drain voltage V _D within the selected time (1H) is common in that the durations of the positive polarity portion and the negative polarity portion are different, but the positive polarity portion and the negative polarity portion have the same duration. The point is selected so that the absolute value level (peak value) of the shorter one is large and the absolute value level (peak value) of the longer duration is small, specifically, for each scanning line. Mark at the beginning of the selection time (1H) And the negative portion of the drain voltage V _D to be pressurized, and the positive portion of the drain voltage V _D applied subsequently, its duration is one-to-n (here, n represents 1
The above values are selected, and the absolute value level (peak value) thereof is selected to be n: 1. In other points, the present embodiment and the first embodiment are different. There is no difference between.

Since the operation of this embodiment is exactly the same as the operation of the above-mentioned first embodiment, the explanation of the operation of this embodiment will also be omitted.

According to this embodiment, the absolute value level (peak value) of the negative polarity portion of the drain voltage V _D which is initially applied within the selection time (1H) of one scanning line is applied subsequently. negative part of the drain voltage absolute value level chosen to be higher by n times than the (peak value) of the positive polarity portion of the V _D, and the duration of the positive polarity portion of the drain voltage V _D drain voltage V _D Since it is selected so as to be n times longer than the duration of, the writing time of the drain voltage V _D to the liquid crystal cell 4 can be sufficiently taken within the selection time (1H) of each one scanning line, and ,
The average value of the drain voltage V _D can be matched with the center voltage V _C thereof. Therefore, in this embodiment,
Similar to the first to third embodiments described above, it is possible to significantly improve the display image quality without generating smear on the display screen, and it is superior to the first to third embodiments described above. The writing characteristic to the liquid crystal cell 4 is obtained,
There is an effect that excellent smear elimination characteristics can be obtained.

Next, FIG. 5 is a block diagram showing an example of the overall configuration of an active matrix type liquid crystal display device to which the driving method of the present invention is applied.

In FIG. 5, 8 is a TFT-LCD (thin film transistor-liquid crystal cell) matrix substrate, 9 is a scanning side driving circuit, 10 is a signal side driving circuit, 11 is a counter substrate voltage generating circuit, and 12 is a display signal polarity reversing circuit. , 13 is a controller, 14 is an image signal source, and the same components as those shown in FIG. 1 are denoted by the same reference numerals.

Then, the TFT-LCD matrix substrate 8
Is connected to the scanning side drive circuit 9 at the end of each scanning side line 1.
However, the signal side drive circuit 10 is connected to the end of the signal line 2, and the return side electrode of each liquid crystal cell 4 in the TFT-LCD matrix substrate 8 is connected to the counter substrate voltage generation circuit 11. A display signal polarity reversing circuit 12 for reversing the polarity of the display signal (drain voltage) V _D for an appropriate time is connected between the image signal source 14 and the signal side driving circuit 9, and the scanning side driving circuit 9 and the signal side driving circuit are driven. The circuit 10, the counter substrate voltage generation circuit 11, and the image signal source 14 are each configured to be controlled by the controller 13.

In the above-mentioned active matrix type liquid crystal display device, the following operations are generally performed.

The display signal generated by the image signal source 14 is obtained, for example, by sampling the original analog scanning image signal, and is composed of a stepwise signal whose voltage level varies stepwise. This staircase signal is
Signal side drive circuit 10 via display signal polarity reversal circuit 12
And a display signal (drain voltage) V that is sequentially supplied to each signal line 2 of the TFT-LCD matrix substrate 8.
Converted to _D. Further, the scanning side drive circuit 9 generates a scanning signal (gate voltage) V _G which is sequentially supplied to the scanning line 1 every selection time (1H) of one scanning line. TF
In the T-LCD matrix substrate 8, by applying the scanning signal (gate voltage) V _G and the display signal (drain voltage) V _D , each liquid crystal cell 4 is sequentially selected as known, and the display signal (drain) is applied to them. The voltage corresponding to the voltage) V _D is accumulated and held, and a display image corresponding to the content of the display signal (drain voltage) V _D can be obtained in the TFT-LCD matrix substrate 8.

In this case, the active matrix type liquid crystal display device supplies each stepwise signal generated by the image signal source 14 to the display signal polarity reversing circuit 12 before supplying it to the signal side drive circuit 10, and the above-mentioned signal is supplied there. Part of each staircase signal,
For example, the first nth of the duration of each step signal
(However, n> 1), reverse the polarity, or
Since the operation of inverting the polarity and multiplying the voltage level (peak value) of that portion by n and the operation of non-inverting the polarity of the remaining period of the period are performed, the output of the signal side drive circuit 10 Each display signal (drain voltage)
V _D is such that there is a portion where the polarity is inverted at the beginning of the selection time (1H) of one scanning line and a portion where the polarity is not inverted after that, and eventually, each signal line 2 is 1 scanning line. Within the selection time (1H), the display signal (drain voltage) V _D having the positive polarity and the negative polarity is applied.

In this active matrix type liquid crystal display device, when the display signal (drain voltage) V _D having a positive polarity and a negative polarity is applied within the selection time (1H) of one scanning line, the above-mentioned first to If the display signal (drain voltage) V _D of the type according to any one of the driving methods of the fourth embodiment is used, as described in the driving method of the first to fourth embodiments, the TFT- LCD matrix substrate 8
In the above, there is an effect that it is possible to display a good image quality without smear.

Although the active matrix type liquid crystal display device has a structure in which the counter substrate voltage generating circuit 11 is connected to the TFT-LCD matrix substrate 7, as is well known, the counter substrate voltage generating circuit 11 is It is not always necessary to use this type of liquid crystal display device.

Next, FIG. 6 shows a fifth embodiment of the driving method of the active matrix type liquid crystal display device according to the present invention, showing an example of the case where the driving means for the AC counter substrate voltage Vcom is added. 4A is a partial configuration diagram showing the configuration of four pixel portions, and FIG. 4B is a signal waveform diagram showing the supply timing of the drive signal.

In FIG. 6, the same components as those shown in FIG. 1 are designated by the same reference numerals, and the same signal types as those shown in FIG. 1 are designated by the same reference numerals. Regarding the components and the signal types, subscripts are attached after the reference numerals according to the arrangement (supply) positions.

For example, in the FET shown in FIG. 6, the upper left one is 3 ₁₁ , the upper right one is 2 ₁₂ , the lower left one is 3 ₂₁ , and the lower right one is 3 _22. , The upper one is shown as 1 ₁ and the lower one is shown as 1 _{2. In} the signal line, the left one is 2 ₁ and the right one is 2 _2.
The same applies to other elements.

The difference between this embodiment and the second embodiment is as follows.

First, in the second embodiment, the drain voltage V _D within the selection time (1H) of one scanning line is such that the negative polarity portion first comes and then the positive polarity portion comes (hereinafter, Is referred to as the first signal format) is continuously supplied within the first frame 1 / F period, and the next frame 1 / F is supplied.
In the period F, the type in which the positive polarity portion first comes and then the negative polarity portion comes (hereinafter, referred to as the second signal type) is continuously supplied, and the next frame 1 / The first and second signal formats are alternately supplied every frame 1 / F period such that the first signal format is supplied again during the F period.

On the other hand, in this embodiment, as the drain voltage V _D within the selection time (1H) of one scanning line, the first signal format is supplied for the selection time (1H) of the first one scanning line. , 1 scan line selection time (1H)
Is supplied with the second signal format, and the selection time (1H) of the next one scanning line is supplied with the first signal format, so that selection of one scanning line is performed within the first frame 1 / F period. The first and second signal types are alternately supplied in the above-mentioned order every time (1H), and at the same time, the negative polarity and the second signal type are supplied when the first signal type is supplied. At times, a positive AC counter substrate voltage Vcom is supplied. Then, in the second frame 1 / F period,
This time, the selection time (1H) of the first scan line is supplied with the second signal format, and the selection time (1H) of the following one scan line is supplied with the first signal format, and the selection time of the next scan line is The selection time (1H) is 1 during this frame 1 / F period such that the second signal format is supplied.
The second and first signal formats are alternately supplied in the above-described order for each scanning line selection time (1H), and at the same time, when the second signal format is supplied, the positive polarity and the first signal format are supplied. At times, a negative AC counter substrate voltage Vcom is supplied. After that, in the third frame 1 / F period, the first frame is again displayed.
The same first signal supply pattern as the frame 1 / F period of
In the fourth frame 1 / F period, the same second signal supply pattern as in the second frame 1 / F period is used.
And the second signal supply pattern is repeated.

The operation of this embodiment is the same as that of the liquid crystal cells 4 _{11 to} 4 _22.
The voltage stored retained between the electrodes, when the liquid crystal cell 4 ₁₁ to 4 ₂₂ is selected, except as determined by the voltage difference between the drain voltage V _D and an AC counter substrate voltage Vcom, the Since the operation is the same as that of the second embodiment, further detailed description will be omitted.

[0058] According to this embodiment, with the polarity for each selection time (1H) of the one scanning line is inverted, the drain voltage V _D to further polarity is inverted every 1 frame 1 / F period
, And the AC counter substrate voltage Vcom are used, it is well known that the liquid crystal cells 4 _{11 to} 4 4 are supplied throughout the entire operation period.
The average value of the applied voltage to ₂₂ can be made almost zero, and the excellent smear removal function can be exhibited, and higher quality image display can be performed.

FIG. 7 shows a sixth embodiment of the driving method of the active matrix type liquid crystal display device according to the present invention, in which another driving means for the AC counter substrate voltage Vcom is added. FIG. 3A is a partial configuration diagram showing a configuration of four pixel portions, and FIG. 3B is a signal waveform diagram showing a drive signal supply timing.

In FIG. 7, the same components as those shown in FIG. 6 are designated by the same reference numerals, and the same signal types as those shown in FIG. 6 are designated by the same reference numerals.

The difference between this embodiment and the fifth embodiment is that in the fifth embodiment, each of the liquid crystal cells 4 _{11 to} 4 _{22 is different.}
The other ends of the storage capacitors 7 _{11 to} 7 ₂₂ are connected to the counter substrate voltage generation circuit 11, and the scanning signal (gate voltage) V _G arrives within the selection time (1H) of one scanning line to be selected. whereas is made of part of sex, in the present embodiment, the other end of the storage capacitor 7 ₁₁ to 7 ₂₂ are connected to the scanning line 1 _{0-1 1} adjacent, and the scanning signal (gate voltage ) V _{G0 to} V _G2 have a positive polarity portion that arrives within the selection time (1H) of one scanning line to be selected, and a negative polarity portion that arrives within the selection time (1H) of the next one scanning line. In other respects, there is no difference between the present embodiment and the fifth embodiment.

The operation of this embodiment is performed in each of the liquid crystal cells 4 _{11 to} 4 _11.
At the selection time (1H) of one scanning line in which ₂₂ is selected, the common electrodes of the intrinsic capacitances 6 _{11 to} 6 ₂₂ of the respective liquid crystal cells 4 _{11 to} 4 _{22 have} a positive AC counter voltage from the counter substrate voltage generating circuit 11. substrate voltage Vcom, the negative polarity scan signal (gate voltage) V _G0 through from the storage capacitor 7 ₁₁ to 7 ₂₂ scan lines 1 ₀ to 1 _1, which is selected immediately before the each liquid crystal cell 4 ₁₁ to 4 ₂₂ V _G2 is supplied to each of the liquid crystal cells 4 _{11 to} 4 ₂₂ , and the electrodes on the side of the TFTs 3 _{11 to} 3 _{22 of the} liquid crystal cells 4 _{11 to} 4 ₂₂ are also positive electrodes from the corresponding signal lines 2 ₁ and 2 ₂ via the corresponding TFTs 3 _{11 to} 3 _22. is sex and the negative polarity of the display signal (drain voltage) V _D1 to V _D2 is applied, as a result, the display signal (drain voltage) of the negative polarity between the amount electrodes of each liquid crystal cell 4 ₁₁ to 4 ₂₂ V _D1 to V _D2, the positive polarity alternating opposite substrate voltage V of om, voltage determined by three parties of the negative polarity scan signal (gate voltage) V _G0 to V _G2 is intended to be accumulated.

[0063] Then, including the point at which the voltage is accumulated and held up to the liquid crystal cell 4 ₁₁ to 4 ₂₂ again is selected, the remaining operations are the same as the operation of the fifth embodiment already described Therefore, further description will be omitted.

[0064] According to this embodiment, as in the fifth embodiment, throughout the operation period, substantially becomes possible to zero the average value of the voltage applied to each liquid crystal cell 4 ₁₁ to 4 _22, excellent The smear removing function can be exerted and a higher quality image can be displayed.

[0065]

As described above, according to the driving method of the present invention, the selection time (1H) for each one scanning line is set.
In inner, a drain voltage (display signal) applied to the signal line 2 as V _D, because of the use of the drain voltage (display signal) V _D consisting of a positive polarity and negative polarity, the selection time of one scanning line to be selected The fluctuation of the display effective voltage at the end of the selection time (1H) of each one scanning line can be extremely reduced without affecting the writing operation to the liquid crystal cell 4 at (1H). Therefore, the display state of the liquid crystal cell 4 is always kept constant,
There is an effect that smear generated on the display screen of the active matrix type liquid crystal display device can be greatly reduced and the display image quality can be improved.

Further, according to the driving method of the present invention, smear of the active matrix type liquid crystal display device can be greatly reduced even when the halftone display is performed.
There is an effect that an active matrix type liquid crystal display device having a good display image quality can be obtained.

[Brief description of drawings]

FIG. 1 is a partial configuration diagram showing a configuration of a first embodiment of a drive method according to the present invention and a drive signal waveform diagram thereof.

FIG. 2 is a partial configuration diagram showing a configuration of a second embodiment of a drive method according to the present invention and a drive signal waveform diagram thereof.

FIG. 3 is a partial configuration diagram showing a configuration of a third embodiment of a drive method according to the present invention and a drive signal waveform diagram thereof.

FIG. 4 is a partial configuration diagram showing a configuration of a fourth embodiment of a drive method according to the present invention and a drive signal waveform diagram thereof.

FIG. 5 is a block configuration diagram showing an example of the overall configuration of an active matrix type liquid crystal display device to which the driving method of the present invention is applied.

FIG. 6 is a partial configuration diagram showing a configuration of a fifth embodiment of a drive method according to the present invention and a drive signal waveform diagram thereof.

FIG. 7 is a partial configuration diagram showing a configuration of a sixth embodiment of a drive method according to the present invention and a drive signal waveform diagram thereof.

FIG. 8 is a partial configuration diagram showing a configuration of an example of a conventional driving method, and a drive signal waveform diagram thereof.

[Explanation of symbols]

1,1 _{0, 1} 1, 1 ₂ scan lines 2, 2 _1, 2 ₂ signal line 3,3 _11, 3 _12, 3 _21, 3 ₂₂ TFT (TF
_{T) 4,4 11, 4 12,} 4 21, 4 22 liquid crystal cell _{5,5 11, 5 12, 5 21} , 5 22 TFT drain-source stray capacitance 6,6 _11, 6 _12, 6 _21, 6 ₂₂ Inherent capacitance of liquid crystal cell 7, 7 ₁₁ , 7 ₁₂ , 7 ₂₁ , 7 ₂₂ Storage capacitance of ₂₂ liquid crystal cell 8 TFT-LCD (thin film transistor-liquid crystal cell) matrix substrate 9 Scanning side driving circuit 10 Signal side driving circuit 11 Counter substrate voltage Generation circuit 12 Display signal polarity reversal circuit 13 Controller 14 Image signal source

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masuyuki Ota 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd.

Claims (6)

[Claims] 1. A matrix substrate including a plurality of parallel-arranged scan lines, a plurality of parallel-arranged signal lines orthogonal to the scan lines, and thin-film transistors and liquid crystal cells arranged at respective intersections of the scan lines and the signal lines. And a driving method of an active matrix type liquid crystal display device having a scanning side driving circuit and a signal side driving circuit,
A driving method of an active matrix type liquid crystal display device, characterized in that a display signal having a positive polarity and a negative polarity is applied to each signal line within a selection time of each one scanning line. 2. The active matrix type liquid crystal display according to claim 1, wherein the display signal having the positive polarity and the negative polarity is formed by a display signal polarity inversion circuit connected to a signal side drive circuit. Device driving method. 3. The display signal having a positive polarity and a negative polarity has a positive polarity during a half of the selection time of each scan line and a negative polarity during the other half. Item 2. A method for driving an active matrix liquid crystal display device according to item 1. 4. The display signal having a positive polarity and a negative polarity is composed of two or more positive and negative portions within a selection time of each scan line. Driving method of active matrix type liquid crystal display device of. 5. The display signal having the positive polarity and the negative polarity has one polar part having a long duration and a low crest value and a short duration and a crest value within the selection time of each one scanning line. 2. The method for driving an active matrix type liquid crystal display device according to claim 1, wherein the product is composed of the other high polarity portion, and the products of the durations of the both polarity portions and the peak values are substantially equal. 6. The active matrix liquid crystal display device includes a counter substrate voltage generating circuit for generating an AC counter substrate voltage on a matrix substrate, and the polarity is inverted every one frame at every selection time of one scanning line. An alternating counter substrate voltage is applied to the matrix substrate.
6. A method for driving an active matrix liquid crystal display device according to any one of items 5 to 5.