JPH11109923A - Method of driving liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device and its driving method capable of high definition display that is about the same as a printing without increasing power consumption. SOLUTION: This liquid crystal display device is equipped with a pixel array part 1 in which scanning lines G and signal lines S are installed in matrix, with a scanning line driving circuit 2 for driving each scanning line G, with a signal line driving circuit 3 for driving each signal line S, and with a control circuit 4 for controlling the operation timing of the scanning line and the signal line driving circuits 2, 3. At the time of the ordinary display mode that is selected in displaying an animated picture, one pixel is displayed with a total of 16 pixel electrodes 6 consisting of four each in XY directions; at the time of high definition display mode that is selected in displaying a still picture, one pixel is displayed with one pixel electrode 6. At the time of high definition display mode, reduction in power consumption is contrived by making a display update cycle 16 times as long as one at the time of the ordinary display mode, instead of carrying out pixel display with an operating frequency 16 times that of the ordinary display mode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device which performs liquid crystal display by driving signal lines and scanning lines arranged in a matrix, and more particularly to a technique for performing high definition display.

[0002]

2. Description of the Related Art The panel size of a liquid crystal display device is mainly 12.1 inches in a large panel, and the maximum resolution at this size is the highest definition XGA (eXtended G).
raphics Array; 1024 x 768 pixels)
It is about pi (dot per inch). On the other hand, the resolution of printed matter is currently about 300 to 400 dpi, and the resolution is still insufficient to use a liquid crystal display instead of the printed matter.

[0003]

The reason that it is difficult to make the resolution of a liquid crystal panel comparable to that of a printed matter is that the number of pixels increases as the resolution increases, and the driving frequency increases as the number of pixels increases. This is because power consumption increases.

For example, in the case of the XGA standard panel, the power of the driving system for driving the panel is about 40% of the total power consumption, and the remaining 60% is consumed by the illumination system including the backlight. For this reason, the panel size is the same and the resolution is tripled to 30
At 0 dpi, the number of pixels increases nine times, and the power consumption of the drive system also increases nine times. At this time, the entire power consumption including the illumination system becomes about four times even if the increase in the luminance of the illumination system due to the decrease in the aperture ratio is not taken into account, and the battery life is reduced to about 1/4.

[0005] The present invention has been made in view of such a point, and an object of the present invention is to increase power consumption without increasing power consumption.
It is an object of the present invention to provide a driving method of a liquid crystal display device capable of performing a high-definition display comparable to a printed matter.

[0006]

In order to solve the above-mentioned problems, the present invention is directed to a plurality of signal lines and scanning lines arranged in a matrix and different combinations of these signal lines and scanning lines. A liquid crystal display device comprising: a pixel electrode provided on a pixel line; a signal line driving circuit for supplying a video signal to the signal line; and a scanning line driving circuit for supplying a scanning pulse at a frame cycle to any of the scanning lines. In the driving method, the scanning line driving circuit includes a first operation mode in which a scanning pulse is supplied at the same timing to adjacent predetermined scanning lines, and a scanning pulse is sequentially applied to the predetermined scanning line. And a second mode of operation to supply; and
The display update cycle in the first operation mode is shorter than the display update cycle in the second operation mode.

The first operation mode is selected, for example, when displaying a moving image, and the second operation mode is selected, for example, when displaying a still image.

According to a second aspect of the present invention, in the method for driving a liquid crystal display device according to the first aspect, the resolution in the second operation mode is m (m) of the resolution in the first operation mode.
Is an integer of 2 or more) times, and when the second operation mode is selected, the scanning line driving circuit sets the frame period of the second operation mode to the frame period of the first operation mode. After the display is performed for one frame, the display is not updated for the next (m-1) frame.

According to a third aspect of the present invention, in the driving method of the liquid crystal display device according to the first aspect, the resolution in the second operation mode is m (m) of the resolution in the first operation mode.
Is an integer of 2 or more), and the scanning line drive circuit sets one frame cycle in the second operation mode to m times one frame cycle in the first operation mode.

According to a fourth aspect of the present invention, in the method for driving a liquid crystal display device according to any one of the first to third aspects, the signal line driving circuit is provided corresponding to each of the signal lines, and a digital image is displayed. A plurality of first latch circuits each of which latches a signal once in one horizontal cycle, and a plurality of first latch circuits provided corresponding to each of the first latch circuits, for one horizontal cycle latched by the first latch circuit; And a plurality of second latch circuits for simultaneously latching the digital video signals, and each of the digital video signals latched by the second latch circuit is converted into an analog signal. And a D / A converter for performing a conversion. In the second operation mode, the latch timings of the plurality of first latch circuits are shifted by a predetermined time, and the first operation mode is shifted. Sometimes, the divided plurality of the first latch circuit into two or more sets, the same latch timing of the first latch circuit belonging to each set.

According to a fifth aspect of the present invention, in the method for driving a liquid crystal display device according to any one of the first to fourth aspects, a thin film transistor (Thin Fi) is provided corresponding to each of the pixel electrodes.
An active layer of these thin film transistors is formed of a polysilicon layer.

According to a sixth aspect of the present invention, in the method of driving a liquid crystal display device according to any one of the first to fifth aspects, the first line in which the signal line, the scanning line, and the pixel electrode are formed.
And a liquid crystal layer sandwiched between the first and second electrode substrates, and a liquid crystal layer sandwiched between the first and second electrode substrates. The layers are formed of ferroelectric or antiferroelectric liquid crystals.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display device to which the present invention is applied will be specifically described with reference to the drawings.
FIG. 1 is a block diagram of an embodiment of the liquid crystal display device according to the present invention. The liquid crystal display device of FIG. 1 includes a pixel array unit 1 in which scanning lines G and signal lines S are arranged in a matrix,
A scanning line driving circuit 2 for driving each scanning line G;
And a control circuit 4 for controlling the operation timing of the scanning line driving circuit 2 and the signal line driving circuit 3.

A thin film transistor (TFT) is located near each intersection of the scanning line G and the signal line S in the pixel array section 1.
A pixel electrode 6 is connected to each of the drain / source terminals of the TFT 5.
Opposing electrodes are arranged opposite to the pixel electrodes 6, and a liquid crystal is inserted between these electrodes. In addition, each TFT 5
In order to hold the voltage of the pixel electrode 6,
Is connected.

The liquid crystal display device of FIG. 1 has a normal display mode selected when displaying a moving image and a high definition display mode selected when displaying a still image. When the normal display mode is selected, one pixel is displayed by a total of 16 pixel electrodes 6 of four each in the X and Y directions, and when the high definition display mode is selected, one pixel electrode 6 displays one pixel. Display.

Although omitted in FIG. 1, the pixel array unit 1 has R (red), G (green), B (blue) for each pixel.
In the normal display mode, one pixel is displayed by four sets of these three signal lines S, that is, a total of 12 signal lines S. Hereinafter, in order to simplify the description, an example in which one signal line S is provided for each pixel will be described.

The signal line driving circuit 3 includes, for each signal line S,
A first latch circuit 11, a second latch circuit 12, and D
/ A converter 13 and a polarity inversion circuit 14.
The latch timing of the first and second latch circuits 11 and 12 and the polarity inversion timing of the polarity inversion circuit 14 are controlled by a signal from the timing signal supply circuit 15.

Each of the first latch circuits 11 latches the digital video data output from the control circuit 4 once in one horizontal cycle at a timing corresponding to the horizontal pixel position. Each of the second latch circuits 12 simultaneously latches all the latch data when the data of one horizontal line is latched by the first latch circuit 11. D
The / A converter 13 D / A converts the data latched by the second latch circuit 12 into an analog signal. The polarity inversion circuit 14 inverts the voltage level supplied to each signal line S for each frame (one screen) in order to prevent polarization of the liquid crystal.

FIG. 2 is a circuit diagram showing the internal configuration of the polarity inversion circuit 14. The polarity inversion circuit 14 includes two operational amplifiers 21 and 21 to which the output signal of the D / A converter 13 is input.
2 and two switch elements 23 and 24 connected to the output terminals of the operational amplifiers 21 and 22, respectively. The operational amplifier 21 outputs a signal of the same polarity as the output of the D / A converter 13, and the operational amplifier 22 outputs a signal of the opposite polarity to the output of the D / A converter 13. Switch elements 23, 24
Is turned on in response to a signal from the control circuit 4.

On the other hand, the scanning line drive circuit 2 shown in FIG. 1 has a timing signal supply circuit 16 and a buffer 17.
The pulse signal output from the timing signal supply circuit 16 is supplied to each scanning line G via the buffer 17.

When a still image is displayed, the user often looks at the screen while paying attention to a part of the image, and generally the viewing distance is short. Therefore, it is desirable to display the image at the highest possible resolution. On the other hand, when a moving image is displayed, the entire image is often viewed, and the viewing distance is generally long, so that the resolution required for displaying a still image is not necessary. In addition, a moving image has a much larger amount of information than a still image, and it is difficult to obtain a moving image having the same resolution as that of a printed matter in terms of a transmission band. Therefore,
In the present embodiment, when a still image is displayed, a high definition display mode is selected to perform high definition display, and when a moving image is displayed, a normal display mode is selected and display is performed at a normal resolution. I have to.

FIG. 3 is an operation timing chart of the signal line driving circuit 3 in the normal display mode, and FIG. 4 is a view showing an example of a liquid crystal screen display in the normal display mode. In the normal display mode, the first latch circuits 11 shown in FIG. 1 are grouped into groups of four, and the same video data is input to the first latch circuits 11 belonging to each group. As a result, the same video data is simultaneously supplied to four adjacent signal lines S. Figures 3 and 4
Indicates that video data “1” is connected to four signal lines S from the left end of the liquid crystal screen.
1A ”is supplied to the next four signal lines S to supply video data“ 12A ”.

On the other hand, the scanning line drive circuit 2 drives four adjacent scanning lines G at the same timing. FIG. 3 shows an example in which a pulse is simultaneously supplied to the four scanning lines G from the upper end of the liquid crystal screen, and then the pulses are simultaneously supplied to the four scanning lines G therebelow with a slight delay. As a result, FIG.
As shown in (1), the same data is displayed on adjacent 4 × 4 pixels in the panel.

In the present embodiment, when a high-definition display is required for a document or a drawing containing fine characters, the normal display mode is switched to the high-definition display mode. The mode switching is performed, for example, by inputting a mode switching signal to the control circuit 4 from outside. More specifically, the normal display mode and the high definition display mode are selected based on the amount of image data stored in the frame memory. Alternatively, the mode may be manually switched.

FIG. 5 is an operation timing chart of the signal line driving circuit 3 in the high definition display mode, and FIG. 6 is a diagram showing an example of a liquid crystal screen display in the high definition display mode.

In the high-definition display mode, when each of the driving circuits 2 and 3 is operated at the same driving frequency as in the normal display mode, one frame period becomes 16 times as large as that in the normal display mode.
This is because the number of pixels is increased 16 times in the normal display mode. On the other hand, in order to make the length of one frame period the same as in the normal display mode, it is necessary to increase the drive frequency by 16 times. However, the driving frequency and the power consumption are almost proportional to each other. When the driving frequency is increased by 16 times, the power consumption is also increased by 16 times.

For this reason, in this embodiment, power consumption is reduced by making the display update cycle in the high definition display mode slower than the display update cycle in the normal display mode.
Hereinafter, a method of setting the display update cycle according to the present embodiment will be described in detail.

In a CRT (Cathode Ray Tube) that performs display by scanning a cathode ray tube with an electron gun, an image cannot be displayed unless scanning is continued at a constant period. Once a pixel voltage is applied to the pixel electrode 6 shown in (1), the voltage is maintained for a while after that, and display according to the voltage is continued. By utilizing such a property, in the present embodiment, in the high-definition display mode, the length of one frame period is set to 1/60 (sec) which is the same as the conventional one.
After displaying one frame, the display is not updated in the subsequent 15 frames. That is, in the present embodiment, the power consumption is reduced by setting the display update cycle to 16/60 (sec), which is 16 times longer than the conventional display cycle.

By the way, in a display device such as a personal computer, a moving image such as a mouse cursor may be displayed in a part of a still image while the still image is being displayed. In this case, it is desirable to display in the high-definition display mode if the motion of the moving image is slow, and to display in the normal display mode if it is necessary to display the moving image smoothly (in real time). For example, in the case where the mouse cursor is displayed, the time required for the mouse cursor to move is slightly shorter than the usage time of a personal computer or the like. It is desirable to smooth the movement of the mouse cursor.

When displaying an image in which a still image and a moving image are mixed, it is desirable to perform the display in the normal display mode. In this case, the resolution of the still image in the liquid crystal screen is reduced, but the motion of the moving image can be smoothed, and the moving image and the still image can be displayed simultaneously without increasing power consumption.

In the above-described embodiment, an example has been described in which the driving frequency in the high definition display mode is set to 16 times the frequency in the normal display mode. However, it is difficult to increase the driving frequency of the liquid crystal screen. In such a case, the driving frequency may be reduced. If the driving frequency is reduced, it takes time to display one frame, but there is not much effect when displaying a still image. If the drive frequency is reduced, the frame cycle becomes longer. As a result, the display update cycle becomes longer, and the power consumption can be reduced.

By the way, a conventional liquid crystal display device has a TFT
The glass substrate on which the pixel electrodes 5 and the pixel electrodes 6 are formed, and a driving circuit composed of an LSI or the like are connected by TAB (Tape Automated Bonding).
connection), the connection pitch by the TAB method is limited to about 60 μm. To obtain a resolution of 300 dpi or more, the connection pitch must be 28 μm in the case of an RGB stripe arrangement.
μm or less, and the TAB method cannot be used for a high-resolution panel as in the present embodiment.

For this reason, in the present embodiment, a drive circuit is integrally formed on a glass substrate on which the TFTs 5 and the pixel electrodes 6 are formed, and connection between the signal lines S and the like and the drive circuit is performed on the glass substrate. I have. Conventionally, an amorphous silicon type TFT (a-Si type TFT) is used as a switch element in a drive circuit.
Although FT) was often used, the a-Si type TFT has a mobility of only 1 [cm ² / Vs] or less, and the driving frequency cannot be improved much. Therefore, in the present embodiment, the mobility is a-Si
Polysilicon type TFT (p
-Si-type TFT).

In this embodiment, when the high definition display mode is selected, the display update cycle of the screen is lengthened to reduce the power consumption. However, as the display update cycle becomes longer, flicker occurs. It will be easier. Flicker occurs when the light intensity of each pixel changes between frames, and when flicker occurs, the display quality deteriorates. The main causes of the change in light intensity are pixel voltage fluctuation due to switching noise of the switching element and pixel voltage fluctuation due to leak current.

In order to suppress both the switching noise and the pixel voltage fluctuation due to the leak current, it is effective to increase the pixel capacitance value including the auxiliary capacitance 7. Auxiliary capacity 7
In order to increase the capacitance value, a method of increasing the area of the auxiliary capacitor 7, a method of reducing the dielectric thickness, a method of using a high dielectric constant dielectric material such as Ta ₂ O ₅ , a method of forming a trench type capacitor, and the like are described. Conceivable. To increase the area of the auxiliary capacitance 7,
It is desirable to form a transparent capacitor using indium tin oxide (ITO) or the like. Further, the pixel capacitance value can be increased by increasing the capacitance (liquid crystal capacitance) of the pixel electrode 6 itself. A normal TN (Twisted Nematic) liquid crystal has a relative dielectric constant of about 10, but a ferroelectric or anti-dielectric liquid crystal material has a relative dielectric constant of 100 to 1000, and can increase the pixel capacitance value.

In addition, in order to suppress the pixel voltage fluctuation due to the switching noise, a method of reducing the capacitance between the terminals of the switch element and the size of the switch element can be considered. To suppress this, it is effective to reduce the leak current itself of the switch element.

FIG. 7 is a plan view of the pixel array section 1 shown in FIG. 1, and FIG. 8 is a sectional view taken along line AA 'of FIG. As shown in these figures, a plurality of signal lines S and scanning lines G are formed in a matrix on the first electrode substrate 51, and p is located near each intersection of the signal lines S and scanning lines G. -The switch element 5 made of a Si type TFT is formed. The gate terminals of these switch elements 5 are connected to the scanning lines G, and the drain / source terminals are connected to the signal lines S.

The video data is supplied to the drain / source terminal of the p-Si TFT 5 via the signal line S and the contact hole 52. When the p-Si TFT 4 is turned on, the video data is transparent via the contact hole 52. It is supplied to the pixel electrode 6 formed of a conductive film. A counter electrode 54 is formed on the second electrode substrate 53, the pixel electrode 6 and the counter electrode 54 are arranged to face each other, and a liquid crystal 55 is inserted between them.

A part 56 of the scanning line G is formed wide as shown in FIG.
The storage capacitor 7 is formed via the interlayer insulating film. Part of the pixel electrode 6 overlaps with the signal line S and the scanning line G, and light transmitted through portions other than the pixel electrode 6 is blocked by the signal line S and the scanning line G. In order to perform color display, R (red), G (green),
Color filters 57r, 57g, and 57b for B (blue) are formed.

As the switch element 5 in the pixel array section 1, as in the case of the switch element in the drive circuit, p-Si
It is desirable to use a type TFT. Since the a-Si type TFT has a large charging time constant for the pixel capacitance, there is a possibility that the charging to the pixel capacitance may not be in time when the driving frequency is increased. Since the constant is smaller by about two digits, there is no possibility that the charging of the pixel capacitance cannot be completed in time.

In this embodiment, as an example, an a-Si film is deposited by a plasma CVD method using silane gas, and this a-Si film is deposited.
The active layer of the p-Si type TFT 5 was formed by a process of irradiating the film with an excimer laser to melt and recrystallize. The thickness of the active layer was set to about 500 angstroms. The polysilicon film of the p-Si type TFT 5 may be formed by a method of directly forming a polysilicon film using a low-pressure CVD method, or a method of forming an a-Si film in a heat treatment furnace at about 600 ° C. It can also be formed by a method such as solid phase growth.

In the present embodiment, the gate insulating film of the p-Si type TFT 5 is formed from a silicon oxide film formed by the plasma CVD method. The gate electrode is formed using a low-resistance molybdenum-tungsten alloy so that the image quality does not deteriorate due to the signal delay of the scanning line G even in a large liquid crystal panel, and the molybdenum-tungsten alloy is formed by a sputtering method. did.

Further, the source / drain regions of the p-Si type TFT 5 were formed by implanting phosphorus by ion doping using the gate electrode as a mask. A silicon oxide film formed by a plasma CVD method was used as the interlayer insulating film. After forming a contact hole by a dry etching method, source / drain electrodes made of a Mo / Al / Mo film were formed by a sputtering method. Here, the molybdenum film is used to form an ohmic junction with the pixel electrode 6 formed using the ITO film.

Since the mobility of the p-Si type TFT 5 is about two orders of magnitude higher than that of the a-Si thin film transistor, the peripheral driving circuit can be formed on the glass substrate at the same time. For peripheral circuits, use CM to achieve higher speed and lower power consumption.
It is desirable to use OS configuration. For this reason, in the present embodiment, the impurity doping step is performed in two steps of the P-type and N-type impurity doping steps using the register mask.

The switching element 5 made of a p-Si type TFT is a low-leakage TFT so that the pixel potential can be maintained even when the frame period is 16 times the normal value. In order to make such a low-leakage TFT, dangling bonds in the polysilicon film are terminated by using hydrogen plasma treatment to lower the level density in the band, and LDD (Lightly Doped Drain) is performed by a sidewall process or a resist mask. The structure is formed to prevent a tunnel current due to a drain electric field, the thickness of the active layer is set to 500 Å or less to completely deplete the channel at the time of cutoff, and the channel width of the TFT 5 is set to a minimum value determined by the design rule (1 μm
Using rules).

As described above, in the present embodiment, since the channel width is reduced to the minimum value, the pixel voltage fluctuation at the time of switching depending on the gate capacitance can be reduced to such an extent that it is not detected as flicker.

As described above, in this embodiment, a low-leakage TFT is used so that flicker does not occur even if the frame period is lengthened. However, flicker can be prevented by increasing the pixel capacitance. This is because the pixel voltage fluctuation that causes flicker decreases in inverse proportion to the pixel capacitance. As a method of increasing the pixel capacitance, a method of increasing the capacitance (liquid crystal capacitance) of the pixel electrode 6 itself or a method of increasing the auxiliary capacitance 7
There is a way to increase the size.

As a method of increasing the liquid crystal capacitance, there are a method of reducing the cell gap, a method of using a liquid crystal material having a high dielectric constant, and the like. As for the latter, it is more effective to use a ferroelectric material such as a ferroelectric liquid crystal and an antiferroelectric liquid crystal. The relative permittivity of the ferroelectric liquid crystal material is 100 to 1000,
Relative permittivity of nematic liquid crystal used in the above embodiment
(About 10), the flicker amount under the same driving condition can be reduced by one or two digits. In particular, when an antiferroelectric liquid crystal material having no hysteresis is used, a liquid crystal display device having the same pixel configuration and circuit configuration as the above embodiment can be configured.

As a method of increasing the capacitance value of the auxiliary capacitor 7, a method of increasing the area of the auxiliary capacitor 7, a method of reducing the dielectric film thickness of the auxiliary capacitor 7, and a method of increasing the relative dielectric constant of the dielectric film are used. There is a method using a material. As a method of increasing the area of the storage capacitor 7, a method of using a transparent storage capacitor using a transparent conductive film such as ITO as an electrode material and a transparent dielectric material such as SiO ₂ as a dielectric material can prevent a decrease in aperture ratio. Is effective. Methods for increasing the relative dielectric constant include barium titanate (BaTiO ₃ ) and strontium titanate (S
It is effective to use a perovskite crystal-based high and ferroelectric material such as rTiO ₃ ).

In the above-described embodiment, an example of a so-called transmission type liquid crystal display device in which illumination light is applied from the first electrode substrate side and viewed from the second electrode substrate side has been described.
The present invention can be configured irrespective of the presence or absence of illumination light, and power is not consumed when there is no illumination light, so that power consumption can be reduced efficiently.

In the above-described embodiment, the active matrix type liquid crystal display device having the switch element 5 for each pixel has been described. However, the present invention can be applied to an STN type liquid crystal display device.

[0052]

As described above in detail, according to the present invention, as the scanning line driving mode, the first operation mode capable of displaying a moving image and the second operation mode capable of displaying a high resolution image are provided. Is provided, and the display update period in the first operation mode is shorter than the display update period in the second operation mode. Therefore, even if high-definition display comparable to that of printed matter is performed, power consumption does not increase.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a circuit diagram showing an internal configuration of a polarity inversion circuit.

FIG. 3 is an operation timing chart of a signal line driving circuit in a normal display mode.

FIG. 4 is a diagram showing a liquid crystal screen display example in a normal display mode.

FIG. 5 is an operation timing chart of a signal line driver circuit in a high definition display mode.

FIG. 6 is a diagram showing a display example of a liquid crystal screen in a high definition display mode.

FIG. 7 is a plan view of the pixel array unit shown in FIG. 1;

FIG. 8 is a sectional view taken along line AA ′ of FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pixel array part 2 Scan line drive circuit 3 Signal line drive circuit 4 Control circuit 5 p-type TFT 6 Pixel electrode 7 Auxiliary capacity 11 1st latch circuit 12 2nd latch circuit 13 D / A converter 14 Polarity inversion circuit 15 , 16 timing signal supply circuit 17 buffer

Claims (6)

[Claims] 1. A plurality of signal lines and scanning lines arranged in a matrix, pixel electrodes provided for different combinations of these signal lines and scanning lines, and a signal line drive for supplying a video signal to the signal lines Circuit, and a scanning line driving circuit that supplies a scanning pulse to the arbitrary scanning line at a frame cycle. A driving method of a liquid crystal display device, comprising: On the other hand, it has a first operation mode for supplying a scan pulse at the same timing, and a second operation mode for supplying a scan pulse line-sequentially to the scan line of the predetermined row, and in the first operation mode. A method for driving a liquid crystal display device, wherein a display update cycle is shorter than a display update cycle in the second operation mode. 2. The resolution in the second operation mode is m (m is an integer of 2 or more) of the resolution in the first operation mode.
When the second operation mode is selected, the scanning line drive circuit sets the frame period of the second operation mode to be the same as the frame period of the first operation mode, and The method according to claim 1, wherein after the display for the frame is performed, the display is not updated for the next (m−1) frames. 3. The resolution in the second operation mode is m (m is an integer of 2 or more) of the resolution in the first operation mode.
The scanning line drive circuit sets one frame period in the second operation mode to m times the one frame period in the first operation mode. 3. The method for driving a liquid crystal display device according to item 1. 4. A plurality of first latch circuits provided corresponding to each of the signal lines, respectively, for latching a digital video signal once in one horizontal cycle, and a plurality of first latch circuits, respectively. A plurality of second latch circuits provided corresponding to the respective latch circuits, and for simultaneously latching the digital video signal for one horizontal cycle latched by the first latch circuit; And a D / A converter provided for each of the digital video signals latched by the second latch circuit to convert the digital video signal into an analog signal. In the first operation mode, the plurality of first latch circuits are divided into two or more sets, and the first latches belonging to each set are shifted in the first operation mode. Method for driving a liquid crystal display device according to claim 1, characterized in that the same latch timing of latch circuit. 5. A thin film transistor is provided corresponding to each of said pixel electrodes, and an active layer of said thin film transistor is formed of a polysilicon layer. Or a driving method of the liquid crystal display device. 6. A first electrode substrate on which the signal line, the scanning line, and the pixel electrode are formed, a second electrode substrate on which a counter electrode arranged to face the pixel electrode is formed,
6. A liquid crystal layer sandwiched between the first and second electrode substrates, wherein the liquid crystal layer is formed of a ferroelectric or antiferroelectric liquid crystal. A driving method of the liquid crystal display device according to any one of the above.