JPH03174116A - Driving method for liquid crystal electrooptical device - Google Patents

Abstract

PURPOSE:To obtain a high contrast and to lessen the burden of viewer's eyes by driving a liquid crystal electrooptical device of >=200 duty number with 200 to 280Hz frame frequencies. CONSTITUTION:The liquid crystal electrooptical device which is constituted by crimping a nematic liquid crystal having a positive dielectric anisotropy and added with an optically active substance between a pair of upper and lower electrode substrates disposed to face each other, is formed with the spiral structure twisted in a range from 180 to 270 deg. in the thickness direction thereof and has >=200 duty number is driven by the frame frequencies of 200 to 280Hz at the time of time divided driving of this device. A level down arises first in a non-selection period 3 when a pulse 1 is impressed to the liquid crystal and the display turns black in a selection period 2. Since the frame frequencies are increased in this case, the size 4 of the level down decreases and the sharp black display is executed. The contrast of the display screen is drastically increased in this way.

Description

[Detailed Description of the Invention] [Prior Art] A nematic liquid crystal having positive dielectric anisotropy and added with an optically active substance has been sandwiched between a pair of upper and lower electrode substrates disposed opposite to each other. A TN type liquid crystal electro-optical device having a panel having a helical structure twisted at 90 degrees in the thickness direction has been used in watches, calculators, and the like.

However, this TN-type liquid crystal electro-optical device does not have a clear threshold of applied voltage for liquid crystal switching, and when used in relatively large displays, etc., the contrast becomes very small, and it is practically impossible to use large displays. It was impossible to use it for

However, liquid crystal electro-optical devices called STN type have become quite popular as displays for relatively large word processors and the like. This STN (SuperTwisted
Nematic ) type liquid crystal electro-optical device structure TN
The difference from the type liquid crystal electro-optical device is that the twist angle of the liquid crystal is not 90 degrees but 180 degrees to 270 degrees. As a result, the voltage threshold for switching the liquid crystal is clearer than that of the STNTN type liquid crystal electro-optical device and the TN type liquid crystal electro-optical device. It has now become possible to apply it to large displays.

Conventionally, STN-type liquid crystal electro-optical devices have been designed for large screens that cannot be displayed with TN-type liquid crystal electro-optical devices, especially those with a duty cycle of 200.
It is often used in displays of 240 to 240.

The frame frequency when displaying this STN type liquid crystal electro-optical device was exclusively 120 to 160)1z.

[Problems with conventional technology]

As mentioned above, ST with a duty number of 200 to 240
FIG. 2(a) shows the state when an N-type liquid crystal electro-optical device is driven in a time-division manner from 120 to 160)1z.

Shown in (b). Figure 2 (a) shows the voltage waveform applied to a certain pixel on the display, and Figure 2 (b) shows the waveform of the voltage applied to a certain pixel on the display, and Figure 2 (b) shows the voltage waveform when the amount of transmitted light at that pixel is converted into voltage by a photomultiplier and input to the oscilloscope. Shows the white waveform.

When an STN type liquid crystal display is time-divisionally driven and a voltage pulse as shown in FIG. 2(a) is applied to the pixels (all ON waveforms), the liquid crystal responds at the time of selection and the display approaches black. However, when it is not selected, the level gradually decreases and the display becomes one color closer to white. In fact, for the viewer, the display is perceived as white or black based on the amount of transmitted light when the amount of transmitted light is integrated over a certain period of time, so if this level drop is large, the display will be black. However, as the amount of transmitted light increases, the display becomes close to white.

This increases the eye strain of the viewer and causes a decrease in visual acuity. Even if you actually measure the contrast of the display screen, the amount of transmitted light increases when displaying black.
It is also clear that the contrast is reduced.

[Structure of the invention]

In order to solve the above-mentioned problems, the present invention provides a method in which a nematic liquid crystal having positive dielectric anisotropy and added with an optically active substance is sandwiched between a pair of upper and lower electrode substrates disposed opposite to each other, and the nematic liquid crystal is It forms a twisted spiral structure in the range of 180 degrees to 270 degrees, and is characterized by being driven at a frame frequency of 200 to 280 Hz when time-divisionally driving a liquid crystal electro-optical device with a duty number of 200 sides. do.

In the present invention, the frame frequency is the reciprocal of the time from when an arbitrary scanning line is selected until the next selection.

The present invention will be explained using FIGS. 1(a) and 1(b).

Figure 1 (a) shows the voltage waveform applied to a certain pixel on the display layer, and Figure 1 (b) shows the amount of transmitted light at that pixel converted into voltage by a photomultiplier and input to the oscilloscope. Shows the white waveform.

First, in the selection period (2), pulse (1) is applied to the liquid crystal and the display becomes black, and then in the non-selection period I'1lli (3
), but in the present invention, the frame frequency is made larger than before, so the magnitude of the level-down (4) is smaller than before. Therefore, if the amount of transmitted light is integrated within a certain period of time, the integrated value will be smaller than in the conventional case, and a clearer black display can be achieved.

Therefore, the contrast of the display screen is also significantly increased compared to the conventional technology.

The present invention will be explained below using Examples.

[Example 1] First, IT was placed on the first soda glass substrate as a transparent electrode.
After forming an O thin film using a DC sputtering method, 640 control electrodes are manufactured using a known photolithography method.

In addition, IT was placed on the second soda glass substrate in a similar manner.
240 scanning electrodes made of O are prepared.

Then, polyamic acid is applied onto the first and second substrates using an offset printing machine, and heated at 300° C. for 3 hours to obtain a polyimide thin film.

Then, the polyimide thin films on both substrates are rubbed using cotton cloth. However, the rubbing directions of the first substrate and the second substrate are made to intersect at an angle of 240 degrees.

Then, spherical fine particles (spacers) consisting of 5 in 2 particles with a diameter of 7.5 μm are sprinkled on one substrate, and an epoxy sealing material is screen printed on the other substrate, and the substrates are bonded together.

Thereafter, liquid crystal is injected using a known vacuum injection method to produce a liquid crystal driving panel. However, the center of the panel was swollen as it was, so a re-pressing process was performed here. In other words, pressure was applied toward the inside of the cell in order to force the excess liquid crystal injected out of the cell. The liquid crystal injection port was then sealed with ultraviolet curing resin to complete the liquid crystal panel.

Then, a pair of polarizing plates are placed on both sides of the liquid crystal panel.

Thereafter, the liquid crystal panel and the drive circuit were connected using FPC.

The thus completed liquid crystal electro-optical device has a duty cycle of 24.
0. Driven at a frame frequency of 280 Hz. The liquid crystal panel was then irradiated with white light, and the light that passed through the liquid crystal panel was converted into voltage using a photomultiplier, which was input into an oscilloscope to measure the contrast. Result 3
A high contrast of 5 was obtained. Further, Table 1 shows the results of contrast measurements performed while keeping the duty number constant and changing the frame frequency (240).

Table 1 As can be seen from Table 1, on the frequency 200Hz side, 2
A high contrast on the 0 side was obtained.

In comparison, only low contrast was obtained at 120 to 180 Hz.

[Example 2] First, IT was placed on the first soda glass substrate as a transparent electrode.
After forming an O thin film using a DC sputtering method, 640 control electrodes are manufactured using a known photolithography method.

In addition, IT was placed on the second soda glass substrate in a similar manner.
240 scanning electrodes made of O are prepared.

Then, polyamic acid is applied onto the first and second substrates using an offset printing machine, and heated at 300° C. for 3 hours to obtain a polyimide thin film.

Then, the polyimide thin films on both substrates are rubbed using cotton cloth. However, the rubbing directions of the first substrate and the second substrate are made to intersect at an angle of 240 degrees.

Then, spherical fine particles (spacers) made of SiO□ with a diameter of 7.5 μm are scattered on one substrate, and an epoxy sealing material is screen printed on the other substrate, and the substrates are bonded together.

Thereafter, liquid crystal is injected using a known vacuum injection method to produce a liquid crystal driving panel. However, the center of the panel was swollen as it was, so a re-pressing process was performed here. In other words, pressure was applied toward the inside of the cell in order to force the excess liquid crystal injected out of the cell. The liquid crystal injection port was then sealed with ultraviolet curing resin to complete the liquid crystal panel.

Then, a pair of polarizing plates are placed on both sides of the liquid crystal panel.

Thereafter, the liquid crystal panel and the drive circuit were connected using FPC.

The thus completed liquid crystal electro-optical device has a duty cycle of 24.
Contrast measurements were performed at frame frequencies of 0 and 60, and at frame frequencies of 280 Hz and 140 Hz, respectively. The results are shown in Table 2. In the table, l/60 means the duty number 60, and 1/240 means the duty number 240.
shows.

Table 2 As is clear from Table 2, driving at a frame frequency of 200 Hz to 280 Hz as described in the present invention is particularly effective when the duty number becomes large, and when the duty number is as small as about 60, the frequency It can be seen that high contrast can be obtained without dependence.

[Example 3] First, IT was placed on the first soda glass substrate as a transparent electrode.
After forming an O thin film using a DC sputtering method, 640 control electrodes are manufactured using a known photolithography method.

In addition, IT was placed on the second soda glass substrate in a similar manner.
240 scanning electrodes made of O are prepared.

Then, polyamic acid is applied onto the eleventh and second substrates using an offset printing machine, and heated at 300° C. for 3 hours to obtain a polyimide thin film.

Then, the polyimide thin films on both substrates are rubbed using cotton cloth. However, the rubbing directions of the first substrate and the second substrate are made to intersect at an angle of 240 degrees.

Then, spherical fine particles (spacers) made of SiO2 with a diameter of 5.5 μm are scattered on one substrate, and an epoxy sealing material is screen printed on the other substrate, and the substrates are bonded together.

Thereafter, liquid crystal is injected using a known vacuum injection method to produce a liquid crystal driving panel. However, the center of the panel was swollen as it was, so a re-pressing process was performed at this point. In other words, pressure was applied toward the inside of the cell in order to force the excess liquid crystal injected out of the cell. The liquid crystal injection port was then sealed with ultraviolet curing resin to complete the liquid crystal panel.

By attaching one retardation film with Δnd of 305 nm and one retardation film with Δnd of 390 nm to either side of the liquid crystal panel, and placing a pair of polarizing plates on both sides of the liquid crystal panel, the STN-specific A black and white liquid crystal panel was produced by erasing the coloring.

Thereafter, the liquid crystal panel and the drive circuit were connected using FPC.

The thus completed liquid crystal electro-optical device has a duty cycle of 24.
0. Driven at a frame frequency of 280 Hz. The liquid crystal panel was then irradiated with white light, and the light that passed through the liquid crystal panel was converted into voltage using a photomultiplier, which was input into an oscilloscope to measure the contrast. Result 6
A high contrast of 4 was obtained. Further, Table 3 shows the results of contrast measurements performed while keeping the duty number constant and changing the frame frequency (240).

Table 3 As can be seen from Table 3 above, a high contrast of 50 sides was obtained on the 200 Hz frequency side.

In comparison, only low contrast was obtained at 120-180H2.

[Example 4] First, IT was placed on the first soda glass substrate as a transparent electrode.
After forming a thin film using a DC sputtering method, 640 control electrodes are manufactured using a known photolithography method.

In addition, ITO was deposited on the second soda glass substrate in the same manner.
240 scanning electrodes consisting of

Then, polyamic acid is applied onto the first and second substrates using an offset printing machine, and heated at 300° C. for 3 hours to obtain a polyimide thin film.

Then, the polyimide thin films on both substrates are rubbed using cotton cloth. However, the rubbing directions of the first substrate and the second substrate are made to intersect at an angle of 240 degrees. Then, spherical fine particles (spacers) made of Sin having a diameter of 5.5 μm are scattered on one substrate, and an epoxy sealing material is screen printed on the other substrate, and the substrates are bonded together.

Thereafter, liquid crystal is injected using a known vacuum injection method to produce a liquid crystal driving panel. However, the center of the panel was swollen as it was, so a re-pressing process was performed here. In other words, pressure was applied toward the inside of the cell in order to force the excess liquid crystal injected out of the cell. The liquid crystal injection port was then sealed with ultraviolet curing resin to complete the liquid crystal panel.

By attaching one retardation film with Δnd of 305 nm and one retardation film with Δnd of 390 nm to either side of the liquid crystal panel, and placing a pair of polarizing plates on both sides of the liquid crystal panel, the STN-specific A black and white liquid crystal panel was produced by erasing the coloring.

Thereafter, the liquid crystal panel and the drive circuit were connected using FPC.

The thus completed liquid crystal electro-optical device has a duty cycle of 24.
Contrast measurements were performed at frame frequencies of 0 and 60, and at frame frequencies of 280 Hz and 140 Hz, respectively. The results are shown in Table 4. In the table, 1/60 means 60 duties, and 1/240 means 240 duties.
shows.

Table 4 As is clear from Table 4, driving at a frame frequency of 200 Hz to 280 Hz as described in the present invention is particularly effective when the duty number becomes large, and when the duty number is as small as about 60, the frequency It can be seen that high contrast can be obtained without dependence.

[Example 5] First, IT was placed on the first soda glass substrate as a transparent electrode.
After forming a thin film using a DC sputtering method, 640 control electrodes are manufactured using a known photolithography method.

In addition, IT was placed on the second soda glass substrate in a similar manner.
240 scanning electrodes made of O are prepared.

Then, polyamic acid is applied onto the first and second substrates using an offset printing machine, and heated at 300''C for 3 hours to obtain a polyimide thin film.

Then, the polyimide thin films on both substrates are rubbed using cotton cloth. However, the rubbing directions of the first substrate and the second substrate are made to intersect at an angle of 240 degrees.

Then, spherical fine particles (spacers) made of 5i02 with a diameter of 5.5 μm are scattered on one substrate, and an epoxy sealing material is screen printed on the other substrate, and the substrates are bonded together.

Thereafter, liquid crystal is injected using a known vacuum injection method to produce a liquid crystal driving panel. However, the center of the panel was swollen as it was, so a re-pressing process was performed here. In other words, pressure was applied toward the inside of the cell in order to force the excess liquid crystal injected out of the cell. The liquid crystal injection port was then sealed with ultraviolet curing resin to complete the liquid crystal panel.

Then, one retardation film with Δnd of 350 nm was pasted on each side of the liquid crystal panel, and a pair of polarizing plates were placed on both sides of the liquid crystal panel to eliminate the coloring peculiar to STN and produce a monochrome liquid crystal panel.

Thereafter, the liquid crystal panel and the drive circuit were connected using FPC.

The thus completed liquid crystal electro-optical device has a duty cycle of 24.
0. Driven at a frame frequency of 280 Hz. The liquid crystal panel was then irradiated with white light, and the light that passed through the liquid crystal panel was converted into voltage using a photomultiplier, which was input into an oscilloscope to measure the contrast. Result 6
A high contrast of 2 was obtained. Further, Table 5 shows the results of contrast measurements performed while keeping the duty number constant (240) and varying the frame frequency.

Table 5 As can be seen from Table 5, a high contrast of 50 sides was returned on the frequency side of 200 Hz.

In comparison, only low contrast was obtained at frame frequencies of 120 to 180 Hz.

[Example 6] First, IT was placed on the first soda glass substrate as a transparent electrode.
After forming an O thin film using a DC sputtering method, 640 control electrodes are manufactured using a known photolithography method.

In addition, IT was placed on the second soda glass substrate in a similar manner.
240 scanning electrodes made of O are prepared.

Then, polyamic acid is applied onto the eleventh and second substrate using an offset printing machine, and heated at 300'C for 3 hours to obtain a polyimide thin film.

Then, the polyimide thin films on both substrates are rubbed using cotton cloth. However, the rubbing directions of the first substrate and the second substrate are made to intersect at an angle of 240 degrees.

Then, spherical fine particles (spacers) made of SiO□ with a diameter of 5.5 μm are sprinkled on one substrate, and an epoxy sealing material is screen printed on the other substrate, and the substrates are bonded together.

Thereafter, liquid crystal is injected using a known vacuum injection method to produce a liquid crystal driving panel. However, the center part of the panel was swollen as it was, so I went through the pressing process again. In other words, pressure was applied toward the inside of the cell in order to force the excess liquid crystal injected out of the cell. The liquid crystal injection port was then sealed with ultraviolet curing resin to complete the liquid crystal panel.

Then, one retardation film with a Δnd of 350 nm was pasted on each side of the liquid crystal panel, and a pair of polarizing plates were placed on both sides of the liquid crystal panel to eliminate the coloring peculiar to STN and produce a monochrome liquid crystal panel.

Thereafter, the liquid crystal panel and the drive circuit were connected using FPC.

The thus completed liquid crystal electro-optical device has a duty cycle of 24.
Contrast measurements were carried out in the case of 0 and 60, respectively, in the case of frame frequency 280H2 and in the case of 140)1z. The results are shown in Table 6. In addition, 1/60 in the table
is the duty number 60, 1/240 is the duty number 24
Indicates 0.

Table 6 As is clear from Table 6, driving at a frame frequency of 200 Hz to 280 Hz as described in the present invention is particularly effective when the duty number becomes large, and when the duty number is as small as about 60, the frequency It can be seen that high contrast is obtained without dependence.

[Example 7] After forming an ITO thin film as a transparent electrode on a first soda glass substrate using a DC sputtering method, a control electrode is produced using a known photolithography method.

Scanning electrodes made of ITO are fabricated on a second soda glass substrate in a similar manner.

Then, polyamic acid is sprayed onto the first and second substrates using an offset printing machine, and heated at 300° C. for 3 hours to obtain a polyimide thin film.

Then, the polyimide thin films on both substrates are rubbed using cotton cloth. However, the first substrate and the second
The rubbing directions of the substrates are made to intersect at an angle of 240 degrees.

Then, spherical fine particles (spacers) made of SiL with a diameter of 6.2 μm are scattered on one substrate, and an epoxy sealant is screen printed on the other substrate, and the substrates are bonded together.

Thereafter, liquid crystal is injected using a known vacuum injection method to produce a liquid crystal driving panel. However, the center of the panel was swollen as it was, so a re-pressing process was performed here. In other words, pressure was applied toward the inside of the cell in order to force the excess liquid crystal injected out of the cell. Then, the liquid crystal injection port was sealed using an ultraviolet curing resin to complete a liquid crystal driving panel.

Next, an optical compensation panel is produced.

Third. After spraying polyamic acid on the fourth soda glass substrate using an offset printing machine, heating is performed at 300 degrees for 3 hours to obtain a polyimide thin film.

Then, the polyimide thin films on both substrates are rubbed using cotton cloth. However, the rubbing directions of the third substrate and the fourth substrate are made to intersect at an angle of 240 degrees in the opposite direction to that of the liquid crystal driving panel. Also, the third
The rubbing direction of the second substrate was made to intersect with the rubbing direction of the second substrate of the liquid crystal driving panel at an angle of 80 degrees.

Then, spherical fine particles (spacers) made of SiO□ with a diameter of 7.5 μm are scattered on one substrate, and an epoxy sealing material is screen printed on the other substrate, and the substrates are bonded together.

Thereafter, liquid crystal is injected using a known vacuum injection method to produce an optical compensation panel.

However, as it was, the center of the panel was swollen, so a re-pressing process was performed here. In other words, pressure was applied toward the inside of the cell in order to force the excess liquid crystal injected out of the cell.

Then, the liquid crystal injection port was sealed using an ultraviolet curing resin to complete an optical compensation panel.

And polarizing plates (16), (17), light source (20),
A liquid crystal driving panel (11) was arranged as shown in FIG.

Figure 3 shows the configuration of the liquid crystal panel in this example.
0) side, the absorption axis direction of the first polarizing plate (16), the liquid crystal orientation direction of the light source side substrate (14) in the liquid crystal driving panel (11), and the substrate (1) on the optical compensation panel (12) side.
4) Liquid crystal alignment direction and optical compensation panel (12)
The substrate (15) on the side of the liquid crystal drive panel (11) in
liquid crystal alignment direction, the substrate (1) on the second polarizing plate (17) side
5.) is a schematic representation of the liquid crystal alignment direction and the absorption axis direction of the second polarizing plate (17).

As is clear from FIG. 3, the liquid crystal alignment direction of the viewer side substrate (14) of the liquid crystal drive panel (11) and the liquid crystal alignment direction of the light source side substrate (15) of the optical compensation panel (12) are 8.
I made it so that they intersect at 0 degrees. By doing this, it was possible to obtain a brighter black and white display screen than in the past. Thereafter, the liquid crystal panel and the drive circuit were connected using FPC.

The thus completed liquid crystal electro-optical device has a duty cycle of 24.
0. Driven at a frame frequency of 280 Hz. The liquid crystal panel was then irradiated with white light, and the light that passed through the liquid crystal panel was converted into voltage using a photomultiplier, which was input into an oscilloscope to measure the contrast. Result 8
A high contrast of 4 was obtained. Further, Table 7 shows the results of contrast measurements performed while keeping the duty number constant and changing the frame frequency (240).

Table 7 As can be seen from Table 7, a high contrast of 70 sides was obtained at a frame frequency of 200 Hz. In comparison, only a low contrast could be obtained at frame frequencies of 120 to 180 Hz.

[Example 8] After forming an ITO thin film as a transparent electrode on a first soda glass substrate using a DC sputtering method, a control electrode is produced using a known photolithography method.

Furthermore, scanning electrodes made of ITO are fabricated on a second soda glass substrate in a similar manner.

Then, polyamic acid is sprayed onto the first and second substrates using an offset printing machine, and heated at 300° C. for 3 hours to obtain a polyimide thin film.

Then, the polyimide thin films on both substrates are rubbed using cotton cloth. However, the first substrate and the second
The rubbing directions of the substrates are made to intersect at an angle of 240 degrees.

Then, spherical fine particles (spacers) made of SiO□ with a diameter of 6.2 μm are scattered on one substrate, and an epoxy sealant is screen printed on the other substrate, and the substrates are bonded together.

Thereafter, liquid crystal is injected using a known vacuum injection method to produce a liquid crystal driving panel. However, as it was, the center of the panel was swollen, so a re-pressing process was performed here. In other words, pressure was applied toward the inside of the cell in order to force the excess liquid crystal injected out of the cell. Then, the liquid crystal injection port was sealed using an ultraviolet curing resin to complete a liquid crystal driving panel.

Next, an optical compensation panel is produced.

Third. After spraying polyamic acid on the fourth soda glass substrate using an offset printing machine, heating is performed at 300 degrees for 3 hours to obtain a polyimide thin film.

Then, the polyimide thin films on both substrates are rubbed using cotton cloth. However, the rubbing directions of the third substrate and the fourth substrate are made to intersect at an angle of 240 degrees in the opposite direction to that of the liquid crystal driving panel. Also, the third
The rubbing direction of the second substrate was made to intersect with the rubbing direction of the second substrate of the liquid crystal driving panel at an angle of 80 degrees.

Then, spherical fine particles (spacers) made of SiO□ with a diameter of 7.5 μm are scattered on one substrate, and an epoxy sealing material is screen printed on the other substrate, and the substrates are bonded together.

Thereafter, liquid crystal is injected using a known vacuum injection method to produce an optical compensation panel.

However, the center of the panel was swollen as it was, so a re-pressing process was performed here. In other words, pressure was applied toward the inside of the cell in order to force the excess liquid crystal injected out of the cell.

Then, the liquid crystal injection port was sealed using an ultraviolet curing resin to complete an optical compensation panel.

And polarizing plates (16), (17), light source (20),
A liquid crystal driving panel (12) was arranged as shown in FIG.

As is clear from FIG. 3, the liquid crystal alignment direction of the viewer side substrate (14) of the liquid crystal drive panel (ll) and the liquid crystal alignment direction of the light source side substrate (15) of the optical compensation panel (12)
I made it so that they intersect at 0 degrees.

By doing this, it was possible to obtain a brighter black and white display screen than in the past.

Thereafter, the liquid crystal panel and the drive circuit were connected using FPC.

The thus completed liquid crystal electro-optical device has a duty cycle of 24.
Contrast measurements were performed at frame frequencies of 0 and 60, and at frame frequencies of 280 Hz and 140 Hz, respectively. The results are shown in Table 8. In the table, l/60 means the duty number 60, and 1/240 means the duty number 240.
shows.

Table 8 As is clear from Table 8, driving at a frame frequency of 200Hz to 280Hz as described in the present invention is particularly effective when the duty number becomes large, and when the duty number is as small as about 60, the frequency It can be seen that high contrast is obtained regardless of the

〔Effect of the invention〕

As described above, when driving a liquid crystal electro-optical device with a duty number of 200 sides, it is necessary to
By driving at a frame frequency of 0 to 280 Hz, high contrast can be obtained and the strain on the viewer's eyes can be reduced.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) show infrared waveforms when the present invention is used. FIGS. 2(a) and 2(b) show oscilloscope waveforms when using the conventional technique. FIG. 3 shows the liquid crystal alignment treatment direction and the absorption axis direction of the polarizing plate in this example.

Claims (1)

[Claims] 1. A nematic liquid crystal having positive dielectric anisotropy and added with an optically active substance is sandwiched between a pair of upper and lower electrode substrates arranged opposite each other, and is twisted in the thickness direction in the range of 180 degrees to 270 degrees. When driving a liquid crystal electro-optical device on 200 sides in a time-division manner, the duty number is 2.
A method for driving a liquid crystal electro-optical device, characterized in that the device is driven at a frame frequency of 00 to 280 Hz.