JPH10170888A - Driving method for liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving method that can easily set a delay period, in which it is possible to control to be in an array of liquid crystal corresponding to the ON state and OFF state of a display, by analyzing the behavior of the tilt angle of liquid crystal molecule in the center of a liquid crystal cell after a reset period. SOLUTION: A reset voltage, which is larger than a threshold value, for causing Fredericks transition is applied in the reset period to set the tilt angle of the liquid crystal molecule positioned almost in the center between substrates to a plane parallel to the substrates to almost 90 deg.. A delay voltage is applied to the liquid crystal while the tilt angle of the liquid crystal molecule is at least 100 to 110 deg. in a delay period between the reset period and a selection period. The following selection period is stated when the liquid crystal begins to be relived into one semistable state after a back flow and in this selection period, a select voltage for selecting one of two semistable states is applied to the liquid crystal to perform control into an array of the liquid crystal corresponding to the ON state and OFF state of the display. In a nonselection period following the selection period, a nonselect voltage is applied to the liquid crystal.

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 a bistable liquid crystal display device having a memory property using a nematic liquid crystal.

[0002]

2. Description of the Related Art A bistable liquid crystal display using a nematic liquid crystal has been disclosed in Japanese Patent Publication No. 1-51818, which describes initial alignment conditions, two stable states, and a method of realizing the stable state. I have.

However, the contents described in Japanese Patent Publication No. 1-51818 only describe operations or phenomena in two stable states, but do not suggest means for putting them into practical use as a display. Furthermore, the above-mentioned publication does not describe anything about a matrix display having the highest practical application and the highest display capability as a display body at present, and does not disclose any driving method.

In view of the above, the applicant of the present application has proposed in Japanese Patent Application Laid-Open No. Hei 6-230751 a method for controlling the back flow generated in a liquid crystal cell and improving the above-mentioned disadvantage. In this method, first, a 0 ° uniform state is formed by applying a high voltage of about 1 ms to generate a Freedericksz transition, followed by a constant voltage pulse having a polarity opposite to or the same as that of the pulse immediately after the pulse. Similarly, a pulse period equal to or shorter than the threshold immediately following the Freedericksz transition voltage is provided to realize a 360 ° twist state. In this method, the writing time per line of the matrix display is set to 400 μs, and a total of 160 ms (6.25 Hz) is used for writing over 400 lines.
The above time is required, and this involves display flicker, which still has a practical problem.

Accordingly, the applicant of the present application has further filed Japanese Patent Application Laid-Open No. 7-175041 as an improvement in the writing time. As shown in FIG. 2 or FIG. 4 of the publication, a delay time is provided after a reset pulse causing Freedericks transition, and then an ON or OFF selection signal is applied. In this way, the writing time was several times faster than in the past, for example, 50 μs.

[0006]

SUMMARY OF THE INVENTION Incidentally, Japanese Patent Application Laid-Open No.
According to 175041, it was known that the timing at which the selection pulse should be applied is near the transition point when transitioning to two metastable states, but since it was impossible to actually verify this transition point Then, various experiments in which the delay period and the selection period were changed were performed to confirm whether or not the arrangement of the liquid crystal corresponding to the display ON state / OFF state could be controlled.

Therefore, how to set the delay period with respect to the selection period set based on the duty ratio obtained from the number of driving pixels per frame is determined by performing various experiments with different delay periods. In addition, it was necessary to verify whether the arrangement of the liquid crystal corresponding to the on / off state of the display could be controlled.

Therefore, an object of the present invention is to analyze the behavior of the tilt angle of the liquid crystal molecules at the center of the liquid crystal cell after the reset period, thereby making it possible to easily set the length of the delay period. It is an object of the present invention to provide a driving method of a liquid crystal display device which can appropriately set a start time of a selection period in which an arrangement of liquid crystal corresponding to an on state / off state can be controlled.

[0009]

According to the first aspect of the present invention, the liquid crystal molecules sealed between the substrates have a predetermined twist angle in an initial state, and the liquid crystal molecules are in a relaxed state after a voltage for causing a Freedericksz transition is applied. In a driving method of a liquid crystal display device in which a liquid crystal having two metastable states different from the initial state is used and at least a reset period, a selection period, and a non-selection period are set in one frame period to drive the liquid crystal, a) applying a reset voltage equal to or higher than a threshold value for causing the Freedericksz transition to the liquid crystal during the reset period, and tilting the liquid crystal molecules positioned substantially at the center between the substrates with respect to a plane parallel to the substrate. The angle is almost 90 °,
(B) a delay period between the reset period and the selection period, in which the tilt angle of the liquid crystal molecules located substantially at the center between the substrates is at least 100 to 110 °. (C) applying a selection voltage to the liquid crystal for selecting one of the two metastable states during the selection period after the delay period; In a non-selection period following the selection period, a non-selection voltage is applied to the liquid crystal.

The present inventors have analyzed the behavior of the liquid crystal molecules located at the center of the liquid crystal cell and found the following. First, by applying a voltage during the reset period, the tilt angle of the liquid crystal molecules at the center of the liquid crystal cell becomes substantially 90 °, and the liquid crystal molecules stand almost perpendicular to the substrate. Thereafter, the back flow is started so that the tilt angle of the liquid crystal molecules becomes a larger tilt angle from 90 ° at the time of resetting. As a result of this behavior,
Backflow to a tilt angle larger than the tilt angle corresponding to the transition point where the transition to the two metastable states starts,
It has been found that the maximum angle is between 100 and 110 °, even if it has a width depending on the liquid crystal material.

Therefore, in the present invention, the delay period after the reset period is continued until the tilt angle of the liquid crystal molecules at the center of the liquid crystal cell becomes at least 100 to 110 °. At the start of the selection period set immediately after this delay period, the tilt angle of the liquid crystal molecules at the center of the liquid crystal cell always becomes larger than the tilt corresponding to the transition point, and at an appropriate time before reaching the transition point. A selection period can be started. This makes it possible to reliably set the delay period in which the alignment of the liquid crystal corresponding to the ON / OFF state of the display can be controlled.

According to a second aspect of the present invention, in the first aspect, during the selection period, the tilt angle of the liquid crystal molecules is approximately 9%.
It is characterized in that it is set to include the time when it becomes 5 °.

According to the analysis by the present inventors, the tilt angle when the liquid crystal molecules at the center of the liquid crystal cell reach the transition point is approximately 9 degrees.
It turned out to be 5 °. Therefore, the delay period after the reset period is continued until the tilt angle of the liquid crystal molecules at the center of the liquid crystal cell becomes at least 100 to 110 °. If it is continued until 95 °, the selection voltage can be applied to the liquid crystal near the transition point. By setting such a delay period and a selection period, it is possible to control the arrangement of the liquid crystal corresponding to the display ON / OFF state.

According to a third aspect of the present invention, in the first or second aspect, the length of the delay period is set to 210 μsec to 700 μsec.
sec.

According to the analysis by the present inventors, it is found that the saturation value voltage Vsat and the threshold voltage Vth of the liquid crystal change according to the length of the delay period, and the difference voltage | Vsat−Vth | also changes. Was. By the way, the on-state voltage applied to the liquid crystal is higher than Vsat in order to arrange the liquid crystal corresponding to the on state of the display, and is applied to the liquid crystal in order to arrange the liquid crystal corresponding to the off state of the display. The off-state voltage needs to be lower than Vth, and in order to satisfy both of these conditions at the same time, the difference voltage | Vsat-Vth | is required to be small, and it has been found that the above-described delay period should be set. Therefore, by setting the length of the delay period as described above, it is possible to control the alignment of the liquid crystal corresponding to the display ON / OFF state.

According to a fourth aspect of the present invention, in the third aspect, the length of the delay period is set to 280 μsec to 560 μsec.
It is characterized by having.

In order to reduce the on / off voltage, it is required that the difference voltage | Vsat−Vth | be further smaller. In addition, the saturation voltage Vsat and the threshold voltage Vs
Since th changes depending on the environmental temperature, it is necessary to set a certain temperature margin. When the delay period is set within the above range, the difference voltage | Vsat−Vt
h | is further reduced, and even if the environmental temperature changes, the alignment of the liquid crystal corresponding to the ON / OFF state of the display can be controlled by the low voltage driving even if the environmental temperature changes.

The invention of claim 5 is characterized in that, in claim 1 or 2, when the length of the selection period is 1H = approximately 70 μsec, the length of the delay period is 3H to 10H. .

When 1H = approximately 70 .mu.sec as the selection period set when the duty is 1/240, the length of the delay period is set to 3H to 10H. You can set a delay period.

A sixth aspect of the present invention is characterized in that, in the fifth aspect, the length of the delay period is set to 4H to 8H.

When 1H = approximately 70 μsec as the selection period, the length of the delay period is set to 4H to 8H.
The delay period can be set within the range described in claim 4.

[0022]

Next, an embodiment of the present invention will be described with reference to the drawings.

Structure of Liquid Crystal Cell The liquid crystal material used in each of the examples described below is a nematic liquid crystal (for example, ZLI-3329 manufactured by E. Merck) and an optically active agent (for example, S-811 manufactured by E. Merck). By adding, the helical pitch of the liquid crystal is adjusted to 3 to 4 μm. As shown in FIG.
5, a pattern of a transparent electrode 4 made of ITO is formed,
On each of them, a polyimide alignment film (for example, SP manufactured by Toray Industries, Inc.)
-740) 2 was applied. Then, with respect to each of the polyimide alignment films 2, a predetermined angle φ (φ = 180 in the embodiment).
°) Rubbing treatment was performed in different directions to form cells. A spacer is inserted between the upper and lower glass substrates 5 to make the substrate spacing uniform, for example, the substrate spacing (cell spacing) is set to 2 μm or less. Therefore, the ratio of the liquid crystal layer thickness / twist pitch is 0.5 ± 0.2.

When liquid crystal is injected into this cell, liquid crystal molecules 1
Are several degrees, and the initial orientation is 1
An 80 ° twisted state results. This liquid crystal cell is sandwiched between two polarizing plates 7, 7 having different polarization directions shown in FIG.
An indicator was formed. 3 is an insulating layer, 6 is a flattening layer,
8 is a light-shielding layer between pixels, and 9 is a director vector of the liquid crystal molecules 1. The flattening layer 6 and the light-shielding layer 8 can be formed as needed, and a transparent electrode may be formed on the substrate 5 instead.

A plurality of row electrodes (also referred to as scanning signal electrodes) extending, for example, along the row direction are formed on one substrate 5 as the transparent electrodes 4, for example, as the transparent electrodes 4 on the other substrate 5. A column electrode (also referred to as a data signal electrode) extending in the column direction is formed, and a voltage difference between signals supplied to both electrodes is applied to the liquid crystal layer, and the liquid crystal corresponding to the on / off state of the display is turned on. The drive for controlling the array is performed.

Description of Liquid Crystal Display Device FIG. 7 shows a simple matrix type liquid crystal display device using the liquid crystal cell shown in FIG. In FIG. 7, the liquid crystal display device is of a transmissive type in which a backlight 12 is arranged on the back of a liquid crystal cell 11. A scanning drive circuit 13 is provided on a scanning signal electrode (row electrode) formed on one substrate 5 of the liquid crystal cell 11.
Are connected, and the scan drive circuit 13 is connected to the scan control circuit 15.
Is controlled by On the other hand, the other substrate 5 of the liquid crystal cell 11
A signal drive circuit 14 is connected to the data signal electrodes (column electrodes) formed in the memory cells, and the signal drive circuit 14 is controlled by a signal control circuit 16. A predetermined applied voltage is supplied from the potential setting circuit 17 to the scanning drive circuit 13 and the signal drive circuit 14. Further, a reference clock signal and a predetermined timing signal are supplied from the line sequential scanning circuit 18 to the scanning control circuit 15 and the signal control circuit 16.

Liquid Crystal Driving Principle The signal COM (i) shown in FIG. 2 shows the waveform of the scanning signal supplied to the scanning signal electrode of the i-th row. The signal SEG (j) shown in FIG. 2 shows the waveform of the data signal supplied to the data signal electrode on the j-th column. COM of FIG.
(I) -SEG (j) shows the waveform of the difference signal between the scanning signal and the data signal. The voltage of the difference signal is applied to the liquid crystal of the pixel (i, j) located at the intersection of the i-th scanning signal line and the j-th data signal line.

The drive waveform shown in FIG. 2 has a reset period T
1, delay period T2, selection period T3 and non-selection period T4
It is included. A period obtained by adding the periods T1, T2, T3, and T4 is one frame period T. In this embodiment, the reset period T1 = 1 msec and the delay period T2 = 2
10 μsec, and the selection period T3 is set to 70 μsec. Further, the number of pixels driven during one frame period is 240 and the duty is 1/240, so that 1
Frame period T = 70 μsec × 240 = 16.7 ms
ec.

The scanning signal C0M (i) has a reset potential VR of 15 V or more, for example, 25 V during the reset period.
In the selection period T3, for example, the selection potential Vw is 4V. The delay period T3 is for delaying the start of the selection period T3 after the end of the reset period T1, and the delay potential in that period is 0V. The potential of the non-selection period T4 for holding the voltage charged in the liquid crystal layer during the selection period T3 is also 0V.

The data signal SEG (j) is set to a voltage according to the display state. In the frame shown in FIG. 2, for example, an ON potential (Vd) of 1 V for off-drive and a negative voltage for on-drive of, for example,-. Off potential (-Vd) of 1 V.

It is also possible to invert the polarity of the scanning signal C0M for each frame by inverting the potential of the scanning signal C0M between positive and negative with respect to the intermediate potential of the data signal (0 V in this embodiment).
At the time of the negative drive in this case, Vd becomes the ON potential, and −
Vd becomes the off potential. Note that this polarity inversion drive is performed by 1
The length of the selection period is not limited to every frame, and may be every m (m is an integer) H when the length of the selection period is 1H.

In FIG. 2, the difference signal C applied to the liquid crystal
OM (i) -SEG (j) includes the following various voltages. In the reset period T1, a reset voltage 100 equal to or higher than a threshold value for causing Freedericksz transition in the nematic liquid crystal is applied. This reset voltage 100 is
In this embodiment, the voltage is 24 V or 26 V. In the delay period T2, for example, a voltage of ± 1 V is applied as the delay voltage 110. The selection voltage 1 applied to the liquid crystal cell during the selection period T3
Reference numeral 20 denotes two metastable states of the nematic liquid crystal, for example, 3
The voltage is selected based on a critical value that produces either the 60 ° twist alignment state or the 0 ° uniform alignment state. In the case of the present embodiment, if the selection voltage 120 is the off-state voltage Voff (3 V in this embodiment) that is less than the absolute value of the threshold voltage Vth of the nematic liquid crystal, a 360 ° twist alignment state is obtained. Can be on the other hand,
As the selection voltage 120, the saturation voltage Vsa of the nematic liquid crystal is used.
ON voltage Von exceeding the absolute value of t (5 in this embodiment)
When V) is applied to the liquid crystal cell, a 0 ° uniform alignment state is obtained. In the non-selection period T4, the non-selection voltage 130 equal to or lower than the threshold value that can maintain two metastable states
(± 1 V in this embodiment) is applied, and the state of the liquid crystal selected in the selection period T3 is maintained.

FIG. 3 is an explanatory diagram for explaining various states of the nematic liquid crystal.

In the initial alignment state, the liquid crystal is in a 180 ° twist alignment state by the above-described rubbing treatment. The reset period T is applied to the liquid crystal in the initial alignment state.
When a reset voltage 100 is applied at 1, a Freedericksz transition occurs as shown in FIG. After this, the selection period T3
When an ON voltage Von is applied to the liquid crystal as the selection voltage 120 at 0, a uniform orientation state of 0 ° is obtained, and the OFF voltage V
When off is applied, a 360 ° twist alignment state is obtained. Thereafter, as shown in FIG. 3, the state naturally relaxes from one of the above two states to the initial state according to a certain time constant. Here, this time constant can be made sufficiently longer than the time required for display. Therefore, as long as the non-selection voltage 130 applied in the non-selection period T4 is maintained at a voltage sufficiently lower than the voltage required to cause the Freedericksz transition, the non-selection voltage until the reset period T1 in the next frame. During the period, the state set in the selection period T3 can be substantially maintained. Thereby, a liquid crystal display becomes possible.

Here, the present inventors, as shown in FIG.
Assuming that the gap between the two substrates 5 and 5 is d, the liquid crystal molecules 1 at the center of the liquid crystal cell at a position d / 2 from one substrate 5
We paid attention to the behavior of.

In FIG. 5, the horizontal axis represents time, and the vertical axis represents the tilt angle θm of the liquid crystal molecules 1 at the center of the liquid crystal cell. Here, the tilt angle θm shown in FIGS. 4 and 5 is such that a horizontal line parallel to the substrate 5 is 0 ° and a counterclockwise rotation angle in a plane parallel to the paper is a positive tilt angle. In FIG. 5,
The tilt angle of the upper and lower liquid crystal molecules adjacent to the two substrates is 0 °
However, in practice, a certain positive tilt angle is obtained by the rubbing process.

In FIG. 5, when a reset pulse 100 equal to or more than a threshold value for causing the Freedericksz transition is applied to the liquid crystal, the tilt angle θ of the liquid crystal molecules 1 at the center of the liquid crystal cell is increased.
m is substantially 90 °, and the state is perpendicular to the substrate 5 (homeotropic orientation state).

Then, as shown in FIG. 5, the liquid crystal molecules 1 at the center of the liquid crystal cell from the time when the reset pulse 100 is cut off.
Starts falling in a direction in which the tilt angle θm exceeds 90 °.
This phenomenon is called a backflow.

Thereafter, the liquid crystal molecules 1 at the center of the liquid crystal cell have the tilt angle θm of 90 degrees again at the transition point A shown in FIG.
Then, depending on the magnitude of the applied voltage, the tilt angle θm is divided into a direction in which the tilt angle θm is 0 ° and a direction in which the tilt angle θm is 180 °. The former is a transition to a 0 ° uniform orientation state, and the latter is equivalent to a transition to a 360 ° twist orientation state because a twist is added in addition to the change in the tilt angle θm.

By the way, immediately after the reset pulse 100 has expired, the back flow of the liquid crystal is called either the transition to the 0 ° uniform alignment state or the transition to the 360 ° twist alignment state, as is apparent from FIG. The behavior is completely the same at the point reaching the transition point A through the same process. In other words, the tilt angle θ larger than the tilt angle θm corresponding to the transition point A due to the back flow of the liquid crystal molecules 1 at the center of the cell.
m always exists.

What is important here is that the selection period T3 is set including the transition point A, which is the timing at which the trigger (selection voltage) after the backflow of the liquid crystal occurs should be applied. Even if the selection period ends earlier than the transition point A, or if the selection period starts later than the transition point A, the liquid crystal cannot be turned on and off.

Even if the selection period T3 is set including the transition point A, if the selection period T3 is started too early, the length of the selection period becomes longer, and the pixel of one line High-speed driving in a liquid crystal display device having a large number and a small duty becomes impossible.

For this purpose, it is important to ensure that the selection period T3 starts just before the transition point A, that is, when the delay period T2 ends.

In this embodiment, after the reset period T1, the tilt angle θ larger than the tilt angle θm corresponding to the transition point A due to the back flow of the liquid crystal molecules at the center of the liquid crystal cell.
The delay period T2 is continued until m. As a result, the selection period T3 started after the delay period T2
Starts when the liquid crystal molecules at the center of the liquid crystal cell have a tilt angle θm larger than the tilt angle θm corresponding to the transition point A.

According to the present inventors, it has been found that the tilt angle θm that is larger than the tilt angle θm corresponding to the transition point A is 100 to 110 °, even if it has a width depending on the liquid crystal material.

Therefore, in this embodiment, the reset period T1
The subsequent delay period T2 is continued until the tilt angle θm of the liquid crystal molecules at the center of the liquid crystal cell becomes at least 100 to 110 °. At the start of the selection period T3 set immediately after the delay period T2, the tilt angle θm of the liquid crystal molecules at the center of the liquid crystal cell always becomes larger than the tilt angle θm corresponding to the transition point A. T3 can be started.

According to the present inventors, the tilt angle θm when the liquid crystal molecules at the center of the liquid crystal cell reach the transition point A is:
It turned out to be about 95 °. Therefore, the delay period T2 after the reset period T1 is continued until the tilt angle θm of the liquid crystal molecules at the center of the liquid crystal cell becomes at least 100 to 110 °, and the subsequent selection period T3 is set at the center of the liquid crystal molecules at the center of the liquid crystal cell. If it is continued until the tilt angle θm becomes approximately 95 °, the selection pulse 12
0 can be applied.

Here, the selection pulse 120 applied during the selection period T3 needs to have a certain effective value or more, and when the voltage value of the selection pulse is low, the application time is lengthened, and conversely, the application time is increased. When the voltage value is high, the application time is short.

From the above considerations, as the selection period T3,
The tilt angle θm of the liquid crystal molecules at the center of the liquid crystal cell is at least 1
5 can be set within the period t shown in FIG.
3 must be included.

Next, the length of the delay period T2 will be considered. FIG. 6 is a characteristic diagram showing a relationship between the saturation value Vsat of the nematic liquid crystal, the threshold value Vth, and the delay period T2. The saturation value Vsat and threshold value Vth of the liquid crystal change according to the length of the delay period T2. The saturation value Vs of this liquid crystal
At and the threshold value Vth both become the minimum values when the delay period T2 is set to a predetermined length, and increase at different rates from that point. Therefore, as is apparent from FIG. 6, the voltage difference | Vsat−Vth | between the saturation value Vsat and the threshold value Vth of the liquid crystal also changes according to the length of the delay period T2, and as shown in the range B of FIG. Difference | Vsat
-Vth | is small.

Here, the ON voltage Von for turning on the nematic liquid crystal must satisfy Von = Vw + Vd> Vsat, and at the same time, the off voltage Voff for turning off the nematic liquid crystal is as follows: Voff = Vw−Vd < Vth must be satisfied.

In order to control the alignment of the liquid crystal corresponding to the on / off state of the display, the above two conditions must be satisfied at the same time. In general, the scanning potential Vw and the data It can be seen that there is a range in the length of the delay period T2 in order to satisfy both conditions with the potential Vd. For example, in this embodiment, since Vw = 4 × Vd, Von = 5 × Vd> Vsat and Voff = 3 × Vd.
In order to satisfy Vd <Vth, at least | Vsat−
Vth | <2 × Vd, and the delay time T that satisfies the value of | Vsat−Vth |
2 must be selected.

According to the present inventors, if the length of the selection period T3 is set to 70 μsec and defined as 1H, the preferable range of the delay period T2 is 3H to 10H. When the delay period T2 is, for example, 2H below the lower limit or 11H above the upper limit, the voltage difference | Vs between the saturation value Vsat of the liquid crystal and the threshold value Vth.
at-Vth | was too large to satisfy both conditions.

More preferably, the saturation value Vsat of the liquid crystal is
When the delay period T2 is determined in a range where the voltage difference | Vsat−Vth | between the threshold value and the threshold value Vth is substantially the minimum value, the delay period T2 is 4H to 8H. If the delay period is set in this range, the voltage difference | Vsat−Vth | is small, and therefore, the saturation value Vsat of the liquid crystal and the threshold V
Even if th fluctuates, the temperature margin that satisfies the above two conditions is widened. Also, the voltage difference | Vsat-V
is small, there is also an advantage that the on / off voltage can be reduced.

When the above is defined by the absolute time of the delay period T2, it is preferably 210 μsec to 700 μsec.
c, more preferably 280 μsec to 560
μsec. The length of the selection period T3 is set to 70 μs.
Even when the delay time is set to a value other than ec, the above-described delay period T3 expressed in absolute time can be applied.

[0056]

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a structure of a liquid crystal cell of an embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a liquid crystal driving waveform diagram showing an example of a driving method of the present invention.

FIG. 3 is a schematic explanatory diagram for explaining the behavior of liquid crystal molecules in the liquid crystal cost-in-use apparatus used in the present invention.

FIG. 4 is a schematic explanatory view for explaining a tilt angle of liquid crystal molecules at the center of a liquid crystal cell.

5 is a characteristic diagram showing a change in tilt angle of each liquid crystal molecule in the center of the liquid crystal cell shown in FIG. 4 during each period.

FIG. 6 is a characteristic diagram showing a relationship between a saturation value voltage and a threshold voltage of a liquid crystal and a delay period.

FIG. 7 is a block diagram illustrating an example of a liquid crystal display device according to the present invention.

[Explanation of symbols]

 T1 reset period T2 delay period T3 selection period T4 non-selection period Vsat saturation value voltage Vth threshold voltage 1 liquid crystal molecule 2 polyimide alignment film 5 glass substrate 7 polarizing plate 11 liquid crystal cell 12 backlight 13 scan drive circuit 14 signal drive circuit 15 Scanning control circuit 16 signal control circuit 17 potential setting circuit 18 line sequential scanning circuit 100 reset voltage 110 delay voltage 120 selection voltage 130 non-selection voltage

Claims (7)

[Claims] A liquid crystal molecule sealed between substrates has a predetermined twist angle in an initial state, and has two metastable states different from the initial state as a relaxed state after applying a voltage for causing a Freedericksz transition. A method of driving a liquid crystal display device that drives a liquid crystal by setting a reset period, a selection period, and a non-selection period during at least one frame period using a liquid crystal having a state, wherein: (a) the Freedericksz transition occurs during the reset period; A reset voltage equal to or higher than a threshold value for applying the liquid crystal is applied to the liquid crystal so that the tilt angle of the liquid crystal molecules located substantially at the center between the substrates with respect to a plane parallel to the substrate is substantially 90 °.
(B) a delay period between the reset period and the selection period, until the tilt angle of the liquid crystal molecules located at substantially the center between the substrates becomes at least 100 to 110 °. Applying a delay voltage to the liquid crystal; (c) applying a selection voltage to select one of the two metastable states to the liquid crystal during the selection period after the delay period; A method for driving a liquid crystal display device, wherein a non-selection voltage is applied to the liquid crystal during a non-selection period following the selection period. 2. The method according to claim 1, wherein the selection period is set including a time when the tilt angle of the liquid crystal molecules becomes approximately 95 °. 3. The method according to claim 1, wherein the length of the delay period is from 210 μsec to 700 μsec.
c. A method for driving a liquid crystal display device, the method comprising: 4. The method according to claim 3, wherein the length of the delay period is 280 μsec to 560 μsec.
c. A method for driving a liquid crystal display device, the method comprising: 5. The liquid crystal display device according to claim 1, wherein when the length of the selection period is 1H = about 70 μsec, the length of the delay period is 3H to 10H. Method. 6. The method according to claim 5, wherein the length of the delay period is 4H to 8H. 7. The driving method of a liquid crystal display device according to claim 1, wherein the delay voltage is equal to or less than a voltage applied to the liquid crystal during the non-selection period.