JPS6118931A - Liquid-crystal display device - Google Patents

Abstract

PURPOSE:To manufacture a large-capacity device at low cost by providing cells which have ferroelectric liquid crystal between mutually parallel transparent substrates between two upper and lower polarizing plates, varying a molecule array with a DC voltage, and fixing the molecule array with an AC voltage. CONSTITUTION:Liquid-crystal cells which have ferroelectric liquid crystal of a chiral smetic C phase between mutually parallel transparent substrates are arranged in a matrix between two upper and lower polarizing plates to form an LC panel. Then, a display electrode driver circuit and a scanning electrode driver circuit are scanned in the X-axial and Y-axial directions with the output of a control circuit. Driving voltages of both driver circuits depend upon the output of a driving voltage generating circuit controlled by the control circuit. When the driving voltages are direct currents, the molecule array is varied to make a bright-to-dark or dark-to-bright change according to the polarity, and when AC driving is performed, the molecule array becomes constant and the current display state is held constant. Thus, the large-capacity panel is manufactured at low cost.

Description

[Detailed Description of the Invention] [Field of Industrial Application] Liquid crystal display devices have advantages such as being able to be driven at low voltage, consuming extremely low power, and being able to be manufactured in a thin and compact size, and are used in mobile devices such as watches and calculators. Widely used for displaying small devices. In recent years, as liquid crystal display devices have become larger in area and capacity, and with the development of 0MO8-LSI in the semiconductor field, liquid crystal display devices have been applied to office automation equipment such as personal computers. . from now on,
It is thought that liquid crystal display devices will be introduced into various information processing devices by taking advantage of the advantage that they can be directly driven by 0MO8-IC. In this case, an important technical issue facing liquid crystal display devices is how to achieve display capacity and response speed equivalent to those of CRTs. The present invention provides means for realizing a large-sized, large-capacity, fast-response liquid crystal display device that is highly useful as advanced information processing terminal equipment such as office automation equipment.

[Prior art]

The liquid crystal conventionally used in displays is thermotropic liquid crystal. Thermotropic liquid crystals take on various liquid crystal phases depending on the temperature range, depending on the material.
It is classified into a smectic phase (hereinafter referred to as N) and a smectic phase having a layered structure (hereinafter referred to as Sm).

am is further a uniaxial smectic A phase (hereinafter referred to as smA)
It is classified as a biaxial smectic C phase (ismo). The thickness of the layer roughly corresponds to the length of one liquid crystal molecule.

FIG. 1 schematically shows the molecular arrangement of N, BmA, and SmO. Figure 1 a is N, Figure 1 is E! mA.

Figure 1C shows SmO.

Furthermore, if the liquid crystal molecules have an asymmetric carbon and are not racemic, they will live in a helical structure.

In the case of N, the long axes of liquid crystal molecules are located within the thin layer and are aligned in one direction.

This results in a chiral nematic structure in which the direction of the molecules within each layer is slightly twisted in each layer. FIG. 2 is a diagram schematically showing the molecular arrangement of chiral nematic. In the case of Sm, the molecules are arranged in a spiral with the normal direction of the layer as the helical axis, resulting in a chiral smectic C phase (hereinafter referred to as S m O'').

FIG. 3a is a diagram schematically showing the molecular arrangement of SmO''.

Let me explain SmO* in a little more detail.

Long axis direction of liquid crystal molecules in one layer (hereinafter referred to as molecular axis)
is inclined by an angle θ with respect to the normal direction of the layer, and this angle is one foot for every layer.

FIG. 3b shows the relationship between the molecular axis and the normal direction.

On the other hand, when looking at the molecular arrangement of SmO* from the normal direction of the layer, the azimuth angle ψ rotates by one foot (a in Figure 3 shows the case where it changes by 45 degrees) for each layer. However, the molecular arrangement results in a helical structure.

In general, S m O* not only has a completely helical structure but also exhibits ferroelectricity with an electric dipole in the direction perpendicular to the molecular axis.

Ferroelectric liquid crystal was developed in 1975 by Meyer (J, de.
Phys.

It was synthesized and its existence was demonstrated by Ding τ, 69, 1975).

The -fc liquid crystal synthesized at that time is commonly known as IJOBAMBO (2
-Methylbutyl p-[(P-n-decyloxybenzylidene)amino]) Ps O,oE,, 0QOH=N<Q>O)]=OH000
0H, OHO, II.

It is still actively used in research on ferroelectric liquid crystals.

S+nC* has a helical structure as described above, but the period of the helix varies depending on the liquid crystal and is usually about several μm.

When a liquid crystal of SmC''k is injected into a cell having a gap of about 1 μm, which is thinner than the period of the helix, the helical structure disappears.

The molecular arrangement structure after the helical structure disappears is shown in FIG. 4 together with the geometric relationship with the cell substrate.

The liquid crystal molecules become parallel to the cell substrate. That is,
The liquid crystal molecules are arranged with their molecular axes parallel to the substrate and tilted by θ from the layer normal direction. Here, the normal direction of the layer is parallel to the substrate.

The scattering layer is formed perpendicular to the substrate. When tilted by θ from the normal direction of the layer, there are domains that are tilted 10 degrees clockwise from the normal and domains that are tilted 10 degrees counterclockwise from the normal.

SmO" liquid crystal molecules generally have electric dipoles perpendicular to the molecular axis. If the electric dipoles are aligned upward with respect to the cell substrate in one domain, the electric dipoles are aligned downward in the other domain. When an electric field is applied between the cell substrates, the liquid crystal molecules in the entire cell will move by 10 or 10 (+) from the normal direction of the layers.

- is determined by the direction of the electric dipole. )
Align in the tilted position. From now on, these positions will be changed to +θ position and -
It is called ○ position.

When an electric field is applied opposite to the above, the liquid crystal molecules move from the 10th position to the 10th position, or from the 10th position to the 10th position. This phase structure is SmO because the molecules throughout the cell are arranged in the 10 or 10 positions. By thinning the cell gap, the helical structure disappeared and an SmC phase was formed.

However, this SmO, as a trace of its helical structure, moves along the cone shown in FIG. 6b when moving from the ±θ position to the opposite position.

・Ordinary SmO does not undergo such movement even when an electric field is applied.

This cell can be used as a display system by appropriately selecting the polarity of the electric field, moving the liquid crystal molecules between the 10th and 10th positions, and pasting polarizers on the two cell substrates. .

FIG. 5 is a diagram showing the relationship between two polarizers and ten positions of liquid crystal molecules when used in a display element.

In Fig. 5a, the polarization axis of the polarizer on the incident side is aligned with the 10 position. The polarizer on the output side is rotated by a total of 90 degrees of polarization axis from the polarization axis of the polarizer on the input side.

In case a of Fig. 5, if there is a liquid crystal molecule at position 10, 1. The light polarized by the polarizer on the input side reaches the polarizer on the output side without changing its polarization direction, but since the photons on both sides are perpendicular to each other, no light is emitted to the output side.

This state is a dark state. Conversely, when the liquid crystal molecules move to position 10, the birefringence of the liquid crystal causes light to be emitted also in the direction of the polarizer orthogonal to the output side.

If θ is 22.5° and the cell thickness is an appropriate value, most of the light will be directed in the polarization direction of the output side polarizer, resulting in a bright state.

In order to obtain the ideal display state as mentioned above, the cell thickness d
The following relationship is required between and the refractive index anisotropy Δn of the liquid crystal.

d=(2n-1)α/△n n: refractive index α=
Cπ/ω C: Speed of light dust, ω The angular frequency of light b in Figure 5 is,
This is a case where the directions of the polarizers on the incident side and the output side are the same.

The 10th position becomes a bright state, and the -0 position becomes a dark state. The relationship between the cell thickness and Δn is the same as the above equation. θ=22
．． Ideal bright and dark conditions can be achieved at 5°.

The idea behind this display element is based on 01ark and LgerWal.
l(Appl, Prys, 1ett, 36, 899
, 1980) et al.

They claimed that a display element with thinner cells and two polarizers attached had the following characteristics.

In other words, (1) Fast response on the μ-order order (2) 11 memos (3) Desired threshold characteristics Among these characteristics, fast response has been confirmed in our observations and measurements, and the response is on the μ-order order. It shows.

In addition, after applying an electric field to any of the 10 positions, the state will be maintained even if the field is turned off.
Gender exists as they claim.

However, the desired threshold properties could not be confirmed in our observations.

FIG. 6 shows the relationship between strong optical transmission and applied voltage V when a threshold characteristic exists.

When the applied voltage is below vth, the molecules do not move at all and the intensity of the optically transmitted light changes rapidly.

When a voltage higher than vth is applied, the molecules begin to move. At that time, the optically transmitted light intensity changes sharply depending on the applied voltage.

When the applied voltage becomes larger than Vsatj, the optically transmitted light intensity does not change any further. In other words, the molecule is fixed at the θ position.

The above vth and Vsat are parameters representing threshold characteristics.

According to our data, Vth and Vsat are Vth
=500 (mV) Vsat = s (v). (Measured with DOBAMBO) ``Considering the case of driving, it is impossible to drive so that a voltage of 5V is applied to the selected point and a voltage of 500 (mV) or less is applied to the non-selected and half-selected points.

[Purpose of the invention]

The purpose of the present invention is to present a new display principle and driving method using SmO* liquid crystal for time-divisional driving, and to enable a full range of multi-segment liquid crystal displays that could not be realized with the TN type liquid crystal display system. .

[Structure of the invention]

The details of the present invention will be explained below with reference to Examples.

For those who understand the principle of the present invention, it is worth noting that a DC voltage is first applied to a panel in which the cell thickness is reduced to about 1 μm and a polarizer is arranged as shown in Figure 5a, and then an AC pulse is applied. The change in optical transmission intensity fr must be accounted for.

FIG. 7 shows the change in optical transmission intensity when the above voltage waveform is applied.

The vertical axis on the left represents optical transmission intensity.

The fallout is the optical transmission intensity when a voltage higher than Vsa is applied and the panel sandwiched between orthogonal polarizers blocks most of the incident light.

(2) OR is the optical transmission intensity when the panel transmits the most light when a voltage of opposite polarity higher than Vsat is applied.

In FIG. 7, the polarity and voltage value of the DC voltage were selected so that the optical transmission intensity was ON.

When a DC voltage of 15V is applied to turn the optical transmission intensity ON, and then an AC pulse of ±5V is applied, the optical transmission intensity changes while oscillating. The optical transmission intensity converged to 0.

Although Ic is slightly smaller than IoN, it can be used for display as a black level (dark level).

Conversely, if a DC voltage of opposite polarity is applied to obtain l0FF'e, and then an AC pulse of ±5V is applied, the optical transmission intensity will oscillate from Iovy to 1? The optical transmission intensity converged to C'.

In this case as well, although it is slightly thicker than IC' ij I oyy, it can be used for display as a white level (bright level).

FIG. 8 is a diagram showing the change in optical transmission intensity when the frequency and voltage amplitude of the AC pulse of the applied voltage waveform are changed.

First, when the frequency was changed, three optical transmission intensity profiles at the top of FIG. 8 were observed.

Between the frequency fl * fl + f3, fI>f2>
There is a relationship.

The higher the frequency of the AC pulse, the more difficult it is to attenuate, and the higher the convergent optical transmission intensity IC becomes.

Furthermore, when the voltage amplitude of the AC pulse was changed, the three optical transmission intensity profiles shown at the bottom of FIG. 8 were observed.

In this case, between voltage amplitude V1 * v2 # vB 1 (
is V, (V, <V.

There is a relationship between

The smaller the voltage amplitude of the AC pulse is, the more it is attenuated and the convergent optical transmission intensity Ic also becomes higher.

The present invention attempts to perform display by changing the display state using a DC voltage and then maintaining the display state using an AC voltage.

That is, at the molecular level, the liquid crystal molecules are moved to the 100 position or the -0 position by a DC voltage or a DC pulse, and then the liquid crystal molecules are kept near the +θ position or the -0 position by an AC pulse to perform display.

FIG. 9 is a diagram schematically showing the position of one molecule when displayed according to the present invention.

When a DC voltage or DC pulse is applied, the molecule moves to a in Figure 9.
It is also considered that it moves to the position tia' (position 10), then moves while vibrating gradually due to the alternating current pulse, and converges at position b or b'.

The position of b or b' is greatly influenced by the cell thickness, orientation, voltage width and frequency of the AC pulse.

Expressing the present invention by focusing on molecules, display is performed using the state of molecules that are not parallel to the substrate other than the 10 positions that are parallel to the substrate.

This is a completely new display principle.

When this principle is applied to time-division driving and line-sequential scanning is performed,
An example of the driving waveform applied to the liquid crystal is a in the 10th direction,
Shown in b.

In one embodiment, the electrodes are of an X-Y matrix type. Further, the potential is expressed as a reference for the entire scanning electrode side.

A and b in FIG. 10 are voltages applied to one pixel on the first scanning electrode of the xy matrix electrode.

In the present invention, the brightness/darkness of a pixel is also determined by the polarizer and molecular position shown in FIG. 5. If the polarizer is reversed to a in Figure 5 (that is, the polarization axis of the polarizer on the output side is aligned with the 10 position, and the polarization axis of the polarizer on the input side is arranged so as to be perpendicular to each other), the brightness and Darkness is reversed.

The position of a molecule is determined by the direction of the electric dipole in the molecule, so it is determined by the direction of the voltage applied to the pixel (direction of the electric field), but the pixel can be made either bright or dark depending on the placement of the polarizer.

Therefore, the state obtained by the two drive waveforms a and b in FIG. 10 can be either bright/dark or dark/bright. For the sake of simplicity, it is assumed that FIG. 10a provides a dark state and FIG. 10S provides a bright state.

The vibration waveform a in FIG. 10 has been subjected to line sequential scanning,
At the selection timing, the display electrode has a positive potential Vapp with respect to the scanning electrode, then becomes a negative potential of %Vap, and then becomes an alternating current pulse at the non-selection timing.

In addition, the drive waveform in FIG. 10 takes %Vap at the timing when the drive waveform a becomes a positive potential Vap (when we refer to positive and negative potentials, we will refer to the scanning electrode potential from now on),
At the timing when drive waveform a continues to take one false Vap, %
After taking Vapi, it becomes an AC pulse.

Then, at the next timing when the scanning electrode is selected, the negative potential Vap is applied, followed by 'A Vap k, and then an alternating current pulse is generated.

The drive waveform a in FIG. 10 becomes -% Vap at the timing when the drive waveform takes -Vap and then 1Vap.

In a and b of FIG. 10, bright and dark colors are written in pixels by scanning the scanning electrode twice.

One frame in which light and dark are written in the drive shown in FIG. 10 corresponds to 27 Rems in normal line sequential scanning. The scan for writing dark is called a first scan, and the scan for writing light is called a second scan.

When a high voltage Vap is applied to the ferroelectric liquid crystal molecules driven by the driving waveforms a and b in FIG.
It is thought that it moves to position a or a' in the figure or a place close to that position, and then vibrates at position b or b' with equal positive and negative alternating voltages.

In this case, in order to select the driving frequency of the driving waveform, the voltage must be set so that the seven liquid crystal molecules can sufficiently act on the positions e and al in FIG. 9 with a high voltage Vap.

That is, assuming that the drive frequency '(zfD) is on the response time of the liquid crystal molecules at Vap, the following relationship must hold.

τ<172fn Furthermore, there is the following linear relationship between response time and voltage.

"Rainbow r'"PsV Ma: Rotational viscosity Ps: Spontaneous polarization d: Cell thickness Here, η, Ps, and d are considered constants, so τ
ac1/v.

FIG. 11 is a log-log graph representing the relationship between response measurement data and voltage.

The measurement data is almost a straight line, and the above τoc1/v
It can be seen that the relationship holds true.

If the high voltage Vap is increased, the response becomes faster and the motor moves to positions a and a' in Fig. 9 in a short time, so τ≦1.
/2fD, the driving frequency can be increased.0 Set an appropriate driving frequency and driving voltage within a range that does not deteriorate the display condition depending on the type of driving element or the type of display (for example, fixed display or moving image display). Just call.

FIGS. 12, 13, and 14 show three examples of signals used during the first scan in one frame of FIG. 10.

Suwachi, φY! = Selected scanning electrode signal φYl: Non-selected scanning electrode signal φx! = Selected display electrode signal φx! : Non-select display electrode signal It is.

Combine these signals and apply a positive V to create a dark state.
ap f pixel and then apply an alternating current pulse with an amplitude of %Vap.

FIGS. 15, 16, and 17 show three examples of signals used during the second scan in one frame of FIG. 10.

That is, φYd: Selected scanning electrode signal φYd: Non-selected scanning electrode signal φxd: Selected display electrode signal φxd: Non-selected display electrode signal These signals are combined, a negative Vap is applied to put the pixel in a dark state, and then Apply an alternating current pulse with an amplitude of 1 AVap.

Among these signals, Fig. 12, Fig. 13, Fig. 15,
Although FIG. 16 shows a DC pulse, FIGS. 14 and 17 include an AC pulse.

The signals actually used are φY, φY, and φX, which are a combination of any one of the signals shown in FIGS. 12 to 14 and any one of the signals shown in FIGS. 15 to 17.

Create φX.

The signal in FIG. 12 is used as the wc1 scanning signal, the signal in FIG. 15 is used as the second scanning signal, and the two are connected to φr,';l.
Figure 18 (a) shows an example of creating x, φx, and x.
Shown below. In this case, two scans (first scan and second scan)
φx of the second scan for common use in display data
a, φXa were reversed to obtain φX and ix signals.

FIG. 18(b) shows waveforms applied to selected pixels and non-selected pixels in the first scan. φX−φ! for the selected pixel. DC current is applied to non-selected pixels, and φX-φT and φ1-φ7
The exchange will be added. FIG. 18(C) shows waveforms applied to selected pixels and non-selected pixels in the second scan.

FIG. 19 shows an example of a voltage waveform applied to the scan electrode using φY, Jy, φx, and cfix and a voltage waveform applied to the display electrode based on display data.

The voltage waveform a in FIG. 19 is the voltage waveform applied to the scanning electrode, and at the timing of the line sequential scanning signal (select) high level (selection), the selection (scanning electrode signal φY=i) in FIG. The unselected scanning electrode signal φ in FIG.
It is formed by selecting Y.

A voltage waveform C in FIG. 19 is a voltage waveform applied to the display electrodes. The voltage waveform ρ has display data d at H1gh level (
At the timing of the dark state data), the selected display electrode signal φXf in FIG. 18 is selected, and at the timing of the low level, the first
It is formed by selecting the non-selected display electrode signal φxf in FIG.

When the voltage waveforms >z' and a in FIG. 19 are applied to the scan electrode and the display electrode, respectively, the change in the display electrode potential with respect to the scan electrode becomes the drive waveform a in FIG. 10.

The driving waveforms a and b in FIG. 10 are set to ±Vap during the first half of the time when the scanning electrode is selected, and the remaining time is an AC pulse with an amplitude of %Vap. 1
The voltage waveform shown in Figure 7 is considered.

Next, a circuit for realizing the driving method according to the present invention will be described by showing an example.

FIG. 20 is an embodiment of a block diagram of a display device configured with a circuit and an LO panel for realizing the driving method according to the present invention.

This display device includes an oscillation circuit, a control circuit, a drive voltage generation circuit, a display electrode driver circuit, a scan electrode driver circuit, and an LO panel.

21 and 22 are circuit diagrams specifically showing the driving voltage generation circuit, display electrode driver circuit, and scanning electrode driver circuit in FIG. 20. This is an example using a transmission gate.

The drive voltage generation circuit shown in FIG.
The voltage waveform shown in FIG. 5 is applied, and then φY, φY, φX, and moxibustion X shown in FIG. 18 are formed.

Signal M is a drive signal formed by a control circuit,
Using this signal, the voltage waveforms shown in FIGS. 12 and 15 are formed by the transmission gate switch, and then the drive signal shown in FIG. 12 and the voltage waveform shown in FIG. Switching the drive signal shown in the figure, φd.

φY, φX, and φX are formed.

FIG. 23 shows a timing chart of the drive signal M and the scan switching signal FL.

FIG. 22 shows φx, cf formed by the drive voltage generation circuit.
ix, φx, 4xf, scanning signal 00141, 00M2
etc. and display data signals 81BG1, S]1CG2, select φy, iy and φI, 7″Xf respectively and set L
This is an example of a driver circuit for supplying scan electrodes and display electrodes of an O panel.

This driver circuit has been shown here as an embodiment composed of a transmission gate.

The driving method described above generally takes ±Vap i during the first half of the time when the scanning electrode is selected, and then
The voltage waveform can be considered to be an alternating current pulse with an amplitude of 1/N Vap.

When the scanning signal is low level, that is, when not selected, 1/N
When using the general driving method described above in which an AC pulse with the amplitude of Vap is used, the driving waveform applied to the liquid crystal is
Shown in Figure 4 a and b.

However, in the case of a, bVi, for example a in Fig. 24, when selected by the scanning signal in the second scan, (2/N-1) Vap
Take the voltage.

Similarly, in the case of Fig. 24b, only the first half of the time selected by the scanning signal in the first scan (1-
2/N) Take the voltage Vop.

In this way, by moving the liquid crystal molecules to positions a and a' in Figure 9 with a high voltage of ±Vap, the 'fl 1/NV
An alternating current pulse with an amplitude of ap is applied to maintain the display state. In this case, the larger N is, the smaller the amplitude of the alternating current pulse shown in FIG. , ±(1-2/N) V when a scanning signal other than ±Vap is applied (referred to as quasi-selection).
A voltage ap is applied, and its polarity is opposite to ±Vap.

The liquid crystal molecules are voltmeters (1-2/IVap
This causes the image to move in the direction of creating the opposite contrast.

When the liquid crystal is driven with the drive waveform a shown in FIG. 24, the optical transmission intensity increases as 0 in FIG.

N is appropriately selected depending on the material, orientation, etc. of the liquid crystal.

When N is 4, each signal in the first scan and second scan,
φy*, iyl, φxi, φXj and φYd, φY(L
.

The examples of φxa and positive Xd are respectively
It is shown in FIG. 7 and FIGS. 28 to 30.

[Other Examples]

Next, a fC two line sequential driving method, which is different from the above driving method, will be explained.

First, at a selection timing immediately before the timing selected by the scanning signal, a voltage is applied so that all the pixels on the scanning electrode are brought into a bright or dark state.

The timing is shown in FIGS. 31a and 6.

C in FIG. 31 is a normal scanning signal. d in Figure 31
is the scan signal of the scan electrode immediately before the scan electrode selected by the scan signal C. At the H1gh level in FIG. 31d, a high voltage of the same polarity is applied to the scan electrode to which the scan signal a should originally be input so that all the pixels on the scan electrode become bright or dark.

Thereafter, when selecting the original scanning signal, the bright/dark state of the pixel is determined by whether or not a sufficiently high voltage of opposite polarity is applied.

FIGS. 31a and 31b show an example of driving waveforms applied to the liquid crystal when this driving method is used.

When the signal d in Fig. 31 is at the H1gh level, sufficiently high voltages -Vap and -%Vap are applied to the liquid crystal for both drive waveforms a and b, and then when the signal C is at the light level, a sufficiently high voltage is applied to the drive waveform a. Vap is selected and applied to the liquid crystal. Further, at this time, a voltage of %Vap is selected as the drive waveform and applied to the liquid crystal.

Changes in optical transmission intensity when these driving waveforms are applied are shown in a and b of FIG. 32.

A and b in FIG. 32 are a and b in FIG. 61, respectively.

This is a change in optical transmission intensity corresponding to the driving waveform in b.

The optical transmission intensity obtained by driving waveform a in FIG. .

Then, the optical transmission intensity gradually increases due to the alternating current pulse and converges to a certain value.

When the next voltage of -Vap is applied, the optical transmission intensity similarly reaches 1oyy4 or close to it, and then the
When the voltage Vap is applied, it reaches or near OM, and then gradually increases due to the alternating current pulse.

The display becomes dark while going through the above optical changes.

Due to the change in optical transmission intensity due to the driving waveform shown in Fig. 31,
-When 粍Vap is applied, ■011P or near it! ! It then gradually decreases due to the AC pulse and converges to a constant value.

While the optical transmission intensity repeats this change, the display becomes bright.

Basic signal φY applied to the scanning electrode/display electrode to apply the driving waveforms a and b in Fig. 31 to the liquid crystal.
, </IY, φY+1. Examples of φx and 'fx are shown in FIGS. 53 and 34.

φyJy, φx, Tsukasa x, as explained above, but φ
G1 is a signal that is applied so that all pixels on the electrode immediately ahead of the electrode being scanned are in a bright state, regardless of display data.

FIG. 35 shows voltage waveforms applied to the scanning electrodes and display electrodes using the signals shown in FIG. 33.

A voltage waveform a in FIG. 65 is a voltage waveform applied to the scanning electrode, and a voltage waveform d is a voltage waveform applied to the display electrode according to display data.

The signal S in FIG. 35 is a signal indicating the timing of scanning the scanning electrode one scanning electrode before the scanning electrode when focusing on one scanning electrode. When this signal is at the H1gh level, the φY-11 signal is applied to the scanning electrode of interest. 35th
Signal d in the figure is the scanning signal of the scanning electrode of interest, and is the Big level of this signal.

At the timing of , the φY times signal is applied to the scanning electrode.

When voltage waveforms a and bk in Figure 27 are applied to the scanning electrode and the θ display electrode, the voltage change applied to the liquid crystal with reference to the scanning electrode potential becomes drive waveform a in Figure 27.

The bias of the signals in Figs. 55 and 34 is expressed in general terms, and the 66th one is expressed in terms of voltage changes applied to the liquid crystal.
37. FIG.

Drive waveforms a and b in FIG. 36 are -Vap and -
A voltage (1-2/N) Vap is applied to the liquid crystal, moving the liquid crystal molecules to a position where a bright state is obtained.

-Vap, -(i-2/N) Vap is a voltage generated when the display data on the scan electrode immediately before the scan electrode of interest is dark data and bright data, respectively. There is a possibility that voltages of -Vap and -(1-27N)Vap are generated in either of the driving waveforms a and b for obtaining the state.

In FIG. 1Jg36, the drive waveform aVc is expressed as -Vap, and the drive waveform bK is expressed as -(1-2/N)Vap for convenience.

Regarding Figure @37, the voltage - to bring the pixel on the scan electrode of interest into a bright state at the previous scan timing.
(i-5/X) Vap and -(1-2/N)Vap
changes depending on the display data of the pixels on one scanning electrode.

In the drive waveform a in FIG. 36, after −Vap is applied, the voltages (1-4/N) Vap and (1-2/N) Vap
The molecules move so that a dark state is obtained.

On the other hand, in the drive waveform of Fig. 36, the voltage - (1-2/N)
Vap is applied, and the molecules move so that the display becomes bright, and then the voltage (-47N) Vap causes the molecules to move slightly to the position where the display becomes dark, but (1-4/N)
From the relationship Vap((1-2/N) Vap,
The molecule position is the voltage (1-2/N) Va of drive waveform a
A position is reached where the display state is closer to the gate state than the position dictated by p.

In this case, the voltage values of -Vap and -(1-27N)Vap must be set so that the molecule can move to a position where a sufficiently bright state is obtained.

(1-27N) Vap and (1-4/N) Va
After p is applied, an alternating current pulse with an amplitude of 1/NVap is applied to the liquid crystal to maintain the display state.

The driving waveforms a and b in FIG. 37 can be explained in the same way as the driving waveforms a and b in FIG. 36.

In the case of FIG. 37, at the timing when the scan electrode immediately before the scan electrode of interest in FIG. and -(1-2/N)Vap, and the difference between them is 2/NVap, compared to -(1-2/M)
Vap and -(1-3/N) Vap, and the difference is
1/NVap, and the difference is small.

In addition, in the case of drive waveform a in FIG. 37, voltage -(1-3/
The high positive voltage 3/NVap following N) Vap has a voltage-to-amplitude ratio of 3=1 with respect to the subsequent alternating current pulse of amplitude 1/NVap.

The changes in the amplitude of the AC pulse and the optical transmission intensity in Figure 8 are
In other words, the smaller the amplitude, the less the change in optical transmission intensity will be if the ratio between the initially applied DC voltage and the amplitude of the AC pulse is large.

The 36th drive waveform a is the voltage value of the high voltage pulse (1-2/N) Vap, and the amplitude of the AC pulse is 1/
While the ratio of NVap changes as N (which is called the bias number in voltage averaging and will be called the same in the present invention) increases, the 37th
In the case of drive waveform a in the figure, it is fixed.

In addition, the drive waveform in FIG. 37 is voltage - (1-2/N)
There is no high voltage after Vap is applied, and 1/NVap, which is equivalent to the amplitude of the AC pulse, is applied.

The order of superiority of the driving methods shown in FIGS. 36 and 37 varies depending on the characteristics of the liquid crystal, the number of biases N, etc.

Of course, it is also possible to set all the pixels on the scan electrode to a bright state at the timing when the nth scan electrode before the scan electrode of interest is scanned. (n can be up to the total number of scanning lines minus 1) However, if n is large, the bright time becomes longer and the dark state becomes flickering.

Next, the second line sequential drive will be explained.

FIG. 38 shows an example of driving waveforms a and b and a scanning signal C actually applied to the liquid crystal using this driving method.

This driving method uses a high voltage pulse to set the display state to either a bright or dark state during the first half of the time that the scan electrode is scanned, and then During the second half, a high voltage of opposite polarity to the high voltage pulse is applied to change the state from bright to dark or dark to bright, or a low voltage is applied to leave the state unchanged. This is a driving method in which the state is determined and then an AC pulse is applied to maintain the display state.

Of course, as in the first driving method, the direction of the voltage may be opposite to that shown in FIGS. 38a and 38b.

Drive waveforms a and b in FIG. 38 are examples in which the AC pulse is the highest voltage pulse.

In the case of FIG. 38, in the drive waveform a, the molecules move so that the display state becomes a dark state due to the high voltage %Vap, and then the display state is maintained by the alternating current pulse with the amplitude %Vap.

In the driving waveform, the molecules move so that the display state becomes dark due to the high voltage Vap, and the next voltage -%Vap
With this voltage, the molecules shift in the opposite direction and the display becomes bright. Thereafter, the display state is maintained by an AC pulse of amplitude QVap.

In the first driving method, all pixels on the scan electrode of interest are brought into a bright or dark state at the timing when the scan electrode immediately before the scan electrode of interest is scanned.
The second driving method uses a high voltage to create a bright or dark state during the first half of the scanning time, and then changes the display state by applying a high voltage of the opposite polarity during the second half of the scanning time. Decide.

In other words, in the first driving method, the display state is determined in two scanning times, whereas in the second driving method, the display state is determined in one scanning time.

φY, which is the basic signal to obtain the drive waveform shown in Figure 38.
, TI, φx, and 4rx are shown in FIG.

Selecting FIG. 39 using the scanning signal and display data,
FIG. 40 shows the voltage waveforms applied to the scanning electrodes and display electrodes.

The voltage waveform a in FIG. 40 is the voltage waveform applied to the scanning electrode. When the scanning signal is at H1gh level, the φY signal in FIG. 39 is selected, and when the scanning signal is at Low level, the φY signal in FIG. 'Jy signal.

Voltage waveform C in FIG. 40 is created by signal d, which is an example of display data. When the signal d is at the R1gh level, the sixth
When φX in Figure 9 is selected and the signal d is low level, the third
φX in FIG. 9 is selected, resulting in voltage waveform C, which is applied to the display electrodes.

FIG. 41 shows a general case of driving waveforms a and b in FIG. 40, which is an example of this driving method.

N is a number similar to the number of biases in the first driving method,
An AC pulse having an amplitude of VN of the voltage value Vap of the highest voltage pulse is added to maintain the display state.

The drive waveform a in FIG. 41 is 1. This is a general form of the drive waveform a in FIG. 40, which is a pulse of high voltage (1-2/N) Vap, and then an alternating current pulse with an amplitude of 1/N Vap is applied to the liquid crystal.

The drive waveform shown in FIG. 41 is a general form of the drive waveform shown in FIG. 40, in which a pulse of high voltage Vap is applied to the liquid crystal.
Thereafter, a voltage of -3/N Vap briefly changes the display, and then an alternating current pulse with an amplitude of 1/NVap is applied.

As described above, the two driving methods can write brightness and darkness in one scan, compared to the driving method described above in which brightness and darkness are written in the first scan and second scan.

This point is largely different from the first driving method.

SmO''k is driven by the drive waveform as described above.

Positive/negative V is applied to the pixel on the selected electrode among the scanning electrodes.
When ap is applied, the liquid crystal molecules move to a or a in FIG.
’ position, or close to that position, reaching the highest level of optical brightness and darkness.

The optical transmittance then oscillates and attenuates due to the applied alternating current pulses that oscillate equally in positive and negative directions, but the attenuation is greatest immediately after the equal positive and negative alternating current pulses are applied, and there is almost no change thereafter. do not have.

When the number of divisions is large, the time during which scanning electrodes are selected becomes short and the non-selection time occupies most of the time.

For example, if the number of divisions is n, -scanning time is t. Then, the time to select all one scanning electrode is 1. is tH” t6 /
It is represented by n.

Moreover, the time t, which is not selected is, (N　Ot.

It is.

The optical transmittance when an AC pulse is applied during non-selection oscillates as described above, but the magnitude hardly changes.

Since this state occupies most of the scanning time, the optical transmittance of this state is perceived by the human eye as the contrast of the pixel.

Therefore, whether the number of divisions is large or small, the contrast remains the same.

In our measurements, in a panel that is currently capable of driving 256 divisions, the contrast did not change much from 8 divisions to 256 divisions.

This phenomenon of ``SmO'' is extremely suitable for multi-segment display compared to the fact that as the number of divisions increases in a TN type liquid crystal display panel, there is no difference in effective voltage between selected points and non-selected points, resulting in a decrease in contrast. It's Haraeru.

If the response of "smo" is possible up to 10 μm, the number of divisions will be about 3000(μ.)n 1500 scratches.

1ox2 (μ5ec) However, 30 μsec is the time required for one scan.

Moreover, 2 in the denominator indicates that positive and negative voltages are taken during the selected time.

When the liquid crystal responds at the highest speed ever achieved in the world, it is possible to drive a panel with approximately 1500 divisions, and as mentioned above, the drive of the present invention ensures that there is no difference in contrast between 1500 divisions and 8 divisions. It is possible by law.

Here, another advantage of the present invention regarding contrast will be described.

When the cell gap is reduced to about 1 μm, SmO* loses its helical structure and the layers are aligned perpendicular to the panel substrate. This is as stated before, but when the layer is perpendicular to the substrate, it means that the liquid crystal molecules are horizontal to the substrate.

When the molecule in this state is driven by the driving method according to the present invention, it is in the state b' close to '4't' in FIG. 9, so it can be considered that the molecule is approximately parallel to the substrate.

Even when this state is viewed from various viewing angles, there is almost no change in contrast because the molecules are horizontal to the substrate.

This is because in a TN type liquid crystal display panel, when the liquid crystal is not lit (positive display), the liquid crystal is not completely horizontal to the substrate, and depending on the viewing angle, it may be considered to be standing, causing crosstalk.

This is known as so-called viewing angle dependence.

The display according to the present invention using SmO"f has no viewing angle dependence.Multi-segmentation completely changes conventional common sense, and like our friend,
Regarding contrast, it can be said that the display element using SmO*ffi according to the present invention has revolutionary characteristics such as no viewing angle dependence and no change in contrast depending on the number of divisions.

Further, FIG. 42 shows an example of the drive waveform according to the present invention.

This drive waveform is the drive waveform etc. of the above five methods.
This is the voltage change applied to the liquid crystal when the display is maintained in the high impedance pair state 1- after being scanned once or a limited number of times.

In FIG. 42, a indicates the scanning portion and b indicates the current impedance state.

It is clear that the optical transmittance remains almost unchanged even when the impedance is set to zero, which indicates that the high impedance state occurs at the positions s and b' in FIG.

This memory property is long enough, and only when the display changes
All you have to do is scan.

The power consumption in the high impedance state is zero, which is an energy-saving type of drive, and is most suitable for image display where the display contents do not change much, such as fixed foot display.

An example of a drive waveform similar to this drive is shown in FIG. 43.

Similar to the driving method using high impedance shown in FIG. 42, after scanning is performed once or a limited number of times, the driving frequency is increased to maintain the display.

In the drive shown in Fig. 42, which uses high impedance to rememory, the molecular position becomes no impedance and gradually returns to the initial orientation state from the point when the external regulating force disappears. The phenomenon of returning to the initial orientation state at high impedance is greater as the alignment force is stronger, and as the light temperature is higher, the phenomenon is greater.

Since the influence of temperature is particularly large, it is more reliable to maintain the display by increasing the drive frequency as shown in FIG.

In the case of the drive shown in FIG. 43, scanning can be carried out normally and only the drive frequency needs to be increased. Furthermore, on the display electrode side, display data may be output as is, or may be set to be lit or non-lit.

Next, an embodiment of a drive similar to that shown in FIG. 43 is shown in FIG. 44.

The difference from the drive shown in Fig. 43 described above is that after one or a finite number of scans, an AC pulse with the same positive and negative voltages applied during non-selection, or with different voltages, is applied. The point is that the display state is maintained by applying the voltage. In this case, the frequency is selected appropriately.

FIG. 44 shows a drive waveform to which an AC pulse of ±V3Val) is applied.

In the case of this embodiment, the driving waveforms applied to the scanning electrodes and the display electrodes after scanning are equal amplitude waveforms with different phases as shown in FIG. 45.

In this case, the scan electrodes are not scanned, and regardless of the display data, one of the waveforms shown in FIG. 45 is sent to the scan electrodes.
The other waveform is applied to the display electrode.

Next, an embodiment of the driving method according to the present invention for obtaining gradation display will be described.

The basic method for grayscale display is to create halftones by modulating the width of the ±Vap pulses applied to pixels on selected scanning electrodes.

Focusing on the change in optical transmittance during driving, the selection voltage ±
When Vap is added, the brightness and darkness reach the highest level. After that, it attenuates, but after a sufficient period of time has elapsed, the optical transmittance when the attenuation almost disappears is the selected voltage value Va.
It was observed that the optical transmittance is proportional to the magnitude of the optical transmittance when p is added.

Utilizing this phenomenon, gradation display is possible by adjusting the optical transmittance at the time of selection.

Since an optical transmittance proportional to the pulse width of the selection voltage ±Vap can be obtained, a gradation display can be realized by this method.

Examples of drive waveforms are shown in FIGS. 47 to 59.

Each will be explained below.

FIG. 47 is an example of the waveform attached with the suffix l in FIG. 12, that is, the waveform used for the previous run, which has been modified for gradation display.

The only difference between FIG. 47 and FIG. 12 is the segment selection signal; the other signals are the same.

In the embodiment, the selection voltage Vap is modulated by shifting the phase by τm.

The pulse width τap to which the selection voltage Tap is applied is 'rap=7'-rm, where f is the driving frequency. τm is adjusted according to the intermediate level to perform gradation.

FIG. 48 shows an example of the voltage actually applied to the liquid crystal from the signal shown in FIG. 47.

In Fig. 48, a shows the waveform applied to the liquid crystal when the scanning electrode is selected and a selection signal is applied to the display electrode, and b shows the waveform when the scanning electrode is not selected and a non-selection signal is applied to the display electrode. It is a waveform. Also, contrary to c ld b, this is a waveform when the scanning electrode is not selected and a selection signal is applied to the display electrode.

The time for taking % Vap for both b and a is taken into consideration so that it is equal in b and c.

Similarly to FIG. 47, FIG. 491 also shows a waveform obtained by modifying the signal for non-lighting scanning in FIG. 16 for gradation display. The difference from FIG. 47 is that the segment selection signal has a stepped waveform. Selection voltage applied to liquid crystal -Va
The pulse width of p is narrowed by τm, and gradation display is performed by adjusting it in accordance with the intermediate tone level τmf.

Note that, like FIG. 48, FIG. 50 shows the waveforms applied to the liquid crystal. In the figure, a, b, and c indicate the same states as in FIG. 48, and have waveforms with the polarities of the waveforms in FIG. 48 inverted.

FIGS. 51 to 53 show an example in which the drive waveform to which an AC pulse with an amplitude of 14 Vap is applied when not selected is changed for gradation display.

All that needs to be changed is the segment selection signal, similar to the above.

There are two patterns to change.

There are two cases: the case where the phase changes stepwise as shown in FIGS. 51 and 55, and the case where the phase changes as shown in FIG. 52.

Next, FIGS. 54 to 59 show an example in which the drive waveform is changed to display the full gradation of the amplitude of "A Vap" when not selected.
As shown in the figure.

Similar to the gradation display described above, there are two ways to change the waveform: a stepped waveform and a waveform with different phases.
Only Vap'Thrm can be modulated.

It was previously shown that there are generally two ways to modify the segment selection signal to obtain a gray scale display.

That is, (1) the phase is shifted, and (2) the step waveform is formed. An example of the step waveform of (2) is shown in FIG. 60 for the bifurcated case.

The top two are staircase waveforms when the lights are on, and the bottom two are when the lights are off.

vl, e, and vl are the following voltages, respectively.

(2)+=(' (2/a) Vapl V, = (2/a) Vap a is the number of assigned children, and an AC pulse of ±(1/a) Vap is applied when not selected.

In any of the above driving methods, temperature compensation is possible by frequency.

FIG. 61 shows all the changes in response time with temperature.

The response time decreases monotonically as temperature increases.

When the temperature rises and the response time becomes shorter, if the drive voltage or drive frequency remains the same as when it was at a low temperature, even the AC pulse voltage and pulse time width when not selected will provide a sufficient response.
Memory performance deteriorates.

This is perceived by the human eye as a flicker.

Temperature compensation can be achieved by adjusting the drive voltage and drive frequency so that sufficient display is achieved at low temperatures, and controlling the frequency as the temperature rises.

Of course, control by voltage is also possible.

Temperature compensation by voltage is changed by Vap f temperature.

As described above, the display element according to the present invention using SmO* is an epoch-making liquid crystal display element that overcomes the limitations of conventional XY matrix type liquid crystal display elements that do not use active elements. By using this element, a multi-segment display can be driven by a simple matrix, the number of driver ICs can be greatly reduced, and since it is a simple panel that does not use active elements, it is possible to realize an inexpensive large-capacity liquid crystal panel. .

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the molecular arrangement of N, SmA, and SmO. FIG. 2 is a schematic diagram of the molecular arrangement of chiral nematic. FIG. 3 is a diagram schematically showing the molecular arrangement around the helical axis of S+nO* and one state of a single molecule. Figure 4 shows that when the cell gap is reduced to about 1 μm,
FIG. 2 is a diagram showing how molecules are arranged on a substrate. FIG. 5 is a schematic diagram showing the molecular state and the conventional display principle as seen from the direction of the substrate. FIG. 6 shows the relationship between transmitted intensity and applied voltage when a voltage is applied from a bright state and a threshold characteristic is obtained. FIG. 7 shows the change in optical transmission intensity when an AC pulse voltage is applied immediately after applying a DC voltage. FIG. 8 shows the change in optical transmission intensity when the amplitude and frequency of the AC pulse in FIG. 7 are changed. FIG. 9 is a schematic diagram showing the molecular state in the display element according to the present invention. FIG. 10 shows one implementation of the driving waveform of the first driving method for driving the liquid crystal when the present invention is applied to time-division driving. FIG. 11 is a diagram showing the relationship between applied voltage and response time. Figures 12 to 17 show ± when selecting the first driving method.
An example of a basic signal for applying an AC pulse of ±1 Vap when Vap and non-selection is shown. Figure 18 shows Figures 12 to 17 in the first driving method.
φY, JY, φI using the basic signals shown in the figure. 'tx signal is shown. Figure 19 shows φy, $y, φx, ';l in Figure 18.
=x> indicates a signal selected from the scanning signal and display data and applied to the scanning electrode and the display electrode. FIG. 20 is a block diagram of a display device using the present invention, and FIG. 21 is an embodiment of a circuit diagram of a drive voltage generation circuit in the block diagram. Similarly, FIG. 22 is an embodiment of the circuit diagram of the display electrode driver circuit and the scan electrode driver circuit in the block diagram. FIG. 23 is a diagram showing a time chart of control signals for controlling the drive voltage generation and consolidation shown in FIG. 21. FIG. 24 shows ±1/1 when not selected in the first driving method.
It shows a driving waveform for driving the liquid crystal when an AC pulse called 'NVap is applied. FIGS. 25 to 30 are examples of basic signals of the first driving method designed to apply an AC pulse of ±1 A Vap when not selected. Figure 31 shows that all pixels on one scanning electrode are brought into a bright or dark state at a scanning timing immediately before the scanning timing, and then whether or not a high voltage of opposite polarity is applied to the intermediate and dark areas is determined. This is an example of a driving waveform and a scanning signal applied to a liquid crystal in a driving method that determines brightness and darkness. FIG. 52 shows the change in optical transmittance when the liquid crystal is driven with the drive waveform shown in FIG. 31. FIGS. 33 and 34 are examples of basic signals that realize the drive waveform shown in FIG. 32. FIG. 35 shows an example of the voltage and pressure waveforms actually applied to the scanning electrodes and the display electrodes according to the scanning signal and display data. FIGS. 36 and 37 are examples of driving waveforms in a general case where an AC pulse of ±1/NVap is applied to the liquid crystal when not selected. FIG. 38 shows that all the pixels on the scanning electrode being scanned are brought into a bright or dark state for an arbitrary period of time during scanning, and then a high voltage of opposite polarity is applied during the subsequent scanning period; This figure shows an example of a driving waveform and a scanning signal applied to a liquid crystal in a driving method in which the bright/dark state is completely determined depending on whether the liquid crystal is turned on or off. FIG. 39 shows an example of a basic signal that realizes the drive waveform shown in FIG. 38. FIG. 40 shows an example of voltage waveforms applied to the scan electrode and display electrode when the basic signal of FIG. 39 is selected based on the scan signal and display data. FIG. 41 is an example of the general form of the drive waveform of FIG. 39. Figures 4 and 2-44 are examples of the voltage applied to the liquid crystal when using a driving method of 70-ting and increasing the frequency and applying a complete AC pulse after a finite number of scans. FIG. 45 shows the waveforms applied to the common and segment electrodes after the finite number of scans of FIG. 44. FIG. 46 shows an example of the voltage applied to the liquid crystal when a driving method with a finite number of scans and zero volts is used. Figures 47 to 53 show gradation by modulating the selection voltage Vap, and Figures 47 to 59 show the positive and negative alternating current pulses of %Vap when not selected. This is an example of a basic signal that is applied and modulates the selection voltage Vap to display gradation. FIG. 60 shows the changing pattern of the segment selection signal for gradation display. FIG. 61 is a diagram showing the relationship between response time and temperature of a ferroelectric liquid crystal. That's all Figure 4 Figure 5 Q Figure 5 Figure 7 Figure 8 Vth Vsat V 5 angle ::, the limit is also −−−−−−−−.

Claims (9)

[Claims] (1) A cell in which a ferroelectric liquid crystal is sandwiched between two light-transmissive substrates with electrodes formed on their surfaces, which are placed parallel to each other and facing each other, is placed between two upper and lower polarizing plates. Using a liquid crystal display element with the same configuration, we can measure the change in optical anisotropy caused by the change in the molecular arrangement of the ferroelectric liquid crystal held between the electrodes when a voltage is applied between the opposing electrodes.
In a liquid crystal display device that displays changes in the amount of light transmitted through two polarizing plates, a DC voltage is applied to change the molecular arrangement described above, and an AC voltage is applied to keep the molecular arrangement unchanged. A liquid crystal display device in which ferroelectric liquid crystal molecules in pixels whose display state is maintained constant perform display in an array state that is not parallel to the electrode surface. (2) In the liquid crystal display device according to claim 1, when applying a voltage between the electrodes facing each other in parallel, first the DC voltage +Vap or -Vap with a desired time width is applied. Therefore, by changing one of the two alignment states of ferroelectric liquid crystal molecules representing a lit or non-lit state from one to the other, and by applying an alternating current voltage whose effective voltage is smaller than the absolute value of the voltage ±Vap. , a liquid crystal display device that is driven so as not to change the arrangement state of ferroelectric liquid crystal molecules representing a previously selected lighting or non-lighting state. (3) In the liquid crystal display device according to claim 2, the ferroelectric liquid crystal molecules have two alignment states that indicate lighting or non-lighting depending on a DC voltage having a desired time width, +Vap or -Vap. a first selection voltage having a polarity that selects either the lighting or non-lighting molecular arrangement state when changing from one to the other;
a first scan by +Vap (or -Vap); a second selection voltage having a polarity opposite to that of the first selection voltage;
A liquid crystal display device driven by alternately performing a second scan in which −Vap (or +Vap) is applied and the other molecular alignment state is selected. (4) In the liquid crystal display device according to claim 2, two of the ferroelectric liquid crystal molecules are turned on or off in response to a DC voltage of a desired time width, +Vap or -Vap. When selecting one array state,
+Va, a voltage that selects the arrangement state of ferroelectric liquid crystal molecules that indicates either lighting or non-lighting for all pixel electrodes on the scanning electrodes N lines ahead of the selected scanning line;
After applying p (or -Vap) uniformly, the molecular arrangement state of each pixel is determined by selectively scanning the pixels by applying a voltage of opposite polarity to the voltage, -Vap (or +Vap). A liquid crystal display device that is driven as specified. (5) In the liquid crystal display device according to claim 2, two of the ferroelectric liquid crystal molecules are turned on or off depending on a DC voltage of a desired time width, +Vap or -Vap. When selecting one array state,
The scanning time of one scanning electrode is divided into two time widths, the front and back, and the voltage +Vap (or -Vap), and then in the second half, a selection voltage of opposite polarity to the first half, -Vap
A liquid crystal display device that is driven by selectively applying (or +Vap) to each pixel to determine the molecular alignment state of each pixel on a scanning electrode. (6) An arrangement of ferroelectric liquid crystal molecules that indicates lighting or non-lighting for each pixel by the method according to any one of claims 2, 3, 4, and 5 above. After a finite number of selective voltage scans that define the state, the voltage applied to the electrodes is floated or the driving frequency is increased. Alternatively, by applying alternating current pulses having equal positive and negative peak values, the arrangement state of the ferroelectric liquid crystal molecules for each pixel as defined above is maintained and display is continued, according to claim 1. LCD display device. (7) In the case of applying a selection voltage that defines a display state to each pixel in the claims 1, 2, 3, 4, 5, and 6 above, , a liquid crystal display device that performs gradation display by modulating the time width of the selection voltage. (8) Claims 2, 3, and 4 in which temperature compensation is performed by changing the selection voltages +Vap and -Vap;
The liquid crystal display device described in Items 5, 6, and 7. (9) A liquid crystal display device according to claims 2, 3, 4, 5, 6, and 7, in which temperature compensation is performed by changing the driving frequency.