JPH02918A - Optical modulating element - Google Patents

Abstract

PURPOSE:To facilitate initial orientation and eliminate the need for an extremely thin film, to make the oriented state of a liquid crystal material hard to destroy, and to obtain gradations by providing a liquid crystal element made of the liquid crystal material which has a smectic A phase. CONSTITUTION:The liquid crystal material 5 which has the smectic A phase is filled in the liquid crystal cell formed of two opposite transparent substrates 2 having electrodes 3 to form a liquid crystal element, which is arranged between two polarizing plates 1 whose directions of polarization are orthogonal or parallel to each other. The temperature of the optical modulating element of this constitution is varied to hold the liquid crystal material 5 in the smectic A-phase state and an electric field is applied to vary the orientation direction of the molecule major axis of the liquid crystal material 5 and then vary the transmissivity of light, thereby performing the optical modulation. Consequently, this optical modulating element is oriented easily and initially and no extremely thin film is required; and resistance to a mechanical shock is obtained in the oriented state and excellent gradations are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a light modulation element using a liquid crystal exhibiting a smectic A phase, and more specifically to a method for applying an electric or magnetic field to a liquid crystal material containing a liquid crystal exhibiting a smectic A phase. The present invention relates to an element that adjusts the amount of light transmitted through the device.

Technical background of the invention and its problems Various proposals have been made for light modulation elements using ferroelectric liquid crystals.

To drive such a light modulation element, a thin film of ferroelectric liquid crystal is placed between two polarizing plates whose polarization directions are orthogonal, and the birefringence of the ferroelectric liquid crystal is used to modulate the transmitted light. There are known methods to do this (Abride Physics Letters (AppPhys, Lett), Volume 36,
(See page 899, (i980)).

The ferroelectric liquid crystal has a layered structure in the xylsmectic C phase, and within this layer, the long axes of molecules are oriented to form a substantially constant angle (referred to as tilt angle) θ. As the transmitted light travels through the liquid crystal, a helical structure is formed in which the long sleeve direction of the liquid crystal material gradually changes direction (Fig. 1).

When a ferroelectric liquid crystal material is filled into a liquid crystal cell with a gap of about 2 microns, the ferroelectric liquid crystal material is influenced by the substrate and is oriented parallel to the substrate, so there are only two types of orientation directions. (Figure 2).

When an electric field is applied to the liquid crystal material oriented in this manner, the long axes of the molecules become oriented in one direction due to the interaction between the spontaneous polarization of the liquid crystal material and the electric field (FIG. 3a). moreover,
When an electric field is applied in the opposite direction to the liquid crystal material oriented in the -force direction, the liquid crystal material becomes oriented in a stable direction different from the above direction (FIG. 3b).

A light modulation element can be formed by combining the liquid crystal material oriented in this manner and a polarizing plate. That is, if the angle θ formed by the molecular alignment direction of the liquid crystal material and the polarization axis direction of the polarizing plate is zero, the amount of light transmitted through the element will be minimum, and when θ is 45 degrees, the transmitted view will be maximum. Therefore, by arranging the polarizing plate so that the molecular orientation direction and the polarization direction form an appropriate angle, light can be modulated.

Compared to conventional liquid crystal devices, light modulation devices that utilize the birefringence of ferroelectric liquid crystals have the following advantages: (1) low power consumption, (2) high-speed response, (3) ability to maintain memory states, (
4) Since it has advantages such as having a steep and low threshold voltage, it is considered to be particularly promising as a light modulation element, especially a display device.

However, such a light modulation element has not been put into practical use at present.

This is because ■ it is difficult to create thin film elements with uniform thickness;
This is due to the following reasons: 1) It is difficult to reproducibly control a uniform alignment state, 2) The alignment state of the liquid crystal material is susceptible to mechanical shock, and 2) It is difficult to display gradations.

Furthermore, regarding memory properties, which are considered to be an advantage of such devices, it is extremely difficult to achieve two memory states equally through interactions between molecules and interfaces alone.

In addition, a so-called guest-host type light modulation device has been proposed, which mixes ferroelectric liquid crystal and dichroic dye and modulates light by utilizing the light absorption of the dye (
For example, see "High-speed Liquid Crystal Technology" by Katsumi Yoshino, published by CMC Publishing, 1986).

This element modulates light by utilizing the effect that when the liquid crystal substance changes its alignment direction in response to an electric field, the dye also changes its direction accordingly (Figure 4). By utilizing chromaticity, the amount of transmitted light can be controlled with a single polarizing plate.

However, in this case as well, it is basically necessary that the initial orientation of the liquid crystal material be good, similar to the method using birefringence. Therefore, orientation control similar to the method using birefringence is difficult. Furthermore, since dyes are used, the element must have a certain thickness (several microns) to obtain sufficient contrast.
It is necessary to have the following. For this reason, orientation control using the orientation force of the substrate surface becomes increasingly difficult. In addition, since this method generally performs display using the xylsmectic C phase, it is difficult to (1) align the liquid crystal material uniformly and with good reproducibility, and (2) it is difficult to align the liquid crystal material uniformly and with good reproducibility. It has problems such as being easily destroyed by impact and difficulty in displaying gradations.

By the way, liquid crystals change from solid state to solid state as the temperature changes.
Phase changes between liquid crystal state and liquid state. It is well known in literature that many phase states exist even within a liquid crystal phase (for example, see "Latest Technology of Liquid Crystals", co-authored by Tadashi Matsumoto and Seiji Tsunoda, published by Kogyo Chosenkai, 1983).

When using a ferroelectric liquid crystal as a light modulation element, for example, the ferroelectric liquid crystal is interposed between two opposing transparent substrates with electrodes, and placed between two mutually orthogonal polarizing plates. The temperature is changed to maintain the ferroelectric liquid crystal in the xylsmectic C phase state. By applying an electric field to this, the orientation direction of the long axes of the molecules changes, making it possible to perform optical modulation.

When using a ferroelectric liquid crystal as a light modulation element in this manner, it is necessary to bring the ferroelectric liquid crystal into a good alignment state at an early stage. That is, how to improve the initial alignment state of the liquid crystal material is a key factor in obtaining a characteristically excellent light modulation element. Methods for initial alignment of ferroelectric liquid crystal include temperature gradient method and surface treatment θ.

(For example, see "High-speed Liquid Crystal Technology" by Katsumi Yoshino, published by CMC Publishing, 1986).

Here, the temperature gradient method is a method in which the temperature around the liquid crystal material is gradually lowered and the liquid crystal material is epitaxially grown from the spacer edge.

Further, the surface alignment method is a method of regulating the alignment direction of liquid crystal molecules using an alignment control film attached to the surface of a substrate or a substrate by a method such as coating or vapor deposition.

In order to orient a liquid crystal substance in this manner, a route is often taken in which the liquid crystal composition is once heated to a high temperature to be in a liquid state, and then the temperature is lowered.

When a liquid crystal substance is oriented in this way by cooling down from a liquid state, among the various liquid crystal phases, the xylsmectic C phase may appear immediately from the liquid state, but in many cases,
After passing through other liquid crystal phases, a xylsmectic 0 layer appears.

Specifically, from the high temperature side to the low temperature side, the liquid state → chiral nematic phase → smectic A phase → chiral smectic C phase liquid state -
Chiral nematic phase - Each phase appears according to thermodynamic stability in the following manner: xyl smectic C phase liquid state -> smectic A phase -> xyl smectic C phase.

Then, by applying an electric field or the like to this liquid crystal material in a temperature range in which the ferroelectric liquid crystal material shows the xylsmectic C phase, the orientation direction of the long axis of the molecules of this ferroelectric liquid crystal material changes. Ferroelectric materials can be used in light modulating elements.

For example, the compound DOBAMBCOC represented by the following formula
It has been reported that 113 exhibits a xylsmectic C phase in the temperature range of 63 to 92°C, and that the orientation direction of the long axis of the molecule can be changed by an electric field or the like within this temperature range (R, B, Meyer et at Journal de Phys., Volume 36, Page L69, (
(1975)).

However, as described above, it is very difficult to control the initial orientation in the xylsmectic C phase and maintain the orientation state, which is currently the biggest problem for practical use.

Purpose of the Invention The present invention attempts to solve the problems associated with the prior art as described above. It is an object of the present invention to provide a light modulation element having excellent features such as: (1) the alignment state of a liquid crystal substance is not easily destroyed by mechanical shock; and (2) it can have gradation.

Summary of the Invention A first light modulation element of the present invention includes two transparent substrates each having a transparent electrode provided on one surface, arranged so that the transparent electrodes face each other and a gap is formed by the substrates. The liquid crystal cell is characterized by having a liquid crystal element comprising a liquid crystal cell made of a liquid crystal cell and a liquid crystal substance exhibiting a smectic A phase filled in the gap.

A second light modulation element of the present invention is formed by arranging two transparent substrates each having a transparent electrode on one surface such that the transparent electrodes face each other and a gap is formed by the substrates. It is characterized by comprising a liquid crystal cell, a liquid crystal element comprising a liquid crystal substance exhibiting a smectic A phase filled in the gap, and a polarizing plate disposed on the outside of at least one of the transparent substrates.

A third light modulation element of the present invention includes two liquid crystal elements arranged between polarizing plates arranged such that the polarization directions are perpendicular to each other or parallel to each other, and the liquid crystal element has one surface that is transparent. Two transparent substrates provided with electrodes are arranged so that the transparent electrodes face each other and a gap is formed by the substrates, and a smectic A phase is applied to the gap of a liquid crystal cell whose peripheral edges are sealed. It is characterized in that the retardation value of light transmitted through the two liquid crystal elements is in the range of 0.13 to 0.26 μIYI.

The fourth light modulation element of the present invention includes a layer that reflects at least light in the visible region, a liquid crystal element, and a polarizing plate, and the liquid crystal element reflects light in the visible region even if it does not receive the visible light.

The liquid crystal element is arranged between a layer that reflects light and a polarizing plate, and the liquid crystal element has two transparent substrates each having a transparent electrode on one surface, the transparent electrodes facing each other, and It is characterized by comprising a liquid crystal cell arranged so that a gap is formed between the substrates, and a liquid crystal material exhibiting a smectic A phase filled in the gap.

A fifth light modulation element of the present invention is formed by arranging two transparent substrates each having a transparent electrode on one surface such that the transparent electrodes face each other and a gap is formed by the substrates. It has a liquid crystal element consisting of a liquid crystal cell and a liquid crystal material exhibiting smectic A phase filled in the gap, and the liquid crystal material is The width of the liquid crystal material is adjusted to a value that allows the liquid crystal material to be oriented, and the liquid crystal material is characterized by containing fibers having the characteristics expressed by the following formula.

Ω 3 ≦ ≦ 100 However, in the above formula, d represents the diameter of the fiber, and ρ represents the average length of the fiber.

A sixth light modulation element of the present invention comprises two transparent substrates each having a transparent electrode and an alignment control layer laminated in this order on one surface, the alignment control layers facing each other, and a gap formed by the substrates. It has a liquid crystal cell arranged so as to form a liquid crystal cell, a liquid crystal material exhibiting a smectic A phase filled in the gap, and a liquid crystal element whose periphery is sealed with the substrate, and the alignment control layer. is β above the curing temperature of the sealing member.
It is characterized by being formed of an organic polymer film having a dispersion temperature.

A seventh light modulation element of the present invention is characterized in that two transparent substrates each having a transparent electrode on one surface are arranged with a spacer in between so that the transparent electrodes face each other and a gap is formed by the substrates. a liquid crystal element consisting of a liquid crystal cell arranged in the liquid crystal cell and a liquid crystal substance exhibiting a smectic A phase filled in the gap,
A monodomain is formed by the interfacial effect between the spacer and the liquid crystal material, and the spacer is formed of a polyimide-based organic polymer material obtained by patterning a photosensitive polyimide precursor.

In the eighth light modulation element of the present invention, a liquid crystal element is arranged between polarizing plates arranged such that their polarization axes are perpendicular to each other or parallel to each other, and the liquid crystal element has a transparent electrode on one side. Two transparent substrates are arranged so that the transparent electrodes face each other and a gap is formed by the substrates, and a liquid crystal cell is sealed at the periphery, and a smectic A phase is filled in the gap. A liquid crystal substance that shows
Moreover, it is characterized in that a ferroelectric layer is provided on the transparent electrode so as to be in contact with the liquid crystal material.

A ninth light modulation element of the present invention is formed by arranging two transparent substrates each having a transparent electrode on one surface such that the transparent electrodes face each other and a gap is formed by the substrates. It has a liquid crystal cell and a liquid crystal element made of a liquid crystal material exhibiting a smectic A phase filled in the gap, and the liquid crystal cell has at least one liquid crystal element that maintains the gap and orients the liquid crystal.
It is characterized by the arrangement of two concentric spacer/orientation control layers.

A tenth light modulation element of the present invention is formed by arranging two transparent substrates each having a transparent electrode on one surface such that the transparent electrodes face each other and a gap is formed by the substrates. It has a liquid crystal element consisting of a liquid crystal cell and a liquid crystal material exhibiting smectic A phase filled in the gap, and the liquid crystal cell has a comb-shaped spacer and alignment controller that maintains the gap and orients the liquid crystal. It is characterized by the arrangement of layers.

An eleventh light modulation element of the present invention is formed by arranging two transparent substrates each having a transparent electrode on one surface such that the transparent electrodes face each other and a gap is formed by the substrates. It has a liquid crystal element consisting of a liquid crystal cell and a liquid crystal substance exhibiting a smectic A phase filled in the gap, and at least one transparent substrate constituting the liquid crystal cell is made of a flexible transparent substrate. There is.

A twelfth light modulation element of the present invention is formed by arranging two transparent substrates each having a transparent electrode on one surface such that the transparent electrodes face each other and a gap is formed by the substrates. It has a liquid crystal cell and a liquid crystal element made of a liquid crystal material exhibiting a smectic A phase filled in the gap, and at least one transparent substrate constituting the liquid crystal cell is made of a flexible transparent substrate, and the flexible The thickness t (mm) of the transparent substrate, the elastic modulus E (Kgf/m2), and the gap width a (mm) have the following relationship.

<0.32 t3 The thirteenth light modulation element of the present invention comprises two transparent substrates each having transparent electrodes on one side that have been subjected to alignment treatment, the transparent electrodes facing each other, and a gap formed by the substrates. The liquid crystal element includes a liquid crystal cell arranged to form a smectic A phase, and a liquid crystal material exhibiting a smectic A phase filled in the gap. It is characterized in that initial orientation is achieved by maintaining the temperature near the upper limit indicating the A phase and applying a DC bias voltage to the liquid crystal cell.

The fourteenth light modulation element of the present invention comprises two transparent substrates each having a transparent electrode on one surface, such that the transparent electrodes face each other and a gap of 1 to 3 μm in width is formed between the substrates. and a liquid crystal material exhibiting a smectic A phase filled in the gap. It is characterized by being formed by a spacer having a plurality of notches.

A fifteenth light modulation element of the present invention comprises two transparent substrates each having a transparent electrode provided on one surface, such that the transparent electrodes face each other and a gap of 1 to 3 μm in width is formed between the substrates. It has a liquid crystal element consisting of a liquid crystal cell disposed in the liquid crystal cell and a liquid crystal material exhibiting a smectic A phase filled in the gap, and at least one of the transparent substrates constituting the liquid crystal cell. It is characterized by the arrangement of nonlinear elements.

The 16th light modulation element of the present invention comprises two transparent substrates each having a transparent electrode on one surface, such that the transparent electrodes face each other and a gap of 1 to 3 μm in width is formed between the substrates. It has a liquid crystal element consisting of a liquid crystal cell disposed in the liquid crystal cell and a liquid crystal material exhibiting a smectic A phase filled in the gap, and at least one of the transparent substrates constituting the liquid crystal cell. It is characterized by the arrangement of active elements.

A seventeenth light modulation element of the present invention is formed by arranging two transparent substrates each having a transparent electrode provided on one surface such that the transparent electrodes face each other and a gap is formed by the substrates. It has a liquid crystal element consisting of a liquid crystal cell and a liquid crystal substance exhibiting a smectic A phase filled in the gap, and an organic thin film that orients the liquid crystal substance is formed on the surface of at least one of the transparent electrodes. It is characterized by

The 18th light modulation element of the present invention is formed by arranging two transparent substrates each having a transparent electrode on one surface such that the transparent electrodes face each other and a gap is formed by the substrates. It has a liquid crystal element consisting of a liquid crystal cell and a liquid crystal substance exhibiting a smectic A phase filled in the gap, and an inorganic thin film capable of orienting the liquid crystal substance is formed on the surface of at least one of the transparent electrodes. It is characterized by

The light modulation element of the present invention has excellent characteristics such as: (1) initial alignment can be easily performed, (2) no ultra-thin film is required, (2) the alignment state is resistant to mechanical shock, and (2) it can have gradation. have.

Detailed description of the invention Next, the light modulation element of the present invention will be specifically explained.

The light modulation element of the present invention basically comprises two transparent substrates each having a transparent electrode on one surface, a liquid crystal cell having a gap formed by these two transparent substrates, and a gap between the liquid crystal cells. It has a liquid crystal material exhibiting a smectic A phase filled with the liquid crystal material. The transparent substrate described above is arranged so that the transparent electrodes provided on the surface thereof face each other, and has a gap that is filled with a liquid crystal material. That is, the light modulation element of the present invention basically has a structure as shown in FIG. However, FIG. 7 shows an embodiment in which a liquid crystal element is disposed between two polarizing plates.

In the present invention, as the transparent substrate, for example, glass, a transparent polymer plate, etc. can be used.

Note that when a glass substrate is used, an undercoat layer containing, for example, silicon oxide as a main component may be provided on the surface of the glass substrate in order to prevent deterioration of the liquid crystal material eluted with the alkali component.

For example, in the case of a glass substrate, the thickness of the transparent substrate is usually within the range of 0.01 to 1.0 mm.

Further, in the present invention, a flexible transparent substrate can also be used as the transparent substrate. In case 2, one of the two transparent substrates may be a flexible transparent substrate,
Furthermore, both may be flexible substrates.

When using a flexible transparent substrate in this way, the thickness t (n++*) of the flexible transparent substrate and the elastic modulus E (kgf'/go)
and the width a of the gap formed by such a flexible substrate
(mm) preferably has a relationship expressed by the following formula.

32 t3 As such a flexible transparent substrate, a polymer film or the like can be used.

A transparent electrode is provided on at least one surface of such a transparent substrate.

The transparent electrode is formed by coating the surface of the transparent substrate with, for example, indium oxide, tin (ITO), or the like. The transparent electrode can be formed by a known method.

The thickness of the transparent electrode is typically in the range of 100-2000.

A transparent substrate provided with such a transparent electrode may further include an alignment control layer or a ferroelectric layer on the transparent electrode. For example, the alignment control layer aligns the liquid crystal material,
It may be an organic or inorganic thin film that can be coated.

Examples of organic thin films include polymer thin films such as polyethylene, polypropylene, polyester, nylon, poval, and polyimide. Examples of the thin film forming method include a coating method, an adhesion method, and a polymerization method on a substrate (plasma polymerization). Furthermore, an organic thin film can be formed by chemically adsorbing an organic silane coupling agent or a carboxylic acid polynuclear complex.

Examples of inorganic thin films include silicon oxide, germanium oxide,
Examples include oxide thin films such as alumina, nitrides such as silicon nitride, and other semiconductors. Examples of thin film forming methods include vapor deposition, sputtering, and the like.

As a method for imparting liquid crystal orientation to such a thin film,
There are methods of imparting anisotropy or shape specificity to the thin film itself during film formation, and methods of imparting properties from the outside after forming the thin film. Specifically, methods include a method using a stretched film of a polymer compound, a method of obliquely depositing silicon oxide, and a method of rubbing the surface of a polyimide film in one direction.

Further, as shown in FIG. 16, such a transparent electrode 16
A ferroelectric layer 167 may be provided on the ferroelectric layer 5 .

Note that the orientation control layer and the like may be formed so as to also serve as a spacer, which will be described later.

Two transparent substrates as described above are arranged so that the transparent electrodes face each other and the transparent substrates form a gap to be filled with a liquid crystal material.

The width of the gap formed as described above is 1 to 10 μm.
1 Preferably 1 to 5 μm 1 More preferably 1 to 3 μm
It is desirable to do so. Such a gap can be easily formed, for example, by arranging two substrates so as to sandwich a spacer therebetween.

As such a spacer, for example, a polyimide polymer material obtained by patterning a photosensitive polyimide precursor can be used. .

By using such a spacer, a monodomain is formed due to the interface effect between the spacer and the liquid crystal material. Further, for example, as shown in FIGS. 17 and 18, the alignment control film and the spacer can be integrated by using a concentric spacer 176 or a comb-shaped spacer 186 that acts as an alignment control film. . Furthermore, a spacer with multiple notches can be used so that the liquid crystal material can be filled at the same time.

Further, as shown in FIG. 14, in addition to the above-mentioned spacers, fibers 47 are blended into the liquid crystal material 143.
The fibers also allow the transparent substrate 142 to form a constant gap.

In the present invention, it is preferable to use fibers whose average diameter and average length have the relationship expressed by the following equation.

3≦≦100 In the above formula, d represents the diameter of the fiber, and ρ represents the average length of the fiber.

Examples of fibers that can be used in the present invention include fibers obtained by spinning alkali glass.

By using such a fiber, the width of the gap formed by the transparent substrate can be controlled and maintained uniformly and uniformly.

Furthermore, granules may be blended instead of or together with the fibers.

Such granules are made of melamine resin, urea resin, benzoguanamine resin, etc. and have a particle diameter of 1 to 1.
Particulate matter of 0 μm may be mentioned. In addition, when using fibers or granules in this way, they can be premixed in a liquid crystal material or dispersed in a low boiling point solvent such as Freon. It can also be sprayed onto the substrate.

Furthermore, the above-mentioned fibers or granules can also be blended into the adhesive used to bond two transparent substrates together.

The two transparent substrates arranged so as to form a gap as described above are bonded together. Such adhesives include
Epoxy resins, silicone resins, and the like can be used. Furthermore, the epoxy resin or the like may be modified with an acrylic material, silicone rubber, or the like.

Further, normally, in order to close the notches for filling the liquid crystal material, after filling the gaps with the liquid crystal material, the portions where the notches and the like are formed are sealed with a sealing material.

Particularly in the present invention, it is preferable to perform sealing using a resin that cures at a curing temperature lower than the β-dispersion temperature of the polymer film used in forming the orientation control layer. Therefore, in this case, the orientation control layer is an organic polymer film having a β dispersion temperature higher than the curing temperature of the sealing material.

The gap in the liquid crystal cell having the above structure is filled with a liquid crystal material.

The liquid crystal material used in the present invention is Smectic A
It is a liquid crystal material that exhibits phases.

That is, a liquid crystal substance exhibiting a smectic A phase forms a layered structure, and its long molecular axis is parallel to the layer normal direction.

When a liquid crystal substance exhibiting an oriented smectic A phase is observed using a polarizing microscope, the streaky fan-like structure, abuse-like structure, marble structure, and schlieren structure that are observed in the xyl smectic C phase are not observed, and the short rod-like structure and simple structure are observed. Structures unique to smectic A phase, such as fan-shaped structures and simple polygonal structures, are observed.

The smectic A phase has a phase structure in which the long axis of the molecules is parallel to the layer normal direction, and when an external field such as an electric field is applied, the dipoles of the molecules align due to free rotation around the long axis of the molecules. Since the molecular long axis direction and the dipole direction are uniformly soloed (Fig. 5), the energy of the entire system (,I'!) increases and becomes unstable. Therefore, the potential energy is reduced. As a result, the long axis of the molecule stabilizes at a position tilted with respect to the normal direction of the layer (Figure 6).In other words, the tilt fθ induced by an external field such as an electric field ' is a constant stable angle other than 0 degrees.

Already in 1977, S. Garofr et al. (Physical Review Letters)
etters, ) Vol. 38, p. 848 (1977))
reported by.

A liquid crystal element formed by filling a liquid crystal material exhibiting such a smectic A phase into a liquid crystal cell formed by two opposing transparent substrates with electrodes has polarization directions that are perpendicular to each other or parallel to each other. It is placed between two polarizing plates. Then, by changing the temperature of the light modulation element having such a configuration to maintain the liquid crystal material in a smectic A phase state and applying an electric field, the orientation direction of the long axis of the molecules of the liquid crystal material changes, resulting in light transmission. Because the gender changes,
Light modulation can be performed.

Examples of liquid crystal substances exhibiting a smectic A phase that can be used in the light modulator of the present invention include compounds whose basic skeleton is represented by the following formula (I). Here, R is an alkyl group, an alkoxy group, or a haloalkyl group, Ω is 1 or 2, m is 1 or 2, n is 0 or 1, and A* is an optically active center. A group represented by the following formula (n) having (where xSy, z are,
is an atom or group selected from the group consisting of a halogen atom, a hydrogen atom, and an alkyl group, W is an alkylene group, and p is 0 or 1).

Among liquid crystal substances exhibiting a smectic A phase represented by the above formula (1), in the above formula (I), R has a carbon number of 2
is an alkyl group of 0 or less, m is 1, n is 1, and p
-o, and compounds in which x and ySz are mutually different atoms or groups are particularly preferred.

Further, as a preferable example of the group having an optically active center represented by the above formula (n), a group having an optically active center at a position close to PhPh-COO-Ph-COO- is particularly preferable.

Furthermore, examples of preferred liquid crystal substances that can be used in the present invention are shown below.

HH0 In the present invention, liquid crystal compounds exhibiting smectic A phase can be used alone or in combination.

Such smectic A filled in the gaps of liquid crystal cells
A liquid crystal material exhibiting a phase can be oriented using a simple alignment control method such as a temperature gradient method using a spacer edge or a surface treatment method using an alignment control film. Particularly in the present invention, it is preferable to maintain the liquid crystal cell at a temperature close to the upper limit of the smectic A phase of the liquid crystal material and to perform the initial orientation of the liquid crystal material by applying an electric field using a DC bias voltage.

The liquid crystal cell filled with the liquid crystal material and initially oriented in this manner is usually placed between two polarizing plates. These two polarizing plates are arranged so that their polarization directions are perpendicular to each other or parallel to each other.

As such a polarizing plate, for example, a polarizing film in which a resin film such as a polyvinyl alcohol resin film or a polyvinyl butyral resin film is stretched in the presence of iodine or the like to absorb iodine into the film and impart polarizing properties to the film is used. be able to. Such a polarizing film can also have a multilayer structure by coating the surface with other resins.

FIG. 7 shows an example of a light modulation element in which two polarizing plates as described above are arranged. In FIG. 7, 1 is a polarizing plate whose polarization directions are orthogonal to each other, 2 is a transparent substrate, 3 is a transparent electrode, 4 is a spacer that controls the thickness of the element,
5 is a liquid crystal material having a smectic A phase.

In addition, as shown in FIG. 13, a polarizing plate 131 as described above
a reflective layer 13 that reflects at least visible light;
It can also be set to 7.

Furthermore, as shown in FIG. 12, two polarizing plates 12
It is also possible to arrange two liquid crystal elements 128 between the two liquid crystal elements 128 so that the redardation value of transmitted light falls within the range of 0.13 to 0.26 μm.

In a general ferroelectric liquid crystal, when homogeneous alignment is performed, the induced tilt angle θ- is almost zero even if an electric field is applied in the temperature range of the smectic A phase. However, the above MHPOBC (4-(1-ietyl
heptyloxy carbonyl) phenyl
-4-octyloxy biphenyl-4-ca
When filled with compounds such as rboxylate),
The value of θ' is in degrees, and the value of θ' is within a sufficient range for a liquid crystal material used in a light modulation element.

Therefore, by using the above-mentioned compound, homogeneously aligning it, and applying an electric field between mutually orthogonal polarizing plates in the temperature range of the smectic A phase,
Light can be modulated.

By applying a voltage to such a light modulation element, the amount of transmitted light changes. For example, FIG. 8 shows an example of a change in the amount of transmitted light of a light modulation element using MHPOBC. In this example, the analyzer is arranged so that when the electric field becomes negative and the direction of the long axis of the molecule changes, the orientation direction matches the direction of the analyzer. Therefore, when the electric field becomes negative, the transmitted light intensity is at its minimum. The orientation direction of molecules within the device at this time is also shown. It can be seen from FIG. 8 that the light modulation is effectively performed. It can also be seen that gradation can be easily obtained from the relationship between the electric field strength and the amount of transmitted light.

When driving the light modulation element with an electric field, a nonlinear element or an active element can be used as an element for driving each picture element, for example, as shown in No. 11(a). Here, a nonlinear element is an element in which a change in applied voltage is not directly proportional to a resulting change in current, and an active element is an element that generates a voltage or current under an impedance network.

More specifically, as a two-terminal nonlinear element, a varistor MIM (Metal In5ulator) is used.
It is possible to utilize the nonlinearity of a resistor such as a diode (Metal) or a diode.

In addition, active elements of three-terminal devices include TPT (thin film transistor (field effect transistor whose gate is insulated from the semiconductor substrate by a thin layer of silicon dioxide)),
Si-MOS (Si-metal oxide)
selconductor field-effect
transistor)S OS (Silicon)
on 5apphire).

In the smectic A phase, the molecular long axis direction is restricted to only one direction, so orientation control is much easier than in the xyl smectic C phase.

By using the device of the present invention, the orientation of the smectic A phase can be realized in a short time, so the smectic A phase can be produced by the same method as that currently used to manufacture liquid crystal display elements using nematic liquid crystal materials. It is possible to manufacture a light modulation element using the liquid crystal shown in FIG.

When a liquid crystal substance exhibiting a xylsmectic C phase is filled into a gap of about 2 μm to realize a xylsmectic C phase, two types of molecular long axis directions stably exist. Therefore, if -axis orientation is controlled, the balance between the two types of stable states will be disrupted. On the other hand, if the orientation is controlled in two axial directions in order to maintain a balance between two types of stable states, there is a problem that good initial orientation cannot be obtained. On the other hand, when optical modulation is performed using the smectic A phase, good initial alignment can be obtained by controlling the -axis alignment. Furthermore, even if positive and negative electric fields are applied, mutually equal switching can be performed.

The light conversion speed (optical response speed) of the smectic A phase in the temperature range is about several microseconds at its fastest, and it can respond very quickly.

Note that the liquid crystal material exhibiting the smectic A phase used in the light modulation element of the present invention includes the above-mentioned smectic A phase.
In addition to liquid crystal compounds that exhibit phases, liquid crystals that do not exhibit ferroelectricity may also be blended and used. Furthermore, a liquid crystal composition exhibiting a smectic A phase may be mixed with a dye. In this case, the display method may be one that utilizes light absorption of the dye. That is, this is a guest-host display method using one polarizing plate.

Effects of the Invention The light modulation element of the present invention has advantages such as: 1. Initial alignment can be performed easily; 2. Ultra-thin film is not required. 2. The alignment state is resistant to mechanical shock. It has the following characteristics.

EXAMPLES The present invention will be explained below using Examples, but the present invention is not limited to these Examples.

Example 1 A liquid crystal compound represented by the following formula was filled into the gap of a liquid crystal cell having a 3.6 μm thick spacer, and two polarizing plates orthogonal to each other were placed on both sides of the liquid crystal cell.

This liquid crystal compound exhibits a smectic A phase at temperatures below 60°C.

After filling the liquid crystal cell with the liquid crystal substance, the liquid crystal cell is heated to 60° C. to bring the liquid crystal compound into a liquid state. Thereafter, by performing slow cooling at a cooling rate of about 5° C./hour using a temperature gradient method, good initial orientation was obtained.

When an electric field was applied to the smectic A phase, induced tilt (change in the orientation direction of the long axis of the molecules) could be observed. FIG. 9 shows the temperature dependence of the induced tilt θ. At 45℃, +30v is bright (ON) state, -50v is dark (OFF)
state was obtained. The brightness contrast between the bright state and the dark state was 22 times or more. Further, when the optical response speed was measured at 45° C., it was 20 μsec.

By using this element in this way, it is possible to provide a light modulation element with good initial orientation and a fast response speed.

Example 2 First, polyimide (manufactured by Hitachi Chemical Co., Ltd., PIQ-540)
0) was dissolved in N-methylpyrrolidone to prepare a coating solution having a polyimide content of 1.2%.

The coating liquid prepared as described above was applied by a spin code method at a rotational speed of 200 Orpm onto a transparent electrode of a glass substrate provided on one side of an ITO transparent electrode.

After applying the coating solution containing polyimide in this way,
This glass substrate was heated at 325° C. for 30 minutes to harden the polyimide to form a polyimide film with a thickness of 150 to 200 μm.

By rubbing the surface of the polyimide film thus formed in one direction with a nylon cloth, the polyimide film was given orientation with respect to the liquid crystal substance.

Two substrates were prepared in the same manner as above.

Separately, an adhesive main agent (manufactured by EHC, LCB-304B) and a curing agent (manufactured by EHC, LCB-310B) were added to
An epoxy resin adhesive was prepared by mixing at a weight ratio of 8:30.

Next, the above-mentioned epoxy resin adhesive was applied to the peripheral edge of the substrate on which the polyimide film was formed (on the polyimide film) using a silk printing method to form an adhesive part on the peripheral edge of the substrate. .

Separately, finely cut fibers (GP-
20) was dispersed in Freon to a concentration of 1% by weight to prepare a spacer dispersion. Note that this fiber has a g/d value of approximately 10, where d is the diameter and g is the length.
It has a shape of

The spacer dispersion prepared as described above was sprayed onto the surface of one substrate on which the adhesive part was formed, and then the two substrates were placed so that the polyimide films faced each other, and heated at 50°C for 1 hour.
5 minutes, 15 minutes at 60℃, 15 minutes at 70℃, 80℃
for 15 minutes at 125℃, 30 minutes at 170℃, and 6 minutes at 170℃.
A liquid crystal cell was created by heating and adhering for 0 minutes. The liquid crystal cell thus obtained had a gap of approximately 2 μm.

Two polarizing plates were placed on the outside of the substrate of the liquid crystal cell produced as described above so that the polarization directions were perpendicular to each other.

Next, in the gap of the liquid crystal cell prepared as described above,
A liquid crystal compound represented by the following formula was filled.

This compound exhibits a smectic A phase at temperatures below 60°C.

After filling the liquid crystal compound as described above, the liquid crystal cell was heated to 60° C. to turn the liquid crystal compound into a liquid state. Next, by employing a temperature gradient method and performing slow cooling at a cooling rate of about 1° C./minute, the liquid crystal material could be successfully initially aligned.

By applying an electric field to the thus obtained light modulation element in a state where the liquid crystal compound exhibits the smectic A phase, induced tilt (change in the orientation direction of the long axis of the molecules) was observed.

That is, by applying a voltage of +30 V at 45° C., a bright (ON) state was obtained, and by applying a voltage of −50 V, a dark (OFF) state was obtained.

The brightness contrast between the bright state and the dark state of the obtained light modulation element was 24. Furthermore, the optical response speed at 45° C. was measured to be 25 μsec. As described above, the light modulation element of the present invention containing the fiber having the characteristic of 3≦N/d≦100 has a good initial alignment state of the liquid crystal material and a fast response speed.

Example 3 A light modulation element was produced in the same manner as in Example 2, except that instead of the two polarizing plates, an aluminum reflector and a polarizing plate were placed outside the liquid crystal cell, as shown in FIG. Created.

That is, the liquid crystal compound filled in the liquid crystal cell was as described in Example 2.
This is the compound used in

CI+ 3 After filling the liquid crystal compound as described above in the same manner as in Example 2, this liquid crystal cell was heated to 60° C. to turn the liquid crystal compound into a liquid state. Then, employing the temperature gradient method,
By performing slow cooling at a cooling rate of about 1°C/minute,
Good initial alignment of the liquid crystal material was achieved.

By applying an electric field to the thus obtained light modulation element in a state where the liquid crystal compound exhibits the smectic A phase, induced tilt (change in the orientation direction of the long axis of the molecules) was observed.

That is, by applying a voltage of +30 V at 45° C., a bright (ON) state was obtained, and by applying a voltage of −50 V, a dark (OFF) state was obtained.

The brightness contrast between the bright state and the dark state of the obtained light modulation element was 24. Further, when the optical response speed at 45° C. was measured, it was 41 μsec.

A light modulation element having two polarizing plates and a layer that reflects at least light in the visible region exhibits good switching contrast and tends to have a fast response speed.

Example 4 In Example 2, liquid M was prepared using the temperature gradient method.

A light modulation element was produced in the same manner except that the initial orientation of the substance was performed by slow cooling at a cooling rate of about 1° C./minute while applying a direct current of 30 V to the liquid crystal cell.

That is, the liquid crystal compound filled in the liquid crystal cell was as described in Example 2.
This is the compound used in

CI (3) Then, as in Example 2, after filling the liquid crystal compound as described above, this liquid crystal cell was heated to 60°C to make the liquid crystal compound into a liquid state.Then, the temperature gradient method as described above was carried out. This initial orientation was 10.The initial orientation was determined by rotating the liquid crystal element on a rotating stage of the microscope and determining the initial orientation of the liquid crystal compound at its darkest point. It is the ratio of the transmitted light intensity (Lmax) at the brightest time to the transmitted light intensity (L m1n) of .

By applying an electric field to the thus obtained light modulation element in a state where the liquid crystal compound exhibits the smectic A phase, induced tilt (change in the orientation direction of the long axis of the molecules) was observed.

That is, by applying a voltage of +30 V at 45° C., a bright (ON) state was obtained, and by applying a voltage of −50 V, a dark (OFF) state was obtained.

Example 5 In Example 2, when preparing an epoxy resin adhesive, the main adhesive, curing agent, and cell gap were
13 beads (manufactured by EHC, GP-20) were added for control.
An adhesive/spacer was prepared by mixing at a weight ratio of 8:39:3, and this adhesive/spacer was applied to the peripheral edge of the substrate (on the polyimide film) using a silk printing method, as shown in Figure 10. A liquid crystal cell was manufactured in the same manner, except that the adhesive part was coated so that it had eight notches a-a8, and the liquid crystal compound was simultaneously filled into the gap from three of these notches. A light modulation element was fabricated. The liquid crystal element manufactured in this manner has a gap of 2 μm.

The liquid crystal compound filled in the liquid crystal cell produced as described above was the compound used in Example 2.

Then, as in Example 2, the liquid crystal compound was simultaneously filled from the notch as described above, and then the liquid crystal cell was heated to 60° C. to turn the liquid crystal compound into a liquid state. Next, by employing a temperature gradient method and performing slow cooling at a cooling rate of about 1° C./min, the liquid crystal material was able to be properly initially aligned (contrast: 16).

By applying an electric field to the thus obtained light modulation element in a state where the liquid crystal compound exhibits the smectic A phase, induced tilt (change in the orientation direction of the long axis of the molecules) was observed.

That is, by applying a voltage of +30 V at 45° C., a bright (ON) state was obtained, and by applying a voltage of −50 V, a dark (OFF) state was obtained.

The brightness contrast between the bright state and the dark state of the obtained light modulation element was 18. Further, when the optical response speed at 45° C. was measured, it was 33 μsec.

By using a liquid crystal cell in which a spacer having a plurality of notches is formed in this manner, the initial alignment of the light modulation element is improved, and the response speed of this light modulation element is also fast.

Example 6 The following liquid crystal compound was injected into a liquid crystal cell in which an active element prepared as shown in FIG. 11 was arranged on a glass substrate.

After C1■3 was injected, the liquid crystal cell was heated to 60°C to turn the liquid crystal compound into a liquid state. Thereafter, by performing slow cooling at a cooling rate of about 1° C./min using a temperature gradient method, a good initial orientation (contrast 8) was obtained.

When an electric field was applied to the smectic A phase, induced tilt (change in the orientation direction of the long axis of the molecules) could be observed. 45℃
At +30V, it is bright (ON) and deaf, and at -50V it is dark (
OFF) state was obtained. The contrast of adjacent pixels was 7, assuming that they were selected pixels and non-selected pixels, respectively.

Example 7 A liquid crystal cell was produced by the following method. On one of the glass substrates with an ITO transparent electrode film, polyimide coating and alignment treatment were performed in the same manner as in Example 2.

On the other glass substrate with the ITO transparent electrode film, silicon oxide was obliquely deposited.

An evaluation cell was prepared by stacking two of the glass substrates thus prepared with orientation imparted on top of each other.

First, an epoxy adhesive was applied by silk printing onto a glass substrate coated with a polyimide film in order to control the adhesion between the two substrates and the cell gap.

The epoxy adhesive is the main adhesive (manufactured by EHC■, LCB-
304B) Curing agent (manufactured by EHC@J, LCB-310
B) and beads for cell gap control (manufactured by EHC■,
GP-20) was mixed in a weight ratio of 138:30:3. One of the two glass substrates was coated with an epoxy adhesive and bonded together so that the transparent electrodes faced each other. This was cured according to the following curing conditions. That is, it was carried out at 50°C for 15 minutes, 60°C for 15 minutes, 70°C for 15 minutes, 80°C for 15 minutes, 125°C for 30 minutes, and 170°C for 60 minutes.

Two polarizing plates orthogonal to each other were placed on both sides of the cell with a cell gear tube diameter of approximately 2 μm.

l( The above liquid crystal compound was injected into the above liquid crystal cell.

After injection, the liquid crystal cell was heated to 60° C. to turn the liquid crystal compound into a liquid state. Thereafter, by performing slow cooling at a cooling rate of about 1° C./min using a temperature gradient method, a good initial orientation (contrast door) was obtained.

When an electric field was applied to the smectic A phase, induced tilt (change in the orientation direction of the long axis of the molecules) could be observed. 45℃
, bright (ON) state at +30V, dark (O
FF) state was obtained. The brightness contrast between the bright state and the dark state was 8. Further, when the optical response time was measured at 45° C., it was 63 μsec.

A light modulation element characterized by including a transparent substrate formed with an inorganic thin film imparted with liquid crystal orientation exhibits good initial orientation and has a fast response speed.

[Brief explanation of the drawing]

Figure 1 explains that the long axis of each molecule of ferroelectric liquid crystal is tilted by a tilt angle with respect to the vertical direction Z of the smectic layer, and that the direction of the tilt rotates by a fixed angle for each layer, forming a helical structure. This is a diagram. FIG. 2 is an explanatory diagram showing a state in which two types of orientation directions are possible in a conventional thin film element. FIGS. 3(a) and 3(b) are diagrams illustrating optical switching in a conventional thin film element. FIG. 4 is a diagram illustrating a conventional so-called host-guest type optical switching element. FIGS. 5 and 6 are schematic diagrams illustrating the modulation method of the present invention. FIG. 7 is a schematic cross-sectional view showing an example of the light modulation element of the present invention. FIG. 8 is a graph showing an example of a change in the amount of transmitted light with respect to a change in applied voltage. FIG. 9 is a graph showing an example of the temperature dependence of the induced tilt angle of MHPOBC. FIG. 10 shows a substrate on which adhesive parts and spacers having eight notches used in Example 5 were formed. a-a...Notch FIG. 11 is a conceptual diagram showing an example of a light modulation element having an active element. FIG. 12 is a cross-sectional view schematically showing a light modulation element having two liquid crystal cells. 121... Polarizing plate, 122... Transparent substrate, 123...
. . . Liquid crystal substance, 124 . . . Spacer, 125 . . . Transparent electrode 128 . . . Liquid crystal cell, 129 . It is. 131... Polarizing plate, 132... Transparent substrate, 133...
...Liquid crystal substance, 134...Spacer, 135...Transparent electrode, 137...Reflection layer FIG. 14 is a sectional view conceptually showing a liquid crystal element using a fiber. 142... Transparent substrate, 143... Liquid crystal substance, 145
...Transparent electrode, 147...Fiber No. 15 (a)
The figure is a plan view conceptually showing a liquid crystal element using a sealing material, and the figure (b) is an AA cross-sectional view thereof. 152...Transparent substrate, 153...Liquid crystal substance, 154
...Spacer, 155...Transparent electrode, 157...
Sealing material FIG. 16 is a sectional view conceptually showing a light modulation element having a ferroelectric layer. 162...Transparent substrate, 163...Liquid crystal substance, 165
...Transparent electrode, 166...Ferroelectric layer node 17 (a
) is a plan view conceptually showing a liquid crystal element having concentric spacers, and (b) is a cross-sectional view taken along line A-A. 172...Transparent substrate, 173...Liquid crystal substance, 175
...Transparent electrode, 146...Concentric spacer No. 18
(a) is a plan view conceptually showing a liquid crystal element having a comb-shaped spacer, and (b) is a plan view of the liquid crystal element having a comb-shaped spacer.
FIG.

Claims (18)

[Claims] (1) A liquid crystal cell in which two transparent substrates each having a transparent electrode on one surface are arranged so that the transparent electrodes face each other and a gap is formed between the substrates, and the gap is filled with the liquid crystal cell. 1. A light modulation element comprising a liquid crystal element comprising a liquid crystal material exhibiting a smectic A phase. (2) A liquid crystal cell in which two transparent substrates each having a transparent electrode on one surface are arranged so that the transparent electrodes face each other and a gap is formed by the substrates, and the gap is filled. 1. A light modulation element comprising: a liquid crystal element comprising a liquid crystal substance exhibiting a smectic A phase; and a polarizing plate disposed on the outside of at least one of the transparent substrates. (3) Two liquid crystal elements are arranged between polarizing plates arranged so that the polarization directions are perpendicular or parallel to each other, and the liquid crystal element consists of two sheets with a transparent electrode provided on one surface. A liquid crystal cell is formed by arranging transparent substrates such that the transparent electrodes face each other and forming a gap between the substrates and sealing the periphery, and the gap is filled with a liquid crystal substance exhibiting a smectic A phase. , and the retardation value of the light transmitted through the two liquid crystal elements is from 0.13 to
A light modulation element characterized in that it is within a range of 0.26 μm. (4) It consists of a layer that reflects at least visible light, a liquid crystal element, and a polarizing plate, and the liquid crystal element is disposed between the layer that reflects at least visible light and the polarizing plate. , and the liquid crystal element includes a liquid crystal cell in which two transparent substrates each having a transparent electrode on one surface are arranged so that the transparent electrodes face each other and a gap is formed between the substrates; and a liquid crystal material exhibiting a smectic A phase filled in the gap. (5) A liquid crystal cell in which two transparent substrates each having a transparent electrode on one side are arranged so that the transparent electrodes face each other and a gap is formed by the substrates, and the gap is filled with the liquid crystal cell. and a liquid crystal material exhibiting a smectic A phase, and the gap formed by the two transparent substrates has a width that allows the liquid crystal material to be aligned by the wall effect of the transparent substrates. A light modulation element characterized in that the liquid crystal material contains a fiber having characteristics expressed by the following formula: 3≦l/d≦100 (wherein d is the fiber in the above formula) , and D represents the average length of the fiber). (6) Two transparent substrates each having a transparent electrode and an alignment control layer laminated in this order on one surface are arranged so that the alignment control layers face each other and a gap is formed between the substrates. and a liquid crystal substance exhibiting a smectic A phase filled in the gap, and a liquid crystal element sealed around the substrate; A light modulation element characterized in that it is formed of an organic polymer film having a β dispersion temperature of or above. (7) A liquid crystal cell in which two transparent substrates each having a transparent electrode on one surface are arranged with a spacer in between so that the transparent electrodes face each other and a gap is formed by the substrates; It has a liquid crystal element consisting of a liquid crystal substance exhibiting a smectic A phase filled in the gap, a monodomain is formed by an interfacial effect between the spacer and the liquid crystal substance, and the spacer patterns a photosensitive polyimide precursor. 1. A light modulation element characterized in that it is formed of a polyimide-based organic polymer material obtained by. (8) A liquid crystal element is arranged between polarizing plates arranged so that their polarization axes are perpendicular or parallel to each other, and the liquid crystal element consists of two transparent substrates each having a transparent electrode on one surface. A liquid crystal cell is arranged such that the transparent electrodes face each other and a gap is formed by the substrate, and the periphery of the liquid crystal cell is sealed, and the smectic A is filled in the gap.
1. A light modulation element comprising a liquid crystal material exhibiting a phase, and further comprising a ferroelectric layer provided on the transparent electrode so as to be in contact with the liquid crystal material. (9) A liquid crystal cell in which two transparent substrates each having a transparent electrode on one surface are arranged so that the transparent electrodes face each other and a gap is formed between the substrates, and the gap is filled with the liquid crystal cell. a liquid crystal element made of a liquid crystal material exhibiting a smectic A phase, and at least one concentric spacer/alignment control layer that maintains a gap and orients the liquid crystal is disposed in the liquid crystal cell. A light modulation element characterized by: (10) A liquid crystal cell in which two transparent substrates each having a transparent electrode on one surface are arranged so that the transparent electrodes face each other and a gap is formed by the substrates, and the gap is filled with the liquid crystal cell. The liquid crystal cell has a liquid crystal element made of a liquid crystal substance exhibiting a smectic A phase, and a comb-shaped spacer/alignment control layer that maintains a gap and orients the liquid crystal is disposed in the liquid crystal cell. Characteristic light modulation element. (11) A liquid crystal cell in which two transparent substrates each having a transparent electrode on one surface are arranged so that the transparent electrodes face each other and a gap is formed by the substrates, and the gap is filled. 1. A light modulation element comprising a liquid crystal element comprising a liquid crystal material exhibiting a smectic A phase, and at least one transparent substrate constituting the liquid crystal cell comprising a flexible transparent substrate. (12) A liquid crystal cell in which two transparent substrates each having a transparent electrode on one surface are arranged so that the transparent electrodes face each other and a gap is formed by the substrates, and the gap is filled with the liquid crystal cell. It has a liquid crystal element made of a liquid crystal substance exhibiting a smectic A phase, and at least one transparent substrate constituting the liquid crystal cell is made of a flexible transparent substrate, and the thickness of the flexible transparent substrate is ( mm), elastic modulus E (Kgf/m^2
) and the width a (mm) of the gap have a relationship represented by the following formula. a^4/Et^3<0.32 (13) A liquid crystal cell formed by disposing two transparent substrates having transparent electrodes on one side that have been subjected to alignment treatment so that the transparent electrodes face each other and a gap is formed by the substrates; and a liquid crystal substance exhibiting a smectic A phase filled in the gap, the liquid crystal substance maintaining the liquid crystal cell at a temperature near the upper limit at which the liquid crystal substance exhibits the smectic A phase, and A light modulation element characterized in that the liquid crystal cell is initially aligned by applying a DC bias voltage to the liquid crystal cell. (14) Two transparent substrates each having a transparent electrode on one side, the transparent electrodes facing each other, and the substrates having a width of 1 to 3
It has a liquid crystal element consisting of a liquid crystal cell arranged so as to form a gap of μm, and a liquid crystal substance showing a smectic A phase filled in the gap, and the gap is
A light modulation element characterized in that it is formed by a spacer having a plurality of notches for simultaneously filling a gap with a liquid crystal material exhibiting a phase. (15) Two transparent substrates each having a transparent electrode on one side, the transparent electrodes facing each other, and the substrates having a width of 1 to 3
It has a liquid crystal element consisting of a liquid crystal cell arranged so as to form a gap of μm, and a liquid crystal substance exhibiting a smectic A phase filled in the gap, and among the transparent substrates constituting the liquid crystal cell. A light modulation element characterized in that a nonlinear element is disposed on at least one transparent substrate. (16) Two transparent substrates each having a transparent electrode on one side, the transparent electrodes facing each other, and the width of the substrate being 1 to 3
It has a liquid crystal element consisting of a liquid crystal cell arranged so as to form a gap of μm, and a liquid crystal substance exhibiting a smectic A phase filled in the gap, and among the transparent substrates constituting the liquid crystal cell. A light modulation element characterized in that an active element is disposed on at least one transparent substrate. (17) A liquid crystal cell in which two transparent substrates each having a transparent electrode on one surface are arranged so that the transparent electrodes face each other and a gap is formed by the substrates, and the gap is filled. A light modulation element comprising a liquid crystal element comprising a liquid crystal material exhibiting a smectic A phase, and further comprising an organic thin film capable of orienting the liquid crystal material on at least one surface of the transparent electrode. . (18) A liquid crystal cell in which two transparent substrates each having a transparent electrode on one side are arranged so that the transparent electrodes face each other and a gap is formed between the substrates, and the gap is filled with the liquid crystal cell. A light modulation element comprising a liquid crystal element comprising a liquid crystal substance exhibiting a smectic A phase, and further comprising an inorganic thin film capable of orienting the liquid crystal substance on at least one surface of the transparent electrode. .