JPH0455811A - Liquid crystal device and method for modulating light with the device - Google Patents

Abstract

PURPOSE:To attain a dark state having sufficient darkness and to enhance contrast by filling a liq. crystal substance contg. a specified liq. crystal compd. into a cell and setting this cell between polarizing plates at + or -10 deg. angle to a position at which transmitted light becomes darkest or lightest. CONSTITUTION:Two polarizing plates are arranged so that planes of polarization formed by the plates make 70-100 deg. angle. A liq. crystal substance contg. a liq. crystal compd. represented by formula I is filled into a cell and this cell is set between the polarizing plates at + or -10 deg. angle to a position at which transmitted light becomes darkest or lightest. In the formula I, R is 3-20C alkyl, 3-20C alkoxy, etc., each of X and Y is -COO-, -OCO-, etc., each of A and B is a group represented by formula II, etc., R* is a group represented by formula III, etc., and each of m and n is an integer of 0-2.A dark state having sufficient darkness can be attained and contrast between light and dark states is remarkably enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel liquid crystal element, a light modulation method using this element, and a display method using this light modulation method. More specifically, the present invention relates to a novel liquid crystal element using a liquid crystal material containing ferroelectric liquid crystal, a light modulation method using this liquid crystal element, and a display method using this light modulation method.

Tomo! 101 E11 Various proposals have been made regarding light modulation elements using ferroelectric liquid crystals.

One method for driving such a light modulation element is to use a liquid crystal cell in which a gap of about 2 μm formed between two transparent substrates is filled with ferroelectric liquid crystal exhibiting a chiral smect C layer. .

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. In this state, as shown in FIG. 1, the long axis direction of the liquid crystal molecules 11 gradually changes direction due to the interaction between the molecules.
It forms a helical structure (Figure 1).

However, for example, when a liquid crystal material is filled into a gap of about 2 μm formed by two glass substrates, the orientation state of the liquid crystal material is affected by the glass substrates, etc., and the spiral structure is released, resulting in the formation of the liquid crystal material shown in Figure 2. As shown, the transparent substrate 20
When viewed from above, the liquid crystal molecules 21 exhibit two stable states. In such a stable state, the guipoles in the direction perpendicular to the molecular long axis of the liquid crystal molecules are in opposite directions to each other in the dimorphic stable state, so by applying an electric field, the stable state of the liquid crystal substance can be changed. It is possible to transition between the two forms as described above.

Then, a liquid crystal cell like the one above is placed between two polarizing plates whose polarization directions are perpendicular to each other, so that when the liquid crystal substance assumes one stable state, it becomes dark (so that the amount of transmitted light decreases).
By arranging them, the amount of transmitted light can be controlled.

In this method, since the stable state of liquid crystal molecules is said to exist in only two forms as mentioned above, once the liquid crystal substance is in a stable state by applying an electric field, the electric field is applied to the liquid crystal material. It is said that even if it is removed, the liquid crystal substance does not shift to another stable state, and therefore, such a light modulation element is said to have a memory effect.

However, in reality, if a liquid crystal substance in a stable state is left without applying an electric field, a part of the liquid crystal substance may shift to another stable state, and the light modulation element has a sufficient memory effect, i.e. It is difficult to maintain a stable state for a long period of time without applying an electric field to a liquid crystal material that is in a stable state, and in order to maintain a stable state, that is, a bright state and a dark state, it is necessary to apply a certain amount of electric field. need to be applied.

As described above, in the conventional method, it is necessary to apply an electric field even when obtaining a dark state, and in many cases, it is difficult to achieve a sufficiently dark dark state.

For this reason, it has not been possible to obtain a sufficient brightness ratio between the bright state and the dark state, that is, sufficient contrast.

Purpose of the Invention The present invention provides a method for achieving a dark state with sufficient darkness, in view of the fact that in the prior art, a light modulation method and a light modulation element with sufficient contrast have not been obtained as described above. It is an object of the present invention to provide a liquid crystal element with high contrast and a light modulation method using such a liquid crystal element.

The light modulation element of the present invention includes two transparent substrates arranged to form a gap filled with at least a liquid crystal material, and a transparent substrate formed on opposing surfaces of the two transparent substrates. In a liquid crystal element consisting of a cell consisting of an electrode, a liquid crystal substance filled in the gap between the cells, and two polarizing plates placed on both sides of the cell, the plane of polarization formed by the polarizing plates is , the two polarizing plates are arranged at an angle of 70 to 110 degrees, and a cell filled with a liquid crystal substance between the polarizing plates is at a cell position where transmitted light is the darkest or a cell position where the transmitted light is the brightest. ±1 against
The liquid crystal material is arranged at an angle of 0 degrees, and is characterized in that the liquid crystal material includes a liquid crystal compound represented by the following formula [rl.

, A and B each independently represent a group selected from the group consisting of, R-rich is ... [rl, where, in the formula [rl, R is a carbon atom number of 3 to 20
is a type of group selected from the group consisting of an alkyl group having 3 to 20 carbon atoms, an alkoxy group having 3 to 20 carbon atoms, and a halogenated alkyl group having 3 to 20 carbon atoms, and x and Y are each independently -COO-1 -OCO
-1 represents a group selected from the group consisting of -1, and m and n each independently represent an integer of 0 to 2. However, m and n never become 0 at the same time.

The light modulation method according to the present invention includes two transparent substrates arranged to form a gap filled with at least a liquid crystal substance, and transparent electrodes formed on opposing surfaces of the two transparent substrates. A light modulation method in which an electric field is applied to a liquid crystal element consisting of a cell consisting of a cell, a liquid crystal substance filled in a gap between the cells, and two polarizing plates disposed on both sides of the cell, the polarizing plates The two polarizing plates are arranged so that the plane of polarization formed by Or ± relative to the brightest cell position
They are arranged at an angle of 10 degrees, and are characterized in that the liquid crystal substance contains the liquid crystal compound represented by [1] above.

Furthermore, the display element and display method of the present invention are characterized by using the above liquid crystal element.

According to the liquid crystal element of the present invention and the light modulation method using this liquid crystal element, it is possible to achieve a sufficiently dark dark state, so that the contrast between the bright state and the dark state is not only extremely high, but also , it becomes possible to ensure good memory performance.

DETAILED DESCRIPTION OF THE INVENTION Next, the liquid crystal element and light modulation method of the present invention will be specifically described.

First, the liquid crystal composition used in the present invention will be explained.

The liquid crystal composition used in the present invention contains at least one type of carboxylic acid ester represented by the following formula [1].

... [1] However, in the formula [rl, R has 3 to 20 carbon atoms
represents one type of group selected from the group consisting of an alkyl group having 3 to 20 carbon atoms, an alkoxy group having 3 to 20 carbon atoms, and a halogenated alkyl group having 3 to 2 o carbon atoms.

In the above formula [zl, when R is an alkyl group having 3 to 20 carbon atoms, such alkyl group may be in any form of linear, branched, or alicyclic. The molecules of carboxylic acid esters in which R is a linear alkyl group exhibit excellent liquid crystallinity because they have a rigid structure in which the molecules extend straight. Such a linear alkyl group is preferably an alkyl group having 3 to 20 carbon atoms, and specific examples of such alkyl groups include hexyl group, heptyl group, octyl group, decyl group, and dodecyl group. group, tetradecyl group, hexadecyl group, octadecyl group, and the like.

Further, when R is a halogenated alkyl group having 3 to 20 carbon atoms, examples of the halogenated alkyl group include F
, CQ, Br, and groups substituted with halogen atoms such as

Further, when R is an alkoxy group having 3 to 20 carbon atoms, examples of such an alkoxy group include an alkoxy group having an alkyl group as described above. Specific examples of such alkoxy groups include hexoxy, heptoxy, octyloxy, decyloxy, dodecyloxy, tetradecyloxy, heptadecyloxy, hexadecyloxy and octadecyloxy groups. be able to.

Among the compounds having R as described above, compounds having an alkoxy group exhibit particularly excellent liquid crystallinity.

In addition, in the above formula [1], X and Y are each independently -COO-1-OCO
Represents a group or single bond selected from -1. Among these, considering the linearity of the molecule, it is desirable that at least one of X and Y, preferably both, be -COO-.

In the above formula [rl, A and B each independently represent a group selected from the group consisting of.

Among these groups, when the carboxylic acid ester compound of the present invention is used as a liquid crystal compound, in consideration of the properties as a liquid crystal substance, the following are preferable.

In addition, in the formula [rl, R'' is Represents a group selected from the group consisting of.

Among these groups, the following groups are preferred in consideration of properties as a liquid crystal material.

Moreover, in Formula [1], m and n each independently represent an integer of 0 to 2. However, in the above-mentioned formula [rl, both m and n do not become 0 at the same time.

In particular, when this carboxylic acid ester compound is used as a liquid crystal compound, m is preferably 1 or 2.

Furthermore, in the above formula [I], the naphthyl group is 1.5-naphthyl group 1.6-naphthyl group 2.6-naphthyl group and 1.7-Naphthyl group may be mentioned.

Particularly in the present invention, it is preferable that the entire molecule is linear, and therefore, the naphthyl group is particularly preferably a 2.6 naphthyl group.

Therefore, as a preferable example of the carboxylic acid ester compound represented by the above formula [I], specifically, the following formulas [11 to [8]
] Compounds represented by the following can be mentioned.

[5] ・ [1] ... [6... [2] [7] ... [3] ... [4... [8] The above carboxylic acid ester compounds can be It can be manufactured by using a combination of synthetic techniques.

For example, the above carboxylic acid ester compound can be synthesized according to the synthetic route shown below. For example, by combining 6-n-alkoxynaphthalene-2-carboxylic acid and 4-hydroxybenzoic acid benzyl ester,
In the presence of N,N'-dimethylaminopyridine, 4-(6'-n -Alkoxy-
2'-naphthoyloxy)benzoic acid benzyl ester is obtained.

4-(6′-n-alkoxy 2°-naphthoyloxy)benzoic acid benzyl ester obtained as described above was added to a solvent such as tetrahydrofuran, and palladium/
4-(6'-n-alkoxy-2'-naphthoyloxy)benzoic acid is obtained by reduction using hydrogen gas in the presence of a reduction catalyst such as carbon.

Next, in the presence of 4-No-dimethylaminopyridine, using methylene chloride as a solvent, while dropping a methylene chloride solution containing N,N'-dicyclohexylcarbodiimide, hydroxybenzoic acid and an alcohol having an asymmetric carbon were added. The carboxylic acid ester compound used in the present invention can be obtained by reacting the ester compound obtained from the above with the 4-(6'-n-alkoxy-2'-naphthoyloxy)benzoic acid obtained in the above step. can be obtained.

Note that the above method is an example of a method for producing the carboxylic acid ester compound used in the present invention, and the carboxylic acid ester compound used in the present invention is not limited by this production method.

For example, among the carboxylic acid ester compounds represented by the formula [I] obtained as described above, the compound represented by the following formula [4] exhibits particularly excellent liquid crystal properties.

...[4] Table 1 shows the phase transition temperature of the compound represented by the above formula [4], which is particularly excellent as a liquid crystal compound. In the present invention, Cry represents a crystalline phase, SmC represents a chiral smectic phase, SmA represents a smectic A phase, and Iso represents an isotropic liquid.

Table 1 Compound Cry-8mC” SmC寥-SmA
SmA-Is.

[4] 76℃ 125℃ 18
3°C Among the liquid crystal compounds included in the compound represented by the above formula [I], as illustrated in Table 1, in a wide temperature range,
Many compounds exhibit a smectic phase.

Hitherto, when a liquid crystal compound is used alone, almost no liquid crystal compound is known which exhibits a smectic phase in a range of about 100° C. like the above-mentioned compound.

That is, conventionally, in liquid crystal elements, liquid crystal substances exhibiting any one of the following phases are used: chiral smectic C phase, chiral smectic F phase, chiral smectic C phase, chiral smectic H phase, chiral smectic E phase, and chiral smectic phase. However, even if a liquid crystal material exhibiting a phase other than the chiral smectic C phase is used, the response speed of the liquid crystal element is low, so it was thought that it would be advantageous in practice to drive the device in the chiral smectic C phase. .

However, by using the method of driving a liquid crystal element in the chiral smectic A phase as already proposed by the present inventor (see Japanese Patent Application No. 64-3632), it is possible to generate not only the chiral smectic C phase but also the chiral smectic A phase. However, it can be driven. Therefore, by using a liquid crystal compound containing a carboxylic acid ester compound as described above, not only can the operating temperature of the liquid crystal element be widened, but also a liquid crystal element filled with a liquid crystal substance containing such a liquid crystal compound can be It also has excellent high-speed response.

The above liquid crystal compounds can be used alone or in combination with other liquid crystal compounds.

For example, the liquid crystal compound of the present invention can be used as a main ingredient of a smectic liquid crystal composition or as an auxiliary agent of a liquid crystal composition whose main ingredient is another compound exhibiting a smectic phase. That is, the content of the carboxylic acid ester compound in the liquid crystal substance constituting the liquid crystal element of the present invention is determined as appropriate, taking into account the characteristics of the liquid crystal compound used, the viscosity of the composition, the operating temperature of the liquid crystal element, the intended use, etc. However, in the present invention, the content of the carboxylic acid ester compound in the liquid crystal substance is usually in the range of 1 to 99 parts by weight, preferably 5 to 75 parts by weight. Ru. Further, the liquid crystal substance used in the present invention may contain the above-mentioned carboxylic acid ester compound alone, or may contain two or more kinds in combination.

In the liquid crystal substance used in the present invention, examples of liquid crystal compounds that can be used together with the carboxylic acid ester compound represented by the above formula [r] include (+) -4' -
(2"-methylbutyloxy)phenyl-6-octyloxynaphthalene-2-carboxylic acid ester, 4'-decyloxyphenyl-6-((+)-2"-methylbutyloxy)naphthalene-2-carboxylic acid ester In addition to liquid crystal compounds such as , azoxy liquid crystal compounds such as , compounds having a cyclic structure such as or , and liquid crystal compounds having an asymmetric carbon such as and .

Furthermore, (c4H9)o-@coo@c, o kl(C7Hts
)o-◎coo@CN, benzoic acid ester liquid crystal compounds such as (C5■1□
)<E)Coo◎CN (CsHt□) (E)Coo@0-C3H,.

Cyclohexylcarboxylic acid ester liquid crystal compounds such as , phenyl liquid crystal compounds such as 'l I C5-◎→@CN, Schiff base liquid crystal compounds such as , terphenol liquid crystal compounds such as , etc. and pyrimidine liquid crystal compounds.

In addition, when forming, for example, a display element using the above-mentioned liquid crystal compound, in addition to the above-mentioned carboxylic acid ester compound and other liquid crystal compounds, for example, a conductivity imparting agent, a life-improving agent, etc. Additives that can be added to ordinary liquid crystal compositions may also be added.

The liquid crystal substance used in the present invention can be produced by mixing the above carboxylic acid ester compound and, if desired, other liquid crystal compounds and additives.

The liquid crystal element of the present invention filled with the liquid crystal material as described above basically consists of two transparent sheets arranged to form a gap 34 filled with the liquid crystal material, as shown in FIG. Substrates 31a, 31b, and these two transparent substrates 31a,
A transparent electrode 32a formed on the facing surface of 31b,
32b and a gap 34 between this cell 33
The cell 33 is made up of a liquid crystal material 35 filled in the cell 33 and polarizing plates 36a and 36b placed on each side of the cell 33.

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

In addition, when using a glass substrate, in order to prevent deterioration of the liquid crystal material eluted with alkaline components, an undercoat layer (mainly composed of, for example, silicon oxide) is coated on the surface of the glass substrate.
An unnecessary component permeation prevention layer) can also be provided.

For example, in the case of a glass substrate, the thickness of the transparent substrate is usually 0.01 to 1. It is within the range of ○l.

Further, in the present invention, a flexible transparent substrate can also be used as the transparent substrate. In this case, a flexible transparent substrate may be used as at least one of the transparent substrates, and both may be flexible substrates.

A polymer film or the like can be used as such a flexible transparent substrate.

A transparent electrode is provided on the surface of such a transparent substrate.

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

The thickness of the transparent electrode is usually 100 to 2000. It is within the range of 1000 t angstroms.

A transparent substrate provided with such a transparent electrode may further include an alignment layer or a ferroelectric layer on the transparent electrode. For example, the alignment layer can be formed by chemically adsorbing an organic silane coupling agent, a carboxylic acid polynuclear complex, or the like. It can also be formed by obliquely depositing silicon oxide or the like. Furthermore, an alignment layer can also be formed by coating a polyimide resin on a transparent electrode and then rubbing it in a certain direction.

Furthermore, the alignment layer or the like may be formed 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 a gap is formed between the transparent substrates to be filled with a liquid crystal material.

The width of the gap formed as described above is usually 1 to 1
0 μm, preferably 1 to 5 μm.

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, the alignment film and the spacer can be integrated by using a concentric spacer or a comb-shaped spacer that acts as an alignment film.

Furthermore, in addition to the above-mentioned spacers, fibers may be incorporated into the liquid crystal material, and the transparent substrates may be held by the fibers so as to form a certain gap.

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

Such granules are made of melamine resin, urea a fat, benzoguanamine resin, etc. and have a particle diameter of 1 to 1.
Particulate matter of 0 μm may be mentioned.

The two transparent substrates arranged with a gap formed as described above are usually bonded together by sealing the periphery with a sealing material.

As such a sealing material, epoxy resin, silicone resin, etc. can be used.

Furthermore, this epoxy resin or the like may be modified with an acrylic material, silicone rubber, or the like.

The gap in the liquid crystal cell having the above structure is filled with a liquid crystal substance containing a carboxylic acid ester compound represented by the above formula [r].

Such a liquid crystal substance filled in the gap of the liquid crystal cell can be aligned using a uniaxial alignment control method such as a temperature gradient method using a spacer edge or a surface treatment method using an alignment film. Further, in the present invention, the initial orientation of the liquid crystal material can be performed by applying an electric field using a DC bias voltage while heating the liquid crystal material.

The liquid crystal cell filled with the liquid crystal material and initially oriented in this manner is placed between two polarizing plates. These two polarizing plates are arranged so that the angle between the polarization planes of each polarizing plate is 70 to 110 degrees. and,
It is preferable to arrange the polarizing plates so that the polarization directions of the two polarizing plates are perpendicular to each other, that is, the angle is 90 degrees.

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.

In the present invention, the liquid crystal cell as described above has an angle (rotation angle) between the polarizing plates arranged as described above within a range of ±10 degrees from a state where the amount of transmitted light is the least (i.e., the darkest state). It can be placed between two polarizing plates so as to form a darkest state, preferably in the darkest state. Furthermore, between the polarizing plates arranged as described above in the liquid crystal cell described above, an angle (rotation angle) is formed in which the amount of transmitted light is greatest (i.e., an angle (rotation angle) within the range of 11 degrees and 10 degrees at the brightest point). The light source can be placed between two polarizing plates so as to preferably be in the brightest state.

By applying an electric field to the liquid crystal element of the present invention having the above-described configuration, the liquid crystal element can be driven.

That is, the frequency of the liquid crystal element of the present invention is usually from IH2 to
100KHz, preferably 10H2 to 10KHz,
It can be driven by applying an electric field controlled to usually 0.01-60 Vpp/μm, preferably 0.05 to 30 Vpp/μm.

When the liquid crystal element of the present invention is driven by applying an electric field, by changing the width of the waveform (driving wave) of the applied electric field, the amount of light transmitted through the liquid crystal element draws two types of hysteresis curves. It becomes like this. That is, the inventor:
Using the same liquid crystal element, we succeeded in developing memory properties using two driving methods. One of these is a drive method that uses a so-called bistable type, and the other is a drive method that uses a so-called princess type.

A liquid crystal element using MHPOBC as a liquid crystal material is known as an example of a liquid crystal element exhibiting constant constant, but this liquid crystal element only exhibits constant constant and hardly exhibits bistability.

The liquid crystal element of the present invention makes it possible to select either the bistable or deterministic stable state by simply changing the width of the applied electric field waveform (drive wave) using one type of liquid crystal element. It can be achieved.

FIG. 4 is an example of an oscilloscope waveform showing the relationship between the amount of transmitted light and the applied voltage of a liquid crystal element exhibiting constant property and FIG. 5 showing bistability.

The liquid crystal element used here consists of a liquid crystal cell filled with a liquid crystal substance placed between two polarizing plates arranged so that the polarization planes are perpendicular to each other, so that the liquid crystal cell is placed in the darkest state when no electric field is applied. This liquid crystal element is shown in Fig. 4.
An example of an oscilloscope waveform when a 0 Hz triangular wave is applied is shown, and FIG. 5 shows an example of an oscilloscope waveform when a 100 Hz triangular wave is applied.

In the liquid crystal element in which the liquid crystal cell and the polarizing plate are arranged to be in the darkest state as described above, an electric field with a relatively low frequency, for example, an electric field with a frequency of 0.001 to 50 Hz, preferably 0.1 to 30 Hz, is applied. By applying , a good stable state can be achieved. As the frequency of the applied electric field increases, the oscilloscope waveform gradually shifts to a bistable state as shown in FIG.
By applying an electric field of 00 KHz, preferably 70 Hz to I0 KHz, a good bistable state can be achieved.

In such a liquid crystal element, for example, as shown in FIG. 4, a dark state can be achieved with an applied voltage of OV, and in this case, the contrast becomes very high.

Figures 6 and 7 show the oscilloscope waveforms of a liquid crystal element in which a liquid crystal cell filled with a liquid crystal substance is placed in the brightest state between two polarizing plates arranged so that the polarization planes are perpendicular to each other. An example is shown.

Fig. 6 shows an example of an oscilloscope waveform when a 10Hz triangular wave is applied to this liquid crystal element, and Fig. 7 shows an example of an oscilloscope waveform when a 100Hz triangular wave is applied. ing. This liquid crystal element also exhibits the same tendency as the liquid crystal element described above, and, for example, a bistable state is achieved by applying an electric field of a relatively high frequency to such a liquid crystal element.

The electric field applied to such a liquid crystal element preferably has a waveform selected from a rectangular wave (or pulse wave), a triangular wave, a sine wave, and a combination thereof. When applying a rectangular wave (or a pulse or a combination of both) of such a waveform electric field, the width of the electric field should be set to 10 milliseconds or less, preferably 0.01 to 1
By setting the time within the range of 0 milliseconds, the driving speed of the liquid crystal element can be increased, and in this range, the liquid crystal element of the present invention can be used as a bistable liquid crystal element. In addition, by making the width of this electric field larger than 10 milliseconds, preferably within the range of 33 to 1000 milliseconds, the liquid crystal element of the present invention can be used in areas where it is not necessary to drive at very high speeds. It can be used as a regular liquid crystal element. Here, the width of the electric field means the length (ie, time) of the electric field maintained at a predetermined voltage, for example in the case of a rectangular wave.

This liquid crystal element has an O
An electric field can be applied varying through v. In the driving method for producing a bistable state as shown in FIGS. 5 and 7, it is possible to form a hysteresis curve exhibiting good bistability by varying the voltage between -30 and +30 V, for example. can. An electric field can be similarly applied to a liquid crystal element exhibiting a constant property.

Further, the electric field having the above waveform may be applied to this liquid crystal element while being varied between 0 and a positive voltage, or may be applied while being varied between 0 and a negative voltage. . That is, for example, in FIG. 4, an optical modulation method that utilizes the light transmittance shown by the hysteresis curve formed on the positive voltage side by applying an electric field with a voltage varying within the range of 0 to +30V is adopted. Similarly, an optical modulation method that utilizes the light transmittance represented by the hysteresis curve formed on the negative voltage side by applying an electric field with a voltage varying within the range of O to -30V is adopted. You can also do that.

The liquid crystal element of the present invention is an element that can use two driving methods as described above, and has the advantage that memory performance can be ensured by changing the driving method depending on the usage conditions. are doing.

The liquid crystal element as described above can be used as a normal liquid crystal element, but is particularly useful as a display element.

Examples of display elements include large screen displays, in-vehicle multi-information displays, and in-vehicle navigation displays.

Such a display element can be driven as a bistable display element or a regular display element using the above-described driving method depending on the application.

Effects of the Invention According to the liquid crystal element of the present invention and the light modulation method using this liquid crystal element, it is possible to achieve two stable states of a bistable state and a stable state with one type of liquid crystal element. .

By using the liquid crystal element of the present invention, it is possible to achieve a sufficiently dark dark state, which not only increases the contrast between the bright and dark states but also ensures good memory performance. It becomes possible to do so.

Next, examples of the present invention will be shown, but the present invention is not limited to these examples.

Example I 4-[4°-(6°'-n-hebutyloxy-2'°-
naphthoyloxy)benzoyloxy]benzoic acid R-1
``'-Trifluoromethylheptyl ester synthesis step 1 4-benzyloxybenzoic acid 1.4 g (5 mmol)
, R-1-trifluoromethyl heptatool 0.92
g (5 mmol), 0.12 g (1 mmol) of 4-N,N-dimethylaminopyridine and 20 m of methylene chloride.
10 ml of a methylene chloride solution containing 1.03 g (5 mmol) of N,N'-dicyclohexylcarbodiimide was added dropwise to the mixture of Example 1 at room temperature over 1 hour with stirring. Furthermore, the reaction was continued for 10 hours at room temperature.

The reaction mixture was filtered and the resulting filtrate was concentrated.

The concentrate was separated using column chromatography to obtain 4-benzyloxybenzoic acid R-1'-)lifluoromethyl-heptyl ester 1, which is a colorless and transparent liquid.
．． 75 g (4.4 mmol) were obtained.

2nd stage 4-benzyloxybenzoic acid R-1 obtained in the 1st stage
°-Trifluoromethyl-heptyl ester 1.58g
(4 mmol), 0.5 g of 5% palladium/carbon, and 30 ml of ethyl acetate was bubbled with hydrogen for 9 hours at room temperature and under normal pressure with stirring. The reaction mixture was filtered using Celite, which is a filter aid, and the resulting filtrate was concentrated.

4-Hydroxybenzoic acid R, which is a colorless viscous liquid, is obtained by separating the concentrate using column chromatography.
-1'-) Lifluoromethyl-heptyl ester 1.7
5 g (4.4 mmol) were obtained.

Third stage 6-n-heptyloxynaphthalene-2-carboxylic acid 2
．． 43 g (8.5 mmol), 0.012 g (0.1 mmol) of 4-N,N-dimethylaminopyridine and 30 ml of methylene chloride were added with N,N'-
Dicyclohexylcarbodiimide 1.75 g (8,
10 ml of a methylene chloride solution containing 5 mmol) was added dropwise over 1 hour while stirring and cooling with ice.

The reaction mixture was filtered and the resulting filtrate was concentrated.

By separating the concentrate using column chromatography, a white solid, 4-(6'-hebutyloxy-2
'-naphthoyloxy)benzoic acid benzyl ester2.
72 g (5.5 mmol) were obtained.

Fourth stage 4-(6°-hebutyloxy-2- obtained in the third stage)
Naphthoyloxy)benzoic acid benzyl ester 2.33
g (4.7 mmol), 5% palladium-carbon 1.
Hydrogen was bubbled into a mixture of 0 g and 30 ml of tetrahydrofuran at room temperature for 8 hours under normal pressure and stirring.

The reaction mixture was filtered using Celite as a filter aid,
The resulting filtrate was concentrated. By recrystallizing the concentrate from toluene, 42 g of 4-(6'-n-heptyloxy-2-naphthoyloxy)benzoic acid was obtained as a white solid.
(3.5 mmol) was obtained.

5th step 4-(6'-n-heptyloxy- obtained in the 4th step)
0.41 g (1 mmol) of 2-naphthoyloxy)benzoic acid, 4-hydroxybenzoic acid R- obtained in the second stage
1'-trifluoromethyl-heptyl ester 0.30
g (1 mmol), 0.21 g (1 mmol) of N,N'-dicyclohexylcarbodiimide in a mixture of 0.012 g (0.1 mmol) of 4-N,N-dimethylaminopyridine and 10 ml of methylene chloride. 2 ml of a methylene chloride solution containing the above was added dropwise over 1 hour at room temperature with stirring. The mixture was further reacted at room temperature for 8 hours.

The reaction mixture was filtered and the resulting filtrate was concentrated.

The concentrate was separated using column chromatography to obtain 0.63 g of a colorless semi-solid.

The value of the FD-mass spectrum of this semi-solid is M/e = 73
It was 9. This result and iH-NMR of this compound
From the analysis results using a spectrum chart, this compound was found to be the target R-11°-trifluoromethyl 4-[4'-(6°'-n-hebutyloxy-21-naphthoyloxy)benzoyloxy]benzoate. It was identified as heptyl ester (exemplary compound [4]).

A liquid crystal substance (liquid crystal composition) was prepared.

...[4] ...(Cr-1) Table 2 shows the phase transition temperature of this liquid crystal composition.

Furthermore, the phase transition temperature of the compound represented by the above formula (Cr-1,) is also listed in Table 2.

Table 2 Cry.

SmC” mA l5o.

Formula [4] ・ 76 ・ 125 ・ 183 composition ・ 〈-30 ・ 52 ・ 96 (C
r-1) ・-13...-6 As shown in Figure 1, two sheets of polyimide (Hitachi Chemical - Manufactured by PIQ-54
The carboxylic acid ester compound [2] represented by the above formula [2] was melted in a cell in which an orientation control film (thickness: 150 angstroms) consisting of 00) was formed, and the gap between the cells was brought into a reduced pressure state. Injected. The cell filled with the liquid crystal material was heated to 200°C, held at 200°C for 5 minutes, and then cooled to 60°C at a rate of It)/min to produce a liquid crystal device.

Cell conditions (a) External dimensions: Height: 2,5 am x 2, 2 an x thickness: 1.
51 (b) Substrate thickness 0.7B, substrate material glass (c) Distance between substrates: 2 μm (d) Side wall dimensions height 1,8 m x 2, 2 alIX thickness 1.5
The cell as described above was created by the following method.

Polyimide was applied onto a glass substrate with an ITO transparent electrode film. That is, polyimide (manufactured by Hitachi Chemical Co., Ltd.,
PIQ-5400) was applied onto the ITO transparent electrode by a spin-coding method.

Polyimide was prepared using N-methylpyrrolidone as a solvent.
It was diluted to 2% and spin coded at 2000 rpm. When this was heated at 325° C. for 30 minutes and cured, a polyimide film with a thickness of 150 to 200 angstroms was created. Thereafter, the polyimide film was rubbed in one direction with a nylon cloth to impart liquid crystal orientation to the polyimide film.

A cell was created by stacking two glass substrates coated with the polyimide film thus created.

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

The epoxy adhesive is the main adhesive (manufactured by EHC-, LCB-
304B), curing agent (manufactured by EHC-, LCB-304B)
and beads for cell gap control (manufactured by EHC@,
GP-20) in a weight ratio of 130:30:3.

An epoxy adhesive was applied to one of the two glass substrates, and the substrates were arranged so that the polyimide films of each substrate faced each other. Then, this board was heated to 50℃ for 1
5 minutes, 15 minutes at 60℃, 15 minutes at 70℃, 80℃
for 15 minutes at 125°C and 15 minutes at 170°C for 60 minutes.
The epoxy adhesive was cured by heating for a minute, and the substrates were bonded together.

The thus prepared cell having a cell gap of approximately 2 μm was filled with the liquid crystal composition prepared as described above, and its characteristics were evaluated.

A liquid crystal cell filled with the liquid crystal substance prepared as described above was placed between two polarizing plates whose polarization planes were perpendicular to each other so as to be at the darkest position to prepare a liquid crystal element.

When a triangular wave of 30 VP- was applied to this liquid crystal element and the transmitted light intensity was measured, the oscilloscope waveform shown in FIG. 4 was obtained at 10 Hz, and the oscilloscope waveform shown in FIG. 5 was obtained at 100 Hz.

As is clear from Fig. 4, by applying a 10Hz triangular wave, this liquid crystal element has a voltage of +30
A contrast of 34 was achieved when V (or -30V) was applied.

Further, as is clear from FIG. 5, by applying a 100 Hz triangular wave, this liquid crystal element was able to achieve a contrast of 15 between when −12 V was applied and when +12 V was applied.

The liquid crystal element of the present invention, in which the liquid crystal cell is arranged so as to be at the darkest position between two polarizing plates whose polarization planes are perpendicular to each other, can achieve a dark state with an applied voltage Ov, especially at low frequencies. , the contrast becomes very high.

The above contrast was determined by varying the voltage applied to the liquid crystal element, measuring the intensity of transmitted light when open and when dark, and calculating the ratio of (open)/■ (dark).

Next, a liquid crystal cell filled with the liquid crystal material prepared as described above was placed between two polarizing plates whose polarization planes were perpendicular to each other so as to be at the brightest position to prepare a liquid crystal element.

When a triangular wave of 30 Vp-p was applied to this liquid crystal element and the transmitted light intensity was measured, the oscilloscope waveform shown in FIG. 6 was obtained at 10 Hz, and the oscilloscope waveform shown in FIG. 7 was obtained at 100 Hz.

From this result, the liquid crystal element of the present invention, in which the liquid crystal cell was arranged at the brightest position between two polarizing plates with perpendicular polarization planes, was able to ensure good memory performance, especially at high frequencies.

[Brief explanation of drawings]

Figure 1 explains that the long axis of each molecule of a ferroelectric liquid crystal is tilted by a tilt angle with respect to the vertical direction 2 of the smectic layer, and that the tilt direction 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. FIG. 3 is a cross-sectional view schematically showing an example of the liquid crystal element of the present invention. 31a, 31b...Transparent substrates 32a, 32b...Transparent electrode 33...Cell 34...Gap 35...Liquid crystal material 36a, 36b---Polarizing plate FIG. 4 and FIG. It is a photograph of an oscilloscope waveform showing the relationship between applied voltage and transmitted light intensity when a triangular wave electric field is applied to a liquid crystal element of the present invention in which a liquid crystal cell is arranged so as to be in a dark state. FIGS. 6 and 7 are photographs of oscilloscope waveforms showing the relationship between applied voltage and transmitted light intensity when a triangular electric field is applied to a liquid crystal element of the present invention in which liquid crystal cells are arranged so as to be in the brightest state. . Layer structure Figure 1 Figure 2 Layer structure

Claims (10)

[Claims] (1) A cell consisting of two transparent substrates arranged to form a gap filled with at least a liquid crystal substance, and a transparent electrode formed on opposing surfaces of the two transparent substrates, the gap between the cells In a liquid crystal element consisting of a liquid crystal material filled in the cell and two polarizing plates placed on each side of the cell, the plane of polarization formed by the polarizing plates is 70 to 110 degrees. A cell in which two polarizing plates are arranged and a liquid crystal material is filled between the polarizing plates is ±1 with respect to the cell position where the transmitted light is the darkest or the cell position where the transmitted light is the brightest.
A liquid crystal element arranged at an angle of 0 degrees, and characterized in that the liquid crystal substance includes a liquid crystal compound represented by the following formula [I]; ▲Mathematical formula, chemical formula,
There are tables, etc. ▼ ... [I] [However, in the formula [I], R has 3 to 3 carbon atoms.
20 alkyl group, an alkoxy group having 3 to 20 carbon atoms, and a halogenated alkyl group having 3 to 20 carbon atoms, and X and Y are each independently -COO- , -OCO
-, -CH_2CH_2-, -CH_2O-, -OCH
＿２−, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas,
There are chemical formulas, tables, etc. ▼ and -S-S- Represents a group selected from the group consisting of, or a single bond, A and B are each independently, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼▲ Numerical formulas, There are chemical formulas, tables, etc. ▼▲ There are mathematical formulas, chemical formulas, tables, etc. ▼▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼▲ There are mathematical formulas, chemical formulas, tables, etc. ▼▲ Mathematical formulas, There are chemical formulas, tables, etc. ▼ and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Represents a group selected from the group consisting of: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Numerical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc.▼ and ▲There are mathematical formulas, chemical formulas, tables, etc.▼ represents a group selected from the group consisting of, and m and n each independently represent an integer from 0 to 2 (however, m and are never 0 at the same time)]. (2) A cell consisting of two transparent substrates arranged to form a gap filled with at least a liquid crystal substance, and a transparent electrode formed on opposing surfaces of the two transparent substrates, the gap between the cells In a light modulation method in which an electric field is applied to a liquid crystal element consisting of a liquid crystal material filled in a cell and two polarizing plates placed on both sides of the cell, the plane of polarization formed by the polarizing plates is 70° The two polarizing plates are arranged at an angle of ~110 degrees, and the cell filled with a liquid crystal compound between the polarizing plates is placed at the cell position where the transmitted light is the darkest or the brightest. Te±
A light modulation method characterized in that the liquid crystal material is arranged at an angle of 10 degrees, and the liquid crystal substance contains a liquid crystal compound represented by the following formula [I]; ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ・・・[I] [However, in the formula [I], R has 3 to 3 carbon atoms.
20 alkyl group, an alkoxy group having 3 to 20 carbon atoms, and a halogenated alkyl group having 3 to 20 carbon atoms, and X and Y are each independently -COO- , -OCO
-, -CH_2CH_2-, -CH_2O-, -OCH
＿２−, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas,
There are chemical formulas, tables, etc. ▼ and -S-S- Represents a group selected from the group consisting of, or a single bond, A and B are each independently, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼▲ Numerical formulas, There are chemical formulas, tables, etc. ▼▲ There are mathematical formulas, chemical formulas, tables, etc. ▼▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼▲ There are mathematical formulas, chemical formulas, tables, etc. ▼▲ Mathematical formulas, There are chemical formulas, tables, etc. ▼ and ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Represents a group selected from the group consisting of: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Numerical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc.▼ and ▲There are mathematical formulas, chemical formulas, tables, etc.▼ represents a group selected from the group consisting of, and m and n each independently represent an integer from 0 to 2 (however, m and are never 0 at the same time)]. (3) The light modulation according to claim 2, characterized in that the voltage applied to the liquid crystal element is varied between a positive voltage and a negative voltage to change the amount of light that passes through the liquid crystal element. Method. (4) The waveform of the electric field applied to the liquid crystal element while varying between a positive voltage and a negative voltage is a waveform selected from the group consisting of a rectangular wave, a triangular wave, a sine wave, and a waveform that is a combination of these. Claim 2 or 3 characterized by
The light modulation method described in section. (5) The light modulation method according to claim 4, wherein the waveform of the electric field applied to the liquid crystal element is a rectangular wave, and the minimum width of the rectangular wave is 10 milliseconds or less. (6) The voltage applied to the liquid crystal element is varied between 0 and a positive voltage or between 0 and a negative voltage to change the amount of light that passes through the liquid crystal element. The light modulation method according to claim 2. (7) The waveform of the electric field applied to the liquid crystal element while varying between 0 and positive voltage or between 0 and negative voltage is a rectangular wave, a triangular wave, a sine wave, or a waveform that is a combination of these. 7. The optical modulation method according to claim 2, wherein the waveform is selected from the group consisting of: (8) The light modulation method according to claim 7, wherein the waveform of the electric field applied to the liquid crystal element is a rectangular wave, and the minimum width of the rectangular wave is greater than 10 milliseconds. (9) A display element using the liquid crystal element according to claim 1. (10) A display method using the modulation method according to any one of claims 2 to 8.