JP2749823B2 - Liquid crystal composition and liquid crystal device containing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid crystal composition used for a liquid crystal device used for a liquid crystal display device or a liquid crystal-optical shutter, and more particularly, to a novel liquid crystal composition having improved response characteristics to an electric field. The present invention relates to a liquid crystal composition.

(Background technology)

Conventionally, liquid crystals have been applied in various fields as electro-optical elements. Most liquid crystal devices currently in practical use are described in, for example, “Applied Physic” by M. Schadt and W. Helfrich.
s Letters "Vo.18, No.4 (1971.2.15)," Voltage-Spendent Optical Activity of a Twisted "
Nematic Liquid Crystal "(twisted nemat
ic) type liquid crystal.

These are based on the dielectric alignment effect of liquid crystal, and use the effect that the average molecular axis direction is directed in a specific direction by an applied electric field due to the dielectric anisotropy of liquid crystal molecules.
The limit on the optical response speed of these devices is said to be milliseconds, which is too slow for many applications. On the other hand, in application to a large flat display, driving by the simple matrix method is the most influential in consideration of price, productivity, and the like. In the simple matrix system, an electrode configuration in which a scanning electrode group and a signal electrode group are configured in a matrix is employed. To drive the scanning electrode group, an address signal is sequentially and selectively applied to the scanning electrode group, and the signal electrode group is applied. Employs a time-division driving method in which a predetermined information signal is selectively applied in parallel in synchronization with an address signal.

However, when the above-described TN type liquid crystal is adopted as an element of such a driving method, a scanning electrode is selected and a region where a signal electrode is not selected, or a region where a scanning electrode is not selected and a signal electrode is selected (a so-called “half”). A finite electric field is also applied to the selected point “)”. If the difference between the voltage applied to the selected point and the voltage applied to the half-selected point is sufficiently large and the voltage threshold required for aligning the liquid crystal molecules perpendicularly to the electric field is set to this intermediate voltage value, the display element is Although it operates normally, when the number of scanning lines (N) is increased, the time during which an effective electric field is applied to one selected point while scanning the entire screen (one frame) (duty ratio) Decreases at a rate of 1 / N. For this reason, the voltage difference as an effective value between the selected point and the non-selected point when the repetitive scanning is performed becomes smaller as the number of scanning lines increases, and as a result, a decrease in image contrast and crosstalk are reduced. It is an inevitable drawback. Such a phenomenon is caused by a liquid crystal having no bistability (a stable state in which liquid crystal molecules are horizontally aligned with respect to an electrode surface, and are vertically aligned only when an electric field is effectively applied. ) Is essentially unavoidable when driving (i.e., repeatedly scanning) using the time accumulation effect. In order to improve this point, a voltage averaging method, a two-frequency driving method, a multiplex matrix method, and the like have already been proposed. However, any of these methods is insufficient, and a large screen or high density display device is required. At present, the number of scanning lines has reached a plateau due to a failure to sufficiently increase the number of scanning lines.

As an improvement over the disadvantages of the conventional liquid crystal device, the use of a bistable liquid crystal device has been proposed by Clark and Lager.
proposed by wall (JP-A-56-107216,
U.S. Pat. No. 4,436,724). Generally, a ferroelectric liquid crystal having a chiral smectic C phase (SmC ^* ) or an H phase (SmH ^* ) is used as the bistable liquid crystal. This ferroelectric liquid crystal has a bistable state consisting of a first optically stable state and a second optically stable state with respect to an electric field. In contrast, for example, the liquid crystal is oriented in a first optically stable state with respect to one electric field vector, and the liquid crystal is oriented in a second optically stable state with respect to the other electric field vector. In addition, this type of liquid crystal has a property (bistability) that takes one of the above two stable states in response to an applied electric field and maintains the state when no electric field is applied.

In addition to the characteristic having bistability as described above, the ferroelectric liquid crystal has an excellent characteristic of high-speed response. This is because the spontaneous polarization of the ferroelectric liquid crystal and the applied electric field directly act to induce the transition of the alignment state, and are three to four orders of magnitude faster than the response speed due to the dielectric anisotropy and the action of the electric field.

As described above, ferroelectric liquid crystals have potentially excellent properties, and by utilizing such properties,
Significant improvements are obtained over many of the problems of the conventional TN devices described above. In particular, applications to high-speed optical shutters and high-density, large-screen displays are expected.

In the case of a simple matrix display device as described above using an element in which the ferroelectric liquid crystal layer is sandwiched between a pair of substrates,
For example, JP-A-59-193426, JP-A-59-193427,
The driving method disclosed in JP-A-60-156046 and JP-A-60-156047 can be applied.

FIG. 4 is a waveform diagram of the driving method used in the embodiment of the present invention. FIG. 5 is a plan view of a ferroelectric liquid crystal panel 51 in which the matrix electrodes used in the present invention are arranged. Fifth
In the panel 51 shown in the figure, a scanning line 52 and a data line 53 are wired so as to cross each other, and a ferroelectric liquid crystal is disposed between the scanning line 52 and the data line 53 at the intersection.

Selection information to select the scan waveform S _S of FIG. 4 (A) in which applied to the selected scanning line, the unselected scanning waveform S _N is not selected, I _S is applied to the selected data line waveform (black), I _N represents the non-selection information signal applied to the data line which is not selected (white). In the figure, (I _S −
S _S ) and (I _N −S _S ) are voltage waveforms applied to the pixels on the selected scanning line. The pixel to which the voltage (I _S −S _S ) is applied takes a black display state, and the voltage (I _S −S _S ) is black. _The pixel to which _N− S _S ) is applied takes a white display state.

FIG. 4B is a time-series waveform when the display shown in FIG. 6 is performed with the driving waveform shown in FIG. 4A.

In the driving example shown in Figure 4, the minimum application time Δt of a single polarity voltage corresponds to the write phase t ₂ time period of a one-line clearing phase t ₁ is applied to a pixel on a selected scanning line 2Δt Is set to

Now, each parameter V _S , of the drive waveform shown in FIG.
The values of V ₁ and Δt are determined by the switching characteristics of the liquid crystal material used.

Figure 7 shows the change or V-T characteristic of the transmittance T when changing the voltage drive while maintaining a constant bias ratio to be described later (V _S + V _I). Here, Δt = 50
μs, and the bias ratio V _I / V _I + V _S ) is fixed at 1/3. The waveform shown by (I _N -S _S ) shown in FIG. 4 is applied to the positive side in FIG. 7, and the waveform shown by (I _S -S _S ) is applied to the negative side. Where V ₁ , V ₃
Are called an actual drive threshold voltage and a crosstalk voltage, respectively. However, (V ₂ <V ₁ <V ₃ ) or ΔV = (V ₃ −V ₁ ) is referred to as a voltage margin, which is a voltage width in which matrix driving is possible.
V ₃ may say that the FLC matrix drive generally present. Specifically, it is a voltage value that causes switching by V _B ′ in the waveform of FIG. 4A (I _N −S _S ).
Of course, it is possible to increase the value of V ₃ by increasing the bias ratio, increasing the bias ratio corresponds to a large amplitude of a data signal, an increase in flickering in image quality, contrast It is unfavorable because it causes a decrease in
In our study, a bias ratio of 1/3 to 1/4 was practical. By the way, if the bias ratio is fixed, the voltage margin Δ
V depends strongly on the switching characteristics of the liquid crystal material, and it goes without saying that a liquid crystal material having a large ΔV is very advantageous for matrix driving.

At such a certain temperature, two states of “black” and “white” can be written to the selected pixel depending on the two directions of the information signal.
Alternatively, the upper and lower limits of the applied voltage and the width thereof (driving voltage margin ΔV) capable of maintaining the “white” state
Is unique among liquid crystal materials. In addition, since the drive margin shifts due to changes in the environmental temperature,
In the case of an actual display device, it is necessary to set an optimum driving voltage for a liquid crystal material and an environmental temperature.

However, when the display area of such a matrix display device is expanded in practical use, the difference in the existence environment of the liquid crystal in each pixel (specifically, the temperature and the cell gap difference between the electrodes) naturally increases, and the driving voltage increases. With a liquid crystal having a small margin, a good image cannot be obtained over the entire display area.

[Problems to be solved by the invention]

According to the present invention, a driving voltage margin is large so that a ferroelectric liquid crystal element can be put to practical use, and even if there is a certain degree of temperature variation on a display area of the liquid crystal element, a driving temperature margin that allows all pixels to be favorably driven in a matrix is wide. An object of the present invention is to provide a chiral smectic liquid crystal composition and a liquid crystal element using the liquid crystal composition.

[Means for Solving the Problem] The present invention provides a compound represented by the following general formula (I) (Wherein, R ₁ is a C ₁ -C ₁₈ linear or branched alkyl group optionally substituted by fluorine or an alkoxy group, and R ₂ is a C ₁ -C ₁₂ linear alkyl group. Group and X ₁
Is a single bond, -O-, And either.

Is one of ) And at least one compound represented by the following general formula (II) (Wherein, R ₃ and R ₄ are C _{1 to} C ₁₈ linear or branched alkyl groups, at least one of which is optically active. X ₂ ,
X ₃ is a single bond, -O-, Is one of A ferroelectric chiral smectic liquid crystal composition comprising at least one of the following: and a liquid crystal element comprising the liquid crystal composition disposed between a pair of electrode substrates. .

Among the compounds represented by the above general formula (I), examples of preferred compounds include those represented by the general formulas (Ia) to (Id).

Furthermore, in the above formulas (Ia) to (Id),
More preferred examples of X ₁ include a single bond, —O—, Can be mentioned.

Furthermore, in the above formulas (Ia) to (Id),
A more preferred example of R ₁ is a linear alkyl group.

In addition, as preferable examples of the compound represented by the general formula (II), X ₂ and X ₃ are (II-i) to (II-
and viii).

(II-i) X ₂ is a single bond, X ₃ is -O- (II-iv) V ₂ is a single bond, X ₃ is a single bond (II-v) X ₂ is -O-, X ₃ is -O- (II-viii) X ₂ is a single bond and X ₃ is a single bond. Further, in the compound represented by the general formula (II),
Examples of preferred compounds of R ₃ and R ₄ include (II-ix) to (II
-Xi).

(X and y are 0 to 7, and R ₅ and R ₆ are linear or branched alkyl groups) Examples of specific structural formulas of the compound represented by the general formula (I) are shown below.

Synthesis Example 1 (Synthesis of Compound No. 1-4) (I) 10 g (53.6 mmol) of trans-4-n-propylcyclohexanecarboxylic acid chloride was dissolved in 30 ml of ethanol, and a small amount of triethylamine was added thereto.
Stirred for hours. The reaction mixture was poured into ice water (100 ml), and a 6N hydrochloric acid aqueous solution was added to make the mixture acidic, followed by extraction with isopropyl ether. The organic layer was repeatedly washed with water until the washing liquid became neutral, and then dried over magnesium sulfate. After evaporating the solvent, the residue was purified by silica gel column chromatography to obtain 9.9 g of trans-4-n-propylcyclohexanecarboxylic acid ethyl ester.

(II) 0.73 g (19.1 mmol) of lithium aluminum hydride
Was added to 30 ml of dry ether, and the mixture was refluxed under heating for 1 hour. After cooling to about 10 ° C. in an ice water bath, 5 g (25.5 mmol) of trans-4-n-propylcyclohexanecarboxylic acid ethyl ester dissolved in 30 ml of dry ether was gradually added dropwise. After completion of the dropwise addition, the mixture was stirred at room temperature for 1 hour, and further heated under reflux for 1 hour. This was treated with ethyl acetate and a 6N aqueous hydrochloric acid solution, and then poured into 200 ml of ice water.

After extraction with isopropyl ether, the organic phase was washed successively with water, an aqueous sodium hydroxide solution and water, and dried over magnesium sulfate. After evaporating the solvent, the residue was purified by silica gel column chromatography, and trans-4-
3.5 g of n-propylcyclohexylmethanol was obtained.

(III) 3.4 g (22.4 mmol) of trans-4-n-propylcyclohexylmethanol was dissolved in 20 ml of pyridine.
To this, 5.3 g of p-toluenesulfonic acid chloride dissolved in 20 ml of pyridine was added dropwise while cooling to 5 ° C. or lower in an ice water bath. After stirring at room temperature for 10 hours, the mixture was poured into 200 ml of ice water. After acidification with 6N aqueous hydrochloric acid, extraction with isopropyl ether was performed. The organic phase was repeatedly washed with water until the washing became neutral, and then dried over magnesium sulfate.
The solvent was distilled off to obtain trans-4-n-propylcyclohexylmethyl-p-toluenesulfonate.

(IV) 5-decyl-2-in 40 ml of dimethylformamide
6.3 g of (4'-hydroxyphenyl) pyrimidine (20.2 mm
ol). 1.5 g of 85% potassium hydroxide was added thereto and stirred at 100 ° C. for 1 hour. The transformer-4-n
6.9 g of -propylcyclohexylmethyl-p-toluenesulfonate was added, and the mixture was further stirred at 100 ° C for 4 hours. After the completion of the reaction, this was poured into 200 ml of ice water and extracted with benzene. The organic phase was washed with water and dried over magnesium sulfate. After distilling off the solvent, the residue was purified by silica gel column chromatography, and further recrystallized from a mixed solvent of ethanol / ethyl acetate to obtain Exemplified Compound No. 1-4.

IR (cm ^-1 ): 2920,2840,1608,1584 1428,1258,1164,800 Phase transition temperature (° C) (Sm2 is a smectic phase other than SmA and SmC, unidentified) Examples of specific structural formulas of the compound represented by the general formula (II) are shown below.

The compound represented by the general formula (II) is described in, for example,
61-93170, JP 61-24576, JP 61-129170, JP 6
1-200972, JP-A-61-200973, JP-A-61-215372, JP-A
61-291574. For example, it can be obtained by the following synthetic route.

(R ₃ , R ₄ , and X ₃ are as described above.) The liquid crystal composition of the present invention includes at least one compound represented by the general formula (I) and at least one compound represented by the general formula (II). Seeds and other liquid crystal compounds 1
It can be obtained by mixing at least a seed with an appropriate ratio. Further, the liquid crystal composition according to the present invention is preferably a ferroelectric liquid crystal composition, particularly a ferroelectric chiral smectic liquid crystal composition.

Specific examples of other liquid crystal compounds used in the present invention are shown below.

Each of the liquid crystal compound represented by the general formula (I) and the liquid crystal compound represented by the general formula (II) of the present invention and one or more other liquid crystal compounds described above, or a ferroelectric liquid crystal composition containing the same (Hereinafter abbreviated as a ferroelectric liquid crystal material), the ratio of the liquid crystal compound represented by the general formula (I) or (II) of the present invention is 1 to 300 per 100 parts by weight of the ferroelectric liquid crystal material. More preferably, it is 5 to 100 parts by weight.

Further, when one or both of the liquid crystal compounds represented by the general formulas (I) and (II) of the present invention are used in two or more kinds, the compounding ratio with the ferroelectric liquid crystal material is the same as that of the ferroelectric liquid crystal material described above. One to 500 parts by weight, more preferably 10 to 100 parts by weight, of a mixture of two or more of one or both of the liquid crystal compounds represented by the general formulas (I) and (II) of the present invention per 100 parts by weight. Is preferred.

FIG. 1 is a schematic cross-sectional view of one example of a liquid crystal device having a ferroelectric liquid crystal layer according to the present invention for explaining the configuration of a ferroelectric liquid crystal device.

In FIG. 1, reference numeral 1 denotes a ferroelectric liquid crystal layer, 2 denotes a glass substrate, 3 denotes a transparent electrode, 4 denotes an insulating alignment control layer, 5 denotes a spacer, 6 denotes a lead wire, 7 denotes a power source, 8 denotes a polarizing plate, 9 Indicates a light source.

Each of the two glass substrates 2 is covered with a transparent electrode made of a thin film such as In ₂ O ₃ , SnO ₂ or ITO (Indium-Tin Oxide). Rubbing a polymer thin film such as polyimide on it with gauze or acetate flocking cloth,
An insulating alignment control layer for arranging liquid crystals in the rubbing direction is formed. Also, as an insulating material, for example, silicon nitride,
Hydrogen-containing silicon carbide, silicon oxide, boron nitride, hydrogen-containing boron nitride, cerium oxide,
Aluminum oxide, zirconium oxide, an inorganic material insulating layer such as titanium oxide or magnesium fluoride is formed, and polyvinyl alcohol, polyimide, polyamide imide, polyester imide, polyparaxylene, polyester, polycarbonate, polyvinyl acetal, An organic insulating material such as polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin and photoresist resin is used as an orientation control layer, and an insulating orientation control layer is formed in two layers. It may be a single layer of an inorganic insulating alignment control layer or an organic insulating alignment control layer. If the insulating orientation control layer is inorganic, it can be formed by vapor deposition, etc., and if it is organic, a solution in which an organic insulating material is dissolved, or a precursor solution thereof (solvent 0.1 to 20% by weight, preferably 0.2 to 10% by weight) %), Using a spinner coating method,
It can be formed by applying by dip coating, screen printing, spray coating, roll coating, or the like, and curing under predetermined curing conditions (for example, under heating).

The thickness of the insulating orientation control layer is usually 30 to 1 μm, preferably 30 to 3000, and more preferably 50 to 1000.

The two glass substrates 2 are kept at an arbitrary interval by a spacer 5. For example, there is a method in which silica beads and alumina beads having a predetermined diameter are sandwiched between two glass substrates as spacers, and the periphery is sealed with a sealing material, for example, an epoxy-based adhesive. In addition, a polymer film or a glass fiber may be used as the spacer. A ferroelectric liquid crystal is sealed between the two glass substrates.

The thickness of the ferroelectric liquid crystal layer in which the ferroelectric liquid crystal is sealed is generally 0.5 to 20 μm, preferably 1 to 5 μm.

This ferroelectric liquid crystal has an SmC ^* phase (chiral smectic C phase) in a wide temperature range including room temperature (particularly at a low temperature side), and when used as an element, a driving voltage margin and a driving temperature margin. Is desired to be wide.

In particular, when a device is used, in order to obtain a good uniform orientation and obtain a mono-domain state, the ferroelectric liquid crystal is changed from an isotropic phase to a Ch phase (cholesteric phase) -SmA phase (smectic A phase) -Sm It is desirable to have a phase transition series called ^* phase (chiral smectic C phase).

The transparent electrode 3 is connected to an external power supply 7 by a lead wire.

A polarizing plate 8 is attached to the outside of the glass substrate 2.

 Since FIG. 1 is a transparent type, a light source 9 is provided.

FIG. 2 schematically illustrates an example of a cell for explaining the operation of the ferroelectric liquid crystal element. 21a and 21b are respectively
A substrate (glass plate) coated with a transparent electrode made of a thin film such as In ₂ O ₃ , SnO ₂ or ITO (Indium-Tin Oxide), between which the liquid crystal molecule layer 22 is oriented so as to be perpendicular to the glass surface Liquid crystal of SmC ^* phase or SmH ^* phase is sealed.
A bold line 23 represents a liquid crystal molecule, and the liquid crystal molecule 23 has a dipole moment (P⊥) 24 in a direction perpendicular to the molecule. When a voltage higher than a certain threshold is applied between the electrodes on the substrates 21a and 21b, the helical structure of the liquid crystal molecules 23 is unwound, and the liquid crystal molecules 23 are oriented in such a manner that all dipole moments (P⊥) 24 are directed in the direction of the electric field. Can be changed. The liquid crystal molecules 23 have an elongated shape and exhibit refractive index anisotropy in the major axis direction and the minor axis direction. Therefore, for example, if crossed Nicol polarizers are placed above and below the glass surface, depending on the polarity of the applied voltage, It can be easily understood that the liquid crystal optical modulator has a changed optical characteristic.

The thickness of the liquid crystal cell preferably used in the optical modulation element of the present invention can be made sufficiently thin (for example, 10 μm or less). As such a liquid crystal layer becomes thinner, the helical structure of the liquid crystal molecules is released even in the state where no electric field is applied as shown in FIG. 3, and the dipole moment Pa or Pb thereof is directed upward (34a) or downward (34b). ). An electric field Ea or Eb having a different polarity or more than a certain threshold is applied to such a cell as shown in FIG.
When applied by 31a and 31b, the dipole moment becomes the electric field Ea
Alternatively, the liquid crystal molecules change their directions to upward 34a or downward 34b in accordance with the electric field vector of Eb, and accordingly, the liquid crystal molecules
In the stable state 33a or the second stable state 33b.

As described above, there are two advantages of using such ferroelectricity as the optical modulation element.

The first is that the response speed is extremely fast.
Means that the orientation of liquid crystal molecules has bistability. Second
If the electric field Ea is applied, the liquid crystal molecules are oriented to the first stable state 33a. This state is stable even when the electric field is turned off. When an electric field Eb in the opposite direction is applied, the liquid crystal molecules are brought into the second stable state 33.
The molecule is oriented to b and the direction of the molecule is changed, but it remains in this state even after the electric field is turned off. In addition, as long as the applied electric field Ea or Eb does not exceed a certain threshold value, each is maintained in the previous alignment state.

When a ferroelectric liquid crystal material having such characteristics is sandwiched between a pair of substrates to form a simple matrix display device, for example, JP-A-59-193426, JP-A-59-193427, and JP-A-60-156046. The driving method disclosed in Japanese Unexamined Patent Application Publication No. 60-156047 or Japanese Unexamined Patent Application Publication No. 60-156047 can be applied.

FIG. 4 is a waveform diagram of the driving method used in the embodiment of the present invention. FIG. 5 is a plan view of a ferroelectric liquid crystal panel 51 in which the matrix electrodes used in the present invention are arranged. In the panel 51 of FIG. 5, scanning lines 52 and data lines 53 are wired so as to cross each other, and the scanning lines 52 and data lines 53 at the intersections are arranged.
A ferroelectric liquid crystal is arranged between the two.

Selection information to select the scan waveform S _S of FIG. 4 (A) in which applied to the selected scanning line, the unselected scanning waveform S _N is not selected, I _S is applied to the selected data line waveform (black), I _N represents the non-selection information signal applied to the data line which is not selected (white). Also, (I _S −
S _S ) and (I _N −S _S ) are voltage waveforms applied to the pixels on the selected scanning line. The pixel to which the voltage (I _S −S _S ) is applied takes a black display state, and the voltage (I _S −S _S ) is black. _The pixel to which _N− S _S ) is applied takes a white display state.

FIG. 4B is a time-series waveform when the display shown in FIG. 6 is performed with the driving waveform shown in FIG. 4A.

In the driving example shown in Figure 4, the minimum application time Δt of a single polarity voltage corresponds to the write phase t ₂ time period of a one-line clearing phase t ₁ is applied to a pixel on a selected scanning line 2Δt Is set to

Now, each parameter V _S , of the drive waveform shown in FIG.
The values of V _I and Δt are determined by the switching characteristics of the liquid crystal material used. Figure 7 shows the transmittance change T, then namely V-T characteristic when changing the voltage drive while maintaining a constant bias ratio to be described later (V _S + V _I). Here, Δt = 50 μs, bias ratio V _I / (V _I + V _S ) = 1/3
It is fixed to. The positive side of FIG. 7 is shown in FIG. 4 (I _N
−S _S ) and the waveform indicated by (I _S −S _S ) is applied to the negative side.
Here, V ₁ and V ₃ are called an actual drive threshold voltage and a crosstalk voltage, respectively. However, (V ₂ <V ₁ <V ₃ ) and ΔV = (V ₃ −
V ₁ ) is referred to as a voltage margin, and is a voltage width in which matrix driving is possible. V ₃ may say that the FLC matrix drive generally present. Specifically, FIG. 4 (A) (I _N −
This is a voltage value that causes switching by V _B ′ in the waveform of S _S ). Of course, by increasing the bias ratio
While it is possible to increase the value of V _3, increasing the bias ratio corresponds to a large amplitude of a data signal,
In terms of image quality, flicker increases and contrast lowers, which is not preferable. In our study, a bias ratio of 1/3 to 1/4 was practical. By the way, if the bias ratio is fixed, the voltage margin ΔV strongly depends on the switching characteristics of the liquid crystal material, and it goes without saying that a liquid crystal material having a large ΔV is very advantageous for matrix driving.

At such a certain temperature, two states of “black” and “white” can be written to the selected pixel depending on the two directions of the information signal. And the width (drive voltage margin ΔV) of the applied voltage that can maintain the state of “” are different among liquid crystal materials and are unique. In addition, since the driving margin is deviated by the change in the environmental temperature, in the case of an actual display device, it is necessary to set the driving voltage to an optimal driving voltage for the liquid crystal material and the environmental temperature.

However, when the display area of such a matrix display device is expanded in practice, the difference in the existence environment of the liquid crystal in each pixel (specifically, the difference in the temperature and the cell gap between the electrodes) naturally increases, and the With a liquid crystal having a small voltage margin, a good image cannot be obtained over the entire display area.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

Example 1 A liquid crystalline composition 1-A mixed in the following parts by weight was prepared.

Exemplified compound 1-1,1-
4 were mixed in the following parts by weight, respectively, to obtain a liquid crystal composition 1-B
I got

Next, the optical response was observed using cells prepared from these liquid crystal compositions according to the following procedure.

Two glass plates having a thickness of 1.1 mm were prepared, an ITO film was formed on each of the glass plates, a voltage application electrode was formed, and SiO ₂ was further deposited thereon to form an insulating layer.

A polyimide resin precursor [Toray Co., Ltd. SP-
510] 1.0% dimethylacetamide solution at 3000 rpm.
It was applied for 15 seconds with a m spinner. After film formation, 300 minutes for 60 minutes
A heat condensation calcination treatment was performed at ℃. The film thickness at this time is about
It was 120Å.

The baked film is subjected to a rubbing treatment with an acetate flocking cloth, then washed with an isopropyl alcohol solution, and silica beads having an average particle size of 1.5 μm are sprayed on one of the glass plates. The glass plates were glued together using an adhesive sealant [Rixson Bond (Chisso Corporation)], and dried by heating at 100 ° C. for 60 minutes to form cells. About 1.5μ when measured with a phase plate
m.

The liquid crystal composition 1-B described above was injected into this cell in an isotropic liquid state, and the cell was gradually cooled from the isotropic phase to 25 ° C. at a rate of 20 ° C./h, thereby producing a ferroelectric liquid crystal element.

Using this ferroelectric liquid crystal element, the driving voltage margin ΔV (V
₃ −V ₂ ) was measured. The results are shown below. (Note that Δt
Is set so that V ₂ ≒ 15V) Further, when the voltage was set at the center value of the drive voltage margin at 25 ° C. and the measurement temperature was changed, the temperature difference that can be driven (hereinafter referred to as the drive temperature margin) was ± 3.2 ° C.

The contrast at the time of this driving at 25 ° C. was 10.

Comparative Example 1 Among the liquid crystal compositions 1-B mixed in Example 1, Exemplified Compound No. 1 was added to 1-A without mixing Exemplified Compound No. 2-4.
Liquid crystal composition 1-C in which only -1 was mixed and Exemplified Compound No. 1
A liquid crystal composition 1-D was prepared by mixing only Exemplified Compound No. 2-4 with 1-A without mixing -1.

Instead of using the liquid crystal composition 1-B, the liquid crystal composition 1-A,
Except for injecting 1-C and 1-D into the cell, a ferroelectric liquid crystal element was prepared in exactly the same manner as in Example 1, and the drive voltage margin ΔV was measured. The results are shown below.

Further, the drive temperature margin at 25 ° C. is ± 1−A.
1.9 ° C, ± 2.2 ° C for 1-C and ± 2.4 ° C for 1-D.

As is clear from Example 1 and Comparative Example 1, the ferroelectric liquid crystal element containing the liquid crystalline composition 1-B according to the present invention has a wider driving temperature margin, and changes in environmental temperature and
It has excellent ability to keep images good against variations in the cell gap.

Example 2 To 75 parts by weight of the liquid crystal composition 1-A mixed in Example 1, the following exemplified compounds were mixed in the following parts by weight to obtain a liquid crystal composition 2-B.

Except that this was used, a ferroelectric liquid crystal element was prepared in the same manner as in Example 1, the driving margin was measured in the same manner as in Example 1, and the switching state and the like were observed. The uniform alignment in the liquid crystal element was good, and a monodomain state was obtained. The measurement results are shown below.

Further, the drive temperature margin at 25 ° C. was ± 3.4 ° C. At this temperature, the contrast at the time of this drive was 11.

Comparative Example 2 Among the liquid crystal compositions 2-B mixed in Example 2, Exemplified Compound No. 1 was added to 1-A without mixing Exemplified Compound No. 2-43.
Liquid crystal composition 2-C in which only -17 was mixed and Exemplified Compound No. 1
A liquid crystal composition 2-D was prepared by mixing only Exemplified Compound No. 2-43 with 1-A without mixing -17.

Instead of using the liquid crystal composition 1-B, the liquid crystal composition 1-A,
Except for injecting 2-C and 2-D into the cell, a ferroelectric liquid crystal element was prepared in the same manner as in Example 1, and the driving voltage margin ΔV was measured. The results are shown below.

Further, the drive temperature margin at 25 ° C. is ± 1−A.
1.9 ° C, ± 2.3 ° C for 2-C and ± 2.5 ° C for 2-D.

As is evident from Example 2 and Comparative Example 2, the ferroelectric liquid crystal element containing the liquid crystal composition 2-B according to the present invention has a wider driving temperature margin, changes in environmental temperature, and variations in cell gap. Excellent ability to keep images good.

Example 3 A liquid crystal composition 3-A mixed in the following parts by weight was prepared.

The exemplary compound 1-1,2-
4,2-16 were mixed in the following parts by weight to obtain a liquid crystal composition 3-B.

A ferroelectric liquid crystal element was prepared in the same manner as in Example 1 except that the liquid crystal composition 1-B was replaced with the liquid crystal composition 3-B, and the drive voltage margin ΔV was measured in the same manner as in Example 1. Then, the switching state and the like were observed. The uniform alignment in the liquid crystal element was good, and a monodomain state was obtained. The measurement results are shown below.

Further, the drive temperature margin at 25 ° C. was ± 3.4 ° C. The contrast at the time of this driving at this temperature was 10.

Comparative Example 3 Among the liquid crystal compositions 3-B mixed in Example 3, only Example Compound No. 1-1 was mixed with 3-A without mixing Example Compound Nos. 2-4 and 2-16. Without mixing the liquid crystal composition 3-C and the exemplary compound No. 1-1, the exemplary compound No.
A liquid crystal composition 3-D in which only −4 and 2-16 were mixed was prepared.

Instead of using the liquid crystal composition 1-B, the liquid crystal composition 3-A,
Except for injecting 3-C and 3-D into the cell, a ferroelectric liquid crystal element was prepared in the same manner as in Example 1, and the drive voltage margin ΔV was measured. The results are shown below.

Further, the drive temperature margin at 25 ° C. is ± A at 3-A.
It was ± 2.6 ° C at 2.4 ° C and 3-C and ± 2.8 ° C at 3-D.

As is clear from Example 3 and Comparative Example 3, the driving margin of the ferroelectric liquid crystal device containing the liquid crystal composition 3-B according to the present invention is wider than that of the ferroelectric liquid crystal device according to the present invention. And the ability to keep images good.

Example 4 To 75 parts by weight of the liquid crystal composition 3-A mixed in Example 3, the following exemplified compounds were mixed in the following parts by weight to obtain a liquid crystal composition 4-B.

Except that this was used, a ferroelectric liquid crystal element was prepared in the same manner as in Example 1, the driving margin was measured in the same manner as in Example 1, and the switching state and the like were observed. The uniform alignment in the liquid crystal element was good, and a monodomain state was obtained. The measurement results are shown below.

Further, the drive temperature margin at 25 ° C. was ± 3.6 ° C. At this temperature, the contrast at the time of this drive was 11.

Comparative Example 4 Among the liquid crystal compositions 4-B mixed in Example 4, only the exemplified compounds No. 1-24 were mixed with the 3-A without mixing the exemplified compounds No. 2-56 and 2-43. Without mixing the liquid crystal composition 4-C and the exemplary compound No. 1-24, the compound of the exemplary compound No. 2
A liquid crystal composition 4-D in which only −56, 2-43 was mixed was prepared.

Instead of using the liquid crystal composition 1-B, the liquid crystal composition 3-A,
Except for injecting 4-C and 4-D into the cell, a ferroelectric liquid crystal element was prepared in the same manner as in Example 1, and the drive voltage margin ΔV was measured. The results are shown below.

Further, the drive temperature margin at 25 ° C. is ± A at 3-A.
It was ± 2.8 ° C at 2.4 ° C and 4-C, and ± 2.6 ° C at 4-D.

As is clear from Example 4 and Comparative Example 4, the driving voltage and the temperature margin of the ferroelectric liquid crystal element containing the liquid crystal composition 4-B according to the present invention were wider, and the ambient temperature and change, and the cell gap were better. It has excellent ability to keep images good against variations in the image quality.

Example 5 A liquid crystal composition 5-A mixed in the following parts by weight was prepared.

With respect to this liquid crystal composition 5-A, exemplary compound 1-1,2-
4 were mixed in the following parts by weight, respectively, to obtain a liquid crystal composition 5-B.
I got

A ferroelectric liquid crystal element was prepared in the same manner as in Example 1 except that the liquid crystal composition 1-B was replaced with the liquid crystal composition 5-B, and the driving voltage margin ΔV was measured in the same manner as in Example 1. Then, the switching state and the like were observed. The uniform alignment in the liquid crystal element was good, and a monodomain state was obtained. The measurement results are shown below.

Further, the drive temperature margin at 25 ° C. was ± 3.2 ° C. The contrast at the time of this driving at this temperature was 10.

Comparative Example 5 Among the liquid crystal compositions 5-B mixed in Example 5, Exemplified Compound No. 1 was added to 5-A without mixing Exemplified Compound No. 2-4.
Liquid crystal composition 5-C in which only -5 was mixed and Exemplified Compound No. 1
A liquid crystal composition 5-D was prepared by mixing only exemplary compound No. 2-4 with 5-A without mixing -5.

Instead of using the liquid crystal composition 1-B, the liquid crystal composition 5-A,
Except for injecting 5-C and 5-D into the cell, a ferroelectric liquid crystal element was prepared in the same manner as in Example 1, and the drive voltage margin ΔV was measured. The results are shown below.

Further, the driving temperature margin at 25 ° C.
It was ± 2.3 ° C at 2.5 ° C and 5-C, and ± 2.5 ° C at 5-D.

As is clear from Example 5 and Comparative Example 5, the driving margin of the ferroelectric liquid crystal device containing the liquid crystal composition 5-B according to the present invention is wider than that of the ferroelectric liquid crystal device of the present invention. And the ability to keep images good.

Example 6 To 75 parts by weight of the liquid crystal composition 5-A mixed in Example 5, the following exemplified compounds were mixed in the following parts by weight to obtain a liquid crystal composition 6-B.

Except that this was used, a ferroelectric liquid crystal element was prepared in the same manner as in Example 1, the driving margin was measured in the same manner as in Example 1, and the switching state and the like were observed. The uniform alignment in the liquid crystal element was good, and a monodomain state was obtained. The measurement results are shown below.

Further, the drive temperature margin at 25 ° C. was ± 3.6 ° C. At this temperature, the contrast at the time of this drive was 11.

Comparative Example 6 Among the liquid crystal compositions 6-B mixed in Example 6, Exemplified Compound No. 1 was added to 5-A without mixing Exemplified Compound No. 2-43.
Liquid crystal composition 6-C in which only -3 was mixed and Exemplified Compound No. 1
A liquid crystal composition 6-D was prepared by mixing only exemplary compound No. 2-43 with 5-A without mixing -3.

Instead of using the liquid crystal composition 1-B, the liquid crystal composition 5-A,
Except for injecting 5-C and 5-D into the cell, a ferroelectric liquid crystal element was prepared in the same manner as in Example 1, and the drive voltage margin ΔV was measured. The results are shown below.

Further, the driving temperature margin at 25 ° C.
2.2 ° C, ± 2.4 ° C for 6-C, and ± 2.8 ° C for 6-D.

As is clear from Example 6 and Comparative Example 6, the driving margin of the ferroelectric liquid crystal element containing the liquid crystal composition 6-B according to the present invention is wider, and the change in the environmental temperature and the variation in the cell gap are reduced. On the other hand, it has excellent ability to keep images good.

Example 7 Liquid crystal composition 1-A, 1 used in Example 1 and Comparative Example 1
A ferroelectric liquid crystal device was prepared in exactly the same manner as in Example 1 except that the alignment control layer was formed only of polyimide resin without using SiO ₂ for -B, 1-C, and 1-D. The drive voltage margin was measured in the same manner as in Example 1. The results are shown below.

Further, the drive temperature margin at 25 ° C was 1-B ± 3.2 ° C 1-C ± 2.2 ° C 1-D ± 2.4 ° C 1-A ± 2.0 ° C.

As is clear from Example 7, even when the element configuration is changed, the device containing the ferroelectric liquid crystal composition 1-B according to the present invention has the same properties as those of Example 1 as compared with the devices containing other liquid crystal compositions. The drive margin is wide, and it is excellent in the ability to maintain an image satisfactorily against changes in environmental temperature and variations in cell gap.

Examples 8 to 15 Instead of the exemplified compounds and the liquid crystalline compositions used in Examples 1, 3, and 5, the exemplified compounds and the liquid crystalline compositions shown in Table 1 were used in parts by weight, and 8-B to 15-B were used. Was obtained.
Except that these were used, a ferroelectric liquid crystal element was prepared in the same manner as in Example 1, and the temperature was adjusted to 25 ° C. in the same manner as in Example 1.
Was measured, and a switching state and the like were observed.

The uniform alignment in each of the prepared liquid crystal elements was good, and a monodomain state was obtained.

 Table 1 shows the measurement results.

As is clear from Examples 8 to 15, the ferroelectric liquid crystal device containing the liquid crystalline compositions 8-B to 15-B according to the present invention has a wide driving margin, and is resistant to changes in environmental temperature and variations in cell gap. Excellent ability to keep images good.

[Effects of the Invention] The device containing the ferroelectric liquid crystal composition of the present invention has good switching characteristics, a large driving voltage margin, and all pixels are good even if there is some temperature variation on the display area of the device. Thus, a liquid crystal element having a wide driving temperature margin capable of matrix driving can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an example of a liquid crystal display device using a ferroelectric liquid crystal. FIGS. 2 and 3 schematically show an example of an element cell for explaining the operation of the ferroelectric liquid crystal device. FIG. 4 is a perspective view, FIG. 4 is a waveform diagram of the driving method used in the embodiment, FIG. 5 is a plan view of a ferroelectric liquid crystal panel in which matrix electrodes are arranged, and FIG. FIG. 7 is a schematic diagram of a display pattern when actual driving is performed with a series driving waveform. FIG. 7 is a VT characteristic diagram showing a change in transmittance when a driving voltage is changed. In FIG. ... ferroelectric liquid crystal layer 2 ... glass substrate 3 ... transparent electrode 4 ... insulating alignment control layer 5 ... spacer 6 ... lead wire 7 ... power supply 8 ... polarizing plate 9 ... light source Io ... incident In FIG. 2, 21a... Substrate 21b... Substrate 22... Ferroelectric liquid crystal layer 23. In FIG. 3, 31a... Voltage applying means 31b... Voltage applying means 33a... First stable state 33b... Second stable state 34a. Dipole moment 34b …… Downward dipole moment Ea …… Upward electric field Eb …… Downward electric field

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Iwaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Makoto Mori 3-30-2 Shimomaruko, Ota-ku, Tokyo K Within Canon Inc. (56) References JP-A-2-24386 (JP, A)

Claims (2)

(57) [Claims] 1. A compound represented by the following general formula (I) (Wherein, R ₁ is a C ₁ -C ₁₈ linear or branched alkyl group which may be substituted by fluorine or an alkoxy group, and R ₂ is a C ₁ -C ₁₂ linear alkyl group. X ₁ is a single bond, -O-, And either. Is one of ) And at least one compound represented by the following general formula (II) (Wherein, R ₃ and R ₄ are C _{1 to} C ₁₈ linear or branched alkyl groups, at least one of which is optically active. X ₂ , X ₃
Is a single bond, -O-, Is one of A) a ferroelectric chiral smectic liquid crystal composition comprising at least one of the following: 2. The following general formula (I) (Wherein, R ₁ is a C ₁ -C ₁₈ linear or branched alkyl group optionally substituted by fluorine or an alkoxy group, and R ₂ is a C ₁ -C ₁₂ linear alkyl group. X ₁ is a single bond, -O-, And either. Is one of ) And at least one compound represented by the following general formula (II) (Wherein, R ₃ and R ₄ are C _{1 to} C ₁₈ linear or branched alkyl groups, at least one of which is optically active. X ₂ , X ₃
Is a single bond, -O-, Is one of A liquid crystal device comprising a ferroelectric chiral smectic liquid crystal composition containing at least one of the following: