JP2791039B2 - 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 occur. It is an inevitable drawback. Such a phenomenon is caused by a liquid crystal having no bistability (the liquid crystal molecules are horizontally aligned with respect to the electrode surface in a stable state, and are vertically aligned only when an electric field is effectively applied). This is essentially an unavoidable problem that arises when driving is performed using the time accumulation effect (that is, repeated scanning). 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. Patent No. 4367924). As the bistable liquid crystal, a ferroelectric liquid crystal having a chiral smectic C phase (SmC ^* ) or an H phase (SmH ^* ) is generally used. 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 of a single polarity voltage △ t corresponds to the write phase t ₂ time, the time a one-line clearing phase t ₁ is applied to a pixel on a selected scanning line It is set to 2 △ t.

Now, each parameter V _S , V _I ,
The value of Δt is determined by the switching characteristics of the liquid crystal material used.

FIG. 7 shows a change in the transmittance T, that is, a VT characteristic when the drive voltage (V _S + V _I ) is changed while a bias ratio described later is kept constant. Here, Δt = 50μ
s and the bias ratio V _I / (V _I + V _S ) = 1/3.
The positive side of FIG. 7 is (I _N −S _S ) shown in FIG. 4, and the negative side is (I _{S −}
−S _S ) is applied. 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 ) or ΔV = (V ₃ −V ₁ ) is called a voltage margin, which is a voltage width in which matrix driving is possible. V ₃ is FL
It can be said that there is generally a C matrix drive. 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, which means that increasing the bias ratio to increase the amplitude of the information signal, the picture quality to flickering increases, in contrast It is not preferable because it causes a decrease. 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 △ 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 △ V) capable of maintaining the state of “white”
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 cell gap difference between the temperature and the voltage) 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 the following general formula (I) (Wherein, R ₁ is a C ₁ -C ₁₈ linear or branched alkyl group, R ₂ is a C ₁ -C ₁₄ linear or branched alkyl group, X ₁ , X ₂ is a single bond, -O-, It is. m represents 0 to 7, and n represents 0 or 1. ) And at least one compound represented by the following general formula (II) (Wherein, R ₃ and R ₄ are a C _{1 to} C ₁₈ linear or branched alkyl group optionally substituted by an alkoxy group, and X ₃ and X ₄ are a single bond, —O—, And Y is —CH ₂ O— or —OCH ₂ —. p and q are 1
Or 2. A ferroelectric chiral smectic liquid crystal composition characterized by containing at least one compound represented by the formula (1), and a liquid crystal element comprising the liquid crystal composition disposed between a pair of electrode substrates. It is.

Among the compounds represented by the above-mentioned general formula (I), preferred examples of the compound include X ₁ and X ₂ represented by the following (Ii) to (Ii).
The compound which is v) can be mentioned.

Further, more preferable examples of R ₁ and R ₂ include a linear alkyl group having 1 to 14 carbon atoms.

Among the compounds represented by the general formula (II), preferred examples of the compound include compounds represented by the following formulas (II-a) to (II-f).

Further, in the above formulas (II-a) to (II-f),
Preferred examples of X ₃ and X ₄ include (II-i) to (II-viii)
Can be mentioned.

Further, preferred examples of R ₃ and R _{4 in} the above formulas (II-a) to (II-f) are (II-ix) to (II-xii).
i) can be mentioned.

(II-ix) R ₃ is an n-alkyl group, and R ₄ is (P is 0 to 7, R ₅ is a linear or branched alkyl group) (II-x) R ₃ is R ₄ (P and q are 0 to 7; R ₅ and R ₆ are linear or branched alkyl groups) (II-xi) R ₃ is an n-alkyl group and R ₄ is (R is 1 to 12) (II-xii) R ₃ is an n-alkyl group, and R ₄ is (S is 0 to 7, t is 0 or 1, R ₇ is a linear or branched alkyl group) Examples of specific structural formulas of the liquid crystal compound represented by the general formula (I) are shown below. .

A typical synthesis example of the compound represented by the formula (I) is shown below.

Synthesis Example 1 (Synthesis of Compound No. 1-20) 5-Methoxyhexanol 1.0 dissolved in 5 ml of pyridine
1.83 g (9.6 mmol) of p-toluenesulfonic acid chloride dissolved in 6 ml (8.0 mmol) of pyridine in 5 ml was added dropwise at 5 ° C or lower in an ice water bath. After stirring at room temperature for 6 hours, the reaction mixture was cooled with cold water.
Injected into 100 ml. After acidification with 6N hydrochloric acid, the mixture was extracted with isopropyl ether. The organic layer was washed with water, dried over anhydrous magnesium sulfate, and then the solvent was distilled off to obtain 5-methoxyhexyl-p-toluenesulfonate.

To 10 ml of dimethylformamide was added 5-decyl-2- (p-
2.0 g (6.41 mmol) of hydroxyphenyl) pyrimidine and 0.61 g of potassium hydroxide were added, and the mixture was stirred at 100 ° C. for 40 minutes. To this, the previously obtained 5-methoxyhexyl-p-toluenesulfonate was added, and the mixture was heated and stirred at 100 ° C for 4 hours. After the completion of the reaction, the reaction mixture was poured into 100 ml of cold water and extracted with benzene. After washing with water, the extract was dried over anhydrous magnesium sulfate and the solvent was distilled off to obtain a pale yellow oil. Column chromatography (silica gel-ethyl acetate / benzene = 1 /
After purification according to 9), recrystallization from hexane gave 1.35 g of 5-decyl-2- {4- (5'-methoxyhexyloxy) phenyl} pyrimidine (Exemplary Compound No. 21).

Synthesis Example 2 (Synthesis of Compound No. 1-25) 2.04 g of 6-pentyloxyheptanol was added to 8 ml of pyridine
And cooled with ice, and 2.26 g of tosyl chloride dissolved in 5 ml of pyridine was gradually added dropwise (5 ° C. or lower, 7 minutes).
Thereafter, the mixture was stirred at room temperature for 5 hours.

The reaction mixture was poured into 150 ml of ice water, and the pH was adjusted to 3 with a 6N hydrochloric acid aqueous solution.
After adjusting to a degree, the mixture was extracted with ethyl acetate. After washing with water and drying over anhydrous magnesium sulfate, the solvent was distilled off to obtain 2.98 g of (6-pentyloxyheptyl) p-toluenesulfonate.

3.12 g of 5-n-decyl-2- (4-hydroxyphenyl) pyrimidine and 0.53 g of potassium hydroxide were dissolved in 14 ml of dimethylformamide, and the mixture was stirred with heating at 100 ° C. for 3 hours, and then dissolved in (6-pentyloxyheptyl) p- 2.98 g of toluene sulfonate was added, and the mixture was heated and stirred at 100 ° C. for 5 hours.

The reaction mixture was poured into 200 ml of ice water, and the pH was adjusted to 3 with a 6N hydrochloric acid aqueous solution.
After reducing the volume, the mixture was extracted with benzene. Wash this,
After drying over anhydrous magnesium sulfate, the solvent was distilled off to obtain 4.71 g of a crude product. This was purified by silica gel column chromatography (n-hexane / ethyl acetate = 10/2) and further recrystallized from hexane to give 5-n-decyl-2- [4- (6
-Pentyloxyheptyloxy) phenyl] pyrimidine 1.56 g.

IR (cm ^-1 ) 2924,2852,1610,1586,1472,1436,1254,1168,1096,798 Compounds other than the synthesis examples can be obtained by the following synthesis routes A and B.

(In the above, R ₁ , R ₂ , X ₁ , m, and n are as described above.) Examples of specific structural formulas of the compound represented by the general formula (II) are shown below.

The compound represented by the general formula (I) is described in, for example,
60-144957 (1985) and JP-A-61-63633 (1986). Representative synthesis examples are shown below.

Synthesis Example 1 (Synthesis of Compound No. 2-54) The following alcohol derivative in a 30 ml eggplant flask 1.0 g (4.81 mmol) was added, 3 ml of thionyl chloride was added under cooling, the temperature was raised to room temperature with stirring, a condenser was attached, and the mixture was heated and refluxed in an external bath at 70 ° C to 80 ° C for 4 hours.
After the reaction, excess thionyl chloride was distilled off to obtain a chloride. This was dissolved in 15 ml of toluene.

Next, 0.33 g of 60% oil-based hydrogenated sodium hydride was placed in a 200 ml three-necked flask, washed several times with dry n-hexane, and then 1.52 g (4.81 mmol) of the following phenol derivative: Was added dropwise at room temperature, and 20 ml of DMSO was further added thereto and stirred for 1 hour. To this, the above-mentioned toluene solution of chloride is slowly added dropwise, and after the addition is completed, the solution is further added at room temperature to 16 mL.
Stirring was continued for hours.

After the completion of the reaction, the mixture was poured into about 200 ml of ice water, the organic layer was separated, and the aqueous layer was extracted twice with 50 ml of benzene. The organic layer was washed twice with a 5% hydrochloric acid aqueous solution together with the previously separated organic layer. , And once with a 5% aqueous NaOH solution, and then the organic layer was washed with ion-exchanged water until the pH value of the aqueous layer became neutral.

Take out the organic layer and dry using magnesium sulfate,
The solvent was distilled off to obtain a crude product. This was purified by silica gel column chromatography using developing solution n-hexane / dichloromethane, 3/10.

The crystals obtained by distilling off the solvent were recrystallized using n-hexane to obtain a purified product. Furthermore, drying under reduced pressure was performed at room temperature to obtain 0.69 g of the final purified product. The yield was 28.5%.

Elemental analysis value (wt%) Calculated value for CHN 78.33 8.57 0.00 Measured value 78.96 8.69 0.02 Synthesis Example 2 (Compound (Synthesis of No. 2-68) The following alcohol derivative in a 30 ml eggplant flask 1.25 g (4.01 mmol) was added, 4 ml of thionyl chloride was added under cooling, the temperature was raised to room temperature with stirring, a cooling tube was attached, and the mixture was heated and refluxed in an external bath at 70 to 80 ° C. for 4 hours.
After the reaction, excess thionyl chloride was distilled off to obtain a chloride. This was dissolved in 15 ml of toluene.

Next, 0.31 g of 60% oily sodium hydride was placed in a 200 ml three-necked flask, washed several times with dry n-hexane, and then 0.79 g (4.01 mmol) of the following phenol derivative: Was added dropwise at room temperature, and 20 ml of DMSO was further added thereto and stirred for 1 hour. To this, the above-mentioned toluene solution of chloride is slowly added dropwise, and after the addition is completed, the solution is further added at room temperature to 16 mL.
Stirring was continued for hours.

After the reaction was completed, the reaction mixture was poured into about 200 ml of ice water, the organic layer was separated, and the aqueous layer was extracted twice with 50 ml of benzene. After washing once with exchanged water and once with a 5% aqueous NaOH solution, the organic layer was washed with ion-exchanged water until the pH value of the aqueous layer became neutral.

Take out the organic layer and dry using magnesium sulfate,
The solvent was distilled off to obtain a crude product. This was purified by silica gel column chromatography using developing solution n-hexane / dichloromethane, 3/10.

The crystals obtained by distilling off the solvent were recrystallized using n-hexane to obtain a purified product. Furthermore, drying under reduced pressure was performed at room temperature to obtain 0.51 g of a final purified target product. The yield was 26.0%.

CHN analysis value (wt%) Calculated value of CHN 78.33 8.63 0.00 Logical value 78.62 8.86 0.02 IR spectrum 2975,2925,2850,1610,1510,1470,1380,1
295,1280,1240,1220,1130,1020,1000,810 cm ^-1 The liquid crystal composition of the present invention comprises at least one compound represented by the general formula (I) and a compound represented by the general formula (II) And at least one other liquid crystal compound 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 5 to 100 parts by weight
It is preferable to use 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. 1 to 500 parts by weight, more preferably 10 to 100 parts by weight, per 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. 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.

The two glass substrates 2 are each coated with a transparent electrode made of a thin film such as In ₂ O ₃ , SnO ₂ or ITO (Indium-Tin Oxide). On top of that, a thin film of a polymer such as polyimide is rubbed with a gauze, an acetate flocking cloth or the like to form an insulating alignment control layer for arranging liquid crystals in the rubbing direction. Examples of the insulating material include silicon nitride, silicon carbide containing hydrogen, silicon oxide, boron nitride, boron nitride containing hydrogen, cerium oxide, aluminum oxide, zirconium oxide, titanium oxide, and fluoride. Form an inorganic insulating layer such as magnesium,
Polyvinyl alcohol, polyimide, polyamide imide, polyester imide, polyparaxylene, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide,
An organic insulating material such as polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin, and photoresist resin may be used as an orientation control layer, and an insulating orientation control layer may be formed as two layers, or an inorganic material insulating orientation It may be a control layer or a single layer of an organic substance insulating orientation 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 thereof is sealed with a sealing material, for example, an epoxy 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.

Further, the 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. A wide margin is desired.

In particular, in order to obtain a good uniform compounding property and obtain a monodomain state in the case of a device, the ferroelectric liquid crystal is changed from an isotropic phase to a Ch phase (cholesteric phase) -SmA phase (smectic A phase) -SmC ^*. It is desirable to have a phase transition series called a 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 was oriented so as to be perpendicular to the glass surface Liquid crystal of SmC ^* phase or SmH ^* phase is enclosed. 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 shown in FIG. 3, as the liquid crystal layer becomes thinner, the helical structure of the liquid crystal molecules is released even when no electric field is applied, and the dipole moment Pa or Pb of the liquid crystal layer is 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 of a single polarity voltage △ t corresponds to the write phase t ₂ time, the time a one-line clearing phase t ₁ is applied to a pixel on a selected scanning line It is set to 2 △ t.

Now, each parameter V _S , V _I ,
The value of Δt is 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 and the bias ratio V _I / (V _I + V _S ) = 1/3 are fixed. The positive side of FIG. 7 is shown in FIG. 4 (I _N -S _S )
On the negative side, a waveform shown by (I _S −S _S ) is applied. 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, 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 Is undesirably caused. 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 (driving voltage margin ΔV) of the applied voltage capable of maintaining the state of “” differ between 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 crystal composition 1 was prepared by mixing the following exemplified compounds in the following parts by weight.
-A was created.

The exemplary compound 1-5,2-
6 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 are glued together using an adhesive sealant [Rixon Bond (Chitsuso Co., Ltd.)] so that they are parallel to each other.
The cells were dried by heating at 100 ° C for minutes. When the cell thickness of this cell was measured with a Beret phase plate, about 1.5
μm.

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 drive voltage margin ΔV (V
₃ -V ₁₎ was measured. The results are shown below (where Δt is V
₂ Set to 15V).

Further, when the voltage was set at the center value of the drive voltage margin at 25 ° C. and the measured temperature was changed, the drivable temperature difference (hereinafter referred to as the drive temperature margin) was ± 3.4 ° C.

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

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

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 driving voltage margin ΔV was measured. The results are shown below.

Further, the drive temperature margin at 25 ° C. is ± 1−A.
2.2 ° C, ± 2.6 ° C for 1-C and ± 2.5 ° C for 1-D.

As is clear from Example 1 and Comparative Example 1, the driving margin of the ferroelectric liquid crystal element containing the liquid crystal composition 1-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 2 A liquid crystal composition 2 was prepared by mixing the following exemplified compounds in the following parts by weight.
-A was created.

The exemplary compound 1-5,2-
6 were mixed in the following parts by weight, respectively, to obtain a liquid crystal composition 2-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 2-B, and the driving voltage margin ΔV was reduced in the same manner as in Example 1. It measured and observed the switching state etc. The uniform alignment in the liquid crystal element was good, and a monodomain state was obtained. The measurement results are shown below.

Furthermore, the drive temperature margin at 25 ° C is ± 3.6 ° C
Met. The contrast at the time of this driving at this temperature was 9.

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

Instead of using the liquid crystal composition 1-B, the liquid crystal composition 2-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 margins at 25 ° C. were ± 2.5 ° C. for 2-A, ± 2.8 ° C. for 2-C, and ± 2.5 ° C. for 2-D.

As is clear from Example 2 and Comparative Example 2, the ferroelectric liquid crystal device containing the liquid crystal compound 2-B according to the present invention has a wider driving margin, and is less susceptible to changes in environmental temperature and variations in cell gap. On the other hand, it has excellent ability to keep images good.

Example 3 The liquid crystal composition 2-A used in Example 2 was mixed with the following exemplified compounds in the following parts by weight to obtain a liquid crystal composition 3-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. The contrast at the time of this driving at this temperature was 8.

Comparative Example 3 Among the liquid crystal compositions 3-B used in Example 3, Exemplified Compound No. 1 was used for 2-A without mixing Exemplified Compound No. 2-14.
Liquid crystal composition 3-C in which only -20 was mixed and Exemplified Compound No. 1
A liquid crystal composition 3-D was prepared by mixing only Exemplified Compound No. 2-14 with 2-A without mixing -20.

Instead of using the liquid crystal composition 1-B, the liquid crystal composition 2-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 driving voltage margin ΔV was measured. The results are shown below.

Further, the drive temperature margin at 25 ° C.
2.5 ° C, ± 2.5 ° C for 3-C and ± 2.7 ° C for 3-D.

As is clear from Example 3 and Comparative Example 2, the driving margin of the ferroelectric liquid crystal element containing the liquid crystal composition 3-B according to the present invention is wider, and the driving margin is more affected by changes in environmental temperature and variations in cell gap. On the other hand, it has excellent ability to keep images good.

Example 4 The liquid crystal composition 2-A used in Example 2 was mixed with the following exemplified compounds 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 used in Example 4, Exemplified Compound No. 1 was used for 2-A without mixing Exemplified Compound No. 2-18.
Liquid crystal composition 4-C mixed with -10 only and Exemplified Compound No. 1
A liquid crystal composition 4-D was prepared by mixing only Exemplified Compound No. 2-18 with 2-A without mixing -10.

Instead of using the liquid crystal composition 1-B, the liquid crystal composition 2-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 driving voltage margin ΔV was measured. The results are shown below.

Further, the driving temperature margin at 25 ° C. is ± 2 ± A.
2.3 ° C, ± 2.7 ° C for 4-C and ± 2.5 ° C for 4-D.

As is clear from Example 4 and Comparative Example 4, the driving margin of the ferroelectric liquid crystal device containing the liquid crystal composition 4-B according to the present invention was wider, and the variation in the environmental temperature and the variation in the cell gap were reduced. On the other hand, it has excellent ability to keep images good.

Example 5 The following exemplified compounds were mixed in the following parts by weight to prepare a liquid crystal composition 5-A.

Exemplified compound 1-20,2- with respect to this liquid crystal composition 5-A
14 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 reduced in the same manner as in Example 1. It measured and observed the switching state etc. The uniform alignment in the liquid crystal element was good, and a monodomain state was obtained. The measurement results are shown below.

Furthermore, the drive temperature margin at 25 ° C is ± 2.9 ° C
Met. The contrast at the time of this driving at this temperature was 9.

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. 2-14.
Liquid crystal composition 5-C in which only -20 was mixed with Exemplified Compound N
Example Compound No. 2-1 to 5-A without mixing o.1-20
A liquid crystal composition 5-D in which only 4 was mixed was prepared.

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 driving voltage margin ΔV was measured. The results are shown below.

Further, the drive temperature margins at 25 ° C. were ± 1.9 ° C. for 5-A, ± 2.1 ° C. for 5-C, and ± 2.2 ° C. for 5-D.

As is clear from Example 5 and Comparative Example 5, the driving margin is wide in the direction of the ferroelectric liquid crystal device containing the liquid crystal composition 5-B according to the present invention. On the other hand, it has excellent ability to keep images good.

Example 6 The liquid crystal composition 5-A used in Example 5 was mixed with the following exemplified compounds 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 ± 2.8 ° C. The contrast at the time of this driving at this temperature was 10.

Comparative Example 6 In the liquid crystal composition 6-B used in Example 6, the compound No. 1 was added to the compound 5-A without mixing the compound No. 2-18.
Liquid crystal composition 6-C, which is a mixture of Ex.
A liquid crystal composition 6-D was prepared by mixing only Exemplified Compound No. 2-18 with 5-A without mixing -10.

Instead of using the liquid crystal composition 1-B, the liquid crystal composition 5-A,
Except for injecting 6-C and 6-D into the cell, a ferroelectric liquid crystal device 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 driving temperature margin at 25 ° C.
1.9 ° C, ± 2.1 ° C for 6-C, and ± 2.1 ° 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 5-B, 5 used in Example 5 and Comparative Example 5
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 -C, 5-D and 5-A. 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: 5-B ± 3.1 ° C. 5-C ± 2.2 ° C. 5-D ± 2.3 ° C. 5-A ± 2.0 ° C.

As is clear from Example 7, even when the element configuration is changed, the element containing the ferroelectric liquid crystal composition 5-B according to the present invention is similar to Example 5 in comparison with elements 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 13 Instead of the exemplified compounds and liquid crystalline compositions used in Examples 1, 2, and 5, the exemplified compounds and liquid crystalline compositions shown in Table 1 were used in parts by weight, and 8-B to 13-B 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 13, the driving margin of the ferroelectric liquid crystal device containing the liquid crystal compositions 8-B to 13-B according to the present invention is wide, and the driving margin for the ferroelectric liquid crystal composition is varied with respect to the change of the environmental temperature and the variation of the cell gap. And the ability to keep images good.

〔The invention's effect〕

The device containing the ferroelectric liquid crystal composition of the present invention has a good switching characteristic, a large driving voltage margin, and a driving temperature at which all the pixels can be satisfactorily driven in a matrix even if there is some temperature variation on the display area of the device. A liquid crystal element with a wide margin 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, and 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. 6 is FIG. FIG. 7 is a schematic diagram of a display pattern when actual driving is performed with a time-series driving waveform. FIG. 7 shows a change in transmittance when a driving voltage is changed, that is, a VT characteristic diagram. DESCRIPTION OF SYMBOLS 1 ... 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 I _O ... Incident light I. transmitted light. In FIG. 2, 21a... Substrate 21b... Substrate 22... 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. (58) Field surveyed (Int.Cl. ⁶ , DB name) C09K 19/42

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, R ₂ is a C ₁ -C ₁₄ linear or branched alkyl group, X ₁ , X ₂ is a single bond, -O-, It is. m represents 0 to 7, and n represents 0 or 1. ) And at least one compound represented by the following general formula (II) (Wherein, R ₃ and R ₄ are a C _{1 to} C ₁₈ linear or branched alkyl group optionally substituted by an alkoxy group, and X ₃ and X ₄ are a single bond, —O—, And Y is —CH ₂ O— or —OCH ₂ —. p and q are 1
Or 2. A ferroelectric chiral smectic liquid crystal composition comprising at least one compound represented by the following formula: 2. The following general formula (I) (Wherein, R ₁ is a C ₁ -C ₁₈ linear or branched alkyl group, R ₂ is a C ₁ -C ₁₄ linear or branched alkyl group, X ₁ , X ₂ is a single bond, -O-, It is. m represents 0 to 7, and n represents 0 or 1. ) And at least one compound represented by the following general formula (II) (Wherein, R ₃ and R ₄ are a C _{1 to} C ₁₈ linear or branched alkyl group which may be substituted by an alkoxy group;
₃ , X ₄ is a single bond, -O-, And Y is —CH ₂ O— or —OCH ₂ —. p and q are 1
Or 2. A liquid crystal device comprising a ferroelectric chiral smectic liquid crystal composition containing at least one compound represented by the following formula: