JPS6167828A - chiral smectic liquid crystal element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal element 1c used in a liquid crystal display element, a liquid crystal-light shutter, etc., and more specifically, a liquid crystal element 1c with improved display and driving characteristics by improving the initial alignment state of liquid crystal molecules. It is related to the element.

Conventionally, liquid crystal display elements display images or information by configuring a scanning electrode group and a signal electrode group in a matrix, and filling a liquid crystal compound between the electrodes to form a large number of pixels.
well known.

The driving method for this display element is time-division driving, in which an address signal is selectively and periodically applied to a group of scanning electrodes, and a predetermined information signal is selectively applied in parallel to a group of signal electrodes in synchronization with the address signal. However, this display element and its driving method have major and fatal drawbacks as described below.

In other words, it is unwise to increase the pixel density or enlarge the screen. Among conventional liquid crystals, most of them are used practically as display elements because of their relatively high response speed and low power consumption.
'li @tlPhysios Letters V
o, 18.44 (1971.

2.15), P127-128 “Voltage”
-DeprmentOptical Activity
of a Twisted NematicLiqu
TI (twist
This type of liquid crystal forms a structure (helical structure) in which nematic liquid crystal molecules with positive dielectric anisotropy are arranged in the thickness direction of the liquid crystal layer in the absence of an electric field. However, a structure is formed in which the liquid crystal molecules are arranged in parallel on both electrode surfaces. - When an electric field is applied, nematic liquid crystals with positive dielectric anisotropy align in the direction of the electric field, resulting in optical modulation. When a display element is constructed with a matrix electrode structure using this type of liquid crystal17, in the area where both the scanning electrode and the signal electrode are selected (quick selection point), it is necessary to align the liquid crystal molecules perpendicularly to the electrode surface. No voltage is applied to a region (non-governing point) where a voltage higher than the threshold is applied and neither the scanning electrode nor the signal electrode is selected, and therefore the liquid crystal molecules maintain a stable alignment parallel to the charge plane. By arranging linear polarizers above and below such a liquid crystal cell in a cross-Nicol relationship with each other, light does not pass through selected points, but light passes through non-selected points, making it possible to use it as a picture element. becomes. However,
When a matrix electrode structure is configured, there are areas where scan electrodes are selected and signal electrodes are not selected, or areas where scan electrodes are not selected and signal electrodes are selected (at 11").
The electric field is also finitely strong at the half-selected point (K).The difference between the voltage applied to the selected point and the voltage applied to the half-selected point is sufficiently large that the voltage required to align the liquid crystal molecules perpendicular to the electric field is 1%. If the peak value is set to this intermediate voltage [K, the display element will operate normally, but the scanning line a (M
), the time during which an effective electric field is applied to one selected point while scanning the entire screen (one frame) (iuty ratio) decreases at a rate of 17H. For this reason, the effective voltage difference between selected points and non-selected points when repeated scanning is performed becomes smaller as the number of scanning lines increases9, resulting in a decrease in image contrast. It is difficult to avoid crosstalk and crosstalk, which is a drawback. This phenomenon is caused by a highly bistable liquid crystal ('The stable state is when the liquid crystal molecules are oriented horizontally with respect to the Wt polar plane, and the liquid crystal molecules are oriented vertically only when an electric field is effectively applied This is an essentially unavoidable problem that arises when driving (orienting to) using the temporal accumulation effect (that is, scanning back and forth). In order to improve this point, voltage averaging method, dual-frequency driving method, multiple matrix method, etc. have already been proposed, but all of these methods are insufficient, and it is necessary to increase the screen size and density of display elements. Currently, the number of scanning lines has reached a plateau due to the inability to increase the number of scanning lines sufficiently.

On the other hand, if we look at the field of printers, laser beam printers provide electronic signals in the form of light to electrophotographic photoreceptors, both in terms of pixel density and speed, as a means of obtaining hard copies using electrical signals as input. (LBF) is also excellent in current quantity. However, with LBPK, the device used as a printer is larger = 2 It has a high-speed driving part such as a polygon scanner, and 1 It makes a loud noise.
Also strict 1. It has disadvantages such as requiring high mechanical precision; In order to overcome these drawbacks, a liquid crystal shutter array has been proposed as an element that converts electrical signals into optical signals. However, when providing pixel signals using a liquid crystal shutter array, for example, in order to write pixel signals at a rate of 16 dots/m within a length of 2105 m, it is necessary to have 3000 or more signal generating units. However, in order to give independent signals to each, it was originally necessary to wire +7- wires to send signals to all of the signal generating parts, which was difficult to manufacture.

For this reason, an attempt has been made to provide pixel signals for Nl (lines) in a time-division manner using a signal generating section divided into several lines. In this way, the electrodes that provide signals can be connected to a plurality of signal generating sections, and the amount of wiring can be substantially reduced. However, in this case, if the number of lines (N) is increased using a liquid crystal that does not have bistability, as is usually done, the signal ON time becomes substantially 1/M. The downside is that the amount of light that can be obtained at the top has been reduced, and there are problems with crosstalk.

Qlark and Lagerwall have proposed the use of a bistable liquid crystal element to improve the drawbacks of conventional liquid crystal elements (Japanese Patent Laid-Open No. 1983-1993).
-107214, U.S. Pat. No. 4,567,924, etc.). Bistable liquid crystals generally include chiral smectic 0 phase (SMA) or other chiral smectic phases, specifically chiral smectic H phase (
A ferroelectric liquid crystal having seven chiral smectic phases (8 mH*), a chiral smectic E phase (smx''), and a chiral smectic G phase (8 mG'') is used.

This liquid crystal exhibits an optically stable state of 1-1 and a state of optical stability of 2
It has a bistable state consisting of an optically stable state of
For example, the liquid crystal is aligned in a first optically stable state with respect to one electric field vector K, and the liquid crystal is aligned in a second optically stable state with respect to the other electric field vector. Additionally, this type of liquid crystal can respond to an applied electric field by very quickly taking one of the two stable states described above, and by maintaining that state when no electric field is applied. Substantial improvements are obtained over many of the problems of conventional TN type devices. This point will be explained in more detail below in connection with the present invention. However, in order for an optical modulation element using this bistable liquid crystal to exhibit predetermined drive characteristics, the liquid crystal placed between a pair of parallel substrates must be It is necessary that the molecules be in such a state that conversion between two stable states can occur effectively. For example, for strongly electrostatic liquid crystals with amc* or other chiral smectic phases, tJ, 8
It is necessary that a layer of liquid crystal molecules having mO or other chiral or smectic phase be perpendicular to the substrate surface, thus forming a region (monodomain) in which the liquid crystal molecular axes are aligned in approximately 1,000 rows on the substrate surface. 17 However, in conventional optical modulation elements using liquid crystals with bistable properties, sufficient characteristics cannot be obtained because the alignment state of the liquid crystals having such a monodomain structure is not always formed satisfactorily. The one that wasn't there was lol.

For example, a method of applying a magnetic field, a method of applying a shear force, etc. have been proposed to provide such an orientation state. However, none of these methods necessarily gave satisfactory results. for example,
The method of applying a magnetic field requires a large-scale device and is incompatible with thin-layer cells with good operating characteristics.The method of applying a shear force requires a large-scale device and is difficult to use in thin-layer cells with good operating characteristics. The problem is that it is incompatible with the injection method.

The main object of the present invention is to overcome the above-mentioned circumstances and to develop bistable devices that have potential suitability as display devices with high-speed response, high-density WJ elements and large areas, or optical shutters with high shutter speeds. In an optical modulation element using a liquid crystal having a liquid crystal, the present invention aims to improve the monodomain formation property or initial orientation property, which has been a problem in the past, and provides a method for controlling the orientation of a liquid that can exhibit its properties optically. There is a thing called K.

As a result of further research I7 for the above-mentioned purpose, the present inventors found that, in particular, when liquid crystal materials are in a different phase (for example, in a high-temperature state such as an isotropic phase),
We focused on the orientation during the cooling process in which the smectic phase transitions to a low-temperature state, and found that during the cooling process, the isotropic phase changes to the cholesteric phase, the smectic A phase, the chiral smectic 0 phase, and the chiral smectic H phase (SmH
At least one type of liquid crystal (hereinafter referred to as liquid crystal layer) that undergoes a phase transition to a chiral smectic phase (hereinafter referred to as a liquid crystal layer), such as a chiral smectic phase (8mG), and a phase transition from an isotropic phase to a cholesteric phase and a chiral smectic phase during the cooling process. When using a liquid crystal composition containing at least one type of liquid crystal that undergoes a phase transition to a chiral smectic phase (hereinafter referred to as liquid crystal B), the direction of the molecular axis of the liquid crystal is prioritized on the surface of the substrate that contacts the liquid crystal at the interface. When the effect of unidirectional alignment is imparted, it is possible to form monodomains in which liquid crystal molecules are aligned in one direction, and as a result, the operating characteristics of the device based on the bistability of liquid crystals and the monodomains of the liquid crystal layer can be improved. It has been found that it is possible to obtain a liquid crystal element having a structure that is compatible with properties and to improve alignment stability over a long period of time.

Furthermore, the present inventors have found that a liquid crystal composition in which a liquid crystal that undergoes a phase transition from an isotropic phase to a smectic human phase and a chiral smectic phase (hereinafter referred to as liquid crystal 0) in the liquid crystal composition during the cooling process is separated from the liquid crystal composition described above. It has been found that the liquid crystal composition described above also provides more stable alignment over a longer period of time.

Therefore, the present invention has a cell structure in which a liquid crystal composition containing the liquid crystal A and the liquid crystal B1 is sealed, and the surface of at least one of the pair of substrates is an interface. It is characterized by having the effect of preferentially aligning the molecular axes of the liquid crystal in one direction (1).

Hereinafter, the present invention will be described in further detail with reference to the drawings as necessary.

The liquid crystal composition used in the present invention exhibits ferroelectricity at a predetermined temperature. Examples of the liquid crystal M, liquid crystal B, and liquid crystal O described above are shown in Table 1, Table 2, and Table 5, respectively.

Table 1 Specific examples of liquid crystals (compound name, structural formula and phase transition point) 4-(2'-methylbutyl)phenyl-4'octyloxybiphenyl-4-carboxylate 78°C
80℃ 12B3℃ crystal! 8m3 = s
mo” +-8mA1 71.0℃ 174
．． 2°C - cholesteric phase -; a phase 4-pentylphenyl-4-(4'-methylhexyl)
Biphenyl-4'-carboxylate 91.5℃ 95℃ Crystal = 8mC*=smm 112℃ 131℃ = Cholesteric phase to isotropic phase (31p-11-octyloxybenzoic acid-du(2-
Methylbutyloxy)phenyl ester crystal: 8mO
: 8mA = cholesteric phase = isotropic phase Table 2 Specific examples of liquid crystal B (compound name, structural formula and phase transition point) 4-hexyloxyphenyl-4-(21-methylbutyl)piphenyl-4'-carboxylate 4-octyloxy Phenyl-4-(2'-methylbutyl)piphenyl-4'-carboxylate 76°C 88.6°C 155.4°C Crystallization smQ = Bresterik phase = Isotropic phase 4-(2'
-Methylbutyl)phenyl-4-(4'-methylhexyl)biphenyl-4' - carboxylate 83.4°C 114°C 55°C
95℃ 145℃ crystal: 9 m
Presterik phase on Q = isotropic phase table 5 Specific example of liquid crystal C (compound name, structural formula and phase transition point) P-decyloxybenzylidene-y-amino-2-methylbutylcinname) (DOBAMBO) 76°C
95℃ Crystal -48mO""; i 8mA: Isotropic phase P
60°C
64℃ 78℃ CrystalヰSmHヰ SmGヰ SmAヰ Isotropic phase P-decyloxybenzylidene-1-amino-2-methylbutyl-α-cyanosinname) (DOBAMBOO) 92℃
104℃ Crystal → 13mA: Isotropic phase P-tetradecytetraxybenzylidene-y-amino-2-
-Methylbutyl-α-cyanocinnamate (TDOBA)
MBOO) 78℃ 104℃ P-octyloxybenzylidene-1-amino-2-monomethylbutyl-α-chlorocinnamate (OOBAMB
CO) 41℃ 66℃ P-octyloxybenzylidene-P'-amino-2-
Monomethylbutyl-α-methylcinnamate crystal: El
mO: 8mA: Isotropic phase 4.4'-Azoxycinnamic acid-bis(2-methylbutyl) ester 121℃ 134℃ 168℃ Crystal;: BmO*: 8mA: Isotropic phase R 4-0-(2- Methyl)-pterresol cylidene-4-
-Octylaniline (MBRA8) 280°C 55°C 62°C crystal, 2-
Bm (4128 mA, 2-isotropic phase) The above-mentioned liquid crystals, liquid crystal B, and liquid crystal C can each be used in combination of two or more types.

The ratio of liquid crystal A to liquid crystal B in the liquid crystal composition used in the present invention varies depending on the type of liquid crystal used, but is generally 1.
The amount is 0.05 to 20 parts by weight, preferably 0.5 to 2 parts by weight, per part by weight of liquid crystal BK. The proportion of liquid crystal C in the liquid crystal composition is 0.1 to 40 wt., preferably 5 to 40 wt.
20 as a spear.

When constructing an element using these materials, the liquid crystal composition may be 8mO", 8mH", smy", Sm-9, SmG
In order to maintain the temperature state QK such that ``, the element can be supported by a rope block or the like in which a heater is embedded, if necessary.

The first ■ is strong li! An example of a cell is schematically drawn to explain the operation of an electroconductive liquid crystal. 11 and 11' are I
n, Os, BnOg or 工To ( 工n(lium
- A smo umbrella in which the Fcg crystal molecular layer 12 is oriented perpendicularly to the glass surface;
Chiral smectic phase liquid crystals such as BmFi*, gmy*, 8ml*, and 8mG umbrella are sealed. 1fs13 shown in bold line represents a liquid crystal molecule, and this liquid crystal molecule 1S has a dipole moment in the direction perpendicular to the molecule)
(P top) It has 14.

When a voltage higher than a certain threshold is applied between the electrodes on the substrates 11 and 11', the helical structure of the liquid crystal molecules 13 is unraveled, and the liquid crystal molecules 1S are aligned so that all the dipole moments (on P) 14 are oriented in the direction of the electric field. You can change direction. The liquid crystal molecules 13 have an elongated shape and exhibit refractive index anisotropy in the long axis direction and the short axis direction. Therefore, for example, if crossed Nicol polarizers are placed above and below the glass surface, depending on the voltage applied polarity, It is easily understood that this results in a liquid crystal optical modulation element whose optical properties change.

The liquid crystal cell preferably used in the optical modulation element of the present invention can have a sufficiently thin thickness (for example, 10 μm or less). As the liquid crystal layer becomes thinner in this way, as shown in FIG. 2, 'rl! Even when no L field is applied, the helical structure of the liquid crystal molecules unwinds, becoming a non-helical structure, and its dipole moment)? or y is upward (24
) or downward @ (takes either of the states shown in 24).To such a cell, an electric field E or 1 of different polarity above a certain threshold value is applied by voltage application means 21 and 21' as shown in Fig. 42. Then, the dipole moment changes its direction upward 24 or downward 24' in response to the electric field vector d, and the liquid crystal molecules accordingly move into the first stable state 23.
Or a second stable state! 1R23' orientation.

This kind of ferroelectricity can be optically modified by FJI! As mentioned earlier, there are two advantages to using it as an element.

The first is that the response speed is extremely fast. The second is that the alignment of liquid crystal molecules has bistability. To further explain the second point, for example with reference to FIG. 2, the electric field! When the voltage is applied, the liquid crystal molecules are aligned in the first stable state U23, and this state remains stable even when the electric field is turned off. Furthermore, when an electric field in the opposite direction is applied, the liquid crystal molecules enter the second stable state fff4.
The 25'lc orientation changes the orientation of the molecule, but it remains in this state even after the electric field is turned off.

Further, as long as the applied electric field E does not exceed a certain threshold value, each orientation state is maintained.

In order to effectively realize such fast response speed and bistability, it is preferable that the cell be as thin as possible.

As mentioned earlier, the biggest problem when forming an element with such a liquid crystal having ferroelectric properties is g and 8 m.
Monodomain property in which layers with chiral smectic phases such as O, 8mH, BmF, 13mI, and 8mG umbrellas are aligned perpendicular to the substrate surface, and liquid crystal molecules are aligned approximately parallel to the substrate surface. The key point is to form cells with a high level of energy, and the main purpose of the invention is to provide a solution to this point.

Figures R5 (m) and CB) show an embodiment of the liquid crystal element of the present invention. FIG. 3(M) is a plan view of the liquid crystal element of the great invention, and FIG. S(13) is a sectional view taken along the line A-A'.

In the cell structure 100 shown in FIG. 3, a pair of substrates 101 and 101' made of glass plates or plastic plates are held at a predetermined distance by a spacer 104, and an adhesive 106 is used to seal the pair of substrates. Has a cell structure glued with! , and furthermore, on the substrate 101, a plurality of transparent uA electrodes 102 (a group of electrodes (for example, a matrix '
The scanning voltage application electrode group (of the polarization structure) is formed in a predetermined pattern such as a strip pattern. Board 1
An electrode group (for example, the signal voltage applying electrode n of the matrix electrode set) consisting of a plurality of transparent quadrupole electrodes 102' intersecting with the transparent electrode 102 described above is formed on the electrode 01'.

The substrate 101' provided with such a transparent electrode 102' has
For example - silicon oxide, fluorine dioxide, aluminum oxide,
Inorganic insulating materials such as zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide, boron nitride, polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, borinol, polyester, polycarbonate, polyvinyl The alignment control film 105 may be formed using an organic insulating material such as acetal, polyvinyl chloride, polyamide, polystyrene, cellulose resin, melamine resin, area resin, or acrylic resin.

This orientation control film 105 is obtained by forming a film of the above-described inorganic or organic insulating material and then rubbing the surface in one direction with a bead, cloth, or paper.

In another preferred embodiment of the present invention, an inorganic insulating material such as slo or 810t is deposited on the substrate 101' using an oblique evaporation method. By forming the film, the orientation control film 105
can be obtained.

In the apparatus shown in FIG. 5, a pelger 501 is placed on a vacuum substrate 503 having a suction port 505, and a vacuum pump (not shown) extends from the suction port 505.
The Pel jar 501 is then evacuated. A crucible 507 made of tungsten leaf or molybdenum is placed inside and at the bottom of the Pel jar 501, and several grams of crystals 508 such as 810° 810t, MPPt, etc. are aa in the crucible 507. The crucible 507 has two arms 507a and 5 of T1.
07b, and said arms have grooves @ 509, 510, respectively.
connected to.

[$506 and switch 504 are connected in series between external conductors 509 and 510 of Pelger 501. Substrate 50
2 is placed inside the Pel jar 501 directly above the crucible 507 at an angle of θ with respect to the vertical axis of the Pel jar 501.

When the switch 504 is opened, the Pelger 501 is first brought to a vacuum of approximately 10-5 m5 + HF pressure, and then the switch 504 is closed and the power supply 506 is turned on until the crucible 507 is incandescent at a suitable temperature and the crystal 508 is evaporated. Power is supplied in a regulated manner. The required current for a suitable temperature range (700-100°C) is about 1°OOamps. crystal 50
B is then evaporated and releases an upward molecular flow indicated by S in the figure, and the fluid S is incident on the substrate 502 at an angle of θ with respect to the substrate 502, resulting in the substrate 502 being coated. The angle θ is the above-mentioned 1 incident angle, and the direction of the fluid direction is the above-mentioned 1 oblique deposition direction.

The film thickness of the coating is determined by A1. It is determined by the calibration of the thickness with respect to time t. When a film of appropriate thickness is formed, the power from the power source 506 is reduced and the switch 5 is turned off.
04 is opened to cool the Pel jar 501 and its inside. Next, the pressure is increased to atmospheric pressure and the substrate 502 is placed on the Pelger 5.
Remove it from 01.

(9) In another specific example, after forming a film of the above-mentioned insulating material or organic insulating material on the surface of the substrate 101' made of glass or plastic or on the substrate 101', the surface of the film is etched by an oblique etching method. By etching the surface, an orientation control effect can be imparted to the surface. .

It is preferable that the above-mentioned orientation control film 105 also functions as a simultaneous Ke film, and for this purpose, this orientation control 1!1
The film thickness of 05 is generally 100A to 1μ, preferably 500A
It can be set in the range of 1 to 5000^. This insulating film also has the advantage of preventing the generation of current caused by impurities contained in the liquid crystal layer 103, and therefore does not deteriorate the liquid crystal compound even if the operation is repeated. do not have.

Further, in the liquid crystal element of the present invention, a film similar to the above-mentioned alignment control film 105 can be provided on the other substrate 101.

The liquid crystal layer 103 in the cell structure 100 shown in FIG.
sI! , c”, SmH”, smF”, 8ml”, 8m
The chiral smectic liquid crystal layer 105 contains the above-mentioned liquid crystal layer and liquid crystal B, more preferably liquid crystal C.

With this invention! An important point is that when a liquid crystal composition containing the liquid crystal A and liquid crystal B described above is used to cause a phase transition from a high temperature phase to a smectic phase or a chiral smectic phase, this liquid crystal molecular axis is imparted to the alignment control film 105. As a result, uniform monodomains are formed, and the orientation is not disturbed at all even during long-term storage.

Figure @4 shows another specific example of the liquid crystal element of the present invention. The liquid crystal element shown in FIG. 4 consists of a pair of substrates 101 and 10.
Km number of spacer members 201 are arranged between 1'. This spacer member 201 is, for example, an orientation control $105
K 1310. E
liO,, A/, O,, T2O, Inorganic compounds such as polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparaxylylene, polyester, polycarzenate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate After forming a film of resin such as polyamide, polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin, or photoresist resin by an appropriate method, place the spacer member 2 at a predetermined position.
It can be obtained by etching so that 01 is arranged.

These various cell structures 100Fi, substrates 101 and 101'
Polarizers 107 and 108 which are in a 111 Ka/Ross Nicol state or 11/<9 rel Nicol state are arranged respectively, and optical modulation occurs when a voltage is applied between the electrodes 102 and 102'.

Next, regarding the method for manufacturing the liquid crystal element of the present invention, the liquid crystal layer 105
The orientation control method will be specifically explained using FIG. 5.

First, the cell structure 100 in which the liquid crystal composition is sealed is placed in a heating case (
(not shown) K is set.

Next, the liquid crystal composition in the cell 10G is heated to a temperature at which it becomes an isotropic phase. Thereafter, the temperature of the heating case is lowered, and the liquid crystal composition in the isotropic phase in the cell 100 is transferred to the temperature lowering process.

FIG. 6 is a schematic diagram of a cell 41 having a matrix electrode structure in which a ferroelectric liquid crystal compound is sandwiched in the middle. 42 is a scanning electrode group, and 43 is a signal electrode group. Figure 7 (a
) and (1)) are respectively selected scanning electrodes 42(a
)Ic shows the electrical signal given to the other scanning □scanning electrodes (unselected scanning electrodes) 42(n).

FIGS. 6(0) and 6(i) represent the electric signal applied to the selected signal electrode 43 (s) and the electric signal applied to the unselected signal electrode 45 (n) Ic, respectively.

In FIGS. 7(a) to 7(a), the horizontal axis represents time and the vertical axis represents voltage. For example, when displaying a moving image, the scanning electrode groups 42 are sequentially and periodically selected. Now, if the threshold voltage for providing the first stable state of the liquid crystal cell having bistable property is vthl, and the threshold voltage for providing the second stable state is -vth2, then the selected scan electrode 42 (s ) is the electrical signal given to
As shown in FIG. 7(L), the phase (time) t.

It is an alternating voltage that becomes V at phase (time) t2 and -V at phase (time) t2. In addition, other scanning electrodes 42 (n)
is in a ground state as shown in FIG. 7 (1)), and the electrical signal is 0. On the other hand, the selected signal electrode 4
5 (s) K The electric signal applied is v as shown in FIG. 7 (0), and the unselected signal electrode 45 (
The electric signal given to n) is (-4) as shown in FIG. Figure 8 shows the voltage waveform applied to each pixel when such an electric signal is applied. 6
Pixels A, B, C in the figure! and corresponds to D. That is, as is clear from FIG. 8, a voltage of 2v exceeding the threshold value vth is applied to the pixels on the selected scanning line at phase t2. Also, the image XB that exists on the same scanning line
In this case, a voltage -2v exceeding the threshold value -vth2 is applied at phase t1. Therefore, depending on whether or not a signal electrode is selected on the selected scanning electrode line, if the signal electrode is selected, the liquid crystal molecules are in the first stable state (aligned alignment, and if not selected, the liquid crystal molecules are in the second stable state). In any case, it is not related to the previous history of each pixel. On the other hand, as shown in pixels ○ and DK, on the scan line that is not selected, it is applied to all pixels 0.!-D. The voltage is +
V or -V, neither of which exceeds the threshold voltage. Therefore, the liquid crystal molecules in each pixel C and D maintain the orientation corresponding to the signal state when scanned last time without changing the orientation state. That is, when a scanning electrode is selected, a signal for one line of K is written,
- The signal state can be maintained until the next selection after the end of the frame. Therefore, even if the number of scanning electrodes increases, the actual duty ratio does not change, and no reduction in contrast or distortion occurs at all. On this occasion.

Value of voltage value V and phase (t, +t2) == The value of T depends on the liquid crystal material used and the thickness of the cell, but is usually 0.1 μsec to 3 volts to 70 volts.
A range of 2 maea is used. Therefore, in this case, the electrical signal applied to the selected scanning electrode changes from the first stable state (assumed to be in the "bright" state when converted to an optical signal) to the second stable state (assumed to be a "bright" state when converted to an optical signal). and′f!”
A change can occur either from the dark state to the dark state or vice versa. EImO” mentioned above, 8
WIE”, 8mF”.

Compared to the case where a liquid crystal exhibiting a chi2lsmectic phase such as "Elml" or "BmG" is used alone, when the liquid crystal composition used in the present invention is used, an alignment state with good alignment properties and fewer alignment defects can be obtained.

Especially when the cell thickness is thin or bistability (memory property)
8mC”, 8mH*, 8mF”, 8mI” with
.

In the case of a chi2lsmectic phase such as SmG, the restraining force (effect of substrate alignment treatment) on liquid crystal molecules on the substrate surface is 1 in terms of switching characteristics (response speed).
The weaker the strength, the better. Therefore, when only one substrate surface is aligned, a faster response speed can be obtained than when both substrate surfaces are aligned. At this time, the cell thickness is 2
In a μm cell, when only one side of the substrate is subjected to alignment treatment, a response speed approximately twice as fast as that when both substrates are aligned can be obtained.

Hereinafter, the present invention will be explained according to examples.

[Example 1] A square glass substrate was prepared, on which a striped TO film with a pitch of 100 μm and a width of 62.5 μm was provided as an electrode.
This was set in the oblique evaporation apparatus shown in FIG. 5 with the side on which the TO film serving as the electrode was provided facing downward, and then a crystal of SiO□ was set in a molybdenum furnace.

After that, the inside of the evaporation apparatus is made into a vacuum state of about 10" Torr, and then 8102 cm is deposited on the glass substrate using a predetermined method.
was obliquely deposited to form an obliquely deposited film of 800 people (A electrode plate).

On the other hand, a polyimide forming solution ("P-Q" manufactured by Hitachi Chemical Co., Ltd., non-volatile content concentration 14.5 wt%) was applied using a spinner coating machine onto a glass substrate on which a similar striped TO film was formed. and then at 120℃ for 30 minutes and at 200℃ for 6 minutes.
800 minutes and heated at 330℃ for 30 minutes.
A film of X was formed (B [electrode plate)].

Next, a thermosetting epoxy adhesive was applied to the periphery of the Bt electrode plate by screen printing, except for the area that would become the injection hole, and after post-mortem, the Bt electrode plate and the Bt electrode plate striped pattern electrodes were superimposed so that they were perpendicular to each other. , the distance between the two electrode plates is 2
It was maintained with a polyimide spacer to maintain μ and was made into a cell.

Next, diphenyl-4-(2-
A liquid crystal composition was prepared by adding 75 parts by weight of '-methylbutyl)biphenyl-4'-carboxylate.

This liquid crystal composition was heated to have an isotropic phase, prepared as described above, and injected into the cell through the injection port, and the injection port was sealed. After the temperature of this cell was lowered by slow cooling, a pair of polarizers was placed in a crossed nicol state, and the result was observed under a microscope.
It was confirmed that smc'' with a monodomain non-helical structure was formed.

Furthermore, after maintaining this liquid crystal element in the BmC'' state for 700 hours, similar microscopic observation was performed again, and it was confirmed that it was still BmO'' with a monodomain non-helical structure.

On the other hand, as a comparative experiment, liquid crystal elements were created in the same manner as described above, except that each of the liquid crystals used in the liquid crystal element described above was used alone.

Microscopic observation confirmed the formation of monodomain non-helical structure BmC'' in the early stages of each case, but after 700 hours of durability testing, am(!* indicates mono No domain was formed.

In addition, the liquid crystal composition 100I! used in the above-mentioned Examples! 1ilJll! of a liquid crystal composition to which 20 parts by weight of DOBAMBC was added! When a liquid crystal element was prepared using this composition in the same manner as described above and then observed under a microscope, it was found that an SMC* with a monodomain non-helical structure was formed even in the initial stage, and it was found that it was more durable. Monodomain SmO” was formed even after the test was extended for 1000 hours compared to the previous example.〇 [Example 2] Striped TO film with a pitch of 100 μm and a length of 662.55 m. A polyimide forming solution ("P-Q" manufactured by Hitachi Chemical Co., Ltd.; non-volatile content concentration 14.5 wt%) was coated on a square glass substrate provided with as an electrode using a spinner coater, and then heated at 120° C. for 30 minutes. 60 minutes at 200°C, then 3
Heating was performed at 30° C. for 50 minutes to form an 800X coating (Affi plate).

Next, the polyimide coated electrode plate obtained in the same manner as above was subjected to a 7-bing treatment using a cloth. (B electrode plate) Next, a thermosetting clear embossed medium adhesive was applied to the periphery of the M electrode plate by screen printing, except for the area that would become the injection hole. The pattern electrodes are stacked so that they are perpendicular to each other, and the interval between the two electrode plates is 2.
4-Pentylphenyl-4-(4'-methylhexyl) held with a polyimide spacer so as to be μ and made into a cell
70 parts by weight of 4-octyloxyphenyl-4-(2'-methylbutyl)biphenyl-4'-carboxylate
A liquid crystal composition was prepared by adding parts by weight. This liquid crystal composition was heated and injected into a cell made into a liquid crystal composition through an injection port, and the injection port was sealed. After lowering the temperature of this cell by slow cooling, a pair of polarizers were installed in a crossed Nicol state, and microscopic observation revealed that the monodomain non-helical structure of the sm
It was confirmed that "a" was formed.

Furthermore, after maintaining this liquid crystal element in the BmO'' state for 700 hours, the same microscopic observation was performed again, and it was confirmed that it was still a monodomain non-helical structure SMC''.

On the other hand, as a comparative experiment, we used each of the liquid crystals used in the above-mentioned liquid crystal elements alone, and after creating the liquid crystal elements in the same manner as the above-mentioned method, we observed them under a microscope. However, after a 700-hour durability test, smc'' did not form a monodomain.

In addition, a liquid crystal composition was prepared by adding 20 parts by weight of DOBAMBO to 100 parts by weight of the liquid crystal composition used in the above example, and a liquid crystal element was created using this composition in the same manner as above. Afterwards, microscopic observation revealed that smc* with a monodomain non-helical structure was formed even at the initial stage.

Furthermore, monodomain smo* was still formed even after death, when the durability test was carried out for 91,000 hours longer than in the case of the previous example.

[Examples 3 and 4] Instead of 4-(2'-methylbutyl)phenyl-4'-octyloxybiphenyl-4-carboxylate used in Example 1, 4-pentylphenyl-4-(4'-methyl hexyl) and 722-4'-carboxylate (
Example 5), p-n-octyloxybenzoic acid-p'-
(2-methylbutyloxy)phenyl ester C'At
A liquid crystal device was prepared in the same manner as in Example 1, except that 1lA Example 4) was used, and microscopic observation revealed that smo* with a monodomain non-helical structure was formed.

Furthermore, for each example, 700
When we conducted a time durability test, we found that monodomain's am
It was confirmed that it was a*.

Furthermore, in place of DOBAMBO used in Example 1.

Using HOBAC+PC, Nine et al. created a liquid crystal element in the same manner as described above, and then conducted the same test, and found that in both Examples 5 and 4, at the initial stage and at the stage after 170 o hour durability. Monodomain BmO” was confirmed.

[Example 5] Plastic substrate K was prepared by forming a transparent conductive film containing indium oxide as a main component on a 100 μm polyethylene terephthalate film using a low-temperature sputtering device by keeping the film surface temperature below 120°C, and a solution having the following composition (solution composition (
1)) was applied and dried at 120°C for 30 minutes to form a thin film.

Solution composition (1) Acetomethoxyaluminum diisopropylate polyester resin (Toyobo: Pylon 50F) 0.5J
Tet2hydrofuran 100 mi.

Next, rubbing was performed in one direction under the pressure of K, 100', 9/α2, and the rubbed pair of glass substrates were stacked on top of each other so that the upper and lower rubbing directions were parallel to each other, and the portion that would become the injection port was removed. The area around it was sealed. The distance between the pair of glass substrates at this time is 1μ.

Next, 80 parts by weight of 4-(2'-methylbutyl)phenyl-#)piphenyl-4'-carboxylate was added to prepare a liquid crystal composition.

This liquid crystal composition was heated to form a liquid crystal composition, prepared as described above, and injected into the cell through the injection port under reduced pressure, and the injection port was sealed. After the temperature of this cell was lowered by slow cooling, a pair of polarizers were placed in a crossed nicol state, and microscopic observation revealed that SmO'' with a monodomain non-helical structure was formed.

Furthermore, after maintaining this liquid crystal element in the SmO'' state for 500 hours, similar microscopic observation was performed again, and it was confirmed that it was still BmC* with a monodomain non-helical structure.

On the other hand, as a comparative experiment, liquid crystal elements were fabricated in the same manner as described above, except that each of the liquid crystals used in the liquid crystal element described above was used alone, and then microscopic observation was performed. Although it was confirmed that 13mG* had a monodomain non-helical structure, SmC'' did not form a monodomain after a 500-hour durability test.

Further, a liquid crystal composition was prepared by adding 20 parts by weight of OOBAMBOO to 100 parts by weight of the liquid crystal composition used in the above example, and a liquid crystal element was created using this composition in the same manner as above. After that, microscopic observation was performed, and it was found that
Even at the initial stage, amc* with a monodomain non-helical structure was formed, and the durability test was further conducted to 6o compared to the case of the above-mentioned example.

Monodomain BmC even after extended time
was formed.

[Examples 6 and 7] The 4-(2'-methylbutyl)phenyl-4'-ofderoxybiphenyl-4-carboxylate used in Example 5 was chemically modified to produce 4-pentylphenyl-4-(4'-
methylhexyl) piphenyl-4'-carboxylate (Example 6), p-n-octyloxybenzoic acid-p'
-(2-methylbutyloxy)phenyl ester (Real M
A liquid crystal element was prepared in the same manner as in Example 5, except that Example 7) was used, and when it was observed under a microscope, it was found that SmC'' with a monodomain non-helical structure was formed. A 700-hour durability test similar to that of Example 2 was conducted for this example, and it was found that monodomain E3mO
It was confirmed that *.

Furthermore, instead of OOBAMBOOK used in Example 5,
Except for using DOBAMBCt, liquid crystal elements were prepared in the same manner as described above, and then the same tests were conducted. monodomain smc” was confirmed.

[Examples 8 and 9] 4-pentylphenyl-4-(al-
4-(2'-methylbutyl)phenyl-4 instead of methylhexyl)biphenyl-4'-carboxylate
'-Octyloxybiphenyl-4-carboxylate (example day), p-n-octyloxybenzoic acid-p'
-(2-methylbutyloxy)phenyl ester (real m
A liquid crystal device was prepared in the same manner as in Example 2, except that fFl19) was used, and microscopic observation revealed that SmO* with a monodomain non-helical structure was formed.

K, 700 for each example as in Example 2 above.
When we conducted a time durability test, we found that monodomain's am
It was confirmed that "A".

Furthermore, instead of DOBAMBO used in Example 2, M
A liquid crystal element was prepared in the same manner as described above, except that BRA 8 was used, and the same test was conducted. Thus, monodomain SmO'' was confirmed.

[Brief explanation of the drawing]

1 and 2 are perspective views showing a liquid crystal cell used in the present invention. FIG. 3(M) is a plan view showing the liquid crystal element of the present invention, and FIG. 3(CB) is a cross-sectional view of the same. FIG. 4 is a sectional view showing another specific example of the liquid crystal element of the present invention. FIG. 5 is a cross-sectional view schematically showing an oblique evaporation apparatus used in producing the liquid crystal element of the present invention. FIG. 6 is a plan view schematically showing the electrode structure of the liquid crystal element used in the present invention. FIGS. 7(CL) to 7(d) are explanatory diagrams showing signals for driving the liquid crystal element used in the present invention. FIGS. 8(a) to (d). FIG. 3 is an explanatory diagram showing a voltage waveform applied to each pixel. 100... Cell structure 101.101'... Substrate 102.102'... Electrode 103... Liquid crystal layer 104.201... Spacer member 105... Orientation control film 106... Adhesive 107.108... Deflector 109... Heating element 21' 10Z 10j; (')))
(dn(b) C) --Vtkt (d) ---7th

Claims (1)

[Scope of Claims] (1) At least one type of liquid crystal that undergoes a phase transition from an isotropic phase to a cholesteric phase, a smectic A phase, and a chiral smectic phase during a cooling process and an isotropic phase during a cooling process in a pair of substrates. It has a cell structure in which a liquid crystal composition containing at least one type of liquid crystal that undergoes a phase transition from to a cholesteric phase to a chiral smectic phase is enclosed, and the surface of at least one of the pair of substrates contacts at an interface. A liquid crystal element characterized by having the effect of preferentially aligning the molecular axis direction of liquid crystal in one direction. (2) Claim 1, wherein the chiral smetic phase is C phase, H phase, F phase, J phase, K phase, I phase, or G phase.
The liquid crystal element described in . (3) The liquid crystal element according to claim 1 or 2, wherein the chiral smetic phase has a non-helical structure. (4) A patent claim in which the surface of one of the pair of substrates has an effect of preferentially aligning the molecular axis direction of liquid crystal in one direction, and the surface of the other substrate does not have the effect. The liquid crystal element according to range 1. (5) Claim 1 or 4, wherein the surface having the above-mentioned effect is a surface obtained by rubbing the surface of the substrate.
The liquid crystal element described in . (6) The liquid crystal element according to claim 5, wherein the surface is a surface formed of a film of an organic insulating material or an inorganic insulating material. (7) The organic insulating material is polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparaxylylene, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, urea. 7. The liquid crystal element according to claim 6, wherein the resin is at least one selected from the resin group consisting of resin, acrylic resin, and photoresist resin. (8) The inorganic insulating material is SiO, SiO_2 or Ti
The liquid crystal element according to claim 6, which is O_2. (9) The liquid crystal element according to claim 1 or 4, wherein the surface having the effect is obtained by obliquely depositing an insulating material on the surface of the substrate. (10) The liquid crystal element according to claim 9, wherein the insulating material is SiO or SiO_2. (11) The liquid crystal element according to claim 1 or 4, wherein the surface having the effect is a surface obtained by obliquely etching the surface of the substrate. (12) The liquid crystal element according to claim 11, wherein the surface is a surface formed by a coating or a substrate of an organic or inorganic insulating material. (13) the organic insulating material is polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparaxylylene, polyester, polycarbonate,
Claim 12, which is a resin selected from the group consisting of polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin, and photoresist resin. The liquid crystal element described in . (14) The inorganic insulating material is glass, SiO, SiO_
13. The liquid crystal element according to claim 12, which is TiO_2 or TiO_2. (15) The liquid crystal element according to claim 1, wherein the other substrate is a substrate including a spacer member obtained by forming a film of an insulating material and then etching except for a predetermined position. (16) The liquid crystal element according to claim 15, wherein the spacer member is a band-shaped member. (17) The liquid crystal element according to claim 16, which is an element comprising a plurality of the band-shaped spacer members. (18) At least one type of liquid crystal that undergoes a phase transition from an isotropic phase to a smectic A phase and a chiral smectic phase during a cooling process, and a liquid crystal that undergoes a phase transition from an isotropic phase to a cholesteric phase, a smectic A phase, and a chiral smectic phase during a temperature cooling process on a pair of substrates. A cell encapsulating a liquid crystal composition containing at least one type of liquid crystal that undergoes a phase transition to a smectic phase and at least one type of liquid crystal that causes a phase transition from an isotropic phase to a cholesteric phase and a chiral smectic phase during a cooling process. structure,
A liquid crystal element characterized in that the surface of at least one of the pair of substrates has the effect of preferentially aligning the molecular axis direction of the liquid crystal that contacts at an interface in one direction. (19) The chiral smetic phase is C phase, H phase, F phase
19. The liquid crystal element according to claim 18, which is a phase, J phase, K phase, I phase, or G phase. (20) The liquid crystal element according to claim 18 or 19, wherein the chiral smetic phase has a non-helical structure. (21) The surface of one of the pair of substrates has the effect of preferentially aligning the molecular axis direction of the liquid crystal in one direction,
19. The liquid crystal element according to claim 18, wherein the surface of the other substrate does not have the effect. (22) The liquid crystal element according to claim 18 or 21, wherein the surface having the effect is a surface obtained by rubbing the surface of a substrate. (25) The liquid crystal element according to claim 22, wherein the surface is a surface formed of a film of an organic insulating material or an inorganic insulating material. (24) the organic insulating material is polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparaxylylene, polyester, polycarbonate,
Claim 23: The resin is at least one selected from the group consisting of polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin, and photoresist resin. The liquid crystal element described in . (25) The inorganic insulating material is SiO, SiO_2 or T
The liquid crystal element according to claim 23, which is iO_2. (26) The liquid crystal element according to claim 18 or 21, wherein the surface having the effect is a surface obtained by diagonally depositing an insulating material on the surface of the substrate. (27) The liquid crystal element according to claim 26, wherein the insulating material is SiO or SiO_2. (28) The liquid crystal element according to claim 18 or 21, wherein the surface having the effect is a surface obtained by obliquely etching the surface of the substrate. (29) The liquid crystal element according to claim 28, wherein the surface is a surface formed by a coating or a substrate of an organic or inorganic insulating material. (30) the organic insulating material is polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparaxylylene, polyester, polycarbonate,
Claim 29 The resin is at least one selected from the group consisting of polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin, and photoresist resin. The liquid crystal element described in . (31) The inorganic insulating material is glass, SiO, SiO_
31. The liquid crystal element according to claim 30, which is TiO_2 or TiO_2. (32) Claim 18, wherein the other substrate is a substrate provided with a spacer member obtained by forming a film of an insulating material and then etching it except for a predetermined position.
The liquid crystal element described in . (33) The liquid crystal element according to claim 32, wherein the spacer member is a band-shaped member. (34) The liquid crystal element according to claim 33, which is an element comprising a plurality of the band-shaped spacer members.