JPS6125127A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To allow operation characteristics of the element based upon the bistability of liquid crystal and the monodomain property of a liquid crystal layer to consist together by providing a coupl of substrates across a liquid-crystal compound consisting of liquid crystal showing Sm* and liquid crystal having a cholesteric phase, and performing a specific orientation treatment for at least either of the substrates. CONSTITUTION:The couple of substrates 101 and 101' are held at a specific interval by using spacers 104 and adhered together with an adhesive agent 106; plural transparent electrodes 102 are formed on the substrate 101 in a specific pattern and plural transparent electrodes 102' crossing the electrodes 102 are formed on the substrate 101'. An orientation control film 105 is formed on the substrate 101' by vapor-depositing SiO, SiO2, etc., and rubbed in one direction as the orientation treatment. The liquid crystal compound 13 consisting of the liquid crystal which shifts in phase from SmA to Sm*-G in order and the cholesteric liquid crystal is charged between the substrates 101 and 101'. Consequently, the liquid crystal element 100 which has both the operation characteristics of the element 100 based upon the bistability of the liquid crystal 103 and the monodomain property of the liquid crystal layer 103.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal element used in a liquid crystal display element, a liquid crystal-light shutter, etc.
The present invention relates to a liquid crystal element that has improved display and driving characteristics through various improvements.

Conventionally, liquid crystal display elements display a single image 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.
The well-known driving method for this display element is as follows:
selectively and periodically applying address signals to the scanning electrode group;
Time-division driving is adopted in which a predetermined information signal is selectively applied in parallel in synchronization with an address signal to the signal electrode group, but this display element and its driving method have the following critical drawbacks. There are drawbacks.

That is, it is difficult to increase the pixel density or enlarge the screen. Among conventional liquid crystals, most of them are practically used as single display elements because of their relatively high response speed and low power consumption, such as M, 5-channel.
dj and W, He1frich “Applied Ph
ysics Letters” Vo, 18°No, 4
(1971, 2, 15), P, 127-128 “V
oltage-Dependent 0ptical
Activity of a Twisted Ne
This type of liquid crystal uses a TN (twisted nemaLic) type liquid crystal shown in ``matic Liquid Cry'5tal'', and this type of liquid crystal has molecules of nebtic liquid crystal, which has positive dielectric anisotropy in an electroless state, in a liquid crystal layer. A twisted structure (helical structure) is formed in the thickness direction, and molecules of this liquid crystal are arranged in parallel between the two electrodes.On the other hand, when an electric field is applied, a nebutic structure with positive dielectric anisotropy is formed. The liquid crystals are aligned in the direction of the electric field, and as a result, optical modulation can occur.When a display element is constructed using this type of liquid crystal with a matrix electrode structure, the area where both the scanning electrode and the signal electrode are selected (the selection point ), a voltage higher than the threshold required to align liquid crystal molecules perpendicular to the electrode surface is applied to the area (
No voltage is applied to the non-selected points), so the liquid crystal molecules maintain a stable alignment parallel to the electrode plane. By arranging linear polarizers above and below 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 an image element. Become. However, when a matrix electrode structure is configured, there is a possibility that the scan electrodes are selected and the signal electrodes are not selected, or the scan electrodes are not selected and the signal electrodes are selected (so-called "half-selected points"). The difference between the voltage applied to the 0 selection point, where a finite electric field is applied, and the voltage applied to the half selection point is sufficiently large, and the voltage threshold required to align the liquid crystal molecules perpendicular to the electric field is set to an intermediate voltage value. If the number of scanning lines (N) is increased, the display element will operate normally.
The time during which an effective electric field is applied to one selected point (duty ratio) decreases at a rate of 17H during scanning of one selected point (one frame).For this reason, the selected point and non-selected point when scanning repeatedly is reduced. The voltage difference as an effective value across the selected point is
As the number of scanning lines increases, the size becomes smaller, resulting in unavoidable drawbacks such as a reduction in image contrast and crosstalk. This phenomenon is caused by liquid crystals that do not have bistability (the stable state is when the liquid crystal molecules are aligned horizontally with respect to the electrode surface, and they are aligned vertically only while an electric field is effectively applied). ) is an essentially unavoidable problem that occurs when driving using the temporal accumulation effect (that is, repeatedly scanning).To improve this point, voltage averaging method, dual frequency driving Already proposed methods include the multi-matrix method and the multiple matrix method, but all of these methods are insufficient, and the ability to increase the screen size and density of display devices has reached a plateau due to the inability to increase the number of scanning lines sufficiently. The current situation is that

On the other hand, looking at the field of pre-printers, as a means of obtaining hard copies using electrical signals as input, it is possible to apply electrical image signals in the form of light to an electrophotographic photoreceptor in terms of both pixel density and speed. Printer (L
BP) is currently the best. However, LBP has the following drawbacks: 1. The printer is large; 2. It has high-speed moving parts like a polygon scanner, which generates noise, and requires strict 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 dat/mm within a length of 219 mm, it is necessary to have 3000 or more signal generating units. First, in order to provide independent signals to each, it was originally necessary to wire lead wires to send signals to each signal generating section, which was difficult to manufacture.

Therefore, an attempt has been made to provide pixel signals for ILINE (line) in a time-division manner using a signal generating section divided into several lines. In this way, the electrode that gives the signal can be
This is because it can be made common to a plurality of signal generating sections, and the actual wiring can be significantly reduced. However, if the number of lines (N) is increased using a liquid crystal that does not have bistability, as is usually done in this case, the signal ON time becomes essentially 1/N, which reduces the amount of light that can be obtained on the photoreceptor. The disadvantage is that the amount of light emitted is reduced, leading to crosstalk problems.

To improve these drawbacks of conventional liquid crystal devices, the use of bistable liquid crystal devices has been proposed by C1ark and Lagsrwal 1 (
JP-A-56-107216, U.S. Patent No. 4367
No. 924 specification, etc.), and the bistable liquid crystals are generally:
Chiral smectic C phase (3m0 pieces) or other chiral smectic, Ick phase, specifically chiral smectic H phase (SmH pieces), chiral smectic F phase (SmF pieces), chiral smectic I phase (SmI
”), and chiral smectic G phase (SmG”)
This liquid crystal has a bistable state consisting of a first optically stable state and a second optically stable state in response to an electric field. Unlike optical modulation elements, for example, the liquid crystal is aligned in a first optically stable state with respect to one electric field vector, and the liquid crystal is aligned in a second optically stable state with respect to the other electric field vector. In addition, this type of liquid crystal
In response to an applied electric field, it very quickly assumes one of the two stable states, and maintains that state when no electric field is applied. By utilizing such properties, considerable improvements can be obtained in many of the problems of the conventional TN type elements mentioned above.

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, it is necessary to
It is necessary that the liquid crystal disposed between the pair of parallel substrates be in a molecular arrangement state that effectively converts between the two stable states, regardless of the state of application of an electric field.

For example, for ferroelectric liquid crystals with SmC* or other chiral smectic phases, the liquid crystal molecular layer with SmC books or other chiral smectic phases is perpendicular to the substrate plane, so that the liquid crystal molecular axes are in the substrate plane. It is necessary to form regions (monodomains) arranged approximately in parallel. However, in conventional optical modulation elements using liquid crystals with bistable properties, the alignment state of the liquid crystals having such a monodomain structure was not always formed satisfactorily, and therefore sufficient characteristics could not be obtained. is the reality.

For example, in order to provide such an orientation state, methods such as applying an ai field and applying a shear force have been proposed. However, none of these methods necessarily gave satisfactory results. For example, the method of applying a magnetic field requires large-scale equipment and is incompatible with thin-layer cells with good operating characteristics. This method has the disadvantage that it is incompatible with the method of injecting liquid crystal.

In view of the above-mentioned circumstances, the main object of the present invention is to develop a bistable device that has potential suitability for use in display elements with high-speed response, high-density pixels, and large area, or optical shutters with high shutter speeds. An object of the present invention is to provide a method for controlling the alignment of a liquid crystal that can fully exhibit its characteristics by improving monodomain formation or initial alignment, which has been a problem in the past, in an optical modulation element using a liquid crystal.

As a result of further research for the above-mentioned purpose, the present inventors found that, in particular, when the temperature decreases, the liquid crystal material transitions from another phase (e.g., a high temperature state such as a smectic phase) to a low temperature state such as a smectic phase, such as SmA (smectic A phase). Focusing on the orientation in the process, we found that at least chiral smectic C phase (S
mC”), chiral smectic H phase (SmH book), chiral smectic F phase (SmF powder),
When using a liquid crystal composition containing a liquid crystal exhibiting a chiral smectic phase such as a chiral smectic I phase (SmI phase) and a chiral smectic G phase (SmC phase), and a liquid crystal exhibiting at least a cholesteric phase,
'By giving the surface of the substrate in contact with the liquid crystal at the interface an effect that prioritizes the direction of the molecular axis of the liquid crystal and aligns it in one direction.
For example, liquid crystal molecules of SmA can form a monodomain in which they are aligned in one direction, and as a result, the liquid crystal element has a structure that allows both the operating characteristics of the element based on the bistability of the liquid crystal and the monodomain property of the liquid crystal layer. was found to be obtained.

The present invention is based on the above-mentioned knowledge, that is, the liquid crystal element of the present invention is a liquid crystal composition containing, between a pair of substrates, a liquid crystal exhibiting at least a chiral smectic phase and a liquid crystal exhibiting at least a cholestic phase. , and has a cell structure in which a liquid crystal composition exhibiting a chiral smectic phase at a predetermined temperature is enclosed, and the surface of at least one of the pair of substrates is oriented in one direction with priority given to the molecular axis direction of the liquid crystal that contacts at the interface. It is characterized by having an orienting effect.

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 contains at least a liquid crystal exhibiting a chiral smectic phase and a liquid crystal exhibiting at least a cholesteric phase, and has ferroelectricity. For Maki body, SmC, SmH tree, SmF book.

Chiral smecti books such as SmI and SmG' ...A liquid crystal composition having two phases can be used.

Table 1 shows specific examples of liquid crystals exhibiting a chiral smectic phase used in the liquid crystal composition of the present invention.

On the other hand, Table 2 shows specific examples of liquid crystals exhibiting a cholesteric phase.

Table 1 Specific examples of liquid crystals exhibiting a chilyle smectic phase (compound name, structural formula, and phase transition point) (1) CH3(
2) 0 sentences ■ - Chlorpropyl sinname) (HOBACPC) -
Methylbutyl-α-chlorocinnamate (OOBAMB
CC) CH30 -COOCH2CHC2H5 (MBRA 8) Table 2 Specific examples of liquid crystals exhibiting cholesteric phase (compound groups, structural formulas, and phase transition points) (A) Cholesteryl propionate (B)
Cholesteryl nonanate (C) Cholesteryl palmitate (D) Cholesteryl nonanate 4-(2''-methylbutyl)-4'-cyanobiphenyl--54°C SmA 4-- =xlzXte!Jy' phase '-3
0℃4-(2″′-methylbutyloxy)-4′-cyanobiphenyl＼
/26.5℃ Cholesteric phase 4-(2-methylbutyl)-4'-hexyloxyazobenzene 4-(2-methylbutyl)phenyl-4'-decyloxybenzoate 4-hexyloxy-4'-(2
-Methylbutyl)benzoate\Cholesteric phase 717°C Two or more of these liquid crystals exhibiting a chiral smectic phase or liquid crystals exhibiting a cholesteric phase may be used in combination.

The ratio of liquid crystal exhibiting a chiral smectic phase to liquid crystal exhibiting a cholesteric phase in the liquid crystal composition used in the present invention is as follows:
Although it differs depending on the type of liquid crystal used, it is generally 0.1 to 50 parts by weight, preferably 1 to 20 parts by weight, exhibiting a cholestic phase per 100 parts by weight of liquid crystal exhibiting a chiral smectic phase.

When constructing an element using these materials.

The liquid crystal composition becomes an SmC phase or an SmH* phase.

* In order to maintain this temperature, the element can be supported by a copper block with a heater embedded, etc., if necessary.

Figure 1 is used to explain the operation of a highly concentrated liquid crystal.

This is a schematic drawing of an example of a cell. 11 and 11'
I n203.5n02 or ITO (Indi
A substrate (glass plate) coated with a transparent electrode made of a thin film such as um-Tin Oxide), between which a liquid crystal molecular layer 12 is oriented perpendicularly to the glass surface.
mC.

Chiral smectic phase liquid crystals such as SmH, SmF, and SmI*SmG are sealed. A thick line 13 represents a liquid crystal molecule, and this liquid crystal molecule 1
3 has a dipole moment (P) 14 in the direction perpendicular to its molecule. 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 13 are aligned so that all the dipole moments (on P) 14 are directed 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 short axis direction,
Therefore, for example, if crossed Nicol polarizers are placed above and below a glass surface, a liquid crystal optical modulation element whose optical characteristics change depending on the polarity of applied voltage can be obtained.

easily understood.

The liquid crystal cell preferably used in the optical modulation element of the present invention can be made sufficiently thin (for example, 10 #L or less). As shown in the figure, even when no electric field is applied, the helical structure of the liquid crystal molecules unwinds and becomes a non-helical structure, and its dipole moment P or P' points upward (24)
or downward (24'). When an electric field E or E' with a different polarity, which is equal to or higher than a certain threshold value, is applied to such a cell by the voltage applying means 21 and 21' as shown in FIG. Corresponding to the vector, the liquid crystal molecules change direction upward 24 or downward 24', and accordingly the liquid crystal molecules enter the first stable state 2.
3 or the second stable state s23'.

As mentioned earlier, there are two advantages to using such ferroelectricity as an optical modulation element.

The Ml 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, when the electric field E is applied, the liquid crystal molecules are aligned in a first stable state 923, and this state remains stable even when the electric field is turned off. Furthermore, when an opposite electric field E' is applied, the liquid crystal molecules enter a second stable state 23.
′ and change the orientation of the molecule.

They remain in this state even when the electric field is turned off, and they remain in their respective orientation states as long as the applied electric field E does not exceed a certain threshold. In order to effectively realize such fast response speed and bistability, it is preferable that the cell be as thin as possible.

As mentioned above, the biggest problem in forming devices using liquid crystals with such ferroelectric properties is SmC, SmH', and SmF.

* A layer having a chiral smectic phase such as SmI or SmG was aligned perpendicularly to the substrate surface, and liquid crystal molecules were aligned approximately parallel to the substrate surface.

It is difficult to form cells with high monodomain properties, and the main purpose of the present invention is to provide a solution to this problem.

FIGS. 3A and 3B show an embodiment of a liquid crystal element according to the present invention. FIG. 3(A) is a plan view of a liquid crystal element according to the present invention, and FIG. 3(B) is a sectional view taken along line A- of the same.

In the cell structure 100 shown in FIG. 3, a pair of substrates 101 and IOT' made of a glass plate or a plastic plate are held at a predetermined distance by a spacer 104, and an adhesive 106 is used to seal the pair of substrates. It has a bonded cell structure, and furthermore, on the substrate lot, an electrode group (for example, a scanning voltage application electrode group of a matrix electrode structure) consisting of a plurality of transparent electrodes 102 is arranged in a predetermined pattern such as a strip pattern. It is formed of. Substrate 101'
An electrode group (for example, a signal voltage application electrode group in a matrix electrode structure) is formed on the transparent electrode 102 and a plurality of transparent electrodes 102' intersecting with each other.

The substrate 101' provided with such a transparent electrode 102' has
For example - silicon oxide, silicon 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, polyparaxylerin, polyester, polycarbonate,
polyvinyl acetal, polyvinyl chloride, polyamide,
The alignment control film 10'5 may be formed using an organic insulating material such as polystyrene, cellulose resin, melamine resin, urea resin, or acrylic resin.

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

In another preferred embodiment of the present invention, the alignment control film 105 can be obtained by coating an inorganic insulating material such as SiO or 5i02 on the substrate 101' by oblique vapor deposition.

In the apparatus shown in FIG. 5, the Pel jar 501 is placed on an insulating substrate 503 having a suction port 505 and is evacuated by a vacuum pump (not shown) extending from the suction port 505. . Crucible 507 made of tungstic acid or molybdenum is Pelger 50
A crucible 507 contains several grams of crystals 5 such as S io , S io2 , MgF2, etc.
08 is placed. The crucible 507 has two lower arms 507a, 507b, each of which has a conducting wire 50.
Connected to 9,51O. electric [506 and switch 50
4 is connected in series between external conductors 5C19 and 510 of Pelger 501. Substrate 502 is positioned inside Pelger 501 directly above crucible 507 at an angle θ with respect to the vertical axis of Pelger 501 .

When the switch 504 is opened, the Pel jar 501 is first evacuated to approximately 10-5 mmHg pressure, and then the switch 504 is closed and the power supply 506 is turned on until the crucible 507 becomes incandescent at a suitable temperature and the crystal 508 is evaporated. Power is supplied in a regulated manner. The current required for a suitable temperature range (700-1000″C) is approximately 100100A.Crystal 508
is then evaporated to form an upward molecular flow indicated by S in the figure, and the fluid S is incident on the substrate 502 at an angle of 0 with respect to the substrate 502, so that the substrate 502 is coated. Ru. The angle θ is the angle of incidence described above, and the direction of the fluid S is the “oblique deposition direction” described above. The thickness of this coating is determined by time-versus-thickness calibration of the apparatus before inserting the substrate 502 into the Pelger 501. When a coating of appropriate thickness is formed, the power from power source 506 is reduced and switch 504 is opened to cool Pelger 501 and its interior. Next, the pressure is increased to atmospheric pressure and the substrate 502 is removed from the Pelger 501.

In another specific example, after forming a film of the above-mentioned inorganic 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 doing so, an oriented MlII effect can be imparted to the surface.

It is preferable that the above-mentioned alignment control film 105 also functions as an insulating film at the same time.
The film thickness of No. 5 can be generally set in the range of 100 to 1 ml, preferably 500 to 5000 ml. This insulating film also has the advantage of being able to prevent the generation of current caused by trace amounts of impurities contained in the liquid crystal layer 103.
Therefore, even if the operation is repeated, the liquid crystal compound will not deteriorate.

Further, in the liquid crystal element of the present invention, a film similar to the above-described 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.
SmC, SmH, SmF trees.

It can be a chiral smectic phase such as wood wood* SmI, SmG*. The liquid crystal layer 103 exhibiting this chiral smectic phase undergoes a phase transition from another phase on the higher temperature side than the chiral smectic phase, such as the tomoyoshi phase or cholesteric phase, to the smectifuku A phase during the cooling process, and then to the chiral smectic phase during the cooling process. It is formed by a phase transition.

An important point in the present invention is that when a liquid crystal composition containing a liquid crystal exhibiting a cholesteric phase is used to cause a phase transition from a high temperature phase to SmA, the liquid crystal molecular axis of SmA is aligned in the alignment control direction given to the alignment control film 105. As a result, uniform monodomains are formed.

FIG. 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 10.1 and 1.
A plurality of spacer members 201 are arranged between 01'. This spacer member 201 is 1, for example, an orientation control M10.
SiO, Si
O2゜A sentence 203. Inorganic compounds such as TiO2, polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparaxylylene, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, urea resin acrylic It can be obtained by forming a film of resin such as resin or photoresist resin by an appropriate method, and then etching it so that the spacer member 201 is placed at a predetermined position.

In such a cell structure 10O, polarizers 107 and 108 in a crossed nicol state or a parallel nicol state are arranged on both sides of the substrates 101 and 101', respectively, and the electrode 1
Optical modulation will occur when a voltage is applied between 02 and 102'.

Next, regarding the method for manufacturing the liquid crystal element of the present invention, the liquid crystal layer 103
The orientation control method will be specifically explained using FIG. 3.

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

Next, the liquid crystal composition in the cell 100 is heated to a temperature at which the liquid crystal composition becomes an isotonic phase. Thereafter, the temperature of the heating case is lowered, and the liquid crystal composition in the isobic phase in the cell 100 is transferred to a cooling process. In this cooling process, the liquid crystal composition in the isopic phase is changed to SmA or Grandshuan structure. A phase transition can occur from the cholesteric phase to S m A. At this time, the liquid crystal molecular axes of SmA are aligned in the rubbing direction.

Thereafter, this SmA undergoes a phase transition to a chiral smectic phase in the process of cooling, thereby obtaining a chiral smectic phase such as monodomain S m C' having a non-helical structure, for example, when the cell thickness is set to about 14 m. - FIG. 6 is a schematic diagram of a cell 41 having a matrix electrode structure in which a ferroelectric liquid crystal compound is sandwiched between. 42 is a scanning electrode group, and 43 is a signal electrode group.

FIGS. 7(a) and 7(b) respectively show the electrical signals given to the selected scanning electrode 42 (s) and the electrical signals given to the other scanning electrodes (unselected scanning electrodes) 42 (n). , FIGS. 6(C) and (d) represent the electrical signal applied to the selected signal electrode 43(s) and the electrical signal applied to the unselected signal electrode 43(n), respectively, FIG. 7(&) In ~(d), the horizontal axis represents time and the vertical axis represents voltage. For example, when displaying a moving image, the scanning electrode group 42 is selected one cycle at a time. Now, if the threshold voltage for providing the first stable state of a liquid crystal cell having bistable property is vt hl, and the threshold voltage for providing the second stable state is −vt h2, then the selected trace.

The electrical signal given to the scanning electrode 42 (s) is as shown in FIG.
As shown in a), the voltage is alternating such that it is V in phase (time) tl and 1 in phase (time) t2. The other scanning electrodes 42(n) are shown in FIG. 7(b).
As shown in the figure, it is in a grounded state and the electrical signal is O. On the other hand, the electric signal given to the selected signal electrode 43(s) is V as shown in FIG. 7(C), and the electric signal given to the unselected signal electrode 43(n) is V as shown in FIG. As shown in d), at 0 or more where <-V,
The voltage V is set to a desired value that satisfies v<vthl<2V and -V>-Vth2>-2V. FIG. 8 shows the voltage waveforms applied to each pixel when such an electric signal is applied. FIGS. 8(a) to (d) represent pixels A, B, and C in FIG. and D. That is, as is clear from FIG. 8, a voltage of 2V exceeding the threshold value vtht is applied to the pixel A on the selected scanning line in one phase t2. Also, in pixel B existing on the same scanning line, the phase t
1, a voltage -2■ exceeding the threshold value -vth2 is applied.

Therefore, depending on whether a signal electrode is selected on the selected scanning electrode line, if the signal electrode is selected, the liquid crystal molecules are aligned in the first stable state, and if not selected, the liquid crystal molecules are aligned in the second stable state. Align the orientation to a stable state. In any case, it has nothing to do with the previous history of each pixel.

On the other hand, as shown in pixels C and D, in the unselected scanning line H, the voltage 41 applied to all pixels C and D is
+v or -■, 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. are doing. That is, when a scanning electrode is selected, signals for one line are written, and until the next frame is selected,
This means that the signal state can be maintained. Therefore, even if the number of scanning electrodes increases, the actual duty ratio does not change, and there is no reduction in contrast or crosstalk.In this case, as the voltage value V and the phase (tl + t2') = Although it depends on the liquid crystal material used and the thickness of the cell, it is usually 0.1 to 2 volts at 3 volts to 70 volts.
A range of m5e c is used. Therefore, in this case, the electrical signal applied to the selected scanning electrode changes from the first stable state S (assumed to be in the "bright" state when converted into an optical signal) to the second stable state S (assumed to be in the "bright" state when converted into an optical signal). "Dark" when converted
A change can occur either to the state (supposed to be a state) or vice versa.

SmC, SmH book, 5inF*, SmI book.

Liquid crystals exhibiting a chiral smectic phase (such as SmG)
DOBAMBC, HOBACPC.

When a liquid crystal composition containing a liquid crystal having a cholesteric phase used in the present invention is used in the present invention, an alignment state with good alignment properties and fewer alignment defects can be obtained compared to when a liquid crystal composition (such as MBRA8) is used alone.

Especially when the cell thickness is thin or bistability (memory property)
SmC, SmH book with.

Chiral books such as books SmF, SmI, SmC books, etc.
In the case of this smectic phase, the restraining force (effect of substrate alignment treatment) on liquid crystal molecules on the substrate surface is important 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 pm cell, when only one side substrate is subjected to alignment treatment, a response speed approximately twice as high as that obtained when both substrates are aligned is obtained.

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

〔Example! ]

A square glass substrate on which a striped ITO film with a pitch of 1004 m and a radius of 62.54 m was provided as an electrode was prepared, and the side with the ITO film serving as the electrode facing downward was subjected to oblique evaporation as shown in Fig. 5. It was set in the apparatus, and then a 5to2 crystal was set in a molybdenum crucible.

Thereafter, the inside of the vapor deposition apparatus was brought to a vacuum state of about 410-5 Torr, and 5i02 was obliquely vapor-deposited on the glass substrate by a predetermined method to form an obliquely vapor-deposited film of 800 people (electrode plate A).

On the other hand, a polyimide forming solution (rPIQ manufactured by Hitachi Chemical Co., Ltd. with a non-volatile content concentration of 14.5 wt%) was applied using a spinner coater onto a glass substrate on which a similar striped ITO film was formed. ℃ for 30 minutes, 200℃ for 60 minutes, and 350℃ for 30 minutes.
A film of 0.00 people was formed (B electrode plate).

Next, a thermosetting epoxy adhesive is applied to the periphery of the A electrode plate except for the injection hole by screen printing, and then the striped pattern electrodes of the A electrode plate and the B electrode plate are overlapped so that they are perpendicular to each other. , the distance between the two electrode plates is 21
It was maintained with a polyimide spacer so that it was L, and was made into a cell.

Next, P-desyloxybenzylidene-P'-7 minnow 2-
A liquid crystal composition was prepared by adding 5 parts by weight of cholesteryl nonanate to 100 parts by weight of methyl butyl cinnamate (DOBAMBC).

This liquid crystal composition was heated to form an isokyoshi phase, prepared as described above, and injected into the cell through the injection port, and the injection port was sealed. When this cell was cooled slowly and the temperature was maintained at approximately 70°C, a pair of polarizers was placed in a crossed Nicols state and observed under a microscope. It was confirmed that it was formed.

[Example 2] A polyimide forming solution (manufactured by Hitachi Chemical Co., Ltd. (7) r
PIQJ; non-volatile Je content: 11 degrees, 14.5 wt%) was applied using a spinner coater and heated at 120°C for 30 minutes, 200°C for 60 minutes, and 350°C for 30 minutes.
A film was formed for 00 people (A electrode plate).

Next, the polyimide coated electrode plate obtained in the same manner as above was rubbed with a cloth. (B electrode plate) Next, after applying thermosetting epoxy adhesive to the periphery of the A electrode plate except for the injection hole, the striped pattern electrodes of the A electrode plate and the B electrode plate are perpendicular to each other. The two electrode plates were stacked one on top of the other and held with a polyimide spacer so that the distance between the two electrode plates was two ends to form a cell.

4-(2-methylphthyl)phenyl-4'- to 100 parts by weight of P-decyloxybenzylidene-P'-amino-2-methylbutylcinnamate (DOBAMBC)
A liquid crystal composition was prepared by adding 10 parts by weight of desyloxybenzoate.

This liquid crystal composition was injected into the cell through the injection port, and the injection port was sealed.

When this cell was cooled slowly and the temperature was maintained at approximately 65°C, a pair of polarizers was placed in a crossed Nicol state and observed under a microscope, it was found that SmC'' with a monodomain spiral was formed. I was able to confirm that there is

[Brief explanation of drawings]

1 and 2 are perspective views showing a liquid crystal cell used in the present invention. FIG. 3(A) is a plan view showing the liquid crystal element of the present invention, and FIG. 3(B) is a sectional view taken along the line AN. Figure 4 is. There is a cross-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(1k) to 7(d) are explanatory diagrams showing signals for driving the liquid crystal element used in the present invention. 81st M (
a) to (d) are explanatory diagrams showing voltage waveforms applied to each pixel. 100; Cell structure 101.101', Substrate 102.102', Electrode 103; Liquid crystal layer 104.201'; Spacer member 105; Alignment control film 106; Adhesive 107.1.08, Polarizer 109; Heat generation Canon Corporation Figure 8 (d)

Claims (18)

[Claims] (1) A cell structure is formed in which a liquid crystal composition containing at least a liquid crystal exhibiting a chiral smectic phase and a liquid crystal exhibiting at least a cholesteric phase is sealed between a pair of substrates, and at least one of the pair of substrates 1. A liquid crystal element having an effect of preferentially arranging the molecular axes of the liquid crystal in one direction with respect to the directions of the molecular axes of the liquid crystal that the surfaces thereof contact at an interface. (2) The liquid crystal element according to claim 1, wherein the liquid crystal composition is a liquid crystal that sequentially undergoes a phase transition from a smectic A phase to a chiral smectic phase during a cooling process. (3) The chiral smectic phase is C phase, H phase, F phase
3. The liquid crystal element according to claim 2, which is in phase, I phase or G phase. (4) The liquid crystal element according to claim 2 or 3, wherein the chiral smectic phase has a non-helical structure. (5) 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 this effect. The liquid crystal element according to range 1. (6) Claim 1 or 5, wherein the surface having the effect is a surface obtained by rubbing the surface of the substrate.
The liquid crystal element described in . (7) The liquid crystal element according to claim 6, wherein the surface is a surface formed by a coating of an organic insulating material or an inorganic insulating material. (8) 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. 8. The liquid crystal element according to claim 7, wherein the resin is at least one selected from the resin group consisting of resin, acrylic resin, and photoresist resin. (9) The inorganic substance is SiO, SiO_2 or TiO_
2. The liquid crystal element according to claim 7, which is No. 2. (10) The liquid crystal element according to claim 1 or 5, wherein the surface having the effect is a surface obtained by diagonally depositing an insulating material on the surface of the substrate. (11) The liquid crystal element according to claim 10, wherein the insulating material is SiO or SiO_2. (12) The liquid crystal element according to claim 1 or 5, wherein the surface having the effect is a surface obtained by obliquely etching the surface of the substrate. (13) The liquid crystal element according to claim 12, wherein the surface is a surface formed of a film or a substrate of an organic or inorganic insulating material. (14) the organic insulating material is polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparaxylylene, polyester, polycarbonate,
Claim 13: The resin is at least one selected from the resin 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 . (15) The inorganic insulating material is glass, SiO, SiO_
14. The liquid crystal element according to claim 13, which is TiO_2 or TiO_2. (16) The liquid crystal element according to claim 2, wherein the other substrate is a substrate provided with a spacer member obtained by forming a film of an insulating material and then etching except for a predetermined position. (17) The liquid crystal element according to claim 16, wherein the spacer member is a band-shaped member. (18) The liquid crystal element according to claim 17, which is an element comprising a plurality of the band-shaped spacer members.