JPS6334452B2 - - Google Patents

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., and more particularly to a liquid crystal element with improved display and driving characteristics by improving the initial alignment state of liquid crystal molecules. Conventionally, liquid crystal display elements are well known in which a scanning electrode group and a signal electrode group are configured in a matrix, and a liquid crystal compound is filled between the electrodes to form a large number of pixels to display images or information. There is. 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. That is, it is difficult to increase the pixel density or enlarge the screen. Among conventional liquid crystals, most of them are actually used as display elements because they have a relatively high response speed and low power consumption.
“Voltage-Dependent Optical Activity of a
This type of liquid crystal uses a TN (twisted nematic) type liquid crystal shown in ``Twisted Nematic Liquid Crystal'', and this type of liquid crystal is made of nematic liquid crystal molecules that have positive dielectric anisotropy in the absence of an electric field. The molecules of this liquid crystal are aligned in parallel on both electrode surfaces.On the other hand, when an electric field is applied, a nematic structure with positive dielectric anisotropy is formed. The liquid crystals are aligned in the direction of the electric field, resulting in optical modulation. When this type of liquid crystal is used to construct a display element with a matrix electrode structure, the region where both the scanning electrode and the signal electrode are selected ( A voltage higher than the threshold required to align the liquid crystal molecules perpendicularly to the electrode surface is applied to the selected point (selected point), and no voltage is applied to the region where neither the scanning electrode nor the signal electrode is selected (non-selected point), Therefore, the liquid crystal molecules maintain a stable alignment parallel to the electrode plane. By placing linear polarizers in a cross-Nicol relationship above and below the liquid crystal cell, no light is transmitted at the selected point, and Since light passes through non-selected points, they can be used as image elements.However, if a matrix electrode structure is configured, scan electrodes are selected and signal electrodes are not selected in areas, or scan electrodes are selected. not,
Area where signal electrodes are selected (so-called “half-selected point”)
The electric field is also finitely strong. If the difference between the voltage applied to the selected point and the voltage applied to the half-selected point is sufficiently large, and the voltage threshold required to align the liquid crystal molecules perpendicular to the electric field is set to an intermediate voltage value, the display element will It works normally, but
When increasing the number of scanning lines N, the entire screen (1
The time during which an effective electric field is applied to one selected point (duty ratio) decreases at a rate of 1/N while scanning a frame. For this reason, when repeated scanning is performed, the effective voltage difference between selected points and non-selected points becomes smaller as the number of scanning lines increases, resulting in reduced image contrast and crosstalk. has become an unavoidable drawback.
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 essentially an unavoidable problem that arises when driving using the temporal accumulation effect (that is, repeatedly scanning). 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, looking at the field of printers, laser beam printers provide electrical image signals in the form of light to electrophotographic photoreceptors in terms of both pixel density and speed, as a means of obtaining hard copies using electrical signals as input. (LBP) is currently the best.
However, LBP has the following disadvantages: 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 dots/mm within a length of 210 mm, it is necessary to have more than 3000 signal generating sections. In order to provide independent signals to each, it was originally necessary to wire lead wires to send signals to all of the signal generating parts, 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. This is because the electrode for applying a signal can be shared by 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 1/N, and the amount of light obtained on the photoreceptor decreases. However, there is a problem of crosstalk, which has been reduced. The use of bistable liquid crystal elements is one way to improve these drawbacks of conventional liquid crystal elements.
Clark and Lagerwall (Japanese Unexamined Patent Publication No. 56-107216, US Pat. No. 4,367,924). Bistable liquid crystals generally include chiral smectate C phase (SmC ^* ) or other chiral smectate phases, specifically chiral smectate H phase (SmH ^* ), chiral smectate F phase (SmF ^* ), a chiral smectoid I phase (SmI ^* ), and a chiral smectoid G phase (SmG ^* ). This liquid crystal has a bistable state consisting of a first optically stable normal state and a second optically stable state with respect to an electric field, and is therefore different from the optical modulation element used in the above-mentioned TN type liquid crystal, for example. The liquid crystal is aligned in a first optically stable state with respect to one electric field vector,
The liquid crystal is oriented in a second optically stable state relative to the other electric field vector. In addition, this type of liquid crystal very quickly takes one of the two stable states in response to an applied electric field, and maintains that state when no electric field is applied.
Significant substantial improvements are obtained over many of the problems of conventional TN type devices mentioned above. This point is
The present invention will be described in more detail below. However, in order for an optical modulation element using this bistable liquid crystal to exhibit predetermined driving 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 stable states can occur effectively. For example SmC ^*
For ferroelectric liquid crystals with or other chiral smectic phases, the liquid crystal molecular layer with SmC ^* or other chiral smectic phases is perpendicular to the substrate plane, so that the liquid crystal molecular axes are aligned with the substrate plane. It is necessary to form regions (monodomains) arranged almost parallel to each other. However, in conventional optical modulators using bistable liquid crystals,
The actual situation is that the alignment state of liquid crystals having such a monodomain structure is not necessarily formed satisfactorily, and therefore sufficient characteristics cannot be obtained. For example, methods of applying a magnetic field, methods of applying shear force, etc. have been proposed in order 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 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 provide a bistable display device which has potential suitability as a display element having high-speed response, high-density pixels and a large area, or an optical shutter having a high shutter speed. An object of the present invention is to provide a method for controlling the alignment of liquid crystal that can fully exhibit its properties by improving monodomain formation or initial alignment, which has been a problem in the past in optical modulation elements using liquid crystals having . As a result of further research for the above-mentioned purpose, the present inventors focused their attention on the orientation in the cooling process in which the liquid crystal material transitions from another phase (for example, a high-temperature state such as an isotropic phase) to a low-temperature state of a smectic phase. As a result, during the cooling process, the isotropic phase changes to the cholesteric phase, the smectic A phase, the chiral smectic C phase, the chiral smectic H phase (SmH ^* ),
Chiral smectite F phase (SmF ^* ), chiral smectite I phase (SmI ^* ), chiral smectite J phase (SmJ ^* ), chiral smectite K phase (SmK ^* ), chiral smectite G phase (SmG ^* ), which undergoes a phase transition from an isotropic phase to a cholesteric phase and a chiral smectic phase during the cooling process with at least one type of liquid crystal (hereinafter referred to as liquid crystal A) that causes a phase transition to a chiral smectic phase. At least 1 liquid crystal (hereinafter referred to as liquid crystal B)
When a liquid crystal composition containing seeds is used, the liquid crystal molecules are aligned in one direction by giving the surface of the substrate that contacts 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. As a result, it is possible to obtain a liquid crystal element with 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, and also to maintain alignment stability over a long period of time. We have discovered that it can improve your sexual performance. Furthermore, the present inventors have created a liquid crystal composition in which a liquid crystal that undergoes a phase transition from an isotropic phase to a smectic A phase and a chiral smectic phase (hereinafter referred to as liquid crystal C) is added to the aforementioned liquid crystal composition. teeth,
It has been found that alignment stability performance over a longer period of time can be obtained than the above-mentioned liquid crystal compositions. Therefore, the present invention has a cell structure in which a liquid crystal composition containing the above-mentioned liquid crystal A and liquid crystal B, preferably liquid crystal C, is sealed, and the surface of at least one of the pair of substrates is in contact with the interface. It is characterized by having the effect of preferentially aligning the molecular axis direction of liquid crystal in one direction. 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. Specific examples of the aforementioned liquid crystal A, liquid crystal B, and liquid crystal C are shown in Table 1, Table 2, and Table 3, respectively.

[Table] --→ --→ --→
--→
Crystal SmC ^* SmA Cholesteric phase Isotropic phase
←―― ←―― ←――
←――

[Table] --→ --→
--→
Crystal SmC ^* Cholesteric phase
Isotropic phase ←―― ←――
←――

[Table] --→ --→
--→
Crystal SmC ^* Cholesteric phase
Isotropic phase ←―― ←――
←――

【table】

[Table] --→ --→ --→

Crystal SmC ^* SmA Isotropic phase
←―― ←―― ←――

Two or more of these liquid crystals A, B, and C may be used in combination. Liquid crystal A and liquid crystal B in the liquid crystal composition used in the present invention
The ratio of liquid crystal A to 1 part by weight of liquid crystal B varies depending on the type of liquid crystal used.
The amount is 0.05 to 20 parts by weight, preferably 0.5 to 2 parts by weight. In addition, the blending ratio of liquid crystal C in the liquid crystal composition is
0.1 to 40% by weight, preferably 5 to 20% by weight. When constructing an element using these materials, the liquid crystal composition may be SmC ^* , SmH ^* , SmF ^* , SmI ^* ,
In order to maintain the temperature at SmG ^* , the element can be supported by a steel block or the like with a heater embedded in it, if necessary. FIG. 1 schematically depicts a row of cells to explain the operation of a ferroelectric liquid crystal. 11 and 1
1′ is In ₂ O ₃ , SnO ₂ or ITO (Indium−Tin
It is a substrate (glass plate) coated with a transparent electrode made of a thin film such as
SmC ^* oriented so that 2 is perpendicular to the glass surface,
Chiral smectate phase liquid crystals such as SmH ^* , SmF ^* , SmI ^* , and SmG ^* are sealed. A thick line 13 represents a liquid crystal molecule, and this liquid crystal molecule 13 has a dipole moment (P⊥) 14 in a direction perpendicular to the 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 oriented so that all the dipole moments (P⊥) 14 are oriented in the direction of the electric field. 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, voltage can be applied. It is easily understood that this results in a liquid crystal optical modulation element whose optical properties change depending on the polarity. 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, the helical structure of the liquid crystal molecules unwinds and becomes a non-helical structure even when no electric field is applied, as shown in Figure 2, and its dipole moment P or P' is directed upward. 24 or downward 24'. In such a cell, the second
As shown in the figure, electric fields E with different polarities above a certain threshold value
or E' is applied by the voltage applying means 21 and 21', the dipole moment is directed upward 24 or downward 24', corresponding to the electric field vector of the electric field E or E'.
Accordingly, the liquid crystal molecules are oriented to either the first stable state 23 or the second stable state 23'. As mentioned earlier, there are two advantages to using such ferroelectricity as an optical modulation 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 with reference to FIG. 2, for example, when the electric field E is applied, the liquid crystal molecules are oriented in a first stable state 23, and this state remains stable even when the electric field is turned off. When an electric field E' in the opposite direction is applied, the liquid crystal molecules are oriented to a second stable state 23' and change their orientation, but they remain 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 problems in forming devices using liquid crystals with such ferroelectricity are SmC ^* , SmH ^* , SmF ^* , SmI ^* , and SmG ^*.
It is difficult to form a highly monodomain cell in which a layer having a chiral smectoid phase is aligned perpendicular to the substrate surface and liquid crystal molecules are aligned approximately parallel to the substrate surface. It is the main objective of the present invention to provide a solution to this point. FIGS. 3A and 3B show an embodiment of the liquid crystal element of the present invention. FIG. 3A is a plan view of the liquid crystal element of the present invention, and FIG. 3B is a sectional view taken along line A-A'. The cell structure 100 shown in FIG. 3 includes a pair of substrates 101 made of glass plates, plastic plates, etc.
and 101' are held at a predetermined distance by a spacer 104, and has a cell bonded with an adhesive 106 to seal the pair of substrates, and further includes a plurality of transparent electrodes 102 on the substrate 101. An electrode group (for example, an electrode group for applying a scanning voltage in a matrix electrode structure) is formed in a predetermined pattern such as a strip pattern. Substrate 10
1', there is an electrode group (for example,
Of the matrix electrode structure, a signal voltage application electrode group) is formed. A substrate 10 provided with such a transparent electrode 102'
1' includes, for example, inorganic insulating materials such as silicon monoxide, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide, and boron nitride, polyvinyl alcohol, and polyimide. ,
Orientation control film formed using organic insulating materials such as polyamideimide, polyesterimide, polyparaxylerin, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, and acrylic resin. membrane 105
can be provided. This 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 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 forming a film of an inorganic insulating material such as SiO or SiO ₂ on the substrate 101' by an oblique vapor deposition method. In the apparatus shown in FIG.
1 is placed on an insulating substrate 503 having a suction port 505, and the bell gear 501 is evacuated by a vacuum pump (not shown) extending from the suction port 505. A crucible 507 made of tungsten or molybdenum is placed inside and at the bottom of the bell jar 501, and the crucible 507 contains several grams of SiO,
A crystal 508 of SiO ₂ , MgF ₂ or the like is placed. The crucible 507 has two lower arms 507a, 50
7b, and the arms have conductive wires 509, 51, respectively.
Connected to 0. Power supply 506 and switch 504
are connected in series between the external conductors 509 and 510 of the bell jar 501. The board 502 is Bergier 5
Belgear 5 is located directly above crucible 507 inside 01.
01 at an angle θ with respect to the vertical axis. When the switch 504 is opened, the bell gear 5
01 is first evacuated to a pressure of about 10 ^-5 mmHg, and then the switch 504 is closed and power is supplied by adjusting the power source 506 until the crucible 507 becomes incandescent at a suitable temperature and the crystal 508 is evaporated. . The current required for the appropriate temperature range (700-1000℃) is approximately 100amps
It is. The crystal 508 is then evaporated to form an upward molecular stream indicated by S in the figure, and the fluid S is directed toward the substrate 5.
02 onto the substrate 502, resulting in coating of the substrate 502. The angle θ is the above-mentioned "incident angle", and the direction of the fluid S is the above-mentioned "oblique deposition direction". The thickness of this coating is determined by a time-based thickness calibration of the apparatus prior to inserting the substrate 502 into the bell gear 501. When a coating of appropriate thickness is formed, the power from power source 506 is reduced and switch 504 is opened to cool bell jar 501 and its interior. Next, the pressure is increased to atmospheric pressure and the substrate 5
02 from the bell jar 501. In another specific example, the surface of the substrate 101' made of glass or plastic, or the surface of the substrate 101' made of glass or plastic.
By forming a film of the above-mentioned inorganic insulating material or organic insulating material on 1', and then etching the surface of the film by an oblique etching method, an orientation control effect can be imparted to the surface. The above-mentioned orientation control film 105 preferably functions as an insulating film at the same time, and for this reason, the film thickness of this orientation control film 105 can be generally set in the range of 100 Å to 1 μ, preferably 500 Å to 5000 Å. . 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, 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-described alignment control film 105 can be provided on the other substrate 101. Liquid crystal layer 1 in cell structure 100 shown in FIG.
03 is SmC ^* , SmH ^* , SmF ^* , SmI ^* , SmG ^*
It can be a chiral smectic phase such as. This chiral smect liquid crystal layer 103
contains liquid crystal A and liquid crystal B, more preferably liquid crystal C. An important point in the present invention 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 smectate phase or a chiral smectate phase, the liquid crystal molecular axis is 105
As a result, uniform monodomains are formed, and no disturbance in orientation occurs even during long-term storage. FIG. 4 shows another specific example of the liquid crystal element of the present invention. The liquid crystal element shown in FIG. 4 includes a plurality of spacer members 2 between a pair of substrates 101 and 101'.
01 is placed. This spacer member 201
For example, an inorganic compound such as SiO, SiO ₂ , Al ₂ O ₃ , TiO ₂ or polyvinyl alcohol,
Polyimide, polyamideimide, polyesterimide, polyparaxylylene, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin, photoresist resin, and other resins This can be obtained by forming a film using an appropriate method and then etching it so that the spacer member 201 is placed at a predetermined position. Such a cell structure 100 has a substrate 101 and a
Polarizers 107 and 108 in a crossed Nicol state or a parallel Nicol state are arranged on both sides of electrode 01', respectively, and optical modulation occurs when a voltage is applied between electrodes 102 and 102'. Next, regarding the method for manufacturing the liquid crystal element of the present invention, a method for controlling the orientation of the liquid crystal layer 103 will be specifically explained using FIG. First, the cell structure 100 in which the liquid crystal composition is sealed is set in a heating case (not shown) that uniformly heats the entire cell 100. Next, the liquid crystal composition in the cell 100 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. FIGS. 7a and 7b show the electrical signals applied to the selected scan electrode 42(s) and the other scan electrodes (unselected scan electrodes) 42, respectively.
(n), and FIGS. 6c and 6d show the electrical signals applied to the selected signal electrode 43(s) and the unselected signal electrode 43, respectively.
(n) represents an electrical signal given to Figure 7a
-d, 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, let Vth ₁ be the threshold voltage for providing the first stable state of a liquid crystal cell having bistability, and −Vth ₂ be the threshold voltage for providing the second stable state.
Then, the electrical signal applied to the selected scanning electrode 42(s) is V at phase (time) t ₁ and −V at phase (time) t ₂ , as shown in FIG. 7a.
It is an alternating voltage such that Further, the other scanning electrodes 42(n) are in a grounded state as shown in FIG. 7b, and have an electric signal O. On the other hand, the electric signal applied to the selected signal electrode 43(s) is V as shown in FIG. 7c, and the electric signal applied to the unselected signal electrode 43(n) is shown in FIG. 7d. It is -V as shown. In the above, the voltage V is set to a desired value that satisfies V<Vth ₁ <2V and -V>-Vth ₂ >-2V. FIG. 8 shows the voltage waveform applied to each pixel when such an electric signal is applied. 8a to 8d correspond to pixels A, B, C, and D in FIG. 6, respectively. That is, as is clear from FIG. 8, a voltage of 2V exceeding the threshold value _Vth1 is applied to the pixel A on the selected scanning line at phase _t2 . In addition, for pixel B existing on the same scanning line, the threshold value -Vth ₂ at phase t ₁
A voltage exceeding -2V 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, on unselected scanning lines, the voltages applied to all pixels C and D are +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 is written, and that signal state can be maintained until the next selection after one frame ends. Therefore, even if the number of scanning electrodes increases, the actual duty ratio does not change, and contrast reduction and crosstalk do not occur at all. At this time, the value of the voltage value V and the value of the phase (t ₁ + t ₂ )=T depend on the liquid crystal material used and the thickness of the cell, but are usually 3 volts to 70 volts.
A range of 0.1 μsec to 2 msec in volts 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). A change can also occur either to the "dark" state when The aforementioned SmC ^* , SmH ^* ,
Compared to the case where a liquid crystal exhibiting a chiral smectate phase such as SmF ^* , SmI ^* , SmG ^* is used alone, the use of the liquid crystal composition used in the present invention provides an alignment state with good alignment and fewer alignment defects. can get. Especially when the cell thickness is thin, or when the cell is bistable (memory), SmC ^* , SmH ^* , SmF ^* , SmI ^* ,
In the case of a chiral smectate phase such as SmG ^* , in terms of switching characteristics (response speed), it is preferable that the restraining force (effect of substrate alignment treatment) on liquid crystal molecules on the substrate surface be weaker. When only the substrate surface is subjected to alignment treatment, a faster response speed can be obtained than when alignment treatment is performed on both sides of the substrate surface. At this time, in a cell with a cell thickness of 2 μm, a response speed that is approximately twice as fast can be obtained when only one substrate is subjected to an orientation treatment as compared to a response speed when both substrates are subjected to an orientation treatment. Hereinafter, the present invention will be explained according to examples. Examples 1a and 1b Stripes with a pitch of 100 μm and a width of 62.5 μm
A square glass substrate provided with an ITO film as an electrode was prepared and set in the oblique evaporation apparatus shown in Fig. 5 with the side on which the ITO film serving as the electrode was provided facing downward, and then SiO2 was placed in a molybdenum crucible. ₂ crystals were set. After that, inside the vapor deposition equipment
After creating a vacuum state of about 10 ^-5 Torr, SiO ₂ was obliquely vapor-deposited on the glass substrate by a predetermined method to form an obliquely-deposited film of 800 Å (electrode plate A). On the other hand, a polyimide forming solution ("PIQ" manufactured by Hitachi Chemical Co., Ltd.; non-volatile content concentration 14.5 wt%) was applied using a spinner coater onto a glass substrate on which a similar striped ITO film was formed, and the temperature was increased to 120°C. for 30 minutes at 200℃
800℃ for 60 minutes and 30 minutes at 350℃.
A film with a thickness of 1.5 Å was formed (B electrode plate). Next, a thermosetting epoxy adhesive was applied to the periphery of the A electrode plate except for the area that would become the injection port using a screen printing method, and then the striped pattern electrodes of the A electrode plate and the B electrode plate were arranged so that they were perpendicular to each other. The two electrode plates were stacked together and maintained with polyimide spacers so that the distance between the two electrode plates was 2μ to form a cell. Next, 4-(2'-methylbutyl)phenyl-4'-
For 100 parts by weight of octyloxybiphenyl-4-carboxylate, 4-hexyloxyphenyl-4-(2″-methylbutyl)biphenyl-
A liquid crystal composition was prepared by adding 75 parts by weight of 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 lowering the temperature of this cell by slow cooling, a pair of polarizers were placed in a crossed nicol state, and microscopic observation confirmed that SmC ^* with a monodomain non-helical structure was formed ( Example 1a). Furthermore, after maintaining this liquid crystal element in the SmC ^* state for 700 hours, similar microscopic observation was performed again, and it was confirmed that it was still SmC ^* with a monodomain non-helical structure. As a comparative example, 4-(2'-methylbutyl)phenyl-4'-octyloxybiphenyl-4-carboxylate was used alone in place of the liquid crystal composition used in the cell in Example 1a. A cell was prepared in the same manner as in Example 1a (Comparative Example 1), and 4-hexyloxyphenyl-
Example 1a except that 4-(2″-methylbutyl)biphenyl-4′-carboxylate was used alone.
A cell was created in the same manner as (Comparative Example 2). In addition, the liquid crystal composition 100 used in Example 1a above
A liquid crystal composition was prepared by adding 20 parts by weight of DOBAMBC to the parts by weight, and a cell was created using this composition in the same manner as described above. When microscopic observation was performed, it was found that even in the initial stage, SmC ^* with a monodomain non-helical structure was formed, and monodomain SmC ^* was also formed even after the durability test was extended by 1000 hours compared to the case of the above-mentioned example. Example 1b). Next, the degree of bistability in the cells under the SmC ^* state prepared in Examples 1a and 1b and Comparative Examples 1 and 2 was measured. Polarizing microscope with 100x magnification (product name: BH-2;
A cell under the SmC ^* state was set in a cell (manufactured by Olympus Optical Industry Co., Ltd.), the electrode of the A electrode plate in the cell was connected to the ground, and a positive polarity pulse was applied to the electrode of the B electrode plate (voltage value = 10 volts; Pulse width = 1 msec) or negative polarity pulse (voltage value = -10 volts; pulse width = 1 m
The amount of transmitted light after applying sec) was measured using a photomultiplier (manufactured by Hamamatsu Photonics Co., Ltd.; trade name: Photomultitube R761), and the output voltage B ₂ (mV) when negative polarity pulses were applied was measured. Ratio of the output voltage B ₁ (mV) when applying a negative pulse B ₁ /B ₂ =
I found B ₀ . Furthermore, the ratio A ₁ /A ₂ =A ₀ of the photomultiplier output voltage _{A 1} (mV) after applying the positive polarity pulse to the photomultiplier output voltage A 2 (mV) after applying the negative polarity pulse described above is determined,
Ratio during pulse application B Ratio after pulse application to ₀
The degree of bistability was determined by determining the ratio of A ₀ , A ₀ /B ₀ . The results are shown in Table 1. The larger the ratio A ₀ /B ₀ is, the better the degree of bistability is. At this time, the above-mentioned crossed nicols of the polarizing microscope were set so that the darkest state was produced when a negative polarity pulse was applied.

[Table] In the table, A ₁ is the output voltage after applying a positive polarity pulse (mV) A ₂ is the output voltage after applying a negative polarity pulse (mV) A ₀ is the contrast in the bistable state after applying the pulse B ₁ is the positive polarity B ₂ is the output voltage (mV) when a negative pulse is applied, B ₀ is the contrast in a bistable state when a pulse is applied, and the same applies to the following examples.
Further, the above-mentioned output voltage (mV) is the output voltage of the photomultiplier. Examples 2a and 2b Stripes with a pitch of 100 μm and a width of 62.5 μm
A polyimide forming solution (“PIQ” manufactured by Hitachi Chemical Co., Ltd.; non-volatile content concentration 14.5 wt%) was coated on a square glass substrate with an ITO film as an electrode using a spinner coater, and then heated at 120°C for 30 minutes for 200 min. Heating was performed at 350°C for 60 minutes and then at 350°C for 30 minutes to form a film of 800 Å (electrode plate A). Next, the polyimide coated electrode plate obtained in the same manner as above was subjected to a rubbing treatment with a cloth. (B electrode plate) Next, after applying a thermosetting epoxy adhesive to the periphery of the A electrode plate except for the area that will become the injection port by screen printing, the striped pattern electrodes of the A electrode plate and the B electrode plate are formed. The two electrode plates were stacked so that they were perpendicular to each other, and held with a polyimide spacer so that the distance between the two electrode plates was 2μ to form a cell. 4-octyloxyphenyl-4 per 100 parts by weight of 4-heptylphenyl-4-(4″-methylhexyl)biphenyl-4′-carboxylate.
A liquid crystal composition was prepared by adding 70 parts by weight of -(2″-methylbutyl)biphenyl-4′-carboxylate.This liquid crystal composition was heated to form an isotropic phase and injected from the injection port into the cell. The injection port was sealed.
After lowering the temperature of this cell by slow cooling, a pair of polarizers were placed in a crossed nicol state, and microscopic observation revealed that a monodomain non-helical structure was observed.
It was confirmed that SmC ^* was formed (Example 2a). Furthermore, after maintaining this liquid crystal element in the SmC ^* state for 700 hours, similar microscopic observation was performed again, and it was confirmed that it was still SmC ^* with a monodomain non-helical structure. As a comparative example, 4-pentylphenyl-4-(4″-methylhexyl)biphenyl-
A cell was prepared in the same manner as in Example 2a, except that 4′-carboxylate was used alone (Comparative Example 3)
and further 4-octyloxyphenyl-4-
A cell was prepared in the same manner as in Example 2a (Comparative Example 4) except that (2″-methylbutyl)biphenyl-4′-carboxylate was used alone. In addition, the liquid crystal composition used in Example 2a above was used. 100 things
A liquid crystal composition was prepared by adding 20 parts by weight of DOBAMBC to the parts by weight, and a cell was created using this composition in the same manner as described above. When microscopic observation was performed, it was found that even in the initial stage, SmC ^* with a monodomain non-helical structure was formed, and monodomain SmC ^* was also formed even after the durability test was extended by 1000 hours compared to the case of the above-mentioned example. Example 2b). Next, Examples 2a and 2b and Comparative Examples 3 and 4
The degree of bistability under the SmC ^* state prepared in Example 1 was evaluated by measuring the ratio A ₀ /B ₀ in the same manner as in Example 1 described above. The results are shown in Table 2.

[Table] Examples 3 and 4 Instead of 4-(2'-methylbutyl)phenyl-4'-octyloxybiphenyl-4-carboxylate used in Example 1, 4-pentylphenyl-4-(4 ″-methylhexyl)biphenyl-4′-
Liquid crystals were prepared in the same manner as in Example 1, except that carboxylate (Example 3) and p-n-octyloxybenzoic acid-p'-(2-methylbutyloxy)phenyl ester (Example 4) were used. When the device was observed under a microscope after it was created, it was found that SmC ^* had a monodomain non-helical structure. moreover,
When each example was subjected to a 700-hour durability test similar to Example 2, it was found that monodomain
It was confirmed that it was SmC ^* . Furthermore, when a liquid crystal element was made in the same manner as described above except that HOBACPC was used instead of DOBAMBC used in Example 1, and the same test was conducted, it was found that neither of Examples 3 and 4 In the initial stage and after 1700 hours of durability, monodomain
SmC ^* was confirmed. Examples 5a and 5b A solution with the following composition (solution composition (1)) and heated to 120℃ for 30 minutes.
A thin film was formed by drying for several minutes. Solution composition (1) Acetomethoxyaluminum diisopropylate polyester resin (Toyobo; Bylon 30P) 0.5 g Tetrahydrofuran 100 ml Next, the rubbed plastic substrates were rubbed in one direction under a pressure of 100 g/cm ² , and the rubbed pair of plastic substrates was Overlap so that the rubbing directions are parallel,
The part that would serve as the injection port was removed. The area around it was sealed. At this time, the distance between the pair of plastic substrates was 1 μ. Next, 4-(2'-methylbutyl)phenyl-
4-hexyloxyphenyl-4-(2″-methylbutyl)biphenyl- per 100 parts by weight of 4′-octyloxybiphenyl-4-carboxylate
A liquid crystal composition was prepared by adding 80 parts by weight of 4'-carboxylate. This liquid crystal composition was heated to form an isotropic phase, prepared as described above, and injected into the cell through the injection port under reduced pressure, and the injection port was sealed. After lowering the temperature of this cell by slow cooling, a pair of polarizers were placed in a crossed nicol state, and microscopic observation confirmed that SmC ^* with a monodomain non-helical structure was formed ( Example 5a). Furthermore, after maintaining this liquid crystal element in the SmC ^* state for 500 hours, similar microscopic observation was performed again, and it was confirmed that it was still SmC ^* with a monodomain non-helical structure. As a comparative example, 4-(2'-methylbutyl)phenyl-4'-octyloxybiphenyl-4-carboxylate was used alone in place of the liquid crystal composition used in the cell in Example 5a. A cell was prepared in the same manner as in Example 5a (Comparative Example 5), and 4-hexyloxyphenyl-
Example 5a except that 4-(2″-methylbutyl)biphenyl-4′-carboxylate was used alone.
A cell was created in the same manner as (Comparative Example 6). Moreover, the liquid crystal composition 100 used in the above-mentioned Example 5a
A liquid crystal composition was prepared by adding 20 parts by weight of OOBAMBCC to the parts by weight, and a cell was made using this composition in the same manner as described above. When observed under a microscope, it was found that even in the initial stage, SmC ^* with a monodomain non-helical structure was formed, and monodomain SmC ^* was also formed even after the durability test was extended by 800 hours compared to the case of the above-mentioned example. Example 5b). Next, Examples 5a and 5b and Comparative Examples 5 and 6
The degree of bistability under the SmC ^* state prepared in Example 1 was evaluated by measuring the ratio A ₀ /B ₀ in the same manner as in Example 1 described above. The results are shown in Table 3.

[Table] Examples 6 and 7 Instead of 4-(2'-methylbutyl)phenyl-4'-octyloxybiphenyl-4-carboxylate used in Example 5, 4-pentylphenyl-4-(4 ″-methylhexyl)biphenyl-4′-
Liquid crystals were prepared in the same manner as in Example 5, except that carboxylate (Example 6) and p-n-octyloxybenzoic acid-p'-(2-methylbutyloxy)phenyl ester (Example 7) were used. When the device was observed under a microscope after it was created, it was found that SmC ^* had a monodomain non-helical structure. moreover,
When each example was subjected to a 700-hour durability test similar to Example 2, it was found that monodomain
It was confirmed that it was SmC ^* . Furthermore, when a liquid crystal element was made in the same manner as described above, except that DOBAMBC was used instead of OOBAMBCC used in Example 5, and the same test was conducted, it was found that neither of Examples 5 and 7 Monodomain SmC ^* was confirmed at the initial stage and at the stage after 2000 hours of durability. Examples 8 and 9 4-pentylphenyl-4- used in Example 2
(4″-methylhexyl)biphenyl-4′-carboxylate instead of 4-(2′-methylbutyl)
Phenyl-4'-octyloxybiphenyl-4-
Liquid crystals were prepared in the same manner as in Example 2, except that carboxylate (Example 8) and p-n-octyloxybenzoic acid-p'-(2-methylbutyloxy)phenyl ester (Example 9) were used. When the device was observed under a microscope after it was created, it was found that SmC ^* had a monodomain non-helical structure. moreover,
When each example was subjected to a 700-hour durability test similar to Example 2, it was found that monodomain
It was confirmed that it was SmC ^* . Furthermore, when a liquid crystal element was made in the same manner as described above except that MBRA8 was used instead of DOBAMBC used in Example 2, and the same test was conducted, it was found that neither of Examples 3 and 4 In the initial stage and after 1500 hours of durability, monodomain
SmC ^* was confirmed.

[Brief explanation of the drawing]

1 and 2 are perspective views showing a liquid crystal cell used in the present invention. FIG. 3A is a plan view showing the liquid crystal element of the present invention, and FIG. 3B is a plan view of the liquid crystal element of the present invention.
It is an A′ cross-sectional view. 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. 7a to 7d are explanatory diagrams showing signals for driving the liquid crystal element used in the present invention. FIGS. 8a to 8d 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
...Orientation control film, 106...Adhesive, 107,1
08... Deflector, 109... Heating element.

Claims (1)

[Scope of Claims] 1. A pair of substrates in which at least one of the substrates is subjected to alignment treatment such that the axes of liquid crystal molecules are oriented in one direction in the projection component of the substrate, and a cholesteric phase, a smectate A phase, and a chiral smectate phase. and at least one kind of second liquid crystal that produces a cholesteric phase and a chiral smectic phase but does not produce a smectic A phase, based on 1 part by weight of the second liquid crystal. A chiral smectoid liquid crystal containing a first liquid crystal in a proportion of 0.05 to 20 parts by weight, which is disposed between the pair of substrates set at a spacing that can suppress the formation of a helix in the chiral smectic phase. , and a chiral smectate liquid crystal that is oriented in one of two different stable orientation states in the absence of an electric field by causing a phase transition to the chiral smectate phase by lowering the temperature from a phase on the higher temperature side than the smectate phase. and means for applying an electric field perpendicular to the substrate surface and strong enough to transition from one of the two different stable orientation states to the other. Tsuku liquid crystal element.