JP2603308B2 - Chiral smectic liquid crystal device and manufacturing method - Google Patents

Description

The present invention relates to a liquid crystal device used for a liquid crystal display or a liquid crystal-optical shutter, and more particularly to a liquid crystal device using a ferroelectric liquid crystal. The present invention relates to a liquid crystal device which has remarkably improved, has improved durability of the device, and has improved contrast between a dark state and a bright state.

(Background technology)

NA Clark et al. Have proposed a display device of a type that controls transmitted light in combination with a polarizing element by utilizing the refractive index anisotropy of ferroelectric liquid crystal molecules (Japanese Patent Application Laid-Open No. 56-1981).
No. 107216, U.S. Pat. No. 4,367,924, etc.). The ferroelectric liquid crystal generally has a chiral smectic C phase (SmC ^* ) or an H phase (SmH ^* ) in a specific temperature range, and generates a helical array structure in a bulk state. In response to an applied electric field, the liquid crystal at the phase temperature is placed in a bistable alignment state obtained by disposing the liquid crystal at a distance between a pair of substrates set at a distance small enough to suppress the formation of a helical alignment structure. It has a memory characteristic that takes one of the first optically stable state and the second optically stable state and maintains the state when no electric field is applied, and has a high-speed response characteristic to changes in the electric field. It is expected to be widely used as a high temperature and storage type display element.

In order for an optical modulator using a ferroelectric smectic liquid crystal having this bistable alignment state to exhibit the aforementioned memory characteristics and high-speed response characteristics as a product, the bistable alignment state must exist stably and uniformly. In addition, it is necessary that the device has excellent durability and a high contrast ratio between a bright state and a dark state.

Okada et al., In USP 4639089, applied a ferroelectric smectic liquid crystal having a temperature range in which a cholesteric phase occurs to a liquid crystal element having a uniaxial alignment treatment axis given by rubbing treatment, oblique deposition treatment, etc. It is clear that a ferroelectric smectic liquid crystal device in a bistable alignment state has been realized.

A ferroelectric smectic liquid crystal device with a uniform bistable alignment state realized by rubbing or oblique evaporation processing
In some cases, the amount of transmitted light under a bright memory was smaller than that of NA Clark et al.

In the above-mentioned ferroelectric smectic liquid crystal element in the bistable alignment state, the liquid crystal molecules are arranged with a high degree of order because the alignment state is uniform. The arrangement state of the liquid crystal molecules having a high degree of order has a fragile property against a stress from the outside of the cell, for example, an impact force or a strain force, and when such a force is applied, the arrangement state of the liquid crystal molecules is disturbed. And typically produces a sanded stalk. The occurrence of sanded texture due to impact force,
For example, it was revealed in USP4674839 by Tsuboyama et al.

By adopting a rubbing treatment method or an oblique deposition treatment method as an orientation treatment method, the present inventors have obtained a bistable orientation state having an arrangement state with a high degree of order, and also have a method of applying stress from outside the cell. On the other hand, an orientation state showing strong stability was found.

[Summary of the Invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a ferroelectric smectic liquid crystal element having a uniform bistable alignment state exhibiting strong stability against impact or distortion.

It is another object of the present invention to provide a ferroelectric smectic liquid crystal element in a uniform bistable alignment state having a large contrast between a bright state and a dark state.

According to the present invention, a. A pair of substrates subjected to a uniaxial orientation treatment, b. A chiral smectic C disposed between the pair of substrates
A chiral smectic liquid crystal having a bistable alignment state different between a high temperature side and a low temperature side in a phase, wherein the chiral smectic liquid crystal has an alignment state at a low temperature side, and c. Optically identifying the bistable alignment state A chiral smectic liquid crystal device comprising:

Further, according to the present invention, there are provided: a pair of substrates subjected to a uniaxial orientation treatment; b. A chiral smectic liquid crystal capable of generating two different states of a tendency to generate a pair of coupled hairpin defects and lightening defects. A chiral smectic liquid crystal having an alignment state indicating a generation order in which a lightning defect is generated in front of the uniaxial alignment process and a hairpin defect is generated in the rear, and c. In order to optically distinguish the two different states. The present invention provides a chiral smectic liquid crystal device comprising:

(Detailed description of embodiments of the invention)

FIG. 1 schematically illustrates an example of the ferroelectric liquid crystal cell of the present invention.

11a and 11b are In ₂ O ₃ and ITO (Indium Tin Oxid
e) a substrate (glass plate) covered with transparent electrodes 12a and 12b, etc., on which insulating films 13a and 13
b (SiO ₂ film, TiO ₂ film, Ta ₂ O ₅ film, etc.) and alignment control films 14 a and 14 b each formed of polyimide, polyamide, polyester or the like and having a thickness of 50 to 1000 mm are laminated.

At this time, they are parallel and in the same direction (direction A in FIG. 1).
Rubbed (in the direction of the arrow) to give an alignment film 14
a and 14b are arranged. A ferroelectric smectic liquid crystal 15 is disposed between the substrates 11a and 11b, and the distance between the substrates 11a and 11b is sufficient to suppress the formation of a helical array structure of the ferroelectric smectic liquid crystal 15. When the distance is set to a small distance (for example, 0.1 μm to 3 μm), the ferroelectric smectic liquid crystal 15 has a bistable alignment state. The above-described sufficiently small distance is held by bead spacers 16 (silica beads, alumina beads) arranged between the substrates 11a and 11b.

In this cell, two polarizers 17a and 17b are arranged in crossed Nicols in order to optically identify the alignment modulation of the liquid crystal molecules.

According to the experiments performed by the present inventors, the use of the liquid crystal material and the alignment control film clarified in the examples described below makes it possible to obtain the bistable state which occurs on the high temperature side and the low temperature side in the temperature range of the chiral smectic C phase. It was found that the crystalline orientation states were different, and the bistable orientation state on the low temperature side showed strong stability against impact or strain, and showed a large contrast between the bright state and the dark state. The ferroelectric smectic liquid crystal in the bistable alignment state at the low temperature side is projected onto the substrate surface in the rubbing direction (the tilt direction (arrow direction) of the liquid crystal molecules having a pretilt angle θpr as shown in FIG. 7). Direction), a lightning defect is generated in front and a hairpin defect is generated in the rear. The resulting alignment state. Hereinafter, in the temperature range of the chiral smectic C phase, for convenience, the above-described orientation state on the high temperature side is referred to as “C1 orientation”, and the orientation state on the low temperature side is referred to as “C2 orientation”.
Here, the expression “for convenience” is used because two different orientation states do not depend only on the temperature as described later.

FIG. 2 is a sketch of Reference Photo 1 (magnification: 10 × 10 ×), FIG. 3 is a sketch of Reference Photo 2 (magnification: 10 × 10), and FIG. 4 is Reference 3 (magnification: FIG. 5 is a sketch of Reference Photo 4 (magnification: 10 × 10), and FIG. 6 is a sketch of Reference Photo 5 (magnification: 10 × 10). . FIG. 2 shows a state of C1 orientation, FIG. 6 shows a state of C2 orientation, and FIGS. 3 to 5 show a generation order of generating a lightning defect in front and a hairpin defect in rear according to the rubbing direction. A mixed state of an alignment state and an alignment state that generates a generation order in which a hairpin defect occurs in front and a lightning defect occurs in the rear according to the rubbing direction (hereinafter, referred to as “C1 / C2 mixed alignment”) is shown. 2 to 6 show the state at the extinction position (the darkest position under 90 ° crossed Nicols).

According to the observations made by the present inventors, the area occupied by the CI alignment domains 20 shown in FIGS. 2 to 5 was also large predominantly.

The most recently used liquid crystal material is "CS-1014" (trade name) which is a ferroelectric smectic liquid crystal manufactured by Chitso Corporation.
As the orientation control film, "Sunever 150" (trade name), which is an alicyclic polyimide film forming solution manufactured by Nissan Chemical Industries, Ltd., was used. The rubbing treatment was performed in parallel to the upper and lower substrates and in the same processing direction, and the distance between the upper and lower substrates was set to a distance of 1.5 μm (details will be described in Example 1 below). The phase transition temperatures in this cell were as follows.

ISO; isotropic phase Ch; cholesteric phase SmA; smectic A phase Sm ^* C1; phase in C1 orientation state among chiral smectic C phases Sm ^* C1 / C2; C1 / C2 mixed orientation in chiral smectic C phase Phase Sm ^* C2; chiral smectic C phase of C2 orientation phase Cry; crystalline phase Iso-Ch phase transition point, Ch-SmA phase transition point, SmA-Sm ^* C1 phase transition point and Sm ^* C2 -Cry, phase transition point is a temperature measured by "FP800 temperature controller" (trade name) manufactured by Mettler, Switzerland, and is Sm ^* C1-Sm ^* C1 / C2 phase transition point and Sm ^* C1 / C2-Sm.
^{* The} C2 phase transition point is the temperature determined by microscopic observation at a reduced temperature.

According to FIG. 2, the extinction position of the C1 alignment domain 20 (the position of 90 ° crossed Nicols at which the dark state is set to the darkest) is the blue state, ie, the blue light state 21 and the blue dark state 22. Exists. According to FIG. 6, the extinction position of the C2 alignment domain 30 is a black state, and there are a white bright state 31 and a black dark state 32. According to FIGS. 3 to 5, the C1 alignment domain 20 having a blue extinction position and the C2 alignment domain having a black extinction position are shown.
It is clear that 30 and 30 are mixed. Also, C1
Under each state of the alignment domain 20, the C2 alignment domain 30, and the C1 / C2 mixed alignment domain 40, after applying a pulse of 50 μsec, +30 V, the state in the extinction position was observed.
The extinction position of the C1 alignment domain 20 is blue, and the C2 alignment domain 30 is blue.
Was black. Furthermore, C1 orientation domain 20, C
Under the respective states of the 2 orientation domain 30 and the C1 / C2 mixed orientation domain 40, after applying a 50 μsec, −30 V inversion pulse, and observing the state at the extinction position, the extinction position of the C1 orientation domain 20 was also found. It was blue and the extinction position of the C2 alignment domain 30 was black.

From the above experiments, it was found that the C1 alignment domains having different alignment states in the temperature range of the chiral smectic C phase.
It has a phase of 20 and C2 orientation domain 30, and it was found that the C2 orientation domain 30 gradually grows at a lower temperature, and the C1 orientation domain 20 becomes predominantly large so as to be negligible. 60% or more C2 oriented domain 30 to the domain
Occupied area). Further, as will be apparent from the examples described below, the ferroelectric smectic liquid crystal devices in the bistable alignment state occupying almost the C2 alignment domain 30 are those under the C1 alignment domain 20 and those in the conventional bistable alignment state (up and down). (A state of alignment caused by applying rubbing treatments in parallel to the substrate and in the opposite directions to each other). Stronger stability against impact force and strain force from the outside and greater contrast between the bright state and the dark state. It turned out to play.

3 shows the C1 / C2 mixed orientation domain 40 at 51.3 ° C., FIG. 4 shows 51.2 ° C., and FIG. 5 shows 51.1 ° C. FIG. 3 to FIG. 5 show that the C1 / C2 mixed orientation domain 40 gradually becomes C2 at lower temperature.
An aspect in which the domain of the orientation domain 30 is grown is clarified. According to FIGS. 3 to 5, the C2 orientation 30 is:
Under cooling, the C1 alignment domain 20 shown in FIG.
It can be seen that it is formed through the C1 / C2 mixed orientation domain 40 shown in the figure.

FIGS. 7 (A) and (B) show that most domains are C1
FIG. 4 is a plan view and a cross-sectional view schematically showing an orientation domain, which is a hairpin defect and a lightning defect generated in the C1 orientation domain. FIGS. 7 (C) and 7 (D) are a plan view and a cross-sectional view schematically showing a hairpin defect and a lightning defect generated in most of the domains which are C2-oriented domains.

In FIG. 7, reference numeral 71 denotes a different structure organized by a plurality of liquid crystal molecules 72 under a plurality of chiral smectic C phases formed at intervals between the upper and lower alignment control films 14a and 14b to which the alignment treatment in the rubbing direction A is applied. 3 shows a molecular layer in an oriented state (the molecular layer 71 has a molecular layer that organizes the C1 orientation domain 73 and a molecular layer that organizes the C2 orientation domain 74).

According to FIG. 7, the molecular layer forming the C1 alignment domain 73
71 is inclined, the inclination angle theta _A near neighbor in the vertical alignment control films 14a and 14b has a sharp. In contrast, the inclination angle theta _B molecule layer 71 to form a C2 alignment domain 74 is obtuse both the upper and lower.

The pair pin defect 76 and the lightning defect 75 are generated adjacent to the C1 orientation domain 73 and the C2 orientation domain 74, and are in the bistable C1 orientation domain shown in FIGS. 7A and 7B.
In 73, a hairpin defect 76 is generated in front of the rubbing direction A, and a lightning defect 75 is generated behind.

Further, in the C2 orientation domain 74 in the bistable orientation state shown in FIGS. 7C and 7D, a lightning defect 75 is generated before and a hairpin defect 76 is generated behind according to the rubbing direction A.

In addition, when strain is applied to the cell in which the C1 alignment domain 20 shown in FIG. 2 is generated, a C2 alignment domain is generated at the applied portion (that is, the adjacent region between the C1 alignment domain and the C2 alignment domain is formed). And thus, defects and lightning defects).

FIG. 8A is an enlarged view of the liquid crystal molecules 72 and the molecular layer 71 in the alignment state under the C1 alignment, and FIG. 8B is a C-director in the alignment state under the C1 alignment (the method of forming the molecular layer 71). (Projection of molecular long axis 80 on an imaginary plane perpendicular to the line) 81.
FIG. 9 (A) shows a liquid crystal molecule in an alignment state under C2 alignment.
FIG. 9 (B) is an enlarged view of the molecular layer 72 and the molecular layer 71. FIG. 9 (B) shows the C-director in the orientation state under the C2 orientation. The molecular major axis 80 in the molecular layer 71 is arranged by changing the position along the bottom surface 83 (circle) of the cone 82 between the interface of the upper alignment control film 12a and the interface of the lower alignment control film 12b. . The left and right views of FIGS. 8 (B) and 9 (B) show the orientation state after the application of the positive (or negative) polarity pulse and the negative (or positive) polarity pulse, respectively. In FIG. 8, reference numeral 84 denotes a rotation direction of the molecular layer 71 having the bent structure with respect to the adjacent alignment control film 14a, and reference numeral 85 denotes a floating rotation of liquid crystal molecules (molecular long axis 80) adjacent to the alignment control film 14a. Direction and rotation direction 84
And 85 are in the same rotational direction. In FIG.
Reference numeral 91 denotes a rotation direction of the molecular layer 71 having the bent structure with respect to the adjacent alignment control film 14a, and reference numeral 92 denotes a floating rotation direction of liquid crystal molecules (molecular long axis 80) adjacent to the alignment control film 14a. The directions 91 and 92 are in opposite rotation directions.

FIG. 10 is parallel to the vertical alignment control films 14a and 14b,
It shows an alignment state generated when the rubbing direction A is set to the opposite direction. The alignment state shown in FIG. 10A has a liquid crystal molecule 72 under the chiral smectic C phase and a molecular layer 71 of a different alignment state organized by a plurality of liquid crystal molecules 72. In the orientation state shown in FIG. 10 (A), with reference to the rubbing direction A applied to the upper orientation control film 14a,
Molecular layer 71R in the right side in the drawing is inclined at an acute angle theta _X near its neighbor, the molecular layer 71L on the left side of the drawing is inclined at an obtuse angle theta _Y near its neighbor. When relative to the direction A of the rubbing process was applied under the orientation control layer 14b, the molecular layer 71R is inclined at an obtuse angle theta _Y near its neighbor, the molecular layer 71L is inclined at an acute angle theta _X near its neighbor I have. That is, the molecular layers 71R and 71L are
Inclination angle of the molecular layer is an acute angle theta _X and obtuse theta _Y together with the vertical. The C-director in this orientation is shown in FIGS. 10 (B) and (C). FIG. 10 (B) shows the C-director 81 of the molecular layer 71L.
These correspond to the orientation state after the application of the positive (or negative) polarity pulse and the negative (or positive) polarity pulse, respectively. FIG. 10 (C) shows the C-director 81 of the molecular layer 71R. The left and right views respectively correspond to the orientation state after the pulse application as described above.

The tilt angle of the molecular layer 71 between the C1 alignment domain 73 and the C2 alignment domain 74 shown in FIG.
Vertically with a sharp theta _A, in the case of C2 alignment domain 74, a vertical with obtuse theta _B.

The orientation state of the C-director corresponding to the C1 orientation domain 73 (shown in FIG. 8B) and the orientation state of the C-director corresponding to the C2 orientation domain 74 (shown in FIG. 9B) are shown. Are asymmetric to each other, whereas FIG. 10 (A)
The orientation states of the C-directors corresponding to the molecular layers 71R and 71L shown in FIG. 10 are optically equivalent to each other in FIGS. 10B and 10C, and are symmetric in their arrangement.

FIG. 11 is a sketch of Reference Photo 6 (magnification: 10 × 5), FIG. 12 is a sketch of Reference Photo 7 (magnification: 20 × 10), and FIG. 13 is Reference 8 (magnification). 14 is a sketch drawing of Reference Photo 9 (magnification: 20 × 10). FIG. 12 is an enlarged view of the area I shown in FIG. 11, and FIG. 13 is an enlarged view of the area II shown in FIG.
Reference photograph 6 is a photograph in which the entire surface is switched to a dark state and 90 ° crossed Nicols are set to the extinction position. The reference photographs 7 to 9 are photographs in which the 90 ° crossed Nicols are slightly shifted from the extinction position after the entire surface is switched to a dark state, and thus the entirety is blackish.

In the orientation state shown in FIG. 11, the C1 orientation domain 73 and the C2 orientation domain 74 are mixed, and a lightning defect 75 and a hairpin defect 73 are generated in adjacent areas. As can be seen from FIG. 11, when the C2 alignment domain 74 is generated by being surrounded by the C1 alignment domain 73, if the C1 alignment domain 73 changes from the C1 alignment domain 73 to the C2 alignment domain 74 along the rubbing direction A, the lightning defect 75 Occurs, and the hairpin defect 73 occurs when the orientation changes from the C2 orientation domain 74 to the C1 orientation domain 73 along the rubbing direction A.

According to the present invention, when the liquid crystal material and the alignment control film are appropriately selected as described in FIGS. Occupying 60% or more, preferably 80% or more of the entire domain excluding the above). In a preferred embodiment of the present invention, the C1 orientation domain 73
In the area around the cell (for example, near the sealing material used when sealing the cell), and
C2 alignment domains 73 can be formed.

FIG. 12 shows that the presence of bead spacers (alumina beads and silica beads having an average particle diameter of 1.5 μm) in the C1 alignment domain 73 and the C2 alignment domain 74 generated at the border of the hairpin defect 76, respectively. Hairpin defects 12
1 and lightning defect 122 (forming a coupled pair). As can be seen from FIG. 12, the hairpin defects 12 along the rubbing direction A
1 has a generation order occurring before the lightning defect 122. Conversely, in the C2 orientation domain 74, the lightning defect 122 has a generation order in which it occurs in front of the hairpin defect 121 along the rubbing direction A.

FIG. 13 shows the C1 orientation domain 73 and the C2 orientation domain 74 generated at the boundary of the lightning defect 75.
According to FIG. 13, it can be seen that the pair of hairpin defects 122 and the lightning defect 122 shown in FIG. 12 described above are generated with the same generation order.

FIG. 14 shows a C2 alignment domain 74 generated when a strain is applied to the C1 alignment domain 73. It can be seen that the hairpin defect 141 generated at this time occurs before the lightening defect 142 along the rubbing direction A.

Further, according to observations by the present inventors, it was found that hairpin defects usually occur with a width of several μm, and lightning defects occur in a zigzag shape with a line width of 1 μm or less.

Further, according to the experiment of the present inventors, as shown in FIG.
When strain was applied to the alignment domain 73, a C2 alignment domain 74 was generated in the C1 alignment domain 73, and the C2 alignment domain 74 was stably present for a long period of time. On the other hand, when strain was applied to the C2 orientation domain 74, the C1 orientation domain 73 was generated in the C2 orientation domain 74, but it was found that the C1 orientation domain 73 immediately disappeared. In this regard, the C2 orientation domain 74 is
It was found that it was present more stably than the orientation domain 73, and had a returning force to immediately return to the original orientation state even when an external impact was applied. On the other hand, it was found that the C1 orientation domain 73 had a fragile property against external impact. Further, according to Reference Photo 6, it was found that the amount of transmitted light at the extinction position of the C2 alignment domain 74 was much smaller than the amount of transmitted light at the extinction position of the C1 alignment domain 73.

According to the present invention, the lightning defect portion generates a C2 alignment domain, which occurs after a hairpin defect, in almost all regions in a cell along a direction of a uniaxial alignment process such as a rubbing process or an oblique deposition process. Can be controlled as follows. The ferroelectric smectic liquid crystal used in the present invention is not particularly limited, but according to experiments performed by the present inventors, there is a correlation between the ferroelectric smectic liquid crystal and the ferroelectric smectic liquid crystal. Used by selecting as a suitable combination with a control membrane. In particular, in a preferred embodiment of the present invention, a chiral smectic C liquid crystal having a temperature range in which a cholesteric phase and a smectic A phase are generated in a temperature decreasing process can be used.

According to an embodiment of the present invention, the temperature range in which the C1 orientation state in which the hairpin defect part occurs in front of the lightning defect part according to the direction of the rubbing treatment or the oblique vapor deposition treatment causes the lightning defect part to be in front of the hairpin defect part. The temperature range is 1/5 times or less, preferably 1/10 times or less, and particularly preferably 1/20 times or less of the temperature range in which the C2 orientation state having the generation order generated in the above occurs. Further, it is preferable that the lower limit of the temperature at which such a C1 orientation state occurs at a lower temperature is 30 ° C. or higher and 40 ° C. or higher.

FIG. 15 schematically illustrates an example of a cell for explaining the operation of the ferroelectric liquid crystal. 151A and 151B are In ₂ O ₂ , Sn
A substrate (glass plate) covered with a transparent electrode made of a thin film of O ₂ or ITO, between which an SmC ^* (chiral smectic C) phase in which the liquid crystal molecule layer 152 is oriented perpendicular to the glass surface or SmH ^* (Chiral smectic H)
Phase liquid crystals are enclosed. A bold line 153 represents a liquid crystal molecule, which has a dipole moment (P 双) 154 in a direction perpendicular to the molecule. When a voltage higher than a certain threshold is applied between the electrodes on the substrates 151A and 151B, the helical structure of the liquid crystal molecules 153 is unwound, and the liquid crystal molecules 153 are oriented so that all dipole moments (P⊥) 154 are directed to the electric field. Can be changed. The liquid crystal molecules 153 have an elongated shape and exhibit refractive index anisotropy in the major axis direction and the minor axis direction. Therefore, for example, if crossed Nicol polarizers are placed above and below the glass surface, the voltage application polarity It is easily understood that the liquid crystal optical modulation element changes its optical characteristics depending on the characteristics.

The surface stable ferroelectric liquid crystal cell in a bistable alignment state used in the liquid crystal element of the present invention can have a sufficiently small thickness (for example, 0.1 μm to 3 μm). As shown in FIG. 16, as the liquid crystal layer becomes thinner, the helical structure of the liquid crystal molecules is unwound and becomes a non-helical structure even when no electric field is applied, and the dipole moment P or P ′ thereof is upward ( 164A) or downward (164B). When an electric field Ea or Eb having a different polarity equal to or more than a certain threshold is applied to such a cell by the voltage applying means 161A and 161B as shown in FIG. 16, the dipole moment becomes
The liquid crystal molecules change their directions to upward 164A or downward 164B in accordance with the electric field vector of the electric field Ea or Eb, and the liquid crystal molecules are aligned in one of the first stable state 163A and the second stable state 163B accordingly.

The effects obtained by the ferroelectric liquid crystal cell are, first, that the response speed is extremely fast, and second, that the alignment of the liquid crystal molecules has bistability. The second point will be further described with reference to FIG. 16, for example. When an electric field Ea is applied, the liquid crystal molecules are oriented to the first stable state 163A.
This state is stable even when the electric field is turned off. Also, when an electric field Eb in the opposite direction is applied, the liquid crystal molecules are oriented to the second stable state 163b and change the direction of the molecules, but remain in this state even after the electric field is turned off. As long as the applied electric field Ea does not exceed a certain threshold value, the respective alignment states are also maintained.

 Hereinafter, the present invention will be described with reference to examples.

Example 1 Two 1.1 mm thick glass plates provided with a 1000 mm thick ITO film were prepared, and alicyclic polyimide film forming solution "Sun Ever 15" manufactured by Nissan Chemical Industries, Ltd. was formed on each glass plate.
A 0% (trade name) N-methylpyrrolidone / n-butyl cellosolve = 3/1 (weight ratio) 3% solution was applied by a spinner having a rotation speed of 3000 rpm for 30 seconds. After the film formation, a heating and baking treatment was performed at 250 ° C. for about 1 hour. At this time, the film thickness was 500 °.
This coating film was subjected to a one-way rubbing treatment with an acetate touch cloth. Thereafter, the glass plate was washed with isopropyl alcohol, and dried at 120 ° C. for 20 minutes. Thereafter, alumina beads having an average particle size of about 1.5 μm were sprayed on one of the glass plates, and then the rubbing treatment axes were parallel to each other and the treatment directions were the same.
A cell was created by stacking two glass plates.

"CS-1014" (trade name), which is a ferroelectric smectic liquid crystal manufactured by Chisso Corporation, was vacuum-injected into this cell under the isotropic phase, and then was injected at 0.5 ° C / h from the isotropic phase at 30 ° C. It was possible to orient it by slowly cooling it.

The phase change in the cell of this embodiment using “CS-1014” is
It was as follows.

This cell had a stable C2 orientation domain at a temperature of about 50 ° C. to −20 ° C., and had a very good monodomain property.

 Subsequent experiments were performed at a temperature of 25 ° C.

After sandwiching the above liquid crystal cell between a pair of 90 ° crossed Nicol polarizers, and applying a 30 μV pulse of 50 μsec,
Set the 90 ° crossed Nicols to the extinction position (darkest state), measure the transmittance at this time with a photomultiplier, and then apply a -30 V pulse of 50 μsec, and check the transmittance (bright state) at this time. When measured by the same method, the transmittance in the darkest state was 1.0%, and the transmittance in the bright state was 8.0%. Therefore, the contrast was 8.

Further, the above liquid crystal cell was subjected to an impact durability test using a drop durability tester “DT-50” (trade name) manufactured by Yoshida Seiki Co., Ltd. At this time, the drop impact 20G (G: gravitational acceleration 9.8m / sec ² ) to 10G
When the liquid crystal cell of the present example was tested by increasing it at a time, a disturbance of the alignment did not occur even when a drop impact of 80 G was given, and when the same driving pulse as described above was applied to this liquid crystal cell, the same It showed switching characteristics.

Examples 2 to 6 Cells were obtained in the same manner as in Example 1 except that the alignment control films and the liquid crystal materials shown in Table 1 were used.

Table 2 shows the results of the contrast ratio and durability of the same test as in Example 1 for each.

Next, when the phase transition temperature of the cell of this example was measured,
The results are shown in Table 3 below.

According to Table 3, the Sm ^* C1 / C2 phase transition point and Sm ^* C1 / C2-
It can be seen that the Sm ^* C2 phase transition point shows a value unique to the cell and appears differently for each cell.

Next, after applying a 30 μV pulse of 50 μsec to the cells of Examples 1 to 6, the 90 ° crossed Nicols were set at the extinction position.
After applying the -30 V pulse of c, the 90 ° crossed Nicols were again set to the extinction position, and it was again confirmed that all of them were in a black state (measuring temperature 25 ° C.).

Comparative Examples 1 to 5 A cell using the alignment control film and the liquid crystal material shown in Table 4 was prepared in exactly the same manner as in Example 1.

Contrast ratio and durability results were obtained for each cell. Table 5 shows the results.

Next, when the phase transition temperature of this comparative example cell was measured,
The results are shown in Table 6 below.

As can be seen from Table 6, none of the cells of the comparative example had a temperature range in which Sm ^* C2 was generated.

Next, after applying a 30 μV pulse of 50 μsec to the cells of Comparative Examples 1 to 5, the 90 ° crossed Nicols were set to the extinction position.
After applying the -30 V pulse of c, the 90 ° crossed Nicols were again set to the extinction position, and it was confirmed that all of them were in a blue state (measuring temperature 25 ° C.). In this respect, it was found that the two states were different from the two states of the extinction positions in Examples 1 to 6, and the orientation states were also different.

Comparative Example 6 A liquid crystal cell was prepared in the same manner as in Example 1 except that the rubbing treatment was performed in parallel with the upper and lower glass substrates and in the opposite directions, and the same measurement as in Example 1 was performed. The results shown in Table 7 below were obtained.

Next, after applying a 30 μV pulse of 50 μsec to this comparative example cell, the 90 ° crossed Nicols were set to the extinction position.
After a black state was generated and subsequently a -30 V pulse of 50 μsec was applied, the 90 ° crossed Nicols were again set to the extinction position, and it was confirmed that the state was blue (measurement temperature 25
° C). In this respect, it was found that the two states of the extinction positions in Examples 1 to 6 were different, and that the orientation states were also different.

According to the results of the impact tests performed in Comparative Examples 1 to 6, most of the generated orientation disorder was in the form of a sanded texture, and switching was not caused by the application of the 30 V and −30 V pulses of 50 μsec.

〔The invention's effect〕

As can be seen from the above Examples and Comparative Examples, the present invention can provide improved shock resistance as compared with the conventional ferroelectric liquid crystal pulse and provide a display screen with improved contrast. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view of the liquid crystal element of the present invention. Fig. 2 ~
FIG. 6 is a sketch drawing of a micrograph showing the temperature dependence of the ferroelectric liquid crystal alignment state. FIG. 7A is a plan view schematically showing a C1 orientation domain and a C2 orientation domain, and FIG. 7B is a sectional view thereof. FIG. 7 (C) is a plan view schematically showing another C1 orientation domain and another C2 orientation domain, and FIG. 7 (D) is a sectional view thereof. Fig. 8 (A)
Is a schematic diagram of the C1 orientation, and FIG. 8 (B) is a projection showing the C-director. FIG. 9 (A) is a schematic view of the C2 orientation, and FIG. 9 (B) is a projection showing the C-director. FIG. 10 (A) is a schematic view showing a conventional orientation state, and FIGS. 10 (B) and (C) are projection views showing the C-director. FIG. 11 to FIG. 14 are sketch diagrams of micrographs showing a C1 orientation domain and a C2 orientation domain. FIG. 15 is a perspective view schematically showing the operation of the ferroelectric liquid crystal element. FIG. 16 is a perspective view schematically showing the operation of the surface stable ferroelectric liquid crystal element in a bistable alignment state used in the present invention.

Claims (23)

(57) [Claims] A) a pair of substrates subjected to a uniaxial orientation treatment; b. A chiral smectic C disposed between the pair of substrates.
A chiral smectic liquid crystal having a bistable alignment state different between a high temperature side and a low temperature side in a phase, wherein the chiral smectic liquid crystal has an alignment state at a low temperature side, and c. Optically identifying the bistable alignment state A chiral smectic liquid crystal device comprising: 2. The liquid crystal device according to claim 1, wherein the alignment state on the low-temperature side is an alignment state developed at a temperature of 30 ° C. or more at a reduced temperature. 3. The liquid crystal device according to claim 1, wherein the alignment state on the low temperature side is an alignment state developed at a temperature of 40.degree. 4. A pair of substrates having been subjected to a uniaxial alignment treatment, b. A chiral smectic liquid crystal capable of generating two different states of a tendency to generate a pair of coupled hairpin defects and lightening defects, A chiral smectic liquid crystal having an orientation state showing a generation order in which a lightning defect occurs before and a hairpin defect occurs behind in the direction of the uniaxial orientation treatment; andc. Means for optically distinguishing the two different states, A chiral smectic liquid crystal device having 5. The chiral smectic liquid crystal device according to claim 4, wherein the domain occupied by the domain in the alignment state showing the generation order has a size that can ignore the domain in the alignment state showing the other generation order. 6. The domain of the orientation state showing the generation order has an occupied area generated by growing the domain of the orientation state showing the other generation order to a negligible size at a reduced temperature. The chiral smectic liquid crystal device according to the above. 7. The temperature range in which the domain of the orientation state showing the other generation order produces an occupied area of a size that cannot be ignored under the temperature-lowering condition, 7. The chiral smectic liquid crystal device according to claim 6, wherein the temperature range is 1/5 or less. 8. A temperature range in which the domain of the orientation state showing the other generation order produces an occupied area of a size that cannot be ignored under the temperature-lowering condition, 7. The chiral smectic liquid crystal device according to claim 6, wherein the temperature range is 1/10 or less of the temperature range. 9. The temperature range in which the domain of the orientation state showing the other generation order produces an occupied area of a size that cannot be ignored under the temperature decrease is set to a temperature range in which the occupied area of the domain having a size that can be ignored is ignored. 7. The chiral smectic liquid crystal device according to claim 6, wherein the temperature range is 1/20 or less. 10. The chiral smectic liquid crystal device according to claim 6, wherein a lower limit temperature at which the domain of the orientation state exhibiting the other generation order produces an occupied area of a size that cannot be ignored under the temperature decrease is 30 ° C. or more. 11. The chiral smectic liquid crystal device according to claim 6, wherein the lower limit temperature at which the domain of the alignment state exhibiting another generation order produces an occupied area of a size that cannot be ignored under the temperature decrease is 40 ° C. or more. 12. The pair of substrates are arranged to face each other with a sealing material interposed therebetween, and the other domain of the orientation state showing the generation order is generated in the vicinity of the sealing material, and the alignment state showing the generation order is provided. 6. The chiral smectic liquid crystal device according to claim 5, wherein the domain of (a) is formed inside a region near the sealing material. 13. The chiral smectic liquid crystal device according to claim 4, wherein the two states in the extinction position of the domain in the alignment state indicating the generation order are optically equivalent. 14. The chiral smectic liquid crystal element according to claim 4, wherein said uniaxial alignment treatment is applied to an alignment control film provided on a substrate. 15. The chiral smectic liquid crystal device according to claim 14, wherein said alignment control film is made of polyimide, polyamide or polyester. 16. The chiral smectic liquid crystal device according to claim 14, wherein said alignment control film is made of polyimide. 17. The chiral smectic liquid crystal device according to claim 14, wherein the alignment control film is a film provided on an insulating film formed on a substrate. 18. The chiral smectic liquid crystal device according to claim 4, wherein said uniaxial alignment treatment is rubbing. 19. A pair of substrates provided with a uniaxial alignment treatment, b. A layer structure formed by a plurality of layers organized by a plurality of liquid crystal molecules, and the formation of a unique helical arrangement structure is suppressed. A chiral smectic liquid crystal having an aligned structure, wherein the layer structure has a bent structure that can cause a lightning defect and a hairpin defect, and a lightning defect in front and a hairpin defect in back along the direction of the uniaxial alignment treatment. Temperature range in which the layer structure of the region surrounded by the front lightning defect and the rear hairpin defect becomes a main region,
And hairpin defects in front, along the direction of uniaxial orientation processing,
A chiral smectic liquid crystal device having a chiral smectic liquid crystal, in which a lightning defect occurs behind, and a temperature range in which a layer structure of a region surrounded by the hairpin defect before and the lightening defect behind becomes a main region. 20. A method of manufacturing a liquid crystal device having a step of disposing a chiral smectic liquid crystal between a pair of substrates to which a uniaxial alignment treatment has been applied, the method comprising the steps of:
A hairpin defect occurs behind, and the temperature range in which the layer structure of the region surrounded by the previous lightning defect and the rear hairpin defect becomes a main region is passed by cooling, and further along the direction of the uniaxial orientation process by cooling. Hairpin defects in front,
A method for producing a liquid crystal element, comprising: a step of generating a lightning defect at the rear and a temperature range in which a layer structure of a region surrounded by the hairpin defect at the front and the lightning defect at the rear becomes a main region. 21. A bent structure having a layer structure formed by a pair of substrates and a plurality of layers organized by a plurality of liquid crystal molecules, having an arrangement structure in which formation of a unique helical arrangement structure is suppressed. A chiral smectic liquid crystal element having a chiral smectic liquid crystal whose main direction is a region in which a rotation direction with respect to an adjacent substrate is in a direction opposite to a floating rotation direction of liquid crystal molecules adjacent to the adjacent substrate. 22. The chiral smectic liquid crystal has a temperature range in which a smectic A phase is generated on a higher temperature side than a temperature range of the chiral smectic phase, and is cooled to a chiral smectic C phase via the temperature range in which the smectic A phase is generated. 22. The chiral smectic liquid crystal device according to claim 21, comprising: 23. The chiral smectic liquid crystal has a temperature range in which a cholesteric phase and a temperature range in which a smectic A phase is generated on a higher temperature side than a temperature range of the chiral smectic phase, and a temperature range in which the cholesteric phase is generated and a smectic A phase. 22. The chiral smectic liquid crystal device according to claim 21, wherein the device is cooled to a chiral smectic phase via a temperature range in which is generated.