JPH01158415A - Ferroelectric smetic liquid crystal element - Google Patents

Abstract

PURPOSE:To obtain high stability to a shock or strain by employing a rubbing treatment and a slanting vapor-deposition treatment as an orientation treatment and obtaining a bistable orientation state which has an array state of good order. CONSTITUTION:Orientation-treated films 14a and 14b which are rubbed (as shown by arrow) in parallel and in the same direction are arranged. Ferroelectric smetic liquid crystal 15 is arranged between substrates 11a and 11b, the distance of the gap between substrates 11a and 11b is set small enough to suppress the formation of the spiral array structure of the ferroelectric smetic liquid crystal 15, and the ferroelectric smetic liquid crystal 15 is put in the bistable orientation state. Then, the sufficiently small distance is held by beads spacers 16. Therefore, the bistable orientation state is different between the high temperature side and low temperature side of the temperature range of a chiral smetic C phase. Consequently, the high stability against a shock and strain is obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to liquid crystal elements used in liquid crystal displays, liquid crystal light shunters, etc., particularly liquid crystal elements using ferroelectric liquid crystal, and more specifically relates to liquid crystal elements using ferroelectric liquid crystal. The present invention relates to a liquid crystal element which has significantly improved properties, improved durability of the element, and improved contrast between a dark state and a bright state.

[Background technology]

A type of display element that utilizes the refractive index anisotropy of ferroelectric liquid crystal molecules to control transmitted light in combination with a polarizing element has been proposed by N., A., and Clark et al.
6-107216, US Pat. No. 4,367,924, etc.). This ferroelectric liquid crystal generally has a chiral smectic C phase (SmC*) or H phase (S m H) in a specific temperature range, and the chiral smectic C or H phase that produces a helical alignment structure in the bulk state. In a bistable alignment state obtained by placing a liquid crystal under temperature at a spacing between a pair of substrates set at a distance sufficiently small to suppress the formation of a helical alignment structure, the first It has a memory property of taking either an optically stable state or a second optically stable state and maintaining that state when no electric field is applied, and also has a fast response property to changes in the electric field. , and is expected to be widely used as high-speed and memory-type display elements.

In order for an optical modulation device using a ferroelectric smectic liquid crystal that has produced this bistable orientation state to exhibit the aforementioned memory characteristics and high-speed response characteristics as a product, the bistable orientation state must be stable and uniform. It was necessary for the element to exist, to have excellent durability as an element, and to have a large contrast ratio between the bright state and the dark state.

In US Pat. No. 4,639,089, Kaida et al. applied a ferroelectric smectic liquid crystal having a temperature range that produces a cholesteric phase to a liquid crystal element having a uniaxial alignment treatment axis imparted by rubbing treatment or oblique evaporation treatment. It has been revealed that a ferroelectric smectic liquid crystal device with a bistable alignment state has been realized.

A ferroelectric smectic liquid crystal element with a uniform bistable alignment state achieved by rubbing treatment and oblique evaporation treatment is
, A. Compared to the one by Clark et al., the amount of transmitted light under the bright state memory was small (sometimes).

The above-mentioned ferroelectric smectic liquid crystal element in a bistable alignment state has a uniform alignment state, so that the liquid crystal molecules are arranged with a high degree of order. This highly ordered state of the liquid crystal molecules has a property of being brittle against stress from outside the cell, such as impact force or strain force, and when such force is applied, the state of arrangement of the liquid crystal molecules is disturbed. This typically results in sanded texture.

The occurrence of sanded texture due to impact force has been clarified, for example, in USP 4,674,839 by Tsuboyama et al.

By adopting a rubbing treatment method or an oblique evaporation treatment method as an orientation treatment method, the present inventors achieved a bistable orientation state with a high degree of order, and were able to resist stress from outside the cell. We have discovered an orientation state that exhibits strong stability against

[Summary of the invention]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a ferroelectric smectic liquid crystal element in a uniform bistable alignment state that exhibits strong stability against impact or strain.

Another object of the present invention is to provide a ferroelectric smectic liquid crystal device having a uniform bistable alignment state with a high contrast between the bright state and the dark state.

The present invention provides: a) a pair of substrates provided with a uniaxial alignment treatment axis; b) a bistable orientation disposed between the pair of substrates, which differs between the high temperature side and the low temperature side within the ferroelectric smectic phase; a ferroelectric smectic liquid crystal that generates a state and has an orientation state on the low temperature side; c. a ferroelectric smectic liquid crystal that has means for optically identifying the bistable orientation state; The device has a first feature, and a second feature is a: a pair of substrates provided with uniaxially oriented axes, the uniaxially oriented axes being parallel or substantially parallel to each other (crossing angle of 30° or less); ) and whose axes are in the same direction; b. a pair of bonded ferroelectric smectic liquid crystals in a bistable alignment state that tends to generate hairpin defects and lightning defects, the uniaxial a ferroelectric smectic liquid crystal having an orientation state exhibiting a developmental order that generates lightning defects at the front and hairpin defects at the rear according to the direction of the alignment treatment axis, and c. means for optically identifying the bistable state. The ferroelectric smectic liquid crystal element has a second feature.

[Detailed description of aspects of the invention]

FIG. 1 shows an example of the ferroelectric liquid crystal cell of the present invention, which is a substrate (glass plate) covered with transparent electrodes 12a and 12b such as %Tin Oxide. Thickly deposited edge films 13a and 13b (Si02 film,
Ti02 film, Ta205 film, etc.) and 50 to 1000 deposited orientation control films 14a and 14b made of polyimide, polyamide, polyester, etc. are laminated, respectively.

At this time, rubbing treatment (in the direction of the arrow) so that the alignment treatment films 14 are parallel and in the same direction (direction A in FIG. 1)
a and 14b are arranged. A ferroelectric smectic liquid crystal 15 is arranged between the substrates 11a and llb, and the distance between the substrates 11a and llb is sufficient to suppress the formation of a helical alignment structure of the ferroelectric smectic liquid crystal 15. The distance is set to be small (for example, 0.1 μm to 3 μm), and the ferroelectric smectic liquid crystal 15 is in a bistable alignment state.

The sufficiently small distance described above is maintained by bead spacers 16 (silica beads, alumina beads) placed between the substrates 11a and llb.

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

According to experiments by the present inventors, by using the liquid crystal material and alignment control film clarified in the above-mentioned examples, a bistable alignment state that occurs on the high temperature side and low temperature side in the temperature range of the chiral smectic C phase The fact that the bistable orientation state on the low temperature side exhibits strong stability against impact or strain, and that it exhibits a large contrast between the bright and dark states leads to the orientation state that produces the developmental order that stings insects. On the other hand, on the high-temperature side, it has an orientation state that causes a generation order in which hairpin defects occur at the front and lightening defects occur at the rear according to the rubbing treatment direction. Hereinafter, in the temperature range of the chiral smectic C phase, for convenience, the above-mentioned orientation state on the high temperature side will be referred to as "l'-c orientation", and the orientation state on the low temperature side will be referred to as "rC2 orientation".

The expression "for convenience" is used here because, as will be described later, the two different orientation states do not depend only on temperature.

Figure 2 is a sketch of reference photo 1 (magnification: loXIO), Figure 3 is a sketch of reference photo 2 (magnification +10X10), and Figure 4 is a sketch of reference photo 3 (magnification = 10XIO).
Figure 5 is a sketch of reference photo 4 (magnification: 10).
FIG. 6 is a sketch diagram of reference photograph 5 (magnification: 10×10 times).

Figure 2 shows the state of C orientation, Figure 6 shows the state of C2 orientation, and Figures 3 to 5 show the generation order in which lightning defects occur at the front and hairpin defects at the rear according to the rubbing direction. A mixed state (hereinafter referred to as “c
1/C2 mixed orientation). 2 to 6 are all at the extinction position (the darkest position under 90° crossed Nicols).

Furthermore, according to the observations of the present inventors, the area c, shown in FIGS. 2 to 5, occupied by the alignment domain 20 was predominantly large.

The liquid crystal material used at this time was rcs-1014J (trade name), a ferroelectric smectic liquid crystal manufactured by Chisso Corporation, and the alignment control film was an alicyclic polyimide film forming liquid manufactured by Yasan Kagaku Kogyo Co., Ltd. "Sunever 150" (trade name) was used. The rubbing treatment was performed so that the upper and lower substrates were parallel to each other and in the same treatment direction, and the interval between the upper and lower substrates was set to 1.5 μm (details are shown in Example 1 above). The phase transition temperature in this cell was as follows.

ISO; Togoyoshi phase Ch; cholesteric phase SmA; smectic A phase Sm*c,; c of chiral smectic C phase, oriented phase Sm*c, /C2; c of chiral smectic C phase
, /C2 mixed orientation phase Sm*C2; phase Cry in C2 orientation state among chiral smectic C phase; crystal phase l5o-Ch phase transition point, Ch-8mA phase transition point, SmA
-3m*c, phase transition point and Sm*C2-Cry, phase transition point is the temperature measured by "r F P 800 temperature control device" (trade name) manufactured by Mettler, Switzerland, Sm*CI
Sm*c,/C2 phase transition point and Sm*c,/C2-
The 8m*C2 phase transition point is the temperature determined by microscopic observation under decreasing temperature.

According to FIG. 2, c, the extinction position of the alignment domain 20 (the 90° crossed Nicol position that sets the dark state to the darkest) is a blue state, a blue bright state 21 and a blue dark state. There are 22. According to FIG. 6, the extinction position of the C2 orientation domain 30 is a black state, and there exists a white bright state 31 and a black dark state 32. Moreover, according to FIGS. 3 to 5, it is clear that the C alignment domain 20 whose extinction position is blue and the C2 alignment domain 30 whose extinction position is black coexist.

Also, c, orientation domain 20. After applying a pulse of +30V for 50 μsec under each condition of the C2 orientation domain 30 and the c and /C2 mixed orientation domain 40, the state at the extinction position was observed, and it was found that the extinction position of the c orientation domain 20 was blue. The extinction position of the C2-oriented domain 30 was black. Furthermore, c, orientation domain 20.
Under each condition of the C2 orientation domain 30 and c, /C2 mixed orientation domain 40, 50 μsec, -30
After applying a V inversion pulse, the state at the extinction position was observed, and as expected, the extinction position of the c-aligned domain 20 was blue, and the extinction position of the C2-oriented domain 30 was black.

From the above experiments, it was found that in the temperature range of the chiral smectic C phase, the C phase has different orientation states, 20 orientation domains and 30 C2 orientation domains, and as the temperature decreases, C2
It was found that the C2 orientation domain 30 gradually grows and becomes so large that the C2 orientation domain 20 can be ignored (the area occupied by the C2 orientation domain 30 is 60% or more of all domains excluding the area around the sealant). have). or,
As will be made clear in the examples below, the C2-oriented domain 30
The ferroelectric smectic liquid crystal element in the bistable alignment state that accounts for most of It has been found that compared to the orientation state (orientated state produced by), it exhibits stronger stability against external impact forces and strain forces, and a greater contrast between the bright and dark states.

Figure 3 is 51.3℃, Figure 4 is 51.2℃, Figure 5 is 51.3℃.
A c,/C2 mixed orientation domain 40 at 1.1'C is shown. FIGS. 3 to 5 clearly show how the c,/C2 mixed orientation domain 40 gradually grows into the C2 orientation domain 30 as the temperature decreases.

According to FIGS. 3 to 5, the C2 orientation 30 is formed through the c, orientation domain 20 shown in FIG. 2 and the c, /C2 mixed orientation domain 40 shown in FIGS. It can be seen that

In Figures 7(A) and (B), most domains are c,
FIG. 3 is a plan view and a cross-sectional view schematically showing a hairpin defect and a lightning defect generated in the orientation domain. In FIGS. 7(C) and (D), most of the domains are C2-oriented domains, and this C2
FIG. 2 is a plan view and a cross-sectional view schematically showing a hairpin defect and a lightning defect generated in an alignment domain.

71 in FIG. 7 indicates different alignments organized by liquid crystal molecules 72 under a plurality of chiral smectic C phases formed in the interval between the upper and lower alignment control films 14a and 14b that have been subjected to alignment treatment in the rubbing direction A. A molecular layer of the state (as the molecular layer 71, c, a molecular layer organizing the orientation domain 73, and C2
and a molecular layer organizing the orientation domains 74).

According to FIG. 7, c, the molecular layer 71 forming the alignment domain 73 is inclined, and the upper and lower alignment control films 14a and 14b
The inclination angle θ near the adjacent part is an acute angle. On the other hand, the inclination angle θ8 of the molecular layer 71 forming the C2-oriented domain 74 is an obtuse angle both above and below.

The bare pin defect 76 and the lightning defect 75 occur adjacent to the c-oriented domain 73 and the C2-oriented domain 74, and the c-oriented domain 73 is in the bistable orientation state shown in FIGS. 7(A) and (B). Inside, according to the rubbing direction A, there is a hairpin defect 76 at the front and a lightning defect 7 at the back.
5 is occurring.

Furthermore, within the C2 orientation domain 74 in the bistable orientation state shown in FIGS. 7(C) and (D), according to the rubbing direction A, there is a lightning defect 75 at the front and a hairpin defect 7 at the rear.
6 is occurring.

Furthermore, when a strain is applied to a cell in which the c orientation domain 20 shown in FIG.
resulting in adjacent regions with bi-oriented domains, thus generating defects and lightning defects).

FIG. 8(A) is an enlarged view of the liquid crystal molecules 72 and the molecular layer 71 in the alignment state under c, orientation, and FIG. 8(B) is an enlarged view of the C-director (molecular layer 71 81 of the molecular long sleeve 80 onto an imaginary plane perpendicular to the normal line of . FIG. 9(A) is an enlarged view of the liquid crystal molecules 72 and the molecular layer 71 in the alignment state under C2 orientation.
B) represents the C-director in the orientation state under C2 orientation. The long axes 80 of the molecules in the molecular layer 71 are arranged at different positions along the bottom surface 83 (circular) of the cone 82 between the interface of the upper alignment control film 12a and the interface of the lower alignment control film 12b. .

Note that the left and right figures in FIGS. 8(B) and 9(B) are the orientation states after the application of a positive (or negative) polarity pulse and a negative (or positive) polarity pulse, respectively.

FIG. 1θ is parallel to the upper and lower alignment control films 14a and 14b, but represents the alignment state that occurs when the rubbing direction A is opposite to each other. The alignment state shown in FIG. 10(A) is the liquid crystal molecule 7 under the chiral smectic C phase.
2 and a plurality of liquid crystal molecules 72 in different orientation states. In the alignment state shown in FIG. 1O (A), the molecular layer 71R on the right side of the figure is inclined at an acute angle θX near its adjacent area, with reference to the direction A of the rubbing treatment applied to the upper alignment control film 14a. The left molecular layer 71L is inclined at an obtuse angle θY near its adjacent portion. Lower orientation control film 1
4b, the molecular layer 71R is inclined at an obtuse angle θY in the vicinity thereof, and the molecular layer 71L is inclined at an acute angle θX in the vicinity thereof.

That is, in both the upper and lower molecular layers 71R and 71L, the inclination angles of the molecular layers are an acute angle θX and an obtuse angle θY. The C-director in this oriented state is shown in FIGS. 10(B) and 10(C). FIG. 1θ (B) shows the C-director 81 of the molecular layer 71L, and the left and right diagrams are respectively positive (
(or negative) polarity pulse and the alignment state after application of the negative (or positive) polarity pulse. Further, FIG. 1θ (C) shows the C-director 81 of the molecular layer 71R, and the left and right diagrams respectively correspond to the orientation state after the same pulse application as described above.

The inclination angle of the molecular layer 71 between the C2 orientation domain 73 and the C2 orientation domain 74 shown in FIG. In this case, both the upper and lower sides are obtuse angles θ8.

In addition, c, the orientation state of the C-director corresponding to the orientation domain 73 (shown in FIG. 8(B)) and the C2 orientation domain 7
The orientation state of the C-director corresponding to 4 (Fig. 9(B)
) are asymmetrical to each other, whereas the orientation states of the C-directors corresponding to the molecular layers 71R and 71L shown in FIG. 10(A) are as shown in FIG. 10(B) and (
C) are optically equivalent to each other and are symmetrical in their arrangement.

Figure 11 is a sketch of reference photo 6 (magnification: 10x5x), Figure 12 is a sketch of reference photo 7 (magnification: 20x10x), and Figure 13 is a sketch of reference photo 8 (magnification: 20x).
FIG. 14 is a sketch diagram of reference photograph 9 (magnification: 20X10 times). Figure 12 shows
FIG. 13 is an enlarged view of area (2) shown in FIG. 11, and FIG. 13 is an enlarged view of area (2) shown in FIG. Reference photo 6 is a photo when the entire surface is switched to a dark state and 900 crossed Nicols is set at the extinction position.

Reference photos 7 to 9 are all photos taken when the 90° crossed nicols were slightly shifted from the extinction position after the entire surface was switched to a dark state, so the entire image is blackish.

In the alignment state shown in FIG. 11, c-alignment domains 73 and C2-alignment domains 74 coexist, and lightning defects 75 and hairpin defects 73 occur in adjacent regions of each domain. As can be seen from FIG. 11, when the C2 orientation domain 74 is generated surrounded by the C orientation domain 73, the C2 orientation domain 73 changes to the C2 orientation domain 74 along the rubbing direction A. Lightning defect 75 is generated, and further rubbing processing direction A
along C2 orientation domain 74 to c, orientation domain 7
3, a hairpin defect 73 occurs.

As clarified in the above-mentioned FIGS. 2 to 6, the present invention has the following features:
If the liquid crystal material and alignment control film are appropriately selected, C.
The bi-oriented domain 74 can be generated over most of the area within the cell (occupying an area of 60% or more, preferably 80% or more of the entire domain excluding the peripheral area of the sealant). In a preferred embodiment of the present invention, c. the orientation domain 73 is formed in the cell periphery (for example, near a sealing material used to seal the cell), and the C2 orientation domain 73 is formed inside the cell periphery; Can be done.

FIG. 12 shows that the cause is the presence of bead spacers (alumina beads or silica beads with an average particle size of 1.5 μm) in the C, orientation domain 73 and C2 orientation domain 74, which are generated at the border of the hairpin defect 76. The resulting hairpin defect 121 and lightning defect 122 (forming a combined pair) are clarified. As can be seen from FIG. 12, within the cl orientation domain 73, the hairpin defect 121 is aligned with the lightning defect 12 along the rubbing direction A.
It has a developmental order that occurs in front of 2. Conversely, within the C2 orientation domain 74, there is an order in which the lightning defects 122 occur in front of the hairpin defects 121 along the rubbing direction A.

FIG. 13 shows the c caused by the lightning defect 75.
, revealing an orientation domain 73 and a C2 orientation domain 74. According to FIG. 13, a pair of combined hairpin defects 122 and lightning defects 1 shown in FIG.
It can be seen that 22 occurs with a similar order of occurrence.

FIG. 14 shows a C2 orientation domain 74 generated when strain is applied to the c orientation domain 73. It can be seen that the hairpin defect 141 generated at this time occurs in front of the lightning defect 142 along the rubbing direction A.

Further, according to the observations of the present inventors, it has been 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.

Also, according to the experiments conducted by the present inventors, as shown in FIG.
When strain was applied to the oriented domain 73, a C2 oriented domain 74 was generated within the oriented domain 73, and this C2 oriented domain 74 existed stably for a long period of time. On the other hand, when strain was applied to the C2 orientation domain 74, a c orientation domain 73 was generated within the C2 orientation domain 74;
was found to disappear immediately. From this point of view, the C2 orientation domain 74 exists more stably than the C2 orientation domain 73, and also has the ability to return to its original orientation immediately even if it receives an external impact. It turns out. On the other hand, it was found that the c-alignment domain 73 has a property of being brittle against external impact. Further, according to reference photograph 6, it was found that the amount of transmitted light at the extinction position of the C2 orientation domain 74 was a much smaller value than the amount of transmitted light at the extinction position of the C2 orientation domain 73.

In the present invention, the lightning defect portion generates a C2-oriented domain in most regions within the cell, which occurs behind the hairpin defect, along the direction of uniaxial alignment treatment such as rubbing treatment or oblique evaporation treatment. can be controlled in various ways. The ferroelectric smectic liquid crystal used in the present invention is not particularly limited, but according to experiments by the present inventors, there is a correlation between the ferroelectric smectic liquid crystal and the alignment control film. Suitable combination with control membrane and
- It is used by selecting. Particularly, 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 the temperature cooling process can be used.

In the specific example of the present invention, according to the direction of the rubbing treatment or the oblique evaporation treatment, the paired bin defects occur in front of the lightning defects. 11 of the temperature range that produces a C2 orientation state with developmental order that occurs before
It is preferably 5 times or less, preferably 1710 times or less, particularly 1/20 times or less. Further, it is preferable that the lower limit of the temperature at which such an oriented state occurs as the temperature decreases is 30° C. or higher and 40° C. or higher.

FIG. 15 schematically depicts an example of a cell for explaining the operation of a ferroelectric liquid crystal. 151A and 151B are substrates (glass plates) covered with transparent electrodes made of thin films such as In2O2, 5n02, or ITO, and between them, a liquid crystal molecular layer 152 is oriented perpendicularly to the glass surface using SmC* (chiral smectic). C) phase or Smm Kimoto chiral smectic H) phase liquid crystal is enclosed. A thick line 153 represents a liquid crystal molecule, and this liquid crystal molecule 153 has a dipole moment (P) 154 in a direction perpendicular to the molecule. When a voltage equal to or 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 unraveled, and the liquid crystal molecules 153 are aligned in the direction such that all the dipole moments (P soil) 154 are oriented in the direction of the electric field. can be changed. The liquid crystal molecules 153 have an elongated shape and exhibit refractive index anisotropy in the major and minor axis directions. Therefore, for example, if crossed Nicol polarizers are placed above and below the glass surface, the polarity of voltage application can be changed. It is easily understood that a liquid crystal optical modulation element whose optical characteristics change according to

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 thin thickness (for example, 0.1 μm to 3 μm). As shown in Figure 16, even when no electric field is applied, the helical structure of the liquid crystal molecules unwinds and becomes a non-helical structure, and its dipole moment P or P' is upward (164A) or downward (164B)
). In such a cell, the 16th
As shown in the figure, when an electric field Ea or Eb of different polarity above a certain threshold value is applied by the voltage applying means 161A and 161B, the dipole moment is directed upward 164A or downward 164B in accordance with the electric field vector of the electric field Ea or Eb. The liquid crystal molecules are oriented in either the first stable state 163A or the second stable state 163B accordingly.

The first effect obtained by this ferroelectric liquid crystal cell is that the response speed is extremely fast, and the second effect is that the alignment of liquid crystal molecules has bistability.

To further explain the second point, for example, with reference to FIG.
When the electric field Ea is applied, the liquid crystal molecules enter the first stable state 163
A, and this state is stable even when the electric field is turned off. Also, when applying an electric field Eb in the opposite direction, the liquid crystal molecules
The molecules are oriented to a stable state 163b and change their orientation, but they remain in this state even after the electric field is turned off. or,
Each orientation state is maintained as long as the applied electric field Ea does not exceed a certain threshold value.

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

K-Otori 1” 1, 1 with a 1000-layer thick deposited O film
Prepare two glass plates with a thickness of m m, and apply N-methylpyrrolidone/n- ``Sunever 150J (trade name), manufactured by Yasan Kagaku Kogyo Co., Ltd., which is an alicyclic polyimide film forming liquid, on each glass plate. Butyl cellosolve = 3/1 (weight ratio)
A 3% solution of was applied for 30 seconds using a spinner with a rotation speed of 300 rpm. After the film was formed, a heating and baking treatment was performed at 25°C and 0°C for about 1 hour. The film thickness at this time was 500 people. This coating film was subjected to a unidirectional rubbing treatment using an acetate touch cloth. Thereafter, the glass plate was washed with isopropyl alcohol and dried at 120° C. for 20 minutes. After that, after scattering alumina beads with an average particle size of about 1.5 μm on one glass plate, two rubbing axes are parallel to each other and the rubbing directions are in the same direction.
A cell was created by stacking two glass plates.

Into this cell, rC3-1014J (trade name), a ferroelectric smectic liquid crystal manufactured by Chisso Corporation, is vacuum injected under the Tokichi phase, and then slowly cooled from the Tokichi phase to 30 °C at a rate of 0.5 °C/h. It was possible to orient it by doing this.

The phase change in the cell of this example using rC3-1014J was as follows.

In this cell, the C2-oriented domain existed stably at a temperature of about 50°C to -20°C, and the monodomain property was very good.

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

The above liquid crystal cell is sandwiched between a pair of 90° crossed nicol polarizers, a 50 μsec 30V pulse is applied, and the 90° crossed nicol is turned to the extinction position (darkest state).
The transmittance at this time was measured using a photomultiplier, and then a 30V pulse of 50 μsec was applied, and the transmittance at this time (bright state) was measured in the same manner. The transmittance was 1.0%, and the transmittance in the bright state was 8.0%.

Therefore, the contrast was 8.

In addition, a drop durability tester manufactured by Yoshihichi Seiki Co., Ltd. for the above-mentioned liquid crystal cell was used.
An impact durability test was conducted using DT-50J (trade name). At this time, the fall impact was 20G (G: gravitational acceleration 9.8
When the liquid crystal cell of this example was tested by increasing the IOG from "m/sec") in increments of IOG, the liquid crystal cell of this example did not cause any disturbance in alignment even when subjected to a drop impact of 80G. When applied, similar switching characteristics were obtained.

A cell was obtained in the same manner as in Example 1 except that the alignment control film and liquid crystal material shown in Table 1 were used.

Table 2 shows the contrast ratio and durability results obtained by conducting the same tests as in Example 1 for each sample.

Table 1 □ Arrangement” ト１鳳−□ ２ “Sunever 150J (Product name) rC
S-1ot month (product name)-8 Manufactured by Sankagaku Kogyo Co., Ltd.
-Chisso FLC3rsE4110J (product name)
rCS-1014J (Product name) - Alicyclic polyimide manufactured by the company - FLC4rs manufactured by Chitsuso Corporation
E4110J rCS-101
1J5 rJIG-IJ (Product name)
rCS-1014J-Nippon Synthetic Rubber Co., Ltd. Alicyclic Polyimide 6 rLP-Sashi” (Product Name) rC
S-1014J - Aromatic polyimide manufactured by Toshi Co., Ltd. ([FLcJ in the table means ferroelectric smectic liquid crystal] Table 2 (Measured at a temperature of 25°C; rGJ in the table is gravitational acceleration 9.
8 m/sec") Next, the phase transition temperature of the cell of this example was measured, and the results were as shown in Table 3 below.

Table 3 (Units in the table are °C) 2 91 78 55 52
50 0 or less 3 80.5 69.1 5
4 52 51 -204 91
78 55 53 51 0
Below 5 80.5 69.1 54 52
51 -206 80.5 69.1
54 53 51 -20 According to Table 3, Sm*c,/C2 phase transition point and Sm*c,/C2
It can be seen that the -3m*C2 phase transition point shows a cell-specific value and appears differently for each cell.

Next, the cells of Examples 1 to 6 were subjected to 50 μsec of 3
After applying a 0 V pulse, setting the 90° crossed nicols to the extinction position both produced a black state, and then after applying a 30 V pulse of 50 p sec.
When I set the 90° crossed nicol to the extinction position again,
Again, it was confirmed that both were in a black state (measurement temperature: 25° C.).

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

Contrast ratio and durability results were obtained for each cell. The results are shown in Table 5.

Table 4 □ Arrangement "Lll, LUuL lrSP-71O" (Product name) "C8-1017" (Product name) - Aromatic polyimide manufactured by Toshi Co. - F manufactured by Chitsuso Co., Ltd.
LC2rSP-710J rC3-
1018J (Product name) - Chisso FLC 3rX -419BJ (Product name) rC3 -
1017J-Nitto Denko Polyimide 4 rX-419BJ rC
3-1018J5 rX-419BJ
rC3-1014J Table 5 (Measured at a temperature of 25° C.) Next, the phase transition temperature of this comparative example cell was measured, and the results were as shown in Table 6 below.

Table 6 (Units in the table are °C) 1 66.4 62.5 52.8 -
- - (No expression of SmC2 2 74.5 71.7 58 -
- - (No expression of S or C2) 3 66.4 62.5 52.8 -
--(No expression of SmC2) 4 74.5 71.7 58-(SmC2
(No expression of Sm*C2) As can be seen from Table 6, none of the comparative cells had a temperature range that produced Sm*C2.

Next, the cells of Comparative Examples 1 to 5 were exposed to 3
After applying a 0V pulse, setting the 90° crossed nicols to the extinction position produced a blue state in both cases, and then after applying a 30V pulse of 50 μSec, the 90″ crossed nicols were set to the extinction position again. When set, it was confirmed that both were in a blue state (measurement temperature 25°C).This point is different from the two states of extinction position in Examples 1 to 6, and the orientation state is also different. It turned out that

Comparison I" A liquid crystal cell was prepared in the same manner as in Example 1, except that the rubbing treatment was applied in parallel to the upper and lower glass substrates in opposite directions, and measurements were performed in the same manner as in Example 1. ,
The results shown in Table 7 below were obtained.

Table 7 (measured at a temperature of 25°C) Next, after applying a 50 μsec 30 V pulse to this comparative example cell and setting 900 crossed Nicols at the extinction position, a black state was produced, followed by a 50 μsec pulse. 3
After applying a 0 V pulse, the 90' crossed nicol was set to the extinction position again, and a blue state was confirmed (measurement temperature: 25° C.). In this regard, Examples 1-6
It was found that the two states of extinction position were different from each other, and their orientation states were also different.

According to the results of the impact tests conducted in Comparative Examples 1 to 6 above,
Most of the alignment disturbances that occurred were sanded φ textures, and no switching occurred due to the application of 30 V and -30 V pulses of 50 μSec.

〔Effect of the invention〕

As can be seen from the above Examples and Comparative Examples, the present invention can provide improved impact resistance stability compared to conventional ferroelectric liquid crystal pulses, and can also provide a display screen with improved contrast. can.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a liquid crystal element of the present invention. Figure 2~
FIG. 6 is a sketch of a micrograph showing the temperature dependence of the ferroelectric liquid crystal alignment state. FIG. 7(A) is a plan view schematically showing the c-aligned domain and the C2-oriented domain, and FIG. 7(CB) is a cross-sectional view thereof. FIG. 7(C) is a plan view schematically showing another c-oriented domain and a C2-oriented domain, and FIG. 7(D) is a cross-sectional view thereof. 8th
FIG. 8(A) is a schematic diagram of the c-direction, and FIG. 8(B) is a photographic diagram showing the C-director. Figure 9(A) is
This is a schematic diagram of the C2 orientation, and FIG. 9(B) is a photographic diagram showing the C-director thereof. FIG. 10(A) is a schematic diagram showing a conventional orientation state, and FIGS. 10(B) and (C) are photographic diagrams showing the C-director. Figures 11 to 14
The figure shows c, the orientation domain and the C2 orientation domain;
It is a sketch diagram of a microscopic photograph. FIG. 15 is a perspective view schematically showing the operation of a 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. Figure 5 ゛(10810''') @ Figure 7"E T lightning defect 7 pin defect Figure 6 Figure 12/zl Y missing r self Figure 74 Figure 15

Claims (21)

[Claims] (1) a, a pair of substrates provided with a uniaxial alignment treatment axis; b, a bistable orientation state that is disposed between the pair of substrates and differs between the high temperature side and the low temperature side within the ferroelectric smectic phase; c. a ferroelectric smectic liquid crystal element having a means for optically identifying the bistable alignment state; . (2) The liquid crystal element according to claim 1, wherein the alignment state on the low temperature side is an alignment state that occurs at a temperature of 30° C. or higher when the temperature is lowered. (3) The liquid crystal element according to claim 1, wherein the alignment state on the low temperature side is an alignment state that occurs at a temperature of 40° C. or higher when the temperature is lowered. (4) The liquid crystal device according to claim 1, wherein the ferroelectric smectic phase is a chiral smectic C phase. (5) a, a pair of substrates provided with uniaxially oriented axes, the uniaxially oriented axes being parallel or substantially parallel to each other, and with the axes in the same direction; b; A ferroelectric smectic liquid crystal in a bistable alignment state that tends to generate a pair of coupled hairpin defects and a lightning defect, which generates a lightning defect at the front and a hairpin defect at the rear according to the direction of the uniaxial alignment treatment axis. A ferroelectric smectic liquid crystal device having c. a ferroelectric smectic liquid crystal having an orientation state exhibiting developmental order, and c. means for optically distinguishing said bistable state. (6) The liquid crystal element according to claim 5, wherein the area occupied by the domain in the orientation state exhibiting the generated order has a size that allows the domains in the orientation state exhibiting other generated order to be ignored. (7) The liquid crystal element according to claim 5, wherein the domain in an orientation state exhibiting the generated order has an occupied area generated by growing the domain in an orientation state exhibiting another generation order at a reduced temperature to a size that can be ignored. . (8) Under the temperature decrease, the temperature range in which the domains in the other orientation state exhibiting the other developmental order occupy an area of a size that cannot be ignored is higher than the temperature range in which the domains occupy an area of a size that is negligible. 8. The liquid crystal element according to claim 7, wherein the temperature range is 1/5 or less. (9) Under the temperature decrease, the temperature range in which domains in the other orientation state exhibiting the other developmental order occupy an area of a non-negligible size is greater than the temperature range in which the domains occupy an area of a size negligible. 8. The liquid crystal element according to claim 7, wherein the temperature range is 1/10 or less. (10) Under the temperature decrease, the temperature range in which the domains in the other orientation state exhibiting the other developmental order occupy an area of a size that is not negligible is greater than the temperature range in which the domains occupy an area of a size that is negligible. 8. The liquid crystal element according to claim 7, wherein the temperature range is 1/20 or less. (11) The liquid crystal element according to claim 7, wherein the lower limit temperature at which the domain in the orientation state exhibiting the other generated order occupies a non-negligible area under the temperature decrease is 30° C. or higher. (12) The liquid crystal element according to claim 7, wherein the lower limit temperature at which the domain in the orientation state exhibiting the other generated order occupies a non-negligible area under the temperature decrease is 40° C. or higher. (13) Claim 6, wherein the domain in an oriented state exhibiting the other generated order is generated in a region near the sealing material, and the domain in the oriented state exhibiting the generated order is generated inside the neighboring region.
liquid crystal element. (14) The liquid crystal element according to claim 6, wherein the other generated order is an order that generates lightning defects at the front and hairpin defects at the rear according to the direction of the uniaxial alignment treatment axis. (15) The liquid crystal element according to claim 5, wherein the two states at the extinction position of the domain in the alignment state exhibiting the generated order are optically equivalent. (16) The liquid crystal element according to claim 5, wherein the uniaxial alignment treatment axis is provided to an alignment control film formed on a substrate. (17) Claim 16, wherein the alignment control film is formed of a polyimide film, a polyamide film, or a polyester film.
liquid crystal element. (18) The liquid crystal element according to claim 16, wherein the alignment control film is formed of a polyimide film. (19) The liquid crystal element according to claim 16, wherein the alignment control film is a film provided on an insulating film formed on a substrate. (20) The liquid crystal element according to claim 5, wherein the uniaxial alignment treatment axis is a rubbing treatment axis. (21) The liquid crystal device according to claim 5, wherein the ferroelectric smectic liquid crystal is of chiral smectic C phase.