JPS61205920A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To improve initial orientability by providing plural structural members having side walls to one substrate into a stripe shape, subjecting the other substrate to an orientation treatment in the direction parallel with or perpendicular to the extension direction of said members and using a specific liquid crystal compsn. CONSTITUTION:The structural members 104 having the stripe-shaped side walls 106, 107 are disposed to one substrate 101 of a pair of the electrode substrates 101, 110. The other substrate 110 is subjected to a uniaxial orientation treatment and the treatment direction thereof is controlled to the direction parallel or orthogonal with the extension direction of the members 104. The liquid crystal compsn. incorporated therein with one kind of a liquid crystal of which the phase transfers from a Ch phase to an Sm*phase in the course of a temp. fall and at least one kind of a liquid crystal of which the phase transfers from an isotropic phase to the Ch phase and crystal phase in the course of the temp. fall or from the isotropic phase to the Ch phase, Sm phase and crystal phase in the course of the temp. fall is used. The liquid crystal element made into the construction in which the operation of the element based on the bistability of the ferroelectric liquid crystal and the mono-domain characteristic of the liquid crystal layer are compatible is obtd. by such constitution and the defect at the spacer edge is eliminated even in the storage state in which the defect is particularly liable to appear.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a liquid crystal element applied to a liquid crystal display element, a liquid crystal-optical shutter array, etc. This invention relates to a liquid crystal element with improved display and driving characteristics.

[Conventional technology]

As a conventional liquid crystal element, for example, M-Shut (M,
5chadt) and Double Φ Helfrich (W, He
``Applied Physics Let's'' by 1frich)
ter5''') Volume 18, No. 4 (February 15, 1971
``Voltage Dependant Optical Number Activity Ichiban of φ'' on pages 127-128
A Twisted Φ Nematic Liquid Crystal” (“Voltage Dependent Op.
T i cal Activity of
a TwisLed Nematic Li
The twisted Φ nematic shown in
matic) devices using liquid crystal are known. This TN liquid crystal has a problem in that crosstalk occurs during time division driving using a matrix electrode structure with high pixel density, so the number of pixels is limited.

Furthermore, a display element is known in which a switching element using a thin film transistor is connected to each pixel, and each pixel is switched. However, the process of forming the thin film transistor on the substrate is extremely complicated, and it is difficult to use a display element with a large area. There are some problems that make it difficult to create.

To improve the drawbacks of conventional liquid crystal devices, the use of bistable liquid crystal devices is proposed by Clark (C1
As a liquid crystal having bistability, chiral smectic C is generally proposed as a liquid crystal having bistability. A ferroelectric liquid crystal having a phase (SmC)jc) or an H phase (SmH)k) is used.

This liquid crystal has a bistable state consisting of an optically stable state of $1 and a second optically stable state in response to an electric field. Therefore, unlike the optical modulation element used in the above-mentioned TN type liquid crystal, The liquid crystal is aligned in a first optically stable state with respect to the electric field vector, and the liquid crystal is aligned in a second optically stable state with respect to the other electric field vector. In addition, this type of liquid crystal responds to an applied electric field and very quickly responds to the above-mentioned
It has the property of taking one of two stable states and maintaining that state when no electric field is applied. By utilizing such properties, many of the problems of the conventional TN type device described above can be significantly improved. This point will be explained in more detail below in connection with the present invention. However, in order for this ferroelectric liquid crystal with bistability to exhibit predetermined driving characteristics, the liquid crystal placed between a pair of parallel substrates must be in the above two stable states, regardless of the applied state of the electric field. It is necessary that the molecules be arranged in such a state that conversion between them can occur effectively.

For example, for a ferroelectric liquid crystal with SmC* or SmH* phase, the liquid crystal molecular layer with SmC* or SmH)k phase is perpendicular to the substrate plane.

Therefore, it is necessary to form a region (monodomain) in which the liquid crystal molecular axes are arranged substantially parallel to the substrate surface. However, in conventional ferroelectric liquid crystal devices with bistability, the alignment state of the liquid crystal having such a domain structure is as follows.

The reality is that sufficient characteristics could not be obtained because the formation was not always satisfactory.

For example, according to C1ark et al., methods of applying a magnetic field, methods of applying a shear force, and methods of applying a parallel ridge between the substrates in order to provide such an orientation state are described.
) have been proposed. However, none of these methods necessarily gave satisfactory results. For example, the method of applying a magnetic field is
There are disadvantages in that it requires large-scale equipment and is incompatible with thin-layer cells with good operating characteristics.Also, the method of applying shear force is incompatible with the method of injecting liquid crystal after creating the cell. There are some difficulties. Furthermore, the method of arranging parallel ridges within a cell cannot provide a stable alignment effect by itself.

[Problems to be Solved by the Invention] In view of the above-mentioned circumstances, an object of the present invention is to solve the problem of potential problems as a display element having high-speed response, high-density pixels, and a large area, or an optical scanner having a high shutter speed. The purpose of the present invention is to provide a ferroelectric liquid crystal element that can fully exhibit its characteristics by improving monodomain formation or initial orientation, which has been a problem in the past. .

[Effect]

As a result of research in line with the above-mentioned objective, the present inventors have found that the surface of at least one of a pair of parallel substrates sandwiching a liquid crystal has a uniaxial alignment treatment effect by rubbing etc. In addition to utilizing the effect of the arrangement of structural members having shaped side walls, at least one type of liquid crystal that undergoes a phase transition from a cholesteric phase to a chiral smectic phase during the cooling process, and from an isotropic phase to a cholesteric phase and a crystalline phase during the cooling process. The smectic phase of a liquid crystal composition containing at least one type of liquid crystal that undergoes a phase transition from an isotropic phase to a cholesteric phase, a smectic phase, and a crystalline phase during the temperature cooling process, such as SmA (smectic A).
phase), chiral smectic phase, etc., from a phase on the higher temperature side than the smectic phase, such as a cholesteric phase (chiral nematic phase), a nematic phase, or an isotropic phase. It has been found that as a result, a liquid crystal device can be obtained with a structure that allows both the operation of the device based on the bistability of the ferroelectric liquid crystal and the monodomain property of the liquid crystal layer.

[Means for solving problems]

The liquid crystal element of the present invention is based on the above-mentioned findings,
More specifically, in a liquid crystal element in which a liquid crystal is sandwiched between a pair of parallel substrates, a first substrate of the pair of parallel substrates has a plurality of structures each having a side wall on the side that contacts the liquid crystal. The members are arranged in a stripe pattern, and the surface of the second substrate in contact with the liquid crystal is subjected to uniaxial alignment treatment in a direction substantially parallel or perpendicular to the extending direction of the plurality of structural members on the first substrate. and at least one kind of liquid crystal that undergoes a phase transition from a cholesteric phase to a chiral smectic phase during the cooling process, and from an isotropic phase to a cholesteric phase and a liquid crystal phase during a cooling process, or from an isotropic phase to a cholesteric phase during a cooling process. is characterized in that the smectic phase of a liquid crystal composition containing a smectic phase and at least one type of liquid crystal that undergoes a phase transition to the crystalline phase is formed by a phase transition caused by slow cooling from a phase on the higher temperature side than the smectic phase. are doing.

〔Example〕

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

The liquid crystal used in the present invention has a ferroelectric property, and specifically has a chiral smectate C phase (SmC tree).
, H phase (SmH)k), I phase (SmI*), J phase (Sm
J) k), phase (SmK*), phase G (SmG*) or F
A liquid crystal having a phase (SmF')k) can be used.

Table 1 shows specific examples of liquid crystals that undergo a phase transition from an isotropic phase to a cholesteric phase to a chiral smectate phase (i.e., a liquid crystal that exhibits a chiral smectate phase) during the temperature cooling process. Table of liquid crystals that undergo a phase transition from an isotropic phase to a cholesteric phase and a crystalline phase or from an isotropic phase to a cholesteric phase, SmA, and a crystalline phase (i.e., a liquid crystal that exhibits a cholesteric phase) 1 Specifications of a liquid crystal that exhibits a cholesteric phase Examples (compound name, structural formula and phase transition point) biphenyl-4'-carboxylate biphenyl-4'-lupoxylate-2-chloro-1,4-phenyl diamine Table 2 Specific examples of liquid crystals exhibiting cholesteric phase (Compound name, structural formula and phase transition point) (A) Cholesteryl propionate 107°C
117℃ Crystal ;= Cholesteric phase ;= Isotropic phase (B)
Cholesteryl annanate (C) Cholesteryl palmitate (D)
Cholesteryl benazonate crystal ;= cholesteric phase ;= isotropic phase 4-(2''-methylbutyl)-4'-
Cyanobiphenyl SmA 4++++++ 1L=X
Telic phase '-30℃ -54℃ 4-(2''-methylbutyloxy)-4'-cyanobiphenyl crystal ;= cholesteric phase ;= isotropic phase 4
-Cyanobenzylidene-4'-(2-methylbutyl)aniline 4-(2-methylbutyl)-4'-hexyloxyazobenzene crystal ;= cholesteric phase ;=
Isotropic phase 4-(2-methylbutyl)phenyl-4'-desyloxybenzoate 4-hemosiloxy-4'-(2
-Methylbutyl)benzoate Two or more of these liquid crystals exhibiting a chiral smectate phase or liquid crystals exhibiting a cholesteric phase may be used in combination.

In the liquid crystal composition used in the present invention, the ratio of the liquid crystal exhibiting the above-mentioned chiral smectic phase to the liquid crystal exhibiting the above-mentioned cholesteric phase varies depending on the type of liquid crystal used;
Liquid crystal 1 that generally exhibits the above-mentioned chiral smectic phase
The amount of the liquid crystal exhibiting the cholesteric phase is 0.1 to 50 parts by weight, preferably 1 to 20 parts by weight, per 0.00 parts by weight.

When constructing an element using these materials.

In order to maintain the temperature state such that the liquid crystal compound becomes an SmC* phase or an SmH wood phase, the element can be supported by a copper block or the like in which a heater is embedded, if necessary.

FIG. 1 schematically depicts an example of a cell for explaining the operation of a ferroelectric liquid crystal. 21a and 21b are In2
O3, 5n02 or ITO (Indium-Tin
It is a substrate (glass plate) coated with a transparent electrode made of a thin film such as
SmC* phase or S which is oriented perpendicular to the glass surface
mH* phase liquid crystal is sealed. Thick line 23
represents liquid crystal molecules.

This liquid crystal molecule 23 has a ``dipole moment CP'' 24 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 21a and 21b, the helical structure of the liquid crystal molecules 23 is unraveled, and the liquid crystal molecules 23 are aligned so that the dipole moment (P) 24 is all oriented in the direction of the electric field. Can change direction.

The liquid crystal molecules 23 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, the voltage application polarity can be changed. It is easily understood that the liquid crystal optical modulation element has optical characteristics that change depending on the amount of the liquid crystal.

The liquid crystal cell preferably used in the liquid crystal element of the present invention can have a sufficiently thin thickness (for example, 101 L or less).
As shown in Figure 2, even when no electric field is applied, the helical structure of the liquid crystal molecules unwinds and assumes a non-helical structure, and its dipole moment (Pa or pb) is either upward (34a) or downward (34b). takes the state of When an electric field Ea or Eb of different polarity above a certain threshold value is applied to such a cell by the voltage applying means 31a and 31b as shown in FIG. 2, the dipole moment is
upward in response to the electric field vector of! t34a or downward 3
4b, and accordingly, the liquid crystal molecules are oriented to either the first stable state 33a or the second stable state 33b.

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, and 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, the electric field Ea
When the voltage is applied, the liquid crystal molecules are aligned in a first stable state 33a, and this state remains stable even when the electric field is turned off. When an electric field Eb in the opposite direction is applied, the liquid crystal molecules are oriented to a second stable state 33b and change their orientation, but they remain in this state even after the electric field is turned off. Also, the electric field E
As long as a does not exceed a certain threshold, each orientation state is maintained. Such fast response speed and
In order to effectively realize bistability, it is preferable that the cell be as thin as possible.

The biggest problem in forming devices using liquid crystals with such ferroelectricity is, as mentioned earlier, that SmC
*phase or SmH) It is difficult to form a highly monodomain cell in which a layer having a k phase is aligned perpendicularly to the substrate surface and liquid crystal molecules are aligned approximately parallel to the substrate surface, The main purpose of the present invention is to solve this problem.

FIGS. 3(A) to 3(C) show an embodiment of the liquid crystal element of the present invention. FIG. 3(A) is a perspective view of the same embodiment, FIG. 3(B) is a side sectional view thereof, and FIG. 3(C) is a front sectional view thereof. However, in Figure 3 (A),
Illustrations of liquid crystal and polarizer are omitted. .

In m3ffl (A) to (C), an electrode group (for example, forming a scanning electrode group) consisting of a plurality of electrodes 102 is placed on a substrate lot made of a glass plate or a plastic plate.
is formed in a predetermined pattern by etching or the like. Furthermore.

A plurality of side walls 106 and 107 are arranged in a stripe shape in a positional relationship that is alternately and parallel to these electrodes 102.
A spacer member 104 is formed.

Furthermore, an insulating film 103 is formed to cover the electrode 102 except for the area where the spacer member 104 is formed on the substrate 101.

The spacer member 104 is made of polyvinyl alcohol, for example.
Polyimide, polyamideimide.

Polyesterimide, polyparaxylylene, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin.

Resins such as melamine resin, urea resin, acrylic resin, photosensitive polyimide, photosensitive polyamide, cyclized rubber photoresist, phenol novolak photoresist, or electron beam photoresist (polymethyl methacrylate, epoxidized-1, 4) -polybutadiene, etc.).

The insulating film 103 has a function of preventing charge injection from the electrode 102 to the liquid crystal layer, and is made of, for example, silicon oxide, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride. It can be obtained by forming a film by vapor deposition using a compound such as silicon carbide or boron nitride. In addition, for example, polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyparaxylylene, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, yurya resin. It can also be formed as a coating film of resin such as or acrylic resin. The thickness of the insulating film 103 depends on the charge injection prevention ability of the material and the thickness of the liquid crystal layer, but is usually 50 to 5, preferably 500 to 5,000.
Set within the range of people. On the other hand, the thickness of the liquid crystal layer depends on the ease of alignment peculiar to the liquid crystal material and the response speed required for the element, but is determined by the height of the spacer member 104, and is usually 0.2μ to 200p, preferably is 0-5p
It is set in the range ending in L-10. Moreover, the spacer member 10
The width of 4 is usually 0.5 ru 50 colors, preferably IJL ~ 2
It is set in the range of 0IL. If the pitch (distance) of the spacer members 104 is too large, it will inhibit the uniform alignment of liquid crystal molecules, while if it is too small, the effective area as a liquid crystal optical element will decrease.
The pitch is set at 2 mm, preferably in the range of 50 to 700 P.

These spacer members 104 are formed into predetermined patterns and dimensions by various printing methods such as screen printing, or more preferably by techniques such as photolithography and electron beam lithography.

The liquid crystal element of the present invention includes the substrate 101 processed as described above and another substrate 110 stacked in parallel, and a plurality of electrodes (for example, signal electrodes) 111 are provided on this substrate 110. An insulating film 112 is further formed on the electrode group. Multiple (signal) electrodes 11
1 and the other plurality of (scanning) electrodes 102 can be wired in a matrix structure. The insulating film 1112 on the substrate 110 prevents the generation of current flowing through the liquid crystal layer 105, similar to the above-mentioned insulating film 103, and is made of a film formed of the same material as the above-mentioned insulating film 103.
According to the present invention, the plane 113 formed by the insulating film 112 of this substrate 101 is subjected to uniaxial orientation treatment, and the orientation direction is approximately parallel to the extending direction of the spacer member 104 on the substrate lot (i.e., between these two directions). The angle θ formed by these two directions is preferably O°≦15°) or orthogonal (preferably 80＠θ<100'). In this case, when the angle θ formed by these two directions is orthogonal, the liquid crystal cell is , there is a greater tendency for alignment defects to occur compared to a liquid crystal cell when the angle θ is parallel, and especially when a lower rubbing process is applied as a uniaxial alignment treatment, the liquid crystal cell with the angle θ parallel has a greater tendency to cause alignment defects. Compared to a liquid crystal cell in which θ is orthogonal, monodomains with no alignment defects can be formed.According to the research of the present inventors, if such a parallel or orthogonal relationship is not satisfied, the liquid crystal will form at the edge of the spacer. In cells with disordered molecular orientation or memory function, switching between bistable states may not be performed properly. However, as can be seen from the range expression of θ above,
A deviation of up to about 15° poses no practical problem. Such uniaxial alignment treatment can be achieved by rubbing the insulating film 112 with velvet, cloth, paper, or the like, or by diagonally depositing the insulating film 112, as is well known for TN-type liquid crystal cells. I can do it.

Note that the above-described uniaxial alignment treatment basically does not need to be performed on the substrate 101, but it can be performed on the substrate 101 as well.
After uniaxial orientation treatment approximately parallel or orthogonal to the extension direction of 4.

The insulating film 103 is formed by a base layer, or the insulating film 1
By performing a uniaxial orientation treatment after forming the spacer member 103 and then selectively removing the orientation treatment effect on the surface 10B formed by the insulating film 103, the side walls 106 and 1 of the spacer member 104 are
It is desirable to selectively impart an alignment treatment effect to 07 in order to increase the response speed of the obtained liquid crystal element.

The liquid crystal element of the present invention includes a pair of parallel substrates 101 and 110.
A pair of polarizing means (polarizer 114 and analyzer 115) sandwiching the substrates 101 and 110 can be used. As the polarizer 114 and the analyzer 115, ordinary polarizing plates, polarizing films, or polarizing beam splitters can be used. In this case, the polarizing means can be arranged in a crossed Nicols state or a parallel Nicols state. be.

In the liquid crystal element of the present invention, a pair of parallel substrates are fixed so as to satisfy the mutual relationship between the extension direction of the spacer member and the uniaxial alignment treatment direction, and their periphery is sealed with an epoxy adhesive or low melting point glass. After that, a ferroelectric liquid crystal is sealed and heated to an isotropic phase, and then slowly cooled while precisely controlling the temperature.

In the above, the liquid crystal element of the present invention has been explained based on one preferred embodiment thereof. However, it is possible to make various modifications to the above embodiments within the scope of the present invention.
It's easy to understand. For example, the member described as the spacer member 104 in the above example can also function as a spacer member by contacting both of the pair of parallel substrates, if it has a side wall to exert the necessary wall effect on the liquid crystal. You don't have to.

However, as can be seen from the above example, the spacer member is an example of a preferable structural member, and it is also possible to use a modified stripe-shaped spacer in which the spacer member 104 is arranged in a dot shape along a straight line. Further, the electrodes are not limited to the above-described simple striped matrix electrodes, but may be formed in other shapes, for example, electrode wiring having a 7-segment structure.

A specific manufacturing example of the optical modulation element of the present invention will be described below.

Example 1 Pair (7) I To (I nd i un-Tin
A polyimide film having a thickness of about 1,500 layers was formed on one side of the substrate on which a striped pattern electrode made of (Oxide) was formed, and rubbed in one direction. In addition, a polyimide film with a film thickness of 2 pm was formed on the other substrate.
By photo-etching, the width is 20mm with a pitch of 200gm.
A striped spacer of Bm was formed.

As the polyimide, 5P-510 manufactured by Toshisha Co., Ltd. was used, and its N-methylpyrrolidone solution was applied by dipping or spinner coating to form a polyimide film.

Etching was performed using a mixture of hydrazine: Na0H=l:l as an etching solution, and heating it to 30°C.
The substrate on which the polyimide film was formed was immersed for 3 minutes to perform etching.

A liquid crystal cell (cell thickness: 2 pm) was constructed by aligning the direction of the striped spacer and the rubbing direction of the pair of electrode substrates produced in the above steps substantially parallel to each other.

After injecting the following composition A in an isotropic phase into this liquid crystal cell,
The temperature of the cell was slowly cooled at a rate of 5° C./hour to create an SmC* liquid crystal cell. When this SmC* liquid crystal cell was observed with a polarizing microscope, it was found that monodomains with a non-helical structure were formed without any alignment defects.

4-hexyloxyphenyl-4-(2''-methylbutyl)biphenyl-4'-rupoxylate
100 parts by weight cholesteryl nonanate
5 parts by weight Examples 2 to 7 In place of composition A used in Example 1, the following composition B was used.
(Example 2), C (Example 3), D (Example 4), E (
Example 5), F (Example 6), and G (Example 7) were used, but liquid crystal cells were created in exactly the same manner as in Example 1, and each S m C * liquid crystal cell was polarized. When observed under a microscope, a non-helical monodomain format with no orientation defects was confirmed in all cases.

1 place 1"4-octyloxyphenyl-4-(2"-methylbutyl)biphenyl-4'-rupoxylate
ioo parts by weight 4-(2-methylbutyl)phenyl-4'-desyloxybenzony) 10 parts by weight 1 animal 4-year-old cutyloxyphenyl-4-(2''-methylbutyl)biphenyl-4'-carboxylate
100 parts by weight 4-(2″-methylbutyl)-
4'-cyanobiphenyl 10 parts by weight 4-octyloxyphenyl-4-(2''-methylbutyl)biphenyl-4'-cyanoboxylate
100 parts by weight cholesteryl benzonate
10 parts by weight 4-octyloxyphenyl-4-(2''-methylbutyl)biphenyl-4'-rupoxylate
100 parts by weight 4-(2''-methylbutyloxy)-4'-cya/biphenyl io parts by weight Tadayan 11 4-hexyloxyphenyl-4-(2''-methylbutyl)biphenyl-4'-carboxylate
100 parts by weight 4-(2-methylbutyl)-r
-Hexylocyazobenzene 4 parts by weight on the skin 4-octyloxyphenyl-4-(2''-methylbutyl)biphenyl-4'-rupoxylate
100 parts by weight 4-cyanobenzylidene-4'
-(2-Methylbutyl)aniline 4 parts by weight Example 8 A polyimide film with a thickness of about 1500 was formed on one of the substrates on which a pair of striped pattern electrodes made of ITO was formed, and rubbed in one direction. did. A polyimide film with a thickness of 2JLm was formed on the other substrate, and photoetched to a width of 20.2JLm at a pitch of 200gm.
pm striped spacers were formed and rubbed in parallel to the direction of the striped spacers.

As the polyimide, 5P-510 manufactured by Toshisha Co., Ltd. was used, and its N-methylpyrrolidone solution was applied by dipping or spinner coating to form a polyimide film.

Etching was performed using a mixture of hydrazine and Na0H=l:1 as an etching solution, and heating it to 30°C.
The substrate on which the polyimide film was formed was immersed for 3 minutes to perform etching.

A pair of electrode substrates created using the above process.

A liquid crystal cell (cell thickness: 21 Lm) was constructed by making the direction of the striped spacer and the rubbing direction substantially parallel to each other.

After injecting the isotropic phase composition A used in Example 1 into this liquid crystal cell, the temperature of the cell was slowly cooled at a rate of 5° C./hour,
A liquid crystal cell of SmC)k was created. When this SmC* liquid crystal cell was observed with a polarizing microscope, it was found that a monodomain with a non-helical structure was formed without any alignment defects.

Example 9 In Example 1, a liquid crystal cell was constructed in the same manner as in Example 1, except that a pair of substrates were combined so that the direction of their rubbing treatment was perpendicular to the extending direction of the striped spacer.

This liquid crystal cell was observed using a polarizing microscope.

Some alignment defects were observed near the edges of the striped spacers.

Example 1 A polyimide film having a thickness of about 1000 was formed on one of the substrates on which a pair of striped patterned electrodes made of ITO was formed, and a unidirectional rolling process was performed. A polyimide film with a thickness of 2 pm was formed on the other substrate, and a polyimide film with an upper lip of 1.900 μm and an m pitch of 4-ra width was formed by photo-etching.
A striped spacer of 0 Lm was formed.

As the polyimide, 5P-510 manufactured by Toshisha Co., Ltd. was used, and a solution of its N-methylpyrrolidone was applied by dipping or spinner coating to form a polyimide film.

Etching was carried out by using a mixed solution of hydrazine:NaOH=1:1 as an etching solution, raising the temperature to 30° C., and immersing the substrate on which the polyimide film was formed for 3 minutes.

A polyimide film similar to that described above was formed over the entire surface of the substrate on which the striped spacers were formed. However, the thickness of the polyimide film at this time was set to 1000.Next, the surface of this polyimide film was subjected to a rubbing treatment in a direction parallel to the extending direction of the striped spacer.

A pair of electrode substrates created using the above process.

A cell set (cell thickness: 2 h m) was prepared so that the rubbing directions were parallel to each other, composition A in an isotropic phase was injected into the cell, and SmC* with a non-helical structure was slowly cooled.
After creating mC upper file.

When observed in the same manner as in Example 1, similar results were obtained.

It was found that this liquid crystal cell formed stable monodomains that did not cause alignment defects in SmC)k even after being left for several days, compared to the liquid crystal cells used in other examples.

Furthermore, when this liquid crystal element was driven by applying a pulse signal of 1 m5e at 20 V, compared to the case of Example 1,
It was found that the contrast between the bright and dark states increases.

Comparative Example 1 When assembling the liquid crystal cell of Example 1, a pair of electrode substrates were stacked one on top of the other with the angle θ between the direction of the striped spacer and the rubbing direction set to 25°. A non-helical SmC* liquid crystal cell was prepared in the same manner as in Example 1.

When this SmC* liquid crystal cell was observed in the same manner as in Example 1, it was found that black streaks caused by countless alignment defects were observed near the edges of the striped spacers. This black stripe covers the electrode formation area, and even if two types of electrode signals with different polarities are applied between this pair of electrodes, no dual signals will be generated in the area where the black stripe is formed. It was found that it showed no stability.

Comparative Example 2 An electrode substrate identical to the one on which the striped spacer and polyimide film were provided was prepared when creating the liquid crystal cell of Example 10, and the surface of this polyimide film was coated in the direction of extension of the striped spacer. Rubbing treatment was performed at an angle of 25°.

Next, the same electrode substrate on one side as used in Example 10 was prepared, and rubbed in one direction.

These two electrode substrates were stacked so that their rubbing directions were parallel to each other, and then the cell was assembled. After that, a non-helical structure SmC)k liquid crystal cell was created in the same manner as in Example 1. When this liquid crystal cell was observed in the same manner as in Example 1, as in Comparative Example 1, alignment defects fatal to a display device were observed.

Furthermore, although an electric signal was applied between the pair of electrodes in the same manner as described above, no bistability was observed.

〔Effect of the invention〕

As described above, according to the present invention, a structural member (
A uniaxial alignment treatment (e.g., rubbing) is performed on the other substrate, and the direction of the treatment is regulated to be approximately parallel or perpendicular to the above-mentioned structural members. At least one type of liquid crystal that undergoes a phase transition from a phase to a chiral smectic phase, and from an isotropic phase to a cholesteric phase and a crystalline phase during a cooling process, or from an isotropic phase to a cholesteric phase, a smectic phase, and a crystalline phase during a cooling process. By using a liquid crystal composition containing at least one type of liquid crystal that produces such a phenomenon, it is possible to obtain a liquid crystal composition that is particularly susceptible to defects, such as opacity, brightness, and shading.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing a liquid crystal element using chiral smectic liquid crystal. FIG. 2 is a perspective view schematically showing the bistability of the liquid crystal element. Figure 3 (A)
3 is a perspective view of a liquid crystal element of the present invention, FIG. 3(B) is a side sectional view thereof, and FIG. 3(C) is a front sectional view thereof.

Claims (3)

[Claims] (1) In a liquid crystal element in which a liquid crystal is arranged between a pair of substrates, one of the pair of substrates has a plurality of structural members having sidewalls arranged in a stripe pattern, and At least one of the substrates is subjected to uniaxial alignment treatment in a direction substantially parallel or perpendicular to the extending direction of the plurality of structural members, and a liquid crystal that undergoes a phase transition from a cholesteric phase to a chiral smectic phase during a cooling process. A liquid crystal composition containing at least one type of liquid crystal and at least one type of liquid crystal that undergoes a phase transition from an isotropic phase to a cholesteric phase and a liquid crystal phase during a cooling process, or from an isotropic phase to a cholesteric phase, a smectic phase, and a crystalline phase during a cooling process. A liquid crystal element characterized in that a smectic phase is formed by phase transition from a phase on a higher temperature side than the smectic phase. (2) The plurality of structural members having the side walls function as stripe-like spacer members between the pair of substrates and have a thickness suitable for imparting bistability to the ferroelectric liquid crystal. The liquid crystal element according to item 1. (3) The angle θ formed between the extension direction of the plurality of structural members having the side walls and the uniaxial orientation processing direction is 0°≦θ<15
2. The liquid crystal element according to claim 1, which satisfies the relationship: 0.degree. or 80.degree.<.theta.<100.degree.