JPH06100752B2 - Liquid crystal element - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid crystal element applied to a liquid crystal display element, a liquid crystal-optical shutter array, or the like, and more specifically, by improving the initial alignment state of liquid crystal molecules, The present invention relates to a liquid crystal element having improved display and driving characteristics.

[Conventional technology]

As a conventional liquid crystal element, for example, M.Scatter (M.Sc
hadt) and W. Helfrich, "Applied Physics Redders"("Applied
Physics Letters ") Vol. 18, No. 4, (Published February 15, 1971), pages 127-128," Voltage Day Pendant Optical Activity of a Twisted Nematic Stick Liquid Crystal ""(" Volt
age Depen-dent Optical Activity of a Twisted Nemat
ic Liquid Crystal ”) is known, which uses twisted nematic liquid crystal. This TN liquid crystal is a cross-type when using time-division driving using a matrix electrode structure with high pixel density. The number of pixels is limited because of the problem of generating talk.

Further, there is known a display element of a type in which a switching element formed of a thin film transistor is connected to each pixel and each pixel is switched, but a step of forming a thin film transistor on a substrate is extremely complicated, and a large area display element is used. There are problems that are difficult to create.

The use of bistability-type liquid crystal elements is known as Clark (Cl
ark) and Lagerwall (JP-A-56-107216, US Pat. No. 4,367,924, etc.). Generally, a liquid crystal having bistability is a chiral smectic C phase (SmC ^* ) or H phase (SmC ^* ).
A ferroelectric liquid crystal having H ^* ) is used.

This liquid crystal has a bistable state consisting of a first optical stable state and a second optical stable state with respect to an electric field, and therefore,
Unlike the optical modulation element used in TN type liquid crystal, for example, the liquid crystal is aligned in the first optical stable state with respect to one electric field vector and the second optical stable with respect to the other electric field vector. The liquid crystal is aligned in the state. In addition, this type of liquid crystal responds to an applied electric field very quickly in accordance with the above-mentioned 2
It has the property of taking one of the two stable states and maintaining that state when no electric field is applied. By utilizing such a property, a considerable substantial improvement can be obtained with respect to many of the problems of the above-mentioned conventional TN type element.
This will be explained in more detail below in connection with the present invention. However, in order for the ferroelectric liquid crystal having this bistability to exhibit a predetermined driving characteristic, the liquid crystal disposed between the pair of parallel substrates should have the two stable states described above regardless of the electric field application state. It is necessary that the molecular arrangement is such that the conversion between the two occurs effectively. For example SmC
^* Or SmC ^* for ferroelectric liquid crystal having SmH ^* phase
Alternatively, it is necessary to form a region (monodomain) in which the liquid crystal molecular layer having the SmH ^* phase is perpendicular to the substrate surface, and therefore the liquid crystal molecular axes are arranged substantially parallel to the substrate surface. However, in the conventional ferroelectric liquid crystal device having bistability, the alignment state of the liquid crystal having such a domain structure was not always formed satisfactorily, so that the actual characteristics could not be obtained. Is.

For example, according to Clark et al., A method of applying a magnetic field, a method of applying a shearing force, a method of arranging parallel ridges at small intervals between substrates, and the like are proposed in order to give such an orientation state. Has been done. However, none of these gave necessarily satisfactory results. For example, the method of applying a magnetic field has a drawback in that it requires a large-scale device and is incompatible with a thin layer cell having good operating characteristics. There is a drawback that it is not compatible with the method of injecting liquid crystal. In addition, the method of arranging parallel ridges in the cell cannot give 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 a ferroelectric liquid crystal having potential suitability as a display element having high-speed response, high-density pixels and a large area, or an optical shutter having high shutter speed. It is an object of the present invention to provide a ferroelectric liquid crystal device capable of sufficiently exhibiting its characteristics by improving monodomain forming property or initial alignment property which has been a problem in the conventional device.

[Action]

As a result of research conducted along the above-mentioned object, the present inventors have found that the surface of at least one of the pair of parallel substrates holding the liquid crystal has a uniaxial alignment treatment effect by rubbing or the like and a stripe arranged between the pair of substrates. With the effect of the arrangement of the structural members having a cylindrical side wall, and a smectic phase of a liquid crystal composition containing at least a liquid crystal exhibiting a chiral smectic phase and a liquid crystal exhibiting at least a nematic phase, for example, SmA (smectic A phase) , A chiral smectic phase, etc., on a higher temperature side than the smectic phase,
For example, when a cholesteric phase (chiral nematic phase), a nematic phase, or a phase transition by slow cooling from an isotropic phase is used, a smectic phase monodomain can be formed, which results in the bistability of the ferroelectric liquid crystal. It has been found that a liquid crystal device having a structure in which the operation of the device based on the above and the monodomain property of the liquid crystal layer are compatible can be obtained.

[Means for solving problems]

The liquid crystal element of the present invention is based on the above findings,
More specifically, in a liquid crystal element in which liquid crystal is sandwiched between a pair of parallel substrates, a plurality of structures each having a side wall on the surface of the first substrate of the pair of parallel substrates which is in contact with the liquid crystal are provided. The members are arranged in stripes, 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. The liquid crystal composition containing a liquid crystal exhibiting a chiral smectic phase and a liquid crystal exhibiting at least a nematic phase has a smectic phase formed by a phase transition by slow cooling from a phase on a higher temperature side than the smectic phase. It has features.

〔Example〕

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

The liquid crystal used in the present invention has ferroelectricity, and specifically, is a chiral smectic C phase (SmC ^* ),
H phase (SmH ^* ), I phase (SmI ^* ), J phase (SmJ ^* ), K phase (Sm
A liquid crystal having K ^* ), G phase (SmG ^* ) or F phase (SmF ^* ) can be used.

Specific examples of the liquid crystal that can be used in the ferroelectric liquid crystal device of the present invention are as follows.

Table 1 shows specific examples of liquid crystals showing a chiral smectic phase used in the liquid crystal composition of the present invention. On the other hand, Table 2 shows specific examples of the liquid crystal exhibiting the nematic phase.

Two or more kinds of these liquid crystals exhibiting a chiral smectic phase or liquid crystals exhibiting a nematic phase can be used in combination.

The ratio of the liquid crystal showing the chiral smectic phase and the liquid crystal showing the nematic phase in the liquid crystal composition used in the present invention is different depending on the kind of the liquid crystal used, but generally 100 weight% of the liquid crystal showing the chiral smectic phase. The amount is 0.1 to 50 parts by weight, preferably 1 to 20 parts by weight, of a liquid crystal exhibiting a nematic phase.

In the present invention, as the chiral smectic liquid crystal shown in Table 1, isotropic phase, smectic A phase (Sm
A) and liquid crystals that sequentially undergo phase transitions in the chiral smectic phase, isotropic phase, cholesteric phase, smectic A phase (SmA), and liquid crystals that sequentially undergo phase transitions in chiral smectic phase, isotropic phase, cholesteric phase Further, it is preferable to use a liquid crystal that sequentially undergoes a phase transition in the chiral smectic phase. Also, for nematic liquid crystal,
It is preferable to use a liquid crystal that causes a phase transition in the smectic phase during the temperature lowering process.

When a device is constructed using these materials, the device is supported by a copper block with a heater embedded, if necessary, in order to keep the liquid crystal compound in a temperature state in which it is in the SmC ^* phase or SmH ^* phase. be able to.

FIG. 1 is a schematic drawing of an example of a cell for explaining the operation of the ferroelectric liquid crystal. 21a and 21b are substrates (glass plates) covered with a transparent electrode made of a thin film such as In ₂ O ₃ , SnO ₂ or ITO (Indium-Tin Oxide), between which the liquid crystal molecular layer 22 is perpendicular to the glass surface. Oriented SmC ^*
Phase or SmH ^* phase liquid crystal is enclosed. A thick line 23 represents a liquid crystal molecule, and the liquid crystal molecule 23 has a dipole moment (P⊥) 24 in a direction orthogonal to the molecule. When a voltage of a certain threshold value or more is applied between the electrodes on the substrates 21a and 21b, the helical structure of the liquid crystal molecules 23 is unraveled,
The orientation of the liquid crystal molecules 23 can be changed so that all the dipole moments (P⊥) 24 are oriented in the electric field direction. The liquid crystal molecule 23 has an elongated shape and exhibits refractive index anisotropy in the major axis direction and the minor axis direction thereof. Therefore, for example, if crossed Nicols polarizers are placed above and below the glass surface, the voltage application polarity is It can be easily understood that the liquid crystal optical modulation element changes its optical characteristics depending on the situation.

The liquid crystal cell preferably used in the liquid crystal element of the present invention can be made sufficiently thin (for example, 10 μm or less). As the liquid crystal layer becomes thinner, the second
As shown in the figure, even when no electric field is applied, the helical structure of the liquid crystal molecules unwinds and adopts a non-helical structure, the dipole moment Pa or Pb of which is upward (34a) or downward (3a).
Take either of the states of 4b). In such cells, the second
As shown in the figure, the electric field Ea or Eb with a certain polarity or more
Is applied by the voltage applying means 31a and 31b, the dipole moment is turned upward 34a or downward 34b in accordance with the electric field vector of the electric field Ea or Eb, and accordingly, the liquid crystal molecules move to the first stable state 33a. Alternatively, it is oriented in either of the second stable states 33b.

As described above, there are two advantages of 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 the liquid crystal molecules has bistability. The second point will be further explained with reference to FIG. 2, for example. When an electric field Ea is applied, the liquid crystal molecules are aligned in the first stable state 33a, but this state is stable even when the electric field is cut off. When an electric field Eb in the opposite direction is applied, the liquid crystal molecules are in the second stable state 33b.
The molecules are oriented to change the direction of the molecules, but they remain in this state even when the electric field is cut off. Further, unless the applied electric field Ea exceeds a certain threshold value, the respective alignment states are also maintained. In order to effectively realize such a high response speed and bistability, it is preferable that the cell is as thin as possible.

As described above, the most problematic factor in forming a device with such a liquid crystal having ferroelectricity is SmC ^*.
It is difficult to form a cell having a high monodomain property in which a layer having a phase or SmH ^* phase is arranged perpendicular to the substrate surface and liquid crystal molecules are aligned substantially parallel to the substrate surface.
It is the main purpose of the present invention to provide a solution to this point.

FIGS. 3A to 3C 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 FIG. 3 (A), the liquid crystal and the polarizer are not shown.

In FIGS. 3A to 3C, an electrode group (for example, a scanning electrode group) including a plurality of electrodes 102 is formed on a substrate 101 formed of a glass plate or a plastic plate in a predetermined pattern by etching or the like. It is formed by. Further, a spacer member 104 having a plurality of side walls 106 and 107 arranged in a stripe shape is formed in a positional relationship in which the electrodes 102 are alternately arranged in parallel.

Further, the electrode 10 except for the spacer member 104 formation portion on the substrate 101
An insulating film 103 is formed so as to cover 2.

The spacer member 104 is, for example, polyvinyl alcohol, polyimide, polyamide imide, polyester imide, polyparaxylylene, polyester, polycarbonate,
Resins such as polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin, etc., or photosensitive polyimide, photosensitive polyamide, cyclized rubber photoresist, phenol novolak It is preferable to select and form a system photoresist or an electron beam photoresist (polymethyl methacrylate, epoxidized-1,4-polybutadiene, etc.).

The insulating film 103 has a function of preventing injection of charges from the electrode 102 into the liquid crystal layer, and for example, silicon monoxide, silicon dioxide,
Aluminum oxide, zirconia, magnesium fluoride,
It can be obtained by using a compound such as cerium oxide, cerium fluoride, silicon nitride, silicon carbide, or boron nitride to form a film by vapor deposition. In addition to them, for example, polyvinyl alcohol, polyimide, polyamide imide, polyester imide, polyparaxylelin, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, urea resin. It can also be formed as a coating film of resin such as acrylic resin. The thickness of the insulating film 103 depends on the charge injection preventing ability of the material and the thickness of the liquid crystal layer, but is usually
It is set in the range of 50Å to 5μ, preferably 500Å to 5000Å. On the other hand, the layer thickness of the liquid crystal layer depends on the ease of orientation peculiar to the liquid crystal material and the response speed required for the element.
Determined by the height of the spacer member 104, usually 0.2μ ~
It is set to 200μ, preferably 0.5μ to 10μ.
The width of the spacer member 104 is usually set in the range of 0.5 μ to 50 μ, preferably 1 μ to 20 μ. If the pitch (space) of the spacer member 104 is too large, it hinders the uniform alignment of the liquid crystal molecules, while if it is too small, the effective area of the liquid crystal optical element is reduced. Therefore, usually 10μ
The pitch is set in the range of ˜2 mm, preferably 50 to 700 μ.

These spacer members 104 are formed in a predetermined pattern 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 is a substrate processed as described above.
Another substrate 110 stacked in parallel with 101 is provided, on which an electrode group consisting of a plurality of electrodes (for example, signal electrodes) 111 and an insulating film 112 are further formed. ing. The plurality of (signal) electrodes 111 and the other plurality of (scanning) electrodes 102 can be wired in a matrix structure. The insulating film 112 on the substrate 110 is for preventing generation of a current flowing through the liquid crystal layer 105 like the above-described insulating film 103, and is formed of the same material as the above-described insulating film 103. According to the present invention, the insulating film 112 of this substrate 101
The plane 113 formed by is subjected to uniaxial orientation treatment, and its orientation direction is substantially parallel to the extension direction of the spacer member 104 on the substrate 101 (that is, the angle between these two directions is θ, preferably 0 ° ≦ θ <15 °) or orthogonal (preferably 80 ° <θ <100 °). At this time, the liquid crystal cell in which the angle θ formed by these two directions is orthogonal is more likely to cause alignment defects than the liquid crystal cell in which the angle θ is parallel. When the rubbing treatment is applied, the liquid crystal cell having the parallel angle θ can form a monodomain having no alignment defect as compared with the liquid crystal cell having the orthogonal angle θ. According to the study by the present inventors, if such a parallel or orthogonal relationship is not satisfied, the alignment of liquid crystal molecules is disturbed at the edge portion of the spacer, and in a cell having a memory effect, switching between bistable states is performed. The phenomenon that is not performed well occurs.
However, as can be seen from the above expression of the range of θ, the deviation up to about 15 ° causes no practical problem. Such uniaxial orientation treatment is accomplished by rubbing the insulating film 112 with velvet, cloth or paper, or by oblique vapor deposition of the insulating film 112, as is well known for TN liquid crystal cells. You can

The uniaxial orientation treatment as described above is basically applied to the substrate.
It is not necessary to perform the step 101, but the step can also be performed on the substrate 101. In this case, after the uniaxial orientation process that is substantially parallel or orthogonal to the extension direction of the spacer member 104, the insulating film 103 is formed by vapor deposition, Alternatively, by performing a uniaxial orientation treatment after forming the insulating film 103, and then selectively removing the orientation treatment effect of the surface 108 formed by the insulating film 103,
It is desirable to selectively impart the alignment treatment effect to the sidewalls 106 and 107 of the space member 104 in order to increase the response speed of the obtained liquid crystal element.

In the liquid crystal element of the present invention, a pair of polarizing means (polarizer 114 and analyzer 115) sandwiching the substrates 101 and 110 on both sides of the pair of parallel substrates 101 and 110 can be used. Polarizer 114
As the analyzer 115, an ordinary polarizing plate, a polarizing film or a polarizing beam splitter can be used. At this time, the polarizing means is in a crossed Nicol state or a parallel Nicol state,
It is possible to arrange.

In the liquid crystal device 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 the periphery thereof is sealed with an epoxy adhesive or a low melting point glass. After that, a ferroelectric liquid crystal is enclosed and heated to an isotropic phase, and then the temperature is precisely controlled and gradually cooled.

In the above, the liquid crystal element of the present invention has been described based on a preferred embodiment thereof. However, within the scope of the present invention, various modifications can be made to the above embodiment,
Easy to understand. For example, if the member described as the spacer member 104 in the above example has a side wall for exerting a necessary wall effect on the liquid crystal, it can also function as a spacer member by contacting both of the pair of parallel substrates. 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 the spacer member 104 may be a deformed striped spacer arranged in a dot shape along a straight line. In addition, the electrodes are not limited to the above-mentioned simple striped matrix electrodes, but may be formed in other shapes, for example, electrode wirings having a 7-segment structure.

Hereinafter, specific manufacturing examples of the optical modulation element of the present invention will be described.

Example 1 A polyimide film having a film thickness of about 1500 Å was formed on one side of a substrate on which a pair of ITO-shaped striped pattern electrodes were formed, and rubbed in one direction (A substrate).

On the other substrate, a polyimide film is formed with a thickness of 2 μm, and the width is 20 μm at intervals of 200 μm by photoetching.
m striped spacers were formed.

As the polyimide, SP-510 manufactured by Toray Industries, Inc. was used, and its N-
A methylpyrrolidone solution was applied by dipping or spinner coating to form a polyimide film.

For etching, use a mixed solution of hydrazine: NaOH = 1: 1 as an etching solution, raise the temperature to 30 ° C., immerse the substrate on which the polyimide film is formed for 3 minutes, and immerse the substrate on which the polyimide film is formed for 3 minutes. Then, etching was performed (B substrate).

The pair of electrode substrates prepared in the above steps are assembled into a liquid crystal cell (cell thickness: 2 μm) by aligning the stripe-shaped spacer direction and the rubbing direction substantially parallel to each other, and the composition in the isotropic phase is placed in the cell. A was injected and the cell temperature was gradually cooled at a rate of 5 ° C./hour to prepare a non-helical chiral smectic liquid crystal cell.

After injecting the following composition A having an isotropic phase into the liquid crystal cell,
The cell temperature was gradually cooled at a rate of 5 ° C./hour to prepare an SmC ^* liquid crystal cell. Observation of this SmC ^* liquid crystal cell with a polarization microscope revealed that a non-helical monodomain without alignment defects was formed.

Composition A DOBAMBC 100 parts by weight 4-hexyloxy-4'-cyanobiphenyl 5 parts by weight Examples 2-10 Instead of the composition A used in the above Example 1, the following composition B was used.
(Example 2), C (Example 3), D (Example 4), E
(Example 5), F (Example 6), G (Example 7), H
A liquid crystal cell was prepared in the same manner as in Example 1 except that (Example 8), I (Example 9) and J (Example 10) were used, and each SmC ^* liquid crystal cell was subjected to a polarization microscope. As a result, the form of the non-helical monodomain in which orientation defects did not occur was confirmed.

Composition B DOBAMBC 100 parts by weight trans, trans-4'-propyldicyclohexyl-4-carbonitrile 1 part by weight Composition C 4- (2'-methylbutyl) phenyl-4'-octyloxybiphenyl-4-carboxylate 100 Parts by weight trans, trans-4′-propyldicyclohexyl-4-carbonitrile 1 part by weight Composition D DOBAMBC 100 parts by weight 5-n-hexyl-2- (4-hexyloxyphenyl) pyrimidine 5 parts by weight Composition E 4 -Pentylphenyl-4- (4 "-methylhexyl)
Biphenyl-4'-carboxylate 100 parts by weight 5-n-hexyl-2- (4-hexyloxyphenyl) pyrimidine 5 parts by weight Composition F 4-hexyloxyphenyl-4- (2 "-methylbutyl) biphenyl- 4'-carboxylate 100 parts by weight 5-n-hexyl-2- (4-hexyloxyphenyl) pyrimidine 5 parts by weight Composition G DOBAMBC 100 parts by weight N- (4-ethoxybenzylidene) -4-n-hexylaniline 5 parts by weight Composition H DOBAMBC 100 parts by weight N-n-pentyl-4'-methoxyazobenzene 5 parts by weight Composition I DOBAMBC 100 parts by weight 4-n-hexyl-4'-n-butoxyazobenzene 5
Parts by weight Composition J DOBAMBC 100 parts by weight 4-n-butylbenzoic acid -4'-n-hexyloxyphenyl ester 5 parts by weight Example 11 Substrate on which a striped pattern electrode composed of a pair of ITO was formed On one side, a polyimide film was formed with a film thickness of about 1500 Å and rubbed in one direction. On the other substrate, a polyimide film having a thickness of 2 μm was formed, and a stripe spacer having a width of 20 μm was formed with a pitch of 200 μm by photoetching, and a rubbing treatment was performed in parallel with the direction of the stripe spacer.

As the polyimide, SP-510 manufactured by Toray Industries, Inc. was used, and its N-
A methylpyrrolidone solution 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 liquid crystal cell (cell thickness: 2 μm) was formed by aligning the pair of electrode substrates produced in the above steps with the direction of the stripe-shaped spacers 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 gradually cooled at a rate of 5 ° C./hour,
When observed under a microscope, non-helical monodomes having no alignment defect were formed.

Example 12 A liquid crystal cell was constructed in the same manner as in Example 1 except that a pair of substrates was combined so that the rubbing treatment direction and the stripe spacer extension direction were orthogonal to each other.

When this liquid crystal cell was observed with a polarization microscope, some alignment defects were observed near the edge of the stripe spacer.

Example 13 A polyimide film having a thickness of about 1500 Å was formed on one side of a substrate on which a pair of ITO-shaped striped pattern electrodes were formed, and rubbed in one direction (A substrate).

On the other substrate, a polyimide film is formed with a thickness of 2 μm, and the width is 20 μm at intervals of 200 μm by photoetching.
m striped spacers were formed.

As the polyimide, SP-510 manufactured by Toray Industries, Inc. was used, and its N-
A methylpyrrolidone solution was applied by dipping or spinner coating to form a polyimide film.

The 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 having the polyimide film formed therein for 3 minutes. Then, the same polyimide film as that described above was formed over the entire surface of the substrate on which the stripe spacers were formed. However, the film thickness of the polyimide at this time was 1000Å. Then, the surface of this polyimide film was rubbed in a direction parallel to the extension direction of the spacers on the stripe. (B ″ substrate) A cell set (cell thickness; 2 μm) is formed so that the rubbing directions of the pair of electrode substrates prepared in the above process are parallel to each other.
Then, the composition A having an isotropic phase was injected into this cell and slowly cooled to prepare a chiral smectic liquid crystal device having a non-helical structure.

It was found that this liquid crystal cell formed a stable monodomain that did not cause alignment defects in SmC ^* even after standing for several days, as compared with the liquid crystal cells used in the other examples.

Further, when a pulse signal of 1 mse at 20 V was applied to this liquid crystal element to drive it, it was found that the contrast between the bright state and the dark state was large as compared with the case of Example 1.

Comparative Example 1 When the liquid crystal cell of Example 1 was assembled, a pair of electrode substrates were superposed except that the angle θ formed by the stripe spacer direction and the rubbing direction was 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, black streak states due to innumerable alignment defects were observed near the edges of the stripe spacer, and the black streak covered the electrode formation part. It was found that even if two kinds of electrode signals having different polarities were applied between the pair of electrodes, no bistability was exhibited in the portion where the black streaks were formed.

Comparative Example 2 The same striped spacer used when the liquid crystal cell of Example 13 was formed and the electrode substrate provided with the polyimide film were prepared, and the direction of extension of the striped spacer was measured on the surface of the polyimide film. A rubbing treatment was applied in the direction of an angle of 25 °.

Next, the same one-sided electrode substrate used in Example 13 was prepared and rubbed in one direction.

The two electrode substrates were stacked so that the rubbing directions were parallel to each other, and then the cells were assembled, and then a non-helical SmC ^* liquid crystal cell was prepared by the same procedure as in Example 1, and then the liquid crystal was prepared. When the cell was observed in the same manner as in Example 1, similarly to Comparative Example 1, fatal alignment defects were observed in the display device. An electric signal was applied between the pair of electrodes as described above, but no bistability was shown.

Next, in order to clarify the effect of the sidewall member of the present invention on the memory property of the bistability of the device, the following two liquid crystal devices as comparative examples were produced.

Comparative Example 3 A cell having no side wall was prepared by the following method. As described in the examples, ITO stripe electrodes were arranged on a pair of substrates, and a polyimide film was formed on one side to a thickness of 1500 Å, and rubbed in one direction. (A 'substrate). A polyimide film having a film thickness of 2 μm was formed on the other substrate, and a spacer was formed by etching, leaving only the peripheral edge portion other than the liquid crystal injection port (B ′ substrate).

The pair of electrode substrates created in the above steps were assembled into cells in the same manner as the cells of Example 2.

After injecting the isotropic phase composition A used in Example 1 into this liquid crystal cell, the temperature of the cell was gradually cooled at a rate of 5 ° C./hour to prepare a chiral smectic liquid crystal element having a non-helical structure.

Comparative Example 4 A liquid crystal element having the composition A was prepared in the same manner as in Example 8 except that the stripe-shaped spacers were left only at the peripheral edges of the cell.

In order to measure the degree of bistability in the cells under the chiral smectic state of Comparative Example 3 and Example 1 of the present invention, and Comparative Example 4 and Example 13 of the present invention, the following method is used. evaluated.

Set the cell under the Sm ^* state on a polarizing microscope (BH-2: Olympus Optical Co., Ltd.) with 100x magnification, connect the electrode of the A electrode plate in the cell to the ground, and connect the B electrode. Positive polarity pulse (voltage value = 10 V; pulse width = 1 msec) or negative polarity pulse (voltage value = -10 V; pulse width = 1 mse) on the plate electrode
The amount of transmitted light after applying c) is measured with a photomultiplier (Hamamatsu Photonics KK; product name: Photomaru tube R761), and the positive pulse with respect to the output voltage B ₂ (mV) when the negative pulse is applied. Output voltage B when applied
The ratio B ₁ / B ₂ = B ₀ of ₁ (mV) was obtained.

Further, the ratio A ₁ / A ₂ = A ₀ of the photomultiplier output voltage A ₁ (mV) after the positive pulse is applied to the photomultiplier output voltage A ₂ (mV) after the negative pulse is applied, Ratio A ₀ after pulse application to ratio B ₀ during pulse application
The degree of bistability was measured by determining the ratio A ₀ / B ₀ of.

The larger the ratio A ₀ / B _{0, the} better the degree of bistability, that is, the better the memory property of the device. At this time, the crossed Nicols of the above-mentioned polarization microscope were set so that the darkest state would occur when a negative pulse was applied.

The results of the above evaluation measurements are shown in Table (I).

As described above, the result that the parameter indicating the degree of bistability becomes large was obtained.

〔The invention's effect〕

As described above, according to the present invention, a structural member (preferably also a spacer) having a stripe-shaped side wall is formed on one electrode substrate of a pair of electrode substrates, and the other substrate is uniaxially oriented (for example, Rubbing) to regulate the treatment direction to a direction substantially parallel or orthogonal to the above structural member, and use a liquid crystal composition containing at least a liquid crystal exhibiting a chiral smectic phase and a liquid crystal exhibiting at least a nematic phase as the liquid crystal. This makes it possible to eliminate defects in the spacer edge even in a memory state where defects are likely to appear.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a liquid crystal element using a chiral smectic liquid crystal. FIG. 2 is a perspective view schematically showing bistability of the liquid crystal element. Figure 3 (A)
Is a perspective view of the 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.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Yoshinaga 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP 59-201021 (JP, A) JPB 63 -34453 (JP, B1) Mol. Cryst. Lig. Crys t. vol. 89, pp. 328-329 (1982)

Claims (4)

[Claims] 1. A liquid crystal device in which liquid crystal is arranged between a pair of substrates, wherein one of the pair of substrates has a height of 0.2 to 200 μm, a width of 0.5 to 50 μm, and an interval of 10 μm to 2 mm. A plurality of parallel structural members having sidewalls arranged in a stripe shape are provided, and at least one of the pair of substrates is subjected to uniaxial alignment treatment. The angle θ formed by the extension directions of the plurality of structural members is 0 ° ≦ θ ≦ 15 ° or 80 ° ≦ θ ≦ 100 °, and the first liquid crystal of the first liquid crystal that produces a chiral smectic phase is formed between the substrates. Chiral smectic liquid crystals containing at least one kind and at least one kind of second liquid crystal which produces a nematic phase are sandwiched at intervals such that the helical structure in the chiral smectic phase disappears, and The iral smectic liquid crystal undergoes a phase transition to a chiral smectic phase by lowering the temperature from a phase higher than the smectic phase through a nematic phase, and is aligned in one of two different alignment states in the absence of an electric field, The chiral smectic liquid crystal is perpendicular to the substrate surface,
A chiral smectic liquid crystal device comprising means for applying an electric field of sufficient intensity to cause transition from one of the two different alignment states to another state. 2. The chiral smectic liquid crystal device according to claim 1, wherein the height of the side wall is 0.5 to 10 μm. 3. The chiral smectic liquid crystal device according to claim 1, wherein the width of the side wall is 0.5 to 10 μm. 4. The chiral smectic liquid crystal device according to claim 1, wherein the distance between the side walls is 0.5 to 10 μm.