JP4053530B2 - Zero-plane anchoring liquid crystal alignment method and liquid crystal device - Google Patents

Description

  The present invention relates to a zero-plane anchoring liquid crystal alignment method and a liquid crystal device thereof. Here, when referring to “zero-plane anchoring”, “zero-anchoring” means “no anchoring and no alignment forcing”, so “zero-plane anchoring” is in-plane. It means that there is no orientation forcing. Anchoring (orientation force) includes the force that defines the direction in the plane (within the horizontal plane where the axis of the horizontally arranged molecule is located) and the angle when there is an out-of-plane (horizontal, vertical, or angle) angle. In this case, the horizontal or oblique orientation is forced, but the orientation forcing force in the in-plane direction is zero. However, in the case of vertical alignment, it may be considered zero.

  FIG. 8 is a schematic diagram showing liquid crystal alignment control by a conventional solid alignment film.

  In FIG. 8, 1 is a solid alignment layer, 2 is a solid alignment film, and 3 is a nematic phase liquid crystal [LC (N)].

  Conventionally, most of the display principles of liquid crystal displays (TN (Twisted Nematic) type liquid crystal, FLC (ferroelectric liquid crystal), IPS (In-Plane Switching) type, optical alignment type, etc.)) Is used in advance. However, with the exception of FLC, these display modes have no memory in principle. In addition, there is a drive threshold except for a special display mode such as V-shape. On the other hand, if the liquid crystal can be held at a free interface, the anisotropic axis of the liquid crystal is inherently degenerate in all directions, so the direction of the anisotropic axis in the external field (electric field, magnetic field, electromagnetic field, etc.) It should be possible to control freely and memorize the anisotropic axis in any orientation. However, if this is to be achieved, the alignment field is always constrained at the boundary of the solid cell surface necessary to fix the liquid crystal rich in fluidity, and the symmetry is broken.

  Thus, since the alignment field of the liquid crystal must be defined at the container interface of the liquid crystal display, various alignment techniques such as horizontal, oblique, and vertical have been developed. In particular, in the case of oblique and horizontal alignment, a method of forcing a horizontal uniaxial alignment property from the beginning at the interface is used even though there is a degree of alignment freedom in the plane. In general, an appropriate polymer thin film is applied onto a substrate, and a rubbing method of rubbing this with a cloth or the like, molecules having properties such as photo-orientation are fixed to the substrate surface, and then the substrate is used with light. A technique for imparting axiality to the surface is used.

  The main reason for this is that it is difficult to give complete randomness to the solid surface other than the requirement from the principle of the display mode such as FLC and TN, or that the liquid crystal can be uniformly aligned even without an electric field. In other words, it is difficult to perform horizontal alignment without breaking the in-plane symmetry.

  On the other hand, there is an attempt to give the surface of solid / amorphous state randomness with sufficiently short wavelength to extinguish the alignment axis of the liquid crystal, but on the solid surface, the micro motion of liquid crystal molecules is essentially constrained. Therefore, in order to rotate the anisotropic axis by an external field, a tremendous force and relaxation time are required compared with the alignment elastic force of the liquid crystal.

  As a method for macroscopic alignment control without losing the micro mobility of liquid crystal molecules while avoiding the above circumstances, there is a method using an interface between a liquid and a liquid crystal instead of a solid interface. However, a liquid crystal material used for a liquid crystal display or the like is rich in fluidity, so that a cell sandwiching the liquid crystal material is necessary for use as a display device, and contact with a solid surface is required. Although there is an attempt to apply a sufficiently large amount of low molecular weight material to the substrate in advance, an apparently short time (diffusion time depends on the material and temperature) exists between the liquid crystal material into which the fluid is injected later. Of course, this liquid dissolves in the liquid crystal material and diffuses (Patent Document 1 below).

  On the other hand, by mixing a substance insoluble in the liquid crystal, a liquid-liquid crystal interface can be formed in the sample by a phase separation phenomenon. However, as seen in the water-oil mixed system, the interface formed by the substances that do not dissolve in each other becomes spherical due to the presence of a large surface tension, so that it is extremely difficult to use as an interface of a liquid crystal display element. is there.

  The inventor of the present application prepares an obliquely deposited SiO film on one side and a rubbed PVA film on one side by modeling the affinity for the substrate in the following Non-Patent Documents 1 and 2, and the liquid crystal is simply carbonized. Using a two-component system in which hydrogen is mixed, a liquid-liquid crystal interface in a completely wet state intended by the present invention is realized in a two-phase coexistence state of isotropic and nematic phases. This resulted in an axisless interface that forced the alignment in horizontal (oblique) orientation.

However, in simple liquid mixing, the complete wetting state is limited to a narrow temperature range between 0.6 ° C. where a coexisting phase exists. This is because in the dilution phase diagram created by a mixed system with a simple liquid, the compatibility difference between the mixed substance and the liquid crystal substance is lowered to expand the coexistence phase region. This is because the interfacial tension is increased, and the liquid-liquid crystal interface is not completely wetted and is partially wetted to form droplets. Therefore, in a system having such a diluted phase diagram, it is impossible to realize a liquid (liquid crystal) -liquid crystal interface in a completely wet state in a wide temperature range. Of course, there is no patent document or published document regarding the applicability as a liquid crystal display device using such a complete wetting interface and its characteristics (360-degree rotational symmetry, memory property, thresholdlessness, etc.).
JP 2003-98553 A Mol. Cryst. Liq. Cryst. 99, pp. 39-52 (1983) Mol. Cryst. Liq. Cryst. 107, pp. 311-331 (1984)

  In view of the above circumstances, the present invention provides a zero-plane anchoring liquid crystal alignment method capable of realizing a liquid-liquid crystal interface, which is realized only in a narrow temperature range, in a sufficiently wide temperature range required by a normal display element. And it aims at providing the liquid crystal device.

In order to achieve the above object, the present invention provides
[1] In the zero-plane anchoring liquid crystal alignment method, by adding a polymer to a liquid crystal sample, liquid-phase separation with the addition of the liquid-polymer is stably induced, and the liquid-polymer is added. Using the liquid crystal interface, the liquid crystal to which the polymer is added has no in- plane alignment force and is aligned in a predetermined horizontal, vertical, or oblique direction, and the liquid-liquid crystal to which the polymer is added In order to stabilize the interface, a surfactant is mixed .

[ 2 ] The zero-plane anchoring liquid crystal alignment method according to [1] above, wherein the liquid crystal interface to which the liquid-polymer is added and the geometric irregularities of the substrate surface are combined.

[ 3 ] The zero-plane anchoring liquid crystal alignment method according to [1] above, wherein the liquid crystal interface to which the liquid-polymer is added is used in a process for forming an alignment film.

[ 4 ] A liquid crystal device, which is produced by the zero-plane anchoring liquid crystal alignment method described in any one of [1] to [ 3 ].

[ 5 ] A liquid crystal optical switching device, wherein the liquid crystal device according to the above [ 4 ] is used to perform liquid crystal switching by means of liquid crystal alignment rotation by a change in external field.

[ 6 ] The liquid crystal optical switching device according to [ 5 ], wherein the external field is an electric field or a magnetic field.

[ 7 ] The liquid crystal optical switching device according to [ 5 ], wherein the external field is light irradiation.

  According to the present invention, the liquid-liquid crystal interface, which is realized only in a narrow temperature range, can be realized in a sufficiently wide temperature range required by a normal display element.

In the zero-plane anchoring liquid crystal alignment method, by adding a polymer to a liquid crystal sample, the liquid-liquid crystal phase separation to which the polymer is added is stably induced, and the liquid-liquid crystal interface to which the polymer is added The liquid crystal to which the polymer is added is oriented in a predetermined horizontal, vertical, or oblique direction without any forcing force in the plane, and the liquid-liquid crystal interface to which the polymer is added is stabilized. In order to make it into a surface, a surfactant is mixed . Therefore, a liquid crystal interface to which a completely wetted liquid-polymer is added, which is realized only in a narrow temperature range, can be realized in a sufficiently wide temperature range required by a normal display element. Furthermore, the liquid-liquid crystal interface in a completely wet state can be stabilized by adding a surfactant.

  Hereinafter, embodiments of the present invention will be described in detail.

  (1) First, a mixed system that realizes a liquid-liquid crystal interface in a completely wet state in a wide temperature range will be described.

  FIG. 1 is a phase diagram of a polymer-liquid crystal mixed system optimized for various liquid-liquid crystal interfaces according to the present invention, and FIG. 1A is a phase diagram of a simple liquid-liquid crystal mixed system. FIG. 1B is a phase diagram of a polymer-liquid crystal mixed system, and FIG. 1C is a phase diagram of a polymer-liquid crystal mixed system optimized for a completely wet liquid-liquid crystal interface. In these figures, the horizontal axis indicates the concentration, and the vertical axis indicates the temperature. In the figure, 11 is a simple liquid region (I), and light gray region 12 is a liquid-liquid crystal coexistence region (I + N), which is black. A region 13 indicates a liquid crystal region (N).

  First, another substance is mixed with the liquid crystal material, and another phase (liquid phase or liquid crystal phase) in a liquid or liquid crystal state is generated by phase separation. The temperature range of the coexistence region 12 where the liquid crystal phase and this phase coexist can be controlled by the compatibility of the substance to be mixed and the liquid crystal material. In general, when a simple liquid is mixed with liquid crystal, a dilution phase diagram as shown in FIG. 1 (a) is obtained, and the liquid-liquid crystal coexistence region 12 shown in light gray expands as the liquid crystal phase transition temperature decreases. .

  However, in the case of the phase diagram shown in FIG. 1 (a), the liquid-liquid crystal interface in the fully wet state is realized when the concentration difference between the two phases separated is rather small, that is, in the region where the concentration of the mixed substance is low. Limited to. However, in this region, phase separation cannot be realized in a sufficiently wide temperature region. In other words, it is essentially impossible to achieve both the realization state of the completely wet state and the phase separation conditions in a wide temperature range.

  On the other hand, a general mixed system of a polymer and a liquid crystal substance has an upper limit compatible type phase separation curve often seen in a polymer solution as shown in FIG. 1 (b) [lower part of FIG. 1 (b)]. In general, a conical coexistence region 12] and a diluted phase diagram of the liquid-liquid crystal phase transition shown in FIG. The appearance of the coexistence region of the upper limit compatible type is a phenomenon that occurs due to competition between the compatibility between the polymer and the liquid crystal and the entropy in the polymer solution, and is extremely common in polymer solutions. In the case where the solvent is a liquid crystal, the liquid-liquid crystal transition is diluted by mixing of the polymer in addition to the liquid crystal region, so that a coexistence region appears as a strong primary transition. Therefore, the same type of phase separation curve as that in FIG. 1A appears in the high liquid crystal concentration region. Of particular importance is that near the critical concentration (top of phase diagram) of the upper limit compatible phase separation curve, the free energy difference between the two phases becomes small, the critical wetting state occurs at a very wide temperature and concentration, and the phase separation interface is It is to be completely wet spontaneously. In the present invention, by optimizing the compatibility between the polymer segment (monomer) and the liquid crystal substance, or the polymer molecular weight, the phase separation curve of the liquid-liquid crystal phase transition and the phase diagram of the upper limit compatibility type are antagonized. Thus, a liquid-liquid crystal interface in a completely wet state can be formed at a wide temperature and concentration.

  (2) Next, stabilization of the completely wetted liquid-liquid crystal interface by addition of a surfactant will be described.

  In the present invention, a liquid-liquid crystal in a completely wet state is further synthesized by synthesizing a kind of surfactant having both properties of the substance to be mixed and the original liquid crystal molecule in one molecule and adding it to the target mixed system. We propose to stabilize the interface over a wide temperature range. If the surfactant can sufficiently activate the liquid-liquid crystal interface, the range of selection of the substance to be mixed and the temperature / concentration region will be greatly widened, which is a great practical advantage. For example, in the case of a polymer-liquid crystal mixed system, a polymer-liquid crystal polymer diblock copolymer can be used.

  Here, it should be noted that:

  In addition to the liquid-liquid crystal interface, it is also necessary to control the glass-liquid interface. This (1) gives the solid substrate surface a stronger affinity for the liquid phase phase-separated from the liquid crystal substance. (2) On the contrary, a non-affinity which dislikes a liquid crystal substance is given like a vertical alignment substrate coated with soap molecules. Since the surface on which soap molecules are applied dislikes the liquid crystal material, it creates a strong surface tension and tries to keep the liquid crystal material away.

(3) Method of manufacturing a liquid crystal device using a liquid-liquid crystal horizontal alignment surface in a completely wet state For the alignment direction of liquid crystal molecules at the liquid-liquid crystal interface, a combination of liquid crystal, a mixture, and a surfactant is selected. , The horizontal / vertical / diagonal orientation can be uniquely controlled. Here, the liquid-liquid crystal interface in a completely wet state that realizes the horizontal direction is formed on two upper and lower substrates, and the liquid crystal phase is sandwiched between the liquid phases separated from each other, or the opposite substrate is vertically aligned. A display cell is produced. In order to realize a planar interface even at the second interface, ie, the solid substrate-liquid interface, the substrate is processed in advance by one of the following two methods. (A) The solid substrate surface has a stronger affinity for the mixed substance. (B) The solid substrate surface gives non-affinity that dislikes the liquid crystal substance.

  FIG. 2 is a schematic view of a liquid crystal device composed of a completely wetted liquid-liquid crystal interface according to the present invention.

  In this figure, 21 is a cell substrate, 22 is a liquid phase region in a completely wet state, 23 is a liquid crystal nematic phase region, and the liquid phase region 22 in a completely wet state is layered between the cell substrate 21 and the nematic phase region 23. Formed and forces the horizontal orientation of the nematic phase region 23.

(4) Advantages and features of liquid crystal optical switching devices using liquid-liquid crystal horizontal alignment surface in a completely wet state At the liquid-liquid crystal horizontal alignment interface in the realized liquid crystal display device, the energy related to liquid crystal alignment is Since the direction is degenerate, the anisotropic axis is equivalent in any direction. As a result, it is possible to manufacture a liquid crystal display that can freely rotate 360 degrees by an electric field, a magnetic field, etc., has memory characteristics in the orientation direction even when the field is cut off, and has no threshold in the driving external field in principle. Become.

  The feature of the liquid crystal device of the present invention is that the interface holding the liquid crystal phase in the display cell is not a solid interface as in the prior art, but an interface of liquid or liquid crystal phase. Similar to the present invention, the problem of the conventional alignment technique for creating a rotation-free interface is that a solid surface prepared in advance is used for the glass surface of the display cell. Since the solid surface extremely restricts the movement of liquid crystal molecules by adsorption or the like, it has properties that are physically very different from the alignment interface of the present invention. At the liquid-liquid crystal interface, diffusion between the liquid crystal molecule interfaces is extremely free, and the interface seen from the microscopic level has only a difference between a liquid crystal state and a liquid (another liquid crystal) state. This property is an innovative point of the present invention.

  In the zero-plane anchoring liquid crystal alignment method of the present invention, the completely wet liquid-liquid crystal interface may be combined with the geometric irregularities on the substrate surface.

  Furthermore, in the zero-plane anchoring liquid crystal alignment method of the present invention, the completely wet liquid-liquid crystal interface may be used in the alignment film manufacturing process.

  In order to produce a liquid-liquid crystal interface in a completely wet state, first, another substance is mixed with the liquid crystal material in order to create a coexistence state between the liquid crystal phase and the liquid or another liquid crystal phase. Here, a material obtained by adding a polystyrene molecule having a molecular weight of 2000 to a liquid crystal molecule PAA (paraazoxyanisole) having a nematic phase to a weight concentration of 2% was used. The shape of the phase diagram is determined by the compatibility of the liquid crystal material and the mixed material. When a polymer is used in a mixture, the molecular weight is an indispensable parameter for determining the phase diagram, and at the same time, the glass transition temperature is an important factor in optimizing the mixing system. The example used here is one example that satisfies the condition that a completely wet liquid-liquid interface exists stably over a wide temperature range. In addition, the alignment direction (horizontal, vertical, diagonal) of the liquid crystal at the obtained interface also varies depending on the properties of both substances, temperature and concentration. In the materials exemplified here, the liquid crystal alignment is horizontal alignment at the liquid-liquid crystal interface in almost all temperature and concentration ranges.

  Further, in this example, a small amount (<0.5%) of a surfactant was added to stabilize the coexisting two-phase interface and realize a completely wet state. This surfactant has a polystyrene chain and side chain type polymer that has a portion having affinity for both polystyrene molecules and liquid crystal molecules in one molecule so that soap molecules activate the interface between water and oil. A block copolymer obtained by copolymerizing liquid crystal was used. In addition, as the interface that strongly repels the liquid crystal molecules so that the liquid phase phase-separated from the liquid crystal phase completely wets the glass interface, a glass plate coated and sintered with a liquid crystal molecule vertical alignment agent is prepared up and down. It was. As a result, although the thickness of the liquid phase depends on the temperature, the intended completely wet liquid-liquid crystal interface was obtained in an extremely wide temperature range of 10 ° C. or more below the phase transition point. The temperature range of this mixed system is determined by the crystallization temperature of PAA and the glass transition temperature of polystyrene-diblock liquid crystal, and is not an essentially determined temperature range as in the case of a simple liquid, By optimizing the material, it can be expected that a system with a wider temperature range can be found in the room temperature region.

Was subjected to treatment with prior mentioned vertical alignment agent, sandwiched sample between two glass substrates of a thickness (substrate distance) 50 [mu] m, nematic phase - FIG polarization microscope photograph of coexistence region when the temperature of the liquid phase coexisting 3 shows. According to FIG. 3, the nematic phase apparently exists on the entire surface of the sample, and a unique texture indicating the horizontal orientation of the nematic phase, called a schlieren pattern, is confirmed. In the cooling process from the isotropic phase, it is confirmed that the isotropic phase droplets are absorbed and disappeared by the interface, and the liquid crystal molecules are used in a horizontal direction despite the use of a substrate that originally enforces vertical alignment. The emergence of orientation proves that the liquid phase, which is completely wetted as intended, is formed in layers between the nematic phase and the cell substrate, forcing the horizontal orientation.

  Features of a liquid crystal optical switching device composed of a fully wetted liquid-liquid crystal alignment interface (1. Alignment can be rotated in any direction by an external field, 2. Memory property, 3. Threshold zero) Will be explained. When an electric field is used for the external field, four electrodes are arranged every 90 degrees, and different voltages (generally, low-frequency alternating current with a uniform phase) are applied between the two electrodes facing each other. By changing the ratio of two orthogonal electric fields, the direction of the combined electric field can be directed to an arbitrary angle. Here, a method of applying a magnetic field by changing the direction of the magnetic field and the direction of the sample with a rotating stage was used.

  4A and 4B are typical switching polarization micrographs. FIG. 4A is a polarization micrograph of a sample after applying a magnetic field (1.2 kG), and FIG. 4B is a 45 ° sample rotated after the magnetic field is turned off. It is the polarization micrograph which was taken and taken. Here, the polarization of the illumination light is aligned with the direction of the magnetic field (that is, the polarization direction of the polarization microscope is matched with the direction of the magnetic field), and the analyzer is in crossed Nicols, so FIG. Then, since the anisotropic axes of liquid crystal molecules are aligned in the magnetic field direction, the light does not pass through and becomes black. From FIG. 4A, it can be seen that there is no alignment defect and the alignment state is uniform. In this state, the magnetic field is turned off and only the sample is rotated 45 degrees as shown in FIG. Even when the magnetic field is cut off, the alignment of the liquid crystal is memorized, so that light is transmitted and brightened due to the anisotropy of the liquid crystal. The entire sample transmits light uniformly, and it can be confirmed that uniform orientation switching has been performed.

  In FIG. 5, after applying an initial magnetic field at an arbitrary position and aligning the alignment direction, it is rotated 45 degrees so that the transmitted light intensity becomes maximum, and transmission after applying a magnetic field at t = 0. It is a figure which shows the result of having measured the time change of light intensity.

  When the strength of the applied magnetic field is changed, the relaxation time changes from 400 msec (magnetic field strength 1.2 kG) to 10 sec (magnetic field strength 300 G), but if a magnetic field is applied for a sufficiently long time, the transmitted light intensity is increased with all the magnetic field strengths. Decreases to the same size, and it can be seen that the alignment direction of the liquid crystal is completely rotated. This result proves that this optical switching device has no threshold.

  Similarly, an example in which the temporal change of the light intensity after cutting the magnetic field is measured is indicated by a black line in the figure. When the orientation direction deviates from the magnetic field direction, the light intensity increases. The increase in transmitted light intensity within 40 seconds after cutting the magnetic field is within several percent, and good memory performance is ensured.

  On the other hand, the measurement shows that the horizontal alignment of the liquid-liquid crystal interface in the completely wet state has 360-degree rotational symmetry.

The photograph in FIG. 6 shows a 1.2 kG magnetic field in each of seven directions θ = 0, 15, 30, 45, 60, 75, and 90 degrees with respect to a fixed direction θ = 0 degrees with the sample cell. Is a photograph taken by cutting the magnetic field and rotating the sample again in the direction of θ = 0 degrees.

  The transmitted light intensity is minimum at 0 ° and 90 °, and maximum at 45 °, and it can be clearly seen that uniform horizontal orientation is realized and stored in any direction of the sample cell.

Further, after applying the initial magnetic field similarly seven directions, rotated from theta = 0 degrees to 90 degrees, showing the results of measurement by the photodiode changes in transmitted light intensity in FIG.

  It can be seen that the anisotropic axis rotates as the sample rotates, and the transmitted light intensity changes ideally due to birefringence. There is almost no change in orientation within the measurement time, and the memory performance is clear from here. It can also be seen that the angle dependence of the transmitted light intensity with respect to the direction of the initial magnetic field is completely uniform, and an orientation of 360 degrees can be selected completely symmetrically.

  In the above embodiment, an electric field or a magnetic field is used as the external field, but light irradiation may be used. In that case, in order to give the alignment rotation torque by light irradiation, for example, liquid crystal molecules having an azo group can be mixed. When liquid crystal molecules having an azo group are irradiated with polarized ultraviolet light, only the molecules in the plane of polarization of the light having the transition moment of the azo group are excited by trans-cis photoisomerization. Since liquid crystal molecules do not like to be excited, an attempt is made to create an orientation distribution that removes the transition moment from the plane of polarization as much as possible. That is, the liquid crystal molecules are apparently subjected to rotational torque by light.

  Further, the present invention is not limited to the above-described embodiments, and various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

  The zero-plane anchoring liquid crystal alignment method and the liquid crystal device of the present invention are suitable as a liquid crystal optical switching device that can rotate and rotate 360 degrees in a horizontal plane by an external electric field and magnetic field and has a memory property but no switching threshold.

FIG. 2 is a phase diagram of a polymer-liquid crystal mixed system optimized for various liquid-liquid crystal interfaces according to the present invention. It is a schematic diagram of the liquid crystal device comprised by the liquid-liquid-crystal interface of the completely wet state which shows the Example of this invention. It is a figure which shows the polarizing microscope photograph (in the coexistence area | region) after lowering | hanging temperature from the liquid phase which shows the Example of this invention, and making it transfer to a liquid crystal phase. It is a figure which shows the typical switching polarized light micrograph which shows the Example of this invention. It is a figure which shows the light intensity time change (including the time change at the time of a magnetic field OFF) of the external field response which shows the Example of this invention. It is a photograph which shows the magnetic field application direction and transmitted-light intensity | strength (polarized light microscope photograph) which show the Example of this invention. It is a figure which shows the transmitted light intensity change by the sample rotation which shows the Example of this invention, and its initial magnetic field application direction dependence. It is a schematic diagram which shows liquid crystal alignment control by the conventional solid alignment film.

Explanation of symbols

11 Simple liquid region (I)
12 Liquid-liquid crystal coexistence region (I + N)
13 Liquid crystal region (N)
21 Cell substrate 22 Fully wetted liquid phase region 23 Liquid crystal nematic phase region

Claims (7)

By adding a polymer to the liquid crystal sample, liquid-phase separation with liquid-polymer added is stably induced, and the liquid-crystal interface with the liquid-polymer added is used to add the polymer. In order to stabilize the liquid crystal interface to which the liquid and the polymer are added, the surfactant is mixed with the liquid crystal so that the liquid crystal is aligned in a predetermined horizontal / vertical / diagonal direction without in- plane alignment force. A zero-plane anchoring liquid crystal alignment method characterized by:   2. The zero-plane anchoring liquid crystal alignment method according to claim 1, wherein the liquid crystal interface to which the liquid-polymer is added and the geometric irregularities of the substrate surface are combined.   2. The zero-plane anchoring liquid crystal alignment method according to claim 1, wherein the liquid-crystal interface to which the liquid-polymer is added is used in a process for producing an alignment film. The liquid crystal device produced by the zero surface anchoring liquid crystal aligning method as described in any one of Claims 1-3 . 5. A liquid crystal optical switching device using the liquid crystal device according to claim 4 , wherein the liquid crystal is switched by a liquid crystal alignment rotating means by a change in external field. 6. The liquid crystal optical switching device according to claim 5 , wherein the external field is an electric field or a magnetic field. 6. The liquid crystal optical switching device according to claim 5 , wherein the external field is light irradiation.