JPS60119525A - Method for controlling orientation of liquid crystal - Google Patents

Abstract

PURPOSE:To improve monodomain formability and to exhibit substantially the characteristic of the liquid crystal by decreasing the temp. of the high temp. phase generated by moving a heating means from one end toward the other end of a cell structural body contg. a uniaxial anisotrophic phase compd. thereby forming the uniaxial anisotropic phase thereof. CONSTITUTION:An electrode group consisting of transparent electrodes 102, 102' is provided on the base plates 101, 101' of a liquid crystal cell 100 having the construction in which a pair of the base plates 101 and 101' are held at a prescribed space by a spacer 103 and are held by an adhesive agent 106. A monodomain of SmA is formed if a heating element 107 is moved in an arrow 108 direction from one end toward the other end of the cell 100 in which a ferrodielectric liquid crystal (for example, DOBAMBC) is sealed then shifting the element 107 to an isotropic phase and when the process for decreasing the temp. is generated in succession thereto. The uniform monodomain is thus formed and the characteristic of the liquid crystal thereof is substantially exhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the alignment of liquid crystals used when producing liquid crystal elements such as liquid crystal display elements and liquid crystal-light shutter arrays, and more specifically, the present invention relates to a method for controlling the alignment of liquid crystals used in producing liquid crystal elements such as liquid crystal display elements and liquid crystal-optical shutter arrays. , relates to a liquid crystal alignment control method that improves display and drive characteristics.

Conventionally, liquid crystal display elements display images or information by arranging a group of IT scanning rods and a group of signal electrodes in the shape of an IJ square, and filling a liquid crystal compound between the electrodes to form a large number of pixels. well known.

The driving method for this display element is time-division driving, in which an address signal is selectively and periodically applied to a group of scanning electrodes, and a predetermined information signal is selectively applied in parallel to a group of signal electrodes in synchronization with the address signal. However, this display element and its driving method have major and fatal drawbacks as described below.

In other words, it is difficult to increase the pixel density (or increase the screen size).Among conventional liquid crystals, it has a relatively high response speed and low power consumption, so it is used as a display device. Most of them are, for example, M, 5cha
dt and W, He1frich “Applied Ph
ysics Letters”Vo, 18, N[L4(
1971, 2, 15), P, 127-128 °'Vo
ltage-Dependent 0ptical
Activity of a TwistedNema
This type of liquid crystal uses a TN (twisted nematic) type liquid crystal displayed in "Tic Liquid Crystal", and this type of liquid crystal is made of liquid crystal molecules that have a positive dielectric anisotropy p in the absence of an electric field. A (helical structure) is formed in the layer thickness direction, and a structure in which the liquid crystal molecules are arranged in parallel on both electrode surfaces is formed.

On the other hand, when an electric field is applied, nematic liquid crystals having positive dielectric anisotropy are aligned L in the direction of the electric field, resulting in optical modulation. When a display element is constructed using this type of liquid crystal with an IJ electrode structure, liquid crystal molecules are arranged perpendicularly to the electrode surface in the area where both the scanning electrode and the signal electrode are selected (selection point). A voltage equal to or higher than the required threshold is applied, and no voltage is applied to areas where neither the scanning electrode nor the signal electrode is selected (non-selected points), and therefore the liquid crystal molecules maintain a stable alignment parallel to the electrode surfaces. By arranging linear polarizers in a cross nicol relationship under -E of such a liquid crystal cell, light does not pass through selected points, but light passes through non-selected points, making it possible to use it as an image element. It becomes possible.

However, if an IJ square electrode f2 structure is configured, there will be a region where the scan electrode is not selected and the signal type bar is not selected, or a region where the scan electrode is not selected and the signal electrode is selected (the so-called " A finite electric field is also applied to the half-selected point. If the difference between the voltage applied to the selected point and the voltage applied to the half-selected point is sufficiently large, and the voltage threshold required to align the liquid crystal molecules perpendicular to the electric field is set to a voltage value in between, the display The element operates normally, but when the number of scanning lines (N) is increased, the time (time) during which an effective electric field is applied to one selected point while scanning the entire screen (1 arene) is increased. duty ratio) decreases at a rate of 1/N. For this reason, when repeated scanning is performed, the effective voltage difference between selected points and non-selected points becomes smaller as the number of scanning lines increases, resulting in a decrease in image contrast and crosstalk. This is a drawback that is difficult to avoid. This phenomenon occurs in liquid crystals that do not have bistability (
The stable state is when the liquid crystal molecules are oriented horizontally with respect to the electrode surface, and the liquid crystal molecules are oriented vertically only while an electric field is effectively applied. This is essentially an unavoidable problem that arises when performing an edge-back scan. To improve this point,
Voltage averaging method, dual-frequency drive method, multiplex IJ method, etc. have already been proposed, but all of these methods are insufficient, and increasing the screen size and density of display elements requires an increase in the number of scanning lines. At present, it has reached a plateau due to the inability to increase the number of pixels sufficiently.On the other hand, if we look at the printer field, we can see that speed is increasing as a means of obtaining notebook power using electrical signals as input, both in terms of pixel density. Laser beam printers (LBPs), which provide electrical image signals in the form of light to an electrophotographic photoreceptor, are currently the most superior from this point of view. However, LBP has drawbacks such as: 1. The printer is large in size; 2. It requires a high-speed driving unit like a polygon scanner. In order to overcome these drawbacks, a liquid crystal shutter array has been proposed as a confectionery that converts electrical signals into optical signals. However, when providing pixel signals using a liquid crystal shutter array, for example, in order to input pixel signals at a rate of 16 dat/mm into a length of 210 mm, it requires more than 3,000 signal generating units. In order to give independent signals to each, it was originally necessary to wire lead glands that send signals to all of the signal generating parts, which was difficult to manufacture, so I
Attempts have been made to provide LINE pixel signals in a time-division manner using a signal generating section divided into several lines. In this way, the pole for applying the signal can be made common to the PM number of signal generating sections, and the actual wiring can be significantly reduced. However, in this case, if we increase the number of rows a (N) using a liquid crystal that does not have bistability, as is usually done, the signal B'''
The disadvantages are that j l: ij becomes substantially 1 ha, resulting in a decrease in the amount of light that can be obtained on the photoreceptor, and the problem of crosstalk.

To overcome these shortcomings of conventional liquid crystal confectionery, the use of bistable liquid crystal elements has been proposed by C1ark and Lage 1 (
l+! f, Publication No. 1972-107216, U.S. Patent No. 4
367924, etc.). Liquid crystals with bistability are generally chiral smectic C phase (S+nC
``) or a forced liquid crystal with an H phase (SmH'') may be used. This liquid crystal has a bistable state consisting of a first optically stable state and a second optically stable state with respect to an electric field. Therefore, unlike the optical modulation element used in the above-mentioned TN liquid crystal, for example, one 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. Furthermore, this type of liquid crystal has the property of very quickly taking one of the above two stable states in response to an applied electric field and maintaining that state when no electric field is applied. By utilizing such properties, it is possible to obtain substantial improvements over many of the problems of the conventional TN type element described above.This point will be discussed below in connection with the present invention. , will be explained in more detail. However, in order for an optical modulation element using this bistable liquid crystal to exhibit predetermined drive characteristics, the liquid crystal placed between a pair of parallel substrates must be adjusted to the applied state of an electric field. Regardless, it is necessary that the molecules be in a state of molecular arrangement such that conversion between the two stable states occurs effectively, e.g. smc* or S+n)4.
For a ferroelectric liquid crystal with a phase, a layer of liquid crystal molecules having an SmC or SmH* phase is perpendicular to the substrate surface, so that the liquid crystal molecular axes are approximately parallel to the substrate surface. domain (monodomain) needs to be formed. However, in conventional optical modulation elements using liquid crystals with bistability, the alignment state of the liquid crystals having such a monodomain structure was not always formed satisfactorily, and sufficient characteristics could not be obtained. The reality is that in order to give such an orientation state, 56
A method of applying b%, a method of applying shear force, etc. have been proposed. However, none of these methods always gave satisfactory results at t2. For example, the method of applying a magnetic field requires a large-scale device and is incompatible with a W-layer cell with good operating characteristics, and the method of applying a shear force is
This method has the disadvantage that it is incompatible with the method of injecting liquid crystal after creating the cell.

By the way, in the device using the TN type liquid crystal as mentioned above,
Methods for forming monodomains of liquid crystal molecules in a state parallel to the root plane include, for example, a method of rubbing the surface of the substrate with something like cloth (rubbing) and a method of diagonally depositing SiO. .

For example, the liquid crystal that is in contact with the surface of the substrate that has been subjected to creeping is given a directionality, and the liquid crystal molecules preferentially align in that direction, which has the lowest energy (that is, is stable).
state. Such a lined surface has the effect of preferentially arranging liquid crystal molecules in one direction. A structure having a plane to which this orientation effect is applied is, for example, WJ [elfric
h and M, 5chadt, Canadian Patent No. 1010136, etc. In addition to the method of creating an alignment effect using this rubbing method, a structure with a plane formed by obliquely vapor depositing SiO or 5i02 on a substrate is used.
A plane with uniaxial anisotropy across iO and SiO2 directs liquid crystal molecules in one direction.In order to create a liquid crystal element, alignment control methods such as rubbing and oblique evaporation are one of the preferred methods. However, when alignment is controlled using these methods for liquid crystals that have bistability, a plane is formed that has a wall effect that causes the liquid crystals to be oriented in only one direction.
This has the disadvantage of inhibiting bistability to electric fields, high-speed response, and monodomain formation.

In view of the above-mentioned circumstances, the main object of the present invention is to provide a bistable device that has potential suitability as a display element with high-speed response, high-density pixels, and a large area, or an optical shutter with a high shutter speed. A liquid crystal alignment control method that can fully demonstrate its characteristics by improving monodomain formation l, c or initial alignment, which has been a problem in the past in optical modulation elements using liquid crystals. Our goal is to provide the following.

As a result of further research for the above-mentioned purpose, the present inventors have found that, in particular, liquid crystal materials have a tendency toward uniaxial anisotropy (e.g., low-temperature state such as SmA (smectic A)) rather than another phase (e.g., high-temperature state such as isotokic phase). Focusing on the orientation during the transition temperature cooling process, we found that when a phase transition occurs from another phase (high temperature sum) to the -axial anisotropic phase, the space between another phase region and the -axial anisotropic phase region At the phase interface, the uniaxially anisotropic molecular axes generated by a new phase transition are oriented parallel to the already formed uniaxially anisotropic liquid crystal molecule alignment direction, and moreover, the -axis It has been found that when the direction in which the anisotropic phase region grows and the orientation direction of the liquid crystal molecules are orthogonal to each other, the monodomain-axial heterotropic phase grows extremely stably. Furthermore, the present inventors constructed a structure having a horizontally oriented side wall surface as a nucleation member (-
By arranging the initial uniaxially anisotropic nucleus as a monodomain in which the liquid crystal molecules are oriented parallel to the nucleation member Sex 6! This conclusion can be formed as a square:
5i'', it has been found that a liquid crystal element having a structure that can satisfy the operating characteristics of the element based on the bistability of the liquid crystal and the monodomain property of the liquid crystal layer can be obtained.

The present invention is based on the above-mentioned knowledge, and the method for controlling liquid crystal alignment according to the present invention is to create uniaxial anisotropy (e.g., smecti phase, nematic phase) between a pair of substrates at a predetermined temperature. The heating means is relatively moved toward one end (Ip) over the entire or partial surface of the cell structure having the compound, and the heating means is moved uniaxially by moving the heating means. Another phase on the higher temperature side than the anisotropy (e.g.
Heavy equipment has reached the point where an 1111I anisotropic phase is formed in the cooling process that occurs following the heating process that produces the Tokichi phase, nematic phase, and cholesteric phase.

Hereinafter, this publication will be explained in detail, referring to the drawings as necessary.

Particularly suitable liquid crystal materials for use in the present invention are liquid crystals with bistability, and chiral smectic liquid crystals with ferroelectricity are also preferred, among which chiral smectic C phase (SmC'') or H phase ( S mIf
”) is suitable.

Regarding this ferroelectric liquid crystal, please refer to “LE JOURNAL
DE PIIYSIOUE LETTER8” 36
(L-69) 1975.

“Ferroelectric Liquid Cry
stalsJ; “Applied physics
Let-ters” 36 (11) 1980, rsu
bmicro 5econd B1-5table E
electrooptic Switching in L
iquid CrystalsJ; “Solid State Physics 016
C141) 1981 "Quasi-crystal" and the like, and the ferroelectric liquid crystal disclosed in these can be used in the present invention.

More specifically, examples of ferroelectric liquid crystal compounds used in the method of the present invention include decyloxybenzylidene-P-amino-2-methylbutylcinnamate (DOBAMBC).
, hercyloxypendilithene-P-amino-2-chloropropylcinnamate (HOBACPC) and 4
- o -(2-methyl)-butyl resol silidan-4
-octylaniline (MBRA8) and the like.

FIG. 1 schematically depicts an example of a cell for explaining the operation of a ferroelectric liquid crystal. 11 and 11 are In2
O2, 5n02 or ITO (Indium-Ti
It is a substrate (glass plate) coated with a transparent electrode made of a thin film such as
SmC phase or Sm
H'' phase liquid crystal is sealed. A thick line 13 represents a liquid crystal molecule, and this liquid crystal molecule 13 has a dipole moment (Pl) 14 in a direction perpendicular to the molecule. When a voltage higher than a certain threshold is applied between the electrodes on the substrates 11 and 11, the helical structure of the liquid crystal molecules 13 is unraveled, and the liquid crystal molecules 13 are aligned in the direction such that the dipole moment (Pf) 14 is all directed in the direction of the electric field. The liquid crystal molecules 13 have an elongated shape and exhibit refractive index anisotropy in the long axis direction and short axis direction. If you put it,
It is easily understood that this is a liquid crystal optical modulation element whose optical characteristics change depending on the polarity of applied voltage.

The liquid crystal cell preferably used in the liquid crystal element of the present invention can have a sufficiently thin thickness (for example, 10 μm or less). As the liquid crystal layer becomes thinner, the helical structure of the liquid crystal molecules unwinds and becomes a non-helical structure even when no electric field is applied, as shown in Figure 2, and its dipole moment P or P points upward (24 ) or downward (2
4). In such a cell, the second
As shown in the figure, electric field E or E with different polarity above a certain darkness value
is applied by the voltage application means 21 and 21, the dipole moment changes its direction upward 24 or downward 24 in response to the electric field E or the electric field vector of E, and accordingly, the liquid crystal molecules enter the first stable state 23. or the second stable state 23.

As mentioned earlier, there are two advantages to using such ferroelectricity as a liquid crystal 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, for example with reference to FIG. 2, when an electric field E is applied, the liquid crystal molecules are oriented in a first stable state 23; 23 and changes the direction of the molecule, but it remains in this state even after the electric field is turned off. Further, as long as the applied electric field E does not exceed a certain threshold value, each orientation state is maintained. In order to effectively realize such fast response speed and 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
It is difficult to form a highly monodomain cell in which the layer having "phase or SmH" is aligned perpendicularly to the substrate surface and the liquid crystal molecules are aligned approximately parallel to the substrate surface, and this point It is the main objective of the present invention to provide a solution to the problem.

@3 Figure (A) is a perspective view schematically showing the liquid crystal alignment control method of the present invention, and Figure 3 is a cross-sectional view thereof.

The liquid crystal cell 100 shown in FIG. 3 has a cell structure in which a pair of substrates 101 and 101 made of glass plates or plastic plates are held at a predetermined distance by a spacer 103, and the pair of substrates are bonded with an adhesive 106. Further, on the substrate 101, an electrode group (for example, a scanning voltage application electrode group in a matrix electrode structure) consisting of a plurality of transparent electrodes 102 is formed in a predetermined number of turns, such as a strip pattern. There is C. On the substrate 101, an electrode group for applying a signal voltage is formed among a plurality of transparent electrodes 102 that intersect with the transparent electrode 102 described above.

Such substrates 101 and 101 include, for example, silicon oxide, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide, boron nitride, polyvinyl alcohol, polyimide. , polyamideimide, polyesterimide, polyparaxylerin, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyamide, polystyrene, cellulose resin, melamine resin, insulating film formed using resin, acrylic resin, etc. (not shown) may be provided. This insulating film also has the advantage of being able to prevent the generation of current caused by trace amounts of impurities contained in the liquid crystal layer 104, and therefore does not deteriorate the liquid crystal compound even if the operation is repeated.

Below, DOBAMB, a liquid crystal material that exhibits ferroelectricity at a certain temperature,
Taking C as an example, a method for controlling the alignment of the liquid crystal layer 104 will be explained in detail using FIG.

First, a liquid crystal cell 100 in which DOBAMBC is sealed
is set in a heating case (not shown) that uniformly heats the entire cell. Next, the preparation of the heating case is controlled so that the average temperature of the cell is, for example, 70° C. to 90° C., and the liquid crystal layer 104 of the SmA phase or SmC” phase is formed. In the state before applying the orientation control method, no SmA or SmC monodomains are formed.

Here, a heating element 107 is moved in the direction of the missing plant 108 as a heating means. At this time, the heating element 107 causes Sm
The liquid crystal layer 104 in the area where the temperature has risen above the phase transition temperature from A to isotropic phase (approximately 118° C.) enters the isobic phase state, but as the heating element 107 continues to move toward the defect 108,
In this region, a cooling process immediately occurs from the Tokiyoshi phase state,
Therefore, the phase transition temperature from Tokiyoshi phase to SmA (approximately 116℃
) When the temperature is lowered to below, SmA oriented in one direction
monodomains are formed.

In this case, as a more preferable specific example of the present invention,
A member that promotes the generation of a liquid crystal layer (hereinafter referred to as a "nucleation member"5)
) 105 can be included in the liquid crystal cell 100. That is, when the nucleation member 105 is used, due to the heating by the heating element 107, the temperature in the vicinity of the side wall surface 105 of the nucleation member 105 becomes higher than the phase transition temperature from SmA to the isotropic phase. After that, the heating element 107 moves in the direction of the missing plant, causing a temperature decreasing process, and the Tokichi phase → S m
Below the phase transition temperature to A, the SmA of liquid crystal molecules aligned in one direction is
is formed. Furthermore, SmA generated by the phase transition from Tokichi phase to SmA that continuously occurs due to the movement of the heating element 107.
is subjected to a forcing force that causes an alignment parallel to the liquid crystal alignment generated near the side wall surface 105 of the aforementioned nucleation member 105,
As a result, a monodomain is formed in which the total number of rows is parallel to the longitudinal direction of the wall surface 105.

Furthermore, since the spacer member 103 can have the same function as the nucleation member 105, which will be described in detail later, the spacer member 103 can be inserted into the liquid crystal cell 100 while the heating element 107 is being moved over the liquid crystal cell 100. Even if there exists
This does not pose any obstacle to the formation of monodomains of SmA, SmC, or SmH. In particular, in a preferred embodiment, the spacer member 103 is suitably of the same old material as the nucleating member 105 described above. That is, the substrate 101
After forming a film of a predetermined resin or inorganic substance on top of the spacer member 103, etching treatment is performed using a predetermined method.
and the nucleation member 105 can be formed simultaneously. In addition, instead of using the above-mentioned etching method, a strip-shaped film, glass fiber, or highly oriented fibers such as those used in the nucleation member 105 described later can be placed between the substrates 101.

The nucleation member 105 can be made of a band-shaped film or glass fiber that has been given a rubbing effect on the side wall surface 105 by cutting a polyester film or a polyimide film with a metal blade or a diamond blade. Highly oriented fibers created by spinning polymeric liquid crystals into fibers, known as anisotropic solutions (lyotropic liquid crystals) or anisotropic melts of polymeric substances (thermotropic liquid crystals), can be used. . As the polymeric liquid crystal, one having a nematic phase or a smectic phase is suitable.

Examples of polymeric liquid crystals used to form cylindrical oriented fibers include poly(p-phenylene terephthalamide).
Typical fibers include fibers spun from a liquid crystal state of a sulfuric acid solution of poly(p-benzamide) or a dimethylacetamide solution of poly(p-benzamide). In addition, poly(amide)
hydrazide) and polyhydrazide, such as sulfuric acid or fluorosulfuric acid.
-phenylenebenzobisoxazole) and poly(p
liquid crystal solutions of polyphosphoric acid, methylsulfonic acid, etc. of -phenylinebenzobisthiazole), rose-hydroxybenzoic acid, 1,2-bis(rose-carboxyphenoxy)ethane, terephthalic acid and substituted or unsubstituted Liquid crystalline melt of polyester formed from hydroquinone, rose-hydroxybenzoic acid, j,2-bis(
A liquid crystalline melt of a polyester produced from rose-carboxyphenoxy)ethane, terephthalic acid and bisphenol A or bisphenol A diacetate, and a liquid crystalline melt of a polyester represented by the following general formula (1) or (2). Examples include fibers obtained by spinning.

General formula (]) (n = 2 to 11 in the formula) By using such fibers in the spacer member 104, the liquid crystal in contact with the highly oriented surface of the fibers is oriented along the orientation direction of the fibers. It is something that can be done.

In addition, in the case of smooth glass without the notch shown in the substrate 101, 5iO9SiO2 is placed on the glass substrate.
After forming a film of SiO, 5j02 or TiO, a band-shaped SiO, 5j02 or TiO film having a side wall surface 105 formed by etching with an oblique ion beam is used as a nucleation member 1.
It can be used as 05. Further, on the substrate 101, silicon nitride with higher hardness, silicon nitride containing hydrogen, silicon carbide, silicon carbide containing hydrogen, Ti1lIA nitride, boron nitride containing hydrogen, cerium oxide, oxide An insulating film (not shown) is formed by forming a film using a compound such as silicon, aluminum oxide, zirconia or magnesium fluoride, and this soil is coated with polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, etc., which have lower hardness. Resins such as polyparaxylerin, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, acrylic resin, or photosensitive polyimide, photosensitive polyamide, Cyclized rubber photoresist, phenol borac photoresist or electron beam photoresist (polymethyl methacrylate,
After forming a film of (epoxidized 1,4-polybutadiene, etc.), etching is performed using a normal photolithography method to create a nucleation member 105, and then a rubbing effect is imparted to this side wall surface 105 by rubbing. Can be done. At this time, the top of the nucleation member 105 may also be in contact with the substrate 101 side.

Further, in the liquid crystal cell 100 used in the present invention, a planar heating element 113 can be provided on the back surface of the substrate 101. This planar heating element 113 heats the entire liquid crystal cell 100, and can be used, for example, in the liquid crystal layer, or as described above, which is used to uniformly heat the liquid crystal layer 104 to make the liquid crystal layer 104 into an equi-auspicious phase. Can be used in place of a case. The heating element 107 used as a heating means has a cell structure at a temperature sufficient to cause SmA, SmC, or SmH" to undergo a phase transition to an isobic phase, a nematic phase, or a cholesteric phase on the higher temperature side than SmA or SmC" during the temperature rising process. body 100
is heated, and the heating element 107 is moved in the direction of the defect 108 at a moving speed sufficient to cause a phase transition to SmA or SmC during the cooling process. The movement speed at this time is
Although not generally defined, 1 mm/h to 5 gm/h
The degree is appropriate.

Furthermore, in the method of the present invention, the heating element 107 is moved from one rose to the other with respect to the liquid crystal cell 100 by moving the support base 110 in the direction of the missing stock 111 by rotating the roller 112 while keeping the heating element 107 fixed. You may move it.

The heating element 107 used in such a method may be, for example, wire-shaped, roll-shaped, rod-shaped, etc.

A resistive heating element such as tin oxide or indium oxide can be used. When these heating bodies are wire-shaped, roll-shaped, or rod-shaped, their diameter is 0.
1-~514 lightning degree 1 preferably 0.5 mπ ~ 2 mm is suitable, and in the case of a plate-like X, S & band-like shape) the width of the vertex &! Approximately 0.1 mFL to 5 mFL, preferably 0.5 mFL to 2 mFL, is suitable.

In particular, a band-shaped heating element 1071, such as that shown in FIG. 4, is suitable. Heater 201 shown in FIG.
This has a structure in which a band-shaped heating element 107 made of a nickel-chromium alloy film formed by vapor deposition is provided on the top surface of a horizontal support 202 made of an insulator such as ceramic.

Furthermore, a concentrating infrared heater 301 as shown in FIG. 5 can be applied as a heating means.
It has a structure in which an infrared lamp 302 is housed in a hood equipped with a condenser reflector 303 and a condensing reflector 303.

When using the heating means shown in FIGS. 4 and 5, the heating means may be moved in the direction of the chip 108, or the liquid crystal cell 100 may be moved in the direction of the chip 111. Any means may be used as long as the liquid crystal cell 100 can be moved relative to the heating means.

! Such a liquid crystal cell 100 has substrates 101 and 101 on both sides having cells in a crossed nicol state or a parallel nicol state.
Pairs of polarizers are arranged, respectively, so that the electrodes 102 and 102
When a voltage is applied between them, optical modulation will occur.

Figures 6 to 8 show examples of movement of the liquid crystal element of the present invention.

Figure 6 shows a matrix with a ferroelectric liquid crystal compound sandwiched in the middle.
FIG. 4 is a schematic diagram of a cell 41 having an IJ square electrode structure. 4
2 is a scanning electrode group, and 43 is a signal electrode group. 7th
Figures (a) and (bl) show selected scanning electrodes 42, respectively.
(s) and the electrical signals given to the other scanning electrodes (unselected scanning electrodes) 42(n), and FIGS. 6(c) and (di are the selected signal electrodes 43(n), respectively). The electric signal given to sl, the unselected signal TM, and the electric signal sent to Wi43(n) are shown. In FIG. 7 (al to (d)), the horizontal axis represents time and the vertical axis represents voltage. For example, in the case of displaying a moving image, the scanning electrode group 42 is selected periodically.Now, in order to provide the first stable state of the bistable liquid crystal cell, the threshold voltage is set to th. .

and the threshold voltage for providing the second stable state is −v
Assuming th2, the electric signal given to the selected scanning differential electrode 42(8) is V at phase (time) ti and 1 at phase (time t2), as shown in FIG. 7(a). It is an alternating voltage like that.

Further, the other scanning electrodes 42(n) are in a grounded state as shown in FIG. 7(b), and have an electrical signal of 0.

On the other hand, the electric signal applied to the selected signal electrode 43(s) is v as shown in FIG. 7(c), and the electric signal applied to the unselected signal electrode 43(n) is v.
As shown in Figure (d), <-V. In the above, the voltage V is V < Vth 1 < 2 V and -V> - Vth2)
It is set to a desired value that satisfies -2V. FIG. 8 shows the voltage waveforms applied to each 11ii element when such an electric signal is applied. 8 (at to (dl) correspond to pixels A, B, C, and D in FIG. 6, respectively. In other words, as is clear from FIG. 8, in the image iA on the selected scanning line, Threshold value v thl at phase t2
A voltage exceeding 2V is applied. Further, to the pixel B existing on the same scanning line, a voltage -2v exceeding the threshold value -vth2 is applied at phase t1. Therefore, depending on whether or not a signal electrode is selected on the selected scanning electrode line, if selected, the liquid crystal molecules are aligned in the first stable state, and if not selected, the liquid crystal molecules are aligned in the first stable state. Align the orientation to the stable state of 2. In any case, it has nothing to do with the previous history of each pixel.

On the other hand, as shown in pixels C and D, on unselected scanning lines, the voltage applied to all pixels C and D is +V or -■, neither of which exceeds the threshold voltage. Therefore, the liquid crystal molecules in each pixel c2:D do not change their orientation state (they maintain the orientation corresponding to the signal state at the time of the previous scan. In other words, when the scanning electrode is selected, One line of signals is written,
- The signal state can be maintained until the next selection after the end of the frame. Therefore, even if the number of scanning electrodes increases, the actual duty ratio does not change, and contrast reduction and crosstalk do not occur at all. At this time, the value of the voltage value V and the phase (t1 + t2 > 2T) depend on the liquid crystal material used and the thickness K of the cell, but it is usually 0.1 psec to 2 m5 at 3 volts to 7 volts.
A range of eC is used. Therefore, in this case, the electrical signal applied to the selected scanning electrode is in the first stable state (
any change from a stable state (supposed to be a "bright" state when converted to an optical signal) to a second stable state (supposed to be a "dark" state when converted to an optical signal), or vice versa. I can wake up.

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

[Example 1] Striped I with a pitch of 100 μm and a width of 62.5 μm
A 2.5 μm deep incision was provided at the end of the glass substrate provided with T 011'lK as an electrode so as to be parallel to the striped ITO film.

Next, a polyimide forming solution (Hitachi Chemical Co., Ltd.'s "PIQ" with a non-volatile content concentration of 14.5 wt%) was applied onto the substrate, excluding the cut portion, for 10 seconds using a spinner coating machine rotating at 3,000 rpm. It was coated and heated at 120°C for 30 minutes to form a 2μ film.Then, a positive resist solution (“AZ1350” manufactured by Hipley) was applied.
'') was applied with a spinner and prebaked. This resist layer was exposed using a striped mask with a mask width of 8 μm and a pitch of 100 μm. Next, a developer containing tetramethylammonium hydroxide “MF” was applied.
Develop at 312''K, register 7) of exposed area
After etching the JIG' and the underlying polyimide film to form through holes, washing with water and drying, the non-luminescent resist (M) was removed using methyl ethyl ketone. After that, it was cured by heating at 200°C for 60 minutes and at 350°C for 30 minutes, and P T Q, (
(A) An electrode plate was prepared by forming a polyimide (polyimide) spacer layer.

A Mylar film (registered product of DuPont, USA; polyethylene terephthalate film) cut with a metal blade was placed as a nucleation member in the cut portion of the substrate thus prepared.

Next, on the glass substrate, a width of 625 mm was formed with a pitch of 100 μm.
An electrode plate (B) was prepared by providing micrometer striped electrodes. (B) After applying epoxy adhesive to the periphery of the electrode plate by screen printing except for the area that will become the injection hole, They were stacked perpendicularly and the adhesive was cured under constant Qr curing conditions to create a cell.

After that, DOBAMBC of the Tokichi phase was obtained by the page nitrogen injection method.
is injected into the cell from the injection port, and this DOBAMBC
After installing a pair of polarizers in a crossed nicol state on both sides of the cell injected with the polarizer, the polarizers were placed in a heating case K whose flow rate was controlled at 90°C.
When we analyzed the results, we found that 5rnC was formed, but it was confirmed that no monodomain was formed.

The diameter of this liquid crystal cell (12
3rd place heater (chrome alloy) on mm no fire
] As shown in Figure 1, the wire heater was placed near and parallel to the nucleation member provided in the cell, and then a current was applied to the wire heater to generate heat. At this time, the temperature of the liquid crystal cell heated by the wire heater is 120'C to 140'C.
After confirming that the wire heater
It was moved in the direction of

After a pair of polarizers were placed on both sides of the liquid crystal thus created in a crossed nicol state, it was observed under a microscope while maintained at a temperature of 90°C, and it was confirmed that monodomain SmC was formed. Ta.

Now, the alignment is completed through the steps described above, but even though the monodomains appear to be uniformly perfected, in reality, severe pressure is applied between the electrodes 102 and 102 to achieve liquid crystal optical modulation. When examining the switching characteristics of an element, non-uniformity in optical contrast and response speed may occur depending on the region. This phenomenon is thought to be caused by structural distortion caused by the movement of the heater during orientation. On the other hand, after the alignment process is completed, the temperature of the case is increased to cause the liquid crystal to undergo a -111 phase transition from the SmC'' phase to the SmA phase, and then the temperature of the case is gradually increased to the SmC'' state again. By lowering the pressure, the above-mentioned distortions are eliminated by the slow phase formation.

[Brief explanation of the drawing]

1 and 2 are perspective views showing a liquid crystal cell used in the present invention. FIG. 3(A) is a perspective view schematically showing the method of the present invention, and FIG. 3(B) is a sectional view thereof. FIG. 4 is a perspective view schematically showing another method of the present invention. FIG. 5 is a cross-sectional view schematically representing another method of the present invention. FIG. 6 is a plan view schematically showing the electrode structure of the liquid crystal element used in the present invention. Figure 7(a)-(d)
) is an explanatory diagram showing signals for driving a liquid crystal element used in the present invention. FIGS. 8(a) to 8(d) are explanatory diagrams showing voltage waveforms applied to each pixel. - 105; Nucleus generation member 105; [lI+1 wall surface 106 of nuclear generation center]; Inviting agent 107; Source heating element 108; Movement direction of heating means 109; Surface 110 of substrate 100; Support stand 111; Movement of liquid crystal cell Direction 112; Roller 113; Planar heating elements 201, 301; Heater 202; Wedge-shaped support 302; Infrared lamp 303; Concentrating reflector 304; Slit opening Patent applicant Canon Co., Ltd. (b) ---Vth1 cd) 1--------1/LZ

Claims (11)

[Claims] (1) Over the entire or partial surface of a cell structure having a compound that becomes a uniaxial anisotropic phase at a predetermined temperature between a pair of plates,
From a temperature raising process in which a heating means is relatively moved from one end toward the other end, and another phase with a higher temperature flJ than the uniaxial anisotropic phase is generated by the movement of the heating means. A liquid crystal orientation control method characterized by the formation of a uniaxial anisotropic phase during a subsequent temperature cooling process. (2) The cell structure has a nucleation member, and the nucleation member initially generates an axially anisotropic phase aligned in one direction. Orientation control method. (3) The liquid crystal orientation control method according to claim 2, wherein the nucleation member is a band-shaped sound material. (4) The liquid crystal orientation control method according to claim 2 or 3, wherein the nucleation member is a member made of resin or an inorganic substance. (5) The resin is polyvinyl alcohol, polyimide,
Polyamideimide, polyesterimide, polyparaxylylene, polyester, polycarbonate, polyvinyl acecool, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin,
5. The liquid crystal orientation control method according to claim 4, wherein the resin is at least one selected from the resin group consisting of Yuria resin, acrylic resin, and photoresist resin. (6) The liquid crystal orientation control method according to claim 1, wherein the cell structure includes a plurality of spacer members. (7) The liquid crystal alignment control method according to claim 6, wherein the spacer member is a member having a band-like shape. (8) The liquid crystal orientation control method according to claim 1, wherein the -axial anisotropic phase is a smectic phase. (9) The liquid crystal orientation control method according to claim 8, wherein the smectic phase is a smectic A phase. (10) The liquid crystal orientation control method according to claim 9, in which the smectic human phase turns into a chiral smectic C phase or H phase upon cooling. (11) The liquid crystal orientation control method according to claim 10, wherein the chiral smectic C phase or H phase has a non-helical structure. (2) The liquid crystal orientation control method according to claim 1, wherein the other phase on the higher temperature side than the -axial anisotropic phase is an isotropic phase, a nematic phase, or a cholesteric phase.