JPS60118823A - Method for controlling orientation of liquid crystal and element to be used in said method - Google Patents

Abstract

PURPOSE:To obtain an element having a high-speed response property, a high density and suitable for display on a large area by generating first the uniaxial anisotrophic phase of a liquid crystal at the boundary of a cylindrical member between a pair of base plates and decreasing the temp. of the phase at the side of a temp. high than the anisotropic phase thereby arranging the liquid crystal in the same direction as the uniaxial anisotrophic phase. CONSTITUTION:A cylindrical member 104 consisting of glass fibers, etc. is provided in a recess on a base plate 101 side between a pair of liquid crystal base plates 101 and 101' so as to have a chiral smectic C phase (SmC*) or H phase (SmH*) with a ferroelectric liquid crystal 103 such as disiloxybenzilidene-P-amino-2-methylbutyl cinnamate (DOBAMBC) or the like and the base plates 101, 101' are joined by using an adhesive agent 106. A heating electrode 105 is provided on the side of the plate 101 opposite to the member 104 and the liquid crystal is kept at a high temp. The temp. of the liquid crystal arranged in parallel with the uniaxial anisotropic phase is so decreased as to transfer the phase to the boundary 104' with the member 104. The monodomain arranged in the direction perpendicular to the plane of the plates 101, 101' is thus formed. The driving speed of the liquid crystal is thus increased and the high-density display characteristic over a large area is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal alignment control method used in producing liquid crystal elements such as liquid crystal display elements and liquid crystal-optical shutter arrays, and elements used in the method, and more specifically relates to an initial alignment control method of liquid crystal molecules. 1. of liquid crystals with improved display and driving characteristics. This invention relates to a surface control method and an element used in the method.

Conventionally, a liquid crystal display element displays images or information by arranging a scanning electrode group and a signal electrode group in a matrix, 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 sequentially 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 better to increase the pixel density or make the screen larger.
It's a bad thing. Among conventional liquid crystals, most of them are practically used as display elements, for example, M, 8, because they have a relatively high response speed and low power consumption.
Written by chadt and W, He1frich @Applied
Physics Letters”Vo, 18,
/l64 (1971, 2, 15), P, 127-12B
@vo:ttage-, Dependent 0pt
ical Activity Of a Twist
dNematic Liquid Crystal'
This type of liquid crystal uses the TN (twistea nematic) type liquid crystal shown in Figure 1. This type of liquid crystal is created by twisting the molecules of the nematic liquid crystal, which has positive antistatic anisotropy in an unbounded state, in the thickness direction of the liquid crystal layer. The liquid crystal molecules form a parallel structure on both positive electrode surfaces (helical structure). On the other hand, when an electric field is applied, nematic liquid crystals with positive feeding anisotropy are aligned in the direction of the electric field, resulting in optical modulation. When a display element (R) is formed using this type of liquid crystal with a matrix i-pole structure, liquid crystal molecules are arranged perpendicularly to the electrode surface in the region where both the scanning electrode and the signal electrode are selected (selection point). A voltage equal to or higher than the required FN value is applied, and no voltage is applied to areas where neither the scanning electrode nor the signal electrode is selected (unselected points), and therefore the liquid crystal molecules 11j maintain a stable alignment parallel to the polar plane. By arranging linear polarizers above and below such a liquid crystal cell in a cross-Nicol relationship with each other, the light does not pass through selected points, but the original light passes through non-selected points, making it possible to However, when a matrix electrode structure is configured, there are areas where scan electrodes are selected and signal electrodes are not selected, or areas where scan at is not selected and signal electrodes are selected (in some places). The difference between the voltage applied to the 6 selection points (where the electric field is finitely applied even to the "half selection point") and the voltage applied to the half selection point is sufficiently large, and the voltage required to align the liquid crystal molecules directly to the electric field If the threshold is set to an intermediate voltage value, the display element will operate normally, but if the number of scanning lines (N) is increased, the The time during which an effective electric field is applied to one selection point (auty ratio) is 1
/N. During this run, the effective 1 applied to the Ga selection point and the non-η selection point when scanning is repeated.
The direct voltage difference becomes smaller as the number of scanning lines increases, and as a result, a reduction in image contrast and crosstalk are unavoidable and become drawbacks. This phenomenon occurs only when the liquid crystal molecules are horizontally aligned, and only while the bistability is effectively applied. This is a difficult problem in terms of wood tone that occurs when driving using the target accumulation effect (i.e., scanning back and forth).This point has been improved. In order to do this, voltage averaging method, two frequency mA 4
The jb method and the multiplex matrix method have already been proposed, but all of them are non-light-emitting, and have reached a plateau due to larger double-sided display devices, higher density, and the inability to sufficiently increase the number of display elements. This is the current situation.

On the other hand, looking at the field of printers, laser beam printers provide electrical image signals in the form of light to electrophotographic photoreceptors in terms of both pixel density and speed, as a means of obtaining hard copies using electrical signals as input. (LBP) is currently the best. However, LBP has drawbacks such as: 1. The printer is large; 2. High-speed drive parts like polygon scanners generate noise, and strict mechanical precision is required. . In order to overcome these drawbacks, a liquid crystal shutter array has been proposed as an element that converts electrical signals into optical signals. When Totoro uses a liquid crystal shutter array to provide pixel signals, for example, in order to write pixel signals at a rate of 16 aot/h within a length of 210 h, it must have more than 3000 signal generators. In order to give independent signals to each of them, it was originally necessary to place an IJ-domain that sends signals to all of the signal generating parts, and manufacturing Ueda 1! It was T#.

For this reason, an attempt has been made to divide the pixel signal for one (line) of the IL process into several lines (from the tV light generation section and give it in time division. This is because it can be made common to the initial number of signal generators, and the actual η device can be significantly reduced.

However, in this case, if the number of lines (N) is increased using a liquid crystal that does not have bistability, as is usually done, the signal ON time is essentially 17N, and the image on the photoreceptor is increased. The i! There is 1# point. - To improve the drawbacks of conventional liquid crystal devices, the use of bistable liquid crystal devices has been proposed by 01ark and Lagerwa.
It has been proposed (Japanese Unexamined Patent Publication No. 56-10721)
6, US Pat. No. 4,167,924, etc.).

As a liquid crystal having bistability, a strong n-type liquid crystal having a chiral smectic C phase (SmO*) is generally used. This liquid crystal has a bistable state consisting of a first optically stable state and a second optically stable state with respect to the trap, and therefore, unlike the optical modulation element used in the above-mentioned TI type liquid crystal, For example, the liquid crystal is oriented in a first optically stable state with respect to one electric field vector, and the liquid crystal is oriented in a second optically stable state with respect to the other electric field vector. In addition, this type of liquid crystal very quickly adopts one of the two stable states in response to the applied electric field number ζ, and
) It has the property of maintaining its state when no electric field is applied. By utilizing such properties, substantial improvements can be obtained in many of the problems of the conventional TN type device described above. This point will be explained in more detail below in connection with the present invention. However, in order for an optical modulation element using this bistable liquid crystal to exhibit predetermined driving characteristics, the liquid crystal placed between a pair of parallel substrates must be It is necessary that the molecules be in such a state that conversion between stable states can occur effectively. For example SmO* or 8mH*
For strongly electrostatic liquid crystals with phases, SmO* or E
A liquid crystal molecular layer having a 1m phase is perpendicular to the substrate surface,
Therefore, a region (monodomain) in which the liquid crystal molecular axes are arranged substantially parallel to the substrate surface tends to be formed. However, conventional optical modification using a liquid crystal with bistability 11
In the M1 device, the actual situation is that the arrangement of liquid crystals having such a monodomain structure was not always formed satisfactorily, and sufficient characteristics could not be obtained. For example, methods of applying a magnetic field, methods of applying shear force, etc. have been proposed in order to provide such an orientation state. However, none of these methods necessarily gave satisfactory results. for example,
The method of applying a magnetic field has the drawback that it requires large-scale equipment and is difficult to achieve at the same time as creating an fW layer cell with good operating characteristics; The problem is that it is incompatible with the injection method.

By the way, in the device using the TN type liquid crystal as mentioned above,
One way to form monodomains of liquid crystal molecules parallel to the substrate surface is to rub the substrate surface with something like cloth (
A rubbing method, a method of diagonally depositing 810, etc. are used.

For example, the liquid crystal in contact with the rubbed substrate surface 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 rubbed surface has the effect of preferentially arranging liquid crystal molecules in one direction. A structure with a plane to which this orientation effect is applied is, for example,
This is shown in Canadian Patent No. 1010156 by W. He1frlch and M.8chadt. Method #1 of forming an alignment effect by this rubbing method is to apply S10. A structure having a plane formed by oblique vapor deposition is used, and this plane having uniaxial anisotropy of 810 and 5iO7 has the effect of preferentially aligning liquid crystal molecules in one direction.

In this way, alignment control methods such as rubbing and oblique evaporation are one of the preferred methods for creating liquid crystal molecules, but these methods cannot be applied to liquid crystals that have bistability. When C orientation control is applied, a plane is formed that has a wall effect that preferentially orients the liquid crystal in only one direction.
It has the disadvantages of inhibiting bistability to electric fields, rapid response, and monodomain formation.

In view of the above-mentioned circumstances, the main object of the present invention is to provide a bistable device which has potential suitability as a display element with high-speed response, high density pixels and a large area, and an optical shutter with a relatively high shutter speed. To provide a liquid crystal orientation +11 control method that can fully exhibit its characteristics by improving the monodomain formation property or initial orientation property that was conventionally used in an optical modulator using a liquid crystal having properties. It is in.

As a result of further research for the above-mentioned purpose, the present inventors found that the liquid crystal material is particularly suitable for use in different phases (highly vortex-like ◇-- such as the 91-eha-tokichi phase), as well as for cy-axial anisotropy (e.g., 8 mA (sphmetic A), etc.). When we focused on the orientation in the temperature-decreasing process of transitioning to the low-temperature state of At the spatial phase interface with the uniaxially anisotropic phase region, the uniaxially anisotropic molecular axis that is newly generated through a phase transition is parallel to the orientation direction of the uniaxially anisotropic liquid crystal molecules that had already been formed. It was found that monodomain-axial anisotropy grows extremely stably when the direction of growth of the above-mentioned -axial anisotropic phase region and the alignment direction of liquid crystal molecules are orthogonal to each other. . Furthermore, by arranging a cylindrical member with horizontal alignment, the present inventors formed the initial uniaxially anisotropic nucleus as a monodomain uniaxial anisotropic phase in which liquid crystal molecules were aligned parallel to the cylindrical member. The present inventors have discovered that it is possible to obtain a liquid crystal element having a structure that allows both the operating characteristics of the element based on the bistability of the liquid crystal and the monodomain property of the liquid crystal layer.

The present invention is based on the above-mentioned knowledge, that is, the liquid crystal orientation control method according to the present invention has been made based on the above-mentioned knowledge. An axially anisotropic phase (smectic phase, nematic phase) is formed near the interface with the cylindrical member, and the -
The above-mentioned another phase near the phase interface formed between the chiku-tankichi phase and another phase on the high-temperature side of the dazzling phase (tokichi phase, nematic phase, cholesteric phase) is cooled down to form the chiku-kuchikichi phase. -! of liquid crystals aligned parallel to the liquid crystal alignment direction! A liquid crystal orientation control method for forming liquid crystal monodomains aligned in one direction by causing the anisotropic phase to become a phase transition and causing the phase transition to occur continuously from the phase interface in a direction perpendicular to the phase interface. It has the following characteristics.

Hereinafter, the present invention will be described in detail with reference to the drawings as required. ? , follow one rule.

Particularly suitable liquid crystal materials for use in the present invention are liquid crystals with bistability and ferroelectricity, specifically chiral smectate C phase (NmO
*) or a liquid crystal having an H phase (SmH'') can be used.

Regarding evaluation III of strong electroconductive liquid crystal, for example, "I,"
J! t JOURNAIJDJI! PHYEI Engineering GI
UJII Lle T11RI3”56 (L69) 1975
, [Ferroelectric Liquid
Crystals-J i' AppliecL Ph
ysics Letters” 36 (L-69)
1975゜[Ferroelectric Liquor
id Crystals-J; Applied Ph
ysics Letters"36(11)1980゜"Submicro Becon+l B15table
θBle(BtroopticSwitching i
Liquid crystals are described in ``Liquid Crystals'' in Solid State Physics 116 (141) 1981, and in the present invention, the highly electrostatic liquid crystals disclosed in these documents can be used.

Strong [Specific examples of conductive liquid crystal compounds include No. 1, Desyloxybenzylidene-P'-aminol-2-methylbutylcinname) (DOBAMBO), Hexyloxybenzylidene-p'-amino-2-chlorobutyrubincinname) (HOBACPC) ), 4-o-(2-methyl)-butyl resol cylidene-4'-octylaniline (MBR
A8) is mentioned.

When constructing an element using these materials, the element is supported by a copper block with a heater embedded, etc., as necessary, in order to maintain the temperature state such that the liquid crystal compound becomes the SmO'' phase or the smn* phase. be able to.

■Figure 1 shows the operating amount of the liquid crystal display, the light stop, and the cell 1'? It is a drawing of 11 to 1. 11 and 11' are In, 02. SnO2 or engineering To
This is a Jb plate (glass plate) coated with a transparent backing made of a thin film such as ndium-tin oxide, etc., and between which a liquid crystal molecular layer 12 is oriented perpendicular to the glass surface. ” , 17i liquid crystal has been introduced. 15 shown in the figure represents a liquid crystal molecule, and this liquid crystal molecule 13 is orthogonal to that molecule and has a dipole moment in the optical direction) (P) 14. It has a substrate 11.
When a voltage higher than a certain threshold is applied between @4@ on The orientation direction can be changed. 7j [Crystal molecule 15 has an elongated shape, and its length is 4111
Liquid crystal photogenesis exhibits refractive index anisotropy in one direction, and therefore, if one photon of crossed nicols is placed below and below the glass surface, the optical temporality changes depending on the voltage applied. It is easily understood that it becomes an element.

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 Part 2, and the dipole moment (PJ) is directed upward. (24) or downward (
It can be in one of 24 states. When an electric field E or E' with a different polarity above a certain threshold value is applied to such a cell by the voltage applying means 21 and 21' as shown in FIG. The liquid crystal molecules are oriented either upward 24 or downward 24' in response to the electric field vector, and accordingly the liquid crystal molecules are oriented either in the first stable state 23 or in the second stable state 23'.

As mentioned above, 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 explain the second point with reference to FIG. 2, for example, when an electric field E is applied, the liquid crystal molecules
This state is stable even when the electric field is turned off. When an electric field E' in the opposite direction is applied, the liquid crystal molecules are oriented in a second stable state of 1 m2 S' and change their orientation, but they remain in this state even after the electric field is turned off. Also, 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.

As mentioned earlier, the most time-consuming process when forming an element using a liquid crystal with such lyrical conductivity is 13m0.
It is difficult to form a highly monodomain cell in which a layer having a "phase or 8mH" is aligned perpendicular to the substrate surface and 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.

FIG. 3(A) is a partial plan view of an embodiment of a liquid crystal element obtained by the liquid crystal alignment control method of the present invention, and FIG. . Both figures are rounded to an accurate scale to make the cell structure easier to understand. In this example, a liquid crystal cell 100 shown in FIG. 3 shows a configuration example of a shutter array for a printer.
01' are held at a predetermined distance by a spacer (not shown), and the pair of substrates are bonded together with an adhesive 106. Furthermore, on the substrate 101, a plurality of transparent electrodes 102 are formed. The electrode group (for example, the electrode group for applying a scanning voltage in the matrix electrode structure) is formed in a predetermined number of turns, such as a strip pattern. On the substrate 101', there is an electrode group (for example, a signal voltage application electrode group in a matrix electrode structure) consisting of a plurality of transparent electrodes 102' intersecting with the transparent electrode 102 described above, as shown in the figure (107'). The transparent electrode 102 is formed with a segment pattern connected in a staggered manner.The transparent electrode 102 has a lead 107 and
The transparent electrodes 102' are connected to the leads 107'ifi, respectively, so that signals from an external circuit are connected to the leads 107' respectively.
and is input to the terminal 107'. Such substrates 101 and 101' can be made of, for example, -silicon oxide, silicon dioxide, monovalent aluminum.

Zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide, boron nitride, polyvinyl alcohol, polyimide, polyamideimide, holiesderimide, polyvaraxylerin,
Polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyamide, polystyrene, cellulose resin, melamine resin, urea resin and acrylic (?
An insulating film (not shown) patterned using i1 resin or the like can be provided. This disconnected line pi, da bo crystal layer 103
It also has the advantage of being able to prevent the generation of current caused by undesirable substances contained in minute quantities in the liquid crystal compound, and therefore does not deteriorate the liquid crystal compound even if the operation is repeated.

The cell structure of this concrete card 11 includes a liquid crystal M103 that exhibits a talking property at a predetermined temperature as described above, a cylindrical member 104, and a heating element 105 such as a heater.

As the cylindrical member 104, a good song I11 is used.
A glass fiber having a wall surface 104' is suitable, and as shown in FIG. I can do it.

The heating element 105 may be made of, for example, indium oxide, tin oxide, or Tα (Tin 0x1dθ). It is suitable to use a four-film resistor.

In this liquid crystal cell 100, photons 10B and 108' in a crossed Nicol state or a parallel Nicol state are arranged on both sides of substrates 101 and 101', respectively, and a voltage is applied between electrodes 102 and 102'. When applied, optical changes will occur.

To give a more specific example of the liquid crystal cell 100 shown in FIG.
Band-shaped scan with m! , an electrode group, and one transparent electrode 102
' forms one pixel, and the signal 1! of 62.5 μm x 62.5 pm is formed. It can be a polar group. Further, it is preferable that the heating element 105 is an ITO voice membrane having an average width of 0.6 mm and a thickness of 100 mm, and the liquid crystal layer 103 is maintained at a thickness of 2 μm.

Such a liquid crystal cell 1004, a heating case (not shown)
108 photons accommodated in the space and vertically orthogonal to each other,! :
Arrange 108' f? IL, this can be operated as a liquid crystal shutter array for an electrophotographic printer. In this case, the lost mark B in FIG. 3(A) is the rotational direction of the electrophotographic W optical drum.

Below, it is strong at the specified temperature! L'[Liquid crystal material showing characteristics DOB
AMBO(7):14, H is set to 1, -c, liquid crystal jH'4105L7) The alignment control method will be specifically explained using FIG. 283. First, 100 liquid crystal cells filled with DOBAMB (!) are set in a heating case (not shown) that heats the entire cell uniformly.Next, the average temperature of the cells is set to, for example, 90 Control the temperature of the heating case so that the

At this time, DOBAMBO is in the EImO'' phase or 13mA phase as a liquid crystal phase.Here, when a current is passed through the heating element (heater) 105 and the current value is gradually increased, the 5InA only in the vicinity →
The transition temperature of the isotropic phase, about 118 t'' is exceeded, and a phase transition occurs to an isotropic phase, that is, a liquid phase state.

As the current is further increased, the equi-lucky phase region expands while remaining substantially parallel to the heating element 105, and eventually the entire liquid crystal layer 103 becomes an equi-lucky phase.

In this state, the longitudinal direction of the liquid crystal cell 100 (FIG. 3(A)
) is uniform, and a temperature gradient is formed such that the temperature gradually increases from the cylindrical member 104 to the heating element 105 in the transverse direction (direction B of the third figure). . For example, O' of the cylindrical member 104
A temperature gradient is formed by setting the vicinity of the wall surface 104' to be, for example, about 120mm, and the vicinity of the heating element 105, which is about 1.5yxll, to be tf140t'.

Next, if the temperature of the case in which the cell 100 is set is controlled to be gradually lowered by 90 mm, for example at a rate of 10 mm/h, with the above-mentioned temperature gradient applied to the cell 100, First, in this @rJA, the temperature in the vicinity of the wall surface 104' of the cylindrical member 104 (I11) is lower than the transition temperature (approximately 116 mm) from the isokitic phase to the SmA phase. A nucleus is formed. At this time, the cylindrical member 104
The side camellia surface 104' and the surface 109 of the top plate 101 are (t''J
Both have the effect of aligning the liquid crystal molecules in the horizontal direction, so when the SmA phase is formed near the 91ij wall surface 104', the liquid crystal molecule axis is within the structure (109) of the substrate 101 and the cylindrical White side wall surface 1 of ff1f material 104
04' is subjected to a forcing force that produces an alignment parallel to the longitudinal direction, thus forming the SmA phase nucleus Virili1.
The wall surface 104' and the substrate 101 are oriented horizontally with respect to the substrate 109, forming a monodomain. Furthermore, when the temperature of the case is lowered, the iso-yoshitic phase near the phase interface I1 between the already formed 5rnA and the iso-yoshitic phase becomes compatible with SmA such that the direction is parallel to the arrangement direction of SmA near the phase interface. A transition occurs, and as a result, as the temperature continues to fall under the condensation gradient F'ii', the monodomain region of the 111 mA phase expands continuously. At this time, the growth rate of the phase interface between the monodomain region of the E1mA phase and the isotonic phase region is the same in the longitudinal direction of the liquid crystal cell 100 (in the direction of arrow C in FIG. 3A). Preferably, the case temperature is e.g.
When the temperature reaches such a level that almost the entire liquid crystal, except for the vicinity of the heating element 105, undergoes a phase transition to the SmA phase.

Next, when the current flowing through the heating element 105 is gradually lowered to eliminate the temperature gradient, the temperature of the liquid crystal cell 100 becomes uniform throughout the cell, and the liquid crystal undergoes a phase transition to the SmO'' phase. , the molecular arrangement of the liquid crystal near the heating element 105 may be in a random state, but %[j10
The region where 2 and 102' are formed is a uniform monodomain.

In the liquid crystal alignment method described above, it is important to note that it is desirable to provide as large a temperature gradient as possible in the B direction in Figure 3 (A), but in the C direction, it is desirable to have a uniform temperature be.

This point will be explained using FIGS. 4(A) to 4(D). That is, FIG. 94 (5) shows the growth process of the SmA phase region during the temperature decreasing process by slow cooling when the heating element 105 is formed into a band-like shape and the SmA phase is formed on this element by the method described above. is schematically shown.

In the figure, 201 is the SmA phase region 202 and the Tokichi phase region 205.
represents the phase interface of When the heating element 105 has a straight expansion shape with uniform width as shown in the figure, when the liquid crystal cell 100 is set in a case (not shown), the case! In a case where no special measures are taken, since the temperature is lower at the ends of the liquid crystal cell 100 in the longitudinal direction than at the center, the phase interface 201 is closer to the nucleation member 104 near the center.
#1 grows parallel to the side wall surface 104', but at its end E, it grows with a nod as shown in (b). The alignment state of liquid crystal molecules in the edge region and the center region shown in FIG. 4(A) are shown in FIG.
) and Figure 4 (0) shows 4% contract.

As shown in plCa diagram (B), S in the region of end E
The mA phase 202 indicates the liquid crystal molecule axis direction 202'. As can be seen from the figure, when the fl, lI wall surface 104' and the phase interface 201 are significantly tilted from the parallel state (#(
At an angle θ), the alignment direction of the liquid crystal molecules 202' is not parallel to the side wall surface 104', but is tilted by an angle θ2 (θ2=01). This is because when the E1mA phase grows near the phase interface 201, the liquid crystal molecules 20
2 is presumed to be because it tends to be oriented in a direction perpendicular to the growth direction of the 8 mA phase.

Furthermore, in a region where the inclination angle θ1 of the phase interface 201 changes rapidly, the liquid crystal molecules cannot align and are separated into different domains with greatly different alignment directions, resulting in the appearance of defect lines as shown in 204. . On the other hand, as shown in FIG. 4(0), the E1mA phase 202 in the central region (H
When the liquid crystal molecule axis direction 202' is substantially parallel to the IT wall surface 104' and the phase interface 201, the liquid crystal molecules are also parallel and a uniform monodomain 8 mA phase 202 is formed. Figure 4 (D) shows the shape of the heating element 105 that has been improved in view of the above points. As shown in the figure, by narrowing the width of the heater pattern at the end of the heating element 105,
By increasing the resistance value of the heating element at the end and increasing the amount of heat generated at the end, the temperature in the longitudinal direction of the liquid crystal cell 100 can be made uniform. Therefore, the phase interface 201 between the SmA phase 202 and the Tokichi phase 205 becomes parallel to the A011 phase 201, and a uniform monodomain is obtained as a whole.

Now, the alignment is completed through the steps described above, and even though the monodomains may appear to be uniformly completed, in reality, a voltage is applied between the electrodes 102-102' to form the liquid crystal. Switching as an optical modulation element (?!
When studying the J-characteristics, non-uniformity in optical contrast and response speed may occur depending on the region. This phenomenon is thought to be caused by structural distortion in the temperature gradient set during orientation. To prevent cracking, increase the temperature of the 5-layer case after the alignment process is completed, and make the liquid crystal Sm
By causing a single carrier phase transition from the C* phase to the f1mA phase, and then gradually lowering the temperature of the case to the f1 and ElmO'' states, it is effective to eliminate the above-mentioned strain due to structural relaxation.

FIG. 5 shows another example of a heating element for preventing the temperature at the ends of the liquid crystal cell 100 from becoming lower than that at the center during the formation of a temperature gradient during the alignment process. heating element 10
5. Heating element 3 that heats the edge of the liquid crystal display/I/100
By using 01 and 502, it is possible to correct the temperature modification at the end as described above. In this way, heating elements 105, 301 and 30 are placed around the liquid crystal cell 100.
2, a uniform monodomain of the SmA phase is formed.

FIG. 6 shows another embodiment based on the present invention, in which a heating element 105' is separately provided on the back side of the substrate 101. The heating element 105' heats the entire liquid crystal cell 100, and is used in common with the heating element 105, for example, when the alignment of the liquid crystal is disturbed due to some trouble when actually used as a liquid crystal optical modulation element. By doing so,
It is possible to carry out reorientation by performing a predetermined process.

That is, the entire liquid crystal cell 100 is heated by heating the SmO'' phase formed in the above-described manner with the heating element 105', and the whole liquid crystal cell 100 is heated by 8 m
It undergoes a phase transition to the A phase, and then is slowly cooled down to the 8 mO'' phase to form a uniform monodomain again. Of course, this heating element 105' can also be provided on the back side of the substrate 101'.

The liquid crystal cell 100 shown in FIG.
A specific example is shown in which a heating element 110 made of an alloy thin film is provided. The shape of this heating element 110 is preferably the shape shown in FIG. 4(D) or FIG. 5 described above.

In addition, 100 liquid crystal cells shown in FIG.
5 shows a specific example in which a model-like heating element 111 made of TTO or Ni-0r thin pancreas is provided with a slope in the roughness.

When a constant voltage is applied in the longitudinal direction of this liquid crystal cell 100 (perpendicular to the paper surface), 1111 Q of the nucleation member 104
A temperature gradient is formed in the vicinity of the % surface 104', such that the temperature increases in the vertical direction.

At this time, between the heating element 111 and the electrode 102, a 1cm organic P film such as polyimide or an inorganic insulating film 11 such as 5in2
It is desirable to provide 2.

After forming the liquid crystal element of the present invention, a spacer can be used to control the thickness of the liquid crystal layer to a predetermined value. FIG. 9 shows an example of the structure of a liquid crystal element of the present invention having such a spacer structure. That is, the liquid crystal element shown in FIG. 9 has an electrode 10 having a transparent conductive pattern.
A spacer member 115 is formed between a substrate 101 having a substrate 101 and a substrate 101' placed opposite to this substrate 101, and this allows the film thickness of the liquid crystal 105 placed between the substrates 101 and 101' to be It is possible to make the uniformity of φ formula stable. The spacer member 115 is obtained by applying an electrically insulating material to a predetermined thickness on one of the substrates, and then forming the spacer member 115 into the shape shown in the figure using a photolithography technique.

10 to JX12 show examples of driving the liquid crystal element of the present invention.

FIG. 10 is a schematic diagram of a cell 41 having a matrix electrode structure in which a ferroelectric liquid crystal compound is sandwiched between. 42
is a scanning TFt electrode group, and is a 45 signal electrode group. Figures 11 (,) and (b) #'i, the voltage @1 signal applied to the selected and scanned electrode 42 (Il), and the other scanning voltages jM (M unselected scan 'N, +5.)
42 (n) and shows the electrical signal given to the 6th and 1(n).
C) and ) are respectively selected signal electrodes 43 (F3)
The electric signal given to the signal electrode 43 (n
) represents the number given to 1. Figure 11(a)
In ~(d), the horizontal axis represents time, and Kasuri Shikari I represents voltage. For example, when displaying a moving image, the scanning electrode group 42 is sequentially and periodically selected. Now, if the threshold voltage is Vthl to give the first stable state of a liquid crystal cell with bistable property, and the threshold voltage is -vth2 to give the second stable state, then the selected running current r Wind air given to Kanogoku 42 (b) (FV is,
As shown in (a), the phase (time) 1+
In the phase (time) t2, Hv is the alternating pressure, which becomes one in the phase (time) t2. In addition, other 7t'-plate electrodes 4
2(n) is in a grounded state as shown in FIG. 11(b), and is an electrical signal O. Meanwhile, the selected signal %
is applied to the pole 43(s), the signal is as shown in Fig. 11(c).
) as shown in v, and the unselected signal Mt
The electric phrase signal given to 4fh43 (b) is -V as shown in FIG.
N' th+ < 27 and -V) -V th2 >-
27 is set to the desired value. City like this:
The voltage waveform applied to each pixel when the tremor signal is strengthened is shown in Figure 12.?A12 Figures (a) to (d) are
They respectively correspond to pixels A, B, (3 and D in FIG.
A voltage of 2v exceeding the threshold value vth is applied to the pixel A on the selected rectangular band at phase t2. In addition, for pixel B existing on the same scanning line, the threshold value -v is reached at phase t1.
A voltage of -2v that increases th2 is applied. Therefore, depending on whether the signal kick electrode is selected or not in the selected scanning voltage, if it is selected, the liquid crystal molecules align to the stable state of M1, 5, if not selected, 4T2 Align the orientation to a stable state. In any case, the antecedent history of each pixel is
It has nothing to do with it.

On the other hand, as shown by pixels C and D, on the unselected scan line, all pixels C,! : The voltage applied to D is +V or -V, neither of which exceeds the M value voltage.

Therefore, the liquid crystal molecules in each of the images 1c and 1D maintain the orientation corresponding to the signal state when scanned last time without changing the arrangement state. That is, when a scanning electrode is selected, one line of signals is written, and until the next frame is selected,
This state (No. 8) can be maintained. Therefore, even if the number of scanning electrodes increases.

The illustrative duty ratio remains the same, and there is no reduction in contrast, no crosstalk, etc. At this time, the value of the voltage value V and the value of the phase (t1+t2) == T depend on the liquid crystal material used and the thickness of the cell, but it is usually 0.1 μsec to 2 m at 3 volts to 70 volts. s
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 (assumed to be a "bright" state when converted to an optical signal) to a second stable state (assumed to be a "dark" state when converted to an optical signal), and vice versa. I can wake up.

[Brief explanation of the drawing]

1 and 2 are perspective views showing a liquid crystal cell used in the present invention. Figure 3 (the slope is a plan view of the liquid crystal element used in the present invention, and Figure 3 (B) is its A-A' cross-sectional view. Figure 4 (A), Figure 4 ([3) and Figure 4 (0
) is a plan view schematically showing the growth process of liquid crystal. FIG. 4(D) is a plan view showing another embodiment of the liquid crystal cell used in the present invention. FIG. 5 is a plan view showing another embodiment of the liquid crystal cell used in the present invention. 6, 7, 8, and 9 are cross-sectional views showing preferred embodiments of the liquid crystal cell of the present invention. FIG. 10 is a plan view schematically showing the electrode structure of the optical modulation element used in the present invention. FIGS. 11(a) to 11(d) are explanatory diagrams showing signals for driving the optical modulation element of the present invention. Figure 12(a)~
(d) is an explanatory diagram showing a voltage waveform applied to each pixel. ioo...Liquid crystal cell 101.101'...Substrate 102.102'...Electronic (i 103...Liquid crystal layer 104...Nucle generation member 104'..., White side wall surface of the nucleation member 105.105
', 5 [11, 302, 110, 111... heating element 1
06...Glue agent 107.107', 107'...Lead bond 108.108'...Polarizer 109...Surface 112 of substrate 101...Edge supply film 113...Spacer Element! 4 Figure (C) ”@41:7] (D) (bn (d) (b) (d)

Claims (1)

[Scope of Claims] (i) First, a uniaxial heterophoric phase of liquid crystal aligned in one direction is formed near the interface with the cylindrical member between a pair of main plates,
Formed between the -off-axis phase and another phase at a high temperature (1; 1), the another phase near the nine-phase interface is cooled down to
By causing a phase transition between the liquid crystal alignment direction of the off-axis auspicious phase and the 1h anisotropic phase of the liquid crystal aligned in the axial direction, and causing the phase transition to occur continuously from the phase interface to the perpendicular direction, unidirectional A method for controlling the alignment of liquid crystals, characterized by forming monodomains of liquid crystals arranged in the same direction. (2) The liquid crystal orientation control method according to claim 1, wherein the phase interface has direct swelling property. (5) A patent in which the phase transition is a phase transition that occurs by lowering the temperature of the other phase, which has a temperature gradient in which the vertical side is lowered to a higher temperature than near the interface with the cylindrical member, under such a temperature gradient. A method for controlling alignment of liquid crystals according to claim 1. (4) The method for controlling the alignment of liquid crystals according to claim 1, wherein the liquid crystals aligned in one direction have a smectic physiognomy. (5) Claim 4 in which the temperature of the smectic human phase is lowered and a phase transition occurs to the smectic 0 phase or H phase.
Liquid crystal orientation control method described in Section 1. (6) The liquid crystal orientation control method according to claim 5, wherein the smectic C phase and R phase are chiral smectic 0 phase or H phase. (7) The liquid crystal orientation control method according to claim 6, wherein the chiral smect C phase and H phase are arranged in a non-helical structure. (8) The liquid crystal alignment control method according to claim 1, wherein the other phase on the high side of the -axis off-axis auspicious phase is a nematic phase, a cholesteric phase, or an equimyotic phase. (9) The liquid crystal orientation control method according to claim 1, wherein the cylindrical member and the substrate have the effect of aligning the liquid crystal in a horizontal direction. (10) A method for controlling the alignment of a liquid crystal according to Claim No. iJ#I, wherein the cylindrical member is a glass fiber. Liquid crystal alignment control method according to item 1. (12) Liquid crystal alignment control patented in that it has a cell structure including a cylindrical member between a pair of substrates and a heating element disposed at a predetermined distance from the cylindrical member. (15) A liquid crystal orientation control rod according to claim 12, wherein the cylindrical member is made of glass fiber. (14) A patent claim in which the cylindrical member is arranged in several pieces. (15) The liquid crystal alignment control element according to claim 12, wherein the heating element is a resistance heating element. (16) The liquid crystal alignment control element according to claim 12, wherein the heating element is a thin film resistance heating element. (17) The liquid crystal alignment control element according to claim 16, wherein the thin film resistance heating element is a heating element having a band-like shape. (18) A liquid crystal alignment control element according to claim 17, wherein the thin film resistance heating element having a band-like shape is a heating element that generates a larger amount of heat near its center and near its ends. (19) A liquid crystal alignment control element according to claim 17, wherein the thin film resistance heating element having a band-like shape has a central portion that is wider than its end portions. (20) A liquid crystal alignment control element according to claim 16, wherein the thin film resistance heating element is a heating element having a band-like shape formed around the substrate. (21) A liquid crystal alignment control element according to claim 12, wherein the -axis-transverse auspicious phase is a smectic phase. (22) A liquid crystal alignment control element according to claim 21, wherein the smectic phase is a smectic human phase. (23) A conductive If film serving as an electrode is provided on opposing surfaces of the pair of substrates.
A liquid crystal alignment control element described in LJi. (24) 1 having a cell structure with a cylindrical section and a planar heating element between a pair of substrates;
I'm heading to the nightclub! IIIf111 atmosphere. (25) The liquid crystal orientation 1HIJ cape element according to claim 24, wherein the cylindrical member is made of glass fiber. (26) A liquid crystal alignment control element according to claim 24, wherein a plurality of the cylindrical members b are arranged. (27) A patent claim in which the planar heating element is a resistance heating element. range i: the liquid crystal alignment control element according to item 4124. (28) Feature 4', wherein the planar heating element is a thin film resistance heating element.
F Claim 51 The liquid crystal alignment control element according to claim 24. (29) A liquid crystal alignment control element according to claim 28, wherein the thin film resistance heating element is a wedge-shaped heating element. (30) The liquid crystal alignment control rod according to claim 24, wherein the -axial phase is a smectic phase. (31) The liquid crystal alignment control rod according to claim 30, wherein the smectic phase is a smectic human phase. (32) A liquid crystal alignment control element according to claim 24, wherein a conductive thin film serving as one pole of bacteria is provided on the opposing J()In of the pair of substrates. (35) A cell structure comprising a cylindrical member and a compound that exhibits a uniaxial outside phase at a predetermined temperature between a pair of substrates, and a phase transition of the compound that exhibits a uniaxial outside phase at the predetermined temperature to a phase on the higher temperature side than the uniaxial outside phase. means for imparting a temperature gradient to the high-temperature side phase from the cylindrical member in the direction perpendicular to the cylindrical member; and temperature-lowering means for causing a phase transition of the high-temperature side phase to a uniaxial outer phase under a gradient of #, m degrees. OfL
A liquid crystal alignment control device. (54) The liquid crystal arranged in one direction is smectic A.
A liquid crystal alignment control device according to claim I, which is a phase-based patent. (35) The liquid crystal alignment control device according to claim 34, wherein the temperature of the smectic human phase is lowered to cause a phase transition from the smectic O phase to the H phase. (36) The liquid crystal alignment control device according to claim 65, wherein the smectic C phase or the j-or H phase is a chiral smectic at[J-stratified H phase. (37) The liquid crystal alignment control device according to claim vJI, paragraph 36, wherein the chiral smectate C phase or H phase is arranged in a non-helical structure. (3B) The liquid crystal orientation control device according to claim 33, wherein the other phase on the high temperature side of the -+mm anisotropy is a nematic phase, a cholesteric phase, or an isotonic phase.