Method of forming alignment film for liquid crystal display cell

A liquid crystal display cell being capable of display with liquid crystal molecules aligned towards a predetermined direction has its display characteristics made greatly dependent on the properties of an alignment film coming into contact with the molecules of the liquid crystal. A louver having a predetermined angle is disposed between the substrate on which the alignment film is to be formed and an evaporation material source to pass a material evaporated from the evaporation material for deposition onto the substrate. The thus formed film exhibits a very great orientation controlling power of biaxial anisotropy. This forming method of the alignment film also allows the easy formation of the alignment film on a large substrate.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a forming method of an alignment film for 
a liquid crystal display cell, which employs liquid crystals, for example, 
of smectic and nematic phases and effects display in response to a 
variation in orientation of their molecules. 
2. Description of the Prior Art 
An alignment contacts with molecules of a liquid crystal and serves to 
direct the arrangement of the liquid crystal molecules in a predetermined 
direction. For this purpose, a film has conventionally been utilized which 
is provided at its surface with a plurality of grooves arranged in a 
predetermined direction. Its particular manufacturing method is described 
in "SID International Symposium Digest of Technical Papers", P. 100 
(1972). The groove can be made first by forming a substrate with an 
organic film at its surface and then by rubbing the surface of its film. 
The alignment film manufactured by the rubbing method has the drawback 
that its contact with a liquid crystal material for a long time causes a 
structure at its intersurface to be changed gradually with the result of 
irregularity in the orientation of the liquid crystal because the 
alignment film employs the organic film. 
U.S. Pat. No. 3,834,792 of J. L. Jannig (Alignment film for a liquid 
crystal display cell) discloses a technique in which the alignment is 
formed by using an inorganic evaporation film instead of using the organic 
film. In this method, the substrate is so disposed in a vacuum evaporation 
container that its surface may be disposed at a low angle relative to an 
evaporation source to cause corpuscles flying downwardly from a 
predetermined oblique direction to be deposited on the surface of the 
substrate. The alignment film formed by the oblique vacuum evaporation 
method provides uniaxial anisotropy relative to the direction of the 
evaporation source and thus orients the liquid crystal molecules. 
In the above-mentioned method, the evaporation source must be disposed in a 
very limited positional relation to the substrate in order to ensure a 
uniform orientation. Assuming, for example, that a distance from the 
evaporation source supposed to be a point to the substrate is 50 cm and an 
angle of evaporation for the oblique evaporation film is desired to be set 
in the tolerable range of 68 .+-. 2.degree. in the oblique evaporation 
method, the substrate must be below about 40 mm in diameter in the 
direction of evaporation source. If the substrate is above 40 mm in 
diameter, then the angle of evaporation amounts at both its ends to more 
than 4.degree.. This results in formation of no uniform orientation and in 
defective display. 
The alignment film formed by the oblique vacuum evaporation method provides 
uniaxial anisotropy only in the direction of evaporation source, so that 
it does not exhibit sufficiently great orientation controlling power for 
the liquid crystal. For, for example, a liquid crystal with a shiff base 
##STR1## 
exhibiting an excellent orientation at its interface, the film exhibits 
good controlling ability, but for a liquid crystal with an azoxy base 
##STR2## 
having a great response when used as a display cell, it exhibits no 
orientation controlling characteristics. In the chemical expression, R and 
R' show an alkyl group. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a new method for forming 
an alignment film which comes into contact with a liquid crystal and 
orients the molecules of the liquid crystal strongly in a predetermined 
direction. 
Another object of the present invention is to provide a method for forming 
an alignment film which comprises a deposited film covered with very fine 
projections, the surface of the film having at least biaxial anisotropy. 
A further object of the present invention is to provide a method for 
manufacturing an alignment film exhibiting a uniform orientation over a 
wide area with high yield. 
A still further object of the present invention is to provide a method for 
forming an alignment film for a twisted liquid crystal. 
In order to achieve the above-mentioned objects, the alignment film is 
formed by the following means in accordance with the present invention. A 
substrate on the surface of which an alignment film is to be formed is 
disposed in a vacuum container together with an evaporation material 
source in an opposed relationship therewith. 
A louver comprising a plurality of leaves with a predetermined angle of 
inclination is disposed between the substrate and the evaporation material 
source to pass evapoated particles through the gaps o the louver to the 
substrate. The determination of the pattern of the louver and the setting 
of a vacuum pressure to a predetermined value make it possible to form the 
alignment film for a liquid crystal having biaxial anisotopy.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A substrate on which an alignment film is formed is made of transparent 
glass, plastics or the like and has an electrode disposed at its one 
surface as required to supply liquid crystal molecules with a signal. If 
the electrode is provided, it is covered at its surface with another 
alignment film. It is, on the other hand, also possible to cause the 
electrode itself to serve as the alignment film. 
The substrate is disposed in a vacuum container in such a manner that its 
one surface on which the alignment film is to be formed opposes an 
evaporation source. The pressure within the container is reduced so that 
evaporated particles from the evaporation source reach the surface of the 
substrate. The degree of pressure reduction is so selected that the 
evaporated particles have a suitable mean free path. More specifically, 
the evaporation is carried out at vacuum pressures of 1 .times. 10.sup.-2 
to 5 .times. 10.sup.-5 mmHg. The pressure less than 5 .times. 10.sup.-5 
mmHg leads to too elongated linear flying distance of the evaporated 
particles with the result of the remarkably reduced number of particles 
capable of reaching the surface of the substrate due to the obstruction in 
the presence of the louver. The pressure higher than 1 .times. 10.sup.-2 
mmHg, on the other hand, undesirably degradates the adhesion of the 
deposited film. FIG. 1 shows the results of the collision distance of the 
evaporated particles at pressures of 10.sup.-2 to 10.sup.-5 mmHg. In the 
graph, a curve c is obtained at 10.sup.-2 torr, a curve d at 10.sup.-3 
torr, a curve e at 10.sup.-4 torr and a curve f at 10.sup.-5 torr. In the 
figure, the mean free path denotes a collision distance of the evaporated 
particles which amount to 60%. The atmospheric pressure suitable from the 
view-point of forming an alignment film of biaxial anisotropy is such a 
pressure at which the mean free path amounts to 2 to 50 cm. The pressure 
at which it amounts to 5 to 20 cm is most suitable from the view-points of 
operations and stability in quality of the film. The mean free path longer 
than 100 cm results in the formation of the liquid crystal with only 
uniaxial aniostropy with the orientation power of its molecules remarkably 
reduced, so that no alignment film that is intended according to the 
present invention is formed. It should be noted that the distance between 
the evaporation source and the surface of the substrate must be longer 
than the mean free path. A method for heating the evaporation source with 
a heater, or a method of emitting an electron beam or ion beam to 
evaporate the material of evaporation source is introduced to fly the 
particles from the evaporation source in the vacuum. One feature of the 
present invention is the ability of forming the alignment film by the use 
of a chemical vapor deposition method. 
In the present invention, these methods are used to fly the particles in a 
random direction at reduced pressures in the vacuum container, some of the 
particles which have a desired angle of incidence relative to the 
substrate being selected fro irradiation to the substrate. 
In the present invention, the angle of incidence of the particle is an 
angle measured from a normal (perpendicular plane) on the surface of the 
substrate. 
The substrate of the evaporation source from which the alignment film is 
formed is non-metallic compounds such as silicon monooxide, silicon 
dioxide, calcium fluoride, magnesium fluoride, lithium fluoride, cerium 
fluoride, boron nitride, or metals and metallic compounds such as gold, 
chrome, titanium, titanium oxide, aluminum oxide, indium oxide, tin oxide, 
tungsten oxide, cerium oxide, lead fluoride, cadmium sulfide, lead 
sulfide, zinc sulfide, antimony sulfide, etc. There is a danger of causing 
an undesired reaction in response to the displacement of impurities in the 
liquid crystal to the interface of the electrode in the case where the 
liquid crystal display cell is used for a long time. When such a danger 
arises, an insulating alignment film is advantageously selected. For an 
alignment film which serves simultaneously as the electrode, indium oxide, 
tin oxide or the like is employed. 
The fine model structure of the alignment film formed by the present 
invention is supposed as being shown in FIG. 2a. In other words, the 
particles in a direction of arrow are so deposited as to form one gently 
inclined surface, which intersects with two surfaces with a large angle of 
inclination with two edges defined. The anisotropy of the film is produced 
in the direction of these edges. On the other hand, the film formed by the 
vacuum oblique evaporation is considered as being in the form of steps as 
shown in FIG. 2b and exhibits the anisotropy along an edge intersecting at 
right angle with the intruding direction of the evaporated particles. It 
should be noted that the molecules of the liquid crystal are aligned in a 
direction of resultant vector of the anisotropies of the film. 
The conditions under which the deposition as shown in FIG. 2a according to 
the present invention is formed should be such that most of the flying 
particles have angles of incidence ranging from 45.degree. to 75.degree. 
and some flying particles coexist therewith which have angles of 
inclination deviated by 10.degree. to 60.degree. including a primary angle 
of inclination. 
A louver used to deposit on the surface of the substrate the evaporated 
particles having a predetermined angle of incidence as mentioned above 
basically includes a pattern and a positional relation relative to the 
surface of the substrate as shown in FIG. 3. Assume that d.sub.o is a 
distance of the substrate 33 from leaves 34 constituting the louver, l a 
width of the leaf, t its thickness, .theta. an angle of inclination of the 
leaf 34 relative to the surface of the substrate, .alpha. and .beta. 
minimum and maximum angles of inclination defined by two adjacent leaves, 
and d.sub.1 an interval between the leaves. These values may be determined 
experimentally for optimum conditions on the basis of the following 
teaching. 
The evaporated particles departing from the evaporation source collide with 
vapor molecules or with each other with the result of formation of 
variously directed groups of particles, which reach the entrance of the 
louver. The evaporated particles in some direction of component collide 
with the surface of the leaves and are interrupted as they pass through 
the louver. Thus, the particles having particular components are permitted 
to reach the surface of the substrate. The scattering of the particles at 
a time during which they pass through the louver results in weakened 
anisotropy of the film. As is apparent from FIG. 3, the particles which 
intrude to the substrate at an angle of .alpha. from the end of the leaf 
on the side of the evaporation source in the cross section of the louver 
have the longest flying distance, which is defined as being shorter than 
the mean free path. In other words, the shortest linear distance in a free 
space from the entrance of the louver to the surface of the substrate is 
always shorter than the mean free path of the evaporated particles. The 
relation between the mean free path (m.f.p.) and the louver is expressed 
by the following equation: 
##EQU1## 
The too short interval d.sub.o from the surface of the substrate to the 
louver causes the shadow of the leaves themselves to be projected on the 
surface of the substrate with the result that the substrate has no 
evaporation film formed at some positions of its surface. The interval 
d.sub.o is, therefore, given by the following expression: 
##EQU2## 
On the assumption of an angle .delta. of incidence of the evaporated 
particles relative to the substrate, the relation between the angle of 
incidence and .alpha., .beta. is such as .alpha. &lt; (90 - .delta.) 
.apprxeq. .theta. &lt; .beta., where .alpha. and .beta. are as follows: 
##EQU3## 
Therefore, the narrowing of the interval between the leaves by 
##EQU4## 
or the widening of the width of leaf by 
##EQU5## 
cause both .alpha. and .beta. to come near to .theta., so that the 
difference between the maximum and minimum angles of incidence of the 
particles is made small. These conditions are shown in FIG. 4. 
.alpha..sub.1 and .beta..sub.1 are, respectively, the minimum and maximum 
angles of incidence when the thickness t of the leaf is 0.3 mm, the 
interval d.sub.1 between the leaves is 15 mm and the width l of the leaf 
is 20 mm. The widened width l of the leaf to 40 mm allows the particles 
having angles of incidence between curves .alpha..sub.2 and .beta..sub.2 
to reach the surface of the substrate. 
The more number of particles are incident on the surface of the substrate 
at right angle therewith, the more reduced biaxial anisotropy appears in 
the formed alignment film. The pattern of the louver is, therefore, so 
determined that the angle .beta. is below 90.degree.. 
The difference between the angles .alpha. and .beta. (angle of view) below 
10.degree. results in the formation of a film whose properties are 
substantially the same as those formed by the vacuum oblique evaporation 
method with insufficient orientation controlling power. The angle of view 
above 60.degree., on the other hand, causes the formation of spot-like 
discontinuous orientation lines, called domains, when the film is mounted 
on the liquid crystal display cell. For this reason, the difference 
between the minimum and maximum angles .alpha., .beta. of incidence 
defined by two adjacent leaves should be between 10.degree. to 60.degree.. 
These domains are also easy to appear in such a case where the evaporation 
source is disposed on a normal line of the surface of the substrate, but 
disappear when the evaporation source is several degrees away from the 
normal. The minimum interval d.sub.1 between the adjacent leaves is 
suitably on the order of 0.5 mm added to the leaf cross section (t/sin 
.theta.) from the viewpoint of formation of the film. 
The angle .delta. of incidence of the particles relative to the substrate 
depends substantially upon the angle .theta. of inclination of the leaf. 
Since the angle of incidence is 45.degree. to 75.degree. as mentioned 
above, the angle .theta. of inclination of the leaf substantially ranges 
45.degree. to 15.degree.. 
There is no particular limitation of materials constituting the louver; for 
example, such materials as metals, plastics, paper, ceramics or the like 
can be used, which generate no harmful gas at the time of evaporation and 
have resistance against a present temperature. 
The formed alignment film is 50 to 600 A thick. The thinner film results in 
the exposure of portion of the substrate with poorer orientation of the 
liquid crystal while the thicker film also degrades the orientation 
because the aligned projections of the alignment film are destroyed. The 
film is preferably 200 = 50 A thick. 
The detailed examination along a line parallel to the leaf about properties 
of the biaxial anisotropy in the film formed according to the present 
invention shows that there is a difference between angles of orientation, 
at which the liquid crystal is oriented, on a portion near to the normal 
from the evaporation source and on a portion spaced far away from it. It 
is further of course that the deposited film is thinner as it is farther 
away from the evaporation source. 
The angle of orientation of the liquid crystal varies substantially 
linearly on the line parallel to the leaf as shown in FIG. 5. In this 
figure, the angle .gamma. of orientation is shown as being measured from 
an axis (y'-y) in a plane (x-x') - (y-y') in FIG. 6. 
Such a variation in angle of orientation on the axis (y-y') of the 
alignment film can advantageously be cancelled in the liquid crystal 
display cell in combination with a set of alignment films having the same 
properties. There is, however, a liquid crystal display cell in which a 
large sheet of alignment film is divided into small units, which are 
paired for display. For such a display cell, the units whose angle .gamma. 
of orientation is greatly different from each other are sometimes made 
paired and generate the irregularity of the characteristics. 
In this respect, screen plates (hereinafter referred to as lateral lattice 
66) are provided which intersect with each leaf 64 of the louver at right 
angles as shown in FIG. 6. This makes it possible to reduce the change in 
angle of orientation on the axis (y-y') as mentioned above. The lateral 
lattice may be provided between the louver and the evaporation source 65, 
beteen the lourver and the surface of the substrate, or within the louver. 
Particularly, the combination of the louver and the lateral lattice made 
integral therewith provides an oblique lattice or hive-like louver and 
increases a mechanical strength. FIG. 5 shows curves obtained by the 
measurement of the angle of orientation on the axis (y'-y) versus a ratio 
w.sub.a /l.sub.a of the lattice width w.sub.a to the lattice interval 
l.sub.a of the lateral lattice 66. In the figure, l.sub.o represents no 
lateral lattice, l.sub.2 the lattice of w.sub.1 /l.sub.a = 2, l.sub.3 the 
lattice of w.sub.a /l.sub.a = 3 and l.sub.4 the lattice of w.sub.a 
/l.sub.a = 4. The lateral lattice having a ratio w/l of 1 to 5 is 
effectively provided. 
The widening of the lattice interval at positions spaced farther away from 
the evaporation source or the widening of the lattice width at positions 
nearer to the evaporation source leads to the uniformed deposition on the 
axis (y'-y). FIG. 7 shows a deposition method using the lateral lattice 
for keeping the deposition uniform on the axis (y'-y). In the figure, 
evaporated particles departing from an evaporation source 75 pass through 
a lateral lattice 76 and a louver 74 to a substrate 73. In this figure, 
the evaporated particles are shown as travelling straight in order to show 
the constant evaporation. Actually, however, the travel of the particles 
so deviates that they may be not interrupted by the lateral lattice. As a 
result, the surfactant is by no means discontinuous. 
EMBODIMENT 1 
A substrate 83 of glass (2.5 mm thick, 50 mm long and 40 mm wide) formed 
thereon with a transparent conductive film of In.sub.2 O.sub.3 by 
evaporation was washed at its surface with trichloroethylene and acetone 
to remove therefrom fat and dust and then disposed in a vacuum evaporation 
container (bell jar) 82 as shown in FIG. 8, and SiO was evaporated at an 
air pressure of 5 .times. 10.sup.-4 torr. Powders 85 of SiO was contained 
in a crucible of tantalum and heated by a spiral heater made of tungsten 
for evaporation. The distance between the evaporation source 85 and a 
louver 84 was 40 cm, and the distance d.sub.o between the louver 84 and 
the glass substrate 83 was 12 mm. Leaves constituting the louver were made 
of stainless steel plates each 0.5 mm thick and 20 mm wide with the leaf 
angle .theta. of 15.degree. and leaf interval of 15 mm. In this example, 
.alpha. is 9.degree. and .beta. is 42.degree.. The detailed arrangement of 
the substrate in FIG. 8 is illustrated in FIG. 9, in which there are shown 
a substrate 93, louver 94 and evaporation source 95. 
Two glass substrates evaporated with SiO by the above-mentioned method were 
arranged with their surfaces made inside on which the evaporation film of 
SiO was formed and with a right-angled direction of evaporation (direction 
x'-x) shown by arrows in FIG. 7 to provide a liquid crystal cell in 
combination with a spacer of 9 .mu. thick polyethylene terephthalate film. 
The cell was sealed on its periphery with an adhesive (epoxy resin; 
Epotic, brand name of Epoxy Technology Incorporated). The liquid crystal 
injected to the cell was made of compounds of shiff base of propyl 
benzylidene cyano aniline and hexyl benzylidene cyano aniline. The 
injection was carried out within the vacuum bell jar in such a manner that 
the liquid crystal was heated to an isotropic state by means of an 
infrared lamp. After the injection, the liquid crystal was gradually 
cooled back to a liquid crystal state. 
In order to observe the optical state of the above-mentioned liquid crystal 
cell, a polarizer and an analyzer are disposed before and behind the 
liquid crystal cell, respectively. The polarizer had its polarization 
direction arranged substantially at right angle with that of the analyzer, 
and substantially in an alignment with the evaporation direction on the 
substrate of the liquid crystal cell on the side of the polarizer. In this 
state, the liquid crystal cell was viewed to be uniformly bright from the 
side of the analyzer under light from a parallel white light source 
disposed on the side of the polarizer. The liquid crystal cell was, on the 
other hand, viewed to be uniformly dark under the above-mentioned 
conditions with the exception of the polarization direction of the 
analyzer, which was arranged to be substantially parallel to the 
polarization direction of the polarizer. It is because the emitted light 
is polarized by the polarizer and twisted 90.degree. in polarization plane 
by the liquid crystal while it passes through the liquid crystal with the 
light being permitted to pass when its angle of polarization coincides 
with the polarization direction of the analyzer and with the light being 
interrupted when they are crossed. 
A rectangular AC voltage of 1 KHz was next applied across the two 
transparent conductive films respectively formed on the two sheets of 
substrate of the liquid crystal cell in order to measure the transmission 
of white light from a tungsten lamp at a temperature of 25.degree. C by 
means of a photomultiplier tube and an X-Y recorder. These results are 
shown in FIG. 10. As is apparent from the figure, the liquid crystal cell 
exhibits excellent characteristics with a threshold voltage of about 3 V, 
a voltage of about 5 V at which the transmission of light is saturated and 
the contrast of 180. 
EMBODIMENT 2 
A glass substrate formed with a transparent electrode was disposed in the 
vacuum evaporation container in a similar manner to that in the EMBODIMENT 
1, and SiO was evaporated at nitrogen pressures of 10.sup.-2 to 10.sup.-6 
Torr for 5 to 10 minutes. The thickness of the deposited film was measured 
by a surface roughness meter to measure the growth speed of the film, the 
results of which are shown in FIG. 11. As is apparent from the figure, the 
alignment film is grown due to the obstruction of the lourver so slowly at 
vacuum pressures below 10.sup.-5 Torr that it can be not formed. The 
alignment film of SiO 10 to 1000 A thick was formed according to the 
above-mentioned method, and a liquid crystal cell was constructed with the 
two films whose direction of evaporation is substantially perpendicular to 
each other in a manner similar to that as mentioned in Embodiment 1. The 
same liquid crystal as that in Embodiment 1 was filled in a similar 
manner. 
The liquid crystal cell was disposed between the polarizer and analyzer in 
the same manner as that of Embodiment 1 to measure the transmissions of 
light by the photomultiplier when the polarization direction of the 
analyzer is substantially orthogonal and parallel to that of the polarizer 
and to derive therefrom a ratio of the transmissions of light. The liquid 
crystal was further viewed by means of an orthogonal Nicol under a 
polarization microscope. The results are shown in Table 1. 
TABLE 1 
______________________________________ 
Ratio of 
Vacuum Thickness of 
Transmissions 
State of 
No. Pressure Film of light Orientation 
______________________________________ 
1 10.sup.-6 &lt;10 .about.20 Random 
2 10.sup.-5 &lt;10 .about.20 " 
3 5 .times. 10.sup.-5 
60 80 TN orientation 
4 10.sup.-4 80 100 " 
5 5 .times. 10.sup.-4 
80 100 " 
6 5 .times. 10.sup.-4 
100 180 " 
7 5 .times. 10.sup.-4 
200 190 " 
8 5 .times. 10.sup.-4 
400 180 " 
9 5 .times. 10.sup.-4 
600 80 " 
10 5 .times. 10.sup.-4 
1000 0 Longitudinal 
orientation 
11 10.sup.-3 200 190 TN orientation 
12 10.sup.-3 1000 0 Longitudinal 
orientation 
13 2 .times. 10.sup.-2 
100 180 TN orientation 
14 10.sup.-2 50 80 " 
15 10.sup.-2 100 100 " 
______________________________________ 
TN (orientation): Twist-Nematic 
EMBODIMENT 3 
A glass plate formed with a transparent electrode was disposed within the 
vacuum evaporation container similarly as in Embodiment 1, and SiO was 
evaporated at vacuum pressures below 5 .times. 10.sup.-4 Torr for ten 
minutes. The alignment film of SiO 400 A thick was formed according to the 
above-mentioned method, and the liquid crystal cell was constructed so 
that the directions of evaporation may be substantially orthogonal to each 
other in a manner similar to that as mentioned in Embodiment 1. The used 
liquid crystal contains a mixture having any ratio of composition of A 
(azoxy base) and B (shiff base) in combination with 5 to 10 by weight % of 
C (p-type additive). This is shown in Table 2. 
The liquid crystal cell was disposed between the polarizer and analyzer in 
the same manner as that in Embodiment 1 to measure the transmissions of 
light by the photomultiplier when the polarization direction of the 
analyzer is substantially orthogonal and parallel to that of the polarizer 
and to derive therefrom a ratio of the transmissions of light. The liquid 
crystal was further viewed by means of an orthogonal Nicol under a 
polarizing microscope. The results are shown in Table 3. 
Table 4 shows the results of measurement for reference in which a mixed 
liquid crystal of 100 portions of azoxy base and 30 portions of shiff base 
was sealed using alignment films formed at angles of evaporation of 
60.degree. to 82.degree. by the conventional vacuum evaporation method. 
The direction of orientation was longitudinal with no display signals 
obtained. 
TABLE 2 
______________________________________ 
Com- 
Liquid po- 
Crystal Components sition 
______________________________________ 
##STR3## 40 % 
A (Azoxy base) 
##STR4## 60 % 
______________________________________ 
##STR5## 33.3 % 
B (Shiff base) 
##STR6## 33.3 % 
##STR7## 33.4 % 
______________________________________ 
##STR8## 
C (p-Type additive) 
##STR9## 
##STR10## 
______________________________________ 
table 3 
______________________________________ 
ratio of 
Ratio of Components 
Transmissions of 
State of 
No. A B C Light Orientation 
______________________________________ 
16 100 0 5 .about.100 TN orientation 
17 100 10 10 130 " 
18 100 20 10 180 " 
19 100 30 10 210 " 
20 100 40 10 210 " 
21 100 50 10 210 " 
22 100 60 10 210 " 
23 100 70 10 210 " 
______________________________________ 
TABLE 4 
______________________________________ 
Angle of Ratio Ratio of 
Oblique of Components Transmissions 
State of 
Evaporation 
A B C of Light Orientation 
______________________________________ 
60.degree. 
100 30 10 0 Longitudinal 
orientation 
65.degree. 
100 30 10 0 " 
70.degree.C 
100 30 10 0 " 
82.degree. 
100 30 10 0 " 
______________________________________ 
EMBODIMENT 4 
An electrode film of indium oxide was formed on a 16 mm long and 16 mm wide 
plate of quartz by an electron beam evaporation method. 64 Substrates thus 
formed were disposed within the vacuum bell jar. Adjacent the substrate 
there were disposed a louver and a lateral lattice whose direction is 
orthogonal to that of the louver. Each of the leaves constituting the 
louver has the angle of 30.degree., interval of 10 mm and width of 20 mm, 
and the lateral lattice has the lattice width of 20 mm and lattice 
interval of 10 mm. Magnesium fluoride was evaporated onto the substrate at 
a vacuum pressure of 5 .times. 10.sup.-3 mmHg for five minutes. 64 sheets 
of alignment film thus formed were 200 .+-. 70 A thick on the average. 
Two sheets of substrates were spaced 9, 6, 3 .mu.m away from each other, 
between which a mixture liquid crystal of shiff base of propyl benzylidene 
cyano aniline and hexyl benzylidene cyano aniline was injected to provide 
a liquid crystal display cell. A predetermined optical system and signal 
circuit were provided to measure the properties of the display cell. The 
time of response till the operation as the display cell after the 
application of electrical signals was about 200 msec for the 9 .mu.m 
interval between the substrates, about 120 msec for the 6 .mu.m interval 
and 40 msec for the 3 .mu.m interval. 
For the alignment film formed by the conventional oblique vacuum 
evaporation method, the minimum interval between the substrates was 9 
.mu.m and the shortest time of response was about 200 msec. 
EMBODIMENT 5 
Two sheets of commercially available 2.5 mm thick, 230 mm long and 38 mm 
wide nesa glass were disposed in an evaporation device so that the 
alignment direction of leaves may be parallel to the longitudinal 
direction of the sheets of nesa glass. A spiral heater of tungsten was so 
disposed that the upper portion of the heater appears slightly above 
powders of SiO in a boat (34 mm in diameter) of molybdenum. The distance 
between the evaporation source and the louver was 41 cm and the distance 
d.sub.o between the louver and the sheet of nesa glass was 12 mm. 
The leaves were made of a plate of nickel having the thickness of 0.4 mm 
and the leaf width of 20 mm with the leaf angles of 15.degree. and leaf 
interval of 10 mm. The heater of tungsten was operated to heat at 
temperatures of about 1000.degree. C and evaporate SiO at a pressure of 5 
.times. 10.sup.-4 Torr in the bell jar. The two evaporated sheets of 
substrate were divided and so disposed that the upper sheet of nesa glass 
may be orthogonal in a longitudinal direction to the lower sheet of nesa 
glass to provide an empty cell in cooperation with a spacer of 9 .mu.m 
organic macromolecular film between the sheets of glass. The glass plates 
were adhesively fixed at their edge portions with an epoxy resin. A 
nematic liquid crystal (TN-200, made by Hoffmann la Roche) was injected 
into the empty cell to form a twisted liquid crystal display cell. 
The cell was sandwitched by two sheets of polarizer in order to examine the 
states of orientation. FIG. 12a shows the states of orientation of a 
conventional liquid crystal display cell, and FIG. 12b shows those of the 
display cell according to the present invention. As is apparent from the 
photograph, the liquid crystal formed by the method of the present 
invention has the capability of uniform orientation with very excellent 
display characteristics. 
EMBODIMENT 6 
In the present Embodiment, the description will be given to a forming 
method of an alignment film also serving as an electrode using an ion 
plating method. Its device is schematically shown in FIG. 13. In the 
figure, within a vacuum container 132 there are provided a negatively 
chargeable substrate holder 131, a glass substrate 133, a louver 134 at a 
grounded potential, and a evaporation material 135 of indium. An 
atmosphere adjusting device 138 is coupled to a base 137 of the container 
to adjust the vacuum container 132 to an oxygen gas pressure of 5 .times. 
10.sup.-3 mmHg. The application of a voltage of -2.0 KV to the substrate 
holder 131 causes the formation of a glow discharge region in the 
proximity of the substrate. The heating of the evaporation source 135 
causes particles of indium to pass through the louver 134, a portion of 
particles being ionized in the region of the glow discharge and deposited 
on the substrate in the form of indium oxide. The deposition for 15 
minutes resulted in the formation of about 1000 A thick surfactant of 
indium oxide. The substrates were filled therebetween with a liquid 
crystal, to which an electrical signal was applied by electrical circuits 
in combination with an optical system. This assured the operations as a 
display device. The alignment film of the liquid crystal also serves as 
the electrode. The intrusion of the ionized particles to the surface of 
the substrate in the region of the glow discharge improved the adhesion of 
the film to the substrate. 
EMBODIMENT 7 
A 70 mm long and 220 mm wide substrate of soda glass was washed with 
trichloroethylene and acetone to remove therefrom fat and dust and 
disposed in the vacuum evaporation container (bell jar) 88 as shown in 
FIG. 8. A louver and a lateral lattice whose direction is orthogonal to 
the louver were disposed adjacent the substrate. The leaves constituting 
the louver have an angle of 30.degree., are 5 mm spaced and 10 mm wide, 
and the lateral lattice has a lateral width of 20 mm and a lattice 
interval of 5 mm. After the vacuum evaporation container 88 was reduced in 
pressure to a vacuum pressure of 2 .times. 10.sup.-5 Torr, a gas of oxygen 
was leaked to set the vacuum pressure to 5 .times.10.sup.-3 Torr. Powders 
of indium oxide (In.sub.2 O.sub.3) added with 5% by weight of powders of 
tin oxide (SnO.sub.2) were moulded at a pressure of 50 kg/cm.sup.2 to a 
cylindrical pellet of 15 mm.sup..phi. .times. 10 mm.sup.t, which was 
heated for about 7 minutes by electron beams for evaporation on the 
substrate. The formed thin film of indium oxide and tin oxide was 300 .+-. 
50 A thick. The electrical resistance of the thin film was further 
measured by a four-probe-method, and it was 0.05 .OMEGA..sup.. sq. Thus, 
the thin film exhibited an excellent conductivity. 
The two above-mentioned substrates were combined in a similar manner to 
that in Embodiment 1 to provide a liquid crystal cell, into which a mixed 
liquid crystal of shiff base of propyl benzylidene cyano aniline and hexyl 
benzylidene cyano aniline in equal amounts by weight was injected. 
A rectangular AC voltage signal of 1 KHz was applied in the same manner as 
in Embodiment 1 across the thin films of indium oxide and tin oxide 
respectively formed on the two substrates of the liquid cell to measure 
the voltage-brightness characteristic of the liquid crystal cell with the 
result of excellent characteristics, a threshold voltage of about 3 V, a 
voltage of about 5 V at which the transmission of light is saturated and a 
contrast of 200.