JPS62250418A - Ferroelectric liquid crystal pannel - Google Patents

Abstract

PURPOSE:To obtain the titled pannel having an improved memory effect by vacuum-depositing an inorg. substance on a substrate from an inclined direction so as to be a surface structure in which the deposited inorg. substance makes fine protruding groups in a certain direction, thereby orientating the liquid crystal molecules so as to have a minimum elastic deformation structure. CONSTITUTION:A tantalum board is used as the depositing source 93, and silicon monoxide is used as the depositing substance. The substrate 92 is formed by depositing conductive indium.tin oxide on the glass substrate. The angle of deposition is used for example, 85 deg. and 60 deg.. Thus, the titled pannel is formed by using the ITO substrate which is deposited in the inclined direction. The ferroelectric liquid crystal substance is composed of a mixture of ester type compds. The titled pannel having a good orientated monodomain structure is obtd. by pouring the ferroelectric liquid crystal in a cell at vacuum, followed by cooling slowly it.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to display devices, and particularly to ferroelectric liquid crystal panels.

Conventional technology The conventional technology will be explained below using figures.

First, the ferroelectric liquid crystal itself will be explained.

FIG. 3 is a schematic diagram of ferroelectric liquid crystal molecules. Ferroelectric liquid crystals are usually called smectic liquid crystals and have a layered structure. The molecules have a structure tilted by θ with respect to the perpendicular direction of the layer.

Further, ferroelectric liquid crystals are usually composed of optically active liquid crystal molecules that are not racemic.

As shown in Figure 3, ferroelectric liquid crystal molecules have a permanent dipole moment that is spontaneously polarized in the direction perpendicular to the long axis of the molecule, and in the chiral smectic C phase, the conical shape (hereinafter referred to as You can freely cut the outside of the cone (called a cone). Further, the vector directed from the center point O of the cone toward the liquid crystal molecules is called the C director.

In the chiral smectic C phase, this C director can move freely outside the cone.

In FIG. 3, 21 is a liquid crystal molecule, 22 is a permanent dipole,
23 is a C director, 124 is a cone, 25 is a layered structure,
26 indicates the layer normal direction, and 27 indicates the tilt angle θ.

Furthermore, since ferroelectric liquid crystal molecules have asymmetric atoms, they usually have a twisted structure. This twisted structure is shown in FIG.

In FIG. 4, 31 is a liquid crystal molecule, 32 is a permanent dipole moment, 33 is a twist period, pinch L534 is a layer structure, 35 is a normal direction of the layer, and 36 is a tilt angle θ. When the cell thickness fd+ of a ferroelectric liquid crystal panel is thicker than the pitch (d>L), the ferroelectric liquid crystal usually exists in a twisted structure because the influence of the cell substrate surface does not extend to the center of the cell. .

However, when the cell layer is smaller than a pinch (d < L), the twisted structure is unraveled by the force of the substrate surface, and two regions where the molecules are parallel to the substrate surface appear as shown in FIG. In these two regions, the permanent dipole moments of the molecules point in opposite directions, one direction from the back of the paper to the front, and the other from the front to the back of the paper. Each of these corresponds to the tilt angle of the molecule with respect to the layer normal.

In FIG. 5, 41 is a liquid crystal molecule, 42 is a permanent dipole moment pointing from the back of the page to the front, 43 is a permanent dipole moment pointing from the front of the page to the back,
44 represents the layer structure, 45 represents the layer normal direction, and 46 represents the inclination angle.

Next, the operating principle of the ferroelectric liquid crystal will be explained using diagrams. In this way, when a ferroelectric liquid crystal cell is filled with ferroelectric liquid crystal whose pitch is larger than the cell thickness (d < L), the fifth
It will have two areas as shown in the figure. At this time, when an electric field is applied from the back side of the paper to the front side, all the permanent dipole moments point in the direction of the electric field, resulting in a state in which all molecules have an inclination angle of +θ as shown in Figure 6 (al). If the polarization axis direction of the polarizer P of the polarizing plate is made parallel to the long axis direction of the molecule and the polarization axis direction of the analyzer A is parallel to the short axis direction of the molecule (see Figure 6 fbl), the linearly polarized light passing through the polarizer P becomes is transmitted without undergoing birefringence and is blocked by analyzer A, resulting in a dark state.

Furthermore, when an electric field is applied in the opposite direction, the molecules all have a tilt of 10 as shown in Figure 6(b), and the linearly polarized light that passes through the polarizer becomes bright when it passes through the analyzer due to the birefringence effect. It will be done.

As described above, bright and dark states can be obtained depending on the positive and negative electric fields. Furthermore, in cells where the cell thickness is smaller than the pitch (d<l), the twisted structure is usually unraveled, so it is said that a memory effect occurs in which the molecules remain in the same state even after the electric field is removed.

Figure 6 ta1. In fbl, 51 is the direction of the electric field, 5
2 is the permanent dipole moment of the molecule, 53 is the layer structure, 54
represents the tilt angle θ, and 55 represents the polarization axes of the polarizer P and analyzer A, respectively.

The transmitted light intensity I in this bright state is given by the following equation.

1-11 sin24θ×sin 2 (rt a n
d / λ) ... (1) where Δn is the anisotropy of the refractive index of the ferroelectric liquid crystal, 11 is the incident light intensity after passing through the polarizer, λ is the wavelength, and θ is the liquid crystal molecule The tilt angle and d represent the thickness of the liquid crystal layer. This display method is generally called birefringence mode.

This equation can be expressed as the following equation in terms of brightness (Y value), which is the amount of brightness perceived by the human eye.

Y=l/Kot [3(λ) bow(λ)・y(λ)] d
λ・・・・・・(2) However, S(λ): Spectral distribution of light source (equal energy light source) ■ (λ); Spectral distribution of ferroelectric liquid crystal panel y(λ):
Visibility curve integral range: 380 nm to 700 nm FIG. 7 shows a plot of this Y value against and (phase difference) using a calculation formula. At this time, the tilt angle θ was set to θ-22.5@ so as to take the brightest state.

It can be seen from FIG. 7 that the Y value changes greatly depending on and (phase difference). At this time, the color difference ΔEl (representing color unevenness due to cell thickness unevenness) due to cell thickness unevenness is plotted against and in FIG. 8. In FIG. 8, cell thickness unevenness is calculated assuming 0.2 μm. The color difference was calculated using the CIELAB uniform color difference space using the following equation.

ΔE*−[(ΔL*) 2 + (Δa*)2+(Δb
'l')2] ......(3) However, L*-116(Y/Y0) -16 a *-500[(X/X0)-(Y/Y,)]b*-
20Or (Y/Y0)-(Z/Z,)] where X,,
Y, , Z0 are the tristimulus values of the reference white surface, and X, Y, Z
indicates the tristimulus values of the colorimetric object. ΔL*, Δa*, Δ
b* is L*, a*, b* in different colorimetric objects
Here, it shows the difference between a certain cell thickness fd) and a cell thickness 0.2 μm thicker (d+0.2 μm). From Figures 7 and 8, it can be seen that the brightest and (phase difference) with the smallest color difference (color unevenness) is approximately 0.28 μm.The birefringence anisotropy (Δn
) and usually 0.13~Q, L8, so the cell thickness is 1.
It can be seen that it is necessary to make the film very thin, about 5 to 2.2 μm.

(Reference: Fukuda, Takezoe, Kondo, High-speed display using diferroelectric liquid crystal, Obtronics, 9th edition.

64, 1983) However, in order to use the display method described above, the ferroelectric liquid crystal layer must be oriented in a certain way, as shown in Figure 6 (al, (bl). Cells with this orientation are called monodomain cells.

Ferroelectric liquid crystals have a layered structure and are said to be more difficult to align than ordinary nematic liquid crystals.

Conventionally, shearing method, temperature gradient method, rubbing method, etc. have been used as means for aligning ferroelectric liquid crystals.

Among these orientation methods is the shearing method.

The temperature gradient method has the disadvantage of poor productivity.

The rubbing method is widely used for nematic liquid crystals and is also often used for ferroelectric liquid crystals. This rubbing method will be explained using figures.

Figure 9 ta1. (b) is a rubbing method of a ferroelectric liquid crystal that has a phase transition series from an isotropic liquid (Iso) to a smectic A phase (SmA) to a smectic C chiral phase (SmC*) exhibiting ferroelectricity. FIG.

Before explaining the orientation, the smectic human phase and the smectic C chiral phase will be explained using diagrams.

Figure 8 (al, (bl) is a schematic representation of the structure of the smectic A phase and the smectic C chiral phase, respectively. This figure is a ferroelectric liquid crystal panel viewed from the direction perpendicular to the substrate. Both the smectic A phase and the smectic C chiral phase have a layered structure, but in the smectic human phase, the long axis direction of the molecules is parallel to the layer line direction as shown in Figure 9 (al). It can be seen that in the smectic C chiral phase shown in FIG. 9(b), the long axis direction of the molecules is tilted by ±θ with respect to the direction of the interlayer lines.

Figure 9 tal, (in bl, 81 is a liquid crystal molecule, 82
is the layer structure, 83 is the molecular long axis direction, 84 is the layer stacking line direction, 8
5 represents the tilt angle θ, and 86 represents the rubbing direction of the upper and lower substrates.

Next, the orientation of a ferroelectric liquid crystal having such a phase transition series will be explained.

Figure 9<al is a schematic diagram of the orientation of molecules when transitioning from an isotropic liquid to a smectic A phase.Since the molecules are in the smectic A phase, their long axes are perpendicular to the layer structure. are doing. Therefore, when rubbing is applied, the long axes of liquid crystal molecules are aligned parallel to the rubbing direction (easy alignment axis), resulting in a zero-order smectic structure in which the layer is parallel to the layer stacking direction as shown in Figure 9, 18). When phase transition occurs from the A phase to the smectic C chiral phase exhibiting ferroelectricity, the layered structure requires a large amount of energy for elastic deformation, so molecules are tilted within the layer and the layered structure is maintained as it is. As a result, Figure 9 (
As shown in bl, the layer stacking line direction remains parallel to the rubbing direction, but the molecules are oriented deviated from the rubbing direction.

However, in such an alignment state, the ferroelectric liquid crystal molecules can move freely outside the cone within the layer as shown in FIG. 3, so it is conceivable that they return to the rubbing direction, which is the axis of easy alignment.

Next, a conventional example of vapor deposition will be shown.

Although the oblique vapor deposition method has traditionally been used in some cases to improve the orientation of nematic liquid crystals, the rubbing method is currently the mainstream. The oblique vapor deposition method will be explained using figures.

The actual method of oblique vapor deposition is shown in FIG.

There is a deposition source inside a vacuum deposition vessel (pellger), which can be heated by passing an electric current through it. The cell substrate is set at an angle of θ with respect to the vapor deposition direction from the direction perpendicular to the substrate.

91 - Herger, 92 - Cell substrate 93 - Vapor deposition source, 94 - Tilt angle θ By performing oblique vapor deposition, a structure in which countless small column-shaped protrusions 101 are present on the surface as shown in FIG. 11 is created. This is usually said to be caused by an effect called self-shadowing. At this time, by changing the tilt angle θ102, a difference occurs in the orientation of the nematic liquid crystal molecules. This will be explained using figures.

(1) When evaporation angle/degree (θ) is 75@~85°, θ is 75
As shown in Figure 12 (al) when the angle is between 85° and 85'', the liquid crystal molecules are oriented with their long axis direction +nl 111 parallel to the deposition direction.For this reason, the liquid crystal molecules have a pretilt angle of about 15 degrees to 30 degrees. has been done.

(2) When the deposition angle (θ) is ~60@ When θ is ~60 degrees, the liquid crystal molecules are aligned with their long axes perpendicular to the deposition direction as shown in Figure 11 (bl).In this case, the pretilt angle is approximately 0 degrees.

It is said that the difference in orientation due to the difference in deposition angle depends on which direction the molecules are aligned with respect to the column structure on the surface to minimize the energy of elastic deformation.

There are a few examples in which oblique vapor deposition was used as an orientation method for smectic liquid crystals or ferroelectric liquid crystals. However, they are used in a state where the cell thickness is thick (~7 μm or more), and the voltage-luminance curve (
BV curve), etc., and there is almost no mention of its usefulness as a pretilt angle display device.

References for oblique deposition method: (1) Taplu, Ulbach, M, Boix.

Guillon, E.; Orientation of nematic and smectic phases on deposited films, Abraillard Physics Letters, 2
Volume 5, No. 9 (1), page 479, 1974 (W, ur
bach+ M, Boix, and E, Guyo
n ; Alignment of nematics
andsmec-tics on evaporat
ed fi1ms+ Applied Physics
s Letters, VOL, 25. NO, 9, I
P, 479November 1974) (2) Tsutomu Uemoto, Yasube Iwasaki, Katsumi Yoshino, Yoshio Oishi; Electro-optical properties of smectic ferroelectric liquid crystals (2), 4th
Liquid Crystal Symposium Proceedings (1978) Lecture Number 3R13 Problems to be Solved by the Invention (1) Conventionally, an industrially advantageous rubbing method was used to control the alignment of ferroelectric liquid crystals, but this method The problem is that the memory effect is small when voltage is applied to ferroelectric liquid crystal molecules. This will be explained below using figures.

FIG. 13 (al, (b), fc) schematically shows a state in which a voltage is applied to a ferroelectric liquid crystal panel subjected to rubbing alignment. Here, FIG. 13 (al indicates a state in which a voltage is applied from the back side of the page to the back side, the 13th exit) shows a state in which a voltage is applied from the front side to the back side of the page.

In these two states, most of the ferroelectric liquid crystal layer is oriented in the direction of the electric field. Therefore, by appropriately determining the positions of the polarizer and analyzer, bright and dark states can be obtained depending on the polarity of the electric field.

The steps up to this point are the same as those in Figure 6 (tag and (bl).Next, when the electric field is set to zero, that is, no application is applied, the ferroelectric liquid crystal molecules return to the rubbing axis, which is the axis of easy alignment, and the first
Figure 3 (This results in a state like C1, which is, after all,
This indicates that memory performance has deteriorated.

Figure 13 1al, Tol, [12 in cl.
1 represents a ferroelectric liquid crystal molecule, 122 represents a layer structure, 123 represents a rubbing direction, and 124 represents an electric field direction.

In order to demonstrate these facts, a liquid crystal panel as shown in FIG. 14 was prepared by rubbing.

Here, 131 is the upper and lower polarizing plate, 132 is the upper and lower glass substrate, 133 is a transparent electrode layer, 134 is an organic polymer film layer subjected to alignment treatment, 135 is a ferroelectric liquid crystal layer, and 136 is the distance between the opposing substrates. It represents a spacer for keeping (cell w,) constant. In this way, a ferroelectric liquid crystal panel was created by sealing ferroelectric liquid crystal between the opposing electrodes.

The ferroelectric liquid crystal material used in the experiment was an ester-based liquid crystal material that exhibits ferroelectricity in the temperature range of 0°C to 58°C. The phase transition temperature of the ferroelectric liquid crystal used below is shown.

Cr-SmCSmA Ch ～0℃　　58℃　　82℃ 111→Is.

95℃ Here, Cr: Crystal phase SmC: Smectic C chiral phase SmA: Smectic A phase Ch: Cholesteric phase I30: Isotropic liquid Also, the birefringence anisotropy ('n) of this crystal is a Senarmont type compensator. It was 0.14 when measured using.

The orientation direction is determined by rubbing the organic polymer film provided on the glass substrate, and after injecting the liquid crystal, heating the panel to 100°C to make it an isotropic liquid, and then slowly cooling it (0.6°C/m1n).
), a smectic C chiral phase monodomain was obtained.

Next, using this panel, a voltage-transmittance curve (hereinafter referred to as B-
V curve) was measured.

FIG. 15 shows the optical experimental system used for measuring the BV curve. In FIG. 15, white light emitted from a light source 141 passes through a polarizer 142 and enters a liquid crystal cell 143 as linearly polarized light, passes through an analyzer 144, is focused by a condensing lens 145, and is sensed by a photomultiplier tube 146. , is measured by the storage oscilloscope 147 as a BV curve. Furthermore, the liquid crystal cell has a program pulse generator 148.
Now you can add arbitrary waveforms.

In such an experimental system, the BV curve of the ferroelectric liquid crystal panel having the above-mentioned configuration was measured.

Further, the cell thickness of the ferroelectric liquid crystal panel used was 2.8 μm.

The obtained BV curve is shown in Figure 16. In Figure 16, the horizontal axis is time (tl), and the vertical axis is voltage V or brightness B. Figure 16 (al is the applied voltage waveform). ,
Fig. 16 (bl is the corresponding brightness curve. Fig. 16 is explained in the order of voltage waveforms. First, the pulse height +10
v3 width 2, brightness is about 3 when a voltage of Qma is applied
A bright state as large as 2% was obtained when no voltage was applied to the 0th order (O
It can be seen that the brightness decreases at the time of v), and the molecules return to the rubbing direction.

Further, when a voltage of -1 Ov is applied, the brightness decreases to about 1%, which is the darkest state. However, when the voltage is not applied again, the brightness increases again and becomes the same brightness as the previous state when no voltage is applied. This is due to the molecules returning when no electric field is applied, indicating that there is no memory effect.

(2) Conventionally, ferroelectric liquid crystal panels utilize the birefringence effect, so it has been necessary to make the cell thickness very thin, about 2 μm, in order to reduce brightness and color unevenness. This was extremely disadvantageous in terms of productivity.

Means for solving the problem (1) Instead of uniaxial processing using the conventional rubbing method, the inorganic material is applied diagonally to create a surface structure in which the inorganic material has a group of minute protrusions in a certain direction. This surface structure causes the liquid crystal molecules to align in a structure with the least elastic deformation.

The alignment due to this effect is different from the uniaxial treatment using the rubbing method, and it is possible to realize a ferroelectric liquid crystal panel with a large memory effect.

(2) In conventional ferroelectric liquid crystal panels, the ferroelectric liquid crystal molecules are oriented with a tilt angle (hereinafter referred to as pretilt angle) of almost 0 degrees with respect to the substrate surface, so the cell thickness is limited to ~2 μm. It had to be fairly thin. but,
By increasing the pretilt angle, the apparent anisotropy (Δn) of the upper refractive index can be decreased. As a result, the cell thickness fd+ can be made thicker than in the conventional method, and a ferroelectric liquid crystal panel with good productivity can be realized.

Effect (1) Unlike the uniaxial treatment using the rubbing method, by applying the inorganic material from an oblique direction, the surface structure of the material is created such that the material has a group of minute protrusions in a certain direction. This surface structure causes the liquid crystal molecules to align in a structure with the least elastic deformation.

The resulting orientation is different from the strong uniaxial treatment using the rubbing method, and it is possible to realize a ferroelectric liquid crystal panel with a large memory effect.

(2) By reducing the apparent Δn by having a large pretilt angle with respect to the substrate surface, it is possible to obtain a bright ferroelectric liquid crystal panel with less coloring even when the cell thickness is increased, increasing productivity. A good ferroelectric liquid crystal panel can be realized.

Example An embodiment of the present invention will be described below with reference to the drawings.

Example 1 The oblique vapor deposition method used in this example was performed using the configuration shown in FIG. 10 described in the conventional example.

A tantalum board was used as a deposition source, and silicon monoxide (Sin) was used as a deposition material.

The substrate used was a glass substrate on which conductive indium and tin oxide were deposited (ITO substrate).

Both 85 degrees and 60 degrees were used as the deposition angle. The deposition rate was about 20 people/sec, and the film thickness was about 800 people per second in the direction perpendicular to the substrate.

A ferroelectric liquid crystal panel was created using the ITO substrate subjected to oblique vapor deposition in this manner. The cell configuration is essentially the same as that shown in FIG.

The deposition directions of the upper and lower substrates were made to be antiparallel.

The ferroelectric liquid crystal material used in the examples is the same ester mixture as used in the conventional examples.

By injecting ferroelectric liquid crystal into such a cell in a vacuum and slowly cooling it, a well-oriented monodomain ferroelectric liquid crystal panel was obtained. The cell thickness was 3 μm.

The orientation at this time differed depending on the deposition angle.

When the deposition angle was 85 degrees, the long axis direction of the liquid crystal molecules coincided with the deposition direction, but when the deposition angle was 60 degrees, the long axis direction was perpendicular to the deposition direction.

The BV curve of this ferroelectric liquid crystal panel was measured using the optical system described in the conventional example, and the memory effect was investigated. The results are shown in Fig. 1 (ial, fbl) and Fig. 2 (a), mountain).

Here, FIG. 1 +a+, (bl is a ferroelectric liquid crystal panel in which the deposition angle is 85 degrees, and FIG. 2 (al, (bl is 60 degrees).

This will be explained using FIG. 1 (al, (bl).

From Figure 1 (al, (bl), when a pulse with pulse height + IOV, width 2, and Qn was applied, a bright state with a brightness of approximately 32% was obtained.Next, when no voltage was applied (Ov), a bright state was obtained. Even when the pulse is applied, the brightness remains the same and the molecules are in the same location as when the pulse was applied, indicating a memory effect.

Further, when a pulse of -10V was applied, the brightness decreased to about 1%, which was the darkest state.

It can also be seen that even when no voltage is applied, the brightness remains the same and the memory effect is strong.

This is the same for Tal and (bl) in Figure 2, and a strong memory effect was obtained whether the deposition angle was 85 degrees or 60 degrees.

Example 2 Changes in hue were measured using a cell in which the cell thickness was gradually increased in a rust-like pattern.

The structure of the wedge-shaped cell is shown in FIG.

In Fig. 17, 161 is a glass substrate, 162 is an ITO
163 is a ferroelectric liquid crystal layer; 164 is a spacer for adjusting the cell thickness;
5 indicates the combination of the deposition direction or the rubbing direction.

The change in cell thickness is 1 μm to 7 μm, 85 degree evaporation, 6
Ferroelectric liquid crystal panels oriented by 0-degree vapor deposition and rubbing methods were prepared. The luminance and hue of these ferroelectric liquid crystal panels in an electric field due to differences in cell thickness were measured using a colorimeter manufactured by Macbeth.

First, FIG. 18 shows the relationship between cell thickness and brightness for 60 degree evaporation and rubbing cells.

Here, the mark Q indicates 60 degree evaporation, and the mark x indicates a rubbing cell.

Next, FIG. 19 shows the relationship between cell thickness and brightness of a ferroelectric liquid crystal panel deposited at 85 degrees.

The relationship between cell thickness and brightness of a ferroelectric liquid crystal panel is theoretically given by equation (1) as described in the conventional example.

The brightness curve given by the theoretical formula in Figure 7 is approximately
The brightest state is reached when and is about 0.28. From FIG. 18, both the 60 degree vapor deposition cell and the rubbing cell are at their brightest when the cell thickness is approximately 2.0 μm, and the liquid crystal material of this example is Δ
Since n is approximately 0.13, And is approximately 0.28, which corresponds to the theoretical formula.

In the 85 degree evaporation cell shown in FIG. 19, the cell thickness at which the brightness is the highest is approximately 2.6 μm, and And is approximately 0.36, which indicates that the cell thickness is brighter than the theoretical formula.

This is considered to be because, as described in the explanation of the oblique vapor deposition method, 85 degree vapor deposition has a large pretilt angle.

Apparent birefringence anisotropy (Δn
) is Aneff, and the pretilt angle is θp, Aneff is given by the following equation from the formula of the refractive index ellipsoid.

ΔneH=Δn'cOa2 θp ・-・
・e(η Here, the actual pretilt angle was measured.

Since it is difficult to measure the pretilt angle in a ferroelectric liquid crystal state, a nematic liquid crystal was used. The pretilt angle was measured using a method called the null capacitance method.

As a result, it was found that the pretilt angle of the 85 degree vapor deposition cell was approximately 25 degrees. By substituting the pretilt angle of 25 degrees and the value of Δn of 0.13 into equation (7), Aneff
has a value of 0.107.

According to the theoretical calculation using the Tl1 formula, the brightest And is about 0.28, so the cell thickness is 2.0 when Δn is 0.13.
1μm was required, but in order to adjust the pre-tilt angle,
When eff is as small as 0.115, the cell thickness is approximately 2
．． It will be the brightest at 6 μm. This almost agrees with the results of measuring the brightness of the 85 degree evaporation cell.

Next, Δ when increasing the pretilt angle from 0 degrees
FIG. 20 shows a plot of changes in neff/Δn.

From Figure 20, when the pretilt angle is about 10 degrees, Δ
It can be seen that neff/Δn does not change much from 1, and Aneff does not become much smaller.

It has been found that when the pretilt angle is 10 degrees or more, the amount of change in Δneff/Δn becomes large, Aneff becomes small, and a bright state can be obtained even if the cell thickness is thick.

It was also found that the oblique vapor deposition method is a good method for increasing the pretilt angle without impairing the orientation of the ferroelectric liquid crystal panel.

Effects of the Invention (1) The present invention has the effect that a ferroelectric liquid crystal panel with strong memory properties and good display quality can be obtained by aligning ferroelectric liquid crystal using an oblique vapor deposition method.

(2) In addition, by having a large pretilt angle, the apparent Aneff d of the ferroelectric liquid crystal panel is reduced, making it possible to create a bright ferroelectric liquid crystal panel even with thick cells. This has the effect of improving productivity.

(3) A large pretilt angle can be obtained along with good alignment by the oblique vapor deposition method, which has the effect of making it possible to obtain a ferroelectric liquid crystal panel that has strong memory properties and good cell thickness productivity.

[Brief explanation of drawings]

Figure 1 fat, (bl and Figure 2 al, (bl is a characteristic diagram showing the memory properties of a ferroelectric liquid crystal panel subjected to oblique vapor deposition, Figure 3 is a schematic diagram showing the structure of ferroelectric liquid crystal, Figure 4 is a schematic diagram showing the twisted structure of ferroelectric liquid crystal, a schematic diagram showing the operating principle in a ferroelectric liquid crystal panel with a small cell thickness, and Figure 7 is the relationship between And and brightness of a ferroelectric liquid crystal panel. Figure 8 is a graph plotting the theoretically calculated values of color difference as cell thickness unevenness for each And in a ferroelectric liquid crystal panel.
Figure +1), (bl is a schematic diagram showing the structure of the SmA phase and SmC* phase and the orientation state when rubbing is performed, Figure 10 is a schematic diagram showing the evaporation apparatus and method, and Figure 11 is a diagram showing the oblique evaporation. Schematic diagram showing the surface condition when the process is carried out, Figure 12f
at, fbl is a schematic diagram showing the alignment direction of liquid crystal molecules when the vapor deposition direction is changed, Fig. 1318+, (bl, f
cl is a schematic diagram showing the operation of ferroelectric liquid crystal by applying an electric field by the rubbing method and the small memory effect, No. 14
Figure 15 is a structural diagram of the ferroelectric liquid crystal panel used in the conventional example and example, Figure 15 is a schematic diagram of the wedge-shaped cell used for color measurement, and Figure 18 is a rubbing cell. Figure 19 is a graph plotting the measured values of cell thickness and brightness for a 60 degree evaporation cell, Figure 20 is a graph plotting the actual value of cell thickness and brightness for an 85 degree evaporation cell, and Figure 20 is the calculation of the pretilt angle and Δnef f. This is a graph plotting values. 121... Ferroelectric liquid crystal molecules, 122...
...Layer structure, 123...Rubbing direction, 124
...Direction of electric field, 131 ...Polarizing plate,
132・Old...Glass substrate, 133...Transparent electrode layer, 134...Organic polymer film layer, 135...
...Ferroelectric liquid crystal layer, 136...Spacer. Name of agent Patent attorney Toshio Nakao 1 person Figure 1 (Yamaa 8% Lock<rnser-+ Figure 2 (QJ+ (b) Between (-δec) Figure 3s Figure 4 Figure 5 Figure 6 original part, 71 [(z] Figure 9 Figure 10 (J 0 Figure 14 Figure 15 Figure 16 Figure 1ts interval (rnsec) Figure 18 t: No L, No 1 copy - (Metsu Town No. 19 Figure v L 4 (μm) Figure 20 Tortoise angle 1 dql

Claims (5)

[Claims] (1) A liquid crystal layer and a plurality of substrates, at least one of which is transparent, arranged to sandwich the liquid crystal layer, and a voltage application means attached to the substrate so as to apply a voltage to the liquid crystal layer. A ferroelectric liquid crystal panel characterized in that the orientation of ferroelectric liquid crystal is controlled by vapor-depositing an inorganic substance from an oblique direction with respect to a substrate in the panel. (2) A ferroelectric liquid crystal panel according to claim (1), wherein the inorganic substance is silicon oxide. (3) A liquid crystal layer and a plurality of substrates, at least one of which is transparent, arranged to sandwich the liquid crystal layer, and a voltage application means attached to the substrate so as to apply a voltage to the liquid crystal layer. A ferroelectric liquid crystal panel, characterized in that the ferroelectric liquid crystal has an inclination angle of 10 degrees or more with respect to the surface of at least one substrate in the panel. (4) A ferroelectric liquid crystal panel according to claim (3), characterized in that an inorganic substance is deposited obliquely as means for imparting a tilt angle. (5) A ferroelectric liquid crystal panel according to claim (3) or (4), characterized in that the ferroelectric liquid crystal panel has a cell thickness of 5 μm or less.