JPS6397917A - Ferroelectric liquid crystal panel - Google Patents

Abstract

PURPOSE:To obtain a ferroelectric liquid crystal panel having a strong memory characteristic and good display grade by depositing silicon dioxide by vapor deposition on a substrate from a diagonal direction to execute the orientation control of a ferroelectric liquid crystal. CONSTITUTION:The silicon dioxide (SiO2) is used as a material 93 for vapor deposition and is heated by projecting an electron beam thereto, by which the vapor deposition is executed. A glass substrate on which conductive indium.tin oxide is deposited by evaporation (ITO substrate) is used as the substrate 92. The vapor deposition is executed by using 85 deg. and 60 deg. as a vapor deposition angle to form the film to about 3,000Angstrom thickness in the direction perpendicular to the substrate. The substrate is made into such a surface structure which has fine projecting groups in the certain specified direction by the vapor deposition of the inorg. material (Al2O3) from the diagonal direction in the above- mentioned manner and, therefore, the liquid crystal molecules are eventually oriented to the structure having the least elastic deformation. The ferroelectric liquid crystal panel having a high memory effect is thereby obtd.

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 with reference to the drawings.

First, the ferroelectric liquid crystal itself will be explained.

FIG. 2 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 2, 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 can move freely outside the cone (called a cone). Also, the vector drawn from the center point 0 of the cone toward the liquid crystal molecules is called a C director.

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

In Figure 2, 21 is a liquid crystal molecule, 22 is a permanent dipole, 2
3 is a C director, 124 is a cone, 25 is a layered structure, 2
Reference numeral 6 indicates the layer normal direction, and reference numeral 27 indicates the inclination 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 Figure 3, 31 is a liquid crystal molecule, 32 is a permanent dipole moment, 33 is a pitch (L) representing the period of twist, and 34
represents the layer structure, 35 represents the normal direction of the layer, and 36 represents the inclination angle θ. When the cell thickness (d) of a ferroelectric liquid crystal panel is thicker than the pitch (d>L), the ferroelectric liquid crystal usually has a twisted structure because the influence of the cell substrate surface does not extend to the center of the cell. exist.

However, when the cell thickness is smaller than the pitch (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. 4, 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 fourth
It will have two areas as shown in the figure. At this time, when an electric field is applied from the back to the front of the paper, all the permanent dipole moments are directed in the direction of the electric field, and all the molecules have an inclination angle of +θ as shown in FIG. 5(a). In this state, 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 made parallel to the short axis direction of the molecule (Figure 5 (a) Reference) The linearly polarized light that has passed through the polarizer (P) is transmitted without undergoing birefringence and is blocked by the 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 -θ 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 5(a) (In bl, 51 is the direction of the electric field, 52
is the permanent dipole moment of the molecule, 53 is the layered structure, 54 is the tilt angle θ, and 55 is the polarization axis of the polarizer (P) and analyzer (A), respectively.

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

r=I, sin"4θX5in"(πΔnd/λ)□(
1) Here, Δn is the anisotropy of the refractive index of the ferroelectric liquid crystal, ■, is the intensity of the incident light after passing through the polarizer, λ is the wavelength, θ is the tilt angle of the liquid crystal molecules, and d is the thickness of the liquid crystal layer represents. 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/KO/ (S (λ)・I (λ)・
y (λ)] dλ □ (2) However, S (λ): Spectral distribution of light source (equal energy light source) ■ (λ) Spectral distribution of biferroelectric liquid crystal panel y (λ):
Visibility curve integral range: 380nm to 700nn + this Y value as An
FIG. 6 shows a plot of d (phase difference) using a calculation formula. At this time, the tilt angle θ was set to θ=22.5” to obtain the brightest state.

From FIG. 6, it can be seen that the Y value changes greatly depending on And (phase difference). Further, FIG. 7 shows a plot of the color difference ΔE* (representing color unevenness due to cell thickness unevenness) due to cell thickness unevenness at this time versus And. In FIG. 7, the cell thickness unevenness was calculated assuming 0.2 μm. The color difference was calculated using the CI ELAB uniform color difference space using the following equation.

ΔE*=((ΔL water)2 + (Δa*) !+(
Δb*) ”) −(31 However, L)1′= 116 (Y/Yo ”) −16a
*= 500 ((X/Xo) −(Y/Yo)
)b *= 200 ((Y/Yo) −(Z/Z
o)) Here, Xo, Yo, and Zo are the tristimulus values of the reference white surface, and X, Y, and Z are the tristimulus values of the colorimetric object. ΔL*, Δa*, Δb* are L in different colorimetric objects
It shows the difference between *, a*, and b*, where a certain cell thickness (d) and a cell thickness 0.2 μm thicker (d + 0.
2 μm). From FIGS. 6 and 7, it can be seen that Δnd (phase difference), which is the brightest and has the smallest color difference (color unevenness), is about 0.28 μm. It can be seen that since the birefringence anisotropy (Δn) of ferroelectric liquid crystal is usually 0.13 to 0.18, the cell thickness needs to be very thin, about 1.5 to 2.2 μm.

(References Nifukuda, Takezoe, Kondo, High-speed display using biferroelectric liquid crystal, Obtronics, No. 9, p. 64, 19
(1983) However, in order to use the above display method, the ferroelectric liquid crystal layer must be oriented in a certain way as shown in Figure 5(a) (bl). Cells in which this is done 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.

Due to these orientations, the shearing method and temperature gradient method have 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.

Figures 8(a) and 8(b) show a strong liquid with a phase transition sequence from an isotropic liquid (Iso) to a smectic A phase (SmA) to a smectic C chiral phase (SmC*) exhibiting ferroelectricity. It is a schematic diagram when dielectric liquid crystal is oriented by the rubbing method.

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

Figure 8 (al (b)) is a schematic representation of the structure of the smectic A phase and the smectic C chiral phase. This figure is a view of 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 A phase, the long axis direction of the molecules is parallel to the synergistic line direction, as shown in Figure 8 (a). Figure 8 (
It can be seen that in the smectic C chiral phase b), the long axis direction of the molecules is tilted by ±θ with respect to the direction of interlayer lines.

In FIG. 8 (al (b)), 81 is a liquid crystal molecule, 82 is a layer structure, 83 is a molecule long axis direction, 84 is a layer line direction, 85
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 8 (al is a schematic diagram of the orientation of molecules when transitioning from an isotropic liquid to a smectic A phase; here, since the molecules are in the smectic A phase, their long axis of the molecules is perpendicular to the layer structure. Therefore, when rubbing is applied, the long axis of the liquid crystal molecules is aligned parallel to the rubbing direction (easy alignment axis), and as a result, the layer line direction and the layers are parallel to each other as shown in Figure 8 (a). Become.

Next, when phase transition occurs from the smectic 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, as shown in FIG. 8 (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. 2, so it is conceivable that the ferroelectric liquid crystal molecules return to the rubbing direction, which is the axis of easy alignment.

Conventional example of oblique deposition.

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

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

A vapor deposition source is located in a vacuum vapor deposition pot (pellger), and can be heated by resistance heating or electron beam irradiation. The cell substrate is tilted by an angle θ from the substrate perpendicular direction to the vapor deposition direction.

91 is a Pelger, 92 is a cell substrate, 93 is an evaporation source, 9
4 has an inclination angle θ, and by performing oblique vapor deposition, a structure in which countless small column-shaped protrusions 101 are present on the surface as shown in FIG. 10 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 the drawings.

■When the deposition angle (θ) is 75° to 85°, θ is 75° to 8
When the pretilt angle is 5 degrees, as shown in Figure 11 (al), the liquid crystal molecules are aligned with their long axis (n) 111 parallel to the deposition direction.For this reason, the liquid crystal molecules change the pretilt angle from 15 degrees to 3 degrees.
It is said to have a temperature of about 0 degrees.

(2) When the deposition angle (θ) is ~60° When θ is ~60° As shown in FIG. 11(b), the liquid crystal molecules are aligned with their long axes perpendicular to the deposition direction. At this time, 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 surface column structure 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 evaporation method: ■Double, Albabuk, M, Voix, E.

Guillon: Orientation of nematic and smectic phases on deposited films, Alived Physics Letters, vol. 25
No. 9 (1) 479 pages 1974 (W, tlrba
Ch.

M, Boix, and E, Guyon; Al
ignment of nematics and s
mectics on evaporated
films, Applied Physics L
etters, Vol, 25+ No, 9+I
P, 479 Novem-ber 1974) ■ Tsutomu Kamiki, Yasube Iwasaki, Katsumi Yoshino, Yoshio Oishi; Electro-optical properties of smectic ferroelectric liquid crystals (2), Proceedings of the 4th Liquid Crystal Symposium (1978) Lecture Number R13 Problems to be Solved by the Invention (1) Conventionally, an industrially advantageous rubbing method has been used to control the alignment of ferroelectric liquid crystals, but in this method, voltage is not applied to the ferroelectric liquid crystal molecules. In this case, the problem was that the memory effect was small. This will be explained below using figures.

Figure 12(a) (bl (C1 is a schematic representation of the state in which a voltage is applied to a ferroelectric liquid crystal panel subjected to rubbing alignment.Here, Figure 12(a) is viewed from the back of the paper to the front. FIG. 12(b) shows a state in which a voltage is applied in the direction from the front to the back of the paper.

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 FIGS. 5(a) and 5(b). Next, when the electric field is reduced 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, resulting in a state as shown in FIG. 12(C). This ultimately shows that the memory performance has deteriorated.

In FIGS. 12(a), (b), and (c), 121 represents ferroelectric liquid crystal molecules, 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. 13 was prepared by rubbing. Here, 131 is an upper and lower polarizing plate, 132 is an upper and lower glass substrate, 133 is a transparent electrode layer, 134 is an organic polymer film layer subjected to alignment treatment, 1
35 represents a ferroelectric liquid crystal layer, and 136 represents a spacer for keeping the distance (cell thickness) between opposing substrates 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 θ°C to 58°C. The phase transition temperature of the ferroelectric liquid crystal used below is shown.

Cr--→SmC* SmA Ch~0℃
58°C 82°C −1→Is.

95°C Here, Cr: Crystal phase SmC*: Smectic C chiral phase SmA: Smectic A phase Ch: Cholesteric phase It was 0.13 when measured using.

The orientation method is to rub the organic polymer film provided on the glass substrate, and after injecting the liquid crystal, heat the panel to 100 °C to make it an isotropic liquid, and then slowly cool it (0.6 °C / 5 inches).
), 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. 14 shows the optical experimental system used for measuring the BV curve. In FIG. 14, 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 is equipped with a programmable pulse generator 1.
48 allows arbitrary waveforms to be added.

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 curves are shown in FIGS. 15(a) and 15(b).

In FIGS. 15(a) and 15(b), the horizontal axis is time (1), and the vertical axis is voltage (V) or brightness (B). The upper figure is the applied voltage waveform, and the lower figure is the corresponding brightness curve. Fig. 15 fat (b) will be explained according to the order of the voltage waveforms. First, the pulse height +1. OV, width 2. On+s
When this voltage was applied, the brightness was as high as about 32%, and a bright state was obtained. Next, when no voltage is applied (0■), the brightness decreases, and it can be seen that the molecules have returned to the rubbing direction. Further, when a voltage of -10V 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 Problems The orientation of the ferroelectric liquid crystal is controlled by depositing silicon dioxide obliquely onto the substrate.

Effect (11) Unlike uniaxial treatment using the rubbing method, inorganic substances (A
Inorganic substances (I, 03) are deposited from an oblique direction.
ALos) has a surface structure with 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 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 providing 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, which improves productivity. A good ferroelectric liquid crystal panel can be realized.

Example (Example 1) An example of the ferroelectric liquid crystal panel of the present invention will be described below with reference to the drawings.

The oblique evaporation method used in the example was performed using the configuration shown in FIG. 9 described in the conventional example.

Using silicon dioxide (S i O□) as a deposition material,
This was heated by irradiating it with an electron beam to perform vapor deposition.

The substrate used was a glass substrate on which conductive indium tin oxide was 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 3000 people per second in the direction perpendicular to the substrate.

A ferroelectric liquid crystal panel was created using the ITO substrate subjected to oblique evaporation 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 2.5 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 (dl is a 60 degree ferroelectric liquid crystal panel. The explanation will be made using FIG. 1 (al fbl).

From Figure 1 (a) and (b), pulse height + IOV, width 2
．． When a pulse of Oms was applied, a bright state with a brightness of about 32% was obtained. Next, even when no voltage is applied (0■), the brightness remains the same and the molecules remain in the same location as when the pulse was applied, indicating that there is a memory effect.

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

Furthermore, it can be seen that even when no voltage is applied, the brightness remains unchanged and the memory effect is strong.

This was the same in FIGS. 1(C) and 1(d), and a strong memory effect was obtained whether the deposition angle was 85 degrees or 60 degrees.

(Example 2) Next, changes in hue were measured using a wedge-shaped cell in which the cell thickness was gradually increased.

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

In FIG. 16, 161 is a glass substrate, 162 is an IT
163 is a ferroelectric liquid crystal layer, 164 is a spacer for adjusting the cell thickness,
165 indicates the combination of the deposition direction or the rubbing direction.

The change in cell thickness was 1 μm to 7 μm, 85 degrees vapor deposition, 60 degrees
Oriented ferroelectric liquid crystal panels were prepared by repeated vapor deposition and rubbing methods. The brightness and hue of these ferroelectric liquid crystal panels in an electric field due to differences in cell thickness were measured using a colorimeter. A color photometer manufactured by Macbeth was used.

First, FIG. 17 shows the relationship between cell thickness and brightness for 60 degree evaporation and rubbing cells.

Here, the O symbol indicates 60 degree vapor deposition, and the X symbol indicates a rubbing cell.

Next, FIG. 18 shows the relationship between cell thickness and brightness of a ferroelectric liquid crystal panel deposited at 85 degrees.

The relationship between the cell thickness and brightness of a ferroelectric liquid crystal panel is theoretically given by (112) as described in the conventional example.

The brightness curve given by the theoretical formula in Figure 6 is approximately
The brightest state is reached when Δnd is about 0.28. As can be seen from FIG. 17, 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, Δnd is approximately 0.28, which corresponds to the theoretical formula.

The 85 degree vapor deposition cell in FIG. 18 is the brightest (the cell thickness is about 2.6 μm, and Δnd is around 0.36, which means that it is brighter at a thicker cell 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 Δneff, and the pretilt angle is θp, Δneff from the second side of the refractive index ellipsoid is expressed by the following formula % Here, the actual pretilt angle was measured.

A nematic liquid crystal was used to measure the pretilt angle of the ferroelectric liquid crystal state.The pretilt angle was measured by 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. Substituting the pretilt angle of 25 degrees and the value of 0.13 of Δn into equation (7), Δneff
has a value of 0.107.

According to the theoretical calculation using equation (1), the brightest Δnd is approximately 0.28, so the cell thickness is 2.0 when Δn is 0.13.
1 μm was required, but since it has a pretilt angle, Δn
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. 19 shows a plot of changes in neff/Δn.

From Figure 19, when the pretilt angle is about 10 degrees, Δ
It can be seen that neff/Δn does not change much from 1, and Δneff does not become much smaller.

It was found that when the pretilt angle is 10 degrees or more, the amount of change in Δneff/Δn becomes large, Δneff 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 uses AlzOz as a vapor deposition substance and performs an oblique vapor deposition method to orient the ferroelectric liquid crystal, thereby obtaining a strong ferroelectric liquid crystal panel made of memory and having good display quality. It has the effect of

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

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

[Brief explanation of the drawing]

FIG.
The figure is a schematic diagram showing the structure of ferroelectric liquid crystal, Figure 3 is a schematic diagram showing the twisted structure of ferroelectric liquid crystal, and Figure 4 is a state in which the twisted structure is unraveled in a panel with a thin cell thickness of ferroelectric liquid crystal. (bl is a schematic diagram showing the operating principle in a ferroelectric liquid crystal panel with a thin cell thickness, Figure 6.
The figure is a graph plotting theoretically calculated values of the relationship between Δnd and brightness for a ferroelectric liquid crystal panel, and Figure 7 plots the theoretically calculated values of color difference as cell thickness unevenness for each Δnd in a ferroelectric liquid crystal panel. The graph shown in Figure 8 (al
(b) is a schematic diagram showing the structure of the SmA phase and SmC* phase and the orientation state when rubbing is performed, Figure 9 is a schematic diagram showing the evaporation apparatus and method, and Figure 10 is when oblique evaporation is performed. FIG. 11 is a schematic diagram showing the surface state of (al (bl
Figures 12(a), 12(b), and 12(c) show the behavior of ferroelectric liquid crystals and the small memory effect caused by applying an electric field using the rubbing method. 13 is a structural diagram of the ferroelectric liquid crystal panel used in the conventional example and the example. FIG. 14 is a schematic diagram of the optical system used for measuring the BV curve in the conventional example and the example. Figures 15(a) and 15(b) are graphs showing the memory effect of the rubbing cell, Figure 16 is a schematic diagram of the wedge-shaped cell used for color measurement, and Figure 17 is the rubbing cell and 60
Figure 18 is a graph plotting the measured values of cell thickness and brightness for an 80 degree evaporated cell, Figure 19 is a graph plotting the calculated value of pretilt angle and Δneff. This is the graph. 161...Glass substrate, 162...I
A layer having a TO layer and an Al2O3 oblique evaporation layer or a rubbed organic polymer film layer thereon, 163...
... Ferroelectric liquid crystal layer, 164 ... Spacer for adjusting cell thickness, 165 ... Vapor deposition direction,
Alternatively, it shows how to combine rubbing directions. Name of agent Patent attorney Toshio Nakao (1 person) Figure 1 Between IIIF [m5ec] Figure 1 Unexamined patent application (msec) Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 6 Δnd (β72) Figure 7 0.2 (140,60,F! 10
/, 2Δrtd (μm) Fig. 8 Bottom Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 13 / 3φ Fig. 14 Fig. 15 Time (rnsec) Thickness (μm)

Claims (2)

[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 applying means attached to the substrates so as to apply a voltage to the liquid crystal layer. 1. A ferroelectric liquid crystal panel characterized in that the orientation of ferroelectric liquid crystal is controlled by vapor-depositing silicon dioxide from an oblique direction with respect to a substrate in the panel. (2) A ferroelectric liquid crystal panel according to claim (1), wherein the ferroelectric liquid crystal panel has a cell thickness of 5 μm or less.