JPH0553117A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To improve a contrast and display grade. CONSTITUTION:This liquid crystal element has a chiral smectic liquid crystal 15 and a pair of substrates 11a, 11b which face each other by holding this liquid crystal 15 in-between, are formed with electrodes 12a, 12b for impressing voltages to the chiral smectic liquid crystal 15 on the respective opposite surface and are subjected to an orientation treatment to intersect the uniaxial orientation axes for orienting the liquid crystal 15 with each other at a prescribed angle. The above-mentioned element is specified to <=3.8 dielectric constant in the impression of the square waves of the chiral smectic liquid crystal 15 and has the orientation state of THETA<alpha+delta and delta<alpha in the relations among the pretilt angle alpha and cone angle THETA of the chiral smectic liquid crystal and the angle delta of inclination of the liquid crystal layer. The element exhibits at least two stable states in this orientation state and has the relation of THETA>thetaa>THETA/2 between the apparent tilt angle thetaa and the cone angle THETA.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal element used in a liquid crystal display element, a liquid crystal optical shutter or the like, particularly a ferroelectric liquid crystal element, and more specifically, a dielectric constant in a liquid crystal layer when a rectangular wave is applied is below a specific value. The present invention relates to a liquid crystal element having improved display characteristics.

[0002]

2. Description of the Related Art A display device of a type in which transmitted light rays are controlled by using a refractive index anisotropy of ferroelectric liquid crystal molecules in combination with a polarizing element has been proposed by Clark and Lagerwall ( JP-A-56-107216, U.S. Pat. No. 4,367,924.
No. etc.). This ferroelectric liquid crystal generally has a non-helical chiral smectic C phase (SmC ^* ) or H phase (SmH ^* ) in a specific temperature range, and in this state, it has a first phase in response to an applied electric field. Has an optical stable state and a second optical stable state, and has the property of maintaining that state when no electric field is applied, that is, bistability, and has a quick response to changes in the electric field. Therefore, it is expected to be widely used for high-speed and memory type display elements, and in particular, due to its function, application to a large-screen, high-definition display is expected.

Generally, in the case of a liquid crystal element utilizing the birefringence of liquid crystal, the transmittance under the crossed Nicols is expressed by the following equation (4).

[0004]

[Equation 4] During expression 4, I _O is the intensity of incident light, I is the transmitted light intensity, tilt angle of the apparent theta _a is defined below, [Delta] n is the refractive index anisotropy, d is the liquid crystal layer thickness and,, lambda Is the wavelength of the incident light. Apparent tilt angle θ _a in the aforementioned non-helical structure
Will appear as an angle in the average molecular axis direction of the twisted liquid crystal molecules in the first and second alignment states. According to Equation 4, the apparent tilt angle theta _a becomes the maximum transmittance when the angle of 22.5 °, the tilt angle theta _a apparent in the non-helical structure for realizing bistability in 22.5 ° It is necessary to be as close as possible.

However, the alignment method that has been used so far, in particular, the alignment method using a rubbing-treated polyimide film is applied to the ferroelectric liquid crystal having a non-helical structure and exhibiting the bistability, which was announced by Clark and Lagauall. When applied, it had the following problems.

That is, according to the experiments by the present inventors, an apparent tilt angle θ _a (two stable states) in _a ferroelectric liquid crystal having a non-helical structure obtained by orienting with a conventional rubbing-treated polyimide film was obtained. 1 / angle of the molecular axis of
It was found that 2) was smaller than the cone angle in the ferroelectric liquid crystal (angle Θ which is 1/2 of the apex angle of the triangular pyramid shown in FIG. 4 described later). In particular, the apparent tilt angle θ _a of _a ferroelectric liquid crystal having a non-helical structure obtained by orienting with a conventional rubbing-treated polyimide film is generally about 3 ° to 8 °, and the transmittance at that time is at most 3-5. It was about%.

Therefore, the present inventors have proposed a large apparent tilt angle θ _{a in} the non-helical structure of the chiral smectic liquid crystal.
In order to realize a display in which a high-contrast image is displayed, which is not sufficient, first of all, the following has been discovered, and the following will be explained.

That is, a chiral smectic liquid crystal,
Electrodes are formed on the opposing surfaces while holding the liquid crystal in between, and the opposing surfaces are each provided with an electrode for applying a voltage to the chiral smectic liquid crystal, and the uniaxial alignment axes for aligning the liquid crystal are at a predetermined angle from each other. In a liquid crystal element comprising a pair of substrates subjected to crossed alignment treatment, if the pre-tilt angle of the smectic liquid crystal element is α, the cone angle is Θ, and the tilt angle of the liquid crystal layer is δ, the smectic liquid crystal has the following structure. A liquid crystal element having an alignment state represented by Formula 5, wherein the liquid crystal in the alignment state exhibits at least two stable states, and the angle formed by the optical axes thereof is 1
If the liquid crystal device is characterized in that the apparent tilt angle θ _a that is / 2 and the cone angle Θ of the chiral smectic liquid crystal have the relationship of the following formula 6, a display that displays a high-contrast image is It became clear that it could be realized.

[0009]

[Equation 5]

[0010]

[Equation 6] Hereinafter, this will be sequentially described. Smectic liquid crystals generally have a layered structure, but S _A phase to S _C phase or S phase
_{When the} transition to the _C ^* phase occurs, the layer spacing shrinks, and as shown in FIG. 3, the layer 31 has a bent structure (ie, a chevron structure) at the center of the upper and lower substrates.

As shown in the figure, the bending direction is the orientation state (C which appears immediately after the transition from the high temperature phase to the S _C ^* phase).
The present inventors have found that there can be two cases, that is, in the case of the portion 32 of the (1 orientation state) and in the case of the portion 33 of the orientation state (C2 orientation state) that is mixedly present in the C1 orientation state when the temperature is further lowered. discovered. Furthermore, it was newly discovered that when a combination of a specific alignment film and a liquid crystal is used, the above-mentioned transition from the C1 alignment state to the C2 alignment state does not easily occur, and depending on the liquid crystal material, the C2 alignment state does not occur at all. It was discovered that the contrast of the C1 orientation is very high and the contrast of the C2 orientation is low when the relationship of Θ <α + δ is satisfied by using a high pretilt alignment film. Therefore, if a high pretilt alignment film is used as the display element, the entire screen is unified to the C1 alignment state, and the two states of high contrast are used as the two states of black and white display, it is expected that a display with higher quality than before can be obtained. It
The pretilt will be described below.

As described above, the C1 orientation is not generated.
It is concluded that the following conditions must be satisfied in order to realize the oriented state. That is, as shown in FIG. 4, the directors near the substrate in the C1 orientation and the C2 orientation are on the cone 41 shown in FIGS. 4 (a) and 4 (b), respectively. As is well known, the rubbing causes the liquid crystal molecules at the interface of the substrate to form an angle called pretilt with respect to the substrate, and the direction of the liquid crystal molecules heads toward the rubbing direction (direction of arrow A in FIG. 4). It is suitable for lifting (making the tip floated). From the above, the following expression 7 must be established among the cone angle Θ, the pretilt angle α and the layer tilt angle δ of the liquid crystal.

[0013]

[Equation 7] Therefore, the condition for producing the C1 orientation without causing the C2 orientation as described above is expressed by the following formula 8.

[0014]

[Equation 8] Furthermore, from a simple consideration of the torque that the interface molecules receive from the one position to the other position due to the electric field, the following formula 9 is obtained as a condition under which the interface molecules are likely to switch.

[0015]

[Equation 9] Therefore, in order to form the C1 orientation state more stably,
It is effective to satisfy the relationship of Expression 9 in addition to the expression.

As a result of further experiments under the conditions of the equations (8) and (9), the apparent tilt angle θ _a of the liquid crystal is also shown in the equation (8).
3 ° in the conventional case that does not satisfy the conditions of the formula and the formula 9
It is empirically that the relational expression of the following formula 10 holds between the cone angle Θ of the liquid crystal and 8 ° to 16 ° when the conditions of the formulas 8 and 9 are satisfied. Was obtained.

[0017]

[Equation 10] As described above, it has been clarified that a display in which a high-contrast image is displayed can be realized if the conditions of Expressions 8, 9, and 10 are satisfied.

Further, in order to stably form the C1 orientation state and obtain good orientation, the rubbing direction of the upper and lower substrates is set to 2 ° to.
It was found that cross rubbing shifted in the range of 25 ° (crossing angle) was also extremely effective.

[0019]

However, when a driving display is performed by applying an electric field using the display device using the liquid crystal element structure as described above, the contrast of the image is remarkably lowered, and particularly, the black display is performed. The present inventors have found that there is a case where the image becomes lighter and the contrast is remarkably lowered, resulting in poor display quality.

Therefore, an object of the present invention is to solve this problem, that is, to improve the contrast and display quality in a liquid crystal element using a chiral smectic liquid crystal.

[0021]

As a result of earnest research to solve the above-mentioned problems, the present inventor sets the dielectric constant of a chiral smectic liquid crystal molecule to a specific value or less when a rectangular wave is applied in the vertical component direction. It was discovered that the above-mentioned problems of the prior art can be solved and the display characteristics of the liquid crystal element can be remarkably improved.

That is, according to the present invention, the chiral smectic liquid crystal and the liquid crystal are opposed to each other with the liquid crystal held therebetween, and electrodes for applying a voltage to the chiral smectic liquid crystal are formed on the opposed surfaces, and the liquid crystal is aligned. In a liquid crystal element comprising a pair of substrates subjected to an alignment treatment in which uniaxial alignment axes for intersect at a predetermined angle,
The dielectric constant of a chiral smectic liquid crystal when a rectangular wave is applied satisfies the following formula 11, and the pretilt angle of the chiral smectic liquid crystal is α, the cone angle is Θ, and the tilt angle of the liquid crystal layer is δ.
If so, the chiral smectic liquid crystal has an orientation state represented by the following formula 12, and at least two stable states are exhibited in this orientation state, and an apparent tilt that is 1/2 of the angle formed by the optical axes thereof It is characterized in that the angle θ _a and the cone angle Θ have the relationship of the following Expression 13.
However, the crossing angle of the uniaxial orientation axis is preferably 2 ° to 25 °.

[0023]

[Equation 11]

[0024]

[Equation 12]

[0025]

[Equation 13] The subscript eff in the formula 11 is an abbreviation for effective, and means that it effectively contributes when a rectangular wave is applied.

[0026]

In the liquid crystal element using the chiral smectic liquid crystal, if the pretilt angle of the liquid crystal element is α, the cone angle is Θ, and the tilt angle of the liquid crystal layer is δ, the smectic liquid crystal has an alignment state represented by the above formula (12). And the orientation state exhibits at least two stable states, and the apparent tilt angle θ _a , which is 1/2 of the angle formed by the optical axes thereof, and the cone angle of the chiral smectic liquid crystal, As described above, a liquid crystal device characterized by having a relationship of (3) can realize a display in which a high-contrast image is displayed.

However, even in the case of the liquid crystal element having the above-mentioned relationship, when the display is performed by applying the electric field, the contrast of the image is remarkably lowered, and particularly, the black becomes pale and the display quality is deteriorated. It became clear that there is. The mechanism of the phenomenon of display quality deterioration due to the application of the electric field is still unknown, but it is presumed that it is due to the behavior described below.

That is, when a liquid crystal element using a chiral smectic liquid crystal is actually used as a display panel, an electric field is applied between the upper and lower substrates via the scan electrodes and the information electrodes arranged in a matrix on the upper and lower substrates. When actually displaying an image, for example, an electric field having a waveform as shown in FIG. 7 is applied, when performing a white display, a waveform 61 is applied, and when performing a black display, an electric field having a waveform as shown by a waveform 62 is applied. However, the electric fields necessary for displaying white and black on each matrix (intersection of each scanning electrode and information electrode) are applied only during the selection period of section 64 and section 65, respectively, and the other sections are rewritten to black and white. This is a non-selection period in which a weak electric field that does not reach the above is alternately applied in the positive and negative directions, and the electric field in the non-selection period is applied to each matrix for an overwhelmingly longer time than the electric field in the selection period. In this way, when a weak electric field that does not result in the inversion of liquid crystal molecules is applied to the liquid crystal in a positive and negative alternating manner, the liquid crystal molecules are instantly applied to the liquid crystal molecules at the moment when the electric field opposite to the spontaneous polarization of the liquid crystal molecules in one stable state is applied. Moves toward the other stable state and moves slightly on the cone 41 shown in FIG. 4 in the direction of inversion, but the original electric field of the opposite polarity is applied at the next moment. The behavior of returning to a stable state is repeated, resulting in the phenomenon that liquid crystal molecules fluctuate on the cone. Therefore, it is considered that when black display is performed, light leakage occurs, the black becomes pale, and the display quality deteriorates.

The inventors of the present invention have made investigations in order to solve the problem that the display quality is deteriorated as described above when a drive display is performed by applying an electric field in a liquid crystal element satisfying the expressions (12) and (13). As a result of repeated experiments, the value of the dielectric constant when applying a rectangular wave to the vertical component direction of the liquid crystal molecules in the liquid crystal element showed a correlation with the fluctuation of the liquid crystal molecules caused by applying an electric field to the liquid crystal element. It has been discovered that fluctuations of liquid crystal molecules are significantly reduced when the dielectric constant at time falls below a certain value.

At this time, the dielectric constant is mentioned as a physical property parameter that correlates with the fluctuation of the liquid crystal, and usually s
Since the dielectric constant measured by the in-wave is used, the present inventors first examined the correlation between the dielectric constant and the fluctuation by using the dielectric constant measured by the sin wave. However, it turned out that there was no correlation.

Then, next, with the hint that a rectangular wave is applied instead of a sin wave in an actual matrix panel, the present inventors defined the permittivity of rectangular wave application, and this is the dielectric constant of a sin wave. It was found to be essentially different from the rate and correlated with the above fluctuations.

This will be described in detail. First, a method of measuring the rejection wave dielectric constant will be described with reference to FIGS. The liquid crystal cell used for the measurement has an ITO film formed on a glass substrate, and a polyimide alignment film (Toray Industries LP
-64) was formed to a thickness of 50Å, a horizontally aligned cell was formed by rubbing treatment, and the liquid crystal composition was injected into the cell. FIG. 5 shows a measuring circuit, and FIG. 6 shows a waveform a of a voltage applied to the liquid crystal cell 51 and a voltage waveform b induced across the load resistance R _L (= 10 KΩ). The voltage waveform b is observed by an oscilloscope.

The rectangular wave permittivity is obtained by using the following equation (14).

[0034]

[Equation 14] Here, Q _t is the integrated value (total charge amount) of the voltage waveform b shown in FIG. 6, C is the capacitance of the cell, ε ₀ is the dielectric constant of the vacuum, and d
Is the cell thickness and S is the electrode area. It has been found that the dielectric constant of the rectangular wave defined in this way has a correlation with the value of fluctuation degree B _X described later. The details will be described in Examples.

The reason why the correlation with the fluctuation is the dielectric constant of a rectangular wave rather than a sin wave can be considered as follows.

The drive frequency range of the chiral smectic liquid crystal used in the present invention (frequency = 1 / 2ΔT from FIG. 6) is several kHz to several tens kHz, and at this frequency, the permittivity of sin wave has almost no frequency dependence. However, it has been obtained that the permittivity of the rectangular wave decreases as the frequency becomes higher and becomes smaller than the permittivity of the sin wave. In other words, in the case of the sin wave, the original behavior of the dielectric material is shown, whereas in the case of the rectangular wave, the interval Δ in FIG.
It can be explained that when T is short, the applied pulse ends before the charge / discharge current is fully attenuated, so that the higher the frequency becomes, the smaller the value of the rectangular wave dielectric constant becomes, and the smaller the dielectric constant of the sin wave becomes. it can.

Due to the essential difference between the two cases, it is considered that only the rectangular wave permittivity has a correlation with the fluctuation.

The condition for measuring the rectangular wave permittivity is ΔT = Δ
Tmin (minimum pulse width that can be driven by the drive waveform), E
(Electric field strength) = 3.79 V / μm.

The fluctuation degree B _X can be measured as follows. The chiral smectic liquid crystal element is arranged between the orthogonal crossed Nicols, and the waveform 6 in FIG.
The polarization axis is adjusted so that the stable state obtained when an electric field with a waveform such as 2 is applied is a dark field in the absence of an electric field, and optical is applied with Photomal (manufactured by Hamamatsu Photonics KK) while applying the electric field as described above. The response is detected, and the difference between the maximum transmitted light amount and the minimum transmitted light amount is defined as the fluctuation degree B _X. For example, in FIG.
When the drive waveform (black waveform) 62 is applied, the optical response waveform of the liquid crystal element due to Photomal becomes a waveform 63 in FIG. 7. The measurement condition of the fluctuation degree B _X in this case is exactly the same pulse width ΔT and electric field strength E as in the measurement of the rectangular wave permittivity.

[0040]

1 is a sectional view schematically showing a liquid crystal element according to an embodiment of the present invention. As shown in the figure, this liquid crystal element is opposed to a chiral smectic liquid crystal 15 with the liquid crystal 15 held in between, and electrodes 12a and 12b for applying a voltage to the chiral smectic liquid crystal on opposite surfaces thereof. And a pair of substrates 11a and 11b that have been subjected to an alignment treatment in which uniaxial alignment axes for aligning liquid crystals intersect each other at a predetermined angle.

The substrates 11a and 11b are made of glass plates, and are made of In ₂ O ₃ or ITO (Indium Ti), respectively.
n Oxide) and other transparent electrodes 12a and 12b. And, on it, S of 200-3000Å thickness
Insulating film 13a such as iO ₂ film, TiO ₂ film, Ta ₂ O ₅ film
13b and 50-1000 formed of polyimide
Å Thick orientation control films 14a and 14b are laminated respectively. Here, a thin film of tantalum oxide is formed on the glass substrates 11a and 11b provided with the transparent electrodes 12a and 12b by a sputtering method, and a polyamide made by Hitachi Chemical Co., Ltd. shown by the structural formula of FIG. 2 is formed thereon. 1% of acid LQ1802
The NMP solution is applied by a spinner and baked at 270 ° C. for 1 hour.

The alignment control films 14a and 14b have a crossing angle of 6 ° counterclockwise with respect to the alignment control film 14a on the upper side with respect to the alignment control film 14b on the upper side. Uniaxial alignment treatment to have
In addition, the rubbing process (direction of arrow A) is performed so that they are oriented in the same direction (direction A in FIG. 1). Hereinafter, the intersection angle will be defined in this way. The distance between the substrates 11a and 11b is sufficiently small to suppress the formation of the helical alignment structure of the chiral smectic liquid crystal 15, for example, 0.
It is set to 1 to 3 μm. Here, 1.2-1.3μ
m. This distance is held by a bead spacer 16 (silica beads, alumina beads, etc.) arranged between the substrates 11a and 11b.

The chiral smectic liquid crystal 15 has a bistable alignment state. 17a and 17b are polarizing plates.

In this liquid crystal element, the expressions (12) and (13) are satisfied.

The cone angle Θ, the tilt angle δ of the liquid crystal layer, the pretilt angle α, the apparent tilt angle θ _a , and the specific resistance ρ in the liquid crystal device having such a structure can be measured as follows. it can.

To measure the cone angle Θ, first ± 30
While applying AC (AC) of ± 50 V, 100 Hz between the upper and lower substrates of the liquid crystal element via the electrodes 14a and 14b, the liquid crystal element arranged between them is rotated in parallel with the polarizing plates 17a and 17b. At the same time, the first extinction position (the position where the transmittance is the lowest) and the second extinction position are obtained while detecting the optical response with Photomal (manufactured by Hamamatsu Photonisque Co., Ltd.). Then, the cone angle Θ is 1/2 of the angle from the first extinction position to the second extinction position at this time.

In order to measure the apparent tilt angle θ _a , first, a single pulse having a threshold value of the liquid crystal is applied, and then a liquid crystal element disposed between them is polarized under no electric field and under orthogonal crossed Nicols. The plate is rotated parallel to the plates 17a and 17b, and the first extinction position is obtained. Next, after applying a pulse having a polarity opposite to the one-shot pulse described above, the second extinction position is obtained under no electric field. The half of the angle from the first extinction position to the second extinction position at this time is defined as θ _a .

The tilt angle δ of the liquid crystal layer is measured by an X-ray analysis method using an X-ray analysis device RAD-IIB (45 KV, 30 mA).

The pretilt angle α is determined according to Jpn. J. App
l. Phys. vol19 (1980) NO. 10, S
It is determined according to the method (crystal rotation method) described in “Hort Notes 2013”. That is, for example, substrates rubbed in parallel and in opposite directions are bonded to each other to form a cell having a cell thickness of 20 μm,
If the measurement is performed by enclosing the liquid crystal (A) having the SmA phase in the range of 0 ° C., the polarized light that forms an angle of 45 ° with the rotation axis while rotating the liquid crystal cell in the plane perpendicular to the upper and lower substrates and including the alignment treatment axis. A helium-neon laser beam having a plane is irradiated from a direction perpendicular to the rotation axis, and the transmitted light intensity is measured by a photodiode through a polarizing plate having a transmission axis parallel to the incident polarization plane on the opposite side. Then, the angle formed by the center of the hyperbolic group of transmitted light intensity formed by the interference and the line perpendicular to the liquid crystal cell is φ, and the pretilt angle α is obtained by substituting it in the following expression (15).

[0050]

[Equation 15] The pretilt angle α of the liquid crystal element of this example was measured by this method and found to be 17 °. This liquid crystal element (cell) has a liquid crystal 15 that satisfies the formulas 12 and 13 above.
As mixed chiral smectic liquid crystals A to D containing phenylpyrimidines having various rectangular wave dielectric constants as main components
Was injected, and the rectangular wave permittivity and fluctuation degree B _X at 30 ° C. were measured for each. The results are shown in Table 1.
Examples 1 to 4 are shown below.

Next, as Comparative Example 1 into a cell having the same specifications as above, a chiral smectic liquid crystal containing phenylpyrimidine satisfying the above formulas 12 and 13 as a main component was injected, and a rectangular wave dielectric constant at 30 ° C. was injected. And fluctuation degree B _X were measured. The results are shown in Table 1.

As Examples 5 and 6, Comparative Example 1
The rectangular wave permittivity and fluctuation degree B _X at 50 ° C. and 55 ° C. of the liquid crystal device used in 1. were measured. This result is also shown in Table 1.
As shown in.

[0053]

[Table 1] As can be seen from Examples 1 to 4 and Comparative Example 1 in Table 1, only the liquid crystal (E) having a square wave dielectric constant at 30 ° C. of more than 3.8 out of the liquid crystals (A) to (E) fluctuates. The value of the degree B _X is dramatically large, and the fluctuation of liquid crystal molecules is large. Further, as can be seen from Examples 5 and 6 and Comparative Example 1, even in the liquid crystal (E) having a rectangular wave dielectric constant of more than 3.8 at 30 ° C. and large fluctuation of liquid crystal molecules (E), at 50 ° C. and 55 ° C. 3.8
It shows that the dielectric constant of the rectangular wave is less than 1, and the fluctuation of liquid crystal molecules is small.

From the above results, fluctuations of liquid crystal molecules can be suppressed and higher contrast can be obtained by setting the dielectric constant of the liquid crystal molecules in the liquid crystal element in the vertical component direction when a rectangular wave is applied to 3.8 or less. It can be seen that a liquid crystal element with high display quality can be obtained.

[0055]

As described above, according to the present invention, C
Since the liquid crystal having a low dielectric constant when a rectangular wave is applied to the vertical component direction of the liquid crystal molecules is used by utilizing the one-orientation state, it is possible to obtain a higher contrast image even during driving. The quality can be improved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a liquid crystal element according to an embodiment of the present invention.

2 is a structural formula of a polyamic acid of an orientation control film of the device of FIG.

FIG. 3 is an explanatory diagram for explaining a difference between two kinds of orientation states of C1 and C2.

FIG. 4 is an explanatory diagram showing a relationship among a cone angle, a pretilt angle, and a layer tilt angle in C1 and C2 orientations.

FIG. 5 is a measurement circuit diagram for explaining a principle of measuring a rectangular wave dielectric constant.

6 is a waveform diagram showing a waveform of a voltage applied to the liquid crystal cell of FIG. 5 and a voltage waveform induced across a load resistance.

FIG. 7 is a timing chart showing the relationship between the waveform of the electric field applied to the liquid crystal element, the optical response waveform measured by Photomal, and the drive waveform.

[Explanation of symbols]

15: chiral smectic liquid crystal, 12a, 12b: electrodes, 11a, 11b: substrate

Claims (2)

[Claims] 1. A chiral smectic liquid crystal and a liquid crystal which are opposed to each other while holding the liquid crystal therebetween, and electrodes for applying a voltage to the chiral smectic liquid crystal are respectively formed on the opposite surfaces, and the uniaxial liquid crystal is oriented. In a liquid crystal device having a pair of substrates whose organic alignment axes intersect each other at a predetermined angle or which have been subjected to parallel alignment treatment, the dielectric constant of a chiral smectic liquid crystal when a rectangular wave is applied is expressed by the following formula 1 And the pretilt angle of the chiral smectic liquid crystal is α, the cone angle is Θ, and the tilt angle of the liquid crystal layer is δ, the chiral smectic liquid crystal has an alignment state represented by the following formula 2 and Shows at least two stable states, and the apparent tilt angle θ _a , which is ½ of the angle formed by the optical axes thereof, and the cone angle Θ have the relationship of the following mathematical formula 3. A liquid crystal element characterized by the following. [Equation 1] [Equation 2] [Equation 3] 2. The intersection angle of the uniaxial orientation axes is 2 ° to 25.
The liquid crystal element according to claim 1, wherein the liquid crystal element has an angle of?