JP3060146B2 - Liquid crystal element and liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device used for a liquid crystal display device or a liquid crystal light shutter, and more particularly to a device using a ferroelectric liquid crystal and a liquid crystal display device using the device.

[0002]

2. Description of the Related Art Clark and Lagerwall have proposed a display device of a type that controls transmitted light in combination with a polarizing element utilizing the refractive index anisotropy of ferroelectric liquid crystal molecules. (JP-A-56-107216, U.S. Pat.
No. 4 specification). This ferroelectric liquid crystal generally has a chiral smectic C phase (SmC ^* ) or H phase (SmH ^* ) having a non-helical structure in a specific temperature range, and in this state, the first phase responds to an applied electric field. Has the property of taking either the optically stable state or the second optically stable state and maintaining the state when no electric field is applied, that is, has bistable stability, and has a quick response to a change in the electric field. Therefore, it is expected to be widely used for high-speed and storage type display elements, and in particular, its function is expected to be applied to a large screen and high definition display.

In general, in the case of a liquid crystal element utilizing birefringence of liquid crystal, the transmittance under crossed Nicols is I / I _o = sin4θ _a sin ² (Δnd / λ) π (where _Io is incident light) intensity, 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 thickness of the liquid crystal layer, and λ is the wavelength of the incident light. ). Tilt angle theta _a apparent in the above-mentioned non-helical structure would first and appears as a angle between the average molecular axis directions of liquid crystal molecules in a twisted alignment in a second orientation state. According to the above equation, the apparent tilt angle θ _a is 2
The maximum transmittance is obtained at an angle of 2.5 °, and the apparent tilt angle θa in _a non-helical structure that realizes bistability is 22.
It is desirable to be as close as possible to 5 °.

However, the alignment method used so far, in particular, the alignment method using a rubbed polyimide film, is compared with the above-mentioned non-helical ferroelectric liquid crystal having a bistable structure disclosed by Clark and Lagerwal. When applied, it has the following problems.

That is, the apparent tilt angle θ _a (1/2 of the angle formed by the molecular axes of the two stable states) in a non-helical ferroelectric liquid crystal obtained by orientation using a conventional rubbed polyimide film. ) Is smaller than the cone angle of the ferroelectric liquid crystal (Θ of the apex angle of the triangular pyramid shown in FIG. 3). In particular, the apparent tilt angle θa of _a ferroelectric liquid crystal having a non-helical structure obtained by orientation with a conventional rubbed polyimide film is generally about 3 ° to 8 °, and the transmittance at that time is at most 3 to
It was about 5%.

However, since then, the following has been found in order to realize a display that produces _a large apparent tilt angle θa in the non-helical structure of the chiral smectic liquid crystal and displays a high-contrast image.

That is, a chiral smectic liquid crystal, an electrode for holding the liquid crystal therebetween and facing each other, and an electrode for applying a voltage to the liquid crystal are formed on the facing surfaces thereof, and a uniaxial alignment for aligning the liquid crystal. In a liquid crystal device comprising a pair of substrates subjected to an alignment process whose axes cross each other at a predetermined angle, the pretilt angle of the smectic liquid crystal device is α, the cone angle is Θ, the tilt angle of the liquid crystal layer (the liquid crystal layer and If the angle formed with the substrate normal is δ, the smectic liquid crystal is a liquid crystal element having an alignment state represented by Θ <α + δ and δ <α, and the liquid crystal in the alignment state has at least two stable states. shows a state, the liquid crystal device having a tilt angle of the apparent theta _a is ½ of the angle between their optical axes and said chiral smectic liquid crystal cone angle theta _{is, Θ> θ a> Θ /} 2 in relation Then, it became clear that a display that displays a high-contrast image can be realized.

The outline will be described below.

The smectic liquid crystal generally has a layered structure, but when the phase transitions from the SmA phase to the SmC phase or SmC ^* phase, the interval between the layers is shortened. Therefore, as shown in FIG. Takes a bent structure (chevron structure). As shown in the figure, the direction of bending is in the alignment state (C1 alignment state) 32 immediately after the transition from the high temperature phase to the SmC ^* phase, and in the alignment state that appears in the C1 alignment state when the temperature is further lowered. There are two cases in the part 33 of (C2 orientation state). Thereafter, when a combination of an alignment film having a specific high pretilt and a liquid crystal is used, the above-mentioned C1 → C2 transition is unlikely to occur, and depending on the liquid crystal material, no C2 alignment state is generated. In addition to the two low-contrast stable states in which the director of the liquid crystal is twisted between the upper and lower substrates (hereinafter referred to as a splay state), another two high-contrast stable states (hereinafter referred to as a uniform state) Was found to appear.

[0010] These states transit to each other when an electric field is applied. When a weak positive and negative pulse electric field is applied, a transition between the spray 2 states occurs, and when a strong positive and negative pulse electric field is applied, a transition between the uniform 2 states occurs.

When the uniform 2 state is used, a display device which is brighter and has higher contrast than the conventional one can be realized.

Therefore, the entire screen as a display element is unified into the C1 alignment state, and the high contrast 2 within the C1 alignment state.
If the states are used as two states of black-and-white display, it is expected that a display with higher quality than before can be realized.

[0013] As described above, the C1
In order to realize the orientation state, it is necessary to satisfy the following conditions.

That is, as shown in FIG.
The directors near the substrate in two orientations are shown in FIG.
It is on the cone 41 of (a) and (b). As is well known, rubbing causes the liquid crystal molecules at the substrate interface to
An angle called a pretilt is formed with respect to the substrate, and the direction is a direction in which the liquid crystal molecules hold their heads toward the rubbing direction (A direction in FIG. 3) (the tip becomes a floating shape). From the above, the relationship of Θ + δ> α for C1 orientation and Θ−δ> α for C1 orientation must be established among the cone angle Θ, the pretilt angle α, and the layer tilt angle δ of the liquid crystal.

Therefore, the condition for generating the C1 orientation without generating the C2 orientation is Θ−δ <α, that is, Θ <α + δ (I).

Further, from a simple consideration of the torque that is applied to the switching of the interface molecules from one position to the other position by an electric field, α> δ (II) is obtained as a condition under which the switching of the interface molecules is likely to occur.

Therefore, in order to more stably form the C1 orientation state, it is effective to satisfy the relationship of the formula (II) in addition to the relationship of the formula (I).

As a result of further experiments under the conditions of the formulas (I) and (II), the apparent tilt angle θ _a of the liquid crystal is
From about 3 ° to 8 ° in the case of the conventional liquid crystal element which does not satisfy the conditions of the formulas (I) and (II), to about 8 ° to 16 ° in the case of satisfying the conditions of the formulas (I) and (II) Increase,
It has been empirically obtained that a relational expression of Θ> θ _a > Θ / 2 (III) holds between the liquid crystal and the cone angle の of the liquid crystal.

As described above, (I), (II) and (I)
It has been clarified that a display capable of displaying a high-contrast image can be realized if the condition of the formula II) is satisfied.

In order to stably form the C1 alignment state and obtain good alignment, the rubbing directions of the upper and lower substrates are set to 1 ° to 25 °.
Cross rubbing shifted in the range of ° (intersection angle) is also extremely effective.

By the way, a display device using a chiral smectic liquid crystal element is a display device capable of realizing a larger screen and a higher definition than a conventional CRT or TN type liquid crystal display. As the definition becomes higher, the frame frequency (single screen forming frequency) becomes lower. Therefore, the screen rewriting speed, smooth scrolling on character editing and graphics screens, and moving image display speed such as cursor movement are performed. However, there was a problem that the operation was slow. A solution to this problem is disclosed in JP-A-60-3
No. 1120, JP-A-1-140198 and the like.

That is, a display panel in which scanning electrodes and information electrodes are arranged in a matrix, means for selecting all or a predetermined number of scanning electrodes (the case of selecting by this means is referred to as whole writing), and all or a predetermined number of scanning electrodes Means for partially selecting one of the above (a case of selecting by this means is referred to as partial writing). This enables high-speed display by performing partial moving image display by partial writing, and achieves both partial writing and full-surface writing.

As described above, the above (I) and (II)
It was also found that driving a liquid crystal element satisfying the conditions of the formula (III) with a display device capable of partial writing described above can realize a high-contrast image on a large screen and a high definition display at high speed.

As described above, the ferroelectric liquid crystal potentially has extremely excellent characteristics, and by utilizing such characteristics, considerably solves many problems of the conventional TN type device. Substantial improvements have been made, and in particular, applications to high-speed optical shutters and high-density large-screen displays are expected, and extensive research has been conducted. However, the ferroelectric liquid crystal devices developed up to now have sufficient characteristics to be used as liquid crystal devices in the operable temperature range, the temperature dependence of response speed, low-temperature storage performance, impact resistance, etc. There were some aspects that were hard to say.

[0025]

The ferroelectric liquid crystal has poor fluidity compared to a nematic liquid crystal in a temperature range in which the ferroelectric liquid crystal is used because of having a clear layer structure. Therefore,
It has relatively fragile properties against stress from the outside of the cell, for example, impact force and strain force, and generates zigzag defects in which C1 orientation and C2 orientation coexist for mild impact. On the other hand, the layer structure itself is disturbed, and typically generates a sanded texture. The occurrence of a sanded texture due to an impact force is disclosed in, for example, US Pat. No. 4,674,839 to Tsuboyama et al. Generally, the anti-impact performance tends to deteriorate at a low temperature at which the viscosity of the liquid crystal increases and the fluidity of the liquid crystal becomes poorer, and becomes a serious problem when transported by an aircraft or the like.

The lower limit temperature of the chiral smectic C phase, that is, the phase transition temperature (Mp) to another liquid crystal phase or crystal phase
Essentially determines the low-temperature storage performance, but has excellent overall liquid crystal composition such as high response and low response speed, which shows good image quality over a wide temperature range including room temperature. The Mp of the product is set in a sufficiently low temperature range (for example,-
At present, it is quite difficult to lower the temperature to 20 ° C. or less. Normally, Mp often takes a supercooled state during the temperature drop process, but it has been empirically found that there is a large difference in the stability of the supercooled state in the cell depending on the orientation state.

Accordingly, it is an object of the present invention to provide a liquid crystal element and a liquid crystal display device which are excellent in impact resistance performance, especially in low temperature impact performance. Another object of the present invention is to provide a liquid crystal element and a liquid crystal display device which are excellent in low-temperature storage performance utilizing a supercooled state.

[0028]

Means and Action for Solving the Problems The present inventors have
As a result of intensive studies to solve the above problems, the chiral smectic C phase is given a special orientation state in the low temperature range, thereby improving the impact resistance at low temperatures and improving the low temperature storage performance by supercooling. I found something.

That is, the present invention relates to a chiral smectic liquid crystal, and a uniaxial alignment for orienting the liquid crystal, wherein electrodes for applying a voltage to the liquid crystal are formed on opposite surfaces of the liquid crystal, respectively. A liquid crystal device comprising a pair of substrates whose axes are parallel to each other or intersect at a predetermined angle and are subjected to an alignment process, wherein the chiral smectic C
In a low-temperature region with a phase, in the absence of an electric field, the liquid crystal molecular axis is substantially the same as the central axis direction of the alignment treatment, and the liquid crystal molecules have only one darkest optical axis when sandwiched between crossed Nicol polarizers (low-temperature pseudo-state). (Smectic A alignment state).

Further, the present invention is characterized in that the above-mentioned alignment state (low-temperature pseudo-smectic A alignment state) is an alignment state generated in a temperature range lower than a temperature range in which two different alignment states are generated in a state where no electric field is applied. The above liquid crystal element.

In the device of the present invention, in order to realize high contrast, the chiral smectic liquid crystal and the pretilt angle of the liquid crystal device near room temperature are α, the cone angle is Θ, and the tilt angle of the liquid crystal layer (layer and substrate method). Assuming that the angle between the lines is δ, the chiral smectic liquid crystal shows an alignment state represented by Θ <α + δ and δ <α (1), and shows at least two stable states in this alignment state. preferred tilt angle theta _a and the cone angle theta apparent is 1/2 of the angle of the shaft has a relationship _{Θ> θ a> Θ / 2} (2) is.

In order to stably form the C1 alignment state and obtain good alignment, the crossing angle of the uniaxial alignment axis is set to 0.
It is preferably between 25 and 25 degrees.

Further, as a characteristic useful for improving the uniform alignment property, in the vicinity of the upper limit temperature of the chiral smectic C phase, in the absence of an electric field, the liquid crystal molecular axis is made substantially the same as the direction of the central axis of the alignment treatment. In the case of having an alignment state having only one darkest optical axis (high-temperature pseudo-smectic A alignment state).

In addition, good display characteristics near room temperature are maintained, and the above-mentioned “low temperature pseudo smectic A alignment state” is maintained at a low temperature.
A useful condition for having a displacement angle is that the inclination angle δ of the layer has a displacement point (maximum value of δ) that increases with a decrease in temperature and then decreases. Further, in order to effectively improve the temperature dependence of the driving characteristics near room temperature, the displacement point of δ is 10 ° C. or more, more preferably 25 ° C.
Desirably, it is at a temperature of at least ℃.

Further, the present invention provides a liquid crystal display device provided with a drive circuit for the liquid crystal element and a light source.

As a condition for the occurrence of the "low temperature pseudo-smectic A orientation state", it seems necessary to adopt a layer structure close to the bookshelf state in which the inclination angle δ of the layer is reduced to some extent. Also, the size of the cone angle Θ at this time is often smaller than the value at room temperature. However, even in the same liquid crystal composition, there is a difference in the temperature range in which the “low temperature pseudo-smectic A alignment state” appears due to the difference in the alignment treatment of the liquid crystal element. In general, when the pretilt of the element is high, the appearance temperature range seems to appear from a slightly higher temperature side. In addition, the magnitude of the tilt angle δ of the layer when the “low temperature pseudo smectic A alignment state” starts to appear also seems to be changed by the influence of the pretilt angle α of the liquid crystal element, the cone angle 液晶 of the liquid crystal, the viscosity, and the like. Although it is not possible to make a clear numerical value, it is empirically about 6 ° or less.

Further, when the pretilt angle of the liquid crystal element is large to some extent and the above-mentioned C1 uniform alignment state is obtained,
In the vicinity of the maximum temperature of the chiral smectic C phase, a “high temperature pseudo smectic A orientation state” is often taken. The difference between the “high-temperature pseudo-smectic A alignment state” and the “low-temperature pseudo-smectic A alignment state” is indistinguishable by visual observation, but is large when an electric field is applied to switch the liquid crystal and Θ is measured. Differences were noted. In the "high temperature pseudo-smectic A alignment state", when the application of the electric field is stopped, the movement of the liquid crystal molecule axis (optical axis) from one stable state to the alignment processing center axis occurs at a speed of several msec level, and the memory property Although it cannot be said that there is a state, in the "low temperature pseudo-smectic A alignment state", the above-mentioned movement of the liquid crystal molecular axis occurs in the order of 0.1 to several tens of seconds, and the memory state is obtained within this time. The behavior when the liquid crystal molecular axis (optical axis) moves from one stable state switched by this electric field (and the angle from the central axis of the alignment process to Θ) to the central axis of the alignment process depends on the smectic layer forming direction. (Perpendicular to the central axis direction of the alignment treatment).

This “low temperature pseudo smectic A alignment state”
It was confirmed by X-ray diffraction experiments that, first, the impact resistance at low temperatures was dramatically improved, secondly, the supercooled state was easily obtained, and the orientation was not disturbed by crystallization. Was. FIG. 8 shows a profile of the diffraction intensity in the X-ray diffraction pattern.

This is a rocking curve of a diffraction pattern obtained by scanning with respect to the θ axis while fixing 2θ to 3.0 ° (corresponding to a layer interval of 300 nm under black conditions) during measurement. The sharpness of the peak seen on the diffraction pattern is
Correlation length of layer structure
th) is long, and conversely, if the peak is broad, it indicates that the correlation length is short. According to FIG. 8, focusing on the peak shape in the SmC ^* phase, the peak at 10 to 50 ° C. is −10 ° C.
Has a sharper shape than the peak at. The clear reason for this experimental result is not yet clear, but it is presumed that it is mainly due to the increased flexibility of the layer structure.

According to the study of the present inventors, as means for adjusting the magnitude of the tilt angle δ of the layer and the temperature characteristics, the skeleton structure of the constituent compounds of the liquid crystal composition, the length of the side chain, and the distance between the components. Are generally compatible with each other.
In many cases, a kind of liquid crystal compound that expands the temperature range of mA greatly changes the temperature characteristic of δ.

FIG. 1 schematically shows a preferred example of the liquid crystal element of the present invention. In FIG. 1, reference numerals 11a and 11b denote In ₂ O ₃ and ITO (Indium Tin Oxi), respectively.
de) or the like (glass plate) covered with transparent electrodes 12a and 12b, on which insulating films 13a and 13b (SiO ₂ film, TiO ₂ film, Ta ₂ O ₅ film, etc.) ) And the general formula

[0042]

Embedded image The alignment control films 14a and 14b each formed of polyimide and having a thickness of 50 to 1000 mm are laminated. The alignment control films 14a and 14b have an alignment direction of the lower alignment film 14a.
The upper alignment film 14b performs a uniaxial alignment process with a crossing angle of 0 to 25 ° counterclockwise (or clockwise) as viewed from the upper alignment film 14a, and the same direction (arrow A in FIG. 1). Direction). In the following, the intersection angle is defined as described above.

A chiral smectic liquid crystal 15 is disposed between the substrates 11a and 11b.
Is set to a distance (for example, 0.1 to 3 μm) that is small enough to suppress the formation of a helical arrangement structure of the chiral smectic liquid crystal 15, and the chiral smectic liquid crystal 15 has a bistable alignment state. . The sufficiently small distance described above is maintained by a bead spacer 16 (such as silica beads or alumina beads) disposed between the substrates 11a and 11b. 17a and 17b are polarizing plates.

In the case where a simple matrix display device as described above is formed by using an element in which the ferroelectric liquid crystal layer is sandwiched between a pair of substrates, for example, JP-A-59-193426 and JP-A-59-193427. JP-A-60-1560
No. 46, Japanese Patent Application Laid-Open No. 60-156047 and the like can be applied.

FIG. 4 is an example of a waveform diagram of the driving method. FIG. 5 is a plan view of a ferroelectric liquid crystal panel on which the matrix electrodes used in the present invention are arranged. In the liquid crystal panel 51 of FIG. 5, the scanning lines of the scanning electrode group 52 and the data lines of the information electrode group 53 are wired so as to intersect each other, and a ferroelectric material is provided between the scanning line and the data line at the intersection. Liquid crystal is arranged.

By using the liquid crystal element of the present invention in a display panel section and employing a data synchronization format based on a SYNC signal and a data format of image information having scanning line address information shown in FIG. 6 and FIG. To achieve.

The generation of image information is performed by the graphics controller 102 on the main unit side, and is transferred to the display panel 103 in accordance with the signal transfer means shown in FIGS. The graphics controller 102 includes a central processing unit (hereinafter referred to as “GCPU”) 112 and a VRA
M (memory for storing image information) 114 as a core and host CP
It manages and communicates image information between the U 113 and the liquid crystal display device 101, and the control method is mainly realized on the graphics controller 102.

A light source is arranged on the back of the display panel.

The cone angle Θ, the apparent tilt angle θ _a , the tilt angle δ of the liquid crystal layer, and the pretilt angle α in the liquid crystal device according to the present invention can be measured as follows.

Measurement of Cone Angle Θ While applying an AC (alternating current) of ± 30 to ± 50 V, 1 to 100 Hz between the upper and lower substrates of the liquid crystal element through electrodes, the liquid crystal element arranged between and under the orthogonal crossed Nicols is applied. The first extinction position (the position where the transmittance becomes lowest) and the second extinction position are determined while detecting the optical response with Photomaru (manufactured by Hamamatsu Photonics KK) at the same time as rotating the polarizing plate in parallel. . Then, 1/2 of the angle from the first extinction position to the second extinction position at this time is defined as a cone angle Θ.

[0051] After the application of a single pulse of measuring the liquid crystal of the threshold value of the tilt angle θ _a apparent, no electric field under,
In addition, under the orthogonal crossed Nicols, the liquid crystal element disposed therebetween is rotated in parallel with the polarizing plate to obtain the first extinction position. Next, after applying a pulse having a polarity opposite to that of the above-mentioned single pulse, a second extinction position is obtained without an electric field. The first tilt angle theta _a apparent half angle from the extinction position to a second extinction position at this time.

Measurement of the tilt angle δ of the liquid crystal layer Basically, a method performed by Clark and Lager Wall (Japan Display '86, Sep. 3).
0 to Oct. 2, 1986.456-458) or the method of Ouchi et al. (JJAP, 27 (5) (19)
88) Measured in the same manner as in 725 to 728).
The measuring device used was a rotating cathode type X-ray diffractometer (manufactured by MAC Science), and a microsheet (80 μm thick) manufactured by Corning was used for the substrate in order to reduce the absorption of X-rays into the glass substrate of the liquid crystal cell.

Measurement of pretilt angle α J. A. P. 19 (1980) NO. 10 Sho
It was determined according to the method described in rt Notes 2013 (crystal rotation method).

That is, the rubbed substrates were bonded in parallel and in opposite directions to form a cell having a cell gap of 20 μm, and a compound represented by the following structural formula was added to a ferroelectric liquid crystal CS-1014 manufactured by Chisso Corporation. A mixture mixed at a ratio of 20% was injected as a standard liquid crystal and measured.

[0055]

Embedded image

Incidentally, the mixed liquid crystal composition was prepared as follows.
Shows the SmA phase at 55 ° C.

The measurement method is as follows. While rotating the liquid crystal cell in a plane perpendicular to the upper and lower substrates and including the alignment processing axis, the rotation axis is set to 45 degrees.
A helium-neon laser beam with a polarization plane at an angle of ° is irradiated from the direction perpendicular to the rotation axis, and the opposite side is used to reduce the transmitted light intensity with a photodiode through a polarizing plate with a transmission axis parallel to the incident polarization plane. It was measured.

The angle between the center angle of the group of hyperbolas of transmitted light intensity generated by interference and a line perpendicular to the liquid crystal cell is φ
_The pretilt angle α was determined by substituting _x into the following equation.

[0059]

(Equation 1)

[0060] n _o: ordinary refractive index n _e: extraordinary refractive index

[0061]

EXAMPLES and COMPARATIVE EXAMPLES The liquid crystal compounds constituting the liquid crystal composition used in this experiment are shown below.

[0062]

Embedded image

[0063]

Embedded image

Table 1 below shows specific examples of the liquid crystal compound represented by the general formula (4).

The alphabets in the table represent side groups or cyclic groups shown below.

Met = CH ₃ , hep = C ₇ H ₁₅ , trd
_{= C 13 H 27, eth =} C 2 H 5, oct = C 8 H 17, t
_{et = C 14 H 29, pro} = C 3 H 7, non = C
_{9 H 19, ped = C 15} H 31, but = C 4 H 9, dec
= C ₁₀ H ₂₁ , hexd = C ₁₆ H ₃₃ , pen = C ₅ H ₁₁ ,
und = C ₁₁ H ₂₃ , hepd = C ₁₇ H ₃₅ , hex = C _{6
H 13, dod = C 12 H} 25, ocd = C 18 H 37, 2mb
= 2-methyl-Butyl,

[0067]

Embedded image

[0068]

[Table 1]

Table 2 below shows specific examples of the liquid crystal compound represented by the general formula (5).

The alphabets in the table represent side groups or cyclic groups shown below.

Met = CH ₃ , hep = C ₇ H ₁₅ , trt
_{= C 13 H 27, eth =} C 2 H 5, oct = C 8 H 17, t
_{et = C 14 H 29, pro} = C 3 H 7, non = C
_{9 H 19, ped = C 15} H 31, but = C 4 H 9, dec
= C ₁₀ H ₂₁ , hexd = C ₁₆ H ₃₃ , pen = C ₅ H ₁₁ ,
und = C ₁₁ H ₂₃ , hepd = C ₁₇ H ₃₅ , hex = C _{6
H 13, dod = C 12 H} 25, ocd = C 18 H 37, 2mb
= 2-methyl-Butyl,

[0072]

Embedded image

[0073]

[Table 2]

<Examples> The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

Two diagonal 14 inch, 1.1 mm thick glass plates were prepared for a pair of substrates, and ITO (indium tin oxide) transparent with side metal (molybdenum) was provided on each glass plate. A stripe electrode was formed, and a tantalum oxide film was formed thereon as a transparent dielectric film by sputtering at a thickness of 1500 °.

On this tantalum oxide film, LQ-1802
(Made by Hitachi Chemical Co., Ltd.), LP-64 (made by Toray Industries, Inc.),
An NMP solution of a polyimide precursor solution such as RN-305 (manufactured by Nissan Chemical Co., Ltd.) is applied by a printing method, and 200 to 2
By baking at 70 ° C., a polyimide alignment film having a thickness of 100 to 300 ° was formed. Rubbing treatment with an acetate flocking cloth (uniaxial orientation treatment)
Was given. The pretilt angle was adjusted by changing the rubbing cloth, the rotation speed, the rubbing strength by changing the glass substrate feeding speed, and the combination of various polyimide alignment films.

Thereafter, epoxy resin adhesive particles having an average particle size of 5.5 μm (trade name: Trepearl; manufactured by Toray Industries, Inc.) were distributed on one substrate by a Nordson electrostatic spraying method at a distribution density of 50 particles / mm ^2. And sprayed. On another substrate, silica microbeads having an average particle size of 1.2 μm were sprayed at a distribution density of 300 / mm ² by a Nordson electrostatic spraying method.

Next, a liquid adhesive (trade name: Struct Bond; manufactured by Mitsui Toatsu Chemicals, Inc.) as a sealing member
Was applied by printing in a film thickness of 6 μm.

Next, the two glass plates were bonded together so that the uniaxial orientation axis was counterclockwise at a crossing angle of 0 to 10 ° and in the same direction, and 2.8 kg / cm ² at a temperature of 70 ° C. Pressure bonding by applying pressure for 5 minutes, and
While applying a pressure of 0.63 kg / cm ² at a temperature of
The two adhesives were cured for 4 hours to form a cell.

Thereafter, the pressure in the liquid crystal cell was reduced to 10 ⁻⁴ atm, and ferroelectric liquid crystals A to H, ZLI-3233 (Merck, Inc.) containing a liquid crystal compound having the above structure as a main component. Co., Ltd.) and CS-1014 (Chisso Corporation)
Was injected in the isotropic phase. The liquid crystal ratios of the liquid crystals A to H are different from each other as appropriate. The constituent components and the mixing ratio of the liquid crystal G and the liquid crystal H are shown below.

[0081]

Embedded image

[0082]

Embedded image

[0083]

Embedded image

[0084]

Embedded image

Thereafter, the mixture was cooled to 30 ° C. to form a chiral smectic C phase through the cholesteric phase and the smectic A phase or through the smectic A phase.

The phase transition temperature of these liquid crystal compositions was 30 ° C.
Table 3 shows the magnitude (Ps) of the spontaneous polarization and the cone angle (Θ), and Table 4 shows the temperature characteristics of the inclination angle (δ) of the layer.

[0087]

[Table 3]

Cry; crystalline phase or higher smectic phase S ^* _C ; chiral smectic C phase S _A ; smectic A phase Ch; cholesteric phase Iso; isotropic phase

[0089]

[Table 4]

Using the liquid crystal element thus prepared, an impact durability test was performed at 0 ° C. using a drop durability tester (DT-50: manufactured by Yoshida Seiki). At this time, a drop impact of 20 G (G: gravitational acceleration of 9.8 m / sec ² ) is 80
It was observed whether or not the orientation of the cell changed every time the G was increased by 10G.

Table 5 shows the results.

[0092]

[Table 5]

From the above results, chiral smectic C
Examples 1-1 to 1-7 according to the present invention having a pseudo-smectic A orientation state in the low-temperature region of the phase are 0 in comparison with Comparative Examples 1-1 to 1-3 having no low-temperature pseudo-smectic A orientation state. A large difference was observed in the impact test at ° C., and the element had good impact resistance performance.

When the orientation state of the above-mentioned element was maintained at -20 ° C. for 100 hours, the orientation states of the elements of Examples 1-1 to 1-7 according to the present invention did not significantly change. However, in the devices of Comparative Examples 1-1 to 1-3 having no low-temperature pseudo-smectic A alignment state, severe disorder of the alignment state which was considered to be due to crystallization was observed. Thus, the element having the low-temperature pseudo-smectic A orientation state more stably takes the supercooled state, and the low-temperature storage performance is improved as compared with the element having no low-temperature pseudo-smectic A orientation state.

Table 6 shows the results of the impact durability test at -5 ° C. in the same manner as described above.

[0096]

[Table 6]

From the above results, chiral smectic C
Examples 2-1 to 2-7 according to the present invention having a pseudo-smectic A orientation state in the low-temperature region of the phase are − in comparison with Comparative Examples 2-1 and 2-2 having no low-temperature pseudo-smectic A orientation state. In the 5 ° C. impact test, a large difference was observed.
The element has good impact resistance.

Next, LQ-1 was used to form a polyimide alignment film.
Using a liquid crystal element manufactured in the same manner except that LP-64 (manufactured by Toray Industries, Inc.) was used instead of 802, an impact durability test at −5 ° C. was performed in the same manner as above. Table 7 shows the results.

[0099]

[Table 7]

From the above results, chiral smectic C
Examples 3-1 to 3-5 based on the present invention having a pseudo-smectic A orientation state in the low-temperature region of the phase are − in comparison with Comparative Examples 3-1 and 3-2 having no low-temperature pseudo-smectic A orientation state. In the 5 ° C. impact test, a large difference was observed.
The element has good impact resistance.

[0101]

As described above, the device having the pseudo-smectic A orientation state in the low temperature region of the chiral smectic C phase of the present invention has a better impact resistance than the device having no low-temperature pseudo-smectic A orientation state. In addition to being excellent, there is an effect that the supercooled state is more stably taken and the low-temperature storage performance is improved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one example of a liquid crystal element of the present invention.

FIG. 2 is an explanatory diagram showing C1 and C2 orientations.

FIG. 3 is an explanatory diagram showing a relationship among a cone angle, a pretilt angle, and a layer inclination angle in C1 and C2 orientations.

FIG. 4 is a timing chart showing driving waveforms applied to the liquid crystal element of FIG.

FIG. 5 is a plan view of a liquid crystal panel on which matrix electrodes are arranged.

FIG. 6 is a block diagram showing a liquid crystal display device and a graphics controller of the present invention.

FIG. 7 is a timing chart of image information communication between the liquid crystal display device of the present invention and a graphics controller.

FIG. 8 is a diagram showing a difference in an X-ray diffraction pattern between an SmC ^* phase and a pseudo SmA phase.

[Explanation of symbols]

 11a, 11b Substrate 12a, 12b Transparent electrode 13a, 13b Insulating film 14a, 14b Alignment control film 15 Chiral smectic liquid crystal 16 Bead spacer 17a, 17b Polarizing plate 31 Liquid crystal layer 32 C1 alignment 33 C2 alignment 41 Cone 51 Liquid crystal panel 52 Scanning electrode group 53 Information electrode group 101 Ferroelectric liquid crystal display device 102 Graphics controller 103 Display panel 104 Scan line drive circuit 105 Information line drive circuit 106 Decoder 107 Scan signal generation circuit 108 Shift register 109 Line memory 110 Information signal generation circuit 111 Drive control circuit 112 GCPU 113 Host CPU 114 VRAM

Continuation of the front page (56) References JP-A-61-161123 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1337 510 G02F 1/141

Claims (10)

(57) [Claims] An electrode for applying a voltage to the liquid crystal is formed on each of opposing surfaces of the chiral smectic liquid crystal, and a uniaxial alignment axis for aligning the liquid crystal is parallel or opposite. A liquid crystal device comprising a pair of substrates that have been subjected to an alignment process crossing each other at a predetermined angle, and in a low-temperature region where a chiral smectic C phase is present, an average molecular axis of liquid crystal molecules is substantially aligned in a state where no electric field is applied. A liquid crystal element having an alignment state having only one darkest optical axis when held between crossed Nicol polarizers in the same direction as the processing central axis direction. 2. The liquid crystal device according to claim 1, wherein the alignment state is an alignment state generated in a temperature region lower than a temperature region in which two different alignment states are generated in a state where no electric field is applied. 3. A chiral smectic liquid crystal and a liquid crystal element thereof, where α is a pretilt angle near room temperature, Θ is a cone angle, and δ is a tilt angle of a liquid crystal layer, the chiral smectic liquid crystal is represented by the following formula (1). Orientation state,
And exhibits at least two stable states in this alignment state claim 1 in which the tilt angle theta _a and the cone angle Θ of the apparent one-half of the angle between their optical axes have the following relationship (2) Or the liquid crystal element according to 2. Θ <α + δ and δ <α (1) Θ> θ _a > Θ / 2 (2) 4. An intersection angle of the uniaxial orientation axis is 0 ° to 25 °.
The liquid crystal device according to claim 1, wherein the angle is °. 5. In the vicinity of the upper limit temperature of the chiral smectic C phase, in the absence of an electric field, the liquid crystal molecular axis is substantially the same as the direction of the central axis of the alignment treatment, and the darkest optical axis when sandwiched between crossed Nicol polarizers is one. The liquid crystal device according to any one of claims 1 to 4, wherein the liquid crystal device has an alignment state having only one. 6. The magnitude of the pretilt angle α is α ≧ 5.
The liquid crystal device according to claim 3, wherein the angle is °. 7. The liquid crystal element according to claim 3, wherein the tilt angle δ of the layer has a displacement point that increases with a decrease in temperature and then decreases. 8. The liquid crystal device according to claim 7, wherein the displacement point of δ is at a temperature of 10 ° C. or higher. 9. The liquid crystal device according to claim 7, wherein the displacement point of δ is at a temperature of 25 ° C. or higher. 10. A liquid crystal display device comprising the liquid crystal element according to claim 1, a drive circuit for the element, and a light source.