JP3083020B2 - Manufacturing method of liquid crystal element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal element used for a liquid crystal display element or a liquid crystal optical shutter, and more particularly to a method of manufacturing a ferroelectric liquid crystal element. The present invention relates to a method for manufacturing a liquid crystal element, which has improved display characteristics due to injection unevenness.

[0002]

2. Description of the Related Art Conventionally, a TN mode or the like has been adopted as a liquid crystal element and is used for many display elements. As a method for efficiently controlling the alignment in the TN mode, a substrate interface in contact with the nematic liquid crystal is formed by SiO or S by oblique deposition.
There is known a method of forming the substrate using iO ₂ or a rubbed organic resin, for example, polyimide or polyamide.

Since the TN method has no high-speed response and no memory effect, when designing a display panel with high-density pixels using the TN method, for example, a thin film transistor (TFT)
Are required in an array. However, in such an active matrix display panel using a TN liquid crystal, the TFT used is
Has a complicated structure, so that the manufacturing process is complicated and high manufacturing cost is a problem. In addition, a thin film semiconductor (for example, polysilicon or amorphous silicon) constituting a TFT is formed over a wide area. There is a problem that it is difficult to do.

As a solution to these problems, a ferroelectric liquid crystal device has been proposed (NA Clark).
And S. T. Lagerwall JP-A-56-1072
No. 16, US Pat. No. 4,367,924).

A ferroelectric liquid crystal has a first optically stable state and a second optically stable state with respect to an electric field. Therefore, unlike the liquid crystal element used for the TN type liquid crystal described above,
For example, for one electric field vector, the liquid crystal is oriented in the first optically stable state, and for the other electric field vector,
The liquid crystal is aligned in the second optically stable state. In addition, the ferroelectric liquid crystal has a property of rapidly taking one of the above two stable states in response to an applied electric field and maintaining the state when no electric field is applied. By utilizing such a property, the above-described conventional T
For many of the problems of N-type liquid crystal devices, a substantial improvement is obtained.

However, in order for the ferroelectric liquid crystal to exhibit predetermined characteristics, in the liquid crystal layer formed between the opposing substrates, liquid crystal molecules are effectively doubled in response to an externally applied electric field. It is necessary to have an orientation structure that exhibits a state transition between stable states.

A ferroelectric liquid crystal exhibits its behavior in a chiral smectic phase. The liquid crystal molecular layer having the chiral smectic phase is almost perpendicular to the substrate surface (bookshelf structure), and therefore, the liquid crystal molecular axis is in the substrate surface. It is necessary to form a region (mono-domain) that is arranged substantially parallel to or inclined with respect to.

However, smectic phase liquid crystals generally have poor alignment controllability and alignment stability as compared with nematic phase liquid crystals. In particular, sufficient characteristics cannot be obtained when the area is increased. is there.

In general, there is known a method using an orientation control film which has been subjected to a uniaxial orientation treatment such as a rubbing treatment or an oblique deposition treatment. However, it is difficult to obtain a monodomain orientation state in a large area. prone to inclination of reduction or SmC ^* phase of the layer of the tilt angle in the possible SmC ^* phase to cause the uniaxial orientation treatment on.

As means for solving these problems, Yoshinaga and Shinjo et al. Proposed that a ferroelectric liquid crystal be injected into a liquid crystal element in a chiral nematic phase (cholesteric phase) to align the liquid crystal. (JP-A-62-295021).

[0011] When a ferroelectric liquid crystal was injected into a liquid crystal element based on these proposals, a liquid crystal element exhibiting a monodomain orientation in which a chiral smectic C phase having a non-helical structure with no defect was formed. Was obtained, but in some cases, a slightly different region of contrast (hereinafter referred to as injection unevenness) slightly fanning out from the vicinity of the injection port. The present inventors speculate that this is because the molecular axis of the liquid crystal is slightly shifted for some reason. However, the uniaxiality of the liquid crystal in the region of uneven injection was uniform, and within that region, the alignment was such that it could be expressed as monodomain alignment.

At the same time, when trying to inject liquid crystal into several liquid crystal cells, the same non-uniform injection may occur in several panels.

Further, even when the injection temperature is a chiral nematic phase or a cholesteric phase, the set temperature is changed during the injection or the pressurization condition is changed for the injection. Significant injection unevenness occurred.

In addition, when examining the liquid crystal material, the same phenomenon of non-uniformity of injection occurs when an attempt is made to inject several kinds of liquid crystal materials under a specific set injection condition.

The cause of such uneven injection is that the physical properties of the liquid crystal in the chiral nematic phase (cholesteric phase) are delicate due to temperature unevenness in the injection device, temperature rise in the injection device due to pressurizing operation during injection, and the like. And a change in the injection speed and other liquid crystal injection states (hereinafter referred to as injection history).

Such a phenomenon is not so remarkable in the case of injection in a liquid crystal element having a small area, and becomes a serious problem in the case of injection in a liquid crystal element having a large area.

Such a phenomenon causes a decrease in the non-defective product rate (yield) of the liquid crystal element.

[0018]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problem, that is, to inject a ferroelectric liquid crystal into a liquid crystal element in a chiral nematic phase or a cholesteric phase. Another object of the present invention is to provide a method for manufacturing a large-area liquid crystal element that does not cause uneven injection based on the injection history.

Another object of the present invention is to provide a method for manufacturing a large-area liquid crystal element, which remarkably improves a non-defective product rate (yield) due to the appearance of uneven injection or a decrease in image quality due to minute uneven injection. Is what you do.

Another object of the present invention is to provide a method for easily setting optimum injection conditions when examining a liquid crystal material.

[0021]

Means for Solving the Problems] The present invention is opposed to
A chiral smectic in a cell with two substrates
The liquid crystal material is converted into a chiral nematic phase or
Liquid having a liquid crystal injection step of injecting in a steric phase
A method for producing a crystal element, comprising: a chiral nematic phase or
Is the helical pitch and dynamics in the cholesteric phase
Viscosity of 13 μm or more and 11 mm ² / s or more, respectively
A liquid crystal device manufacturing method, wherein the liquid crystal injecting step is performed at a temperature below .

Preferably, the liquid crystal element is housed in a vacuum vessel, and after vacuum degassing, the injection port is covered with the degassed liquid crystal, and the liquid crystal is injected into the effective display area of the liquid crystal element by applying pressure. More preferably, the pressure difference caused by pressurization is 10 kPa or more and 2000 kPa or less, more preferably 50 kPa (0.5 kg / cm
2) A method for producing a liquid crystal element, which is at least 500 kPa (5 kg / cm 2) or less, and still more preferably, in the above-mentioned production method, a temperature range of a chiral nematic phase (cholesteric phase) of the liquid crystal is: 6 ℃
This is achieved by using a liquid crystal element manufacturing method characterized by using the liquid crystal having the above.

The temperature of the ferroelectric liquid crystal described in the present invention is measured by the following method.

Method of measuring temperature A temperature monitor installed at the position shown in FIG.
The set temperature and actual temperature of the injection device, and the temperature at the time of pressurization are measured in advance, and the process is set as a condition in the program. This was performed while sequentially outputting the temperature at the position. The difference between the values of the output temperature of each temperature monitor depending on the position was about ± 0.1 ° C.

Hereinafter, the present invention will be described in detail.

FIG. 1 is a schematic sectional view showing an example of a liquid crystal element for explaining the structure of a ferroelectric liquid crystal element.

In FIG. 1, reference numeral 15 denotes a liquid crystal layer;
a and 11b are glass substrates, 12a and 12b are transparent electrodes,
13a, 13b, 14a, 14b are insulating orientation control layers,
Reference numeral 16 denotes a spacer, and 17a and 17b denote polarizing plates.

The two glass substrates 11a and 11b are respectively provided with In ₂ O ₃ , SnO ₂ or ITO (Indi).
Transparent electrodes 12a and 12b formed of a thin film such as um Tin Oxide are formed. On top of this, insulating alignment control layers 13a, 13b, 14a, 14b for wrapping a liquid crystal in a rubbing direction by wrapping a thin film of a polymer such as polyimide with a gauze or an acetate flocking cloth are formed. Insulating film materials include silicon oxides such as SiO ₂ , titanium oxides such as TiO ₂ , tantalum oxides such as Ta ₂ O ₅ , and silicon carbide, boron nitride and hydrogen containing hydrogen. Inorganic substances such as boron nitride, cerium oxide, aluminum oxide, zirconium oxide, and magnesium fluoride can be used. And an insulating layer 1 made of the above-mentioned inorganic substance.
On 3a, 13b, polyvinyl alcohol, polyimide, polyamide imide, polyester imide, polyparaxylene, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, The orientation control layers 14a and 14b made of an acrylic resin or a photoresist resin are formed to obtain an insulating orientation control layer composed of two layers of an organic material and an inorganic material. However, the insulating orientation control layer may have a single-layer structure of any of the above-described organic films and inorganic films.

[0029]

[Outside 1]

If the insulating orientation control layer is inorganic, it can be formed by vapor deposition or the like. If organic, it can be formed by dissolving an organic insulating material or its precursor solution (0.1 to 2 in a solvent).
0 wt%, preferably 0.2-20 wt%)
It can be applied by a spinner coating method, a dip coating method, a screen printing method, a spray coating method, a roll coating method, or the like, and can be cured under predetermined curing conditions (for example, under heating).

Insulating orientation control layers 13a, 13b, 14
The layer thicknesses of a and 14b are each usually 3 to 1000 nm, preferably 3 to 300 nm, and more preferably 5 to 100 n.
m is suitable.

The two glass substrates 11a and 11b are kept at an arbitrary interval by a spacer 16. For example, there is a method in which silica beads and alumina beads having a predetermined diameter are sandwiched between two glass substrates as spacers, and the periphery is bonded using a sealant, for example, an epoxy-based adhesive. Alternatively, a polymer film or glass fiber may be used as the spacer. A ferroelectric liquid crystal is sealed between the two glass substrates.

The thickness of the liquid crystal layer 15 in which the ferroelectric liquid crystal is sealed is generally 0.5 to 20 μm, preferably 1 to 20 μm.
5 μm.

In order to obtain good orientation and obtain a monodomain state in the case of a device, the ferroelectric liquid crystal must have an isotropic phase to a chiral nematic phase (cholesteric phase), a smectic A phase, a chiral smectic phase. It is desirable to have a phase transition series called C phase. A polarizing plate 17 is provided outside the glass substrates 11a and 11b.
a and 17b are stuck together. Figure 1 is a transmission type,
It has a light source.

FIG. 2 schematically shows an example of a cell for explaining the operation of the ferroelectric liquid crystal element. 21a and 2
1b is In ₂ O ₃ , SnO ₂ or IT
A glass substrate covered with a transparent electrode made of a thin film such as O (Indimu Tin Oxide), in which a liquid crystal molecule layer 22 is oriented so as to be perpendicular to the substrate surface.
Liquid crystal of C ^* phase or SmH phase is sealed. A bold line 23 represents a liquid crystal molecule, and the liquid crystal molecule 23 has a dipole moment (P⊥) 24 in a direction perpendicular to the molecule.

When a voltage exceeding a certain threshold value is applied between the electrodes on the substrates 21a and 21b, the helical structure of the liquid crystal molecules 23 is released, and the dipole moment (P⊥) 24 is directed in the direction of the electric field. 23 can change the orientation direction. The liquid crystal molecules 23 have an elongated shape and exhibit refractive index anisotropy in the major axis direction and the minor axis direction. Therefore, for example, if crossed Nicol polarizers are placed above and below the glass surface, depending on the polarity of the applied voltage, It can be easily understood that the liquid crystal optical modulator has a changed optical characteristic.

In the liquid crystal device of the present invention, the thickness of the liquid crystal layer of the liquid crystal device preferably used is sufficiently small (for example, 1
0 μm or less). As shown in FIG. 3, as the liquid crystal layer becomes thinner, the helical structure of the liquid crystal molecules is released even when no electric field is applied, and the dipole moment Pa or Pb thereof is either upward (34a) or downward (34b). Take that state. As shown in FIG. 3, when an electric field Ea or Eb having a different polarity or more than a certain threshold value is applied to such a cell by the voltage applying means 31a and 31b, the dipole moment becomes equal to the electric field Ea or Eb.
34a or downward 3 corresponding to the electric field vector of
The orientation is changed to 4b, and the liquid crystal molecules are accordingly oriented in either the first stable state 33a or the second stable state 33b.

A liquid crystal display device using the liquid crystal element according to the present invention in a display panel section and employing a data synchronization format using image data and a SYNC signal having scanning line address information shown in FIGS. 6 and 7. To achieve.

The generation of image information is performed by the graphics controller 102 on the main unit side, and is shown in FIGS.
Are transferred to the display panel 103 according to the signal transfer means shown in FIG. The graphics controller 102 is a CPU
(Central Processing Unit, hereinafter abbreviated as GCPV 112) and VRAM (Image Information Storage Memory) 114 as a core, which manages image information management and communication between the host CPU 113 and the liquid crystal display device 101. The control method of the liquid crystal display device using the elements is mainly realized on the graphics controller 102.

As the ferroelectric liquid crystal that can be used in the present invention, a liquid crystal having a chiral nematic phase and a (cholesteric phase) is desirable. As such ferroelectric liquid crystals, there are the following ones, which can be used alone or in combination of two or more. In addition, a chiral nematic phase, Alternatively, a liquid crystal composition having a chiral nematic phase or a nematic phase can be prepared by combining two or more kinds of liquid crystal compounds having no nematic phase.

Preferred liquid crystal compounds in the present invention include liquid crystal compounds having the following structures. These compounds are used as main components to prepare a ferroelectric liquid crystal composition. The compounding ratios of the respective liquid crystal compounds can be made different at appropriate times.

[0042]

[Outside 2] n and m are 0, 1, and 2 and 0 <n + m ≦ 2 R ₁ and R ₂ are a hydrogen atom, a halogen, a CN group, or
A linear or branched or cyclic alkyl group having 1 to 18 carbon atoms, wherein one or two or more methylene groups in the alkyl group are -0- , -S-, -CO-, -CHW-, -CH =
CH -, - C≡C- may be replaced by, W is a halogen, CN, a CF _3. R ₁ ,
R ₂ may be optically active.

[0043]

[Outside 3] A ₁ is,

[0044]

[Outside 4] Is represented.

X ₁ represents hydrogen or fluorine; R ₃ ,
R ₄ is a hydrogen atom, a halogen, a CN group, or a linear, branched, or cyclic alkyl group having 1 to 18 carbon atoms, and one or two or more methylene groups in the alkyl group Is -O under the condition that no heteroatoms are adjacent.
-, -S-, -CO-, -CHW-, -CH = CH-,
May be replaced by -C = C-, W is a halogen, CN, a CF _3. Further, R ₃ and R ₄ may be optically active.

[0046]

[Outside 5] B ₁ is,

[0047]

[Outside 6] Is represented.

R ₅ and R ₆ are a hydrogen atom, halogen, CN
A linear or branched or cyclic alkyl group having 1 to 18 carbon atoms, wherein 1
One or two or more methylene groups may be -O-, -S-, -CO-, -CHW
—, —CH ＝ CH—, and —C≡C— may be replaced, and W represents halogen, CN, or CF ₃ . R ₅ and R ₆ may be optically active.

[0049]

[Outside 7] C ₁

[0050]

[Outside 8] Is represented. Z is -O-, -S-

[0051]

[Outside 9] R ₇ and R ₈ are a hydrogen atom, a halogen, a CN group, or a linear, branched, or cyclic alkyl group having 1 to 18 carbon atoms, and one or two of the alkyl groups
One or more methylene groups may be -O-, -S-, -CO-, -CHW-, -CH = CH
-, -C≡C-;
Represents halogen, CN, CF ₃ . R ₇ and R ₈ may be optically active.

Preferred examples of the compounds I to IV are shown below.

More preferred examples of the compound of I

[0054]

[Outside 10] Examples of more preferred compounds of compound II

[0055]

[Outside 11] More preferred compound examples of the compound of III

[0056]

[Outside 12] Examples of more preferable compounds of compound IV

[0057]

[Outside 13]

R is a hydrogen atom, a halogen, a CN group, or a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms, and one of the alkyl groups
Alternatively, two or more methylene groups may be -O-, -S-, -CO-, -CHW-,-
CH = CH -, - C≡C- may be replaced by, W is a halogen, CN, a CF _3. Also, R
May be optically active.

X ₁ is the same as described above.

The pressurization at the time of injecting the liquid crystal is described in Japanese Patent Application Laid-Open No. Sho 62-295021, and although there is no particular limitation, a preferable pressure difference is suggested.

In the present invention, if a large-area liquid crystal display device of a type in which a liquid crystal material is injected from an injection port is to be manufactured, it is more necessary and important that a person skilled in the art knows. It should be easily understood.

Also in the present invention, the pressure difference for injection is preferably from 10 kPa to 2000 kPa, more preferably from 50 kPa to 500 kPa.

When the temperature range of the chiral nematic phase (cholesteric phase) is less than 6 ° C., the optimum injection temperature range where no injection unevenness occurs is narrowed, and a large load is imposed on the temperature control ability of the injection device. Should be understood.

If the temperature is carefully controlled, the temperature generally becomes close to the smectic A phase transition temperature, the kinematic viscosity becomes extremely large, and even if injection unevenness does not occur, an extremely long injection time is required. It should be easily understood that it will require time.

These are contrary to the intention of the present inventors to provide a manufacturing method suitable for a large-area liquid crystal element.

Therefore, it is desirable to use a liquid crystal having a chiral nematic phase (cholesteric phase) having a temperature range of 6 ° C. or more.

According to the present invention, the kinematic viscosity of the liquid crystal used for the device and the value of the cholesteric pitch (that is, the temperature condition) are adjusted to the optimum values for the liquid crystal injection process in order to produce a good liquid crystal display device exhibiting uniform contrast. The limitations are significant.

Cholesteric pitch can be made to appear by adding an optically active liquid crystal compound to a liquid crystal composition composed of a non-optically active liquid crystal compound. Performing by changing the content of the compound, or paying attention to the direction of winding the helix, an optically active liquid crystal compound of a right-handed helix,
A cholesteric pitch of several μm to several tens μm or more can be adjusted by using a left-handed helical optically active liquid crystal compound and the respective contents.

Although the kinematic viscosity varies depending on the skeleton of the liquid crystal compound used in the liquid crystal composition, the position of the functional group, and the length of the side chain, the kinematic viscosity largely depends on the temperature. Easy.

The temperature range of the cholesteric has a chiral nematic phase or a nematic phase to be contained in the composition, or has a potential to have these liquid crystal phases and appear when the composition is formed. It can be adjusted by changing the content of the liquid crystal compound.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[0072]

【Example】

Example 1 A liquid crystal composition A was prepared by mixing the above-mentioned non-optically active compound group of preferred liquid crystal compounds and an optically active compound in the following wt%.

[0073]

[Outside 14]

The phase transition temperature of the liquid crystal composition A was as follows.

[0075]

[Outside 15]

The composition A has a Ch width of 6.4 ° C., and the kinematic viscosity of the composition A changes with temperature as shown in FIG. 9, and the kinematic viscosity of 11 mm 2 / s or more is 90.6 ° C.
° C or lower.

The temperature change of the Ch pitch was as shown in FIG. 8, and the Ch pitch at 92 ° C. could not be measured. That is, when the Ch pitch is 13 μm or more, 9
It is less than 2.0 ° C. and surely 13 μm below 91.4 ° C.
That was all.

Therefore, the optimum injection temperature range that does not cause uneven injection due to the injection history described in the present invention is 85.
4 to 90.6.

The kinematic viscosity of the liquid crystal composition was measured, and
The helical pitch of the chiral nematic (cholesteric) phase can be measured as follows.

Method of Measuring Kinematic Viscosity Using a Canon-Fensque (SO) type glass viscometer (approximate constants 0.015, 0.035 (cSt / Sec)), a specified amount of liquid is supplied to a capillary tube under specified conditions. Assuming the flowing time, the measured value was obtained by multiplying the outflow time by a viscometer constant (a value unique to the viscometer) (JISZ8
803 viscosity measurement method).

The liquid crystal composition was used after degassing in an isotropic phase.

Chiral nematic (cholesteric)
Measurement method of phase helical pitch The cholesteric helical pitch was determined by the method of Matsumura et al. (Applied Physics 43, 125 (197)
4)).

Next, two 1.1 mm thick glass plates were prepared, an ITO film was formed on each glass plate, a voltage application electrode was formed, and a tantalum oxide thin film was further formed thereon by sputtering. Vapor deposition was performed to form an insulating layer.

Further, a polyimide resin precursor solution (Hitachi Chemical Co., Ltd. LQ-18) was placed on a glass plate having a tantalum oxide film.
02) A 1.0% NMP solution was applied for 15 seconds with a spinner having a rotation speed of 3000 rpm. After film formation, 27 minutes for 60 minutes
A heat condensation firing treatment was performed at 0 ° C. At this time, the thickness of the coating film was 20 nm.

The baked film was subjected to a rubbing treatment with an acetate flocking cloth, then washed with an isopropyl alcohol solution, and dispersed with silica beads having an average particle size of 1.5 μm on one glass plate. The rubbing treatment axes are made parallel to each other, and a glass plate is stuck using a sealant printing plate having a side of 10 cm square and an adhesive sealant (Structbond, Mitsui Toatsu Co., Ltd.) at 150 ° C. for 60 minutes. After heating and drying, the glass was cut around the sealant to prepare a 10 cm square experimental cell. When this cell thickness was measured in the central region and the peripheral region, about 1.
It was 5 μm.

The cell was vacuum degassed using an injection device in which the relationship between the set temperature and the cell surface temperature was confirmed in advance, while keeping the cell surface temperature at 86 to 87 ° C.

Thereafter, the liquid crystal similarly degassed under vacuum was attached to the inlet of the cell, and the cell inlet was covered with the liquid crystal.

At this time, the cell and the liquid crystal may be heated and degassed in the same injection device, or the vacuum degassed cell and the vacuum degassed liquid crystal may be placed in different injection devices, and the liquid crystal may be sequentially discharged. May be a step of covering the cell inlet.

After coating, the pressure was returned to the atmospheric pressure from the reduced pressure using dry nitrogen gas, and the pressure was further increased to about 100 kPa above the atmospheric pressure.

When returning from the reduced pressure state to the atmospheric pressure, the pressure may be returned to the normal atmosphere, but preferably returned to the dry atmosphere, and more preferably returned to an inert gas such as dry nitrogen gas. It is desirable.

It should be easily understood that this is a desirable treatment from the viewpoint of the influence of moisture on the device and the protection of organic compounds placed in an overheated state.

At this time, the cell surface temperature was reset to the set temperature of the injection device, which was previously confirmed not to exceed 90.6 ° C.

This state was maintained for 3 hours. The cell surface temperature during this holding was 89.5 to 90.3 ° C.

Thereafter, the pressure is returned to the atmospheric pressure, and
The ferroelectric liquid crystal device was prepared by gradually cooling the mixture at 0 ° C./h to 25 ° C. When the injection state was observed, there was almost no uninjected portion of the liquid crystal due to the region surrounded by the sealant.

Further, when the alignment was observed, the alignment was uniform, and the injection was performed according to the injection history such as a change in the cell surface temperature (set temperature of the injection device) and a change in the pressure in the injection device from the reduced pressure state to the pressurized state. No spots were seen.

Further, when this device was driven as a display device, a uniform driving contrast was exhibited over the entire surface, and good driving display was exhibited.

Comparative Example 1 In Example 1, the cell surface was 9
The set temperature of the injection device was set so as not to exceed 0.6 ° C. so that the cell surface would be 90.8 to 91.8 ° C. A liquid crystal device was prepared in the same manner as in Example 1 except that this state was maintained for 3 hours, and the same evaluation as in Example 1 was performed.

In the temperature range of 90.8 to 91.8 ° C., the liquid crystal material A has a Ch pitch of 14.4 to 13.4 μm,
It has a kinematic viscosity of 10.9 to 10.4 mm2 / s and is in a chiral nematic state, but does not satisfy one of the injection conditions described in the present invention (kinematic viscosity of 11 mm2 / s or more).

As a result, from the vicinity of the center of the liquid crystal element to the back side in the injection direction, a region showing an alignment state different from the periphery, which can be expressed as fan-shaped or narrow band-shaped, was observed.

Further, when driven, the above-mentioned region showed a contrast different from the surroundings. Obviously, a phenomenon called injection unevenness due to the injection history, which is referred to in the present invention, has appeared.

However, in terms of the orientation in this region, which can be called non-uniform implantation, the orientation is uniform, and since it is a monodomain, the uniaxiality between this region and the surroundings changes depending on the injection history. It is inferred that this has occurred.

Comparative Example 2 In Example 1, the cell surface was 9
The set temperature of the injector set so as not to exceed 0.6 ° C. was set to 95 ° C., which is a temperature not lower than the transition temperature from the chiral nematic phase to the isotropic phase.

A liquid crystal device was prepared in the same manner as in Example 1 except that this state was maintained for 3 hours, and evaluation was performed in the same manner as in Example 1.

As a result, in the same manner as in Comparative Example 1, from the vicinity of the center of the liquid crystal element to the back side in the injection direction, a region showing an alignment state different from that of the surroundings, which can be expressed as a fan-shaped or narrow band-shaped region, was obtained. Seen in a large area.

Further, when driven, the above-mentioned region showed a contrast different from the surroundings. Obviously, a phenomenon called injection unevenness due to the injection history, which is referred to in the present invention, has appeared.

Comparative Example 3 In Example 1, when the state was changed to the pressurized state, the cell surface was 90.
The set temperature of the injection device set so as not to exceed 6 ° C. was set so that the cell surface was 80 ° C. for 2 hours from the start of the pressurized state.

After maintaining this state for 2 hours, the cell surface was reset to a set temperature not exceeding 90.6 ° C., and this state was maintained for 1 hour, and the total pressurized state maintenance time was set to 3 hours. Prepared a liquid crystal element in the same manner as in Example 1, and performed the same evaluation as in Example 1.

As a result, from the vicinity of the injection port to the center of the liquid crystal element, a region was seen which spread in a fan shape and showed an alignment state different from that of the periphery. At the innermost part, a small amount of uninjected liquid crystal was observed.

Further, when driven, the above-mentioned region showed a contrast different from the surroundings. Obviously, a phenomenon called injection unevenness due to the injection history, which is referred to in the present invention, has appeared.

Example 2 An experiment was performed in the same manner as in Example 1 except that a seal printing plate having a side of 2 cm was used instead of the seal printing plate having a side of 10 cm used in Example 1. A cell was prepared, injected under the same injection conditions as in Example 1, and the same evaluation was performed. As a result, a liquid crystal element having uniform injection and having uniform contrast was obtained as in Example 1. Was.

Comparative Example 4 A liquid crystal device was prepared in the same manner as in Comparative Example 2 except that the experimental cell used in Example 2 was used, and the same evaluation as in Example 2 was performed. A slight phenomenon of injection unevenness, which seems to be due to the injection history, was observed around the seal at the deepest part. However, as seen in Comparative Example 1, the region where the orientation state was different from the surroundings and the region where the contrast was different were clearly pointed out. I couldn't.

As is clear from Example 1 and Comparative Examples 1 and 2, the method of the present invention for injecting a liquid crystal into a liquid crystal element within a temperature range in which the injected liquid crystal exhibits a specific property value is a chiral method. Suitable for injection in nematic phase (cholesteric phase).

Also, it can be seen that even in the same chiral nematic phase injection, there is a difference in the injection property between the isotropic phase and the injection outside the temperature range showing the physical properties described in the present invention.

Further, Examples 1 and 2 and Comparative Examples 1, 2, 3,
As is clear from FIG. 4, the liquid crystal element produced by the liquid crystal element production method of the present invention has no unevenness due to the injection history, and is particularly suitable for a large area liquid crystal element production method.

Example 3 In the same manner as in Example 1, a non-optically active liquid crystal compound group of the preferred liquid crystal compounds described above and the optically active liquid crystal compound shown below were blended in the following wt%. Composition A was made.

[0116]

[Outside 16]

The phase transition temperature of the liquid crystal composition B was as follows.

[0118]

[Outside 17]

The Ch width of the composition B is 7.4 ° C., and the temperature change of the kinematic viscosity of the composition B is as shown in FIG. 9, and the kinematic viscosity of 94.0 mm / s or more is 94.0.
° C or lower.

The temperature change of the Ch pitch was as shown in FIG. 8, and the Ch pitch at 96 ° C. could not be measured. That is, when the pitch is 13 μm or more,
When the temperature is less than 5.5 ° C and 94.5 ° C or less, it is 13 μm
That was all.

Therefore, the optimum injection temperature range that does not cause uneven injection due to the injection history described in the present invention is 88.
4-94.0 ° C.

Next, in the same manner as in the first embodiment, 10
A set temperature at which a cell of cm square was prepared, and the temperature set to maintain the cell surface temperature at 86.0 to 87.0 ° C. in the injection device could be maintained at 89.0 to 90.0 ° C. And degassed in vacuum, and further changed to liquid crystal composition A, using liquid crystal composition B, and further, from atmospheric pressure to a pressurized state,
A ferroelectric liquid crystal device was prepared in the same manner as in Example 1, except that the cell surface temperature when maintaining this state was not set again so as not to exceed 94 ° C.

The cell surface temperature during pressurization was 9
1.5-93.5C.

Observation of the injection state revealed that there was no liquid crystal uninjected portion in the region surrounded by the sealant.

Further, when the alignment was observed, it was found that the alignment was uniform and the injection unevenness due to the change in the cell surface temperature (set temperature of the injection device), the change in the pressure from the reduced pressure state to the pressurized state, and the like. I couldn't.

Further, when this device was driven as a display device, it showed a uniform contrast over the entire surface and a good driving display.

Comparative Example 5 In Example 3, when the pressure was changed to the pressurized state, the cell surface temperature was 9
The temperature of the injection device, which was set so as not to exceed 4.0 ° C., is set to 94.8 to 95.8 ° C., and the chiral nematic phase, but the optimum injection temperature described in the present invention. A ferroelectric liquid crystal device was prepared in the same manner as in Example 3 except that the temperature was set to a higher temperature side than the range, and the same evaluation as in Example 3 was performed.

As a result, from the vicinity of the center of the liquid crystal element to the back side in the injection direction, a region showing an alignment state different from the periphery, which can be expressed as a fan-like or narrow band-like shape, was observed.

Further, when driven, the above-mentioned region showed a contrast different from the surroundings.

Obviously, a phenomenon called injection unevenness according to the present invention has appeared.

However, in this region, which can be called uneven injection, the orientation is uniform and the region is mono-domain. Therefore, the uniaxiality of this region and its surroundings may change depending on the injection history. Inferred.

It can be said that these phenomena are the same as the phenomena observed in Example 1 and Comparative Example 1.

Comparative Example 6 In Example 3, when the state was shifted to the pressurized state, the cell surface temperature was 9
The set temperature of the injection device, which was set so as not to exceed 4.0 ° C., was changed to 98 ° C. (from the chiral nematic phase of the liquid crystal,
A liquid crystal device was prepared in the same manner as in Example 3 except that the temperature was set to be equal to or higher than the temperature at which the liquid crystal transitions to the isotropic phase.
The same evaluation as in Example 3 was performed.

As a result, as in Comparative Example 5, a region having an alignment state different from that of the surrounding region, which can be expressed as a fan-shaped or narrow band extending from the vicinity of the center of the liquid crystal element to the back side in the injection direction, was obtained. Seen in a larger area.

Further, when driven, the above-mentioned region showed a contrast different from the surroundings. Obviously, a phenomenon called injection unevenness due to the injection history, which is referred to in the present invention, has appeared.

Comparative Example 7 In Example 3, when the state was shifted to the pressurized state, the cell surface temperature was 9
The set temperature of the injection device set so as not to exceed 4.0 ° C. is maintained at 85 ° C. for 2 hours from the start of the pressurized state.
(Temperature below the temperature at which the liquid crystal transitions from the chiral nematic phase to the smectic A phase) and then reset to a set temperature at which the cell surface does not exceed 94 ° C.
A liquid crystal element was prepared in the same manner as in Example 3 except that the time was maintained, and the same evaluation as in Example 3 was performed.

As a result, from the vicinity of the injection port to the center of the liquid crystal element, a region showing an alignment state different from the periphery, which can be described as spreading in a fan-like or narrow band-like shape, was observed. Further, at the innermost part, a part where liquid crystal was not injected was slightly observed.

Further, when driven, the above-mentioned region showed a contrast different from the surroundings.

A phenomenon called injection unevenness due to the injection history clearly appears in the present invention.

It can be said that these phenomena are the same as the phenomena observed in Example 1 and Comparative Example 3.

[Example 4] A ferroelectric liquid crystal cell was prepared in the same manner as in Example 3 except that the cell used in Example 2 was used instead of the cell used in Example 3. As a result of performing the same evaluation, a liquid crystal element showing uniform contrast without injection unevenness as in Example 3 was obtained.

Comparative Example 8 A liquid crystal device was prepared in the same manner as in Comparative Example 6 except that the cell used in Example 4 was used instead of the cell used in Comparative Example 6, and a liquid crystal device similar to that of Comparative Example 6 was produced. When the evaluation was performed, a phenomenon that seemed to be due to the injection history was slightly observed around the seal at the deepest part in the injection direction, but the alignment state was different from that of the surroundings, as seen in Comparative Example 6, and However, it was not possible to clearly point out areas having different contrasts.

As is clear from Example 3, Comparative Example 5 and Comparative Example 6, the manufacturing method according to the present invention in which the injected liquid crystal is injected into a liquid crystal cell within a temperature range showing a specific physical property value is as follows.
Suitable for injection in chiral nematic phase (cholesteric phase).

Further, it can be seen that even in the same cholesteric phase injection, there is a difference in the injection property in the vicinity of the isotropic phase except in the temperature region exhibiting the physical properties described in the present invention.

Further, Examples 3 and 4 and Comparative Example 5
As is clear from FIGS. 6, 7, and 8, the liquid crystal element manufactured by the liquid crystal element manufacturing method according to the present invention has no uneven injection due to the injection history, and is particularly suitable for a large area liquid crystal element manufacturing method. You can see that.

[Embodiments 5 and 6] Embodiments 1 and 3
A liquid crystal element was fabricated in the same manner as in Examples 1 and 3, except that LP-64 (manufactured by Toray Industries, Inc.) was used instead of LQ-1802 used when producing the cell. The liquid crystal display device was prepared and evaluated in the same manner. As a result, a liquid crystal display device having the same results as in Examples 1 and 3 could be obtained.

Comparative Examples 9, 10, 11, 12, 13, 14 Instead of the cells used in Comparative Examples 1, 2, 3, 5, 6, and 7, the cells used in Examples 5 and 6 (the alignment film was used). LP-
Comparative Examples 1, 2,
Liquid crystal elements were prepared in the same manner as in 3, 5, 6, and 7, and the same evaluation was performed. As a result, liquid crystal elements having the same results as Comparative Examples 1, 2, 3, 5, 6, and 7 were obtained. Was only.

Examples 5 and 6 and Comparative Examples 9, 10, 11,
As is clear from FIGS. 12, 13, and 14, it is understood that the unevenness of the injection due to the injection history largely depends on the physical properties of the liquid crystal material than the type of the alignment film.

[Example 7] An optically active liquid crystal having a strong spiraling power of an optically active compound by mainly using a liquid crystal compound from the same group of liquid crystal compounds as in Examples 1 and 3. By changing to a compound, a liquid crystal composition C showing a phase transition at the following temperature was prepared. The measurement results of the cholesteric pitch and the kinematic viscosity of the liquid crystal composition C are shown in FIGS.
As shown in FIG.

[0150]

[Outside 18]

The optimum injection temperature range of the liquid crystal composition which does not cause uneven injection due to the injection history described in the present invention was 81.6 to 83.0 ° C.

The injection step was carried out at a temperature of 82.0 to 83.0 ° C. within this temperature range, and the pressurization holding time was changed to 5 hours in view of the fact that the injection was performed within a range of a large value of kinematic viscosity. When a liquid crystal element was prepared in the same manner as in Example 1,
In the same manner as in Example 1, a good liquid crystal element without uneven injection was obtained.

COMPARATIVE EXAMPLE 15 In Example 7, when the state was changed to the pressurized state, the cell surface
Is set to 86.
~ 87 ° C, cholesteric pitch is 1
A liquid crystal element was prepared in the same manner as in Example 7 except that injection was performed in a temperature range of 3 μm or less and a kinematic viscosity of 11 mm 2 / s or more. From the vicinity of the center of the liquid crystal element to the back side in the injection direction, A region showing an orientation state different from the surroundings was observed, and injection unevenness occurred due to the injection history.

[Embodiment 8] An optically active liquid crystal having a weaker helix and a smaller spiraling power by mainly using a liquid crystal compound from the same liquid crystal compound group as in Examples 1 and 3. A liquid crystal composition D exhibiting the following phase transition was prepared by changing the compound to a hydrophilic compound. The measurement results of the cholesteric pitch and kinematic viscosity of the liquid crystal composition D were as shown in FIGS.

[0155]

[Outside 19]

It can be said that the optimum injection temperature range of the liquid crystal composition that does not cause uneven injection due to the injection history described in the present invention is 80.0 to less than 84.0 ° C.

A liquid crystal element was prepared in the same manner as in Example 1 except that the injection step was performed at 80.0 to 83.5 ° C. within this temperature range. Liquid crystal element was obtained.

Comparative Example 16 In Example 8, when the state was changed to the pressurized state, the cell surface became 83.
Set the set temperature of the injection device so as not to exceed 5 ° C.
Except that injection was performed in a temperature range in which the cell surface temperature was set to not less than 84.5 ° C. and not to exceed 86.1 ° C., the cholesteric pitch was not less than 13 μm, and the kinematic viscosity was not more than 11 mm 2 / s . When a liquid crystal element was prepared in the same manner as in Example 7, a region showing an alignment state different from the periphery was found from the vicinity of the center of the liquid crystal element to the back side in the injection direction, and uneven injection due to the injection history occurred.

[Example 9] Using each of the liquid crystal composition A and the liquid crystal composition B, the cell used in Example 1 was injected in the same injection apparatus under the injection conditions of Example 1. A liquid crystal device was prepared in exactly the same manner as in Example 1 except for the above, and the same evaluation was performed.

As a result, the liquid crystal device using the composition A
The result of Example 1 was completely reproduced.

On the other hand, in the liquid crystal device using the composition B, extremely minute uneven injection was found near the injection port, and some uninjected portions were found deeper than the injection port.

Since the injection conditions were suitable for the composition A, for the composition B, when the injection port was closed,
It is sealed not in the chiral nematic phase but in the smectic A phase, and at the same time setting, it shifts from the depressurized state to the pressurized state, and due to the difference in the progress speed during injection due to the difference in kinematic viscosity Is what is happening.

[Example 10] Using each of the liquid crystal composition A and the liquid crystal composition B, the cell used in Example 1 was injected in the same injection apparatus under the injection conditions of Example 3. A liquid crystal device was prepared in exactly the same manner as in Example 1 except for the above, and the same evaluation was performed.

As a result, the liquid crystal device using the composition B
The result of Example 3 was completely reproduced.

On the other hand, in the liquid crystal device using the composition A, the same phenomenon as in the comparative example 2 occurred.

[Embodiment 11] In the ninth embodiment, the setting temperature of the injection device was changed so that the cell surface temperature before the initial sealing was from 86 to 87 ° C to 89 to 90 ° C. Further, a liquid crystal device was prepared in the same manner as in Example 8 except that the holding time of the pressurized state was changed to 5 hours, and the same evaluation was performed. The liquid crystal using the composition B in Example 9 was used. The minute injection unevenness and the non-implanted portion observed in the device were completely eliminated. In addition, the liquid crystal device using the composition A reproduced the same result as that of the ninth embodiment.

As apparent from Examples 9, 10, and 11,
Even if a liquid crystal composition that can exhibit good device characteristics is used, the injection conditions and device manufacturing conditions are suitable for one composition and inappropriate for the other composition.
It can be seen that the evaluation results sometimes conflict.

However, by setting the conditions in the process as in the present invention, it is possible to prevent the appearance of conflicting examination results that may occur due to the difference in conditions, and to carry out correct material evaluation.

[0169]

As described above, according to the liquid crystal device manufacturing method of the present invention, when the injected liquid crystal material is in a chiral nematic phase (cholesteric phase) in a temperature range where a specific physical property value is exhibited, If a liquid crystal material is injected into a liquid crystal element, injection unevenness based on the injection history does not appear.
A large-area liquid crystal element can be provided.

It can also be seen that the decrease in the yield (yield) due to the occurrence of uneven injection can be remarkably improved.

Further, it is possible to provide a method for setting the optimum device injection condition for properly evaluating the liquid crystal material.

[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 a perspective view schematically showing an example of an element cell for explaining the operation of a liquid crystal element utilizing the ferroelectricity of liquid crystal.

FIG. 3 is a perspective view schematically showing an example of an element cell for explaining the operation of a liquid crystal element utilizing the ferroelectricity of liquid crystal.

FIG. 4 is a timing chart showing a driving waveform applied to the liquid crystal element of FIG. 1;

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 graphic controller used in the present invention.

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

FIG. 8 shows a temperature change of cholesteric pitch of liquid crystal compositions A and B.

FIG. 9 is a graph showing a change in kinematic viscosity of liquid crystal compositions A and B with temperature.

FIG. 10 shows the temperature change of the cholesteric pitch of the liquid crystal compositions C and D.

FIG. 11 shows a temperature change of kinematic viscosities of liquid crystal compositions C and D.

FIG. 12 is a diagram showing a temperature monitor installation position on a liquid crystal cell.

[Explanation of symbols]

11a, 11b Glass substrate 12a, 12b Transparent electrode 13a, 13b Insulating alignment control layer (insulating film) 14a, 14b Insulating alignment control layer (alignment controlling film) 15 Liquid crystal layer 16 Spacer 17a, 17b Polarizing plate 21a, 21b Substrate 23 Liquid crystal molecules 24 Dipole moment (P⊥) 31a, 31b Voltage applying means 33a, 33b First stable state of liquid crystal molecules, or
Second stable state 34a, 34b Dipole moment indicating upward or downward 51 Liquid crystal panel 52 Scanning electrode group 53 Information electrode group 101 Liquid crystal display device 102 Graphic controller 103 Display panel 104 Scanning line driving circuit 105 Information line driving 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 front page (72) Inventor Junko Sato 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-62-34129 (JP, A) JP-A-62-54228 ( JP, A) JP-A-4-319915 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1341

Claims (6)

(57) [Claims] 1. A cell having two opposing substrates,
A method of manufacturing a liquid crystal element having a liquid crystal injection step of injecting a substance to be a chiral smectic liquid crystal in a chiral nematic phase or a cholesteric phase, wherein a helical pitch and a kinematic viscosity in a chiral nematic phase or a cholesteric phase, respectively, 13 μm or more,
And performing the liquid crystal injection step at a temperature of 11 mm ² / s or more. 2. A material that becomes a chiral smectic liquid crystal in a display area of a cell having two opposing substrates .
Chiral nematic phase quality, or a method of manufacturing a liquid crystal device having a liquid crystal injection step of injecting a state of a cholesteric phase, the chiral nematic phase, or helical pitch and a kinematic viscosity in the state of the cholesteric phase,
A method for manufacturing a liquid crystal element, wherein the liquid crystal injection step is performed at a temperature of 13 μm or more and 11 mm ² / s or more, respectively. Wherein said cell is housed in a vacuum vessel, after vacuum degassing, by pressurizing after coating the inlet with a substance to be degassed the liquid crystal, the substance serving as the liquid crystal is within the cell or 3. The method according to claim 1, further comprising a step of implanting the cell into an effective display area of the cell.
2. The method for producing a liquid crystal element according to claim 1 . 4. The pressure difference caused by pressurization is 10 kPa or less.
4. The pressure is not more than 2000 kPa.
Method of manufacturing a liquid crystal device according to. 5. The pressure difference caused by pressurization is 50 kPa or less.
The method according to claim 3, wherein the upper limit is 500 kPa or less . 6. A chiral nematic phase of the liquid crystal,
Is a liquid crystal having a cholesteric phase temperature range of 6 ° C or more.
The method for producing a liquid crystal device according to any one of claims 1 to 5, wherein the method is used.