JPH1082990A - Liquid crystal device and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obviate the occurrence of orientation defects by the flow of liquid crystal molecules and to display high-contrast images by specifying the crossing angle of the normal direction of a layer of a smectic phase and the flow direction of liquid crystal at the time of injecting the liquid crystal to be a specified angle or below. SOLUTION: A lower substrate 11 and an upper substrate 12 are adhered via a sealing material 20 to constitute a liquid crystal cell 25. The sealing material 20 is formed into a frame shape in the outer peripheral edges of the lower substrate 11 and the upper substrate 12. The sealing material 20 is formed with an opening (liquid crystal injection port) 20A for liquid crystal injection and the opening 20A is sealed by a sealing material 20B. The normal direction 21H of the layer (smectic layer) of the laminar structure of the smectic phase constituting the liquid crystals 21 is so set as to cross at <=1.5 deg. the direction perpendicular to the end face of the liquid crystal injection port 20A (the direction perpendicular to the side of the sealing material 20 where the liquid crystal injection port 20A is formed) in order to prevent the disturbance in the orientation of the liquid crystals 21. The normal direction 21H of the smectic layer is so determined as to have the intersection angle Φ in the direction 21C of the orientation treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal device using a smectic phase liquid crystal and a method of manufacturing the same.

[0002]

2. Description of the Related Art Instead of a liquid crystal display device using a nematic liquid crystal, which has been widely used, a ferroelectric liquid crystal and an antiferroelectric liquid crystal, which are expected to have a high-speed response characteristic and a wide viewing angle characteristic, are used. Liquid crystal display devices have been developed. In these liquid crystal display elements, a ferroelectric liquid crystal or an antiferroelectric liquid crystal is interposed between a pair of substrates having electrodes formed on opposing surfaces.

In the case of using a ferroelectric liquid crystal, a first alignment stable state in which liquid crystal molecules are aligned in one ferroelectric phase by applying a predetermined voltage of one polarity between opposing electrodes, By applying a predetermined voltage of the other polarity between the electrodes and driving the liquid crystal molecules using the bistability with the second alignment stable state in which the liquid crystal molecules are aligned in the other ferroelectric phase, a desired image is formed. Is displayed.

[0004] In the case of using an antiferroelectric liquid crystal,
A first alignment stable state in which liquid crystal molecules are aligned in one ferroelectric phase by applying a predetermined voltage of one polarity between opposing electrodes, and a predetermined voltage of the other polarity is applied between the electrodes. This makes use of the three stability of the second alignment stable state in which the liquid crystal molecules are aligned in the other ferroelectric phase and the third alignment stable state in which the liquid crystal molecules are aligned in the antiferroelectric phase when no electric field is applied. And a desired image is displayed by driving.

In these liquid crystal display devices, liquid crystal molecules are aligned in a stable state of a ferroelectric phase or an antiferroelectric phase,
The binary display is performed using the memory effect.
It is difficult to perform gradation display with good reproducibility.

A DHF liquid crystal (Deformed Helical Ferroelectric L
Liquid crystal display devices using iquid crystal) have been proposed. A DHF liquid crystal display element has a liquid crystal from one ferroelectric phase to another ferroelectric phase by interposing a ferroelectric liquid crystal between substrates in the presence of a helix drawn by molecules and distorting the helix according to an electric field. It changes the director of the molecule continuously.

Further, recently, an antiferroelectric liquid crystal display device which performs gradation display using an intermediate alignment state of some antiferroelectric liquid crystals has been proposed.

A liquid crystal display device using a ferroelectric liquid crystal and an antiferroelectric liquid crystal has a liquid crystal cell having an inner surface subjected to an alignment treatment, a liquid crystal filled in the liquid crystal cell, and a liquid crystal cell interposed therebetween. And a pair of polarizing plates. The ferroelectric liquid crystal is composed of a smectic C ^* phase liquid crystal, and the antiferroelectric liquid crystal is composed of a smectic CA ^* phase liquid crystal. These liquid crystals are aligned in the liquid crystal cell with the normal of the layer having the layer structure having the smectic phase substantially matching the direction of the alignment treatment.

[0009]

A liquid crystal display device using a ferroelectric liquid crystal and an antiferroelectric liquid crystal is a cell formed by joining a pair of substrates which have been subjected to an alignment treatment such as rubbing in a predetermined direction. It is manufactured by injecting liquid crystal by a vacuum injection method or the like.

However, since the ferroelectric liquid crystal and the antiferroelectric liquid crystal have high viscosity, when the liquid crystal is injected, a shear stress acts between the liquid crystal molecules due to the flow of the injected liquid crystal. For this reason, the liquid crystal molecules are arranged along the flow of the liquid crystal molecules, so that uniaxial alignment cannot be obtained and alignment defects occur. In particular, since the liquid crystal in the smectic phase has a layer structure, if an alignment defect occurs partially, it also affects the alignment of the other layers, and as a result, the size of the defect domain increases and the generation of defects occurs. Density increases. Therefore, the black level is reduced, the contrast is reduced, and the display quality is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a liquid crystal device using a liquid crystal having a ferroelectric phase, which has few alignment defects, and a method for manufacturing the same.

[0012]

In order to achieve the above object, in a liquid crystal device according to a first aspect of the present invention, electrodes are formed on surfaces facing each other, and at least one of the facing surfaces is rubbed. A pair of substrates, having a liquid crystal injection port, a frame-shaped sealing material that joins the pair of substrates, and injected from the liquid crystal injection port into a region formed by the pair of substrates and the sealing material; A smectic phase liquid crystal having a layer structure of a smectic phase, wherein an intersection angle between a normal direction of the layer and a normal of an end face of the liquid crystal injection port is 1.5 ° or less, and sealing for sealing the liquid crystal injection port; And a material.

According to this configuration, the intersection angle between the normal line of the end face of the liquid crystal injection port and the normal direction of the layer of the layer structure of the smectic phase (smectic layer) is set to 1.5 ° or less. That is, the main direction of the flow of the injected liquid crystal and the normal direction of the smectic layer are set substantially parallel. For this reason, a smectic liquid crystal layer with few alignment defects caused by the flow of the liquid crystal during the injection of the liquid crystal can be obtained. Therefore,
Prevents the black level from dropping due to alignment defects.
High-contrast, high-quality images can be displayed. In general, the normal direction of the smectic layer is inclined at a predetermined angle with respect to the direction of the alignment processing performed on the inner surface of the substrate. Therefore, the direction (normal line) of the end face of the liquid crystal injection port is set in consideration of the tilt angle.

In order to achieve the above object, a second aspect of the present invention is provided.
The liquid crystal device according to the aspect of the present invention has a pair of substrates having electrodes formed on surfaces facing each other, a liquid crystal injection port, a frame-shaped sealing material for joining the pair of substrates, the pair of substrates, A liquid crystal of a smectic phase injected from the liquid crystal injection port into a region formed by the sealing material, and a long side of the liquid crystal injection region formed by the pair of substrates and the sealing material is represented by X; Is the number n of the liquid crystal injection ports, and the ratio k = Y / P of the position P and Y at which the boundary between the injected liquid crystal and the non-injected region is parallel to the short side Y is represented by Expressions 7 and 8. Is satisfied.

[Mathematical formula-see original document] n = int (k * X / (2 * Y)) int indicates a natural number

[Equation 8] 5 ≦ k ≦ 6

[0015] i-th of said liquid crystal inlet is desirably arranged at a position x _i as represented by Equation 9.

X _i = X / (2 · i + 1) i = 1,2,..., N

According to these configurations, the smectic phase liquid crystal can be injected into the liquid crystal cell at high speed from the plurality of injection ports. In addition, by arranging the number and position of the injection ports as shown in Equations 7 to 9, the flow of the liquid crystal at the time of injection can be made almost uniaxial, and alignment defects and the like due to disturbance of the flow of the liquid crystal can be prevented. it can. In addition, the number of injection ports is not too large, and there is no problem with the strength of the liquid crystal cell.

In order to achieve the above object, a third aspect of the present invention is provided.
The method for manufacturing a liquid crystal device according to the aspect of the present invention includes: a pair of substrates in which electrodes are formed on surfaces facing each other, and rubbing is performed on at least one of the opposing surfaces, and a liquid crystal injection port. Forming a liquid crystal cell composed of a frame-shaped sealing material for joining portions, and a smectic phase in which a liquid crystal of a smectic phase is inclined at a predetermined angle with respect to the rubbing direction from the liquid crystal injection port to the liquid crystal cell. Injecting liquid crystal of the smectic phase so as to have a main axis of flow in a direction in which the intersection angle with the normal direction of the layer of the layer structure is 1.5 ° or less, and sealing the liquid crystal injection port, Is provided.

According to this configuration, the intersection angle between the principal axis of the flow rate of the injected liquid crystal and the normal direction of the smectic layer is 1.5.
° is set below. That is, the main direction of the flow of the injected liquid crystal and the normal direction of the smectic layer are set substantially parallel. For this reason, a smectic liquid crystal layer with few alignment defects caused by the flow of the liquid crystal during the injection of the liquid crystal can be obtained. Therefore, a decrease in the black level due to the alignment defect is prevented, and a high-contrast, high-quality image can be displayed. The angle between the flow direction of the liquid crystal during liquid crystal injection and the normal direction of the smectic layer is determined by taking into account that the normal of the smectic phase is inclined at a predetermined angle in the direction of the alignment processing performed on the inner surface of the substrate. Is determined. Thereby, the intersection angle between the normal direction of the smectic layer and the main direction of the flow of the liquid crystal is set to 1.5 ° or less.

In order to achieve the above object, a fourth aspect of the present invention is provided.
The method for manufacturing a liquid crystal device according to the aspect of the present invention includes: a pair of substrates in which electrodes are formed on surfaces facing each other, and rubbing is performed on at least one of the opposing surfaces, and a liquid crystal injection port. A frame-shaped sealing material for joining the parts, a step of forming a liquid crystal cell composed of, and a step of injecting a smectic phase liquid crystal into the liquid crystal cell from the liquid crystal injection port; The long side of the liquid crystal injection region formed by the sealing material is X, the short side is Y, the number n of the liquid crystal injection ports, and the boundary between the injected liquid crystal and the non-injection region is parallel to the short side Y. The ratio k = Y / P between the position P and Y satisfies Expression 10 and Expression 11.

[Mathematical formula-see original document] n = int (k * X / (2 * Y))

[Equation 11] 5 ≦ k ≦ 6

[0020] i-th of said liquid crystal inlet is desirably arranged at a position x _i as represented by Equation 12.

X _i = X / (2 · i + 1) i = 1, 2,..., N

According to these configurations, the smectic phase liquid crystal can be injected into the liquid crystal cell at high speed from the plurality of injection ports. Moreover, by arranging the number and position of the injection ports as shown in Equations 10 and 12, the flow of the liquid crystal at the time of injection can be made almost uniaxial, and alignment defects and the like due to disturbance of the flow of the liquid crystal can be prevented. it can. In addition, the number of injection ports is not too large, and there is no problem with the strength of the liquid crystal cell.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a display element of this embodiment, and FIG. 2 is a plan view of a transparent substrate on which pixel electrodes and active elements are formed.

This display element is of an active matrix type. As shown in FIG. 1, a pair of transparent substrates (for example, glass substrates) 11 and 12 and a pair of transparent substrates 11 and 12 are provided.
12 and a liquid crystal 21 disposed between the transparent substrates 11 and 12.
, And a pair of polarizing plates 23 and 24 disposed therebetween.

In FIG. 1, a lower transparent substrate (hereinafter, referred to as a lower substrate) 11 has a pixel electrode 13 made of a transparent conductive material such as ITO and a thin film transistor (hereinafter, a TFT) having a source connected to the pixel electrode 13. 14 are formed in a matrix.

As shown in FIG. 2, a gate line (scanning line) 15 is arranged between rows of the pixel electrodes 13, and a data line (gradation signal line) 16 is arranged between columns of the pixel electrodes 13. The gate electrode of each TFT 14 is connected to a corresponding gate line 15, and the drain electrode is connected to a corresponding data line 16. Gate line 15
Is connected to a row driver (not shown) and the data line 16
Are connected to a column driver (not shown). The row driver and the column driver are, for example, COG (chip-on-glass)
Depending on the method, it may be arranged on the lower substrate 11.

In FIG. 1, an upper (transparent) electrode 12 is formed on an upper transparent substrate (hereinafter referred to as an upper substrate) 12 so as to oppose each pixel electrode 13 of the lower substrate 11 and to which a common voltage Vcom is applied. ing. The common electrode 17 is, for example, an IT
It is a transparent electrode formed of O or the like.

Alignment films 18 and 19 are provided on the electrode forming surfaces of the lower substrate 11 and the upper substrate 12, respectively. The alignment films 18 and 19 are horizontal alignment films made of an organic polymer compound such as polyimide, and at least one of the opposing surfaces has been subjected to an alignment process of rubbing once in a direction parallel to and opposite to each other. .

The lower substrate 11 and the upper substrate 12 are adhered to each other via a sealing material 20 to form a liquid crystal cell 25. The sealing material 20 is formed in a frame shape on the outer peripheral edge of the lower substrate 11 and the upper substrate 12, as indicated by a broken line in FIG. Seal material 2
An opening 20A for injecting liquid crystal (liquid crystal injection port) 20A is formed at 0, and this opening 20A is sealed with a sealing material 20B. The liquid crystal 21 is sealed in a region surrounded by the substrates 11 and 12 and the sealant 20. The interval between the alignment films 18 and 19 is determined by the sealing material 20 and the spacer 22, for example,
It is regulated at a constant interval of 1.4 μm to 2.4 μm.

In the bulk state, the liquid crystal 21 has a single helical structure (in the case of ferroelectric liquid crystal) or a double helical structure (in the case of antiferroelectric liquid crystal), and the gap length of the liquid crystal cell 25 is small. Since the pitch is shorter than the helical pitch, the helical pitch is sealed in the liquid crystal cell 25. In addition, the liquid crystal 21
Each molecule has a spontaneous polarization Ps, and preferably, twice (cone angle) 2θ of the angle (tilt angle) θ between the cone axis and the cone drawn by the molecule is larger than 45 ° (preferably,
It is composed of a liquid crystal composition (ferroelectric liquid crystal or antiferroelectric liquid crystal) having a chiral smectic C phase or a CA phase (SmC ^* or SmCA ^* ). The horizontal component of the director of the liquid crystal 21 (the average orientation direction of the liquid crystal molecules) (the direction projected on a plane parallel to the main surfaces of the substrates 11 and 12) changes continuously according to the applied voltage.

As the liquid crystal having such characteristics, for example, a liquid crystal substance (1) having a skeleton structure represented by Chemical Formula 1
There is an antiferroelectric liquid crystal obtained by mixing (3) at 20% by weight, 40% by weight, and 40% by weight, respectively.

[0031]

Embedded image

Next, the relationship between the direction of the alignment treatment applied to the alignment films 18 and 19, the optical axis of the polarizing plates 23 and 24, and the alignment direction of the liquid crystal molecules of the liquid crystal 21 will be described with reference to FIG.

In FIG. 3, reference numeral 21C denotes an alignment film 18,
19 shows the direction of the orientation treatment performed. The liquid crystal 21 is oriented such that the normal 21H of the layer having the layer structure of the chiral smectic C phase or CA phase intersects the orientation direction 21C at an intersection angle φ of about 0 ° to ± 10 °. The intersection angle Φ changes depending on the composition of the liquid crystal 21, the compositions of the alignment films 18 and 19, and rubbing conditions. This intersection angle Φ can be obtained in advance by experiments or the like.

In order to prevent the alignment of the liquid crystal 21 from being disturbed, the direction of the normal line of the layer (smectic layer) of the layer structure of the smectic phase constituting the liquid crystal 21 is perpendicular to the end face of the liquid crystal injection port 20A (the sealing material). The direction perpendicular to the side where the 20 liquid crystal injection ports 20A are formed is set to intersect at 1.5 ° or less. The direction of the normal line of the smectic layer is determined so as to have an intersection angle Φ in the direction 21C of the alignment treatment. Therefore, the direction of the orientation process 21C and the direction of the end face of the liquid crystal injection port 20A is such that the imaginary line intersecting the orientation process direction 21C at an angle Φ and the normal of the end face of the liquid crystal injection port 20A intersect at 1.5 ° or less. It is designed to be.

When a voltage lower than the predetermined negative voltage -VS is applied to the liquid crystal 21, the liquid crystal 21 enters a first alignment state (ferroelectric phase), and the alignment direction of the liquid crystal molecules is substantially in the first direction 21A. Becomes When a voltage higher than the predetermined positive voltage + VS is applied to the liquid crystal 21, the liquid crystal 21 enters the second alignment state, and the alignment direction of the liquid crystal molecules is substantially the second direction 21.
B. On the other hand, when the applied voltage is 0, the average alignment direction (director) of the liquid crystal molecules is almost the normal direction of the smectic phase layer of the liquid crystal 21, that is, the first and second directions 21.
Almost intermediate direction between A and 21B (almost the direction of alignment treatment) 2
1C.

The deviation angle 2θ between the first direction 21A and the second direction 21B is 45 ° or more, preferably 60 ° or more. The optical axis (transmission axis in this embodiment) 23A of the polarizing plate 23 is composed of a first direction 21A and an alignment processing direction 21A.
C, approximately 22.5 ° with respect to the alignment direction 21C.
The direction is set. Transmission axis 24A of polarizing plate 24
Is set in a direction substantially orthogonal to the transmission axis 23A of the polarizing plate 23.

As shown in FIG. 3, in the display device in which the transmission axes 23A and 24A of the polarizing plates 23 and 24 are set, the average alignment direction (director) of the liquid crystal molecules is changed by the transmission axis 2 of the polarizing plate 23.
3A, the transmittance is lowest (the display is darkest), and the average alignment direction of the liquid crystal molecules is changed to the polarization plate 2.
The transmittance becomes highest (brightest) when the direction 21D is set at 45 ° with respect to the transmission axis 23A of No.3. For this reason,
A relatively low frequency (0 .0) between the pixel electrode 13 and the common electrode 17.
The transmittance when a sawtooth voltage (approximately 1 Hz) is applied changes continuously as shown in FIG. Therefore, the voltage V when the maximum transmittance Tmax and the minimum transmittance Tmin are obtained.
By adjusting the applied voltage between Tmax and VTmin, an arbitrary gradation can be displayed.

Next, a method for manufacturing a liquid crystal display device having such a configuration will be described. First, the pixel electrode 1 is placed on the lower substrate 11.
3, TFT 14, gate line 15, data line 16
Etc., and further, a polyimide alignment film 1 is formed thereon.
8 is formed. Further, the surface of the alignment film 18 is rubbed in a predetermined direction. The rubbing direction 21C is Φ−1.5 ° to Φ + 1.5 with respect to the direction perpendicular to the end face of the liquid crystal injection port 20A formed in a later step (the direction parallel to the gate line 15).
° The direction is inclined. As described above, the tilt angle Φ changes depending on the liquid crystal material, the material of the alignment film, the strength of rubbing, and the like, and these intersection angles Φ can be obtained in advance by experiments and the like.

A common electrode 17 is formed on the upper substrate 12, and a polyimide alignment film 19 is formed on the common electrode 17.
To form Further, the surface of the alignment film 19 is rubbed in a predetermined direction. The rubbing direction is substantially the same as the rubbing direction applied to the alignment film 18.

Rubbing is performed in the direction opposite to the direction 21C.
It is desirable to perform the operation once, and then once in the direction 21C in order to stabilize the orientation.

Next, for example, an uncured sealing material 20 having a liquid crystal injection port 20A is applied on the lower substrate 11 as shown in FIG. At this time, the liquid crystal injection port 20A is set so that the normal of its end face is Φ−1.5 ° to Φ
The shape is such that the direction is inclined by + 1.5 °. Further, the spacers 22 are sprayed.

Subsequently, the two substrates 11 and 12 are joined. At this time, adjustment is performed so that the rubbing directions applied to the alignment films 18 and 19 are parallel.

Subsequently, the liquid crystal 21 is injected into the liquid crystal cell 25 by the method shown in FIGS. That is, FIG.
The device is arranged as shown in FIG. 5B, and as shown in FIG. 5A, the pressure in the vacuum chamber 51 is controlled, and the temperatures of the liquid crystal 21 and the liquid crystal cell 25 are reduced as shown in FIGS. The liquid crystal 21 is injected into the liquid crystal cell 25 by the processing shown in FIG.

First, as shown in FIG.
Is placed in a vacuum chamber 51 in which a dispenser 52 holding a liquid crystal 21 for injection and a lamp heater 53 are installed. The dispenser 52
A heater 52A for heating the held liquid crystal 21 is provided.

Next, the inside of the vacuum chamber 51 is
4 to reduce the pressure (process P1 in FIG. 5D). Further, the liquid crystal 21 inside is heated by the heater 52A of the dispenser 52. However, the temperature of the liquid crystal cell 25 is 25
Maintain at about room temperature. About 8 minutes, vacuum chamber 5
The pressure inside 1 is reduced to 1.0 × 10 ⁻² Torr, and the liquid crystal 21 in the dispenser 52 is heated to about 100 ° C. The air pressure in the vacuum chamber 51 and the temperature of the liquid crystal 21 in the dispenser 52 are maintained for about 2 minutes, and bubbles in the liquid crystal 21 are removed (defoamed) (process P2).

Subsequently, the valve 55 of the vacuum chamber 51 is opened to introduce air (or an inert gas such as nitrogen gas).
Normal pressure (approximately 1.6 × 10 ² Tar) in the vacuum chamber 51
r. Return to Further, the inside of the vacuum chamber 51 is naturally cooled, and the temperature of the liquid crystal 21 is returned to normal temperature (process P3).

Subsequently, the pressure in the vacuum chamber 51 is reduced to 1.0 × 10 ⁻² Torr at normal temperature (process P4), and this state is maintained for about 15 minutes, so that the molecular The gas molecules adhering at the level are removed (degasified) (process P5). Subsequently, the dispenser 52
The heater 52A in the inside is energized to heat the liquid crystal 21 to about 100 ° C. (process P6). Further, the lamp heater 5
3 is turned on to heat the liquid crystal cell 25 (process P
7).

When both the temperature of the liquid crystal 21 and the temperature of the liquid crystal cell 25 reach about 100 ° C., as shown in FIG.
The liquid crystal 21 is dropped on the substrate (process P8). After dropping, the heater 52A is turned off to prevent the liquid crystal 21 in the dispenser 52 from deteriorating. For this reason, the temperature of the liquid crystal 21 in the dispenser 52 gradually decreases.

Subsequently, the valve 55 is opened to introduce the atmosphere (or an inert gas) or the like into the vacuum chamber 51, and the pressure in the vacuum chamber 51 is gradually increased. Due to the difference between the pressure in the liquid crystal cell 25 (substantially vacuum) and the pressure in the vacuum chamber 51, a gradually increasing pressure is applied to the dropped liquid crystal 21, and the dropped liquid crystal 21 is injected into the liquid crystal cell 25. . During this time, the temperature of the liquid crystal cell 25 and the dropped liquid crystal 21 is maintained at about 100 ° C., and the fluidity of the liquid crystal 21 is maintained (process P9).

After completion of the injection, the lamp heater 53 is turned off to cool the injected liquid crystal 21 and liquid crystal cell 25 (process P10). Subsequently, the liquid crystal cell 25 is taken out of the vacuum chamber 51, the liquid crystal injection port 20A is sealed with a thermosetting or photocurable sealing material 21B, and this is cured. Subsequently, the polarizing plates 23 and 24 are arranged on both sides of the liquid crystal cell 25 to complete the liquid crystal display device.

According to this manufacturing method, the rubbing direction 21
C is approximately Φ with respect to the direction perpendicular to the end face of the liquid crystal injection port 20A.
It is inclined at an angle of −1.5 ° to Φ + 1.5 °. Therefore, the main direction of the flow of the injected liquid crystal 21 is as shown in FIG.
As shown in FIG. 7, the liquid crystal is substantially parallel to the normal direction of the smectic layer of the injected liquid crystal. Therefore, even if the alignment stress acts on the liquid crystal molecules due to the flow of the liquid crystal 21, the alignment regulating force by the alignment force acts on the liquid crystal molecules in the same manner as the alignment regulating force by the alignment treatment. The alignment is performed without occurrence, and the completed liquid crystal device has few alignment defects. In addition, according to this manufacturing method, the liquid crystal is dropped on the panel by the dispenser, so that the liquid crystal comes into contact with the panel only in the vicinity of the liquid crystal injection port, and waste of the liquid crystal and contamination of the liquid crystal can be prevented.

The present invention can be applied to a method for manufacturing a liquid crystal display element using a so-called dip injection method. In this method, the processes P1 to P7 are substantially the same as those described above. However, in the process P8, instead of dropping the liquid crystal, as shown in FIG. 25 liquid crystal injection ports 20A are immersed. Subsequently, the valve 55 is opened to return the inside of the vacuum chamber 51 to normal pressure, and the liquid crystal 21 is injected into the liquid crystal cell 25 by a pressure difference between the inside and outside of the liquid crystal cell 25. During this time, the liquid crystal in the liquid crystal dish 56 is heated by the heater 57 and the liquid crystal cell 25 is heated by the panel heater 58, so that the fluidity of the liquid crystal is maintained.

According to this manufacturing method, the rubbing direction 2
1C is inclined at an angle of approximately Φ-1.5 ° to Φ + 1.5 ° with respect to a direction perpendicular to the end face of the liquid crystal injection port 20A. For this reason, the main direction of the flow of the injected liquid crystal 21 is as shown in FIG.
As shown in (A), the liquid crystal is substantially parallel to the normal direction 21H of the smectic layer of the injected liquid crystal. Therefore, the liquid crystal 2
Even if the shearing stress acts on the liquid crystal molecules due to the flow of 1, the alignment regulating force by the shearing force acts on the liquid crystal molecules in the same manner as the alignment regulating force by the alignment treatment, so that the liquid crystal molecules do not cause defects. The alignment is completed, and the completed liquid crystal device has few alignment defects.

The relationship between the shift angle between the direction of the principal axis of the flow of the liquid crystal 21 and the normal direction of the smectic layer and the display contrast during liquid crystal injection was measured. FIG. 9 shows the result. As shown in FIG. 7B, in the liquid crystal display device in which the liquid crystal 21 is injected in a direction not parallel to the normal line of the smectic layer, the display contrast (Tmax / Tmin) is on the plus side of the shift angle (the shift angle is 1. It is less than 90 on the minus side (greater than 5 °) and less than 85 on the minus side (the deviation angle is less than 1.5 °). On the other hand, as shown in FIG. 7A, a direction parallel to the layer normal of the smectic layer (the deviation angle is −1.5 ° to + 1.5 °).
The display contrast of the liquid crystal display device in which the liquid crystal 21 was injected was 85 to 93, and it was confirmed that the display contrast was greatly improved.

In the above description, the liquid crystal injection port 20A is arranged on the long side of the liquid crystal cell 25. This is the liquid crystal injection port 20
This is because, when A is disposed on the short side, the inflow path after the injection is long, and alignment deterioration is likely to occur. Liquid crystal inlet 2
The display contrast when 0A is arranged on the short side is further lower than the level shown in the graph of FIG.

In the first embodiment, the liquid crystal injection port 2
When 0A is narrow, as shown in FIG. 10, the injected liquid crystal 21 spreads and flows, so that the flow direction of the liquid crystal 21 greatly deviates from the normal direction 21H of the smectic layer, and the flow becomes strong. Alignment defects occur along. In addition, since there is one liquid crystal injection port 20A, it takes time to inject the liquid crystal. If it takes time to inject the liquid crystal,
Impurities such as oil from the oil pump easily enter the liquid crystal 21. Further, in the vacuum injection method and the like, since the injection is performed by heating, there is a problem that the liquid crystal 21 and the alignment films 18 and 19 are deteriorated, and the alignment force is further reduced. Therefore, the second
As an embodiment of the present invention, a method for solving such a problem will be described.

In this embodiment, FIG.
As shown in (A) and (B), a plurality of liquid crystal injection ports 20A are provided.
Are arranged on the long side of the sealing material 20. Seal material 20
The length of the short side is Y, the length of the long side is X, the width x of each injection port is 0.1X, the number of the injection ports is n, and the number of the injection ports is n from the left end of the cell of the i-th injection port. If the position is referred to as x _i, injection talkative n and inlet position x _i is set to satisfy the equation 13 to equation 15.

[0058]

## EQU13 ## n = int (k.X / (2.Y))

[Expression 14] 5 ≦ k ≦ 6

X _i = X / (2 · i + 1) i = 1, 2,..., N

Here, k indicates the reciprocal of the ratio of the position where the boundary between the liquid crystal and the vacuum at the time of vacuum injection becomes substantially parallel to the X axis and Y. For example, if k = 5, it means that the boundary line becomes parallel at the position of Y / 5, as shown in FIG.

The time required to inject the liquid crystal 21 into the liquid crystal cell 25 depends on the time until the boundary between the injected liquid crystal and the vacuum becomes substantially parallel to the X axis. For example, FIG.
As shown in (B), the time required for the boundary line to be parallel to the X axis is long, and when k is small, the total time required for the injection is also long. In addition, as shown in FIG. 12C, the time required for the boundary line to be parallel to the X-axis is short, and as k increases, the total time required for implantation also decreases.

From the viewpoint of increasing the injection speed, k is desirably 5 or more. However, even if k is larger than 6, the boundary line becomes relatively parallel to the X axis relatively quickly.
Rather, the injection time after the boundary line becomes parallel to the X axis affects the total injection time, and the total injection time does not change even if k is changed. Further, in order to increase k, it is necessary to increase the number of injection ports n. However, if n is too large, the strength of the liquid crystal cell 25 decreases, and the cell gap (the thickness of the layer of the liquid crystal 21) becomes uneven. This causes problems such as deterioration of image quality. For this reason, k is given by Equation 1.
As shown in 4, it is desirable that the number be 5 or more and 6 or less.

For example, if X is 4L and Y is 3L, and it is desired to make the boundary between the vacuum and the injected liquid crystal parallel at the position of Y / 5, the number n of the liquid crystal injection ports 20A is given by the following equation. It becomes 3 according to 13. Then, according to Equation 15, 1
Th liquid crystal injection port position x ₁ is, X / 3 from one end of the long side
And the position x ₂ of the _second liquid crystal inlet is
From one end of the long side (X / 3) + (X / 5) = 8X / 15 position of the third position x ₃ of the liquid crystal inlet is from one end of the long side (8X / 15) + (X / 7 ) = 8X / 15.

According to such a configuration, at the time of vacuum injection,
After the boundary between the injected liquid crystal 21 and the vacuum becomes parallel to the X axis at the position of Y / 5 or Y / 6, this boundary line rises while being substantially parallel to the X axis. Accordingly, by making the normal direction of the smectic layer coincide with the Y-axis direction, it is possible to make the main axis direction of the liquid crystal injection flow substantially parallel to the normal line direction of the smectic layer, as in the first embodiment. As a result, it is possible to prevent alignment defects generated when the liquid crystal 21 is injected. Also,
Since the liquid crystal injection time can be short, contamination of impurities and deterioration of the liquid crystal can be reduced.

The present invention is not limited to the above-described embodiment, and various modifications and applications are possible. For example, in the second embodiment, the width of each liquid crystal injection port is set to 0.1X.
However, the size of the injection port is arbitrary, and may be 0.05X or 0.2X. Further, the position of each liquid crystal injection port is not limited to the above position.

The arrangement and the like of the polarizing plates 23 and 24 shown in FIG. 3 are merely examples, and can be arbitrarily changed. For example, the transmission axis 24A of the polarizing plate 24 and the transmission axis 23A of the polarizing plate 23 may be set in parallel. Further, an absorption axis may be used instead of the transmission axis. Also, the first direction 21A and the second
The optical axis of one polarizing plate is arranged in the middle direction (direction parallel to the normal direction 21H of the smectic layer) of the direction 21B, and the optical axis of the other polarizing plate is parallel to the optical axis of one polarizing plate or They may be arranged so as to be orthogonal.

The present invention is not limited to a display element using a TFT as an active element, but is also applicable to a display element using an MIM as an active element. Further, according to the present invention, as shown in FIG. 13, a scanning electrode 71 and a signal electrode 72 orthogonal to the scanning electrode 71 are provided on the opposing surfaces of the opposing substrates 11 and 12.
Matrix type with passive matrix (passive matrix type)
It is also applicable to the display element of the above. In addition, a color filter can be arranged and used as a color liquid crystal display element.

[0067]

As described above, according to the display device of the present invention, the intersection angle between the normal direction of the smectic phase layer and the flow direction of the liquid crystal at the time of injecting the liquid crystal is approximately 1.5 °.
Since the following conditions are satisfied, it is possible to obtain a liquid crystal display device that displays a high-contrast image without causing an alignment defect due to the flow of liquid crystal molecules. In addition, since the number and positions of the injection ports are appropriately arranged, liquid crystal molecules can be injected in a short time without causing alignment defects. Furthermore, since the liquid crystal is driven without using a ferroelectric phase, a display element with less display burn-in due to spontaneous polarization can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a plan view showing a configuration of a lower substrate of the liquid crystal display device shown in FIG.

FIG. 3 is a diagram showing a relationship between a transmission axis of a polarizing plate, an alignment direction of liquid crystal molecules, and a liquid crystal injection port.

FIG. 4 is a diagram showing a relationship between an applied voltage and transmittance of the liquid crystal display device shown in FIG.

FIG. 5A is a diagram showing a change in pressure in a vacuum chamber in the method for manufacturing the liquid crystal display device shown in FIG. 1;
(B) is a diagram showing a change in the temperature of the liquid crystal in the method for manufacturing the liquid crystal display device shown in FIG. 1, and (C) is a diagram showing the change in the temperature of the liquid crystal cell in the method for manufacturing the liquid crystal display device shown in FIG. FIG. 2D is a diagram showing a step in the method for manufacturing the liquid crystal display device shown in FIG. 1.

FIG. 6 is a view for explaining the method for manufacturing the liquid crystal display device shown in FIG.

7A is a diagram showing an example in which the main direction of the flow of the injected liquid crystal is parallel to the normal direction of the smectic layer of the injected liquid crystal, and FIG. It is a figure which shows the example in the case where the main direction of flow and the normal direction of the smectic layer of the injected liquid crystal are largely inclined.

FIG. 8 is a diagram for explaining a method of manufacturing the liquid crystal display device shown in FIG.

FIG. 9 is a diagram showing the relationship between the main direction of the flow rate of the injected liquid crystal, the shift angle in the normal direction of the smectic layer of the injected liquid crystal, and the display contrast.

FIG. 10 is a diagram for explaining the spread of liquid crystal injected into a liquid crystal cell.

FIG. 11 is a diagram for explaining a position of a liquid crystal injection port.

FIG. 12A is a diagram for explaining a position where a boundary between the injected liquid crystal and the vacuum is substantially parallel to the X axis;
(B) is a diagram showing an example where the position where the boundary between the liquid crystal and the vacuum is substantially parallel to the X axis is on the upper side, and (C) is a diagram in which the boundary between the liquid crystal and the vacuum is almost parallel to the X axis. FIG. 9 is a diagram showing an example of a case where the position is on the lower side.

FIG. 13 is a sectional view showing another example of the structure of the liquid crystal display device according to the embodiment of the present invention.

[Explanation of symbols]

11: transparent substrate (lower substrate), 12: transparent substrate (upper substrate), 13: pixel electrode, 14: active element (TF
T), 15: gate line (scan line), 16: data line (gradation signal line), 17: common electrode, 1
8 ... alignment film, 19 ... alignment film, 20 ... sealing material, 20
A: liquid crystal injection port, 20B: sealing material, 21: liquid crystal, 2
2 ... spacer, 23 ... polarizing plate (lower polarizing plate), 24 ...
Polarizing plate (upper polarizing plate), 25: liquid crystal cell, 51: vacuum chamber, 52: dispenser, 52A: heater, 53
... Lamp heater, 54 ... Vacuum pump, 55 ... Valve, 56 ... Liquid crystal dish, 57 ... Heater, 58 ... Panel heater, 71 ... Scan electrode, 72 ... Signal electrode

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tetsushi Yoshida 5 Casio Computer Co., Ltd. Hachioji Research Laboratory, 2951 Ishikawacho, Hachioji-shi, Tokyo

Claims (6)

[Claims] 1. A pair of substrates having electrodes formed on opposing surfaces and rubbed on at least one of the opposing surfaces, and a frame-shaped sealing material having a liquid crystal injection port and joining the pair of substrates. Injected from the liquid crystal injection port into a region formed by the pair of substrates and the sealant, has a layer structure of a smectic phase, and has a normal direction of a layer and a normal of an end face of the liquid crystal injection port. A liquid crystal device comprising: a liquid crystal of a smectic phase having an intersection angle of 1.5 ° or less; and a sealing material for sealing the liquid crystal injection port. 2. A pair of substrates having electrodes formed on surfaces facing each other, a frame-shaped sealing material having a liquid crystal injection port and joining the pair of substrates, and a pair of substrates and the sealing material. And a liquid crystal of a smectic phase injected from the liquid crystal injection port in a region formed by: a long side of the liquid crystal injection region formed by the pair of substrates and the sealing material is X, and a short side is Y. The number k of the liquid crystal injection ports and the ratio k = Y / P between the position P and the position Y at which the boundary between the injected liquid crystal and the non-injection region becomes substantially parallel to the short side Y are expressed by the following equations (1) and (2) 2. A liquid crystal device, which satisfies 2. ## EQU1 ## n = int (k.X / (2.Y)) int indicates a natural number. 3. The liquid crystal device according to claim 2, wherein the position x _i of the i-th liquid crystal injection port is represented by Expression 3. X _i = X / (2 · i + 1) i = 1,2,..., N 4. A frame having electrodes formed on surfaces facing each other and having a pair of substrates rubbed on at least one of the opposing surfaces, and a liquid crystal injection port, and joining edges of the pair of substrates. Forming a liquid crystal cell composed of: a sealing material of the formula (1), and the liquid crystal of the smectic phase is applied to the liquid crystal cell from the liquid crystal inlet by an angle of intersection with the normal direction of the layer of the smectic phase layer structure of 1.5 A method for manufacturing a liquid crystal device, comprising: a step of injecting a liquid crystal of a smectic phase so as to have a main axis of a flow rate in a direction of not more than °, and a step of sealing the liquid crystal injection port. 5. A frame having a pair of substrates in which electrodes are formed on surfaces facing each other and rubbed on at least one of the opposing surfaces, and a liquid crystal injection port, which joins edges of the pair of substrates. And a step of forming a liquid crystal cell composed of: and a step of injecting a liquid crystal of a smectic phase into the liquid crystal cell from the liquid crystal injection port, comprising: the pair of substrates and the sealing material. X is the long side of the liquid crystal injection region, Y is the short side, the number n of the liquid crystal injection ports, and the positions P and Y are such that the boundary between the injected liquid crystal and the non-injection region is parallel to the short side Y. A ratio k = Y / P satisfies Equation 4 and Equation 5. A method for manufacturing a liquid crystal device, characterized in that: ## EQU4 ## n = int (k × X / (2 × Y)) 5 ≦ k ≦ 6 6. The method according to claim 5, wherein the position x _i of the i-th liquid crystal injection port is represented by Expression 6. X _i = X / (2 · i + 1) i = 1, 2,..., N