JPH0980444A - Production of liquid crystal cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to adequately assure the shape and function as a liquid crystal cell by superposing both electrode substrates on each other via spacers of a large diameter and small diameter and pressurizing both electrode substrates until the spacing therebetween is reduced to the diameter of the small-diameter spacers after injection of liquid crystals. SOLUTION: The spacers 30a of the small diameter and the spacers 30b of the large diameter are respectively sprayed onto the surface of the color filter substrate 10 and the counter substrate 20 is superposed on the color filter substrate 10 via both spacers 30a, 30b and a seal 40, by which an empty cell is formed. The seal 40 is then cured by baking while load is applied thereon in such a manner that the cell gap attains about 5μm which is the diameter of the spacers 30b. The substrates are then arranged in a vacuum state and the smectic liquid crystals are injected into the empty cell. The gap of the liquid crystal cell is held at 5μm by the spacers 30b. The pressure is thereafter applied by a pressurizing jig on both substrates 10 and 20 to deform the spacers 30b so that the cell gap of the liquid crystal cell is held uniformly at 2μm only by the spacers 30a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal cell manufacturing method.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a liquid crystal cell of this type, there is one disclosed in, for example, JP-A-56-146117. That is, a large number of spacer fine particles having a predetermined size are dispersed on one inner surface of both electrode substrates, and a seal is printed in a strip shape on the outer peripheral portion of the inner surface of the other electrode substrate. Then, the two electrode substrates are overlapped with each other through the spacer fine particles and the seal to form an empty cell, the empty cell is placed in a vacuum state, and the liquid crystal injection port of the seal is immersed in the liquid crystal.
After that, the outside of the empty cell is opened to the atmosphere, and liquid crystal is injected into the empty cell based on the pressure difference between the inside and outside of the empty cell to manufacture a liquid crystal cell.

[0003]

By the way, when the liquid crystal is a nematic liquid crystal, the cell gap (distance between both electrode substrates) is 5 μm to 10 μm. Can be injected relatively smoothly. However, when the liquid crystal is a smectic liquid crystal such as a ferroelectric liquid crystal or an antiferroelectric liquid crystal, the cell gap is narrower than that in the case of using the nematic liquid crystal, and is 3 μm or less. Therefore, there occurs a problem that the time required for injecting the smectic liquid crystal into the empty cell after opening to the atmosphere is 5 to 10 times longer than that for injecting the nematic liquid crystal.

On the other hand, it is possible to increase the injection speed V by utilizing the fact that the injection speed V (see FIG. 4) of the liquid crystal that enters the empty cell is given by the following equation (1).

[0005]

[Formula 1] V∝ΔP · d ² / (12 · ΔX · μ) where ΔP represents the pressure difference between the inside and outside of the empty cell, ΔX represents the distance that liquid crystal enters the empty cell, and d is the cell gap. And μ represents the viscosity of the liquid crystal. Then, this number 1
According to the equation, the implantation speed V is proportional to the square of the cell gap d. Therefore, the following method can be considered to improve the implantation speed.

First, a method of increasing ΔP when injecting liquid crystal can be considered. For example, after the empty cell is opened to the atmosphere as described above, the empty cell is placed in a high-pressure atmosphere of about 2 to 6 atm. However, in such a case, due to the high pressure, the space between both electrode substrates is widened and the liquid crystal cell swells. Therefore, even if the liquid crystal injection speed can be increased, the quality of the liquid crystal cell is deteriorated.

Secondly, it is considered that the temperature at the time of injecting the liquid crystal is increased to reduce the viscosity μ. However, in this case, there is a limit to the temperature rise of the other constituent materials, so that there is a limit to reducing the viscosity of the liquid crystal. Therefore,
It is difficult to increase the liquid crystal injection rate by increasing the temperature. Thirdly, it is conceivable that the seal is provided with a plurality of liquid crystal injection ports from different directions. In this case, the liquid crystal injected into the empty cell is displayed at a position where both liquid crystal substrates contact each other. It causes unevenness.
Therefore, even if the injection speed of the liquid crystal can be increased, the display unevenness of the liquid crystal cell is caused.

Therefore, the above method cannot increase the injection speed of the liquid crystal into the empty cell so that the shape and function of the liquid crystal cell can be properly secured. Therefore, in order to deal with the above, the present invention maintains a wide gap between both electrode substrates during liquid crystal injection, and reduces the gap between both electrode substrates after liquid crystal injection to secure an original cell gap. It is an object of the present invention to provide a liquid crystal cell manufacturing method.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the invention described in claims 1 to 6, both electrode substrates (10, 10A, 20, 20A) are made to have a small diameter and a large diameter in the superposing step (S6). The spacers (30a, 30b) are superposed on each other, and then, in a liquid crystal injection step (S8), liquid crystal is injected between the both electrode substrates.

As a result, the distance between the two electrode substrates is maintained at least equal to or larger than the diameter of the large-diameter spacer, so that a wide distance between the two electrode substrates can be secured when injecting the liquid crystal. Therefore, the liquid crystal can be injected into the space between both electrode substrates at a high injection speed. The injection rate can be high. In addition, after the liquid crystal injecting step, in the pressing step (S9), the large diameter spacer (30b) is deformed until the distance between the electrode substrates is reduced to the diameter of the small diameter spacer (30a). Pressurize the electrode substrate.

With this, it is possible to secure the quick injection of the liquid crystal without providing a plurality of liquid crystal injection ports from different directions or to unnecessarily increase the pressure and the temperature to both electrode substrates, and the liquid crystal cell can be provided. The original uniform cell gap can be secured. In such a case, even if the distance between the two electrode substrates when the pressure is applied is as narrow as 3 μm or less as in the invention described in claim 5, the distance between the two electrode substrates is maintained wide as described above when the liquid crystal is injected. High injection rate can be secured.
This is the same even when the liquid crystal is a smectic liquid crystal as in the sixth aspect of the invention.

According to a seventh aspect of the present invention, the small-diameter spacer is made of an elastic resin material so that the small-diameter spacer has a diameter of about 2 μm and the large-diameter spacer has a diameter of about 3 μm to 5 μm. Even if it is formed and the liquid crystal is a smectic liquid crystal, the same function and effect as the invention according to claim 1 can be achieved. Further, as in the invention described in claim 8, the overall distance between both electrode substrates (10A, 20A) formed by curving outwards from the outer peripheral portion to the central portion is reduced to the distance between the both outer peripheral portions. As described above, in the pressing step, even if the central portions of the both electrode substrates are pressed, the same operational effects as the inventions according to claims 1 to 7 can be achieved.

According to the invention of claim 9, in the pressurizing step, until the distance between the portions of the electrode substrates excluding the outer peripheral portions decreases to the diameter of the small-diameter spacer,
Even when pressure is applied to portions of the both electrode substrates excluding the outer peripheral portions, the same operational effects as the inventions according to the first to seventh aspects can be achieved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a manufacturing process of a liquid crystal cell according to the present invention. First, in the color filter substrate forming step S1, the color filter substrate 10 is formed as shown in FIG.

Here, the color filter substrate 10 is
A glass substrate 11 is provided, and a plurality of strip-shaped color filters 12 and light-shielding masks 13 are alternately formed on the inner surface of the glass substrate 11. An overcoat 14 is formed on each of the color filters 12 and each of the light shielding masks 13. This overcoat 14
A plurality of transparent conductive films 15 are formed on the inner surface of the so as to face the plurality of color filters 12. Further, an insulating film 16 and an alignment film 17 are formed on the inner surface of the overcoat 14 with each transparent conductive film 15 interposed therebetween.

On the other hand, in the counter substrate forming step S2, as shown in FIG.
As shown in (b), the counter substrate 20 is formed. In this counter substrate 20, a plurality of transparent conductive films 22 are formed on the inner surface of a glass substrate 21, and an insulating film 23 and an alignment film 24 are formed on the inner surface of the glass substrate 21 via these transparent conductive films 22. Is configured. The plurality of transparent conductive films 22 and the plurality of transparent conductive films 12 form a grid-shaped transparent electrode.

Next, in the spacer spraying step S3,
As shown in FIG. 2A, a small diameter (for example, diameter 2 μ
m) spacer 30a and large diameter (for example, diameter 5 μm)
The spacers 30b are dispersed on the inner surface of the alignment film 17 of the color filter substrate 10. Where the spacer 3
The color filter substrate 1 has a diameter of 0a of 2 μm.
This is because the final cell gap as a liquid crystal cell formed by 0 and the counter substrate 20 is 2 μm. In addition, the final uniform cell gap of the liquid crystal cell is 2μ.
In order to secure m, in the pressurizing step S9 described later, 6
In order to withstand the pressure of atmospheric pressure, the spacer 30a is made of a hard resin material such as silica that is hard to be crushed or a glass material, and the spacer 30a has a dispersion density of 800 pieces /
mm ² to.

Further, the material for forming the spacer 30b is made of a soft elastic resin material which is easily deformed, and the dispersion density is set to 10 pieces / mm ² so as to withstand the atmospheric pressure when the liquid crystal is injected and to be crushed at a pressure of 6 atmospheres. For example, the spacer 30b is preferably a Micro Pale SP type manufactured by Toray Industries, Inc. On the other hand, in the seal printing step S4, the alignment film 2 on the counter substrate 20 is formed.
A seal material 40 (for example, DSES1010 type manufactured by NIPPO ELECTRIC CO., LTD.
Toray XN21 type) is formed by band printing, and in the subsequent pre-baking step S5, the seal 40 is pre-baked and semi-cured at 90 ° C. for 1 hour.

After that, in the superposing step S6, as shown in FIG. 3, the counter substrate 20 is placed on the counter substrate 20 via the spacers 30a and 30b and the seal 40.
To form an empty cell. Next, in the main firing step S7, a seal 4 is applied for 20 minutes at an atmospheric pressure of 100 ° C. while applying a load to the empty cell so that the cell gap becomes about 5 μm which is the diameter of the spacer 30b (see FIG. 7).
0 is main-baked to be fully hardened.

Then, in the liquid crystal injection step S8, the color filter substrate 10 and the counter substrate 20 which are stacked as described above are placed in a vacuum state in a vacuum chamber, and a seal 40 is placed.
The liquid crystal inlet 41 (see FIG. 4) is immersed in the smectic liquid crystal adopted as the liquid crystal. After that, the inside of the vacuum chamber, that is, the outside of the empty cell is released to atmospheric pressure. Then, the smectic liquid crystal L (see FIG. 5) is sealed by the seal 40 based on the pressure difference between the inside and the outside of the color filter substrate 10 and the counter substrate 20.
It is injected into the empty cell through the liquid crystal injection port.

At this time, atmospheric pressure is applied to the outside of the empty cell, but since each spacer 30b is formed of an elastic resin material capable of withstanding the atmospheric pressure, the cell gap of the liquid crystal cell is 5 μm due to each spacer 30b. Retained. Therefore, the injection speed of the smectic liquid crystal L is as high as the injection speed of the nematic liquid crystal. Since this injection reduces the viscosity of the smectic liquid crystal L,
It is performed at a temperature of about 0 ° C.

When the injection of the smectic liquid crystal L is completed in this way, in the pressurizing step S9, both pressurizing treatments are applied to the color filter substrate 10 and the counter substrate 20 of the empty cell (that is, the liquid crystal cell) in which the smectic liquid crystal L is injected. Tool S (Fig. 5
See 6) and apply a pressure of 6 atm at 150 ° C. Therefore, each spacer 30b is elastically deformed as shown in FIG. 5, and the distance between the color filter substrate 10 and the counter substrate 20 is gradually reduced. Then, each spacer 30b is crushed by the deformation exceeding its elastic limit, and the distance between the color filter substrate 10 and the counter substrate 20 becomes equal to the diameter of each spacer 30a (see FIG. 7). This allows
The liquid crystal cell is uniformly held at 2 μm only by the spacers 30a having a cell gap of 800 cells / mm ² (see FIG. 6).

After that, in the sealing step S10, the liquid crystal injection port 41 of the seal 40 is sealed with an adhesive. This completes the manufacture of the liquid crystal cell. 8 and 9 show a first modification of the above embodiment. In this first modification, a color filter substrate 10A is formed in place of the color filter substrate 10 in the color filter substrate forming step S1, while an opposite substrate 20A is formed in place of the opposite substrate 20 in the opposite substrate forming step S2. .

Here, the color filter substrate 10A and the counter substrate 20A are respectively, as shown in FIG. 8, except that they are convexly curved outward.
0 and the same structure as the counter substrate 20. In the spacer spraying step S3, the color filter substrate 10A
The spacers 30a are sprinkled on the inner surface of the above, and the spacers 30b are sprinkled by masking the outer peripheral portion of the inner surface corresponding to the seal 40A.

In the next seal printing step S4, the seal material 40A mixed with the spacer 30a is printed. Also,
In the superposing step S6, the color filter substrate 1
As shown in FIG. 8, the seal 40A and the spacer 30 are arranged so that the 0A and the counter substrate 20A are convex outward.
a and 30b are overlaid.

Here, of the cell gap between the color filter substrate 10 and the counter substrate 20, the gap region corresponding to the seal 40A (hereinafter referred to as the seal-corresponding gap region) is 2 μm. In addition, the gap area (inner gap) located inside the gap area corresponding to the seal
Is the color filter substrate 10A and the counter substrate 2 described above.
Due to the convex shape of 0 A, it increases from 2 μm to 5 μm from the seal corresponding gap region to the center of the inner gap region.

Then, in the same manner as described in the above embodiment, in the liquid crystal injection step S8, the smectic liquid crystal L is injected into the empty cell through the liquid crystal injection port of the seal 40A. In this case, since the region other than the seal-corresponding gap region of the empty cell is as wide as 2 μm to 5 μm, the smectic liquid crystal L is quickly injected into the empty cell. After injecting in this way, in the pressurizing step S9, several 10's are applied to each outer surface portion in the seal-corresponding gap region of the liquid crystal cell.
A seal-corresponding gap region side adjusting member R made of rubber or paper having a thickness of μm is laid respectively so that a pressure is applied to the inner gap region (see FIG. 8). Then, each of the adjusting members R and the color filter substrate 10A
Further, the central area of the liquid crystal cell is thinned as shown in FIG. 9 by pressurizing each central area of the counter substrate 20B at 6 atmospheres and 150 ° C. to make the cell gap 2 μm. In this case, since the spacer 30a is included in the seal 40A,
The spacing of the cell gap in the seal-corresponding gap region does not decrease below 2 μm.

Therefore, also with this first modification, the same operational effects as those of the above-described embodiment can be achieved. 10 and 11 show a second modification of the above embodiment. In the second modified example, in the pressurizing step S11, a region corresponding to the seal 40 of the liquid crystal cell (hereinafter referred to as a seal corresponding region) so that the load is concentrated on the centers of the color filter substrate 10 and the counter substrate 20. ) To inward 1
Color filter substrate 10 and counter substrate 2 separated by about cm
Each adjustment member R1 (see FIG. 10) made of rubber or paper having a thickness of several tens of μm is laid in each area of 0 (hereinafter, referred to as a central area), and the color filter substrate 10 and the counter substrate 20 are provided through these adjustment members R1. 6 atmospheres 150 ℃ in each central area
Apply pressure from the outside. As a result, a cell gap of 2 μm is formed by leaving only the seal corresponding region (FIG. 1).
1).

Therefore, also with this second modification, the same operational effects as those of the above-described embodiment can be achieved. In carrying out the present invention, the present invention is not limited to the method for manufacturing a liquid crystal cell having a color filter substrate, and the present invention is applied to a method for manufacturing a liquid crystal cell having a narrow cell gap even in a monochrome liquid crystal cell. May be. Thereby, the same operation and effect as the above embodiment can be achieved.

[Brief description of drawings]

FIG. 1 is a process drawing showing a method for manufacturing a liquid crystal cell according to the present invention.

FIG. 2 is a cross-sectional view showing a structure of a color filter substrate and a state in which spacers having a diameter of 2 μm and spacers having a diameter of 5 μm are scattered on the inner surface of an alignment film of the color filter substrate, the structure of a counter substrate and the alignment film of a counter substrate. It is sectional drawing which shows the state which printed the seal on the inner surface outer peripheral part.

FIG. 3 is a cross-sectional view of an empty cell in which a counter substrate is superposed on a color filter substrate with a seal and each spacer interposed therebetween.

FIG. 4 is a plan view of an empty cell.

FIG. 5 is a cross-sectional view showing a process of thinning toward a 2 μm spacer by applying pressure between a color filter substrate in which smectic liquid crystal is injected and a counter substrate.

FIG. 6 is a cross-sectional view showing a state in which a 5 μm spacer is crushed by applying pressure between a color filter substrate into which a smectic liquid crystal is injected and a counter substrate.

FIG. 7 is a graph showing a relationship between a cell gap of a liquid crystal cell and a liquid crystal cell manufacturing process.

FIG. 8 is a cross-sectional view of a liquid crystal cell showing a first modification of the above embodiment.

9 is a cross-sectional view showing a state in which the liquid crystal cell of FIG. 8 is pressurized to a cell gap of 2 μm.

FIG. 10 is a cross-sectional view of a liquid crystal cell showing a second modification of the above embodiment.

11 is a cross-sectional view showing a state in which the liquid crystal cell of FIG. 8 is pressed against the liquid crystal cell until the area of the cell gap excluding the portion corresponding to the seal becomes 2 μm.

[Explanation of symbols]

10, 10A ... Color filter substrate, 20, 20A
... Counter substrates, 30a, 30b ... Spacers, 4
0, 40A ... Seal, L ... Smectic liquid crystal,
S3 ... Spacer spraying step, S6 ... Overlaying step, S8 ... Liquid crystal injecting step, S9 ... Pressurizing step.

Claims (9)

[Claims] 1. Both electrode substrates (10, 10A, 20, 20)
A step (S6) of superposing (A) on each other through the small-diameter spacers (30a, 30b) and a liquid-crystal injection step (S8) of injecting a liquid crystal (L) between the electrode substrates. ) And, after this step, pressurizing the both electrode substrates so as to deform the large diameter spacer (30b) until the distance between the both electrode substrates decreases to the diameter of the small diameter spacer (30a). A method of manufacturing a liquid crystal cell, comprising the step (S9). 2. The method of manufacturing a liquid crystal cell according to claim 1, wherein the dispersion density of the small-diameter spacers is higher than the dispersion density of the large-diameter spacers. 3. The dispersion density of the small-diameter spacers is a value that can withstand the pressure at the time of pressurization in the pressurizing step, while the dispersion density of the large-diameter spacers can withstand the atmospheric pressure. It is a value, The liquid crystal cell manufacturing method of Claim 1 or 2 characterized by the above-mentioned. 4. The liquid crystal cell manufacturing method according to claim 1, wherein, in the pressing step, the large-diameter spacer is crushed by pressing the electrode substrates. 5. The method of manufacturing a liquid crystal cell according to claim 1, wherein the space between the two electrode substrates is 3 μm or less due to the pressure applied in the pressure applying step. 6. The method for producing a liquid crystal cell according to claim 5, wherein the liquid crystal is a smectic liquid crystal. 7. The small-diameter spacer has a diameter of about 2 μm, and the large-diameter spacer is made of an elastic resin material so as to have a diameter in the range of about 3 μm to 5 μm, and
The liquid crystal cell manufacturing method according to claim 1, wherein the liquid crystal is a smectic liquid crystal. 8. The electrode substrates are formed so as to curve outward from each other from the outer peripheral portion to the central portion thereof, and in the pressurizing step, the entire distance between the both electrode substrates is equal to the distance between the outer peripheral portions. The liquid crystal cell manufacturing method according to claim 1, wherein pressure is applied to each central portion of the both electrode substrates so as to decrease. 9. In the pressing step, pressure is applied to the portions of the both electrode substrates excluding the outer peripheral portions until the distance between the portions of the both electrode substrates excluding the outer peripheral portions is reduced to the diameter of the small-diameter spacer. The liquid crystal cell manufacturing method according to claim 1, wherein the liquid crystal cell manufacturing method is a liquid crystal cell manufacturing method.