JPH1048585A - Method for manufacturing liquid crystal element and empty cell substrate used therefor - Google Patents

Abstract

(57) [Problem] To improve the dimensional accuracy and facilitate the injection and sealing of liquid crystal to improve the productivity when manufacturing a plurality of small liquid crystal elements by a manufacturing method. A first substrate (1) having an empty cell integrally formed therein has a groove (6) penetrating therethrough, and the groove (6) has an inlet (5) for an empty cell.
Are connected, and the liquid crystal 7 is supplied to the groove 6 to inject the liquid crystal, and the sealing material is poured into the groove to seal the injection port 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal element and an empty cell substrate used for the method.

[0002]

2. Description of the Related Art A liquid crystal element utilizes characteristics of liquid crystal, and a display element, a polarization diffraction element, a transmittance modulation element, and the like have been proposed, and some of them have been widely used. These liquid crystal elements are manufactured using two substrates on which electrodes, diffraction gratings, alignment films and the like are formed.

In this case, in order to improve the productivity, a plurality of empty cells are integrally formed by bonding two substrates with a gap therebetween via a sealing material, and then a liquid crystal is injected from an injection port of the plurality of empty cells. Then, the injection port is sealed and cut and separated into individual liquid crystal elements to manufacture a liquid crystal element.

[0004] The sealing material is applied on one of the substrates by screen printing or a dispenser. An opening is formed in a part of the sealing material, and after the two substrates are bonded to each other, the opening is used as a liquid crystal injection port. Degas the air in the empty cell in a vacuum, immerse this inlet in the liquid crystal, or drop the liquid crystal at the end of the inlet, etc.
A method of filling a liquid crystal in an empty cell has been conventionally used.

When the liquid crystal element is small, it is advantageous to increase the substrate size so that a plurality of liquid crystal elements can be formed, from the viewpoints of reduction of material cost, simplification of handling, improvement of yield, and the like. However, in the conventional liquid crystal element and the method of manufacturing the same, it is necessary to use the opening side of the sealing material as the opening end in order to inject the liquid crystal. Therefore, when the size of the substrate is increased and the number of liquid crystal elements is increased, the bonded substrate must be cut into an elongated stick shape, and then the liquid crystal must be injected and sealed. And the yield was poor.

In addition, the liquid crystal injection port is sealed by applying a sealing material to the end face. However, the sealing material inevitably has a shape protruding from one end face, and is often required for a small liquid crystal element. It is disadvantageous in maintaining dimensional accuracy. In addition, the application of the sealing material to the end surface is likely to cause the sealing material to sneak into the outer surface of the substrate, which may be an obstacle when attaching a liquid crystal element or forming a composite with other members. It took time to scrape off the sealing material.

Further, a method of injecting liquid crystal by providing a through hole in a substrate has been conventionally proposed. However, when a liquid crystal element is small, it is necessary to provide a through hole in each liquid crystal cell and inject the liquid crystal.
In view of the processing, the supply of the liquid crystal, and the completion of the injection, the productivity is poor, and there is a problem of contamination of the substrate surface by extra liquid crystal.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned disadvantages of the prior art and to provide a method of manufacturing a liquid crystal element having no protruding sealing material and good productivity, and an empty cell substrate used therefor. To provide.

[0009]

According to the present invention, after a plurality of empty cells are integrally formed by bonding two substrates with a gap therebetween via a sealing material except for an injection port, a plurality of empty cells are injected. In a method for manufacturing a liquid crystal element in which liquid crystal is injected from an inlet, and the injection port is sealed and cut and separated into individual liquid crystal elements, one of the substrates integrally formed with empty cells has a groove penetrating therethrough. It has a structure where the inlet of the empty cell is connected,
Provided is a method for manufacturing a liquid crystal element, characterized in that a liquid crystal is supplied to the groove to inject the liquid crystal and an injection port in the groove is sealed.

A method of manufacturing a liquid crystal element, in which liquid crystal is supplied to the groove and liquid crystal is injected using the groove as a liquid crystal reservoir,
And, a seal is formed so that the groove is surrounded by a sealing material, liquid crystal is injected using the groove as a liquid crystal reservoir, and then a sealing material is poured into the groove to seal the injection port, and thereafter, A method for manufacturing a liquid crystal element which is cut into individual liquid crystal elements by cutting with a cutting means, a method for manufacturing a liquid crystal element in which one of the substrates is a substrate on which a lattice-shaped uneven portion is formed, and a method for cutting the same Provided is a method for manufacturing a liquid crystal element in which two substrates are sometimes cut so that a step is formed at a side where an injection port is present.

[0011] Further, in an empty cell substrate in which a plurality of empty cells are integrally formed by bonding two substrates together with a gap therebetween through a sealing material except for an injection port, one of the substrates in which the empty cells are integrally formed is formed. There is provided an empty cell substrate having a structure in which a penetrating groove is provided and an injection port of an empty cell is connected to the groove.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has a structure in which one side of a substrate integrally formed with empty cells has a penetrating groove, and the groove is connected to an injection port of the empty cell. Is supplied to inject the liquid crystal, so that even a small liquid crystal element can inject the liquid crystal very easily. Furthermore, since the injection port can be sealed using the groove, the reliability of the sealing is improved.

FIG. 1 is a perspective view showing a state before assembling a substrate used in a method of manufacturing a liquid crystal element according to the present invention. In FIG. 1, 1 is a first substrate, 2 is a second substrate, 3 is a liquid crystal cell, 4 is a sealing material, 5 is an inlet, and 6 is a groove.

The first substrate 1 and the second substrate 2 are made of glass,
A substrate such as plastic used for a normal liquid crystal element is used. The present invention is particularly suitable for manufacturing a liquid crystal element in which a liquid crystal diffraction grating is formed by using a substrate in which one of the substrates is formed with lattice-like irregularities. These two substrates are used by forming an alignment film such as SiO or polyimide and an electrode such as ITO as necessary.

In the present invention, the first substrate 1 is formed with a groove 6 penetrating the substrate. The groove 6 is formed such that when two substrates are pressure-bonded to form a liquid crystal cell, the injection port 5 which is an opening of the sealing material 4 is connected to the groove. Normally, it may be formed in a straight line as shown in FIG. 1, but may be formed in a U-shaped or S-shaped groove. This groove is
When the surroundings are completely surrounded by walls and the liquid crystal is supplied,
It is preferable that this groove be structured so as to serve as a liquid crystal reservoir.

In FIG. 1, one groove corresponds to one row of empty cells, but two adjacent rows of empty cells correspond to one injection port.
The arrangement may be such that the two grooves face each other.
The groove 6 may be formed by a method such as sand blast, wet sand blast, and ultrasonic honing. In the present invention, since such a groove 6 is provided, it is possible to inject an empty cell array of three or more rows without cutting it with a stick.

In the case where the substrate is provided with a lattice-like unevenness serving as a diffraction grating, the unevenness is preferably provided not on the first substrate 1 provided with the groove 6 but on the second substrate 2. It is preferable that the longitudinal direction of the lattice-shaped unevenness is perpendicular to the side where the injection port of the liquid crystal cell is provided, so that the liquid crystal can be smoothly injected.

The projections and depressions of the lattice shape serving as the diffraction grating make the projections substantially coincide with the ordinary light refractive index or the extraordinary light refractive index of the liquid crystal. Thus, the liquid crystal element provided with the lattice-like irregularities becomes an anisotropic diffraction grating that functions as a diffraction grating only for light in a specific polarization direction.

Such an anisotropic diffraction grating is provided between the laser light source, the photodetector and the optical recording medium, and has a λ on the optical recording medium side.
A phase difference plate such as a / 4 plate is laminated and arranged, and is used as an optical head device. By using this anisotropic diffraction grating, the light use efficiency is greatly improved.

As a sealing material and a sealing material, an epoxy resin, an acrylic resin, or the like having excellent airtightness and moisture resistance is used. In general, a columnar or spherical glass or resin spacer is mixed with the sealing material so that the gap between the two substrates after bonding is constant. This sealing material may be applied by a known sealing material applying means such as screen printing or a dispenser. Since the sealing material of the injection port is supplied into the groove 6, a dispenser or the like is preferable.

FIG. 1 shows a substrate on which 3 × 4 liquid crystal elements are formed. However, the number is not limited to this, and may be appropriately changed depending on the dimensions of the liquid crystal element to be manufactured and the substrate size that can be handled by a liquid crystal element manufacturing apparatus. .

In this example, the sealing material of each liquid crystal cell is connected so as to form a closed space below the groove. By doing so, the bottom of this groove can be used as a closed liquid crystal reservoir and a mold for the injection port sealing material,
Since the supply of the liquid crystal and the supply of the sealing material are facilitated, the productivity is improved.

If the gap is small, the leakage of the liquid crystal and the sealing material is small, so that it can be used even if the sealing material is not completely continuous. For example, the sealing material of the liquid crystal cell at the center of each column in FIG. 1 may be separated from the sealing materials of other liquid crystal cells. Further, in this example, a state is shown in which the sealant is applied to the second substrate, but this may be applied to the first substrate or to both substrates.

The two substrates are superimposed, pressed together, and the sealing material is cured by heating or irradiation with ultraviolet rays to be integrated. As a result, a substrate in which a number of empty cells are formed on a pair of substrates is formed.

FIG. 2 is a front view of an example of the empty cell substrate thus manufactured. FIG. 3 is a sectional view of the AA plane. FIG.
The same parts as in FIG. In FIGS. 2 and 3, B to G are cut portions.

In the horizontal direction of FIG. 2, the cutting may be performed at the point B. When the electrodes are provided and the terminals are taken out on the upper and lower sides, the cutting position may change depending on the two substrates. The other cut portion is any one of C to G or a plurality thereof.

FIG. 4 is a front view of an example in which the pattern of the sealing material is changed. The portion of the liquid crystal cell adjacent to the sealing material is a common sealing material 8. In the example as shown in FIG. 2, when cutting for separating into individual liquid crystal elements, a method of making a cut line and breaking, or a method of cutting with a cutting means such as a diamond wheel can be used. If the sealing material has a narrow width, even if it is broken, it hardly affects the sealing of the liquid crystal element.

In the example shown in FIG. 4, since the width of the sealing material 8 is increased at the boundary between adjacent liquid crystal cells, the sealing material 8 cannot be split in the direction B. In this case, cutting is performed by a cutting means such as a diamond wheel. Cutting by this cutting means is more time-consuming and less productive than folding, but has good dimensional accuracy and is suitable for use as a small anisotropic diffraction grating.

Such an empty cell substrate is formed, placed in a closed container, evacuated in vacuum, and supplied with liquid crystal 7 from the position above the groove 6 in FIG. 3 to perform vacuum injection. In this case, the liquid crystal is supplied into the groove 6. What is necessary is just to supply by the dispenser etc. to the vicinity of the inlet. Since the liquid crystal is supplied into the groove 6, the substrate surface is hardly contaminated with the liquid crystal, and the loss of the liquid crystal is small. Also, for an empty cell group of three or more columns,
Can be injected without cutting into sticks.

As shown in FIG. 1, in the case of the structure in which the groove is surrounded by the sealing material, liquid crystal can be dropped at one end of the groove 6 and injected using the groove as a liquid crystal reservoir.
Since liquid crystal can be supplied to many empty cells in one row at a time, productivity is good. That is, it is not necessary to drop the liquid crystal in accordance with the injection port of each liquid crystal cell. Subsequent sealing of the injection port may be achieved simply by pouring the sealing material into the groove, and the productivity is good. This advantage is more advantageous as the liquid crystal element is smaller.

In the present invention, the sealing material serves as a container,
As shown in FIG. 1, it is more advantageous that the groove is surrounded by a wall and has a container shape when the groove is used as a liquid crystal reservoir. In the case where there is considerable room for truncation around the substrate, even if there are no walls at both ends of the groove and both ends are open, the liquid crystal does not flow due to surface tension, and the same effect is obtained.

That is, the liquid crystal 7 dropped into the groove 6 flows in the longitudinal direction of the groove 6 and spreads, and flows into the gap between the liquid crystal cells 3 through the injection port 5 of the empty cell communicating with the groove 6. The liquid crystal dripping amount per one groove is set to be slightly larger than the total capacity of the liquid crystal cells communicating with one groove 6.

In the case of a small liquid crystal element, the liquid crystal is often filled only by the capillary phenomenon from the injection port. After the liquid crystal is dropped, the vacuum is maintained for an appropriate time, and then an inert gas such as nitrogen is introduced into the closed vessel to return to the atmospheric pressure, and the liquid crystal cell substrate into which the liquid crystal has been injected is taken out of the closed vessel.

By injecting the liquid crystal through the penetrating groove 6, it is possible to inject the liquid crystal into a plurality of liquid crystal elements without cutting the pair of bonded substrates into an elongated stick shape. Therefore, unlike the conventional method, the handling is easy and the improvement of the yield can be expected.

Next, after the liquid crystal remaining on the surface of the substrate filled with the liquid crystal and in the groove 6 is wiped off with dust-free cotton or the like, the filling port in the groove is sealed with a sealing material by a dispenser or the like. Also in this case, sealing can be performed with high productivity by moving the dispenser at a constant speed in the longitudinal direction of the groove 6 and uniformly applying the sealing material in the groove 6.

In this case, the application speed of the sealing material and the moving speed of the dispenser are adjusted so that the sealing material does not protrude from the groove 6 and has a sufficient sealing amount. After the application of the sealing material, the sealing material is cured by heating or ultraviolet irradiation. By applying the sealing material along the groove, sealing without protruding can be performed. Further, the liquid crystal cells in three or more rows can be sealed without cutting, so that productivity is good.

In particular, in the case of a structure in which the groove is surrounded by the sealing material as shown in FIG. 1, it is sufficient to pour the sealing material into the groove 6, and the productivity is good. In this case, since the sealing material is formed over the entire length in the groove, cutting is not performed by cutting but by cutting means such as a diamond wheel.

The cutting is performed by cutting the liquid crystal cell substrate into which the liquid crystal is injected and the injection port is sealed with a cutting means such as a diamond wheel, or by using a scriber, a breaker or the like to break the liquid crystal cell substrate. Then, it is cut at positions B and C to G to separate into individual liquid crystal elements. The cutting position is C
The shape of the manufactured liquid crystal element changes depending on the positions of G.

FIG. 5 is a cross-sectional view of the liquid crystal element cut at the position E in FIGS. 2 and 3. In FIG. 5, since the substrate is cut at the position of E, the size of the substrate is X at both ends of the upper and lower substrates.
Out a difference in only ₁ and X ₂ dimensions, it constitutes a step. When the step is formed on the injection port side in this manner, the sealing material 9 sealing the injection port 5 is connected to the end surface of the upper first substrate 1 and the lower second substrate 1.
Is adhered to the upper surface of the substrate 2 and the sealing is performed firmly.

A small anisotropic diffraction grating having an outer dimension of about 20 mm square or less is incorporated in an optical head device. In this case, precise alignment is required, and dimensional accuracy of the liquid crystal element is required. For this reason, since four directions are cut by a cutting means such as a diamond wheel, the structure as shown in the drawing, particularly FIG. 5, is advantageous.

[0041]

EXAMPLE A glass substrate was prepared as a first substrate and a second substrate, and 28 (7 × 4) liquid crystal elements were fabricated. The size inside the seal of each liquid crystal cell is approximately 10 mm
Corners.

On the inner surface side of the second substrate, a 1.4 μm SiON-based thin film having a refractive index of about 1.5 was laminated and formed into a diffraction grating shape with a pitch of 5 μm and a depth of 1.4 μm by photolithography. The longitudinal direction of this diffraction grating was aligned with the direction orthogonal to the side where the injection port was provided. A polyimide film was formed on the surface having the irregularities, and rubbed along the longitudinal direction of the diffraction grating.

A sealing material obtained by mixing a glass fiber spacer with an epoxy resin was printed on the substrate by screen printing. The diameter of this spacer was adjusted so that the substrate gap at the projection of the diffraction grating was 6 μm. The sealing material had a pattern as shown in FIG. 1 so as to form individual empty cells except for the injection port and to connect between adjacent cells.

On the first substrate, four penetrating grooves were formed. Each of the grooves was linear as shown in FIG. 1, both ends were walled, and the periphery was surrounded by a wall. A polyimide film was formed on the inner surface side, and rubbed along the longitudinal direction of the diffraction grating when it was superimposed on the second substrate.

The two substrates were arranged so that the alignment film surfaces face each other, overlapped each other so that the substrate gap at the convex portion of the diffraction grating was 6 μm, and heated and pressed to produce an empty cell substrate. . Next, the empty cell substrate was placed in a vacuum vessel, and the air in the empty cell was degassed by reducing the pressure. Next, a nematic liquid crystal having a positive dielectric anisotropy was supplied into the four grooves by a dispenser, and the liquid crystal was stored in the four grooves. In this state, the pressure in the vacuum vessel was released, nitrogen gas was introduced, the pressure was returned to atmospheric pressure, and liquid crystal was injected.

Next, the liquid crystal adhered in the groove and on the substrate surface was removed, and a sealing material was poured into the groove and supplied to seal the injection port. Thereafter, the substrate was cut at positions B and E in FIGS. 2 and 3 with a diamond wheel to separate the substrates into individual liquid crystal elements.

[0047]

According to the present invention, the liquid crystal can be easily injected by providing a penetrating groove in one of the substrates of the liquid crystal element and connecting an injection port provided in a part of the sealing material of the liquid crystal cell to this groove. And productivity is improved. In addition, since the injection port can be sealed with a sealing material in this groove, the sealing material does not protrude, so that mounting and compounding are easy, and external dimension accuracy is improved. It has the effect of individualization. In particular, it is suitable for a small liquid crystal element. The present invention can be applied to various applications within a range that does not impair the effects of the present invention.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state before assembling a substrate used in a method for manufacturing a liquid crystal element of the present invention.

FIG. 2 is a front view of an example of an empty cell substrate according to the present invention.

FIG. 3 is a sectional view taken along the line AA of FIG. 2;

FIG. 4 is a front view of another example of the empty cell substrate of the present invention.

FIG. 5 is a cross-sectional view of the liquid crystal element taken along the line AA in FIG. 2 and FIG. 3;

[Explanation of symbols]

 1: first substrate 2: second substrate 3: liquid crystal cell 4: sealing material 5: injection port 6: groove 7: liquid crystal 8: sealing material 9: sealing material

Claims (5)

[Claims] 1. A plurality of empty cells are integrally formed by bonding two substrates with a gap therebetween via a sealing material except for an injection port, and then injecting liquid crystal from the injection ports of the plurality of empty cells. In a method for manufacturing a liquid crystal element in which an entrance is sealed and cut and separated into individual liquid crystal elements, one of substrates on which empty cells are integrally formed has a penetrating groove, and the injection port of the empty cell is connected to the groove. A liquid crystal is supplied to the groove to inject the liquid crystal, and the injection port in the groove is sealed. 2. A seal is formed such that the groove is surrounded by a sealing material. Liquid crystal is injected using the groove as a liquid crystal reservoir, and then a sealing material is poured into the groove to seal the injection port. 2. The method for manufacturing a liquid crystal element according to claim 1, wherein the liquid crystal element is cut into individual liquid crystal elements by a cutting means. 3. The method for manufacturing a liquid crystal element according to claim 1, wherein one of the substrates is a substrate on which a lattice-shaped uneven portion is formed. 4. The method for manufacturing a liquid crystal element according to claim 1, wherein the two substrates are cut such that a step is formed at a side where the injection port exists at the time of cutting. 5. An empty cell substrate in which a plurality of empty cells are integrally formed by bonding two substrates together with a gap except for an injection port through a sealing material, wherein one of the substrates on which the empty cells are integrally formed is formed. An empty cell substrate, having a structure having a penetrating groove, wherein an inlet of an empty cell is connected to the groove.