JP2009216887A - Method of manufacturing liquid crystal cell and liquid crystal cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a liquid crystal cell capable of preventing a seal material from being eluted in liquid crystal and allowing the manufacture with high-quality at lower costs than conventional methods by forming a seal barrier by a simple manufacturing process in a liquid crystal dripping system, and to provide the liquid crystal cell. <P>SOLUTION: The method includes: a resin material application step of applying a resin material on a surface of one transparent substrate; a shape transfer step of forming a seal barrier shape as well as an alignment shape by pressing a die against the resin material; a seal material forming step of forming the seal material on an outer area of the seal barrier; a liquid crystal dripping step of dripping the liquid crystal in an inside area of the seal barrier in the one transparent substrate; and a substrate bonding step of bonding the other transparent substrate to the one transparent substrate via the seal material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a liquid crystal cell, in which two transparent substrates on which a transparent electrode and an alignment film are formed face each other at a predetermined interval, and the inner space of the cell in which the outer periphery is joined with a sealing material is filled with liquid crystal, And a liquid crystal cell.

  Some optical pickup devices for optical discs are configured to correct aberrations using liquid crystal optical elements, but in order to increase the recording density on the discs, downsizing and cost reduction of optical pickup devices are required. Improvements in liquid crystal optical elements are also progressing. Here, the external size of the liquid crystal optical element applied to the optical pickup device is, for example, about 5 mm × 5 mm.

  In recent years, in order to reduce the cost, a liquid crystal dropping method has attracted attention as a manufacturing method of a liquid crystal cell instead of a conventional vacuum injection method, and is applied not only to a large liquid crystal cell but also to a small liquid crystal cell. This is because conventional processes such as liquid crystal injection and sealing work are not necessary, and the cost can be reduced.

  In this liquid crystal dropping method, an uncured sealing material comes into contact with the liquid crystal during the period from the liquid crystal dropping in the inner region of the ring-shaped sealing material to the curing of the sealing material by ultraviolet irradiation after the substrates are bonded together, There is a problem that the sealing material dissolves into the liquid crystal and degrades the liquid crystal. In particular, in a small liquid crystal cell such as a liquid crystal optical element, since the interval between the liquid crystal dripped in the seal inner region and the uncured seal material is narrowed, various methods for minimizing contact between the two have been studied ( For example, see Patent Document 1).

  By providing a seal barrier having a pattern parallel to the seal on the inner side of the seal by the method for manufacturing a liquid crystal cell described in Patent Document 1, it is possible to prevent the uncured seal material from eluting into the liquid crystal. Can do. Thereby, since the alignment state around the seal is also stabilized, display defects of the liquid crystal cell can be prevented in advance. There are a photolithographic method and a printing method for forming the seal barrier, and a material such as photosensitivity or thermosetting can be used as the material of the seal barrier in accordance with the forming method.

  Here, in the printing method, it is difficult to manage the height accuracy of the seal barrier that leads to the cell gap accuracy at the time of completion, and it cannot be employed in a method for manufacturing a small liquid crystal cell. Therefore, in the following description, a manufacturing method by photolithography will be described as an example. 3 and 4 are schematic views showing a manufacturing process of a conventional liquid crystal cell by a liquid crystal dropping method.

  First, as shown in FIG. 3A, a photosensitive resin 10 is applied on a first transparent substrate 1 on which a transparent electrode 2 is previously formed by spin coating or the like. Next, as shown in FIG. 3B, the photosensitive resin 10 is patterned using photolithography to form the seal barrier 5.

  Next, as shown in FIG. 3C, the alignment film material is applied to the first transparent substrate 1 by offset printing or the like and then baked to form the alignment film 9. Next, as shown in FIG. 3D, the surface on which the alignment film 9 is formed is pressed against a rotating roll 11 around which a rubbing cloth is wound to perform a rubbing process. This is to provide a function for aligning the liquid crystal.

Next, as shown in FIG. 4E, a ring-shaped sealing material 6 made of an ultraviolet curable resin and mixed with spacers is formed on the outside of the formed seal barrier 5 by a method such as a screen printing method. Form. Next, as shown in FIG. 4 (f), a predetermined amount of liquid crystal 7 is dropped onto the inner regions of the sealing material 6 and the sealing barrier 5 by a dispenser. Then, in the vacuum chamber, as shown in FIG. 4G, the electrode forming surfaces of the first and second transparent substrates 1 and 8 face each other and overlap each other. Cell thickness. Next, the conventional liquid crystal cell is completed by irradiating the bonded substrates with ultraviolet rays to cure the sealing material 6.

JP 2002-350873 A (page 3, FIG. 1)

  However, in order to form the seal barrier 5 by the conventional manufacturing method, a photolithography method using the photosensitive resin 10 must be adopted, so that the manufacturing process of the liquid crystal cell becomes long and the manufacturing cost is high. There was a problem of becoming.

  Therefore, the present invention solves the above-mentioned problems, and can prevent the sealing material from dissolving in the liquid crystal by forming a seal barrier by a simple manufacturing process in the liquid crystal dropping method. It is another object of the present invention to provide a method for manufacturing a liquid crystal cell and a liquid crystal cell that can be manufactured at a lower cost than conventional methods.

  In order to solve the above problems, the liquid crystal cell manufacturing method of the present invention basically employs the manufacturing method described below.

  The manufacturing method of the present invention is a method for manufacturing a liquid crystal cell in which a liquid crystal is sandwiched between one transparent substrate and another transparent substrate via a ring-shaped sealing material, and a seal barrier is disposed on an inner wall surface of the seal in contact with the liquid crystal. About. And this manufacturing method has the shape transfer process which forms a seal | sticker barrier with a resin material application | coating process which apply | coats a resin material to one transparent substrate surface, and presses a type | mold to a resin material. Further, following this step, a sealing material forming step of forming a sealing material in the outer region of the seal barrier, a liquid crystal dropping step of dropping liquid crystal in the inner region of the seal barrier in one transparent substrate, and the other transparent substrate And a substrate bonding step of bonding to one transparent substrate via a sealing material.

  In the shape transfer step, it is preferable to form the alignment shape and the seal barrier at the same time.

  The liquid crystal cell of the present invention is a liquid crystal cell in which a liquid crystal is sandwiched between one transparent substrate and another transparent substrate via a ring-shaped sealing material, and a seal barrier is disposed on an inner wall surface of the seal in contact with the liquid crystal. The material and the seal barrier are formed of the same resin material by shape transfer using a mold.

  According to the present invention, it is not necessary to perform complicated photolithography for forming the seal barrier. In addition, according to the present invention, since the formation of the seal barrier and the formation of the alignment film can be performed simultaneously, the manufacturing process of the liquid crystal cell can be simplified. And the liquid crystal cell manufactured at the process of this invention becomes a high quality element, and can reduce the manufacturing cost by replacing with the shape transfer process by imprint (embossing) from a photolithography process.

In the present invention, since the alignment film is not rubbed as in the conventional process for aligning the liquid crystal, impurities are not mixed into the liquid crystal from a rubbing cloth or the like. The improvement of sex can be expected.

  Hereinafter, the manufacturing method of the liquid crystal cell of this invention and the structure of the liquid crystal cell formed by this manufacturing method are demonstrated using drawing. 1 (a) to 1 (e) are drawings showing a manufacturing process of a liquid crystal cell of the present invention.

  As shown in FIG. 1A, an ultraviolet curable resin 3 made of an acrylic transparent resin such as a modified acrylate is applied to the surface of the first transparent substrate 1 on which the transparent electrode 2 is patterned. The UV curable resin 3 is applied by spin coating or dispenser application.

  Next, as shown in FIG. 1B, the orientation shape is transferred by pressing a mold having a concave portion of a desired shape against the ultraviolet curable resin 3 on the surface of the first transparent substrate 1. 12 and the seal barrier 5 are formed simultaneously. Details of a specific method of shape transfer will be described later. For the alignment film of the liquid crystal cell, a rubbing process (alignment process described in the prior art) of an alignment film material mainly composed of a polyimide resin or the like is generally used, but instead of this, in the case of the present invention, On the first transparent substrate 1, a means for aligning the liquid crystal was adopted by providing an alignment shape with directional unevenness of about several hundreds of nanometers in height.

  Next, as shown in FIG. 1 (c), a sealing material 6 made of an ultraviolet curable resin such as a radical type or a cation type in a closed ring pattern in which the outside of the seal barrier 5 is enclosed in a frame shape is applied to a screen. It is formed by a printing method. Note that, instead of this screen printing method, seal formation may be performed by dispenser application. However, in a small liquid crystal cell, the screen printing method is preferable because a large number of seal patterns can be formed at a time.

  Here, the height of the seal barrier 5 may be equal to or less than the height of the spacer mixed with the seal material, and may be equal to or less than the cell gap when the two transparent substrates are bonded together. It is essential.

  Next, as shown in FIG. 1 (d), a predetermined amount of liquid crystal 7 is dropped into the inner region of the seal barrier 5 by a dispenser. Subsequently, as shown in FIG. 1E, the first and second transparent substrates 1 and 8 face each other with their electrode formation surfaces facing each other. Here, an element having a desired cell thickness can be obtained by the action of the atmospheric pressure and the spacer contained in the sealing material 6 by releasing the atmosphere in a state of being bonded together after being accurately positioned in the vacuum chamber. .

Then, 3000 mj / cm ² of ultraviolet rays are irradiated to the joined cells after obtaining the desired cell thickness through the transparent substrate, and the sealing material 6 is completely cured, thereby completing the target liquid crystal cell. Here, when the curing is insufficient only by the ultraviolet irradiation, the sealing material 6 may be cured by performing a heat treatment at 120 ° C. for 1 hour.

  The liquid crystal cell shown in FIG. 1 (e) manufactured by the above process has a configuration in which a liquid crystal 7 is sandwiched between a first transparent substrate 1 and a second transparent substrate 8 via a ring-shaped sealing material 6. The seal barrier 5 is disposed on the inner wall surface of the seal material 6 in contact with the liquid crystal 7. The orientation shape 12 and the seal barrier 5 are formed of the same resin material by shape transfer using a mold.

  In the above description, the example in which the liquid crystal is dropped on the inner region of the sealing material 6 of the first transparent substrate 1 is shown. However, the liquid crystal is dropped on the central portion of the other second transparent substrate 8 to form a ring-shaped seal. A target liquid crystal cell may be formed by bonding to the first transparent substrate 1 on which the material 6 is formed.

  Next, a specific method for performing the orientation shape 12 and the seal barrier 5 by shape transfer as shown in FIG. 1B will be described. 2 (a) to 2 (c) are drawings showing in more detail the process of forming the orientation shape 12 and the seal barrier 5 shown in FIG. 1 (b).

  As shown in FIG. 2 (a), the upper surface of the ultraviolet curable resin 3 applied to the surface of the first transparent substrate 1 corresponds to the orientation shape and the seal barrier shape on the surface using quartz glass or metal as a material. The mold 4 in which the concave portion is formed is arranged to face each other. As the mold 4, a mold that has been subjected to a mold release process in advance by a method such as dipping or vapor deposition is used. For example, when a mold release process is performed on the surface of the mold 4, the mold 4 is dipped in a liquid release material and then slowly pulled up. Then, after drying, rinsing with a diluent for removing excess components on the surface, a monomolecular film of several nm can be formed on the concave surface of the mold 4.

  Next, as shown in FIG. 2B, the mold 4 is superposed with the first transparent substrate 1 being accurately aligned. Here, while observing the alignment marks formed at least at two places on the surface of the mold 4 and the alignment marks formed at least two places on the surface of the first transparent substrate 1 together with the transparent electrode pattern with a CCD camera. Alignment was performed so that the respective alignment marks overlapped. At this time, the excess ultraviolet curable resin 3 is removed by protruding from the edge between the mold 4 and the first transparent substrate 1.

Next, in a state where the mold 4 and the first transparent substrate 1 are superposed, the ultraviolet curable resin 3 is cured by uniformly irradiating ultraviolet rays at 3000 mj / cm ² through the first transparent substrate 1. Let Here, when only ultraviolet irradiation is insufficient, the sealing material may be cured by performing heat treatment at 120 ° C. for 1 hour.

  Next, as shown in FIG. 2C, the same resin is obtained by releasing the mold 4 from the first transparent substrate 1 on which the alignment shape 12 made of the ultraviolet curable resin 3 and the seal barrier 5 are formed. The production of the seal barrier 5 and the orientation shape 6 made of material is completed.

  As described so far, the liquid crystal cell manufacturing method of the present invention is compared with the conventional liquid crystal cell manufacturing process shown in FIG. 3 for forming a seal barrier in FIGS. Imprinting (embossing) includes two steps: a photolithography process using a photosensitive material, and a process from alignment film material printing to rubbing treatment for forming an alignment film in FIGS. 3C to 3D. As a result, the manufacturing process of the panel can be simplified and the manufacturing cost can be reduced.

  In addition, according to the manufacturing method of the present invention, the above-described process can be performed with a more simplified process and with a higher accuracy, and therefore, a high-quality liquid crystal cell can be manufactured as much as the process is simplified.

  In this embodiment, an ultraviolet curable resin is used to create a seal barrier and an alignment shape. However, in the process of FIG. 1A, the first transparent substrate 1 is formed using a thermosetting resin. A resin material may be applied to the surface. In that case, the orientation shape 12 and the seal barrier 5 can be cured by performing a heat treatment in accordance with the curing conditions of the resin material instead of the ultraviolet irradiation in the step shown in FIG. 1B (FIG. 2B). It ’s fine.

  Further, according to the manufacturing method of the present invention, the step of forming an alignment film composed of rubbing streaks applied by the rubbing cloth in the conventional process becomes unnecessary, and therefore liquid crystal contamination occurs due to the mixing of impurities from the rubbing cloth. The reliability of the liquid crystal cell can be expected to improve.

  Further, in this embodiment, the example in which the seal barrier 5 and the orientation shape 12 are simultaneously formed with the same mold 4 in the process of FIG. By forming in this way, the seal barrier 5, the orientation shape 12, and the electrode pattern formed on the transparent substrate are arranged in a target positional relationship. However, if there is a large difference between the height of the seal barrier (for example, 1 to 10 μm) and the height of the alignment shape (for example, 1 μm or less), or if the resin type or application method is changed, it is convenient for the panel specifications. For example, the seal barrier 5 and the orientation shape 12 may be formed by preparing separate molds.

  In the above description, the specific steps of the method of manufacturing a liquid crystal cell assuming a small liquid crystal optical element assuming an optical pickup are shown. However, the liquid crystal cell according to the present invention is originally a liquid crystal device including a liquid crystal display element. It can be applied in general.

It is process drawing which shows the manufacturing method of the liquid crystal cell of this invention. It is drawing which shows the sealing material formation process which concerns on this invention. It is drawing which shows the manufacturing method of the conventional liquid crystal cell. FIG. 4 is a diagram illustrating a process subsequent to FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st transparent substrate 2 Transparent electrode 3 UV curable resin 4 Mold 5 Seal barrier 6 Sealing material 7 Liquid crystal 8 Second transparent substrate 9 Alignment film 10 Photosensitive resin 11 Rotating roll 12 Alignment shape

Claims (3)

In the method of manufacturing a liquid crystal cell, a liquid crystal is sandwiched between a transparent substrate between one and the other through a ring-shaped sealing material, and a seal barrier is disposed on an inner wall surface of the seal in contact with the liquid crystal.
A resin material application step of applying a resin material to the surface of the one transparent substrate;
A shape transfer step of pressing a mold against the resin material to form a seal barrier together with the orientation shape;
A sealing material forming step of forming the sealing material in an outer region of the seal barrier;
A liquid crystal dropping step of dropping the liquid crystal on an inner region of the seal barrier in the one transparent substrate;
A substrate bonding step of bonding the other transparent substrate to the one transparent substrate via the sealing material. A method for manufacturing a liquid crystal cell, comprising: The method of manufacturing a liquid crystal cell according to claim 1, wherein the shape transfer step forms the alignment shape and the seal barrier simultaneously. In a liquid crystal cell in which a liquid crystal is sandwiched between one and the other transparent substrate via a ring-shaped sealing material, and a seal barrier is disposed on an inner wall surface of the seal in contact with the liquid crystal,
The liquid crystal cell, wherein the alignment shape and the seal barrier are formed of the same resin material by shape transfer using a mold.

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