JP2008129327A - Method for manufacturing liquid crystal element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of failure in long-term reliability when a liquid crystal element having a level difference around an injection hole is sealed by a sealing material. <P>SOLUTION: A method for manufacturing a liquid crystal display element includes a step of applying a first sealing material 18 on an injection hole and a step of applying a second sealing material 19 to cover the first sealing material 18. Thereby, a portion with weak adhesion strength on the interface between the sealing material and a substrate seal material and an insufficient portion of the sealing material generating upon pouring the sealing material to the injection hole are reinforced by the second sealing material 19. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal element sealing device for sealing an injection hole for a liquid crystal element that injects liquid crystal from a seal opening (hereinafter referred to as an injection hole) into a space formed by two substrates and a seal. Involved in the process.

  Liquid crystal elements for controlling light transmission have been put into practical use as various display bodies ranging from mobile phones to large-sized liquid crystal televisions. Recently, they have also been used as aberration correction elements in optical disk drive devices. In such a liquid crystal element, liquid crystal is sandwiched between two transparent substrates facing each other with a gap of about several micrometers, and the periphery of the transparent substrate is sealed with a seal. A widely used method for sandwiching liquid crystal (hereinafter referred to as a vacuum injection method) is that two transparent substrates are pasted together in advance through a seal, and then the space formed by the transparent substrate and the seal is evacuated, An injection hole provided in advance is immersed in the liquid crystal reservoir, the outside is returned to the external pressure, and the liquid crystal is injected using the pressure difference between the outside and this space. In this vacuum injection method, the injection hole is finally sealed with an adhesive.

  The application situation of the injection hole and the sealing material will be described with reference to FIG. 6A and 6B are a perspective view and a plan view of the liquid crystal element when the substrate end surfaces on the injection hole side are aligned vertically, and FIGS. 6C and 6D are the substrates on the injection hole side. FIG. 6 is a perspective view and a plan view of a liquid crystal element in which end faces are not aligned and a step is formed around an injection hole.

  The structure in which the substrate end face on the injection hole side is aligned has a short process and has high efficiency of using liquid crystal at the time of injection. 6 (a) and 6 (b), the upper substrate 60 and the lower substrate 61 have the same substrate end surface where the injection holes formed in the seal 62 are present, while the upper substrate 60 is opposite to the substrate end surface. On the other hand, the lower substrate 61 extends. A connection electrode for transmitting a drive signal from an external circuit to the drive electrode of the liquid crystal element formed in the planar region surrounded by the seal 62 is provided in the extending portion (not shown). The sealing material 63 is applied so as to close the injection hole and rises from the end face, and a part of the sealing material penetrates into the injection hole. The injection hole has a seal projection 64 bent at a right angle to the outside with respect to the seal side. The seal protrusion 64 prevents air from entering after sealing and leakage of liquid crystal. The seal 62 is slightly inside the outer periphery of the upper substrate 60 and linearly surrounds the gap between the upper substrate 60 and the lower substrate 61. However, since the seal 62 is seen through the upper substrate 60, it is indicated by a dotted line. The seal 62 has an opening on the lower side of FIG. 6B, which serves as a liquid crystal injection hole. (The same applies hereinafter)

  A step may be formed on the injection hole side for various reasons, such as when it is desired to provide a connection electrode also on the injection hole side or when an end surface on the injection hole side is used as a reference surface. 6 (c) and 6 (d), the lower substrate 66 also has an extended portion of the lower substrate 66 on the injection hole side, and an injection hole is formed at an end surface of the upper substrate 65 and a corner formed from the extended portion. Exists. Similar to (a), there is an extended portion of the lower substrate 66 on the side facing the injection hole. The sealing material 68 is applied so as to close the injection hole, swells at the extending portion, and a part of the sealing material enters the injection hole. In consideration of the cutting accuracy of the upper substrate 65, a part of the sealing projection 69 of the injection hole protrudes from the extended portion of the lower substrate 66. The end surface of the lower substrate 66 on the injection hole side can be used as a reference surface if it is processed with high accuracy because no sealing material is attached.

In the liquid crystal element having a step in the injection hole portion shown in FIGS. 6C and 6D, the liquid crystal may be injected before the step is formed, or the liquid crystal may be injected after the step is formed. For example, in Reference 1, “in a liquid crystal display element in which the end surfaces on the liquid crystal injection hole side of two substrates on which electrodes are formed are not aligned, a sealing material for bonding the two substrates is used as an injection hole for liquid crystal injection. This part is made long and extended to the end of the substrate, liquid crystal is injected between the two substrates, one of the substrates is then cut at a predetermined position, and the liquid crystal injection hole side of the two substrates is The shape of the end faces is not uniform (step), and finally the liquid crystal material injection hole is sealed. " Reference 1 was intended to reduce the consumption of liquid crystal during injection by creating a wall with a sealing material.

If the sealing condition is bad, the liquid crystal may leak through the injection hole or foreign matter may enter from the outside. For example, in Reference 2, “an alignment film is also provided in the injection hole and liquid crystal is in contact with the surface active material on the substrate at the time of liquid crystal injection, while avoiding the problem that the hygroscopic alignment film is not exposed. The protruding alignment film is covered with a sealing material, and the sealing material adheres to the substrate surface to ensure sufficient adhesion, thereby preventing moisture from entering. "
Japanese Patent No. 2776028 Japanese Patent No. 3229172

  When a liquid crystal element having a step around the injection hole was sealed with a sealing material, the electrical resistance was lowered due to the ingress of moisture, and the liquid crystal leaked out. Since Document 1 is aimed at reducing the consumption of liquid crystal during injection, it does not mention the above-mentioned matters relating to long-term reliability. In addition, this time, the alignment film was formed on the substrate region specified by the printing method was similar to the situation in Reference 2, but there was no alignment film near the injection hole, so the method shown in Reference 2 This bug cannot be solved.

  Accordingly, an object of the present invention is to provide a method of manufacturing a liquid crystal element that can ensure long-term reliability around an injection hole.

  In a method for manufacturing a liquid crystal element having an injection hole for injecting liquid crystal into a space formed by enclosing a pair of opposing substrates with a sealing material, a step of injecting liquid crystal, and a first sealing material in the injection hole And a step of further applying a second sealing material so as to cover the first sealing material.

  The method further includes a step of removing the first sealing material outside the injection hole.

  The method further includes the step of forming the extension, and the injection hole is formed in the extension.

  The first sealing material is applied so as to remain on the extended portion.

  It has the process of wash | cleaning the peripheral part of an injection hole between the process of apply | coating a 1st sealing material, and the process of apply | coating the said 2nd sealing material.

  The extending portion is characterized in that an electrode for connecting to an external circuit is not formed.

A sufficient long-term reliability could not be ensured only by applying the first sealing material around the injection hole. This is a combination of the following two causes. The first cause is that the adhesion force between the sealing material and the sealing material is weaker than the adhesion force between the sealing material and the substrate surface, so that moisture enters and liquid crystal leaks out at the interface between the sealing material and the sealing material. It is what has been. The second cause is that the sealing material flows into the injection hole at the time of sealing, so that the flow rate of the sealing material that wraps around the seal projection or the tip thereof is faster than the flow rate of the sealing material that flows near the center of the injection hole. Therefore, a portion with little sealing material (peeling off) is formed around the seal projection. When the second sealing material is applied so as to cover the first sealing material that has insufficient long-term reliability because it is bonded to the seal protrusion, the second sealing material is the first sealing material. Long-term reliability can be ensured because it can be bonded with strong adhesion only to the surface and substrate surface. Further, unlike the first sealing material, the second sealing material does not flow toward the injection hole after being applied, and therefore, there is no portion with a small sealing material between the sealing protrusion and the second sealing material. For this reason, even if the seal protrusion happens to protrude from the first sealing material, it is covered with the second sealing material, so long-term reliability is not impaired.

If the first sealing material remaining outside the injection hole is removed before the second sealing material is applied, the first sealing material remains only in the injection hole. For this reason, the first sealing material around the seal projection portion, which has a particularly weak adhesion, is removed, and the second sealing material is in close contact with the substrate surface while covering the first sealing material remaining in the injection hole. Long-term reliability is further improved due to adhesion by force.

As described in the background art, when the extension part is formed and the injection hole is provided in the extension part, the design of the liquid crystal element when the number of connection terminals is large or when the extension part is used as a reference side is designed. The degree of freedom increases. However, in this case, since the cutting projection and the seal printing accuracy of the substrate are taken into consideration, the seal protrusion is designed to protrude from the extended portion, so that the cause of the failure that occurs at the interface between the sealing material and the seal material extends to the extended portion. . After the first sealing material has entered the injection hole, the first sealing material is applied so that the first sealing material remains on the extending portion, and the first sealing material is covered. If the second sealing material is applied, long-term reliability can be ensured for the reasons described above. Further, if the first sealing material remaining outside the injection hole is removed, the long-term reliability is further improved.

  If the peripheral portion of the injection hole is washed before the second sealing material is applied after the first sealing material is applied, the liquid crystal remaining around the injection hole and on the substrate surface can be completely removed. Since the second sealing material and the substrate surface can be reliably adhered, the long-term reliability is further improved.

  Stress in the vicinity of the interface due to thermal expansion, etc. because there is no electrode for connecting to the external circuit at the extension part where the injection hole is provided, and there is no adhesion part with the connection electrode with different adhesion force Long-term reliability is improved because of the more uniform distribution.

Since the method for manufacturing a liquid crystal element of the present invention has the above-described configuration and operation, the infiltration of foreign matter due to weak adhesion or peeling between the sealing material and the sealing material and the liquid crystal material Long-term reliability can be secured because it can cope with leakage.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Example 1)
The first embodiment shown in FIGS. 1 and 2 includes a step of forming an extending portion, a step of applying a first sealing material to the injection hole, a step of cleaning the peripheral portion of the injection hole, A step of applying the second sealing material so as to cover the sealing material. FIG. 1 is a process diagram from a mother substrate that has been overlaid to the application of a second sealing material, and FIG. 2 shows the sealing protrusion of the injection hole after the second sealing material is cured. It is sectional drawing which carries out a longitudinal section.

FIG. 1A shows a state in which the two mother substrates 10 that are overlapped are bonded together by a sealing material 11. Opposing surfaces of the mother substrate 10 have a certain gap due to spacers, and electrodes of individual liquid crystal elements are formed in regions corresponding to the sealing material 11. Although the sealing material 11 is arranged in a matrix of 4 rows and 4 columns on the mother substrate 10, several hundreds of actual aberration correcting liquid crystal elements are arranged on the mother substrate. The sealing material 11 is printed on one of the two mother substrates 10, and after the two mother substrates 10 are overlaid, they are baked and cured in a pressurized state.

  FIG. 1B shows a series of steps including a step of cutting out liquid crystal element groups (hereinafter referred to as strips) arranged in a horizontal row from the mother substrate 10. This process is as follows. A scratch (hereinafter referred to as a scribe line) is applied to the mother substrate 10 and pressure is applied to the scribe line to divide the mother substrate 10 and cut out strips 12.

  FIG. 1 (c) shows a series of steps including a step of forming the extending portion in the strip 12. This process is as follows. When a scribe line is inserted into the upper substrate 15, only the upper substrate 15 is split, and unnecessary portions are removed, the lower substrate 13 appears, and the extension portion 14 on the injection hole side and the extension portion 16 on the opposite side of the injection hole are formed. The

  FIG. 1D shows a series of steps including a step of injecting the liquid crystal 17 into each element region on the strip 12. This process is as follows. The strip 12 and the liquid crystal reservoir are placed in a vacuum chamber, and the inside of the chamber is evacuated. When the injection hole of the strip 12 is immersed in the liquid crystal reservoir and the inside of the chamber is returned to the atmospheric pressure, the liquid crystal 17 enters the space formed by the upper and lower substrates 15 and 13 and the sealing material 11.

  FIG. 1 (e) shows a series of steps including a step of applying the first sealing material 18 to the injection hole of each element region on the strip 12. This process is as follows. The strip 12 into which the liquid crystal 17 has been injected is taken out of the vacuum chamber, the liquid crystal adhering to the extension 14 is wiped off, and the first sealing material 18 is applied to each injection hole with a dispenser.

  FIG. 1 (f) shows a series of steps including a step of allowing the first sealing material 18 to enter the injection hole and then hardening. This process is as follows. The space filled with the liquid crystal 17 is cooled, the liquid crystal 17 is contracted, and the sealing material 18 is drawn into the injection hole. In the figure, 18a is a sealing material that has entered the injection hole. The first sealing materials 18 and 18a are cured by irradiating with ultraviolet rays.

  FIG. 1G shows a series of steps including a step of applying a second sealing material 19 so as to cover the first sealing material 18 for each element on the strip 12. . This process is as follows. After the first sealing material 18 is cured, the end surface of the extended portion 14 and the upper substrate 15 on the injection hole side is cleaned (the cleaning process is not shown), and the liquid crystal and other foreign matters adhering thereto are removed. Remove. Thereafter, a second sealing material 19 is applied by a dispenser so as to completely cover the first sealing material 18 and the seal protrusion of each liquid crystal element, and the sealing material 19 is cured by ultraviolet rays.

  When the reference surface is formed, a part of the extending portion 14 is cut off with high accuracy by dicing at a right angle to the extending direction. Finally, a scribe line is inserted into the strip 12 to separate each liquid crystal element.

  The state of the injection hole of the liquid crystal element will be described with reference to FIG. In addition, FIG. 1 and FIG. 2 show the same member with the same number. A liquid crystal 17 is filled in a 6 μm gap between the upper substrate 15 and the lower substrate 13. The sealing protrusion 11a of the sealing material protrudes from the upper substrate 15 to the extending portion by about 100 to 200 μm. The first sealing material 18 is bonded to the upper surface of the seal projection and the end surface of the upper substrate 15. Since the first sealing material 18 cannot necessarily guarantee that the seal protrusion 11a is covered with the flow when drawn into the injection hole after application, a part of the seal protrusion 11a is assumed to be in the first state assuming a bad situation. It is shown so as to be exposed from the sealing material 18. The second sealing material 19 completely covers the exposed portion of the first sealing material 18 and the seal projection 11 a and adheres to the end surface of the upper substrate 15 and the substrate surface of the extension portion of the lower substrate 13. .

(Example 2)
The second embodiment shown in FIGS. 3 and 4 is obtained by adding a step of removing the first sealing material outside the injection hole to the first embodiment. FIG. 3 is a process diagram from the mother substrate that has been overlapped to the second sealing hole, and FIG. 4 is a cross-sectional view that longitudinally cuts around the injection hole after the second sealing. 3, 4 and FIGS. 1 and 2 are denoted by the same reference numerals with respect to the same members as in the first embodiment. Also, the steps from (a) to (e) of FIG. 3 are the same as the steps from (a) to (e) of the first embodiment shown in FIG.

  FIG. 3 (f) shows a series of steps including a step of removing the sealing material and the sealing material remaining in the extending portion after the first sealing material 18 is infiltrated into the injection hole and cured. ing. This process is as follows. Similarly to Example 1, the space filled with the liquid crystal 17 is cooled, the liquid crystal 17 is contracted, the first sealing material 18 is drawn into the injection hole, and the first sealing materials 18 and 18a are irradiated with ultraviolet rays and cured. Let Thereafter, the first sealing material 18 remaining in the extending portion 14 is scraped off together with the seal protrusion with a knife.

    FIG. 3G shows a series of steps including a step of further applying a second sealing material 19 so as to cover the first sealing material 18 for each element on the strip 12. . This process is as follows. After the seal protrusion and the first sealing material 18 remaining on the extension part 14 are removed, the end face of the extension part 14 and the upper substrate 15 on the injection hole side is cleaned (the cleaning process is not shown), The liquid crystal, sealing material, and other foreign matters adhering thereto are removed. Thereafter, the second sealing material 19 is applied to the end surface of the first sealing material 18a in the injection hole of each liquid crystal element and the substrate surface around the injection hole with a dispenser, and the sealing material 19 is cured by ultraviolet rays.

  The state of the injection hole of the liquid crystal element will be described with reference to FIG. (A) is sectional drawing which longitudinally cuts a seal projection part, (b) is sectional drawing which longitudinally cuts the center of an injection hole. In (a), the 6 μm gap between the upper substrate 15 and the lower substrate 13 is sandwiched between the liquid crystal 17 and the seal protrusion 11b of the seal material left uncut. The seal material of the seal protrusion is removed from the extended portion of the lower substrate 13, the end surface of the seal protrusion 11 b where the second sealing material 19 remains, the end surface of the upper substrate 15, and the extension of the lower substrate 13. It adheres to the board surface of the part. In (b), between the upper substrate 15 and the lower substrate 13, the liquid crystal 17 and the sealing material 18 that has entered the injection hole are sandwiched, and the second sealing material 19 is placed in the injection hole in the extended portion. The end surfaces of the seal projections 18 a remaining on the end surface of the upper substrate 15 and the upper substrate 15 of the extended portion of the lower substrate 13 are bonded.

  When the reference surface is formed, a part of the extending portion 14 is cut off by dicing at a right angle to the extending direction as in the first embodiment. The first embodiment is an effective method when a relatively large extending portion 14 is provided, but the second embodiment is effective when the extending portion 14 must be narrowed. In the second embodiment, even if a part of the second sealing material 19 is cut off at the time of dicing, the long-term reliability is not deteriorated because the seal protrusion does not exist in the extending portion 14. Finally, a scribe line is inserted into the strip 12 to separate each liquid crystal element.

(Example 3)
In Example 3 shown in FIG. 5, the process of removing the first sealing material outside the injection hole of Example 2 is changed to dicing. FIG. 5 is a cross-sectional view of the injection hole sealing protrusion, which shows a process from curing the first sealing material to creating a reference surface. In addition, the same member as Example 1 and Example 2 is shown with the same number as FIG. 1, FIG. 5 (e), (f), and (g) correspond to (e), (f), and (g) in FIG. 3, and FIG. 5 (h) includes a reference surface creation step. A series of steps is shown.

FIG. 5E shows a state in which the first sealing material 18 has been cured in a series of steps including the step of applying the first sealing material 18. A liquid crystal 17 is filled in a 6 μm gap between the upper substrate 15 and the lower substrate 13. The seal protrusion 11a made of the seal material protrudes from the upper substrate 15 to the extended portion by about 100 to 200 μm. The first sealing material 18 is bonded to the upper surface of the seal projection 11 a and the end surface of the upper substrate 15. Since the first sealing material 18 cannot necessarily guarantee that the seal protrusion 11a is covered with the flow when drawn into the injection hole after application, a part of the seal protrusion 11a is assumed to be in the first state assuming a bad situation. It is shown so as to be exposed from the sealing material 18.

  FIG. 5F shows a situation where the first sealing material 18 is removed by dicing in a series of steps including the step of removing the first sealing material 18 outside the sealing hole. This process is as follows. After the first sealing material 18 is dipped into the injection hole and hardened, the end surface 21 of the upper substrate 15 and the upper surface 22 of the extended portion are each cut by 75 μm with a dicing blade to form a rough surface. Since the thickness of the dicing blade is 150 microns, a plurality of grooves (notches of 75 microns) are made at right angles to the extending direction of the extending portion 14 (perpendicular to the paper surface). At this time, the first sealing material 18 and the seal protrusion 11a remaining in the extending portion, and the first sealing material 18a (not shown) and a part of the seal protrusion 11a in the injection hole are also included. Scraped off. Although not shown, the first sealing material 18a remains in the injection hole (position overlapping the seal projection 11a).

  FIG. 5G shows a situation where the second sealing material 19 is cured in a series of steps including a step of applying the second sealing material 19 so as to cover the first sealing material 18. Is shown. The second sealing material 19 is bonded to the end surface of the seal projection 11a, the end surface 21 of the upper substrate 15, and the upper surface 22 of the extending portion. Although not shown, the second sealing material 19 is also bonded to the end surface of the first sealing material 18a remaining in the injection hole.

  FIG. 5H shows a situation where the reference surface 23 has been created in a series of steps including the reference surface creation step. A part of the extended portion 14 is cut off by dicing at a right angle to the extending direction to create a reference surface 23. As a result, the width of the extended portion is 0.5 mm, and a part of the second sealing material 19 is also cut during dicing. Finally, a scribe line is inserted into the strip 12 to separate each liquid crystal element.

  The first sealing material 18 and the second sealing material 19 may be the same material or different materials. Since the second sealing material 19 hardly touches the liquid crystal, there is no need to consider the compatibility with the liquid crystal, so the options are widened.

In each of the first, second, and third embodiments, the liquid crystal 17 was injected after the extended portion 14 was formed. However, the extended portion may be formed after the liquid crystal is injected. In this case, the seal projection of the injection hole is extended to the end of the extension side substrate, liquid crystal is injected from between the seal projections, and then the extension is formed to perform the first sealing. Since the seal protrusion remains in the extended portion, it is preferable to apply the second sealant after removing the sealant and the seal material of the seal protrusion.

It is process drawing of the liquid crystal element of Example 1 of this invention. It is sectional drawing which longitudinally cuts the sealing projection part of the sealing material of the liquid crystal element of Example 1 of this invention. It is process drawing of the liquid crystal element of Example 2 of this invention. It is sectional drawing which carries out the longitudinal section around the injection hole of the liquid crystal element of Example 2 of this invention. It is sectional drawing for every process around the injection hole of the liquid crystal element of Example 3 of this invention. It is the perspective view and top view which looked at the liquid crystal element of the prior art example from the injection hole side.

Explanation of symbols

10 Mother substrate 11, 62, 67 Sealing material 13, 61, 66 Lower substrate 14, 16 Extension portion 15, 60, 65 Upper substrate 17 Liquid crystal 18 First sealing material 19 Second sealing material 21 Upper substrate 21 End surface 22 Upper surface 23 of extension part Reference surface 63, 68 Sealing material 64, 69 Seal projection part of injection hole

Claims (6)

In a method of manufacturing a liquid crystal element having an injection hole for injecting liquid crystal into a space formed by enclosing a pair of opposing substrates with a sealing material,
Injecting the liquid crystal;
Applying a first sealing material to the injection hole;
Applying a second sealing material to cover the first sealing material;
A method for producing a liquid crystal element, comprising: The method of manufacturing a liquid crystal element according to claim 1, further comprising a step of removing the first sealing material outside the injection hole.   The method for manufacturing a liquid crystal element according to claim 1, further comprising a step of forming an extension portion, wherein the injection hole is formed in the extension portion.   The method for manufacturing a liquid crystal element according to claim 3, wherein the first sealing material is applied so as to remain on the extending portion.   5. The method according to claim 1, further comprising a step of cleaning a peripheral portion of the injection hole between the step of applying the first sealing material and the step of applying the second sealing material. The manufacturing method of the liquid crystal element of any one. 6. The method of manufacturing a liquid crystal element according to claim 3, wherein an electrode for connecting to an external circuit is not formed in the extension portion.

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