JPH0451807B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method and apparatus for injecting liquid crystal into a liquid crystal cell constituting a liquid crystal display element. (Prior art) In recent years, demand for liquid crystal display elements has been increasing in various fields due to their thinness, lightness, and low power consumption. There is a strong demand for improvement. For this reason, various improvements have been made to methods and devices for injecting liquid crystal into liquid crystal cells, which greatly affect the reliability and manufacturing cost of liquid crystal display elements. As a conventional method and apparatus for injecting liquid crystal into this type of liquid crystal cell, there is a method employing an immersion injection method as shown in FIGS. 10 and 11, for example. In FIG. 10, 1 is a liquid crystal cell, and 2 is a liquid crystal container containing a liquid crystal 3. The liquid crystal cell 1 and the liquid crystal container 2 are placed in a vacuum chamber (not shown). Then, when the atmospheric pressure in the vacuum chamber, which is the atmospheric pressure of the liquid crystal cell 1, is reduced, the air inside the liquid crystal cell 1 is discharged through the injection hole 1a of the liquid crystal cell 1, and this liquid crystal cell 1 is shown by the imaginary line in the figure. When the pressure inside the vacuum chamber is increased to atmospheric pressure after being immersed in the liquid crystal 3,
Liquid crystal 3 in liquid crystal container 2 is injected into liquid crystal cell 1. FIG. 11 shows a case where an injection hole 4a is formed at the corner and liquid crystal 3 is injected into the liquid crystal cell 4.
In this case, in the liquid crystal cell 4, the liquid crystal 3 is located near the injection hole 4a.
immersed in. Also, JP-A-61-275726, JP-A-60-
Publication No. 41017 and Japanese Patent Application Laid-open No. 57-24914,
It is described that the liquid crystal is injected into the liquid crystal cell using a liquid crystal suction member etc. that impregnates the liquid crystal, and in these methods, the liquid crystal cell is injected by pressing the liquid crystal suction member etc. against the injection port and injecting the liquid crystal. This reduces the amount of unnecessary liquid crystal that adheres to the screen and reduces the number of cleaning steps. Furthermore, Japanese Patent Application Laid-Open No. 57-24915 and Utility Model Application No.
Japanese Patent No. 58-103021 describes a method in which a capillary tube is used as a liquid crystal introduction tube, and these devices also reduce waste of liquid crystal and improve productivity. (Problem to be Solved by the Invention) However, in the conventional method that adopts the immersion injection method, the liquid crystal cell 1 or the liquid crystal cell 4 is directly immersed in the liquid crystal 3 housed in the liquid crystal container 2, so that the liquid crystal 3 is injected into the liquid crystal cell. Not only is the liquid crystal 3 adhered widely to the liquid crystal cells 1 and 4, resulting in waste, but also the number of man-hours required to clean the liquid crystal cells 1 and 4 to which the liquid crystal 3 has adhered increases, increasing manufacturing costs. In addition, in the case of conventional methods using capillary tubes, liquid crystal suction members, etc., it is necessary to position the liquid crystal capillary tubes, liquid crystal suction members, etc. facing the injection port, making it difficult to inject liquid crystal into many liquid crystal cells at the same time. is difficult and requires improvement to increase productivity and reduce manufacturing costs. Specifically, when an injection hole is formed in a liquid crystal cell that opens not in an end surface but in a flat surface, for example, the injection hole 5 is formed in a liquid crystal cell 5 shown in FIG.
When trying to inject liquid crystal through the hole 5a, it is impossible to press a liquid crystal suction member or the like against the injection hole 5a opened in the flat surface, and even if a capillary tube is used, the above-mentioned difficulty becomes extremely significant. As described above, with the conventional method and apparatus for injecting liquid crystal into a liquid crystal cell, it has not been possible to improve productivity and reduce manufacturing costs. (Objective of the Invention) Therefore, the present invention reduces the adhesion of liquid crystal to liquid crystal cells, and makes it possible to simultaneously and easily inject liquid crystal into many liquid crystal cells, thereby improving the productivity of liquid crystal display elements and reducing manufacturing costs. The purpose is to reduce the (Structure of the Invention) In order to achieve the above objects, the method and device for injecting liquid crystal into a liquid crystal cell according to the present invention have the following features: (1) The atmosphere around the liquid crystal cell is reduced from atmospheric pressure to a predetermined pressure to The process includes discharging the air inside the cell through the injection hole, and inserting the liquid crystal cell near the injection hole into the upper part of the slit formed in the cell insertion tool in an atmosphere of a predetermined pressure. Soak it in the liquid crystal so that it is immersed in the liquid crystal,
A step of immersing the injection hole in the liquid crystal that is sucked up by capillary action within the slit, and a step of returning the atmosphere around the liquid crystal cell from a predetermined pressure to atmospheric pressure and injecting the liquid crystal into the liquid crystal cell through the injection hole immersed in the liquid crystal. and (2) a device for injecting liquid crystal into a liquid crystal cell through an injection hole formed in the liquid crystal cell, wherein a slit is formed into which the vicinity of the injection hole of the liquid crystal cell can be inserted into the upper part. a liquid crystal container capable of containing a liquid crystal and immersing the cell insertion tool in the liquid crystal so that the liquid crystal soaks the lower part of the slit; a depressurizing means capable of reducing the pressure and discharging the air inside the liquid crystal cell through the injection hole; The injection hole of the liquid crystal cell from which the air has been discharged is immersed in the liquid crystal above the slit. Embodiments of the present invention will be specifically described below with reference to the drawings. 1 to 6 are diagrams showing a first embodiment of an apparatus for injecting liquid crystal into a liquid crystal cell according to the present invention. First, the configuration of this device will be explained. In FIGS. 1 to 3, reference numeral 11 denotes a liquid crystal cell constituting a twisted nematic type (hereinafter referred to as TN type) liquid crystal display element. They are bonded together at the periphery with a sealant 13 at a predetermined interval so that their surfaces (not shown) face each other, and the thickness is 0.21 mm. Further, the liquid crystal cell 11 has an injection hole 11a formed in the plastic film substrate 12B, and is inserted into the liquid crystal container 14.
The accommodated liquid crystal L is injected into the interior through the injection hole 11a. Reference numeral 15 denotes a cell insertion tool made of, for example, a corrosion-resistant aluminum alloy, and a plurality of slits 16 are formed at a predetermined pitch in the cell insertion tool 15, extending perpendicularly to the longitudinal direction and having a groove width W larger than the thickness of the liquid crystal cell 11. This cell insertion tool 15 has a slit 16 for the liquid crystal L.
is fixed to the liquid crystal container 14 so that the lower part of each slit 16 is immersed, and the liquid crystal L that immerses the lower part of each slit 16 rises to a height H corresponding to the groove width W of the slit 16 due to capillary action.
Only the contents are sucked up. The relationship between the groove width W and the height H is for the liquid crystal L for Merck's TN type liquid crystal display element.
When measured using the ZL1 system, the values shown in the table below were obtained.

[Table] Also, as shown in FIG. 4, a plurality of liquid crystal cells 11 are arranged and held at equal intervals to the pitch between the slits 16 by cell holders 17, and the cell holders 17 are used to hold each liquid crystal cell 11. The vicinity of the injection hole 11a is positioned so as to face the slit 16 of the cell insertion tool 15, and the liquid crystal container 14 is fixed with a bolt (not shown) or the like.
is connected to. Specifically, the cell holder 17
In this case, the liquid crystal cell 11 is connected to the slit 16 by the groove 18a.
Cell guides 18L and 18R are guided on both the left and right sides so that the cell guides 18L and 18R can be inserted while keeping a predetermined gap between them, a pair of frames 19 (only one is shown) that connect the cell guides 18L and 18R at both ends, and a pair of brackets. A cell presser bar 22 is rotatably supported by the frame 19 at both ends via 21, and a stopper 23 whose both ends are fitted into a guide groove 19a formed in the frame 19 and movable along the groove 19a. It consists of a cell guide 18L,
A plurality of liquid crystal cells 11 supported by a stopper 23 guided by 18R can be simultaneously inserted into the slit 16 by moving the stopper 23. In order to facilitate insertion of the liquid crystal cell 11 into the slit 16, the cell insertion tool 15 is provided with a chamfer c at the entrance of the slit 16 (see FIG. 3). On the other hand, the liquid crystal cell 11, the liquid crystal container 14, the cell insertion tool 15, and the cell holder 17 are placed in a vacuum chamber (pressure reducing means) of a vacuum device (not shown), and this vacuum device uses air in the vacuum chamber, that is, The atmosphere around the liquid crystal cell 11 is reduced from atmospheric pressure to a predetermined pressure, and the air inside the liquid crystal cell 11 can be discharged to the outside through the injection hole 11a. The predetermined pressure here is a pressure value close to vacuum within a range in which the composition of the liquid crystal L does not change.
In addition, the vacuum device returns (increases the pressure) the atmosphere of the liquid crystal cell 11 from the predetermined pressure to atmospheric pressure by introducing nitrogen gas or the like into the vacuum chamber that has been reduced to a predetermined pressure.
be able to. Note that the groove width W of the slit 16 in this embodiment
is 0.3mm to 1.0mm for the thickness of liquid crystal cell 11, which is 0.21mm.
However, it is possible to implement the above-mentioned cell holder 17 with ease of manufacture, liquid crystal cell 11 and slit 1.
Comparing and considering the accuracy of the gap in 6, the groove width W is 0.6
Approximately mm is preferable. Further, the horizontal width X of the slit 16 in FIG.
If a is a round hole with a diameter of 1 mm, it is possible to set the horizontal width X to 2 mm or more, but in order to facilitate positioning in the horizontal width
degree is preferred. Furthermore, the liquid crystal cell 11 has an injection hole 11a that opens on the cell surface, and as shown in FIG.
The liquid crystal cells 26 and 27 shown in FIG. 2B may also be used. Next, an embodiment of the method of the present invention using the apparatus of the first embodiment described above will be described. Setting process First, a plurality of liquid crystal cells 11 are sequentially mounted on the cell holder 17 with the stopper 23 positioned at position S ₁ in FIG.
Hold down. That is, a plurality of liquid crystal cells 11 are set in the cell holder 17. On the other hand, slit 16
A predetermined amount of liquid crystal L is put into the liquid crystal container 14 so that the lower part of the liquid crystal L is immersed in the liquid crystal L. Degassing/holding step: Next, the vacuum device is used for the time shown in Figure 5.
The atmosphere around _the liquid crystal cell ₁₁ is reduced from atmospheric pressure P ₀ to a predetermined pressure P ₁ by reducing the pressure in the vacuum chamber from T 0 to T 1, and this is maintained from time T ₁ to T ₂ . The air inside the liquid crystal cell 11 is discharged (degassed) to the outside through the injection hole 11a. On the other hand, liquid crystal cell 11
After degassing, preferably a little before time T ₂ , the plurality of liquid crystal cells 11 are simultaneously lowered and inserted into the upper part of each slit 16 by moving the stopper 23 to position S ₂ in FIG. At this time, the injection hole 11a is immersed in the liquid crystal L because the liquid crystal L that has immersed the lower part of the slit 16 is drawn up to the upper part by capillary action. Injection/Holding Step Next, between time T ₂ and T ₃ , the atmosphere around the liquid crystal cell 11 is returned from the predetermined pressure P ₁ to atmospheric pressure P ₀ using the vacuum device, and the difference between the internal pressure and the external pressure of the liquid crystal cell 11 is reduced. Injection hole 1 immersed in liquid crystal L due to pressure
Liquid crystal L is injected into the liquid crystal cell 11 through 1a.
Then, the time until the liquid crystal L is completely injected (filled) into the liquid crystal cell 11, that is, from time _T3 to
Hold atmospheric pressure P ₀ until T ₄ . Sealing/Cleaning Process Next, the stopper 23 is returned to position S ₁ and a plurality of liquid crystal cells 11 are pulled out from the slit 16 at the same time, and the cell holder 17 is separated from the liquid crystal container 14 or the liquid crystal cell 11 is taken out from the cell holder 17. After that, the injection hole 11a is sealed with a sealant.
Next, the liquid crystal L adhering to the liquid crystal cell 11 is removed by cleaning or the like, but since the liquid crystal L is only a very small amount adhering to the vicinity of the injection hole 11a corresponding to the horizontal width X of the slit 16, Injection hole 11
Simply clean only the area near a. The liquid crystal L sucked up into the slit 16 in this way
If only the vicinity of the injection hole 11a of the liquid crystal cell 11 is immersed in the liquid crystal cell 11, the liquid crystal L can be easily injected into a large number of liquid crystal cells 11 even if the injection hole 11a opens on the cell surface. Also, the amount of liquid crystal L poured into the liquid crystal container 14 during one injection may be small. Furthermore, waste of the liquid crystal L can be reduced and the liquid crystal L can be removed by simple cleaning. Therefore, the liquid crystal L can be easily injected into a large number of liquid crystal cells 11 at the same time by simply matching the pitch of the slits 16 with the pitch of the arrangement of the liquid crystal cells 11 by the cell holder 17. Without,
It can be used with a variety of liquid crystal cells with different shapes, greatly improving productivity. Furthermore, a plurality of liquid crystal cells 11 attached to the cell holder 17 can be easily handled at the same time. 7 and 8 are diagrams showing a second embodiment of an apparatus for injecting liquid crystal into a liquid crystal cell according to the present invention. In FIGS. 7 and 8, 31 is a liquid crystal cell having an injection hole 31a opening on the cell surface, and the liquid crystal cell 31 includes, for example, a glass substrate 32A with a pair of electrodes,
32B are bonded together in substantially the same manner as the liquid crystal cell 11 of the first embodiment, and its thickness is 1.0 mm. 3
Reference numeral 3 denotes a cell insertion tool in which a plurality of slits 34 having a groove width of 1.6 mm are formed, and the cell insertion tool 33 is fixed in a liquid crystal container 35 that accommodates the liquid crystal L. The liquid crystal container 35 is supported by support means (not shown) so as to be rotatable within a predetermined angular range (for example, 90°) together with a cell holder (not shown) that is substantially similar to the cell holder 17 in the first embodiment. , by operating the support means, the liquid crystal cell 31, the cell inserter 33, and the liquid crystal container 35 are integrally assembled in FIG. 7a.
It can be rotated back and forth between the state shown in FIG. 7 and the state shown in FIG. 7b. That is, the liquid crystal container 35 can be rotated by a predetermined angle while containing the liquid crystal L.
Then, the slit 34 located above the liquid crystal level _H1 of the liquid crystal L in the state shown in FIG. 7a is lowered by the cell holder to the state shown in FIG.
The slit 34 is immersed in water and the liquid crystal cell 31 is inserted into the slit 34.
Internal gap (for example, 0.6 mm or less on the injection hole 31a side)
The liquid crystal L is sucked up by capillary action, and the injection hole 31a is immersed in the liquid crystal L.
Note that these liquid crystal cells 31, cell insertion tools 33,
The liquid crystal container 35, cell holder, support means, etc.
It is placed in a vacuum chamber similar to the first embodiment. To explain one embodiment of the method of the present invention using the device of the second embodiment, first, a plurality of liquid crystal cells 31 are set in the cell holder, while the liquid crystal container 35 is
A predetermined amount of liquid crystal L is put into the container. At this time, the liquid crystal cell 31 etc. are in the state shown in FIG. 7a. Next, the liquid crystal cell 31 is heated in a vacuum chamber in the same manner as in the first embodiment.
The atmosphere around the liquid crystal cell 31 is depressurized and maintained, and the air inside the liquid crystal cell 31 is discharged through the injection hole 31a, while the supporting means is operated to remove the liquid crystal cell 31, the cell inserter 33, the liquid crystal container 35, and the cell holder. Rotate them integrally to the state shown in FIG. 7b. At this time, the lower part of the slit 34 sinks below the liquid crystal surface H ₂ of the liquid crystal L in the liquid crystal container 35 and is immersed in the liquid crystal L, and as a result, the liquid crystal L is sucked up slightly above the liquid surface H ₂ within the slit 34. It will be done. Next, the vicinity of the injection hole 31a of the liquid crystal cell 31 is inserted into the slit 34 to a predetermined depth using the cell holder. At this time, the liquid crystal L is sucked up by capillary action into the narrow gap above the slit 34 into which the liquid crystal cell 31 is inserted, and the injection hole 31a is immersed in the liquid crystal L. Next, the atmosphere around the liquid crystal cell 31 is returned to atmospheric pressure, and the pressure difference between the inside and outside of the liquid crystal cell 31 causes the liquid crystal cell 31 to pass through the injection hole 31a immersed in the liquid crystal L.
Inject liquid crystal L into. In this way, the liquid crystal cell 31, cell insertion tool 33, liquid crystal container 35, etc. are rotated integrally to form the injection hole 3.
Even if the vicinity of 1a is immersed in the liquid crystal L, the liquid crystal L can be simultaneously and easily injected into a plurality of liquid crystal cells 31.
The same effects as in the first embodiment can be obtained. FIG. 9 is a diagram showing a third embodiment of an apparatus for injecting liquid crystal into a liquid crystal cell according to the present invention. In FIG. 9, 41 is a liquid crystal cell having an injection hole 41a, 42 is a cell insertion tool having a plurality of slits 43 into which the liquid crystal cell 41 can be inserted, and 44 is a liquid crystal storage on one longitudinal side of the cell insertion tool 42. Part 4
4a, and the cell insertion tool 42 is fixed to the liquid crystal container 44. In addition, the liquid crystal container 44 is attached to the cell insertion tool 4 together with a cell holder (not shown).
The liquid crystal container 44 can be rotated around a rotation axis perpendicular to the longitudinal direction of the liquid crystal container 44, and the liquid crystal L in the liquid crystal container 44 is moved to a liquid level _H3 or _H4 by the rotation of the liquid crystal container 44. Lower the bottom of the slit 43 to the liquid level H ₄
It can be immersed in liquid crystal L. To explain one embodiment of the method of the present invention using the device of the third embodiment, first, a predetermined amount of liquid crystal L is put into the liquid crystal container 44, and the longitudinal direction of the cell insertion tool 42 is set vertically. After setting the liquid level of L to the liquid level _H3 (the state shown in Figure 9), remove the liquid crystal cell 4.
1. The atmosphere around the liquid crystal cell 41 is reduced from atmospheric pressure to a predetermined pressure and maintained in a vacuum chamber containing the cell insertion tool 42, liquid crystal container 44, etc., and the air inside the liquid crystal cell 41 is degassed. . When the inside of the liquid crystal cell 41 is degassed, the liquid crystal cell 41, the cell inserter 42, the liquid crystal container 44, etc. are rotated so that the liquid level of the liquid crystal L becomes the liquid level _H4 , and then (also at the same time) the cell is held. The injection holes 41a of a plurality of liquid crystal cells 41 are
The lower part of the slit 43 is immersed in the liquid crystal L by simultaneously inserting the neighboring parts into each slit 43. At this time, the injection hole 41a of the degassed liquid crystal cell 41 is immersed in the liquid crystal L sucked up to the upper part of the slit 43 by capillary action. Next, the atmosphere around the liquid crystal cell 41 is returned to atmospheric pressure, and the liquid crystal L is injected into the liquid crystal cell 41 due to the differential pressure between the inside and outside of the liquid crystal cell 41. Even in this case, the same effects as in the first and second embodiments can be obtained. In the devices of the first to third embodiments, the liquid crystal cells 11, 31, 41 are lowered to the liquid surface side of the liquid crystal L using the cell holder 17 or the like, and the slits 16, 3
4 and 43, but the liquid crystal container and the cell insertion tool may be raised toward the cell holder that holds the liquid crystal cell in a fixed position, and both may be moved up and down to cause relative displacement. Good too. Also,
After the liquid crystal L is sucked up into the slits 16, 34, 43, the liquid crystal cells 11, 31, 41 are sucked up into the slit 1.
Instead of inserting the liquid crystal L into the upper part of the liquid crystals 6, 34, and 43, it is also possible to encourage the liquid crystal L to be sucked up by capillary action after this insertion operation. Furthermore, the liquid crystal containers 14, 3
If the shape of 5 and 44 is made such that the liquid surface when the liquid crystal L is injected is wide and the bottom area is small at the same time, the degassing of the liquid crystal L is promoted well and the liquid surface during the liquid crystal injection is reduced. This is preferable because the decrease is also small. (Effects) According to the present invention, the atmosphere around the liquid crystal cell is depressurized and maintained to exhaust the air inside the liquid crystal cell, and in this atmosphere, air is sucked up from the liquid surface by capillary action within the slit of the cell insertion tool. Since only the liquid crystal near the injection hole of the liquid crystal cell is immersed in the liquid crystal, it is possible to minimize the amount of liquid crystal that adheres to the liquid crystal cell when liquid crystal is injected, and it is also possible to Liquid crystal can be easily injected into two liquid crystal cells at the same time. As a result, productivity of liquid crystal display elements can be significantly improved and manufacturing costs can be reduced.

[Brief explanation of the drawing]

1 to 6 are diagrams showing a first embodiment of the device of the present invention, FIGS. 1a and 1b are configuration diagrams of the main parts thereof, FIG. 2 is a plan sectional view of the main parts of the liquid crystal cell, and FIG. Figure 3a
is a side sectional view of the cell insertion tool and liquid crystal container,
Figure 3b is a sectional view taken along line BB in Figure 3a, Figure 4a,
Fig. 5 is a time chart for explaining an embodiment of the method of the present invention using the device of the first embodiment, Fig. 6 a, b 7 and 8 are views showing a second embodiment of the device of the present invention, and FIGS.
8 is a perspective view of the main part, and FIG. 9 is a perspective view of the main part showing a third embodiment of the apparatus of the present invention. Figures 10 to 12 are diagrams showing conventional examples, Figures 10 and 11 are schematic configuration diagrams of devices that implement the conventional immersion injection method, respectively, and Figure 12 is a diagram for explaining the problems of another conventional example. FIG. 2 is a plan view of a liquid crystal cell. 11, 31, 41...Liquid crystal cell, 11a, 31
a, 41a... Injection hole, 14, 35, 44... Liquid crystal container, 15, 33, 42... Cell insertion tool, 1
6, 34, 43...slit, L...liquid crystal.

Claims (1)

[Claims] 1. A step in which the atmosphere around the liquid crystal cell is reduced from atmospheric pressure to a predetermined pressure and the air inside the liquid crystal cell is discharged through the injection hole; Inserting the cell into the upper part of the slit formed in the cell insertion tool, immersing the cell insertion into the liquid crystal so that the lower part of the slit is immersed in the liquid crystal, and immersing the injection hole in the liquid crystal sucked up by capillary action within the slit; A method for injecting liquid crystal into a liquid crystal cell, comprising the steps of: returning the atmosphere around the cell from a predetermined pressure to atmospheric pressure; and injecting liquid crystal into the liquid crystal cell through an injection hole immersed in liquid crystal. 2 A device for injecting liquid crystal into a liquid crystal cell through an injection hole formed in the liquid crystal cell, which comprises a cell inserter having a slit formed in the upper part thereof into which the vicinity of the injection hole of the liquid crystal cell can be inserted, and a liquid crystal inside. A liquid crystal container that can accommodate the liquid crystal and into which a cell insertion tool can be immersed into the liquid crystal so that the liquid crystal immerses the lower part of the slit, and an injection hole that reduces the atmosphere around the liquid crystal cell from atmospheric pressure to a predetermined pressure and injects air inside the liquid crystal cell. and a depressurizing means capable of discharging the liquid crystal through the slit of the cell insertion tool immersed in the liquid crystal container, the liquid crystal is sucked up by capillary action within the slit of the cell insertion tool immersed in the liquid crystal container, and the air inside is discharged by the depressurizing means. A device for injecting liquid crystal into a liquid crystal cell, which is characterized by immersing liquid crystal into the liquid crystal at the top of a slit.