JP3599604B2 - Liquid crystal panel manufacturing method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a liquid crystal panel in which liquid crystal is injected into a liquid crystal panel, and a liquid crystal injection port is sealed with a sealing resin.
[0002]
[Prior art]
In recent years, the display quality of liquid crystal panels has been increasing day by day, and has progressed from use only for character recognition to quality that can withstand full-color image display. Furthermore, coupled with the improvement in productivity of large LCD panels, LCD panels have finally entered the monitor market, which was the dominant market for CRTs.
[0003]
In order for a liquid crystal monitor to surpass a CRT in this market, a larger screen and higher quality display are required for the liquid crystal panel.
In order to obtain high display quality, production processes such as improvement of performance such as bright, wide viewing angle and high resolution, uniform display over the entire screen, and uniform performance between liquid crystal panels It is important to work on both sides, such as improving the quality of products. Among them, the most important thing in production for realizing uniform display over the entire screen is formation of a uniform gap between substrates of a liquid crystal panel.
[0004]
By the way, a general method of manufacturing such a liquid crystal panel is based on the following procedure.
FIG. 6 shows a conventional liquid crystal panel.
The panel 1 is configured by bonding a pair of substrates with a sealing resin 2 and interposing a liquid crystal between the two substrates.
[0005]
Specifically, first, in order to bond the two substrates subjected to the orientation treatment with a predetermined gap, the sealing resin 2 is applied linearly to one of the substrates so as to surround the outer peripheral portion of the display area. At this time, a part without the sealing resin 2 is provided in a part so that liquid crystal can be injected between the two substrates after the substrates are bonded to each other, and liquid crystal injection ports 3a and 3b are formed. Further, a certain amount of spacer having a predetermined particle size is mixed in the sealing resin 2 so that a gap is formed between the two substrates.
[0006]
Next, a spacer having a predetermined particle size is sprayed on one side of the substrate.
This spacer is also for providing a gap between the substrates, and the spacer mixed in the sealing resin holds the gap at the outer edge of the display area, whereas this spacer covers the entire display area within a predetermined area. It is important to keep in the gap.
[0007]
The other substrate is bonded to the substrate having undergone such a process, and the sealing resin is cured to form the panel 1. In this state, air enters the gap between the substrates and is connected to the outside through the inlet, so that the pressure inside and outside the panel is 1 atm (101300 Pa).
When injecting liquid crystal into the panel 1, a vacuum injection method is generally performed. The vacuum injection method is a method in which air in a panel is evacuated by evacuation, and then a liquid crystal material is injected using a capillary phenomenon and a pressure difference between the inside and outside of the panel.
[0008]
Usually, first, the container containing the panel 1 and the liquid crystal material is put into an injection device, and the inside of the injection device is evacuated to 1 Pa or less. At this time, the panel 1 and the liquid crystal material are not in contact with each other, and the air in the panel 1 is exhausted from the injection ports 3a and 3b, and the pressure becomes 1 Pa or less, which is the same as in the apparatus.
Next, the injection ports 3a and 3b are brought into contact with the liquid crystal material, and nitrogen is introduced into the injection apparatus to increase the pressure in the apparatus to 1 atm. In this state, a pressure difference of approximately 1 atm is generated inside and outside the panel, and the liquid crystal material is injected into the panel by this force.
[0009]
The pressure difference between the inside and outside of the panel becomes small until the moment when the entire inside of the panel 1 is filled with the liquid crystal material. If left as it is, the liquid crystal continues to be injected until the pressure difference between the inside and outside of the panel disappears.
The gap between the liquid crystal panels formed by the pressure difference between the inside and the outside differs. That is, the gap is thinner as the external pressure is higher, and thicker as the external pressure is lower.
[0010]
Usually, in this liquid crystal injection step, it takes time to evacuate or inject, so that many panels are put in one large injection device and injection is performed. At this time, the amount of spacers and the size of the injection port There are subtle differences in the time that the injection port contacts the liquid crystal material, and the liquid crystal is not injected at exactly the same speed.
Therefore, the time of the injection step is set to be long so that all the panels can be injected surely. However, the pressure difference between the inside and outside of each panel varies, and a uniform gap cannot be formed by this step alone.
[0011]
Therefore, generally, after this liquid crystal injection step, a step of pressing the liquid crystal panel is performed.
In this pressurizing step, the liquid crystal material that has excessively entered by pressurizing usually at about 1.5 atm (152000 Pa) is extruded from the injection ports 3a and 3b.
Next, in this state, the injection port is sealed with an ultraviolet curing type sealing resin. At this time, the pressure difference between the inside and outside of the panel is 0.5 atm (50650 Pa).
[0012]
When the pressure is further released and returned to 1 atm, the sealing resin is slightly sucked into the panel. At this time, when the ultraviolet ray is irradiated, the sealing resin is cured, and a liquid crystal panel having a constant pressure difference between inside and outside is produced.
[0013]
[Problems to be solved by the invention]
However, in the above-described conventional method of manufacturing a liquid crystal panel, the variation in the gap is relatively large in the display region of the panel, and even in the liquid crystal panel manufactured in the same process, the gap value varies in each liquid crystal panel. There's a problem.
[0014]
The variation of the gap in the panel surface is generally ± 0.1 μm or more when a normal TN liquid crystal panel is formed with a gap of 5 μm.
In particular, in the case of a substrate having a step such as a thin film transistor (TFT) array, the thickness may be ± 0.3 μm or more.
In order to obtain display performance with high display quality, a TFT-type liquid crystal panel is required. Conventionally, however, this TFT-type liquid crystal panel can sufficiently withstand the above gap accuracy as a product. there were. This is because the TFT type liquid crystal panel employs a TN normally white mode in which black is displayed by applying a voltage, and in this display method, variations in panel gap did not significantly affect display uniformity.
[0015]
However, in recent years, efforts to expand the viewing angle, which has been the greatest drawback of liquid crystal panels, have been actively pursued, and when the display method is improved, gap variations of ± 0.1 μm are no longer allowed. ing.
For example, in the film phase compensation method which is one of the viewing angle enlarging methods, it is necessary to strictly match the product Δn · d of the gap d of the liquid crystal panel and the refractive index anisotropy Δn of the liquid crystal with the phase difference of the film. Therefore, the gap d is required to have a gap accuracy of at least ± 0.1 μm or less.
[0016]
In the IPS (In-Plane-Switching) system, which is another system for enlarging the viewing angle, Δn · d must be strictly controlled because the birefringence of the liquid crystal is used. Accuracy of 0.05 μm or less is required.
The reason why gap variation occurs in the conventional manufacturing method is as follows.
[0017]
In the pressurizing step, the liquid crystal panel is sandwiched by a pressurizing device to press the substrate and extrude the liquid crystal through the injection port. It is not immediately extruded from the injected injection port, and it takes a lot of time to reach a certain gap corresponding to the pressure.
Further, even if the substrate is pressed uniformly, the flow of the liquid crystal concentrated on the narrow injection port causes a distribution in the amount of liquid crystal in the panel. That is, in general, when the liquid crystal is concentrated near the injection port and rapid pressure sealing is performed, the gap near the injection port tends to be thick.
[0018]
For these reasons, in the pressure sealing step, the pressure is increased as slowly as possible, and a liquid crystal panel with high gap accuracy cannot be produced unless the pressure is maintained at a constant pressure for a long time.
In Japanese Patent Publication No. 7-66127, a panel after injecting liquid crystal is placed in a vacuum packaging material in which a sealing resin is sealed by heat sealing so that an injection hole faces the sealing resin sealed by heat. A method for manufacturing a liquid crystal panel to be vacuum-packed is disclosed.
[0019]
However, in this manufacturing method, the panel after the liquid crystal has been injected is set in the vacuum packaging material without applying the sealing resin, so it is necessary to insert the panel so that the injection port always faces the sealing resin. A decrease in efficiency may occur.
Further, when the sealing resin is sealed by heat sealing, there is a possibility that the sealing resin is hardened by heat and the injection port is not sealed, or the sealing resin is deteriorated by heat to contaminate the liquid crystal.
[0020]
The present invention solves the above problems and provides a liquid crystal panel manufacturing method capable of easily and quickly manufacturing a liquid crystal panel having a highly uniform cell gap of ± 0.05 μm or less and having high display uniformity. With the goal.
[0021]
[Means for Solving the Problems]
A method of manufacturing a liquid crystal panel according to the present invention is characterized in that a vacuum pack is applied to the panel after liquid crystal is injected by a vacuum injection method.
According to the present invention, a uniform cell gap can be easily formed, and a liquid crystal panel having excellent display uniformity can be obtained.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Method of manufacturing a liquid crystal panel according to claim 1, wherein the bonding two substrates facing with sealing resin, the panel was formed by filling the liquid crystal from the injection port by a vacuum injection method, the panel pressing press apparatus Extruding excess liquid crystal by pressurizing, applying the sealing resin to the inlet, releasing the pressure and allowing the sealing resin to enter near the sealing resin, and putting the panel after releasing the pressure into a bag. the interior of the bag under reduced pressure so that the sealing resin is extruded slightly and vacuum packed Te, characterized by curing the sealing resin in this state.
[0023]
According to this configuration, by curing the sealing resin in that state after vacuum packing, a uniform pressure can be applied to the entire surface of the panel, and a liquid crystal panel having a uniform cell gap can be realized.
Method of manufacturing a liquid crystal panel according to claim 2, wherein the bonding the two substrates that face in sealing resin, the panel was formed by filling the liquid crystal from the injection port by a vacuum injection method, the panel pressing press apparatus Extruding the excess liquid crystal by pressurizing, applying the UV-curable sealing resin to the injection port, then releasing the pressure and allowing the UV-curable sealing resin to enter the vicinity of the seal resin, and then releasing the pressure. The inside of the bag is vacuum-packed by placing the panel in a bag and the inside of the bag is depressurized so that the sealing resin is slightly extruded . In this state, the ultraviolet curing sealing resin is irradiated with ultraviolet rays and cured, and then the panel is annealed. It is characterized in that processing is performed and the vacuum pack is released.
[0024]
According to this configuration, since the annealing process is performed in a state of vacuum packing, the viscosity of the liquid crystal decreases, the flow speed increases, and the time required for transition to a uniform gap can be reduced.
Method of manufacturing a liquid crystal panel according to claim 3, wherein the bonding the two substrates that face in sealing resin, the panel was formed by filling the liquid crystal from the injection port by a vacuum injection method, the panel pressing press apparatus Extruding the excess liquid crystal by pressurizing, applying the thermosetting sealing resin to the injection port, then releasing the pressurization, allowing the thermosetting sealing resin to enter the vicinity of the seal resin, and then releasing the pressurization. the panel depressurizing the inside of the bag so that the thermosetting sealing resin is vacuum packed in a bag is pushed out slightly, after curing the sealing resin with annealed to the panel in this condition, the vacuum The pack is released.
[0025]
According to this configuration, the annealing process and the hardening of the sealing resin can be realized at the same time, the manufacturing process can be shortened, and the deterioration of the liquid crystal due to the irradiation of ultraviolet rays can be prevented.
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 5.
The same components as those in FIG. 6 showing the above-mentioned conventional example are denoted by the same reference numerals and described.
[0026]
(Embodiment 1)
1 to 4 show (Embodiment 1) of the present invention.
The configuration is almost the same as that of FIG. 6 showing the above-mentioned conventional example, except that the liquid crystal panel is manufactured in the process shown in FIG. 1A and the cell gap is made uniform.
[0027]
First, a pair of substrates is bonded with a seal resin 2 to produce a panel 1 having a gap between the substrates of about 5 mm.
The display screen size of the panel 1 is 10.4 type, and the size of the display area surrounded by the sealing resin 2 is 215 mm × 162 mm. In addition, the width of each of the injection ports 3a and 3b is 8 mm.
[0028]
In step S1, liquid crystal is injected into the panel 1 by a vacuum injection method. In order to sufficiently fill the panel 1 with the liquid crystal, the center portion of the panel 1 has a larger gap than the outer peripheral portion coated with the sealing resin.
FIG. 2 shows the gap distribution of the panel when liquid crystal was injected.
2 and FIG. 3 and FIG. 4, which will be described later, the numerical values in the figures indicate the gap value (unit: μm) of the panel at that position, and the dotted lines and solid lines in the figures respectively indicate the gap isolines.
[0029]
As shown in FIG. 2, the central part of the panel after liquid crystal injection is about 0.3 μm thicker than the outer peripheral part where the sealing resin 2 is applied.
In step S2, the panel 1 filled with the liquid crystal is sandwiched between pressurizing presses and pressurized at a pressure of about 50,000 Pa to push out excess liquid crystal.
Then, it was confirmed that excessively filled liquid crystal permeated through the injection ports 3a and 3b. In step S3a, an ultraviolet-curable sealing resin was applied to the injection ports 3a and 3b while the panel was sandwiched by the pressure press device. Apply.
[0030]
Next, the panel is taken out from the pressure press device to release the pressurization, and the sealing resin is caused to enter into the vicinity of the sealing resin by the respiration of the panel 1.
FIG. 3 shows the gap of the liquid crystal panel at this time.
Compared to FIG. 2 showing the gap state immediately after the injection of the liquid crystal, the center portion of the panel is thinner by 0.2 μm, and the gap distribution is thinner at the center portion of the panel, but the gap distribution is smaller. Conversely, the cell gap increases near 3b, and it is clear that the uniformity of the gap is worse than that in FIG.
[0031]
In step S4, the panel after the pressurization is released is put in a resin bag and vacuum-packed using a vacuum-packing device.
The pressure of the vacuum packing apparatus is set to about 50,000 Pa, and the pressure is set so that the panel is pressed at substantially the same pressure as that of the above-described pressure press apparatus.
If left in this state for a while, the sealing resin has not been cured yet, so that the sealing resin drawn into the panel to the inside of the sealing resin is slightly extruded from the injection ports 3a and 3b. Further, since a uniform pressure is applied to the entire surface of the panel, the liquid crystal in the panel flows and the gap becomes uniform.
[0032]
In step S5, the sealing resin is cured by irradiating ultraviolet rays to the sealing resin in a vacuum packed state.
Then, the liquid crystal panel is taken out of the resin bag, and the vacuum pack is released.
As shown in FIG. 4, the gap distribution of the liquid crystal panel 1 formed in such a process is very uniform within 0.05 μm over the entire surface of the panel, and a liquid crystal panel with good display uniformity is obtained.
[0033]
In the above (Embodiment 1), the vacuum pack is released after the sealing resin is cured in step S5. However, the present invention is not limited to this, and as shown in FIG. After the sealing resin is cured in S5, an annealing process may be performed as step S6 in a vacuum packed state.
When the liquid crystal panel is heated in a vacuum-packed state, that is, under a uniform pressurized state, the viscosity of the liquid crystal decreases and the flow speed increases, so that the time required for transition to a uniform gap can be reduced.
[0034]
Also, in the liquid crystal panel manufactured in the process shown in FIG. 1A, since the vacuum pack is released, an annealing process for stabilizing the alignment of the liquid crystal is performed. The number does not increase.
When the liquid crystal panel is placed in a resin bag, the uniform pressurizing effect when packed is the same regardless of the orientation of the panel, that is, regardless of the position of the inlets 3a and 3b. Therefore, in the step of packing the liquid crystal panel in a resin bag, there is no restriction on the direction in which the panel is inserted, so that there is no erroneous operation determination due to the addition of this step, and a decrease in work efficiency can be prevented.
[0035]
(Embodiment 2)
FIG. 5 shows (Embodiment 2) of the present invention.
In the above (Embodiment 1), an ultraviolet curable resin is used as the sealing resin, but in this (Embodiment 2), a thermosetting material is used as the sealing resin.
Although substantially the same as the step shown in FIG. 1B, in this (Embodiment 2), the annealing treatment in step S6 cures the sealing resin which is a thermosetting material. The step and the curing step of the sealing resin can be used in common.
[0036]
Therefore, the step of curing the sealing resin in step S5 in FIG. 1B is not required, and the manufacturing process can be simplified. Further, the degradation of the liquid crystal due to the irradiation of ultraviolet rays can be prevented, and a liquid crystal panel with good display quality can be obtained.
[0037]
【The invention's effect】
As described above, according to the method for manufacturing a liquid crystal panel of the present invention, a liquid crystal panel having a gap accuracy of ± 0.05 μm or less can be obtained easily and in a short time.
[Brief description of the drawings]
FIG. 1 is a view showing a manufacturing process of a liquid crystal panel in (Embodiment 1). FIG. 2 is a plan view of the liquid crystal panel showing distribution of a gap of the liquid crystal panel after injecting liquid crystal in (Embodiment 1). FIG. 4 is a plan view of a liquid crystal panel showing a gap distribution of a liquid crystal panel before vacuum packing according to the first embodiment. FIG. 4 is a plan view of a liquid crystal panel showing a gap distribution of the liquid crystal panel obtained in the first embodiment. FIG. 5 is a view showing a manufacturing process of the liquid crystal panel in (Embodiment 2). FIG. 6 is a plan view of a conventional liquid crystal panel.
1 LCD panel 2 Sealing resin 3a, 3b Injection

Claims (3)

The two opposing substrates are stuck together with a sealing resin, and liquid crystal is filled from an injection port by a vacuum injection method to form a panel, and the panel is pressed by a pressure press to extrude excess liquid crystal. After applying the sealing resin to the entrance, the pressure is released to allow the sealing resin to enter the vicinity of the sealing resin, and the panel after the pressure is released is put in a bag, vacuum-packed, and the sealing resin is slightly extruded. A method of manufacturing a liquid crystal panel in which the inside of the bag is decompressed so that the sealing resin is cured in this state. The two opposing substrates are stuck together with a sealing resin, and liquid crystal is filled from an injection port by a vacuum injection method to form a panel, and the panel is pressed by a pressure press to extrude excess liquid crystal. After applying the UV-curable sealing resin to the entrance, the pressure is released to allow the UV-curable sealing resin to enter the vicinity of the sealing resin, and the panel after releasing the pressure is put in a bag and vacuum-packed. The inside of the bag is depressurized so that the sealing resin is slightly extruded , and in this state, the ultraviolet-curing sealing resin is cured by irradiating ultraviolet rays, and then the panel is annealed to release the vacuum pack. Production method. The two opposing substrates are stuck together with a sealing resin, and liquid crystal is filled from an injection port by a vacuum injection method to form a panel, and the panel is pressed by a pressure press to extrude excess liquid crystal. After applying the thermosetting sealing resin to the inlet, the pressure is released to allow the thermosetting sealing resin to enter into the vicinity of the sealing resin, and the panel after releasing the pressure is put in a bag and vacuum-packed. depressurizing the inside of the bag so that the thermosetting sealing resin is extruded slightly, after curing the sealing resin with annealed to the panel in this state, a method of manufacturing a liquid crystal panel for releasing the vacuum packing.

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