JP3658604B2 - Manufacturing method of liquid crystal panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dripping injection method that does not require an injection port, which has been studied as a simplified process of liquid crystal injection, and diffuses liquid crystal after curing by using a thermoplastic photo-curing seal as the main seal. Thus, a gap is created to provide a liquid crystal panel free from alignment disturbance in the vicinity of the seal.
[0002]
[Prior art]
In the conventional drop injection method, after the gap is formed, the seal is cured after positioning, but there is a problem with the compatibility of the uncured seal with the liquid crystal and the damage that ultraviolet light gives to the liquid crystal when using an ultraviolet curable resin. As a result, alignment disorder occurred during sealing.
In addition, a method in which the seal portion is doubled and the inner seal is made of an inactive resin for the liquid crystal has been proposed (see Japanese Patent Laid-Open No. Sho 4-60518). However, since the seal area is enlarged, an outer frame for the display area is proposed. There was a problem that the ratio of dimensions would increase.
[0003]
FIG. 4 is a process explanatory diagram of a conventional liquid crystal dropping method, and (A) and (B) show each process.
In this figure, 21 is a first substrate, 22 is a sealing agent, 23 is a liquid crystal, 24 is a second substrate, 25 is an adhesive spacer, 26 is a lower stage, 27 is a guide, 28 is an upper stage, 29 is a guide, Reference numeral 30 denotes a holding plate.
[0004]
A conventional method for manufacturing a liquid crystal panel will be described with reference to this process diagram.
First, a sealant 22 of a photocurable resin is applied to the first substrate 21 in a frame shape, and the liquid crystal 23 is uniformly dropped at a required amount corresponding to the cell thickness into the frame.
Separately, adhesive spacers 25 are dispersed on the second substrate 24 to perform heat fixing.
[0005]
Then, the first substrate 21 is placed on the lower stage 26 in the vacuum chamber and fixed by the guide 27, the second substrate 24 is positioned on the upper stage 28 by the guide 29, and is held by the holding plate 30 to be held in the first stage. It is set above the substrate 21 (see FIG. 4A so far).
[0006]
Then, after evacuation, the holding plate 30 is removed, the lower stage 26 is raised, the first substrate 21 and the second substrate 24 are bonded together, and the gap between the panels is pressed by atmospheric pressure or pressing. Make out.
In addition, alignment is performed after gap formation, and the seal is cured by heat or light (see FIG. 4B so far).
[0007]
[Problems to be solved by the invention]
FIGS. 5A and 5B are explanatory diagrams of problems caused by a conventional liquid crystal panel manufacturing method using a dropping injection method. FIGS. 5A and 5B show different problems.
In this figure, 31 is a first substrate, 32 is a second substrate, 33 is a liquid crystal, and 34 is a seal.
[0008]
First problem (see FIG. 5A)
Before the seal 34 made of ultraviolet curable resin around the liquid crystal 33 sandwiched between the first substrate 31 and the second substrate 32 is cured in a short time, the liquid crystal 33 is covered with a light shielding mask 35 and irradiated with ultraviolet rays. Although cured, there is a problem that the liquid crystal 33 at the interface of the seal 34 is irradiated with ultraviolet rays to the region shown by oblique lines due to the wraparound of light, and the liquid crystal 33 deteriorates.
[0009]
Second problem (see FIG. 5B)
Since the seal 34 is cured after the panel gap is provided, the liquid crystal 33 is contaminated by the uncured seal 34, or conversely, the seal 34 is eroded and leaks.
[0010]
In the sealing process, the uncured seal does not bleed into the liquid crystal, the liquid crystal does not erode the uncured seal, seal leakage can be suppressed, and the ultraviolet light irradiated for sealing is used. An object is to provide a dropping injection method in which liquid crystal is not deteriorated.
[0011]
[Means for Solving the Problems]
FIG. 1 is a diagram for explaining the principle of a method for producing a liquid crystal panel according to the present invention, wherein (A) and (B) show the respective steps.
In this figure, 1 is a first substrate, 2 is a sealant, 3 is a liquid crystal, 5 is a second substrate, 6 is an adhesive spacer, 7 is a lower stage, 8 is a guide, 13 is an ultraviolet source, and 14 and 16 are A hot plate, 15 is a guide, and VC is a vacuum chamber.
Since the reference numerals in this figure are the same as those in FIGS.
[0012]
The manufacturing method of the liquid crystal panel of the present invention will be described with reference to this principle explanatory diagram.
First, a sealant 2 of a photocurable resin is applied to the first substrate 1 in a frame shape, and the liquid crystal 3 is uniformly dropped into the frame by a necessary amount corresponding to the cell thickness.
Separately, adhesive spacers 6 are sprayed on the second substrate 5 to perform heat fixing.
[0013]
Then, the first substrate 1 is placed on the lower stage 7 in the vacuum chamber and fixed by the guide 8, the second substrate 5 is set above the first substrate 1, vacuuming is performed, and then the lower stage 7 is raised to bond the first substrate 1 and the second substrate 5 together.
[0014]
The lower stage 7 is pushed up while aligning the alignment marks of the first substrate 1 and the second substrate 5 until the gap is sufficiently pressed, and the sealing material 2 is irradiated with ultraviolet rays from the ultraviolet source 13 to irradiate the sealing part. After curing, the vacuum chamber VC is opened to atmospheric pressure (see FIG. 1A so far).
[0015]
Next, the bonded first substrate 1 and second substrate 5 are fixed on a heated hot plate 14 by a guide 15 and sandwiched from above and below by another hot plate 16 heated to the same temperature. The liquid crystal 3 heated to a temperature higher than the NI transition temperature by the hot plates 14 and 16 has a greatly reduced viscosity and is an isotropic liquid, so that the occurrence of disclination during injection can be suppressed.
Moreover, the distortion at the time of photocuring can be relieve | moderated by applying the heat | fever more than a glass transition point to the sealing agent 2, and performing the pressurization, and can improve adhesive strength.
[0016]
After the gap between the first substrate 1 and the second substrate 5 is formed, the bonded substrate is fixed on a hot press or on a hot plate heated to the same temperature to perform precise alignment, and the first The substrate 1 and the second substrate 5 bonded together are gradually cooled to room temperature.
It is also possible to apply a UV curable resin having a glass transition point higher than that of the main seal formed by the sealant 2 on the edge of the panel and irradiate the UV to double-fix the panel (FIG. 1B so far). reference).
[0017]
In the present invention characterized by the above process,
(1) In a drop injection method in which a main seal is formed and a liquid crystal is dropped into a display area in advance and a counter substrate is bonded together in a vacuum and liquid crystal is injected by returning to atmospheric pressure. By using a thermoplastic photo-curing resin having a glass transition point between the N-I transition temperatures of the liquid crystal and performing a panel gap after the seal is cured, before the liquid crystal is diffused to the sealing after the substrates are bonded together The seal can be light-cured, and the panel gap can be removed by hot pressing after releasing the atmospheric pressure. The uncured sealant does not come into contact with the liquid crystal, and the liquid crystal is exposed to light (ultraviolet rays) so that it deteriorates. Nothing is gone.
[0018]
Further, in this case, if photocuring is performed in a vacuum, diffusion of the liquid crystal during sealing can be suppressed, and the seal can be cured before the liquid crystal reaches the main seal.
[0019]
Also, in this case, as a panel gap extraction process after the seal is cured, the entire panel is pressed with parallelism by processing while heating the substrate above the glass transition point of the seal on a pair of flat hot plates. Since the panel gap is formed on a pair of hot plates (hot press) and the liquid crystal can be diffused in the plane, the curing distortion of the seal can be taken and the adhesion to the substrate can be improved.
[0020]
Further, in this case, as a gap forming process after the seal is cured, by applying pressure while heating the substrate above the glass transition point of the seal and above the NI transition temperature of the liquid crystal on a pair of flat hot plates. It is possible to relax the alignment regulating force in the liquid crystal diffusion direction and prevent the occurrence of disclination.
[0021]
Further, in this case, by performing precise positioning on a hot plate heated to the same temperature following the gap forming step, the substrate can be moved with a small frictional force, and the load on the seal and spacer can be reduced.
[0022]
Further, in this case, after the gap forming step, the panel side is fixed with a resin having a glass transition point higher than that of the main seal, whereby thermal deformation after the panel formation can be suppressed.
[0023]
In the liquid crystal panel manufacturing method of the present invention, the uncured seal and the liquid crystal are not in contact with each other in the dropping injection method, and the liquid crystal is not irradiated with light (ultraviolet rays). The
(1) Since the ineffective seal does not bleed into the liquid crystal, disorder of alignment during sealing can be suppressed.
(2) Since the liquid crystal does not erode the uncured seal, seal leakage can be suppressed.
(3) Since the ultraviolet light is irradiated only on the seal, the deterioration of the liquid crystal is eliminated.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
2 and 3 are process explanatory diagrams of the liquid crystal dropping method according to the embodiment of the present invention, and (A) to (G) show each process.
In these drawings, 1 is a first substrate, 2 is a sealing agent, 3 is a liquid crystal, 4 is a dispenser, 5 is a second substrate, 6 is an adhesive spacer, 7 is a lower stage, 8 is a guide, and 9 is an upper stage. 10 is a holding plate, 11 is a CCD camera, 12 is a guide, 13 is a UV source, 14 is a hot plate, 15 is a guide, 16 is a hot plate, 17 and 18 are hot presses, 19 is a CCD camera, and 20 is UV cured. Resin.
With reference to this process explanatory diagram, the panel forming process after the formation of the seal in the liquid crystal dropping method of the embodiment of the present invention will be described.
[0025]
First step (see FIG. 2A)
A photocurable resin sealant (Luxtrak, glass transition point 59 ° C.) 2 is applied to the first substrate 1 using a dispenser (not shown), and liquid crystal (Merck, ZLI-4792, N-I transition temperature 91 ° C.) 3 is uniformly dropped at a required amount corresponding to the cell thickness using a dispenser 4 equipped with an electromagnetic control valve.
[0026]
Second step (see FIG. 2B)
Adhesive spacers (manufactured by Hayakawa Rubber, 5.0 μm diameter, 150 ° C. heat melting type) 6 are sprayed on the second substrate 5, and heat setting is performed at 150 ° C. for 1 hour.
[0027]
Third step (see FIG. 2C)
The first substrate 1 is placed on the lower stage 7 in the vacuum chamber and fixed by the guide 8, the second substrate 5 is set above the first substrate 1 by engaging the holding plate 10 with the upper stage 9, The combination is performed while monitoring by the CCD camera 11 and then stopped by the guide 12 for positioning.
After evacuation, the holding plate 10 is removed, the lower stage 7 is raised, and the first substrate 1 and the second substrate 5 are bonded together.
[0028]
Fourth step (see FIG. 2D)
The lower stage 7 is pushed up while aligning the alignment marks of the first substrate 1 and the second substrate 5 to a gap (˜10 μm) enough to press the seal, and the ultraviolet ray source 13 irradiates the seal part with ultraviolet rays. After the sealant 2 is cured, the guide 12 that has fixed the second substrate is removed and the pressure is released to atmospheric pressure.
[0029]
5th process (refer FIG.3 (E))
The bonded first substrate 1 and second substrate 5 are fixed on a hot plate 14 heated to 100 ° C. by a guide 15 and sandwiched from above and below by another hot plate 16 heated to the same temperature. .
The liquid crystal 3 heated to a temperature higher than the NI transition temperature by the hot plates 14 and 16 has a greatly reduced viscosity and is an isotropic liquid, so that the occurrence of disclination during injection can be suppressed.
Moreover, the distortion at the time of photocuring can be relieve | moderated by applying the heat | fever more than a glass transition point to the sealing agent 2, and performing the pressurization, and can improve adhesive strength.
By this step, the liquid crystal 3 spreads uniformly in the panel surface, and a uniform panel gap is formed.
[0030]
6th process (refer FIG.3 (F))
After the gap between the first substrate 1 and the second substrate 5 is made, the bonded substrate is fixed on the hot press 17 or 18 or on a hot plate heated to the same temperature, and the CCD camera 19 is fixed. Use for precise alignment.
[0031]
Seventh step (see FIG. 3G)
After bonding the first substrate 1 and the second substrate 5 to each other and gradually cooling to room temperature, the second substrate 5 is cut into a panel size by a scribe break.
Then, an ultraviolet curable resin (made by Three Bond, glass transition point 140 ° C.) 20 having a glass transition point higher than that of the main seal formed by the sealant 2 is applied to the edge of the panel, and the panel is double-fixed by irradiating ultraviolet rays. .
[0032]
【The invention's effect】
As described above, according to the method for manufacturing a liquid crystal panel of the present invention, after the seal is cured, the liquid crystal is diffused to the seal and gaps are created, so that alignment disorder in the vicinity of the seal is suppressed and heating is performed. Since the gap is formed, a panel with a uniform orientation can be obtained.
[Brief description of the drawings]
FIGS. 1A and 1B are explanatory views of the principle of a method for manufacturing a liquid crystal panel according to the present invention, and FIGS.
FIG. 2 is a process explanatory diagram (1) of a liquid crystal dropping method according to an embodiment of the present invention, and (A) to (D) show each process.
FIG. 3 is a process explanatory diagram (2) of the liquid crystal dropping method according to the embodiment of the present invention, and (E) to (G) show each process.
FIG. 4 is a process explanatory diagram of a conventional liquid crystal dropping method, and (A) and (B) show each process.
FIGS. 5A and 5B are explanatory diagrams of problems caused by a conventional liquid crystal panel manufacturing method using a dropping injection method, and FIGS. 5A and 5B show different problems. FIGS.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st board | substrate 2 Sealing agent 3 Liquid crystal 4 Dispenser 5 2nd board | substrate 6 Adhesive spacer 7 Lower stage 8 Guide 9 Upper stage 10 Holding plate 11 CCD camera 12 Guide 13 Ultraviolet source 14 Hot plate 15 Guide 16 Hot plates 17, 18 Hot press 19 CCD camera 20 UV curable resin VC Vacuum chamber

Claims (6)

In the dropping injection method in which the main seal is formed and the liquid crystal is dropped into the display region in advance, the substrate and the counter substrate are bonded together in a vacuum, and liquid crystal is injected by returning to atmospheric pressure.
A thermoplastic photo- curing resin having a glass transition point between room temperature and the NI transition temperature of the liquid crystal is used for the main seal, and the seal is cured before the liquid crystal reaches the main seal. A method of manufacturing a liquid crystal panel, comprising heating a substrate to a temperature equal to or higher than a transition point, softening a main seal, and generating a panel gap. Method of manufacturing a liquid crystal panel according to claim 1, characterized in that the seal cured by light irradiation to the main seal in a vacuum. As a panel gap-step after sealing the curing, a method of manufacturing a liquid crystal panel according to claim 1, wherein the pressurized while heating the base plate on a pair of flat hot plate. As gap-step after sealing the curing, a method of manufacturing a liquid crystal panel according to claim 1, wherein the pressurizing while heating the substrate to N-I transition temperature above the temperature of the liquid crystal. 2. The method of manufacturing a liquid crystal panel according to claim 1, wherein, following the gap forming step, precise alignment is performed on a hot plate heated to the same temperature. 2. The method of manufacturing a liquid crystal panel according to claim 1, wherein after the gap formation step, the panel side is fixed with a resin having a glass transition point higher than that of the main seal to suppress thermal deformation after the panel formation.

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