JPH11212045A - Manufacture of liquid crystal panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture the panel excellent in display quality and free from abnormal orientation by sufficiently setting UV curing resin adhering an extraction electrode substrate and a light shield substrate by the manufacturing method using liquid crystal dripping. SOLUTION: After UV curing seal resin 81 is formed at the periphery of the display area of a glass substrate 1 which has an extraction electrode 42 formed of a metallic thin film or glass substrate 1 having a light shield film 21 at the periphery of the display area and a liquid crystal material 7 is dripped by a specific amount in the display area of one of the substrates, the two substrates are put one over the other and irradiated with ultraviolet rays from the glass substrate side having the metallic extraction electrode 42 or both the side of the two substrates to set the seal resin 81.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal panel, and more particularly to a method for bonding two glass substrates sandwiching a liquid crystal.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIGS. The method of assembling the liquid crystal panel is roughly classified into 2
The following construction methods have been proposed.

[0003] First, after a glass substrate is bonded and an empty cell as shown in FIGS. 9 to 11 is assembled, the empty cell is evacuated, and the vacuum pressure in the empty cell and the atmospheric pressure are reduced. This is a method of injecting a liquid crystal material using a pressure difference (vacuum injection method). In the case of the vacuum injection method, the upper and lower glass substrates 1 are attached to each other, and after the sealing resin 8 is sufficiently cured, a liquid crystal material is injected. As the material of the sealing resin 8, a thermosetting type and an ultraviolet setting type can be arbitrarily selected according to the panel configuration.

In recent years, in response to a demand for space saving of a liquid crystal panel, a configuration in which a sealing resin 8 overlaps a light shielding film 2 around a display area as shown in FIGS. When the sealing resin is used, the sealing resin 8 can be sufficiently cured regardless of the positional relationship with the light shielding film 2. Most of the liquid crystal panels produced to date have been assembled by this vacuum injection method, and this is the method whose conditions have been studied the most.

A second method is a method of dropping a liquid crystal material on one substrate and then bonding the other substrate (dropping method). This method is expected to be a next-generation assembly method because the throughput of panel production is short and the use efficiency of liquid crystal materials is high.

However, since the liquid crystal material is in direct contact with the uncured sealing resin, the alignment of the liquid crystal is likely to be disordered. In order to stabilize the liquid crystal alignment as much as possible, a UV-curable sealing resin which can be rapidly cured. Materials are used.

[0007]

When a liquid crystal panel is manufactured by the dropping method, an ultraviolet-curable sealing resin is used as described above. At this time, it is necessary to irradiate the sealing resin with ultraviolet rays having sufficient energy. In addition, the design around the display area of the panel and the method of irradiating ultraviolet rays need to be restricted.

In particular, in a liquid crystal panel using a metal lead-out electrode, such as a TFT liquid crystal panel or a reflection type liquid crystal panel using reflection by an electrode, the sealing resin is irradiated with ultraviolet light regardless of whether ultraviolet irradiation is performed from above or below the panel. An area where the sealing cannot be performed occurs. In the vicinity of this area, the curing of the sealing resin becomes insufficient, and the liquid crystal alignment is not stabilized.

Therefore, in order to manufacture a liquid crystal panel in which extraction electrodes are formed of metal by using the dropping method, it is necessary to use FIG.
As shown in FIG. 2, an ultraviolet-curable sealing resin 81 is applied to the outer periphery of the light-shielding film 2 around the display area, and the ultraviolet-ray-shielding mask 91 is applied from the substrate side where the light-shielding film 2 is located.
It is necessary to perform 0 irradiation. In the case of a configuration in which a sealing resin is overlaid on the light shielding film 2 around the display area as shown in FIGS. 9 and 10 to save space in the peripheral area, the metal extraction electrode 42 or the shadow of the light shielding film 2 is not used. To become a seal resin 8
Has not been able to be cured sufficiently.

[0010]

In order to solve the above problems, the width of the extraction electrode and the distance between adjacent electrodes (region where no electrode is formed: width between electrodes) are limited for each material of the light shielding film. It is effective to irradiate the ultraviolet rays from the side of the substrate having the extraction electrodes, or to irradiate the ultraviolet rays from both sides of the two bonded substrates.

As described above, by restricting the design of the width of the extraction electrode and the width of the extraction electrode, the ultraviolet light incident on the sealing resin from between the electrodes can be reflected on the light-shielding film surface of the opposing substrate or can be reflected on the light-shielding film surface. Due to multiple reflection by the electrode surface and furthermore scattering by the filler material in the sealing material, it is possible to sufficiently irradiate the shadow area of the electrode, and there is a chain reaction of the photoinitiator in the sealing resin, and The sealing resin in the shadow region can be sufficiently cured.

[0012]

1 to 6 show a cross section of a main part of a TFT liquid crystal panel according to an embodiment of the present invention. Here, 1 is a glass substrate, 13 is an extraction electrode substrate made of metal, 14 is a light shielding substrate, 21 is a metal light shielding film,
22 is a light-shielding film made of resin, 31, 32, and 33 are red, green, and blue color filters, respectively, and 41 is a transparent electrode (IT
O), 42 is a metal extraction electrode, 5 is an overcoat,
6 is an alignment film, 7 is a liquid crystal material, 71 is spacer particles, 8
Reference numeral 1 denotes an ultraviolet-curable seal resin, 90 denotes ultraviolet rays, and 91 denotes an ultraviolet light shielding mask.

FIGS. 1 to 3 show the case where a metal thin film such as Cr is used as the light-shielding film 21 and FIGS. 4 to 6 show the case where a resin light-shielding film containing a black pigment is used as the light-shielding film 22. FIG.
6 to FIG. 6 show a case where irradiation with ultraviolet light 90 is performed from the extraction electrode substrate 13 side and a case where irradiation is performed from both sides of the extraction electrode substrate 13 and the light shielding substrate 14 using the respective cross-sectional views.

The width of the extraction electrode and the width between the electrodes (the width of the region where no electrode is formed between the adjacent electrodes) are determined by the material of the light-shielding film and the method of irradiating ultraviolet rays (from the extraction electrode substrate 13 side).
(Table 4)
It is restricted as follows.

[0015] If the irradiation of the ultraviolet rays is equal to or more than a certain energy, the amount of the ultraviolet irradiation energy hardly affects the above-mentioned limit.

Next, specific embodiments of the present invention will be described with reference to FIGS. 7, 8, (Table 1), (Table 2-1), (Table 2-2),
This will be described with reference to (Table 3) and (Table 4).

(Example 1) FIG. 7 and (Table 1) show a process of applying a photoresist to a glass substrate having a Cr film formed thereon, irradiating ultraviolet rays through a photomask, developing, etching, and stripping the resist. The Cr pattern substrates 10 of A to O shown were prepared. This Cr pattern has a configuration imitating a metal extraction electrode (simulated extraction electrode 43), and creates an area corresponding to the shadow of the extraction electrode when performing ultraviolet curing for sealing resin curing in a later step. It is formed for the purpose. The simulated electrode width 431 of A to O and the interelectrode width 432 are as shown in (Table 1).

[0018]

[Table 1]

A thermosetting resin made of an epoxy resin was applied to these Cr pattern substrates 10 using a spin coater, and was thermoset at 200 ° C. for 2 hours to form an overcoat 5. Next, a transparent electrode (ITO) 41 is formed on the entire surface by sputtering so as to have a thickness of 2000 to 2500 °, and is patterned in a stripe shape by a photolithography method to form a segment substrate 11 for an STN liquid crystal panel. (See FIG. 8).

On each of the segment substrate 11 and the color filter substrate 12 having a common pattern of ITO prepared in advance, an alignment film 6 made of polyimide
After forming to a film thickness of 0 to 1000 °, STN
A rubbing process was performed in a predetermined direction so as to be assembled as a liquid crystal panel. A light-shielding film 2 is formed on the color filter substrate 12, and two types of light-shielding films, one made of Cr and one made of a resin containing a black pigment, are prepared.

Next, an ultraviolet-curable epoxy acrylate seal resin 81 containing 1-2% of glass fiber having an average particle size of 7.0 μm is applied to the periphery of the display area of the segment substrate 11 by screen printing. Further, a predetermined amount of the liquid crystal material 7 was dropped on the display area. At this time, the sealing resin 81 was formed so as to overlap the pattern of the simulated extraction electrode 43 formed of Cr and to surround the display area.

On the other hand, on the color filter substrate 12, 200 to 300 spacer particles 71 made of resin and having an average particle diameter of 6.5 μm and having a fixing material are sprayed per square millimeter.
The substrate was fixed to the substrate by performing various heat treatments.

Next, the segment substrate 11 and the color filter substrate 12 are bonded together in a vacuum chamber such that the sealing resin 81 overlaps the light-shielding film 2 outside the display area of the color filter substrate 12 by half. After being taken out, the seal resin 81 was irradiated with ultraviolet light 90 to produce an STN liquid crystal panel shown in FIG. At this time, irradiation with ultraviolet light 90 was performed at 25 mW / cm ² (measured at 405 nm) for 5 minutes, and irradiation with light from the segment substrate 11 side, the segment substrate 11 and the color filter substrate 12 was performed.
Irradiated from both sides were prepared.

After subjecting these STN liquid crystal panels to thermal annealing at 130 ° C. for 30 hours, a voltage was applied to the panels to observe the stability of liquid crystal alignment. Observation results (Table 2-
1) and (Table 2-2).

Next, these prepared panels A to O were disassembled, the sealing resin 81 was peeled off, and FTIR analysis was performed to measure the degree of polymerization of the sealing resin. The measurement results are shown in (Table 2-1) and (Table 2-2).

[0026]

[Table 2-1]

[0027]

[Table 2-2]

(Embodiment 2) The STN liquid crystal panel of FIG. 8 is formed in the same manner as in Embodiment 1 by using A and M (the light shielding film 2 is made of both Cr and resin) among the Cr pattern substrates 10 formed in Embodiment 1. Created. At this time, the ultraviolet irradiation time during curing of the seal resin 81 was 1, 2, 3, 5, 10 minutes, and irradiation was performed from the segment substrate side. 140 ° C, 3
After performing thermal annealing for 0 hour to evaluate the stability of liquid crystal alignment, the panel is disassembled and each seal resin is replaced with F.
The degree of polymerization was measured by TIR analysis. The results are shown in (Table 3).

[0029]

[Table 3]

From Tables 2-1 and 2-2, the degree of curing of the ultraviolet curable seal resin 81 differs depending on the electrode width 431 and the electrode width 432 of the simulated extraction electrode 43 made of metal. It can be seen that there is a difference depending on the material of the light-shielding film 2 and the method of irradiating the ultraviolet light (which glass substrate is used for irradiation). This is because all the irradiated ultraviolet rays are not parallel rays and are not perpendicularly incident on the substrate surface, but include a large amount of oblique light, so that the reflected ultraviolet rays are reflected by the light shielding film 2 and the metal simulation electrode 43 and simulated. This is considered to be because irradiation is also performed on the sealing resin 81 in a region shaded by the electrode 43 and the light shielding film 2.

Table 3 shows that when the ultraviolet light irradiation energy is a fixed value (25 mW / cm ² , 3 minutes) or more, the ultraviolet light irradiation energy is lower than the electrode width 431, the electrode width 432, and the seal hardening degree. This indicates that there is almost no effect.

From these results, the design conditions of the extraction electrode when the liquid crystal panel using the metal extraction electrode is assembled using the ultraviolet irradiation type sealing resin are determined as shown in Table 4.

[0033]

[Table 4]

In this embodiment, in order to confirm the stability of the liquid crystal alignment, an STN liquid crystal panel in which the liquid crystal alignment is liable to be disturbed by the influence of the insufficient curing of the sealing resin is used. The same curing can be obtained with the liquid crystal panel of the above.

Based on these results, TFT liquid crystal panels (FIGS. 1 to 6) were prepared under the conditions shown in (Table 4), and it was confirmed that the panels were stable in liquid crystal orientation and good in display. . In these figures, for simplicity, illustration of parts not directly related to the present invention, such as a TFT array, is omitted.

[0036]

According to the present invention, by limiting the width of the metal extraction electrode and the width between the electrodes, it is possible to manufacture a liquid crystal panel having a stable liquid crystal orientation and a small display area periphery even when the dropping method is used. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a liquid crystal panel according to an embodiment of the present invention (a light-shielding film is a metal light-shielding film, and a sealing resin overlaps half of the light-shielding film, and ultraviolet rays are emitted from the extraction electrode substrate side).

FIG. 2 is a cross-sectional view of a main part of a liquid crystal panel according to an embodiment of the present invention (a light-shielding film is a metal light-shielding film, a sealing resin is overlapped with the light-shielding film by half, and ultraviolet rays are irradiated from both sides of the extraction electrode substrate and the light-shielding substrate).

FIG. 3 is a cross-sectional view of a main part of a liquid crystal panel according to an embodiment of the present invention (a light-shielding film is a metal light-shielding film, a sealing resin is entirely overlapped with the light-shielding film, and ultraviolet rays are irradiated from the extraction electrode substrate side).

FIG. 4 is a cross-sectional view of a main part of a liquid crystal panel according to an embodiment of the present invention (a light-shielding film is a resin-made light-shielding film, and a sealing resin overlaps half of the light-shielding film, and ultraviolet rays are irradiated from the extraction electrode substrate side).

FIG. 5 is a cross-sectional view of a main part of a liquid crystal panel according to an embodiment of the present invention (a light-shielding film is a resin-made light-shielding film, a sealing resin overlaps with the light-shielding film by half, and ultraviolet rays are emitted from both sides of the extraction electrode substrate and the light-shielding substrate).

FIG. 6 is a cross-sectional view of a main part of a liquid crystal panel according to an embodiment of the present invention (a light-shielding film is a resin-made light-shielding film, a sealing resin is entirely overlapped with the light-shielding film, and ultraviolet rays are irradiated from the extraction electrode substrate side).

FIG. 7 is a plan view of a main part of a simulated electrode pattern used in a specific example of the present invention.

FIG. 8 is a sectional view of a main part of an STN liquid crystal panel prepared in a specific embodiment of the present invention.

FIG. 9 is a cross-sectional view of a main part of a liquid crystal panel assembled by a vacuum injection method according to a conventional technique (a sealing resin entirely overlaps a light shielding film).

FIG. 10 is a cross-sectional view of a main part of a liquid crystal panel assembled by a vacuum injection method according to a conventional technique (a sealing resin partially overlaps a light shielding film).

FIG. 11 is a cross-sectional view of a main part of a liquid crystal panel assembled by a vacuum injection method according to a conventional technique (a sealing resin does not overlap a light shielding film).

FIG. 12 is a cross-sectional view of a main portion of a liquid crystal panel assembled by a liquid crystal dropping method according to a conventional technique (a sealing resin does not overlap a light shielding film, and ultraviolet light is irradiated from the light shielding substrate side).

[Explanation of symbols]

 Reference Signs List 1 glass substrate 2 light shielding film 5 overcoat 6 alignment film 7 liquid crystal material 8 seal resin 10 Cr pattern substrate 11 segment substrate 12 color filter substrate 13 lead electrode substrate 14 light shielding substrate 21 metal light shielding film 22 resin light shielding film 31 color filter ( Red) 32 Color filter (Green) 33 Color filter (Blue) 41 Transparent electrode (ITO) 42 Extraction electrode 43 Simulated extraction electrode 71 Spacer particle 81 Ultraviolet curing seal resin 90 Ultraviolet 91 Ultraviolet light shielding mask 431 Electrode width 432 Electrode width

Claims (8)

[Claims] 1. A glass substrate having an extraction electrode formed of a metal thin film, and a glass substrate having a light-shielding film formed of a metal thin film around a display region. After applying a mold sealing resin and further dropping a predetermined amount of liquid crystal material on a display area of one of the substrates, the two substrates are overlapped, and ultraviolet rays are irradiated from a glass substrate side having a metal extraction electrode. A method for manufacturing a liquid crystal panel, comprising a step of bonding a glass substrate to cure a sealing resin. 2. The method according to claim 1, wherein the width of the extraction electrode in a region overlapping with the ultraviolet-curable sealing resin is 40 μm or less, and is 2.5 times or less the distance between adjacent extraction electrodes. Liquid crystal panel manufacturing method. 3. A glass substrate having an extraction electrode formed of a metal thin film and a glass substrate having a light-shielding film formed of a metal thin film around the display region. A mold sealing resin is applied, and a predetermined amount of a liquid crystal material is further dropped on a display area of one of the substrates. Then, the two substrates are bonded to each other, and the sealing resin is irradiated by irradiating ultraviolet rays from both sides of the two substrates. A method for manufacturing a liquid crystal panel, comprising a step of bonding a glass substrate to be cured. 4. The extraction electrode according to claim 3, wherein the width of the extraction electrode in the region overlapping with the ultraviolet-curable sealing resin is 40 μm or less, and 3.0 times or less the distance between adjacent extraction electrodes. Liquid crystal panel manufacturing method. 5. A glass substrate having an extraction electrode formed of a metal thin film and a glass substrate having a resin light-shielding film containing a black pigment around the display region. A UV-curable seal resin is applied, and a predetermined amount of liquid crystal material is dropped on a display area of one of the substrates. Then, the two substrates are overlapped with each other, and ultraviolet rays are irradiated from a glass substrate having a metal extraction electrode. A method of manufacturing a liquid crystal panel, comprising a step of bonding a glass substrate to cure a sealing resin by performing the step. 6. The extraction electrode according to claim 5, wherein the width of the extraction electrode in a region overlapping with the ultraviolet-curable seal resin is 30 μm or less, and is 2.0 times or less the distance between adjacent extraction electrodes. Liquid crystal panel manufacturing method. 7. A glass substrate having an extraction electrode formed of a metal thin film and a glass substrate having a resin light-shielding film containing a black pigment around the display region. A UV-curable sealing resin is applied, and a predetermined amount of liquid crystal material is dropped on a display area of one of the substrates. Then, the two substrates are bonded to each other and irradiated with UV light from both sides of the two substrates to seal. A method for manufacturing a liquid crystal panel, comprising a glass substrate bonding step of curing a resin. 8. The method according to claim 7, wherein the width of the extraction electrode in a region overlapping with the ultraviolet-curable sealing resin is 30 μm or less, and is 2.5 times or less the distance between adjacent extraction electrodes. Liquid crystal panel manufacturing method.