JP2000258777A - Manufacture of liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize sealing of a liquid crystal composition with a dripping method, to improve productivity of a liquid crystal display element and to reduce its cost by enabling a supporting means to vacuum-chuck substrates in laminating the substrates together under reduced pressure in order to prevent generation of air bubbles in the liquid crystal cell. SOLUTION: In this manufacturing method, at first the pressure in the pressure reducing device is kept comparative high, i.e., 103-104 Pa, the degree of the vacuum between supporting members 17, 18 and substrates 11, 12 is kept at 1-102 Pa to surely support the substrates 11, 12 with the supporting members 17, 18 and to align the both substrates 11, 12 and furthermore, a sealant 13 in almost half region of the array substrate 11 and the counter substrate 12 is laminated. Afterwards the air is evacuated from the gap between the array substrate 11 and the counter substrate 12 by reducing the pressure in the pressure reducing device to 1-102 Pa and subsequently the sealant 13 in the total region of the substrates 11, 12 is laminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a liquid crystal display device.

[0002]

2. Description of the Related Art In a liquid crystal display device in which a liquid crystal composition is sealed between a pair of substrates having electrodes, a method of sealing the liquid crystal composition is generally such that a pair of substrates is pasted together with a sealant. After assembling the cell, an injection method of injecting a liquid crystal composition from an injection port formed in a sealant and sealing the injection port with an adhesive or the like has been adopted.

[0003]

However, in the above-mentioned injection method, a substrate is bonded to form a liquid crystal cell.
Since the liquid crystal composition is injected from a narrow injection port, it takes a very long time from the hardening of the sealant to the completion of the injection of the liquid crystal composition, which has a problem that productivity is extremely poor. In addition, since the injection port is sealed with a sealing material after injection of the liquid crystal composition, a singular point is generated in the liquid crystal display element, which causes white spots and lowers the display quality. Further, there is also a problem that when the adhesiveness of the sealing material is poor, the sealing material is peeled off or bubbles are easily generated at the time of sealing.

For this reason, in recent years, a sealant having no injection port is arranged on a substrate, and a liquid crystal composition is dropped on a region surrounded by the sealant. The encapsulation of a liquid crystal composition by a dropping method of facing and bonding is also being studied.

However, in this dropping method, it is necessary to assemble under reduced pressure so that no air bubbles remain in the cells when the substrates are bonded. On the other hand, the opposing positioning operation of the substrate is generally performed by moving at least one of the substrates by vacuum suction using the holding means, but under reduced pressure in the dropping method, the substrate cannot be vacuum suctioned and the positioning cannot be performed. The problem has arisen and it has not been put to practical use.

Accordingly, the present invention has been made to solve the above-mentioned problems, and makes it possible to vacuum-adsorb a substrate by a holding means even under reduced pressure, and to realize a liquid crystal composition by a dropping method for shortening a time for sealing. An object of the present invention is to provide a method for manufacturing a liquid crystal display element.

[0007]

According to the present invention, as a means for solving the above-mentioned problems, the liquid crystal composition is opposed to a liquid crystal composition provided in a region surrounded by the sealant and the sealant under reduced pressure. In the method for manufacturing a liquid crystal display element in which two substrates are aligned and then bonded with the sealant, the pressure under reduced pressure is changed while the two substrates are bonded.

With this configuration, the present invention enables the liquid crystal by the dropping method which enables the substrate to be vacuum-sucked by the holding means even under reduced pressure when the substrates are bonded to each other, thereby achieving high productivity and good display quality. Encapsulation of the composition is feasible.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in FIGS. FIG. 1 is a configuration diagram showing a liquid crystal display element 10, for example, having a size of 150 mm.
A pixel electrode (not shown) on a × 200 mm glass substrate,
The array substrate 11 and the opposing substrate 12 provided with the opposing electrodes (not shown) are adhered to each other by a spacer (not shown) at a predetermined gap by a sealing agent 13 made of a thermosetting resin or the like. The liquid crystal composition 14 is sealed in the surrounding area.

Next, a method for manufacturing the liquid crystal display element 10 will be described. After a film forming technique and a photolithography technique are repeated on a glass substrate to form an array substrate 11 having pixel electrodes and a counter substrate 12 having counter electrodes, an alignment film (not shown) is applied and rubbed, respectively. According to the flow chart shown in FIG. 2, the array substrate 11 and the opposing substrate 12 are bonded together with the liquid crystal composition 14 interposed therebetween, and the liquid crystal display element 10 is assembled. First, in step 1, as shown in FIG. 3A, the array substrate 1 is kept at atmospheric pressure (10 ⁵ Pa).
A sealant 13 made of a thermosetting resin is applied around one pixel electrode by a dispenser or printing. Next, in step 2, as shown in FIG.
^{In 5} Pa), the liquid crystal composition 14 is dropped into a region surrounded by the sealant 13.

Next, in step 3, as shown in FIG. 3 (c), the array substrate 11 is vacuum-adsorbed to the lower holding member 17 in a decompression device (not shown), while the opposing substrate 12 is held in the upper holding member. The upper and lower holding members 17 and 18 are moved in a state where the substrates 11 and 12 are separated from each other by vacuum suction, and alignment is performed. At this time, the holding members 17 and 18 are
Pressure in the pressure reducing device should be 10
While the pressure is set relatively high at ³ to 10 ⁴ Pa, the pressure between the holding members 17 and 18 and the substrates 11 and 12 is reduced to 1/10 of the pressure.
And 1~10 ² Pa of ~ 1/100. Next, both substrates 1
At this time, the substrates 11 and 12 need to be vacuum-sucked by the holding members 17 and 18, at least the pressure between the holding members 17 and 18 and the substrates 11 and 12. The pressure inside the pressure reducing device is set relatively high so as to be higher. And the holding members 17, 1
The pressure in the decompression device is adjusted in two stages such that the pressure in the decompression device is set lower when the adsorption of the substrates 11 and 12 by the substrate 8 becomes unnecessary.

That is, first, in step 4, similarly to the position adjustment in step 3, the air pressure in the pressure reducing device is set to 10 ³ to 10 ^4.
While maintaining a relatively high Pa, the degree of vacuum between the holding members 17, 18 and the substrates 11, 12 is set to 1 to 10 ² Pa,
The counter substrate 12 is placed on the array substrate 11 for partial bonding in a state where the vacuum suction of the substrates 11 and 12 by the holding members 17 and 18 is ensured. At this time, as shown in FIG. 3D, the mechanical stopper 20 is inserted between the substrates 11 and 12 so that one side of the substrates 11 and 12 has a gap of about 1 mm. On the other hand, the sides facing this are the two substrates 11, 1
2 is in contact. Thereby, the array substrate 11
Then, the sealant 13 in an area about half of the counter substrate 12 is attached.

[0013] Then, in step 5, do a further evacuation of the vacuum device, to reduce the pressure to 1 to 10 ² Pa. As a result, air is exhausted from the gap supported by the mechanical stopper 20, and the gap between the substrates 11, 12 is set to a sufficient degree of vacuum that does not generate air bubbles in the liquid crystal cell. Note that the holding members 17 and 18 cannot vacuum-suck the substrates 11 and 12 due to the increase in the degree of vacuum in the decompression device. However, at this time, since about half of the area of both substrates is bonded with the sealant 13. Therefore, there is no possibility that a displacement occurs between the substrates 11 and 12.

Thereafter, after the gap between the substrates 11 and 12 is sufficiently exhausted, the mechanical stopper 20 is removed in step 6 and the sealant 13 in the entire area of the array substrate 11 and the counter substrate 12 is completely bonded. . Then step 7
When the substrates 11 and 12 are taken out into the atmosphere (10 ⁵ Pa), the substrate surface is uniformly pressed by the atmospheric pressure, and the gap between the substrates is uniformly maintained. Further, in Step 8, the sealant 1
3 is heat-cured to complete the liquid crystal display element 10. When a display test was performed using the liquid crystal display element 10 manufactured as described above, no display defect due to white spots was observed, and good display quality was obtained.

According to such a manufacturing method, the liquid crystal composition 14 can be sealed with a uniform sealing agent over the entire region, and a uniform gap can be obtained, so that the display quality of the liquid crystal display element 10 can be improved. Further, since the liquid crystal composition 14 is sealed by the dropping method, the manufacturing time can be remarkably reduced as compared with the conventional injection method, and the manufacturing cost can be reduced. Moreover,
Irrespective of the encapsulation process under reduced pressure, the array substrate 11 and the opposing substrate 12 can be aligned by reliably sucking and holding them by the holding means 17 and 18, thereby improving the alignment accuracy. By increasing the degree of vacuum between the substrates 11 and 12, the generation of bubbles in the liquid crystal cell can be reliably prevented, and the display quality of the liquid crystal display element 10 can be further improved.

The present invention is not limited to the above embodiment, but can be changed without departing from the spirit of the present invention. For example, the degree of vacuum in the decompression device in the manufacturing process can be arbitrarily set as necessary. Yes, it is only required that the holding means can adsorb the substrate at the time of alignment and the exhaust between the substrates can be reliably performed at the time of bonding. In addition, the pressure at the time of applying the sealant on the substrate or dropping the liquid crystal composition is not limited,
In the case where the subsequent alignment step and the like are performed in the same apparatus, the steps may be performed under the same reduced pressure as in the subsequent step. Further, the sealing agent is also arbitrary, such as being cured by ultraviolet irradiation. Further, the present invention is also applicable to a multi-process in which a plurality of liquid crystal display elements are simultaneously formed using a mother substrate having an area for a plurality of liquid crystal display elements.

[0017]

As described above, according to the present invention, the step of injecting the liquid crystal composition from the injection port, which takes a long time, becomes unnecessary, the manufacturing time of the liquid crystal display element can be shortened, and the cost can be reduced by improving the productivity. A reduction can be obtained. Moreover, while the substrate can be positioned with high precision, the generation of bubbles in the liquid crystal cell can be reliably prevented, and the display quality of the liquid crystal display element can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a liquid crystal display element according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a step of simulating a liquid crystal display element according to an embodiment of the present invention.

3A and 3B show a process of bonding an array substrate and a counter substrate according to an embodiment of the present invention, wherein FIG. 3A is an explanatory diagram showing application of a sealant, and FIG. 3B is an explanatory diagram showing dropping of a liquid crystal composition. (C) is an explanatory view showing the alignment, (d) is an explanatory view showing the substrate in the middle of bonding, and (e) is an explanatory view showing the state in which the substrate is completely bonded.

[Description of Signs] 10 ... Liquid crystal display element 11 ... Array substrate 12 ... Counter substrate 13 ... Sealant 14 ... Liquid crystal composition 17 ... Lower holding member 18 ... Upper holding member 20 ... Mechanical stopper

Claims (5)

[Claims] At least one substrate is positioned under reduced pressure with two substrates facing each other via a sealant and a liquid crystal composition provided in a region surrounded by the sealant, and then bonded with the sealant. In the method for manufacturing a liquid crystal display element, the pressure under reduced pressure is changed while the two substrates are bonded to each other. 2. The method for manufacturing a liquid crystal display device according to claim 1, wherein at the time of positioning, the two substrates are vacuum-adsorbed by holding means, respectively, and are opposed to each other. 3. The pressure difference between the positioning of two substrates and the bonding of a part of the two substrates,
3. The liquid crystal display device according to claim 1, wherein an air pressure between a time when a part of the two substrates is bonded and a time when the whole surface of the two substrates is bonded is reduced. Manufacturing method. 4. The air pressure between the positioning of two substrates and the bonding of a part of the two substrates is 10 ⁴ to 1
4. The pressure according to claim 3, wherein the pressure is from 0 to ³ Pa, and a pressure between the time when a part of the two substrates is bonded and the time when the entire surfaces of the ^two substrates are bonded is 1 to 10 ² Pa. The manufacturing method of the liquid crystal display element described in. 5. The pressure under reduced pressure between the positioning of two substrates and the bonding of a part of the two substrates,
3. The method for manufacturing a liquid crystal display device according to claim 2, wherein the degree of vacuum of the holding means is set higher than the degree of vacuum.