JP3079394B2 - Method and apparatus for manufacturing liquid crystal display element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a liquid crystal display device, in particular, a ferroelectric liquid crystal display device.

[0002]

2. Description of the Related Art In general, in order to maintain the distance between substrates (hereinafter referred to as cell thickness) of a liquid crystal display element, a spacer such as glass fiber, alumina beads, plastic beads, silica beads, etc. is used by using a spin coating method, a spraying method or the like. Is present on the substrate.

On the other hand, in recent years, there has been a high demand for an increase in the area of a liquid crystal display element, and the importance of uniformity of the cell thickness has been emphasized. In order to achieve a uniform cell thickness, for example, a method similar to that of a spacer is used. An adhesive bead such as a spherical particle adhesive made of an epoxy resin is present on the substrate.

Among the above methods, the spraying method has been widely used in terms of mass productivity and difficulty for large substrates. This spraying method is to spray a fine particle of spacers or adhesive beads in a volatile dispersion medium such as alcohol or chlorofluorocarbon on a substrate using a spray in which a volatile dispersion is fixed at a certain ratio, and then sprayed onto the substrate. In this method, only the spacer and the adhesive bead are present on the substrate by evaporating the volatile dispersion medium.

In the fine particle spraying step, a fixed amount of N2 gas is supplied via a mass flow controller to a two-fluid spray nozzle in which the liquid is taken in by a suction method.
Many methods have been adopted in which a volatile dispersion liquid in which fine particles are dispersed is sucked up from a container installed at a fixed position, and sprayed and dispersed.

In the above-mentioned spraying method, stirring is required to keep the particle concentration in the dispersion uniform, and the stirring device is equipped with a stirrer stirring or an ultrasonic stirring using an ultrasonic cleaning tank in the spraying apparatus. Was.

[0007]

However, in the above conventional spraying method, since the spray nozzle is fixed, the spray area is formed by spacers or adhesive beads sprayed from the tip of the spray nozzle. When spraying on a large substrate, it is necessary to keep the position of the spray nozzle away from the substrate because it is limited within the cone. As a disadvantage of such a method, the distance between the nozzle and the substrate is large, the adhesion efficiency of the particles is remarkably inferior, a large amount of spacers or adhesive beads are consumed,
The time required for spraying had to be long. Furthermore, since the spacer used in the ferroelectric liquid crystal display element is a fine particle of about 1 to 2 μm, if the spray nozzle is separated from the substrate, the time required for dropping cannot be ignored, which has been a major factor in reducing productivity. .
Furthermore, as described above, the spraying device has a circular area to be sprayed, and therefore, it is necessary to spray a wider area with respect to the size of the substrate to be sprayed, and it is difficult to reduce the size in terms of space. There was a disadvantage.

In order to improve the rigidity of the liquid crystal display element,
For ferroelectric liquid crystal display devices using adhesive beads,
In order to prevent the display quality of the liquid crystal display element from deteriorating due to the incorporation of fine particles such as the above-mentioned adhesive beads other than the liquid crystal substance, it is necessary to set a standard value for the arrangement density of the fine particles and manage them with a certain allowable width.

However, in the above-described spraying process using a two-fluid spray nozzle in which the liquid is taken in by the suction method, the height of the liquid level in the container is reduced due to the spraying and consumption of the dispersion, and the spray nozzle is sprayed. However, there is a disadvantage in that the amount of the dispersion liquid in which the fine particles are dispersed is reduced, and the density of the fine particles dispersed and disposed on the substrate is reduced, and the density of the fine particles is lower than the standard value.

[0010] Further, in the case of using the stirrer stirring or the ultrasonic stirring for stirring the dispersion liquid in the spraying method, there are the following disadvantages. (1) When Stirrer Stirring is Used The friction between the stirrer coated with Teflon and the adhesive beads, and the friction between the adhesive beads and the inner wall surface of the container cause the adhesive beads to aggregate and form a large mass. For this reason, when the adhesive beads are disposed on the substrate and the two substrates are bonded to each other, the gap between the substrates is caused by the cohesive adhesive beads. (2) In the case of performing ultrasonic stirring The high frequency vibration (20 to 50 KHz) of the ultrasonic waves causes the adhesive beads to collide with each other, the adhesive and the inner wall surface of the container, and the friction occurs, and the adhesive beads are aggregated. In this case, the agglomerated particles do not become as large as in the above (1), but since the flow of the liquid itself is not originally large, the adhesive beads are attracted to the inner wall surface of the container by static electricity, and as a result, the adhesive beads actually exist in the dispersion. The concentration of the particles is reduced, and a large difference occurs in the adhesive bead arrangement density within the substrate surface and between the substrates, resulting in instability.

[0011] By continuing to apply ultrasonic waves for a long period of time, the temperature of the volatile dispersion increases, and the amount of evaporation increases, so that the concentration of the adhesive beads in the dispersion gradually increases, and the dispersion is disposed on the substrate. The density of the adhesive beads to be used also increases.

An object of the present invention is to provide a method and an apparatus for manufacturing a liquid crystal display element having excellent display quality and impact resistance in view of the above-mentioned problems of the prior art.

[0013]

The above object is achieved by the present invention described below.

That is, a first aspect of the present invention is a method for manufacturing a liquid crystal display element in which a liquid crystal is sandwiched between two opposing substrates, wherein a spacer for maintaining a distance between the substrates and / or an adhesive for spot bonding the substrates are provided. In the fine particle spraying step of spraying the agent beads with a two-fluid spray nozzle in which the liquid is taken up by a suction method and disposing them on the substrate, for example, as shown in FIG. 2 , the spacer and / or the adhesive beads Is controlled so that the relative value (ΔH in the figure) of the height of the liquid level of the volatile dispersion liquid 60 in which is dispersed and the height of the tip of the spraying nozzle 61 is constant or substantially constant. In a method for manufacturing a liquid crystal display element, further, in a device for performing the above-described fine particle scattering step, for example, the volatile dispersion 6
Photoelectric sensor for detecting liquid level 0, and volatile dispersion 6
A liquid crystal display element having a means for controlling the level of the volatile dispersion 60, comprising a drive unit 64 and a control unit 69 of an elevator for moving the container 62 storing 0 in the vertical direction. Device.

According to the first aspect of the present invention, a decrease in the arrangement density of the fine particles due to the consumption of the volatile dispersion is prevented, and particularly when the fine particles are adhesive beads, the decrease in the arrangement density of the adhesive beads is prevented. As a result, it is possible to manufacture a liquid crystal display element without a drop in impact resistance.

Hereinafter, the first embodiment of the present invention will be specifically described with reference to the drawings.

[0017] FIG. 2 is a diagram schematically showing an example of a manufacturing apparatus of the present invention the first liquid crystal display device.

In the figure, reference numeral 61 denotes a two-fluid spray nozzle in which the liquid is taken in by a suction method, 66 denotes fine particles (for example, a spacer material or an adhesive bead), and 62 denotes a volatile dispersion liquid 60 in which the fine particles 66 are dispersed (for example, IPA). 63 is a means for detecting the liquid level in the container 62, a photoelectric sensor having a fixed height, and 64 is a container
A driving unit of an elevator, which is a means for keeping the liquid level in the inside constant; 65, a substrate on which fine particles 66 are dispersed and arranged; 67, a pipe for sending N ₂ gas to a two-fluid spray nozzle 61; A pipe for sending the volatile dispersion 60 to 61, a control unit of an elevator, 69 is a mass flow controller for supplying a fixed amount of N ₂ gas to the two-fluid spray nozzle 61.

In the above apparatus, the two-fluid spray nozzle 61 takes in the volatile dispersion 60 in the container 62 at a negative pressure generated by the supply of the N ₂ gas and sprays it toward the substrate 65. With the spraying of the liquid, the liquid level in the container 62 gradually decreases. However, the liquid level in the container 62 is always detected by the photoelectric sensor 63, and the height of the liquid level in the container 62 is corrected and controlled by the elevator. Thus, the difference Δ between the height (H ₂ ) of the tip of the two-fluid spray nozzle 61 and the height (H ₁ ) of the liquid surface of the dispersion liquid is obtained.
H = H ₂ −H ₁ is constant with an accuracy of ± １ ／ d (usually, H ₂ > H ₁ , and d is the distance between a pair of photoelectric sensors). Therefore, even if the liquid level in the container 62 decreases, the amount of the volatile dispersion liquid 60 sucked up by the two-fluid spray nozzle 61 does not decrease, and the arrangement density of the fine particles 66 on the substrate 65 does not decrease.

The first aspect of the present invention is not limited to the above configuration. For example, as a means for detecting the liquid level of the volatile dispersion liquid 60, a float sensor, an ultrasonic sensor, or the like may be used in addition to the photoelectric sensor. A ball screw, a nut, or the like can be used as a means for moving the container 62 up and down.

Further, in the apparatus shown in FIG. 2 , by moving the container 62 storing the volatile dispersion 60 up and down, the liquid level of the volatile dispersion 60 and the height of the tip of the spray nozzle 61 are relatively adjusted. However, the same operation may be performed by supplying an amount corresponding to the consumed volatile dispersion 60 into the container 62 from another supply system.

Next, the second embodiment of the present invention will be described.

According to a second aspect of the present invention, there is provided a method for manufacturing a liquid crystal display device comprising a liquid crystal sandwiched between two opposing substrates.
When disposing the adhesive beads for point-adhering the substrate on the substrate by a spraying method, at least a volatile dispersion liquid in which the adhesive beads are dispersed is stirred by low-frequency vibration. The present invention further provides an apparatus for manufacturing a liquid crystal display element, which comprises means for stirring the volatile dispersion by low-frequency vibration. According to the second aspect of the present invention, a low frequency vibration stirring system of, for example, 10 to 50 Hz is mounted on the spraying device, and the adhesive bead dispersion liquid is stirred without aggregating the adhesive beads. It is possible to keep the particle concentration in the liquid uniform.

Further, there is no need to insert a stirring blade, a stirrer or the like into the liquid, and the dispersion is excellent in dust-freeness.

Hereinafter, the second embodiment of the present invention will be specifically described with reference to the drawings.

FIG . 10 is a drawing of a low frequency vibration stirring system that best illustrates the second feature of the present invention . In FIG . 10 , reference numeral 101 denotes a volatile dispersion obtained by dispersing adhesive beads in a volatile dispersion medium; Is a Teflon tube connected to a spray nozzle for spraying the dispersion liquid 101;
Vibration generator (manufactured by IMV Co., Ltd.) that gives vibration to 3, 1
05 is the oscillation amplifier. Further, an acceleration pickup 106 for detecting acceleration of vibration is provided above the container 103.
Is installed, and an automatic vibration controller 107 for controlling vibration
It is connected to the.

The automatic vibration controller 107 can control the vibration frequency, displacement, and acceleration.
５０50 Hz) and the acceleration was set to the adhesive bead dispersion liquid 101.
(0.2-1.5G) enough to keep the particle concentration uniform
And If the acceleration value is set to a value higher than that, the dispersion liquid 101 splashes, and the droplets adhere to the upper part of the inner wall surface of the container, the lid of the container, etc., and when dried, it is not preferable because it causes the aggregation of adhesive beads.

When the spraying is continued, the amount of the dispersion liquid is reduced and the weight is reduced, so that the acceleration of the vibration is increased. In this case, the acceleration is detected by the acceleration pickup 106 installed on the upper portion of the container 103, and the acceleration is detected. Automatic vibration controller 1
Since the feedback is performed at 07, the acceleration is always kept constant regardless of the liquid weight.

In this way, the adhesive bead dispersion liquid is vibrated and agitated with a constant low frequency and acceleration vibration.

The second aspect of the present invention is not limited to the above configuration. For example, by supplying an amount corresponding to the consumed volatile dispersion liquid 101 to the container 103 from another supply system, The amount of the volatile dispersion liquid 101 may be kept constant, and the acceleration of vibration may be kept constant.

In the production method of the liquid crystal display device of the present invention, a ferroelectric liquid crystal as a liquid crystal sandwiched between the substrate
Can be preferably used .

As the ferroelectric liquid crystal used in the present invention , a liquid crystal having a chiral smectic phase can be used. Specifically, a chiral smectic C phase (Sm
C ^* ), H phase (SmH ^* ), I phase (SmI ^* ), K phase (Sm
mK ^* ) or G-phase (SmG ^* ) liquid crystal can be used. As a particularly preferred ferroelectric liquid crystal, a liquid crystal exhibiting a cholesteric phase on the high temperature side can be used. For example, a pyrimidine-based mixed liquid crystal can be used.

FIG . 1 is a sectional view showing an example of a ferroelectric liquid crystal display device manufactured by the manufacturing method of the present invention . Reference numerals 31 and 31 'denote a pair of substrates made of a glass plate, a plastic plate, or the like, and 32 denotes a transparent electrode group formed in a predetermined pattern such as a strip pattern (for example, a scanning voltage application electrode group in a matrix electrode structure). , 32 ′ are transparent electrode groups in the direction crossing 32 (for example, a signal voltage application electrode group in a matrix electrode structure), 33, 33 ′ are insulating films formed by sputtering or the like, and 34, 34. 'Is an alignment film formed by, for example, a printing method, 35 is a sealing material for sealing the pair of substrates 31, 31', 36 is a spacer for maintaining the cell thickness, and 37 is a pair of substrates 31, 31 '. Is an adhesive bead for point bonding, and 38 is a pair of substrates 31, 31 '.
It is a ferroelectric liquid crystal sandwiched between. Numeral 30 indicates these cell structures.

[0034]

Next, the present invention will be described with reference to examples.

Embodiment 1 This embodiment relates to the first embodiment of the present invention, in which a fine particle scattering step in the process of manufacturing a liquid crystal display element as shown in FIG. 1 is performed using an apparatus as shown in FIG. It is.

First, ITO stripe electrodes 32, 3 were formed on two glass substrates 31, 31 'each having a thickness of 1.1 mm.
2 ′ is formed thereon, and Ta ₂ O ₅ is formed thereon by sputtering.
After forming the films 33 and 33 'to a thickness of 1000 °, the LQ
1802 (Polyimide alignment film 34, 3 manufactured by Hitachi Chemical Co., Ltd.)
4 ′) was applied by a flexographic printing method, baked at a temperature of 270 ° C. for 1 hour, formed into a thickness of 300 °, and then subjected to a rubbing treatment. The sealing material 35 (manufactured by Mitsui Toatsu Chemicals Co., Ltd., trade name: Struct Bond XN-21-F) is formed on the first substrate 31 obtained as described above by screen printing.
Is printed, and an apparatus as shown in FIG.
To perform a fine particle scattering step.

Specifically, the allowable value of the disposition density of the adhesive beads is set at 8 from the viewpoint of imparting impact resistance and preventing deterioration of display quality.
It was determined as 0 ± 5 / mm ² . Conventionally, the spraying was performed without controlling the fluctuation width of the relative value ΔH between the height of the tip of the spray nozzle 61 and the liquid level of the volatile dispersion liquid 60,
When ΔH = 5 mm is initially set and the adhesive bead is sprayed 20 times, as shown in FIGS. 3 , 4 , and 5 , as the number of sprays increases, ΔH increases, the consumption of the dispersion per one time decreases,
There was a reduction in the density of the adhesive beads. Here, the density of the adhesive beads and the impact resistance value of the panel have a relationship as shown in FIG. 6 , but when examining the impact resistance value of the 20 panels on which the adhesive beads were sprayed, The panels sprayed at the 19th and 20th times were below the impact resistance standard value and were defective. On the other hand, in the system shown in FIG.
m and the adhesive beads were sprayed 20 times .
As described in 7 , 8 , and 9 , the above-mentioned phenomenon accompanying the increase in the number of times of spraying did not occur, and none of the 20 panels had a defective product having a value lower than the standard value of impact resistance.

Example 2 This example relates to the second aspect of the present invention, and shows a diagram at the time of the fine particle scattering step .
The liquid crystal display element was produced by using the apparatus shown in FIG. 10 and spraying the volatile dispersion on a substrate while stirring with low frequency vibration.

10 g of epoxy adhesive beads (trade name: “Trepearl”, manufactured by Toray Industries, Ltd., 5.5 μm in diameter: 5.5 μm) were dispersed in 500 cc of Freon 113 using the spraying apparatus shown in FIG .
Was dispersed on the first substrate on which the sealing material was formed by a screen printing method. Further, the second substrate, on which SiO ₂ particles having a diameter of 2 μm had already been disposed, and the first substrate were bonded and pressed. FIG. 11 shows the results obtained by preparing 46 sets of the above cells and measuring the change in the average arrangement density of the adhesive beads for each cell for every 5 sets. In addition, in the 46 sets of cells, there was no substrate spacing defect caused by the aggregation of the adhesive beads.

As a comparative example, the dispersion 101 was stirred by ultrasonic stirring, and the density change of the adhesive beads in 40 sets of cells prepared under the same conditions as in the above example was measured for every 5 sets . FIG . In the figure, the crosses indicate cells in which the substrate spacing failure occurred due to the aggregation of the adhesive beads, and the number of the crosses indicates the number of defective portions.

The adhesive bead dispersion by the apparatus shown in the present invention the second 10, the liquid volume constant in the low frequency regardless, is vibrated at an acceleration, without causing agglomeration of particles, uniform grain Since the concentration can be maintained, a liquid crystal display device having a small change in the arrangement density can be manufactured.

[0042]

As described above, the present invention has the following effects. ( 1 ) According to the first method and apparatus for manufacturing a liquid crystal display element of the present invention, the difference ΔH between the height of the tip of the two-fluid spray nozzle and the level of the volatile dispersion is always or substantially constant. By controlling, the two-fluid spray nozzle sucks up and the amount of the volatile dispersion to be sprayed per spray is always or almost constant, and the disposition density of the fine particles decreases as the number of sprays increases. In particular, in the case of a ferroelectric liquid crystal display device, it is possible to prevent a decrease in the impact resistance of the liquid crystal display device due to a reduction in the arrangement density of the adhesive beads. ( 2 ) According to the second method and apparatus for manufacturing a liquid crystal display device of the present invention, when disposing the adhesive beads on the substrate by the spraying method, the volatile dispersion is vibrated by low-frequency vibration. By agitation, (a) prevention of agglomeration of the adhesive beads (b) prevention of change in the particle concentration in the liquid due to adhesion of the adhesive beads to the inner wall surface of the container (c) uniformity of the concentration of the adhesive bead particles in the dispersion liquid And an element having a small change in the density of the adhesive beads can be manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a ferroelectric liquid crystal display device manufactured according to the present invention .

An example of FIG. 2 manufacturing apparatus of the present invention the first liquid crystal display element is a diagram schematically showing.

FIG. 3 is a graph showing the relationship between the number of sprayings and ΔH in a conventional example.

FIG. 4 is a graph showing the relationship between the number of applications and the amount of dispersion consumed per application in a conventional example.

FIG. 5 is a graph showing the relationship between the number of sprays and the density of adhesive beads provided in a conventional example.

FIG. 6 is a graph showing a relationship between an adhesive bead disposition density and an impact resistance value of a panel.

FIG. 7 is a graph showing the relationship between the number of sprayings and ΔH in the first embodiment of the present invention.

FIG. 8 is a graph showing the relationship between the number of applications and the amount of dispersion liquid consumed per application in the first embodiment of the present invention.

FIG. 9 is a graph showing the relationship between the number of times of spraying and the density of adhesive beads provided in the first embodiment of the present invention.

FIG. 10 is a diagram schematically showing an example of the second apparatus for manufacturing a liquid crystal display element of the present invention.

FIG. 11 is a graph showing an average arrangement density of adhesive beads of 46 sets of cells manufactured in Example 2 according to the second embodiment of the present invention.

FIG. 12 is a graph showing an average arrangement density of adhesive beads of 40 sets of cells manufactured by a conventional method.

[Explanation of symbols]

 Reference Signs List 30 Cell structure 31, 31 'Substrate 32, 32' Transparent electrode group 33, 33 'Insulating film 34, 34' Alignment film 35 Sealing material 36 Spacer 37 Adhesive bead 38 Ferroelectric liquid crystal 60 Volatile dispersion 61 Spray nozzle 62 Container 63 Photoelectric Sensor 64 Elevator Drive 65 Substrate 66 Fine Particle 67, 68 Pipe 69 Elevator Control 70 Mass Flow Controller 101 Volatile Dispersion 102 Teflon Tube 103 Container 104 Vibration Generator 105 Oscillation Amplifier 106 Acceleration Pickup 107 Automatic Vibration Control vessel

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kimio Takahashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-64-76031 (JP, A) JP-A-59 -143125 (JP, A) JP-A-2-280124 (JP, A) JP-A-4-313728 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1339 G02F 1/13 101

Claims (4)

(57) [Claims] In a method for manufacturing a liquid crystal display element comprising a liquid crystal sandwiched between two opposing substrates, a liquid crystal is taken in by a spacer for maintaining a distance between the substrates and / or an adhesive bead for point bonding the substrates. During the fine particle spraying step of spraying with a two-fluid spray nozzle that is a suction system and disposing on the substrate, the height of the volatile dispersion liquid in which the spacers and / or the adhesive beads are dispersed, A method for manufacturing a liquid crystal display element, wherein a height of a tip of a nozzle for spraying is controlled to be relatively constant or substantially constant. 2. A liquid crystal display device manufacturing method according to claim 1 , wherein said fine particle scattering step includes a means for controlling a liquid level of said volatile dispersion liquid. Display device manufacturing equipment. 3. A method of manufacturing a liquid crystal display device comprising a liquid crystal sandwiched between two opposing substrates, wherein an adhesive bead for point-adhering the substrates is provided on the substrates by a spraying method. And a method of manufacturing a liquid crystal display device, comprising stirring a volatile dispersion in which at least the adhesive beads are dispersed by low-frequency vibration. 4. An apparatus for manufacturing a liquid crystal display element used in the method for manufacturing a liquid crystal display element according to claim 3 , further comprising means for stirring the volatile dispersion by low frequency vibration. For manufacturing liquid crystal display elements.