JPH03246514A - Method for supplying liquid crystal to substrate for liquid crystal display element - Google Patents

Abstract

PURPOSE:To accurately control the amount of supplied liquid crystal in a small unit and to supply a proper amount of liquid crystal which is neither excessive nor deficient onto a substrate by dripping the liquid crystal on the substrate with a liquid crystal supply nozzle which discharges the liquid crystal by the vibration of the piezoelectric element. CONSTITUTION:The liquid crystal supply nozzle 10 which discharges a specific amount of liquid crystal supplied from a liquid crystal tank 320 by the vibration of the piezoelectric element 18 is used to drip the liquid crystal discharged from this nozzle on the substrate 1 plural times. The amount of liquid crystal from the liquid crystal supply nozzle 10 is therefore determined by the area and amplitude of the vibration part of the nozzle 10 and the amplitude of this vibration part is controlled with a voltage applied to the piezoelectric element 18, so the amount of liquid crystal dripped from the nozzle 10 each time is controllable to an extremely small amount. Consequently, the amount of liquid crystal which is supplied can accurately be controlled in small units and the liquid crystal can be supplied onto the substrate by the proper amount which is neither excessive nor deficient.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for supplying liquid crystal to a substrate for a liquid crystal display element.

[Conventional technology]

Conventionally, in a liquid crystal display element, after a liquid crystal cell is assembled by bonding a pair of substrates on which transparent electrodes, an alignment film, etc. are formed using a sealing material, the liquid crystal is injected through a liquid crystal injection port previously formed in a part of the sealing material. It is manufactured by injecting liquid crystal into the cell using a vacuum injection method, and then sealing the liquid crystal injection port.

However, with this manufacturing method, when injecting liquid crystal into the cell using the vacuum injection method, the side surface of the cell where the liquid crystal injection port is formed must be immersed in a liquid crystal dish, which may cause liquid crystal to adhere to the side surface of the cell and cause the liquid crystal to be injected into the cell. In addition, after the liquid crystal is injected, it is necessary to clean the liquid crystal adhering to the side surface of the cell and seal the liquid crystal injection port, which makes manufacturing the liquid crystal display element troublesome.

For this reason, recently, a manufacturing method has been devised in which before assembling the cell, an appropriate amount of liquid crystal is supplied onto one of the substrates, and then the opposite substrate is polymerized and bonded in vacuum to assemble the cell. According to this method, a liquid crystal display element can be efficiently manufactured without wasting liquid crystal.

When manufacturing liquid crystal display elements using this method, conventionally, a frame-shaped sealing material (thermosetting adhesive such as epoxy resin) was printed on the surface of the substrate supplying the liquid crystal, and the sealing material was semi-cured. Thereafter, the liquid crystal is dripped into the liquid crystal enclosed area of the substrate surrounded by the frame-shaped sealing material using an air extrusion type dispenser that extrudes the liquid crystal using air pressure.

Note that the liquid crystal dropwise supplied onto the substrate is applied to the entire area surrounded by the sealing material by overlapping this substrate and another substrate and applying pressure so that the interval between them becomes a predetermined cell gap. It is pushed out. Further, the pair of polymerized substrates is bonded together by curing the sealing material after applying pressure.

[Invention or problem to be solved]

However, the conventional liquid crystal supply method in which liquid crystal is dropped onto a substrate using an air extrusion dispenser has a problem in that the amount of liquid crystal dropped per dispenser is large, and the amount of liquid crystal supplied cannot be precisely controlled.

That is, the above-mentioned air extrusion type dispensers include those that extrude the liquid crystal using only air pressure, and those that extrude the liquid crystal by providing a needle in the extrusion hole of the liquid crystal and moving the needle up and down with a solenoid. Although a dispenser equipped with a needle is capable of dispensing a relatively small amount, the amount of liquid crystal dispensed each time is still at least 1 mg ± 10.
It is about %.

The liquid crystal is supplied to the substrate the required number of times (for example, once to several times in the case of a substrate used for a small screen liquid crystal display element), depending on the area of the liquid crystal sealing area of the substrate and the cell gap of the cells assembled after supplying the liquid crystal. ) However, in the conventional liquid crystal supply method described above, even if a dispenser equipped with a needle is used, the amount of liquid crystal dropped per time is about 1 mg ± 10% as described above. Because it is large,
The amount of liquid crystal supplied to the substrate can only be controlled in large units of 1 mg±10%.

For this reason, with conventional liquid crystal supply methods, the amount of liquid crystal supplied may be insufficient, creating gaps in the assembled cell, or the amount of liquid crystal supplied may be too large, causing the liquid crystal to overcome the sealing material during cell assembly. Sometimes I put it away.

Moreover, in the above-mentioned conventional liquid crystal supply method, the amount of liquid crystal dropped per time is large, and the droplets of liquid crystal dropped on the substrate are also large. However, there is a problem in that the droplets overcome the surface tension and spread over a wide range and touch the sealing material, thereby deteriorating the liquid crystal supplied on the substrate. This is because the sealant is in an uncured (semi-cured) state when liquid crystal is supplied onto the substrate, and liquid crystal is applied to the uncured sealant for a long period of time (from the time liquid crystal is supplied onto the substrate to when the pair of substrates If the liquid crystal is left in contact with the liquid crystal (for a period of time after polymerization and pressurization until the sealing material 2 is cured), the quality of the liquid crystal will change due to the introduction of impurities from the sealing material and decomposition of the liquid crystal, and its properties will deteriorate.

The present invention was made in view of the above-mentioned circumstances, and its purpose is to precisely control the supply amount of liquid crystal in small units to supply an appropriate amount of liquid crystal on a substrate. Supplying liquid crystal to a substrate for a liquid crystal display element, which can also prevent liquid crystal from deteriorating due to contact with uncured sealant by almost eliminating the flow and spreading of liquid crystal dropped onto the substrate. The purpose is to provide a method.

[Means to solve the problem]

The method of supplying liquid crystal to a substrate for a liquid crystal display element of the present invention uses a liquid crystal supply nozzle that discharges a predetermined amount of liquid crystal supplied from a liquid crystal tank by vibration of a piezoelectric element, and a plurality of liquid crystals discharged from this nozzle are placed on a substrate. It is characterized by being dropped multiple times.

[Effect]

That is, in the present invention, liquid crystal is dropped onto a substrate by a liquid crystal supply nozzle that discharges liquid crystal by vibration of a piezoelectric element, and the amount of liquid crystal discharged from this liquid crystal supply nozzle is determined by the area of the vibrating part of the nozzle. Since the amplitude of this vibrating portion can be controlled by the voltage applied to the piezoelectric element, the amount of liquid crystal dropped from the nozzle per drop can be made extremely small. Therefore, according to the present invention, it is possible to accurately control the supply amount of liquid crystal in small units and supply an appropriate amount of liquid crystal on the substrate without excess or deficiency. Further, according to the present invention, since the liquid crystal droplets dropped on the substrate are small, the droplets dropped on the substrate maintain a droplet state due to their surface tension. By shifting the positions of the drops so that they do not stick together and forming large drops, the liquid crystal that has been dropped onto the substrate will hardly flow and spread, and it will also prevent deterioration of the liquid crystal caused by the liquid crystal touching uncured sealant. be able to.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 8.

FIG. 1 shows the state of supplying liquid crystal onto a substrate according to this embodiment. In the figure, 1 is a transparent substrate for a liquid crystal display element made of a glass plate, etc., and one surface of this substrate is coated with ITO, etc. A transparent electrode and an alignment film (both not shown) are formed, and a frame-shaped sealing material 2 made of a thermosetting adhesive is printed surrounding the liquid crystal enclosed area. Note that this sealing material 2 is semi-cured at a temperature lower than its curing temperature to such a degree that when the substrate 1 and another substrate are stacked and pressurized, the sealing material 2 is crushed and deformed by the pressure. . Reference numeral 10 denotes a liquid crystal supply nozzle that supplies liquid crystal a to the liquid crystal sealed area surrounded by the frame-shaped sealing material 2 of the substrate 1.

As shown in FIGS. 3 to 5, this liquid crystal supply nozzle 10 has a piezoelectric element 18 provided on one side of a vertical box-shaped hollow nozzle body 11, and inside the nozzle body 11 is a vertical partition plate. It is divided into a front side and a back side by 11b, the space on the back side is a liquid crystal reservoir chamber 12, and the space on the front side is a liquid crystal discharge chamber 13. A liquid crystal supply port 14 communicating with the liquid crystal reservoir 12 is provided at the upper end of the back surface of the nozzle body 11, and a liquid crystal supply port 14 communicating with the liquid crystal reservoir 12 is provided at the upper and lower ends of the partition plate 11b. Liquid crystal inlets 15 and 16 are provided which communicate with the upper end of the liquid crystal discharge chamber 13. Among the liquid crystal suction ports 15 and 16, the suction port 15 on the upper end side is a large diameter hole, and the auxiliary suction port 16 is a small diameter hole. Further, at the bottom of the liquid crystal discharge chamber 13, a small diameter liquid crystal discharge port 17 that opens at the lower surface of the nozzle body 11 is provided. Furthermore, the front surface of the nozzle body 11, that is, the front plate of the liquid crystal discharge chamber 13, is a diaphragm 11 made of a thin metal plate.
c, and the piezoelectric element 18 is connected to this diaphragm 11c.
is glued to the outside surface of the The nozzle body 11 includes a back plate 11a in which a recessed portion that becomes the liquid crystal storage chamber 12 and the liquid crystal supply port 14 are formed, a recessed portion that becomes the liquid crystal discharge chamber 13, the liquid crystal suction port 15, 16, and the liquid crystal discharge port 14. A partition plate 11b in which an outlet 17 is formed and the diaphragm 11c are bonded together.

As shown in FIG. 1, the liquid crystal supply nozzle 10 is installed vertically above the substrate loading position with the liquid crystal discharge port 17 facing down. A liquid crystal supply hose 21 connected to the liquid crystal tank 20 is connected, and an oscillation circuit 19 is connected to the piezoelectric element 18.

The liquid crystal supply method of this embodiment uses the liquid crystal supply nozzle 10 as described above, and horizontally moves the substrate 1 carried under the liquid crystal supply nozzle 10 in one direction, and also horizontally moves the substrate 1 in one direction orthogonal to the moving direction of the substrate 1. The liquid crystal a is dripped onto the substrate 1 while the nozzle 10 is scanned in the direction shown in FIG.
This is done by vibrating the diaphragm 11C of No. 0 using the piezoelectric element 18.

6 to 8 show the liquid crystal discharging operation of the liquid crystal supply nozzle 10. FIG. 6 shows the initial state, and the nozzle 1
The liquid crystal reservoir chamber 12 and liquid crystal discharge chamber 13 of No. 0 are filled with liquid crystal a supplied from the liquid crystal tank 20. In addition,
The supply of liquid crystal a from the liquid crystal tank 20 into the nozzle 10 is as follows:
Either the liquid crystal tank 20 is installed at a higher position than the nozzle 10 and the liquid crystal a is supplied into the nozzle 10 by gravity, or the inside of the liquid crystal tank 20 is pressurized to a predetermined atmospheric pressure and the liquid crystal a is supplied with that pressure. This is done by supplying it into the nozzle 10. In addition, in this case, the liquid crystal tank 2 is in the liquid crystal a in the nozzle 10.
Since the supply pressure from 0 is applied, the liquid crystal a in the liquid crystal discharge chamber 13 is also pushed into the discharge port 17 by the pressure, but the liquid crystal a in the discharge port 17 is affected by the surface tension of its tip and the nozzle 1.
It stops at that position when the pressure of liquid crystal a in the liquid crystal tank 20 is balanced with the pressure of the liquid crystal a in the liquid crystal tank 20.
If the pressure is set to a level that does not push out the liquid crystal a in the discharge port 17, the liquid crystal a in the discharge port 17 will not leak out.

7 and 8 show the liquid crystal discharge state and the discharge stop state, in which a drive signal (voltage signal) of a predetermined frequency is applied to the piezoelectric element 18 from the oscillation circuit 19 with the nozzle 10 filled with liquid crystal a. When applied, the piezoelectric element 18 causes the vibration plate 11c of the nozzle 10 to vibrate. Then, when a voltage is applied to the piezoelectric element 18 and the vibration plate 11C swings inward as shown in FIG. 7, the volume of the liquid crystal discharge chamber 13 becomes smaller and its internal pressure increases.
With this pressure, the liquid crystal a in the liquid crystal discharge chamber 13 is discharged from the discharge port 17. The amount of liquid crystal a discharged is the same as the amount of decrease in the volume of liquid crystal discharge chamber 13, and the amount of liquid crystal a discharged from nozzle 10 per time is determined by the area and amplitude of diaphragm 11c.

The amplitude of this diaphragm 11c can be controlled by the amplitude (voltage) of the drive signal applied to the piezoelectric element 18.

In this example, the amount of liquid crystal a discharged from the nozzle 10 per time is Q, i, mg ~ 0, 0
It is controlled within the range of 1 rng.

Also, the vibration of the piezoelectric element 18 causes the diaphragm 11C to move to the eighth position.
When it is restored as shown in the figure, the volume of the liquid crystal discharge chamber 13 returns to its original value and its internal pressure becomes negative pressure, and the liquid crystal a in the liquid crystal reservoir chamber 12 is sucked into the liquid crystal discharge chamber 13 from the liquid crystal suction port 15° 16. At the same time, the liquid crystal a supplied from the liquid crystal tank 20 is replenished into the liquid crystal reservoir 12 from the liquid crystal replenishment port 14. At this time,
The liquid crystal a in the discharge port 17 is temporarily sucked toward the liquid crystal discharge chamber 13 as shown in FIG. 8 due to negative pressure in the liquid crystal discharge chamber 13; Since the liquid crystal a is also sucked in from the auxiliary suction port 16 at the lower end,
The liquid crystal a in the discharge port 17 does not completely enter the liquid crystal discharge chamber 13, so that some air is sucked into the lower end of the liquid crystal discharge chamber]3, and this air pocket prevents the next liquid crystal a from being discharged. is not impossible. In addition, the liquid crystal discharge chamber 1
When the discharge amount of liquid crystal a is sucked into the discharge port 17 and its internal pressure becomes the initial pressure (supply pressure from the liquid crystal tank 20), the liquid crystal a in the discharge port 17 reaches the initial state level shown in FIG. Return to

The following is a repetition of the above operation, and the liquid crystal supply nozzle 10
The liquid crystal a is ejected at a period corresponding to the frequency of the drive signal applied from the oscillation circuit 19 to the piezoelectric element 18.

Then, while horizontally moving the substrate 1 in one direction and scanningly moving the nozzle 10 in a direction perpendicular to the moving direction of the substrate 1, the liquid crystal a is ejected from the nozzle 10 at a predetermined period.
When the liquid crystal a is discharged from this nozzle 10,
As shown in FIGS. 1 and 2, the droplets are scattered over almost the entire area of the liquid crystal sealed area surrounded by the sealant 2 on the substrate 1. The number of drops of the liquid crystal a onto the substrate 1 may be determined according to the amount of liquid crystal a discharged from the nozzle 10 per time and the target supply amount to be supplied onto the substrate 1. Further, the dropping range of the liquid crystal a onto the substrate 1 is set to the range shown by the chain line in FIG. 2, avoiding the vicinity of the sealing material 2. This dropping range can be regulated by setting the scanning amplitude of the nozzle 10 and the liquid crystal ejection start and stop timing of the nozzle 10 to match an area that is somewhat smaller than the inner peripheral edge of the sealing material 2.

That is, the liquid crystal supply method described above uses a liquid crystal supply nozzle 10 whose negative side is constituted by a diaphragm 11a and a piezoelectric element 18 is attached to this diaphragm 11a, and causes the diaphragm 11a of this nozzle 10 to be vibrated by the piezoelectric element 18. By this, the liquid crystal a in the nozzle 10 is discharged and the liquid crystal tank 20
The liquid crystal a supplied from the nozzle 10 is sucked into the nozzle 10 a required number of times, and the liquid crystal a discharged from the nozzle 10 is transferred to the substrate 1.
The amount of liquid crystal a discharged from the liquid crystal supply nozzle 10 is determined by the area and amplitude of the diaphragm 11H, and the amplitude of the diaphragm 11a is determined by the voltage applied to the piezoelectric element 18. Since it can be controlled, the amount of liquid crystal a dropped each time from the nozzle 10 can be reduced to an extremely small amount (0.1 mg to 0.01+ng in the above example).
It can be done.

Therefore, according to this liquid crystal supply method, the supply amount of liquid crystal a can be supplied in much smaller units (1 in the case of the above example) than in the conventional supply method using an air extrusion type dispenser.
Since it is possible to control and supply an appropriate amount of liquid crystal a onto the substrate 1 with a unit of 1/10 to 1/100), the amount of liquid crystal supplied is There is no possibility that a gap will be created in the assembled cell due to an insufficient amount of liquid crystal, or that the liquid crystal will not exceed the sealing material during cell assembly due to an excessive supply of liquid crystal.

Furthermore, according to this liquid crystal supply method, since the droplets of liquid crystal a dropped onto the substrate 1 are small, the droplets dropped onto the substrate 1 maintain a droplet state due to their surface tension. If the drops are placed on the substrate 1 at different positions at intervals so that they do not stick together and form large drops, the liquid crystal a dropped on the substrate 1 will hardly flow and spread, and the liquid crystal will be placed on the uncured sealing material 2. Deterioration of the liquid crystal a due to contact with the liquid crystal a can also be prevented.

However, when the liquid crystal a supplied onto the substrate 1 is overlaid on this substrate 1 and another substrate (not shown) and pressurized so that the interval between them becomes a predetermined cell gap, the sealing material 2, the liquid crystal a touches the uncured (semi-cured) sealing material 2, but the pair of polymerized substrates immediately Since the liquid crystal a is bonded by curing the sealing material 2, the time that the liquid crystal a is in contact with the uncured sealing material 2 is extremely short, and therefore, during this time, the liquid crystal a is not affected to deteriorate it. There isn't.

In the above embodiment, in order to drop the liquid crystal a on the substrate 1, the substrate 1 is moved horizontally in one direction, and the nozzle 10 is moved in a direction perpendicular to the moving direction of the substrate 1.
This dotted dropping of the liquid crystal a may be performed by horizontally moving only the substrate 1 or the nozzle 10 back and forth, left and right, or by using a plurality of nozzles 10.
The nozzles 10 may be arranged in a direction intersecting the moving direction of the substrate 1, and the step may be performed while the substrate 1 is horizontally moved in one direction. Further, in the above embodiment, the liquid crystal display element 1
Although an example has been shown in which liquid crystal a is supplied to individual substrates 1, the present invention provides liquid crystal display for each element portion of a large substrate with an area equivalent to a plurality of liquid crystal display elements, which is separated into individual elements after cell assembly. It can also be applied to supply. Furthermore, in the above embodiment, the liquid crystal supply nozzle 10 has a white liquid crystal reservoir chamber 12 and a liquid crystal discharge chamber 13, but this liquid crystal supply nozzle only has one liquid crystal chamber whose negative side is constituted by a diaphragm. The liquid crystal chamber may be provided with a liquid crystal inlet and an outlet, and a piezoelectric element may be attached to the vibration plate.

〔Effect of the invention〕

In the present invention, the liquid crystal is dropped onto the substrate using a liquid crystal supply nozzle that discharges the liquid crystal by the vibration of a piezoelectric element. Therefore, the amount of liquid crystal dropped from the nozzle at one time can be reduced to an extremely small amount. Therefore, the supply amount of liquid crystal can be precisely controlled in small units to supply an appropriate amount of liquid crystal onto the substrate. Further, according to the present invention, since the liquid crystal droplets dropped on the substrate are small, the droplets dropped on the substrate maintain their droplet state due to their surface tension, so that the droplets stick to each other on the substrate. By shifting the position of the droplets so that they do not overlap and form large droplets, the liquid crystals dropped onto the substrate will hardly spread out and will prevent deterioration of the liquid crystals due to contact with uncured sealant. .

[Brief explanation of drawings]

FIGS. 1 to 8 show an embodiment of the present invention, in which FIG. 1 is a side view showing a state in which liquid crystal is supplied onto a substrate, FIG. 2 is a plan view of a substrate supplied with liquid crystal, Figure 3 is a front view of the liquid crystal supply nozzle, Figures 4 and 5 are the TV-T shown in Figure 3.
The sectional views taken along the V line and the V-V line, and FIGS. 6 to 8 are diagrams of the liquid crystal discharging operation of the liquid crystal supply nozzle. DESCRIPTION OF SYMBOLS 1...Substrate, 2...Sealing material, a...Liquid crystal, 1o
...Liquid crystal supply nozzle, 11...Nozzle body, llc
...Vibration plate, 12...Liquid crystal reservoir chamber, 13...Liquid crystal discharge chamber, 14...Liquid crystal supply port, 15.16...Liquid crystal suction port, 17...Liquid crystal discharge port, 1.・・Vibration plate, ・・Oscillation circuit, ・・LCD tank, ・・・LCD supply hose.

Claims (1)

[Claims] In a method of supplying liquid crystal to a liquid crystal enclosure area surrounded by a frame-shaped sealing material of a substrate for a liquid crystal display element, a liquid crystal supply nozzle that discharges a predetermined amount of liquid crystal supplied from a liquid crystal tank by vibration of a piezoelectric element is used. 1. A method for supplying liquid crystal to a substrate for a liquid crystal display element, comprising dropping liquid crystal discharged from the substrate onto the substrate multiple times.