JPH052428A - Liquid discharge amount controller - Google Patents

Abstract

PURPOSE:To accurately discharge a set amount of liquid by detecting the photodetecting value of a photodetecting part when the liquid is discharged from a discharge needle for detection of the discharging state of the liquid and at the same time controlling an adjustment mechanism based on the detecting result for control of the amount of the liquid discharged from the needle. CONSTITUTION:A liquid discharge amount controller detects the quantity of the light projected from a projecting fiber 12 and received by a photodetecting fiber 14 and judges the discharge amount of the liquid. When the liquid is discharged from a discharge needle 10, the quantity of light reaching the fiber 14 varies. Then the photodetecting value varies when the flow diameter changes in a discharge state. Thus the discharge amount of the liquid is known by the output of a detecting circuit 22. The diameter of the needle 10 is set at the prescribed value in accordance with the amount of liquid discharged from the needle 10. For instance, a piezo-element 24 is provided at the outer circumference of the tip of the needle 10 and the voltage applied to the element 24 is changed. So that the diameter of the needle 10 can be increased or decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid discharge amount control device.

[0002]

2. Description of the Related Art Although a display using liquid crystal is used in various display devices, the present applicant first found that, as a device for manufacturing a liquid crystal display in which a liquid crystal is sandwiched between two substrates, one of the substrates was placed on the other. An apparatus for pouring a fixed amount of liquid crystal and then bonding the other substrate is shown (Japanese Patent Application No. 3-57996). As a method of manufacturing a liquid crystal display, two substrates are bonded together at a predetermined interval in advance, the opening edges of the bonded substrates are immersed in the liquid crystal, and the liquid crystal is filled in the substrate by utilizing a capillary phenomenon ( Dipping method) is common. Compared to this method, the method described above has the advantages that impurities are not mixed into the liquid crystal, the liquid crystal is not wasted, and the manufacturing efficiency is high. However, according to this method, the amount of the liquid crystal to be supplied needs to be set accurately in order to fill the liquid crystal between the substrates in an appropriate amount.

As described above, the accurate setting of the amount of the liquid to be poured is not limited to the liquid crystal display manufacturing apparatus, and is the same when handling other various liquids. As a method of controlling the amount of liquid to be poured out, a method of controlling the pouring time by controlling the pouring time with a predetermined pouring pressure with a nozzle of a predetermined diameter, a method of detecting the liquid level and controlling the pouring amount, etc. There is.

[0004]

However, in the case where the amount of liquid to be poured out must be controlled extremely accurately as in the above-described liquid crystal display manufacturing apparatus, the conventional method provides sufficient accuracy. I can't. For example, even when liquid is pumped at a constant pressure to be poured out from a nozzle, the pouring pressure is controlled at a position apart from the actual pouring position of the nozzle, so the pouring conditions from the nozzle are delicate. It changes and a fixed amount is not always poured out. The same applies to the case where a fixed amount is detected on the liquid surface and the liquid is discharged, and the amount set in advance is not always accurately discharged due to the liquid adhering to the pipe wall of the transportation pipe.

Further, in the above-described liquid crystal display manufacturing apparatus, when pouring liquid crystal onto the substrate, the pouring nozzle is moved in a diagonal direction as shown in FIG. And the substrate (rectangular glass plate)
It is necessary to pour out more liquid in the central part than in the peripheral part, and it is necessary to perform delicate control by controlling the amount of liquid crystal that is poured out from the pouring needle as a whole. . Therefore, the present invention has been made in order to solve the above-mentioned problems and to enable accurate liquid pour-out control, and it is possible to accurately control the total amount of liquid to be pour out, and from the pouring needle. It is an object of the present invention to provide a liquid pouring amount control device capable of appropriately controlling the pouring amount of liquid.

[0006]

The present invention has the following constitution in order to achieve the above object. That is, a liquid is sent in contact with the liquid supply unit, and an outlet needle provided with an adjusting mechanism for expanding and contracting the diameter of the pipe to adjust the outflow amount of the liquid, and the liquid discharged from the outlet needle are intermediate. Then, the light emitting / receiving unit in which the light emitting unit and the light receiving unit are arranged at opposite positions on both sides, and the amount of light received by the light receiving unit when the liquid is ejected from the pouring needle are detected, and the liquid is poured out. And a control unit for detecting the state and controlling the adjusting mechanism based on the detection result to control the amount of liquid dispensed from the dispensing needle. Further, a piezo element operated by electrical control is used as an adjusting mechanism for expanding or contracting the pipe diameter of the dispensing needle.

[0007]

The liquid is delivered from the liquid supply unit to the dispensing needle, and the liquid is dispensed from the tip of the dispensing needle. The amount of light received by the light receiving unit changes depending on the amount of liquid ejected from the pouring needle, and by detecting the amount of light received by the light receiving unit, the pouring state of the liquid pouring from the pouring needle can be detected. Based on the detection result, the adjusting mechanism is controlled to adjust the pipe diameter of the dispensing needle to control the total amount of the liquid dispensed from the dispensing needle.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram of a main part that controls the liquid pouring amount by the liquid pouring amount control device according to the present invention. The liquid pouring amount control device of the present embodiment is characterized in that it detects and controls the state in which the liquid is actually ejected from the pouring needle.

That is, in FIG. 1, 10 is a dispensing needle for discharging a liquid, and 12 and 14 are a projecting optical fiber and a light receiving fiber installed on both sides of the dispensing needle 10, respectively. As shown in the figure, the projecting optical fiber 12 and the receiving optical fiber 14 are located slightly below the discharge end of the pouring needle 10, and the projecting end face 12a and the receiving end face 1
4a face each other. A rod lens 16 for projecting the projection light as a parallel light beam toward the light receiving end surface 14 is installed on the front side of the light projecting end surface 12a. Light emitting end face 12a
The optical system of the light receiving end face 14a and the rod lens 16 is
The parallel light flux emitted from the rod lens 16 is discharged from the needle 10
Set so that it crosses the discharge stream discharged from. Reference numeral 18 is a light source arranged on the rear surface of the projection optical fiber 12, 20 is a photodiode arranged on the light emitting end surface of the light receiving fiber 14, and 22 is a detection circuit for outputting a voltage analog output of a change in the light quantity when the liquid is being ejected. A halogen lamp, a laser diode or the like can be used as the light source 18.

The pouring needle 10 is set to have a predetermined pipe diameter according to the pouring amount of the liquid to be poured. Further, in the embodiment, the piezo element 24 is provided around the tip end side of the dispensing needle 10, and the diameter of the dispensing needle 10 can be expanded or reduced by changing the voltage applied to the piezo element 24. FIG. 2 shows a state in which the piezo element 24 is installed.
The liquid is transported to the pouring needle 10 at a predetermined pressure, but by controlling the piezo element 24, it is possible to adjust the pipe diameter of the pouring needle 10 and control the amount of liquid to be discharged.

The liquid pouring amount control device projects light from the projecting optical fiber 12 and receives light from the receiving optical fiber 14.
The amount of light received by is detected to determine the ejection amount.
When the liquid is ejected from the pouring needle 10, the amount of light reaching the light receiving fiber 14 changes, and when the flow diameter changes in the ejecting state, the amount of received light changes, so that the amount of pouring can be known from the output of the detection circuit 22. . FIG. 3 shows an output example in which the detection signal from the photodiode 20 is amplified. When the liquid is discharged from the discharge needle, the amount of light decreases and the output decreases. The range indicated by A in the figure is the time when the liquid is ejected, and the total amount of the liquid ejected can be regulated by integrating this ejection time. In this way, in the case of the liquid pouring amount control device, since the actually poured liquid is monitored to check the pouring amount, the liquid pouring amount can be specified as the actual pouring amount, It is characterized by extremely accurate and reliable pouring operation.

FIG. 4 shows an example in which the above-mentioned liquid pouring amount control device is applied to a liquid crystal display manufacturing device.
Hereinafter, an application example of this manufacturing apparatus will be described. The liquid crystal display manufacturing device shown here is for supplying liquid crystal and bonding substrates in a vacuum chamber.
The above-mentioned liquid pouring amount control device is used when liquid crystal is supplied to the lower substrate. The substrates to be bonded with the liquid crystal sandwiched therebetween are carried into the processing chamber 30 where the lower substrate and the upper substrate are separately bonded, and set on the work stages 32 and 34. An adhesive for bonding the upper substrate is previously applied to the outer peripheral portion of the lower substrate. Although the substrate loading operation is performed in a vacuum state, the substrate loading mechanism, the vacuum mechanism and the like are omitted in FIG.

When the substrates are bonded together, the mutual positions of the substrates need to be set accurately. Therefore, the work stage 32 that supports the lower substrate is supported by the XY stage 36 that can be rotationally adjusted along with the parallel movement in the plane, and the work stage 34 that supports the upper substrate is supported by the upper stage 38 that is tilted using a piezo unit. To support. The lower substrate and the upper substrate are aligned with each other by positioning using an optical fiber sensor. The XY stage 36 is supported by a support table 42 which is driven up and down while maintaining a vacuum state by a servo motor 40. After a predetermined amount of liquid crystal is poured onto the lower substrate as described later, the XY stage 36 rises and the lower substrate comes into contact with the upper substrate to bond the substrates. In an actual device, a heating unit for curing the adhesive, a vacuum system for evacuating the processing chamber 30, and the like are additionally provided, but the description thereof is omitted here.

Dispensing needle 10 and throwing optical fiber 1
2. The discharge parts such as the light receiving fiber 14 are set in the processing chamber 30 in the same arrangement as described above. Actually, the discharge part is attached to the end of the arm that rotates in the horizontal plane above the lower substrate, and the liquid crystal is poured out while rotating the arm (the arm is omitted in FIG. 4). Reference numeral 50 is a DD motor for rotating the arm. It should be noted that the piezo element for controlling the pipe diameter is attached to the tip of the dispensing needle 10 in the same manner as described above. 52 is an optical fiber 12 and a light receiving fiber 1
4 is a sensor driving unit including the above-described detection circuit 22 and the like, and 54 controls the piezo element 24 based on the output result of the detection circuit 22.
The control unit controls 0 to control the operation of the arm.

The proximal end side of the dispensing needle 10 communicates with the quantitative detection unit 56. The quantitative detection unit 56 is a chamber that detects and stores a predetermined amount of liquid crystal sent from the liquid crystal pot 58. The liquid crystal amount is detected using the liquid level sensor 60. The amount of liquid crystal contained in the quantitative detection unit 56 is controlled by opening / closing the opening / closing valve 62 based on the detection result of the liquid level sensor 60. Reference numeral 64 denotes a stirring motor that stirs the liquid crystal contained in the liquid crystal pot 58 to remove bubbles. Further, 66 is a needle 1 for pouring out the liquid crystal contained in the quantitative detection unit 56.
It is a pressurization control unit that applies a constant pressure to discharge from 0.

The operation of pouring out the liquid crystal in the above liquid crystal display manufacturing apparatus is performed as follows. First, the liquid crystal is agitated in the liquid crystal pot 58 to be defoamed, and then the on-off valve 62.
Is transported to the quantitative detection unit 56 through. In the quantitative detection unit 56, the liquid level sensor 60 calibrates the liquid crystal required for one pouring. The arm on which the dispensing needle 10 and the like are set is set on one outer edge portion of the substrate above the substrate, and as shown in FIG. 5, the DD motor 50 is driven to rotate in an arc shape toward the other diagonal. At the same time, the pressure control unit 66 controls the pressure in the quantitative detection unit 56 so that the liquid crystal is discharged from the discharge needle 10.

When the liquid crystal is poured onto the substrate, a large amount of the liquid crystal is poured out at the center of the substrate in consideration of the spread of the liquid crystal on the substrate as described above. Therefore, in the embodiment, the moving speed of the arm is slowed near the center of the substrate, and the pouring needle 10 is controlled so that a large amount of liquid crystal is poured near the center of the substrate. Figure 6
Shows the moving speed of the arm, and shows how the moving speed is reduced near the center of the substrate (portion B in the figure). The control unit 54 controls the DD motor 50 and controls the piezo element 24 based on the detection signals from the projecting optical fiber 12 and the receiving optical fiber 14 to control the liquid crystal pouring amount.

In this way, by controlling the liquid crystal pouring from the pouring needle 10 together with the movement control of the arm, the liquid crystal pouring amount can be set accurately, and the liquid crystal pouring operation to the substrate can be performed. Can be done very accurately. The liquid crystal used in a liquid crystal display has subtly different densities, viscosities, etc. depending on the product, so even if the pouring pressure etc. is set in advance to a certain amount, the actual amount of liquid crystal Is not always poured out. In this respect, according to the method of detecting the amount of liquid crystal actually discharged from the discharge needle and monitoring the total amount of discharge as in the present embodiment, it is possible to control as the amount actually discharged. Therefore, it is possible to eliminate an error in the amount of liquid to be dispensed due to the liquid crystal adhering to the tube wall, and to dispense a fixed amount of liquid with high accuracy. As a result, it is possible to prevent the generation of defective products by eliminating excess or deficiency of the amount of liquid crystal.

As is clear from the above operation method, the liquid for controlling the pouring is not limited to the liquid crystal, but can be applied to various liquids. Further, in the above example, the pouring operation was performed in vacuum, but it can be similarly applied to the use in normal atmosphere. Further, although the optical fiber is used to project and receive light in the above-described embodiment, the light projecting section and the light receiving section are not necessarily limited to the optical fiber, and a general projecting and receiving section may be used. Although the present invention has been variously described above with reference to the preferred embodiments, the present invention is not limited to these embodiments, and many modifications can be made without departing from the spirit of the invention. is there.

[0020]

As described above, according to the liquid pouring amount control device of the present invention, the liquid pouring amount is controlled by monitoring the pouring state of the liquid actually poured from the pouring needle. Therefore, it is possible to set the liquid pouring amount with extremely high accuracy. As a result, it is possible to prevent a defective product from being produced during the manufacture of the product.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a main configuration of a liquid pouring amount control device.

FIG. 2 is an explanatory diagram showing an attached state of a piezo element.

FIG. 3 is a graph showing an output example of a detection circuit when a liquid is poured.

FIG. 4 is an explanatory diagram showing an example in which a liquid pouring amount control device is attached to a liquid crystal display manufacturing apparatus.

FIG. 5 is an explanatory view showing the movement of the dispensing needle on the substrate.

FIG. 6 is an explanatory view showing the movement of the arm on the substrate.

[Explanation of symbols]

10 Dispensing needle 12 throw optical fiber 14 Light receiving fiber 16 rod lens 20 photodiode 22 Detection circuit 24 Piezo element 30 processing room 32, 34 work stages 36 XY stage 50 DD motor 52 Sensor drive unit 54 Control section 56 Quantitative detection unit 58 LCD pot 60 Liquid level sensor 66 Pressure control section

Claims (2)

[Claims] 1. A liquid is supplied by contacting a liquid supply section,
A dispensing needle provided with an adjusting mechanism for adjusting the outflow amount of the liquid by expanding and contracting the diameter of the pipe, and a light projecting portion and a light receiving portion at positions facing each other with the liquid discharged from the dispensing needle as an intermediate. And the amount of light received by the light receiving unit when liquid is ejected from the pouring needle to detect the pouring state of the liquid, and the adjusting mechanism based on the detection result. And a control unit for controlling the amount of liquid dispensed from the dispensing needle. 2. The liquid pouring amount control device according to claim 1, wherein a piezo element operated by electrical control is used as an adjusting mechanism for expanding or contracting the pipe diameter of the pouring needle. .