HK1166289B - Method, apparatus and program for jetting liquid material - Google Patents

Description

Method, device and program for discharging liquid material

Technical Field

The present invention relates to a method, an apparatus, and a program for discharging a liquid material, in which a plunger sliding in a metering section communicating with a nozzle having a discharge port is moved by a desired amount to discharge the liquid material, and the operation of the plunger is controlled to repeatedly discharge a fixed amount of the liquid material without changing the discharge amount of the liquid material.

In the present specification, "flying" means that the liquid material is separated from the discharge port before contacting the object to be coated.

Background

There are currently discharge devices known as plunger pumps (or syringe pumps). Such a discharge device is often used in cases where a certain amount of liquid material needs to be discharged accurately in an ODF process or the like during the manufacture of a liquid crystal panel.

A plunger pump is a discharge device that discharges a liquid material from a discharge port by moving a plunger, which is in close contact with a metering section and moves forward and backward, and discharges the liquid material from the discharge port, and that discharges the liquid material with good accuracy by discharging a volume amount excluded by the movement of the plunger from the discharge port, and that discharges the liquid material by cutting the liquid material from the discharge port by rapidly stopping the plunger after moving the plunger forward and backward at a high speed.

In the plunger pump, since the plunger slides closely in the metering portion, a seal portion is often provided at the contact portion. Since the seal portion is a sliding portion, abrasion, deformation, and the like occur, and various adverse effects are exerted on the pump. For example, when it takes time, particles are generated to contaminate the liquid material, and must be replaced frequently. On the other hand, when the deformation is performed, the plunger moves regardless of whether the operation of the plunger is stopped, and the excess liquid material is discharged.

Therefore, various techniques for improving the sealing portion have been proposed up to now. For example, patent document 1 discloses a coating apparatus including a coating liquid transfer pump for guiding a coating liquid to a metal cap, wherein a sealing member used in the coating liquid transfer pump is a cap-shaped body formed of a flexible material, and a body portion (trunk portion) of the cap-shaped body covers a plunger in a state where an opening end portion of the cap-shaped body is fixed to an inner circumferential surface of a cylinder, and a U-shaped folded portion formed by folding back a gap between the cylinder and the plunger to a lower side seals the gap.

Further, patent document 2 discloses a dispenser including an O-ring provided in an annular groove portion formed at a distal end portion of a plunger and slidable along an inner wall surface of a syringe, the dispenser characterized in that: the annular groove is formed by a concave portion having a flat bottom wall in the whole region, is disposed at a side wall of the annular groove with a space, and is brought into contact with a side portion of the O-ring in accordance with press-fitting of the plunger, and is elastically displaced and thereby compressively deformed.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2006-281091

Patent document 2: japanese patent laid-open No. 2008-18351

Disclosure of Invention

(problems to be solved by the invention)

As described above, in the conventional technology, various improvements are applied to the plunger, and even with this technology, the accuracy of the discharge amount per time when the discharge is repeated a plurality of times cannot be improved. That is, when the plunger performs the discharge operation, the discharge amount varies from one operation to another, and therefore, the correct amount cannot be discharged, and the discharge amount fluctuates.

If the discharge amount varies, there is a problem in that, when the liquid material is discharged from a discharge port such as a nozzle, the liquid material is divided into a plurality of droplets and dispersed, or the liquid material is discharged without being dispersed from the nozzle.

Accordingly, an object of the present invention is to provide a method, an apparatus, and a program for discharging a liquid material, which can stabilize the droplet shape and the discharge state of the discharged liquid material and improve the discharge accuracy.

(means for solving the problems)

The present inventors assumed that the cause of the fluctuation in the discharge amount is caused by the difference between the frictional resistance acting on the sliding portion of the plunger at the start of the operation of the plunger and during the operation of the plunger, and verified whether this hypothesis is true. The frictional resistance between the plunger and the inner wall of the metering section includes: static friction generated when the plunger is shifted from a static state to an operating state, and dynamic friction generated during the operation of the plunger. Here, it is assumed that the frictional resistance applied to the plunger changes rapidly after the plunger starts to move by shifting from the static friction to the dynamic friction. In the verification, it was found that the movement of the plunger cannot be accurately tracked with respect to the movement of the drive source such as the motor or the air cylinder, the moving amount or speed of the plunger cannot be fixed, and the movement of the plunger becomes unstable (see fig. 2). Further, it has been found that the drive source itself is affected by the change in the frictional resistance of the plunger, and there is a problem that the operation is not always necessary for a command from the control device.

In the conventional technique for improving the seal portion of the plunger, these problems cannot be solved.

The present inventors have focused on the change of the plunger speed with time in the operation of the plunger, particularly in the discharge operation, and have found that the problem can be solved by improving the stability of the plunger operation at the time of starting the plunger operation, and thus have completed the present invention.

A first aspect of the present invention is a method for discharging a liquid material, the method including a metering unit for metering the liquid material, a discharge port communicating with one end of the metering unit, and a plunger slidably moving on an inner wall of the metering unit, the method including: a filling step of moving the plunger in a direction opposite to the discharge port to fill the liquid material into the metering section; and a discharging step of moving the plunger in the direction of the discharge port and then stopping the movement of the plunger, thereby causing the liquid material to fly and discharge from the discharge port; the method for discharging a liquid material is characterized by comprising a preliminary operation of moving the plunger without discharging the liquid material, and controlling the speed of the plunger in the discharging step to be constant.

In the method for discharging a liquid material according to the second aspect of the present invention, in the first aspect of the present invention, the preparatory operation is configured by: a first operation of moving the plunger by a predetermined distance S in a direction opposite to the discharge port; and a second operation of moving the plunger in a direction toward the discharge port by a distance equal to or equal to the distance S.

In the method for discharging a liquid material according to the third aspect of the present invention, in the second aspect of the present invention, the predetermined distance S is set to a distance that accelerates the plunger to a constant speed.

A method for discharging a liquid material according to a fourth aspect of the present invention is the method for discharging a liquid material according to the second or third aspect of the present invention, wherein the first operation and the second operation are repeated after the filling step until the discharging step is started.

A fifth aspect of the present invention is the method for discharging a liquid material according to any one of the second to fourth aspects of the present invention, wherein the first operation is to move the plunger under a condition that bubbles are not generated in the external gas sucked from the discharge port.

A sixth aspect of the present invention is the method for discharging a liquid material according to the second or second aspect, wherein the preliminary operation is an operation of gradually accelerating the plunger in a direction toward the discharge port.

A seventh aspect of the present invention is the method for discharging a liquid material according to any one of the first to sixth aspects of the present invention, wherein the preliminary operation and the discharging step are performed continuously.

A liquid material discharge device according to an eighth aspect of the present invention includes: a metering section for metering a liquid material; a discharge port communicated to one end of the metering portion; a plunger that slidably moves against an inner wall of the metering section; a drive source for driving the plunger; and a control device; the control device is capable of implementing the discharge method of any one of the first to seventh aspects of the invention.

A ninth aspect of the present invention provides an apparatus for applying a liquid material, comprising: a stage on which an object to be coated is placed; the discharge device of the eighth aspect of the present invention; and a relative movement mechanism for moving the discharge device and the stage relative to each other.

A program according to a tenth aspect of the present invention is characterized in that the control device in the liquid material discharge device is configured to perform the discharge method according to any one of the first to seventh aspects of the present invention, wherein the liquid material discharge device includes a metering portion for metering the liquid material, a discharge port communicating with one end of the metering portion, a plunger slidably moving against an inner wall of the metering portion, a drive source for driving the plunger, and the control device.

Further, the preparatory operation may be configured as follows: a first operation of moving the plunger by a predetermined distance S in a direction opposite to the discharge port; a second operation of moving the plunger in a direction toward the discharge port by a distance equal to or equal to the distance S; a third operation of moving the plunger in a direction toward the discharge port by a distance equal to or equal to the distance S; and a fourth operation of moving the plunger in a direction opposite to the discharge port by a distance equal to or equal to the distance S.

In addition, when the liquid material filled in the metering portion is continuously discharged a plurality of times, the preliminary operation may be performed only before the liquid material filled in the metering portion is discharged for the first time.

(Effect of the invention)

According to the present invention, the movement amount or speed of the plunger operation can be kept constant, and the shape of the liquid droplet of the liquid material to be discharged and the discharge state can be stabilized, thereby improving the discharge accuracy.

Drawings

Fig. 1 is a graph showing the time-dependent change of each parameter when the plunger of the discharge device of the present invention performs one discharge operation.

Fig. 2 is a graph showing the time-dependent change of each parameter when the plunger of the conventional discharge device performs one discharge operation.

Fig. 3 is a schematic view of the plunger type discharge device of example 1.

Fig. 4 is a schematic perspective view showing an example of an application device on which the discharge device of embodiment 1 is mounted.

Fig. 5 is an explanatory view for explaining a method of performing the preliminary operation each time in the (1) continuous discharge in example 2.

Fig. 6 is an explanatory diagram for explaining a method of setting the (2) minute reciprocating motion of example 2 as the preliminary motion.

Fig. 7 is an explanatory diagram for explaining a method of setting slow acceleration as the preparatory operation in (3) of embodiment 2.

Fig. 8 is an explanatory diagram for explaining a method of performing only the first preliminary operation in the continuous discharge in (4) of example 2.

Fig. 9 is an explanatory diagram for explaining a method of performing a large preparatory operation in (5) of example 2.

Description of the symbols

1 preparatory action

2 first preparatory actions

3 second preparatory actions

4 discharge device

5 measuring tube (measuring part)

6 plunger

7 discharge port

8 spray nozzle

9 sealing part

10 storage container

11 change valve

12 screw axis

13 driving source (Motor)

14 control device

15 coating device

16 base plate

17 object stage

18XYZ driving mechanism

19 first discharge

20 for the second discharge.

Detailed Description

Hereinafter, an embodiment for carrying out the present invention will be described by taking a discharge device as an example, which is a type including a plunger and a nozzle, and the plunger has a seal portion that slides on an inner wall of a metering portion shown in fig. 3.

The plunger of the discharge device of the present invention shows the time-dependent changes of the respective parameters in the graph shown in fig. 1 when performing one discharge operation. In addition, the plunger of the conventional discharge device shows the change of each parameter with time in the graph shown in fig. 2 when performing one discharge operation. Note that, in fig. 1 and 2, the positive direction of the vertical axis of the graph indicates the discharge port direction, and the negative direction indicates the direction opposite to the discharge port. Further, (a) represents an operation signal of the drive source, (b) represents a change in the moving distance of the plunger, (c) represents a change in the velocity of the plunger with time, and (d) represents a change in the discharge amount at the discharge port.

Hereinafter, the two diagrams of fig. 1 and 2 will be described while comparing them.

In order to improve the discharge accuracy and stabilize the discharge amount, it is necessary to make the deviation of the plunger operation from the operation signal of the drive source infinitely close to zero. In particular, the change in the plunger speed with time has a great influence on the droplet shape or the discharge state. In the conventional operation method shown in fig. 2, as is clear from the graph of the change with time in the plunger speed in (c), the plunger operation is unstable during the period (between 0 and a) from the start of the operation to the time when the plunger speed reaches the highest speed. This is because the frictional resistance acting between the sealing portion of the plunger and the inner wall surface of the metering portion is affected by the change from the static friction at the start of operation to the dynamic friction at the time of operation. Therefore, an unstable portion of the operation signal that does not follow the drive source exists in the plunger, and the discharge amount is unstable.

Therefore, in the present invention, in order to remove the influence of the change from the static friction to the dynamic friction, as shown in fig. 1, the preliminary operation 1 is performed before the discharge operation, and only the dynamic friction acts during the discharge operation.

The preparatory operation 1 is composed of a first preparatory operation 2 and a second preparatory operation 3.

First, the first preparatory movement 2 is to move the plunger only a predetermined distance S (0 to a) in the opposite direction of the discharge port. At this time, some air is sucked into the nozzle from the discharge port. This is to prevent the liquid material from being discharged by the preparatory operation 1. The amount of movement (distance S) of the plunger needs to be set by obtaining a distance necessary for stabilizing the speed of the plunger through a preliminary experiment or the like.

The plunger movement condition in the preliminary operation is preferably in a range where air bubbles are not generated by suction into the nozzle. Here, in order to prevent the generation of bubbles, it is important that the space formed by the air sucked into the nozzle by the preliminary operation is constantly kept in communication with the outside (outside air) through the discharge port. The conditions such as the amount of movement and the moving speed of the plunger are determined and set by experiments in advance, taking into consideration factors such as the shape of the flow path in the nozzle and the properties of the liquid material.

Next, the second preparatory movement 3 is to move the plunger toward the discharge port by the same or equivalent distance (a to B) as the set distance S. This is to fill the space of the air existing in the nozzle by the suction by the above operation with the liquid material again. In this way, a correct amount of discharge can be performed. In addition, the transition to the discharge operation can be smoothly continued.

Then, the plunger is not stopped or decelerated even after the second preparatory operation 3 is finished, and the process proceeds directly to the discharge operation (B to C). In this way, the preliminary operation 1 is performed before the discharge operation, and the frictional resistance does not change from static friction to dynamic friction during the discharge operation, so that the plunger operation is stable and a correct amount of discharge can be performed.

The following examples are provided to illustrate the detailed aspects of the present invention, but the present invention is not limited to any examples.

Example 1

(Structure of discharge device)

The discharge device of the present embodiment will be described below with reference to fig. 3. The liquid material used in this example was liquid crystal (viscosity about 20mPa · s).

The discharge device 4 shown in fig. 3 is configured to include: a tubular metering tube 5; a plunger 6 inscribed in the metering tube 5 by a seal 9; a nozzle 8 having a discharge port 7; a storage container 10 for storing a liquid material; a change-over valve 11 for switching communication between the measuring pipe 5 and the nozzle 8 or between the storage container 10 and the measuring pipe 5; a motor 13 as a driving source for driving the screw shaft 12 to drive the plunger 6; and a control device 14 for controlling the operation of the switching valve 11, the motor 13, and the like. In order to smoothly supply the liquid material, the storage container 10 is connected to a compressed gas source, not shown, via a control device 14, and receives a supply of compressed gas.

(operation of discharge device)

The metering tube 5 is initially filled with liquid material. First, the plunger 6 that is in close contact with and slides in the metering tube 5 is advanced to a position closest to the change valve 11. Then, the change-over valve 11 is switched to a position where the reservoir 10 and the metering tube 5 communicate with each other, and the plunger 6 is moved backward. In this way, the liquid material in the storage container 10 flows into the measuring tube 5 through the change-over valve 11, and when the plunger 6 retreats to the uppermost end of the measuring tube 5, the filling is completed.

Next, the filled liquid material is discharged by switching the change-over valve 11 to a position where the measuring pipe 5 and the nozzle 8 communicate with each other, and moving the plunger 6 in and out in accordance with a desired discharge amount.

The discharge operation of the plunger 6 is to rapidly stop the motor 13 after rapidly accelerating the motor 13 by operating the motor 13, thereby rapidly stopping the plunger 6. In this way, the liquid material in the measuring tube 5 is ejected from the tip of the nozzle 8 by the inertial force caused by the rapid movement and rapid stop of the plunger 6. This discharge operation is repeated to discharge the liquid material in the measuring tube 5 a plurality of times. Here, the discharge operation of the plunger 6 is continuously performed together with the preliminary operation 1 of fig. 1. The preparatory operation 1 and the discharge operation are performed by moving the plunger in the opposite direction of the discharge port by a predetermined distance S calculated in advance as a first preparatory operation 2, and moving the plunger in the direction of the discharge port by the distance S as a second preparatory operation 3, and continuing with the second preparatory operation 3 by a distance corresponding to the discharge amount.

When the plunger 6 reaches a position closest to the change-over valve 11, the change-over valve 11 is switched to a position where the reservoir 10 and the metering tube 5 communicate with each other, and the plunger 6 is moved backward to be filled with the liquid material again.

In this way, the liquid material is filled into the measuring tube 5 from the reservoir 10, the preliminary operation is performed, and the continuous operation of discharging the liquid material in the measuring tube 5 from the nozzle 8 is repeated to perform the discharging operation.

Since the measuring tube 5 of the present embodiment has a capacity capable of being filled with a small amount of liquid material that can be continuously discharged a plurality of times, the liquid material in the measuring tube 5 may be discharged a plurality of times until the liquid material is used up. On the other hand, the filling may be performed at each discharge operation.

Further, when the plunger is stopped at the end of the discharge operation, the force for breaking the liquid material discharged from the nozzle may be controlled by controlling the moving speed of the plunger moving in and out from the start of deceleration to the stop (see japanese patent No. 4183577).

(construction of coating apparatus)

The discharge device 4 may be used alone, but may be mounted on a drive mechanism that moves relative to a substrate to be coated, such as a glass substrate used in a liquid crystal panel manufacturing process or a printed circuit board on which an electronic device is mounted, and may perform operations. Fig. 4 shows an example of an application device on which the discharge device 4 is mounted.

The coating device 15 shown in fig. 4 includes: the above-described discharge device 4; a stage 17 on which a substrate 16 to be coated is placed; an XYZ drive mechanism 18 in which the discharge device 4 is disposed and which relatively moves the discharge device 4 in the XYZ direction above the stage 17; and a control device for controlling the actions of these components. In the coating operation, the discharge device 4 is moved to a desired position on the substrate 16 by the drive mechanism 18 and discharged.

In fig. 4, a plurality of discharge devices 4 are mounted in order to operate the discharge devices 4 simultaneously and shorten the operation time for the large substrate 16. The number of the mounted ejection devices 4 is not limited to 3 shown in fig. 4, and may be 2 or less, or 4 or more. That is, it is determined appropriately according to the size of the substrate 16, the limitation of the working time that can be spent, and the like.

(effects of the embodiment)

In the discharge device performing the preliminary operation according to the present embodiment, it was confirmed that the accuracy can be improved by about 80% (variation is reduced) compared to the conventional discharge device not performing the preliminary operation (the same mechanical structure).

Example 2

In example 2, a method of performing discharge by combining different types of preliminary operations in the same discharge apparatus as in example 1 will be described. Fig. 5 to 9 show the change in plunger speed with time.

(1) Method of performing preparatory operation every time in continuous discharge [ FIG. 5]

When the liquid material in the measuring portion is continuously discharged a plurality of times after the measuring portion is filled once, if importance is attached to the discharge interval being long or the discharge accuracy, as shown in fig. 5, the preliminary operation 1 is performed at the start of each discharge operation. In this way, the accuracy of discharge at each time can be improved, and variations between discharges can be reduced.

(2) Method for setting minute reciprocating motion as preparatory motion [ FIG. 6]

The plunger 6 is normally stopped when the discharge operation is not performed. Therefore, as shown in fig. 6, the minute reciprocating motion 23 is repeated in a portion corresponding to the stop time, and the state of losing the standstill is obtained. That is, since the state is always in a dynamic state, the number of portions where the frictional resistance changes is reduced, and stable and accurate discharge is possible. This is advantageous in the case where the number of times of discharge is reduced or the discharge interval is lengthened.

(3) Method for setting slow acceleration as preparatory operation [ FIG. 7]

When the plunger 6 is moved in the direction opposite to the discharge port 7, some air is sucked from the discharge port 7. In the next operation, the movement is performed by the same distance in the direction toward the discharge port 7, but the influence may be considered. Therefore, as shown in fig. 7, the plunger is not moved in the direction opposite to the discharge port 7, but is gradually accelerated in the direction of the discharge port 7 at the portion where the discharge operation is started (reference numeral 24), and the influence of the portion where the frictional resistance is changed on the discharge is reduced. In this way, air is not sucked from the discharge port 7, and an effect of reducing the influence of the change in the frictional resistance can be obtained.

(4) Method for performing only primary preparatory operation during continuous discharge [ FIG. 8]

As shown in the embodiment, the preliminary operation 1 of the present invention is basically performed once every time one discharge operation is performed. However, it has been found through experiments that, when a plurality of times of ejection are continuously performed, if the ejection interval is shortened, a portion where the static friction is changed to the dynamic friction becomes smaller or substantially disappears during a period from the stop of one ejection operation to the next ejection operation. As shown in fig. 8, the preliminary operation 1 may be performed only at the start of the first discharge 19 in the continuous multi-discharge, and the preliminary operation 1 may not be performed after the second discharge 20. In this way, the time required for the preliminary operation 1 after the second discharge 20 can be shortened, and the work can be performed more efficiently. This method is effective when speed is regarded as important. Whether or not the operation of the present embodiment is performed must be determined in accordance with the state of the inner surface of the measuring tube 5 or the surface of the sealing portion 9, the force with which the sealing portion 9 presses the inner surface of the measuring tube 5, and the like. Therefore, the determination can be made by obtaining the target of the discharge interval through a preliminary experiment or the like.

(5) Method for performing a large preparatory movement [ FIG. 9]

In some cases, the large preparatory operation 1 must be performed depending on the state of the seal 9 of the plunger 6 or the measuring tube 5. In this case, the influence on the subsequent discharge operation is considered. Therefore, as shown in fig. 9, after the large preparatory operation 21, the same magnitude of operation 22 is performed in the opposite direction, and the influence on the subsequent discharge operation can be reduced. In this way, the preparatory operation can be performed without being limited by the size. This configuration is also effective when the small preparatory operation of (1) or (4) is performed. Further, if the discharge interval is shortened, only the first preliminary operation may be performed as in the above-described method (4).

Industrial applicability

The present invention is suitable for a device that moves a plunger while sliding the plunger in close contact with the inside of a metering section to discharge a droplet of liquid material. The present invention is effective for all liquid materials which can be ejected by a plunger, and is applicable to the ejection of highly viscous fluids from low-viscosity substances such as water and ethanol to adhesives, liquid crystal materials, and industrial materials (such as flux and lubricating oil) in the form of paste or cheese.

Claims (7)

1. A method for discharging a liquid material, the method comprising a metering section for metering the liquid material, a discharge port communicating with one end of the metering section, and a plunger slidably moving on an inner wall of the metering section, the method comprising the steps of: a filling step of moving the plunger in a direction opposite to the discharge port to fill the liquid material into the metering section; and a discharging step of moving the plunger in the direction of the discharge port and then stopping the movement of the plunger, thereby causing the liquid material to fly and discharge from the discharge port; the method of discharging a liquid material is characterized in that,

a preliminary operation step of moving the plunger without discharging the liquid material is provided for controlling the speed of the plunger in the discharging step to be constant,

the preparatory actions include: a first operation of moving the plunger by a predetermined distance S in a direction opposite to the discharge port; and a second operation of moving the plunger in a direction toward the discharge port by a distance equal to or equal to the distance S.

2. The method of discharging a liquid material according to claim 1, wherein the predetermined distance S is set to a distance that accelerates the plunger to a certain speed.

3. The method of discharging a liquid material according to claim 1 or 2, wherein the first operation and the second operation are repeated after the filling operation until the discharging operation is started.

4. The method for discharging a liquid material according to claim 1 or 2, wherein the first action is to move the plunger under a condition that bubbles are not generated in the external gas sucked from the discharge port.

5. The method according to claim 1 or 2, wherein the preparatory operation and the discharge step are performed continuously.

6. A discharge device for liquid material, characterized in that,

the method comprises the following steps: a metering section for metering a liquid material; a discharge port communicated to one end of the metering portion; a plunger that slidably moves against an inner wall of the metering section; a drive source for driving the plunger; and a control device;

the control device is capable of implementing the discharge method of claim 1 or 2.

7. A device for applying a liquid material, characterized in that,

the disclosed device is provided with: a stage on which an object to be coated is placed; the discharge device of claim 6; and a relative movement mechanism for moving the discharge device and the stage relative to each other.