KR102511749B1 - Device for discharging liquid material and method for discharging liquid material - Google Patents

Abstract

A liquid dispensing device capable of suppressing an increase in startup time of the device is provided.
The discharge portion includes a supply port through which the liquid material is supplied, a discharge port through which the liquid material supplied from the supply port is discharged, and a discharge port through which liquid material that has not been discharged is discharged. The control device has a first control amount dependent on the meniscus pressure of the liquid material in the discharge port and a second control amount dependent on the differential pressure between the pressure at the discharge port and the pressure at the discharge port, respectively, a first target value that is a target value of the first control amount. , and control to be maintained at the second target value, which is the target value of the second control variable. The control device performs control for bringing the first control amount closer to the first target value in the period until the first control amount and the second control amount approach the first target value and the second target value, respectively, the second control amount It has a function of prioritizing and executing the control for approaching the second target value.

Description

Liquid material discharging device and liquid material discharging method {Device for discharging liquid material and method for discharging liquid material}

This application claims priority based on Japanese Patent Application No. 2017-170503 filed on September 5, 2017. The entire content of that application is incorporated herein by reference.

The present invention relates to a liquid material discharging device and a liquid material discharging method for discharging liquid from a discharge port.

Patent Document 1 below discloses an ink supply system for circulating and supplying ink from a subtank to an ink jet head through an ink circulation path. In this ink supply system, pressure sensors are disposed on the upstream and downstream sides of the inkjet head, respectively. The controller calculates the ink pressure at the position of the nozzle of the inkjet head based on the detection value of the pressure sensor, and controls the pressure in the sub-tank so that the pressure becomes a predetermined value.

Patent Document 1: Japanese Unexamined Patent Publication No. 2015-157362

There are cases in which it is desired to control not only the ink pressure at the position of the nozzle (ink pressure in the nozzle) but also the flow rate of ink flowing through the inkjet head. For example, when adopting a configuration in which ink is heated and circulated, it is preferable to keep the flow rate of ink constant in order to keep the temperature of ink constant. In this way, it has been found that when a control system having two physical quantities to be controlled and two degrees of freedom is constituted, a new problem arises in that the start-up time of the device becomes long.

An object of the present invention is to provide a liquid material ejecting device and a liquid material ejecting method capable of suppressing the lengthening of the startup time of the device.

According to one aspect of the present invention,

A discharge portion including a supply port through which liquid material is supplied, a discharge port through which the liquid material supplied from the supply port is discharged, and a discharge port through which the liquid material that has not been discharged is discharged;

A first control amount dependent on the meniscus pressure of the liquid material in the discharge port, and a second control amount dependent on the differential pressure between the pressure at the discharge port and the pressure at the discharge port, each of which is a target value of the first control amount. A control device for controlling to be maintained at a target value and a second target value that is a target value of the second control amount,

In a period until the first control amount and the second control amount approach the first target value and the second target value, respectively, the control device controls the first control amount to approach the first target value. There is provided a liquid material dispensing device having a function of executing the control of making the second control amount prior to the control of bringing the second control amount closer to the second target value.

According to another aspect of the present invention,

Supplying and discharging the liquid material to a discharge unit including a supply port through which the liquid material is supplied, a discharge port through which the liquid material supplied from the supply port is discharged, and a discharge port through which the liquid material that has not been discharged is discharged. As a method,

A first control amount, which is the meniscus pressure of the liquid material in the discharge port, and a second control amount, which is a differential pressure between the pressure of the discharge port and the pressure of the discharge port, are respectively a first target value that is a target value of the first control amount, and the first control amount. Control by a first control mode for supplying and discharging the liquid material so as to be maintained at a second target value, which is a target value of 2 control amounts;

In a second control mode in which, prior to control by the first control mode, control for bringing the first control amount closer to the first target value is executed prior to control for bringing the second control amount closer to the second target value. A liquid material dispensing method that is controlled by

The time for bringing the first control amount and the second control amount closer to the first target value and the second target value, respectively, becomes shorter. In this way, it is possible to suppress the lengthening of the start-up time of the device.

1 is a schematic diagram of a liquid material dispensing device according to an embodiment.
Fig. 2 is a schematic control block diagram of a control system for controlling the meniscus pressure Pma and differential pressure Pda.
FIG. 3 is a graph showing an example of changes over time in meniscus pressure Pma and differential pressure Pda when control is performed by the control method shown in FIG. 2 .
4 is a flow chart of a liquid material discharging method according to an embodiment.
5 is a control block diagram showing an example of the control executed in step S1.
6 is a control block diagram showing an example of the control executed in step S3.
Fig. 7 shows an example of the temporal change of the meniscus pressure Pma and the differential pressure Pda when the meniscus pressure Pma and the differential pressure Pda are set using the liquid material discharging method according to the embodiment. It is a graph that represents

Referring to Figs. 1 to 7, a liquid material ejection device according to an embodiment of the present invention will be described.

1 is a schematic diagram of a liquid material dispensing device according to an embodiment. Ink, which is a liquid material, is accommodated in the sub tank 20 . A heater 35 is disposed in the sub tank 20 and the heater 35 heats the ink in the sub tank 20 .

Ink in the sub tank 20 passes through the supply path 51 and is supplied to the supply port 11 of the inkjet head (discharge unit) 10 . In the inkjet head 10, an ink chamber extending from the supply port 11 to the discharge port 12 is provided. The inkjet head 10 ejects the ink in the ink chamber from a plurality of ejection ports (nozzles) 13 as droplets. An ejection control device (31) controls ejection of ink from the inkjet head (10).

The ink supplied to the inkjet head 10 and not ejected from the discharge port 13 is discharged from the discharge port 12 . The ink discharged from the outlet 12 is collected in the sub tank 20 through the recovery path 52 .

A first pump 21 is inserted into the supply path 51 . The first pump 21 supplies the ink in the sub tank 20 toward the supply port 11 of the inkjet head 10 . A first buffer tank 22 is inserted into the supply path 51 between the first pump 21 and the inkjet head 10 . The first buffer tank 22 suppresses the pulsation of the ink delivered from the first pump 21 .

A first pressure sensor 23 is mounted in the supply path 51 between the first buffer tank 22 and the supply port 11. The first pressure sensor 23 measures the pressure of the ink flowing into the supply port 11 and obtains a measured value Psa.

A second pump 24 is inserted into the recovery path 52 . The second pump 24 discharges ink from the inkjet head 10 through the discharge port 12 and supplies it toward the sub tank 20 . A second buffer tank 25 is inserted into the recovery path 52 between the second pump 24 and the inkjet head 10 . The second buffer tank 25 suppresses pulsation of the ink sucked by the second pump 24 .

A second pressure sensor 26 is mounted in the return path 52 between the second buffer tank 25 and the outlet 12. The second pressure sensor 26 measures the pressure of the ink discharged from the outlet 12 to obtain a measured value Pra.

When the ink in the sub tank 20 decreases, the sub tank 20 is replenished with ink from the main tank 40 . A drain pipe 55 is provided in the sub tank 20 . When cleaning the path of ink in the liquid material ejection device, ink is discharged from the sub tank 20 through the drain pipe 55.

The controller (control device) 30, based on the measured values (Psa, Pra) of the first pressure sensor 23 and the second pressure sensor 26, the first pump 21 and the second pump 24 control the output of The controller 30 can be realized with, for example, a programmable logic controller (PLC). In order to stably discharge ink from the discharge port 13, the meniscus pressure of the ink at the position of the discharge port 13 (at the discharge port 13 when the ink meniscus is formed in the discharge port 13) It is preferable to control the pressure of the ink) to an appropriate negative pressure (pressure below atmospheric pressure). Further, in order to keep the temperature of the circulating ink constant, it is preferable to control the flow rate of the ink within an appropriate range.

The meniscus pressure is measured from the measured value Psa of the first pressure sensor 23, the measured value Pra of the second pressure sensor 26, and the mounting position of the first pressure sensor 23 through the supply port 11. flow resistance Rs from the discharge port 12 to the mounting position of the second pressure sensor 26, and the height from the discharge port 13 to the liquid level of the ink in the sub tank 20 ( H) depends on the hydrostatic pressure (Ph). For example, the meniscus pressure (Pma) can be represented by the following formula.

Pma=(Rr/(Rs+Rr))Psa+(Rs/(Rs+Rr))Pra+Ph... (One)

The flow rate of ink circulating through the sub tank 20, the supply path 51, the inkjet head 10, and the recovery path 52 is determined by the measured value Psa of the first pressure sensor 23 and the second pressure sensor (26) depends on the difference between the measured values Pra. Hereinafter, Psa-Pra is simply referred to as differential pressure (Pda).

In order to maintain the temperature of the circulating ink at the target value and stably discharge the ink, the meniscus pressure (Pma) and the flow rate of the ink may be maintained at the target value, respectively. In this embodiment, the meniscus pressure Pma (first control amount) and the differential pressure Pda (second control amount) are taken as the first control amount and the differential pressure Pda is the second control amount. control amount) is maintained at the meniscus pressure target value Pmc (first target value) and differential pressure target value Pdc (second target value), respectively. This control can be performed by controlling the output of the 1st pump 21 and the 2nd pump 24, for example.

Fig. 2 is a schematic control block diagram of a control system for controlling the meniscus pressure Pma and differential pressure Pda. In Fig. 2, display of functions such as gain, time delay, low-pass filter, and averaging filter is omitted. The deviation Pme between the meniscus pressure target value Pmc and the meniscus pressure Pma is input to the PID control block, and the meniscus pressure manipulation amount Pmo is output. The difference Pde between the pressure difference target value Pdc and the pressure difference Pda is input to another PID control block, and the pressure difference manipulation amount Pdo is output.

Based on the non-inverted value of the meniscus pressure manipulated variable Pmo and the non-inverted value of the differential pressure manipulated variable Pdo, the first pump command value Psc is determined. The output of the 1st pump 21 is controlled by the 1st pump command value Psc. The second pump command value Prc is determined based on the inverted value of the meniscus pressure manipulated variable Pmo and the non-inverted value of the differential pressure manipulated variable Pdo. The output of the second pump 24 is controlled by the second pump command value Prc.

The meniscus pressure calculation block 61 calculates the meniscus based on the measured value Psa of the first pressure sensor 23, the measured value Pra of the second pressure sensor 26, and the head pressure Ph. Curse pressure (Pma) is output. For derivation of the meniscus pressure Pma, for example, the expression (1) described above may be used. The differential pressure calculation block 62 outputs the differential pressure Pda based on the measured value Psa of the first pressure sensor 23 and the measured value Pra of the second pressure sensor 26 . For example, the differential pressure Pda may be calculated by the following formula.

Pda = Psa-Pra... (2)

When the meniscus pressure Pma becomes smaller than the meniscus pressure target value Pmc, control is performed in the direction of increasing the output of the first pump 21 and lowering the output of the second pump 24 . As a result, the meniscus pressure Pma rises. When the meniscus pressure Pma becomes larger than the meniscus pressure target value Pmc, the opposite control is performed, and as a result, the meniscus pressure Pma decreases.

When differential pressure Pda becomes smaller than differential pressure target value Pdc, control to raise the output of both the 1st pump 21 and the 2nd pump 24 is performed. As a result, the differential pressure Pda increases. When the differential pressure Pda becomes larger than the differential pressure target value Pdc, the opposite control is performed, and as a result, the differential pressure Pda decreases.

Next, before explaining the liquid material discharge method according to the embodiment, when the meniscus pressure Pma and the differential pressure Pda are set to the meniscus pressure target value Pmc and the differential pressure target value Pdc, respectively. The problems in the period up to will be described. This problem was newly discovered by the inventors of the present application by actually operating the liquid material dispensing device. Here, “setting” means that control amounts such as the meniscus pressure Pma and differential pressure Pda fall within a target range including the target values.

In the control block diagram shown in Fig. 2, the second pump command value Prc is set based on the difference between the differential pressure operation amount Pdo and the meniscus pressure operation amount Pmo. For this reason, depending on the initial state immediately after the start of control or the state in the middle of setting, the differential pressure manipulated amount Pdo and the meniscus pressure manipulated amount Pmo cancel each other, so that the second pump command value Prc is small. There are times when it is canceled. Due to this, the time required until the meniscus pressure Pma and the differential pressure Pda are set may increase.

Fig. 3 is a graph showing an example of changes over time in meniscus pressure Pma and differential pressure Pda when control is performed by the control method shown in Fig. 2; The horizontal axis represents elapsed time, and the vertical axis represents pressure in arbitrary units. The thick solid line and the thin solid line in FIG. 3 represent the temporal changes of the meniscus pressure (Pma) and differential pressure (Pda), respectively.

When the control is started at time 0, the meniscus pressure Pma and the differential pressure Pda gradually approach the meniscus pressure target value Pmc and the differential pressure target value Pdc, respectively. Here, the meniscus pressure target value Pmc becomes negative in gauge pressure. In this method, about 1500 seconds were required from control start to setting completion. Because of this, it is necessary to wait at least 1500 seconds from starting the device to the ejection operation of the ink. In the embodiment described below, the setting time can be shortened.

4 is a flow chart of a liquid material discharging method according to an embodiment. Each process in this flowchart is executed by the controller 30 (FIG. 1). When control is started, first, control to bring the differential pressure Pda closer to the differential pressure target value Pdc is not performed, but control to bring the meniscus pressure Pma closer to the meniscus pressure target value Pmc is performed (step S1 ). For example, control is performed to set the meniscus pressure Pma within a target range including the meniscus pressure target value Pmc. The control mode of step S1 is referred to as "meniscus pressure setting mode". That is, the control to bring the meniscus pressure Pma closer to the meniscus pressure target value Pmc is performed prior to the control of the differential pressure Pda.

Fig. 5 is a control block diagram showing an example of meniscus setting mode control. The differential pressure operation amount Pdo is not used for control of either the first pump 21 or the second pump 24 . For this reason, control to bring the differential pressure Pda closer to the differential pressure target value Pdc is not performed. Based on the inverted value of the meniscus pressure operation amount Pmo, the second pump command value Prc for the second pump 24 is determined.

The 1st pump command value Psc is fixed to the command value PscL which operates the 1st pump 21 at an output lower limit value. As a result, the first pump 21 is driven at the lower output limit. Since the meniscus pressure operation amount Pmo is fed back to the output control of the second pump 24, the meniscus pressure Pma approaches the meniscus pressure target value Pmc by this control.

The controller 30 determines whether the meniscus pressure Pma has approached the meniscus pressure target value Pmc (step S2). If the meniscus pressure Pma is set within the target range including the meniscus pressure target value Pmc, step S3 is executed. This target range may be wider than the target range for setting the meniscus pressure Pma when discharging the liquid material. In step S3, control is performed to bring the differential pressure Pda closer to the differential pressure target value Pdc while preventing divergence of the meniscus pressure Pma. For example, control is performed to set differential pressure Pda within a target range including differential pressure target value Pdc. The control mode of step S3 is called "differential pressure setting mode".

6 is a control block diagram showing an example of control in the differential pressure setting mode. The first pump command value Psc is determined based on the non-inverted value of the differential pressure operation amount Pdo. This control acts in the direction of increasing the output of the first pump 21 when the differential pressure Pda becomes smaller than the differential pressure target value Pdc, and when the differential pressure Pda becomes larger than the differential pressure target value Pdc, the first pump It acts in the direction of lowering the output of (21).

The second pump command value Prc is determined based on the value obtained by inverting the meniscus pressure manipulation amount Pmo and the inverted value of the differential pressure manipulation amount Pdo. The reason why the value obtained by inverting the meniscus pressure manipulation amount Pmo is used for feedback control is to prevent divergence of the meniscus pressure Pma close to the meniscus pressure target value Pmc in step S1 (FIG. 4). Further, in the control in the steady state shown in Fig. 2, the second pump command value Prc was determined based on the non-inverted value of the differential pressure operation amount Pdo. The reason why the differential pressure manipulated amount Pdo is reversed in step S3 is to avoid that the meniscus pressure manipulated amount Pmo and the differential pressure manipulated amount Pdo cancel each other.

This control acts in the direction of increasing the output of the first pump 21 and lowering the output of the second pump 24 when the differential pressure Pda becomes smaller than the differential pressure target value Pdc. When the differential pressure Pda is greater than the differential pressure target value Pdc, the output of the first pump 21 is reduced and the output of the second pump 24 is increased.

When the differential pressure Pda is smaller than the differential pressure target value Pdc, the control for increasing the output of the first pump 21 acts in the direction of increasing the differential pressure Pda, but increases the output of the second pump 24. The lowering control works in the direction of reducing the differential pressure Pda conversely. For this reason, if the magnitude acting in the direction of increasing the differential pressure Pda and the magnitude acting in the direction of decreasing the differential pressure Pda are balanced, it is also possible that the differential pressure Pda does not approach the differential pressure target value Pdc. can think

Next, the reason why the differential pressure Pda approaches the differential pressure target value Pdc by the above control will be described. When the control mode is the differential pressure setting mode, as shown in FIG. 6 , the meniscus pressure manipulated amount Pmo is connected only to the second pump 24 . Under the influence of the increase in the output of the first pump 21 by the differential pressure operation amount Pdo, the output of the second pump 24 is increased by the meniscus pressure operation amount Pmo, and the ink discharged from the discharge port 12 pressure is reduced. As a result, the balance for the differential pressure Pda is broken, and the differential pressure Pda approaches the differential pressure target value Pdc.

The controller 30 determines whether the differential pressure Pda has approached the differential pressure target value Pdc (step S4). If the differential pressure Pda is set within the target range including the differential pressure target value Pdc, step S5 is executed. This target range may be wider than the target range in which the differential pressure Pda is set when discharging the liquid material. In step S5, control is performed to maintain both the meniscus pressure Pma and the differential pressure Pda at the meniscus pressure target value Pmc and the differential pressure target value Pdc, respectively. In step S5, control by the control block diagram shown in FIG. 2 is performed. The control mode of step S5 is referred to as "precise setting mode".

The liquid material is discharged in a state where the meniscus pressure Pma and differential pressure Pda are within the set target width. During dispensing of the liquid material, control in the precise setting mode is continuously executed. When the ejection processing is ended, this control is ended (step S6).

Next, with reference to FIG. 7, excellent effects of the liquid material discharging method according to the above embodiment will be described.

Fig. 7 shows an example of the time change of the meniscus pressure Pma and the differential pressure Pda when the meniscus pressure Pma and the differential pressure Pda are set using the liquid material discharging method according to the embodiment. It is a graph that represents The horizontal axis represents elapsed time, and the vertical axis represents pressure in arbitrary units. The thick solid line and the thin solid line in FIG. 3 represent the temporal changes of the meniscus pressure (Pma) and differential pressure (Pda), respectively.

Periods T1, T2, and T3 in Fig. 7 correspond to the controllers in the meniscus pressure setting mode (step S1), differential pressure setting mode (step S3), and precision setting mode (step S5) in Fig. 4, respectively. During the period T1, since the meniscus pressure Pma is controlled, the meniscus pressure Pma approaches the meniscus pressure target value Pmc. However, since the differential pressure Pda is not controlled, the differential pressure Pda hardly approaches the differential pressure target value Pdc. In the period T2, since the control of the differential pressure Pda is performed, the differential pressure Pda approaches the differential pressure target value Pdc more rapidly than in the period T1. The meniscus pressure Pma temporarily changes in a direction away from the meniscus pressure target value Pmc, but does not diverge and gradually approaches the meniscus pressure target value Pmc.

In the period T3, there occurs a period in which the meniscus pressure Pma and the differential pressure Pda temporarily move away from the meniscus pressure target value Pmc and the differential pressure target value Pdc, but after that, the meniscus pressure Curse pressure target value Pmc and differential pressure target value Pdc are rapidly approaching. Both the meniscus pressure (Pma) and differential pressure (Pda) were set after about 90 seconds from the start of control.

When control of steps S2 and S4 (FIG. 4) was not performed, as shown in FIG. 3, for example, about 1500 seconds were required until setting. In contrast to this, in the method according to the embodiment, the time required until setting could be shortened to, for example, 90 seconds. In this way, it is possible to improve the operation rate of the liquid material discharging device. In addition, since the warming time of the ink is shortened, an energy saving effect is also obtained.

In the above embodiment, in step S1 (FIG. 4), the meniscus pressure Pma is controlled by operating the first pump 21 at the output lower limit value and changing the output of the second pump 24. . Since the first pump 21 operates at the lower output limit value, the meniscus pressure Pma can be quickly reduced to negative pressure by increasing the output of the second pump 24 slightly higher than the lower output limit value.

In contrast, in the example shown in Fig. 3, the time from the start of control until the meniscus pressure Pma becomes negative is about 750 seconds. Until the meniscus pressure (Pma) becomes a negative pressure, ink spillage from the discharge port 13 of the inkjet head 10 tends to occur. In the method according to the above embodiment, since the meniscus pressure (Pma) can be set to negative pressure in a short time, ink spillage from the ejection port 13 of the inkjet head 10 is unlikely to occur.

In the above embodiment, the feedback control was performed with the meniscus pressure Pma defined in equation (1) as the first control amount and the differential pressure Pda defined in equation (2) as the second control amount. As another configuration, a physical quantity dependent on the meniscus pressure Pma rather than the meniscus pressure Pma itself may be the first control quantity, and a physical quantity dependent on the differential pressure Pda may be the second control quantity. For example, when the head pressure Ph shown in Formula (1) is constant, it is good also considering the sum of the 1st term and the 2nd term of the right side of Formula (1) as a 1st control amount. In the case where the flow resistance Rs and the flow resistance Rr are the same, the meniscus pressure Pma is expressed by the following equation.

Pma=(Psa+Pra)/2+Ph... (3)

Therefore, when the head pressure Ph is constant, it is good also considering Psa+Pra as a 1st control amount. In particular, a physical quantity having a one-to-one correspondence relationship with the meniscus pressure depending on the meniscus pressure Pma may be used as the first control variable. Similarly, depending on the differential pressure Pda, a physical quantity having a one-to-one correspondence with the differential pressure Pda may be used as the second control variable.

Next, a modified example of the above embodiment will be described.

In the above embodiment, in the meniscus setting mode (step S1), the first pump 21 is operated at the output lower limit value, and the output of the second pump 24 is changed. As another method, the output of the 1st pump 21 may be changed by operating the 2nd pump 24 at the output upper limit value, for example.

In the above embodiment, the control of the meniscus pressure Pma is temporally prioritized over the control of the differential pressure Pda, and the control of the meniscus pressure Pma is performed before the control of the differential pressure Pda. Instead of giving priority to time, control of the meniscus pressure Pma may be prioritized by making the feedback amount of the meniscus pressure Pma larger than the feedback amount of the differential pressure Pda. Also in this case, in the initial stage from the start of control, the speed at which the meniscus pressure Pma approaches the meniscus pressure target value Pmc is the speed at which the differential pressure Pda approaches the differential pressure target value Pdc. A faster period appears.

In the above embodiment, the meniscus pressure Pma and differential pressure Pda were controlled by changing the outputs of the two pumps. Instead of changing the outputs of the two pumps, at least two operating variables affecting the meniscus pressure Pma and the differential pressure Pda may be changed. As the manipulated variable to be changed, any two of the output of the pump, the flow resistance, and the pressure in the sub tank 20 can be selected.

The above embodiments are examples, and the present invention is not limited to the above embodiments. For example, it will be apparent to those skilled in the art that various changes, improvements, combinations, and the like are possible.

10 Inkjet head (discharge part)
11 supply port
12 outlet
13 outlet
20 subtank
21 first pump
22 1st buffer tank
23 first pressure sensor
24 second pump
25 Second buffer tank
26 second pressure sensor
30 controller (control device)
31 Discharge control device
35 heater
40 main tank
51 supply channels
52 recovery route
55 drain pipe
61 Meniscus Rolling Block
62 differential operation block

Claims (8)

A discharge portion including a supply port through which liquid material is supplied, a discharge port through which the liquid material supplied from the supply port is discharged, and a discharge port through which the liquid material that has not been discharged is discharged;
A first control amount, which is the meniscus pressure of the liquid material in the discharge port, and a second control amount, which is the differential pressure between the pressure at the discharge port and the pressure at the outlet, are constant first target values that are target values of the first control amount, and the A control device for controlling the second control amount to be maintained at a constant second target value, which is a target value of the second control amount;
The control device supplies the liquid material from the supply port to the discharge unit in a period until the first control amount and the second control amount approach the first target value and the second target value, respectively. And while discharging the liquid material from the discharge port, having a function of executing control for bringing the first control amount closer to the first target value in preference to control for bringing the second control amount closer to the second target value Liquid material dispensing device. According to claim 1,
The control device,
Performing control to set the first control amount within a first target range including the first target value;
Then, control is performed to set the second control amount within a second target range including the second target value,
Then, the liquid material dispensing device performs control to maintain the first control amount and the second control amount at the first target value and the second target value. According to claim 1 or 2,
A first pressure sensor for measuring the pressure of the liquid material flowing into the supply port;
Further having a second pressure sensor for measuring the pressure of the liquid material discharged from the outlet,
wherein the control device obtains the second control amount based on a difference between a measured value of the first pressure sensor and a measured value of the second pressure sensor. According to claim 3,
The control device obtains the first control amount based on the sum of the measured values of the first pressure sensor and the measured values of the second pressure sensor and the head pressure applied to the liquid material at the location of the discharge port. material dispensing device. According to claim 1 or 2,
A first pump for sending the liquid material toward the supply port;
Further having a second pump for discharging the liquid material from the outlet,
The control device controls the outputs of the first pump and the second pump, thereby bringing the first control amount and the second control amount closer to the first target value and the second target value, respectively. . According to claim 5,
During a period in which the control device performs control for bringing the first control amount closer to the first target value in priority over control for bringing the second control amount closer to the second target value, the first pump and the second target value are executed. A liquid material dispensing device that operates one of the pumps at a constant output and changes the output of the other pump. Supplying and discharging the liquid material to a discharge unit including a supply port through which the liquid material is supplied, a discharge port through which the liquid material supplied from the supply port is discharged, and a discharge port through which the liquid material that has not been discharged is discharged. As a method,
A first control amount, which is the meniscus pressure of the liquid material in the discharge port, and a second control amount, which is the differential pressure between the pressure at the discharge port and the pressure at the outlet, are constant first target values that are target values of the first control amount, and the Control by a first control mode for supplying and discharging the liquid material so as to be maintained at a constant second target value, which is the target value of the second control amount;
Prior to control by the first control mode, supplying the liquid material from the supply port to the discharge unit and discharging the liquid material from the discharge port, while controlling the first control amount to approach the first target value, A liquid material discharging method for performing control by a second control mode in which priority is given to control for bringing the second control amount close to the second target value. According to claim 7,
In the first control mode, the first control amount is set within a first target range including the first target value, and thereafter, the second control amount is set to a second target value including the second target value. Liquid material dispensing method set within the range.

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