JP7582666B2 - Liquid Supply Unit - Google Patents

Description

The present invention relates to a liquid supply device capable of repeatedly supplying liquid.

The following Patent Document 1 discloses a sheet-fed coating device that applies paint to the top surface of a workpiece. This sheet-fed coating device employs a liquid supply device that includes a tank that contains a liquid such as paint, and a pump that draws in liquid from the tank and supplies the drawn-in liquid. This liquid supply device is capable of repeatedly supplying a fixed amount of liquid, and can be used in a variety of cases, such as when applying a coating liquid to multiple parts, or when supplying or spraying a chemical to multiple test specimens in the same way. A liquid supply device configured in this way is configured so that a piston performs a repetitive motion to repeatedly perform a suction action that draws in liquid from the tank and a delivery action that delivers the drawn-in liquid.

Japanese Patent Application Publication No. 8-182951

In the liquid supply device configured as above, the pressure inside the pump is reduced by the suction action of the piston. For example, conventional liquid supply devices are configured with mechanical check valves on both the suction side and the delivery side of the pump, and there is a problem that liquid is not supplied until the pressure inside the pump reaches the cracking pressure of the delivery side check valve, and the supply of liquid is delayed. Even if a control valve is used instead of a mechanical check valve as in the device of Patent Document 1 above, if the suction side is blocked when the suction action is completed, the pressure inside the pump is in a reduced state, so the pressure difference until liquid can be supplied, and further the pressure difference until the pressure required to discharge liquid in the device receiving the liquid supply from the liquid supply device, becomes large, and there is a problem that switching from the suction action to the delivery action cannot be performed smoothly.

The present invention was made in consideration of such circumstances, and aims to provide a liquid supply device that can smoothly switch from the suction operation to the delivery operation, thereby avoiding delays in the supply of liquid.

In order to solve the above problems, the liquid supply device of the present invention comprises:
A liquid supplying device capable of repeatedly supplying liquid,
A tank for containing a liquid;
a pump having a piston and a drive source for driving the piston, the pump sucking liquid from the tank through a suction passage and delivering the sucked liquid through a delivery passage;
a control valve connected to the suction passage, the discharge passage, and the pump, and capable of switching a communication state between the suction passage and the pump and a communication state between the pump and the discharge passage;
a control device for controlling the pump and the control valve;
The control device is characterized in that after the pump has completed suction of liquid from the tank, it executes suction side connection state maintenance control in the control valve to maintain a state in which the pump and the suction path are connected until a condition is reached in which the pressure in the pump has risen to the pressure of the tank.

When the pump has finished drawing liquid from the tank, the suction by the piston has caused the pressure inside the pump to be lower than the liquid pressure of the liquid contained in the tank. If communication between the pump and the suction path is blocked in this state, the pressure difference until the pressure at which liquid can be discharged in the device receiving the liquid from the liquid supply device (hereinafter sometimes referred to as the "discharge device") will become large, and there will be a delay in the time until the liquid can be supplied. In addition, there is also a problem with the time delay from the command to discharge liquid to the actual discharge of liquid in the discharge device.

In contrast, in a liquid supply device with this configuration, the pressure inside the pump before the discharge operation is increased to the tank pressure by the suction side communication state maintenance control, so the liquid pressure during discharge in the liquid supply device and the pressure difference to the liquid pressure required for the discharge side device are smaller than when the communication between the pump and the suction path is cut off immediately after the suction operation. In other words, with a liquid supply device with this configuration, it is possible to smoothly switch from the suction operation to the discharge operation, avoiding delays in the supply of liquid and delays in the discharge of liquid from the discharge device.

For example, if the discharge device is one that applies or sprays liquid from a nozzle onto an object, and the liquid is applied or sprayed while the nozzle or object is moving, if the liquid pressure in the pump is not stable, the timing at which the nozzle starts to discharge will be unstable, and there is a risk that the liquid cannot be applied or sprayed stably. By adopting a liquid pressure supply device with this configuration, the liquid pressure in the pump before discharge is set to the liquid pressure in the tank, so the timing at which the discharge device starts to discharge can be stabilized.

In this configuration, "the condition that the pressure inside the pump is deemed to have risen to the tank pressure" does not only mean the case where a sensor or the like can actually detect that the pressure inside the pump has reached the tank pressure, but also includes the case where it can be estimated that the pressure inside the pump has reached the tank pressure based on other indicators.

The "pump" in this liquid supply device is one that includes a cylinder and a piston slidably disposed inside it, such as a syringe pump or one that has a diaphragm-type piston, and the intake and delivery operations are performed by the repeated movement of the piston. The "control valve" in this liquid supply device may be one that switches communication with the pump between the intake path and the delivery path, or may be one that is composed of two valves provided in each of the intake path and the delivery path. There are no particular limitations on the drive method of the control valve.

In the above configuration, the liquid supply device is equipped with a pressure sensor that detects the pressure inside the pump, and the control device can be configured to block the pump and the suction path when the pressure detected by the pressure sensor becomes equal to or greater than the pressure of the tank during the suction side communication state maintenance control.

A liquid supply device with this configuration can use a pressure sensor to detect when the pressure inside the pump has risen to the tank pressure, so it can start the delivery operation without delay after the suction side communication maintenance control, shortening the time it takes for one operation, consisting of the suction operation and delivery operation caused by one reciprocating movement of the piston, known as the cycle time.

In the above configuration, the suction side open state maintenance control is a control that maintains a state in which the pump and the suction path are connected for a set communication time after the pump has completed suctioning the liquid from the tank, and the control device has a memory unit that stores information about various liquids that can be applied to the liquid supply device and the communication time for each liquid, and the suction side open state maintenance control can be configured to change the communication time depending on the liquid contained in the tank.

With a liquid supply device of this configuration, the pressure inside the pump before the discharge operation can be increased to the tank pressure without adding a sensor or the like, and switching from the suction operation to the discharge operation can be performed smoothly. With a liquid supply device of this configuration, the "connection time" of the suction side connected state maintenance control can be set to a predetermined value taking into account, for example, the viscosity of the liquid, and delays in starting the discharge operation can be effectively suppressed.

The above configuration may include a pressure adjusting device that adjusts the pressure in the tank to a pressure higher than atmospheric pressure and lower than the pressure in the pump when liquid is being discharged from the discharge path.

With a liquid supply device of this configuration, the pressure inside the tank is made higher than atmospheric pressure, so the pressure inside the pump after the suction side communication maintenance control is also increased, shortening the time until the discharge operation starts and the time until the discharge device starts discharging liquid.

In the above configuration, the control valve can be a switching valve that switches between a first state in which the suction passage is connected to the pump and the communication between the pump and the delivery passage is blocked, and a second state in which the suction passage is connected to the pump and the delivery passage is blocked, and the pump is connected to the delivery passage.

With a liquid supply device of this configuration, when the connection between the suction path and the pump is cut off after the suction side connection maintenance control, the pump and the delivery path are brought into communication, so that switching to the delivery operation can be performed smoothly. In addition, with a liquid supply device of this configuration, the control can be simplified compared to a configuration in which two control valves are provided in each of the suction path and the delivery path.

In the above configuration, the control valve is a solenoid valve, and can be configured to realize the first state in an energized state and the second state in a de-energized state.

When the liquid supply device of this configuration is switched from a powered state (ON state) to a non-powered state (OFF state), communication with the pump is switched from the intake path to the delivery path. In other words, the control valve, which is a solenoid valve, is generally mechanically switched from the first state to the second state by the biasing force of a spring or the like, so that switching to the delivery operation is performed smoothly and reliably.

The present invention provides a liquid supply device that can smoothly switch from the suction operation to the delivery operation, thereby avoiding delays in the supply of liquid.

FIG. 1 is a schematic diagram of a coating apparatus including a liquid supply device according to a first embodiment of the present invention. FIG. 2 is a side view of a drive unit included in the pump unit shown in FIG. 3 is a cross-sectional view of the switching valve shown in FIG. FIG. 4 is an enlarged view of a main part of FIG. 3 in a state in which electricity is not applied and the second state is shown; FIG. 4 is an enlarged view of a main part of FIG. 3 in a first state when power is applied; 2 is a timing chart showing control in the coating apparatus shown in FIG. 1. FIG. 1 is a schematic diagram of a coating apparatus including a liquid supply device according to a second embodiment of the present invention. Timing chart of control in the coating apparatus shown in FIG.

Below, several embodiments of the present invention will be described in detail with reference to the drawings as modes for carrying out the present invention. Note that the present invention is not limited to the following embodiments, and can be carried out in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

The liquid supply device 10 of the first embodiment of the present invention constitutes the coating device 12 shown in FIG. 1. The coating device 12 is mainly composed of the liquid supply device 10 of the first embodiment and a spray nozzle (discharge device) 14 that discharges the coating liquid as a liquid onto multiple coating objects. The liquid supply device 10 is capable of repeatedly supplying a fixed amount of coating liquid, and the coating device 12 is capable of repeatedly discharging a fixed amount of coating liquid from the spray nozzle 14, and can automatically and continuously coat multiple coating objects transported by a transport device, for example. The coating device 12 can be used, for example, to apply resist liquid as a coating liquid to semiconductor wafers, to apply various materials to glass substrates in the manufacturing process of liquid crystal devices, to apply release agents to mold forms, and to spray chemicals in experiments, etc.

As shown in FIG. 1, the liquid supply device 10 includes a tank 16 that stores the coating liquid at atmospheric pressure, a pump unit 18, an intake path 20 that connects the tank 16 and the pump unit 18 so that the pump unit 18 can draw in the coating liquid from the tank 16, and a delivery path 22 that connects the pump unit 18 and the spray nozzle 14 so that the pump unit 18 can deliver the coating liquid to the spray nozzle 14. The pump unit 18 includes a syringe pump 30, a drive unit 32 that serves as the drive source for the syringe pump 30, a switching valve (an example of a control valve) 34 that connects the syringe pump 30, the intake path 20, and the delivery path 22 and switches their communication states, and a control device 36 that controls the drive unit 32 and the switching valve 34, all assembled in a case 38.

The syringe pump 30 is composed of a cylindrical cylinder 40 and a piston 42 that can slide within the cylinder 40. The syringe pump 30 is extended and retracted by a drive unit 32. More specifically, the syringe pump 30 is fixed to the front surface of a case 38 with the cylinder 40 extending in the vertical direction, and the rod portion 42A of the piston 42 that extends downward from the cylinder 40 is moved in the vertical direction relative to the cylinder 40, thereby extending and retracting the syringe pump 30.

As shown in FIG. 2, the drive unit 32 is mainly composed of a motor 50 and a ball screw mechanism 52. The ball screw mechanism 52 consists of a screw rod 52A with a male screw and a nut 52B that screws onto the screw rod 52A. The screw rod 52A is held rotatably around its axis in a vertically extending position relative to the base 54, and its upper end is fixed to the motor shaft 50A of the motor 50. In other words, the screw rod 52A is rotated around its axis by the motor 50. On the other hand, the nut 52B is fixed to a slider 56 that is slidably arranged along the base 54. In other words, the nut 52B is prohibited from rotating around its own axis, and is moved up and down along the screw rod 52A when the screw rod 52A is rotated by the motor 50. In addition, since the slider 56 is fixed to the lower end of the rod portion 42A of the piston 42, the piston 42 can also be moved up and down by the vertical movement of the nut 52B. In this embodiment, the motor 50 is a stepping motor, and the rotation angle is controlled by controlling the number of pulses to control the position of the piston 42, and the speed of the piston 42 is controlled by controlling the pulse frequency. In addition, the drive unit 32 is provided with an origin position sensor 60 for detecting that the piston 42 is at the upper end position (origin position), which is the uppermost position, and a lower end position sensor 62 for detecting that the piston 42 is at the lowermost position. The origin position sensor 60 is for setting the origin position of the piston 42, that is, the origin position of the motor 50, when the liquid supply device 10 is started. In addition, the origin position sensor 60 and the downward end position sensor 62 also function as stoppers for the piston 42, and the piston 42 is designed to operate within the range detected by these sensors 60 and 62.

Next, the switching valve 34 will be described with reference to Figures 3 to 5. The switching valve 34 is a solenoid valve, and includes a housing 70, an electromagnet 72, a plunger 74 that is moved in its axial direction when the electromagnet 72 is excited, and a diaphragm valve 76. The diaphragm valve 76 is held within the housing 70 so as to be able to swing about a rotating shaft 76A. The housing 70 is provided with three ports 70A, 70B, and 70C. The first port 70A is connected to the intake passage 20, the second port 70B is connected to the syringe pump 30, and the third port 70C is connected to the delivery passage 22. As shown in Figure 4, when the first port 70A is closed by the diaphragm valve 76, the second port 70B and the third port 70C are communicated with each other, and the syringe pump 30 is in a state of communication with the delivery passage 22 and is in a state of being blocked from the intake passage 20. On the other hand, as shown in FIG. 5, when the third port 70C is closed by the diaphragm valve 76, the second port 70B and the first port 70A are connected to each other, and the syringe pump 30 is connected to the intake path 20 and is cut off from the delivery path 22.

A main pressing member 78 that presses one end 76B of the diaphragm valve 76 is fixed to the plunger 74 and is biased toward the diaphragm valve 76 (downward in FIG. 3) by a first coil spring 80. When the electromagnet 72 is excited, the plunger 74 and the main pressing member 78 are moved to the opposite side to the diaphragm valve 76 (upward in FIG. 3). The main pressing member 78 also includes a secondary pressing member 82 that presses the other end 76C of the diaphragm valve 76 and a second coil spring 84 that biases the secondary pressing member 82 toward the diaphragm valve 76 (downward in FIG. 3).

The biasing force of the first coil spring 80 is greater than the biasing force of the second coil spring 84. Therefore, when the electromagnet 72 is not excited (de-energized state, OFF state), as shown in FIG. 4, the main pressing member 78 presses one end 76B of the diaphragm valve 76 to block the first port 70A. In other words, a second state is realized in which the communication between the intake path 20 and the syringe pump 30 is blocked and the communication between the syringe pump 30 and the discharge path 22 is established. On the other hand, when the electromagnet 72 is excited (energized state, ON state), as shown in FIG. 5, the plunger 74 and the main pressing member 78 are pulled in, and the secondary pressing member 82 biased by the second coil spring 84 presses the other end 76C of the diaphragm valve 76 to swing the diaphragm valve 76. This closes the third port 70C and opens the first port 70A. In other words, the first state is achieved in which the intake path 20 and the syringe pump 30 are connected to each other and the syringe pump 30 and the delivery path 22 are disconnected from each other.

The liquid supplying device 10 configured as above is controlled by the control device 36. More specifically, the liquid supplying device 10 is capable of repeatedly supplying the coating liquid by controlling the switching valve 34 and the motor 50 by the control device 36. Specifically, the syringe pump 30 repeatedly performs an intake operation of suctioning the coating liquid from the tank 16 through the intake path 20 and an output operation of outputting the intake coating liquid to the spray nozzle 14 through the output path 22, thereby repeatedly supplying the coating liquid. The liquid supplying device 10 is capable of repeatedly supplying a fixed amount of coating liquid based on input information, and continuously supplying the coating liquid while a signal to discharge the coating liquid from the spray nozzle 14 is being output by an operation input. Below, the control when the liquid supplying device 10 repeatedly supplies a fixed amount of coating liquid will be described in detail with reference to the timing chart of FIG. 6.

In the application device 12 of this embodiment, when the pump unit 18 is turned on, an operation screen for inputting the amount of liquid discharged at one time (discharge amount), the number of times of discharge, the operating speed of the piston 42 of the syringe pump 30, information on the liquid to be discharged, etc. is displayed on the display device 24 shown in FIG. 1. Then, when the operator inputs these information and starts the operation of the pump unit 18, the suction operation is performed first. In the suction operation, the switching valve 34 is first turned on to realize a first state in which the suction path 20 and the syringe pump 30 are connected to each other and the communication between the syringe pump 30 and the discharge path 22 is blocked. Next, the pulse frequency to the motor 50 is determined based on the data input to the motor 50, and the control device 36 sends the signal to the driver of the motor 50 to move the piston 42 at a set speed and extend the syringe pump 30. In addition, in the first inhalation operation, an amount of liquid that exceeds the input amount of liquid discharged in one operation is inhaled, and thereafter, the movement amount (operation position) of the piston 42 is controlled so that the same amount of liquid as the amount discharged is inhaled. In other words, the rotation angle (number of pulses) of the motor 50 is controlled.

When the above suction operation is performed, the liquid pressure in the syringe pump 30 drops, as shown in Figure 6. If the switching valve 34 is turned OFF while the liquid pressure in the syringe pump 30 is in this lowered state, blocking communication between the suction path 20 and the syringe pump 30 and switching to a second state in which the syringe pump 30 is in communication with the delivery path 22, there is a problem that in the next delivery operation (discharge operation), the pressure difference until the liquid pressure at which the coating liquid is actually discharged from the spray nozzle 14 becomes large and the delivery operation does not start smoothly.

In the liquid supply device 10, when the piston 42 is moved to a target position and a set amount of application liquid is sucked in, the suction side communication state maintenance control is then executed. The suction side communication state maintenance control is a control that keeps the switching valve 34 in the ON state even after the motor 50 is stopped, so that the syringe pump 30 and the tank 16 continue to communicate with each other via the suction path 20. The suction side communication state maintenance control is performed only for the communication time T that is set according to the type of liquid, the viscosity of the liquid, etc.

The control device 36 is adapted to determine the communication time T based on data input by the operator. More specifically, the control device 36 has a storage unit 36A, which stores information on various liquids that can be applied to the liquid supply device 10, as well as the communication time T corresponding to the type of liquid and the viscosity of the liquid, such as the communication time T for each type of liquid and map data showing the relationship between the viscosity of the liquid and the communication time T, and the communication time T is determined from the data input by the operator while referring to the information stored in the storage unit 36A. This suction side communication state maintenance control is performed until the condition is reached where the pressure in the syringe pump 30 has risen to the pressure of the tank 16, and the above-mentioned communication time T is set based on a calculated value, a verified value, or the like, as the time required for the liquid pressure (atmospheric pressure) of the liquid contained in the tank 16 to rise to that of the liquid contained in the tank 16. For example, the communication time T can also be determined by multiplying the operating speed of the piston 42 (the rotational speed of the motor 50) by a coefficient.

When the communication time T has elapsed, the switching valve 34 is switched to the OFF state, blocking communication between the suction passage 20 and the syringe pump 30, and switching to a second state in which the syringe pump 30 is connected to the delivery passage 22. Thereafter, the control device 36 performs a delivery operation in response to a signal being sent to the spray nozzle 14 to perform application. In other words, the control device 36 sends a signal to the driver of the motor 50 with a pulse frequency and number of pulses determined based on the input data, moves the piston 42 at a set speed, and contracts the syringe pump 30. Then, when the first delivery operation is completed, the suction operation, the suction side communication state maintenance control, and the delivery operation are repeated as one cycle until the number of input cycles is reached.

As a result of the above configuration, when the liquid supply device 10 starts the discharge operation, the liquid pressure in the syringe pump 30 is increased to the liquid pressure in the tank 16 by the suction side communication state maintenance control, so that the delay from when the syringe pump 30 starts operating until the coating liquid is discharged from the spray nozzle 14 can be reduced, and switching from the suction operation to the discharge operation can be performed smoothly. In addition, because the liquid pressure in the syringe pump 30 is constant when the syringe pump 30 starts operating, the timing at which the coating liquid is actually discharged from the spray nozzle 14 can be stabilized, and the coating of the object to be coated can be performed without unevenness.

In addition, in the liquid supply device 10, the control valve for switching the communication state between the suction path 20 and the syringe pump 30 and the communication state between the syringe pump 30 and the delivery path 22 is a switching valve that switches between an energized state and a non-energized state to switch between (I) a first state in which the suction path 20 is connected to the syringe pump 30 and the communication between the syringe pump 30 and the delivery path 22 is blocked, and (II) a second state in which the communication between the suction path 20 and the syringe pump 30 is blocked and the syringe pump 30 is connected to the delivery path 22. The control valve may be configured with two valves provided in each of the suction path and the delivery path, but compared to that configuration, the liquid supply device 10 has a simpler configuration and is easier to control.

Next, the liquid supply device 100 of the second embodiment will be described with reference to FIG. 7 and FIG. 8. The liquid supply device 100 of the second embodiment has a similar configuration to the liquid supply device 10 of the first embodiment, and the same components as those of the first embodiment are given the same reference numerals, and their description may be simplified or omitted. The liquid supply device 100 of the second embodiment is the main component of the coating device 102 together with the spray nozzle 14, similar to the liquid supply device 10 of the first embodiment. Also, the liquid supply device 100 of the second embodiment is configured to include a tank 106, a pump unit 108, an intake path 20, and an outlet path 22, similar to the liquid supply device 10 of the first embodiment. However, the liquid supply device 100 of the second embodiment is provided with a pressure sensor 110 for detecting the internal liquid pressure in the syringe pump 30, and a pressurizing device 112 for pressurizing and adjusting the liquid pressure in the tank 106, as shown in FIG. 7.

Although there is no particular limitation on the pressurizing device 112, in this embodiment, the pressurizing device 112 pressurizes the liquid pressure of the coating liquid in the tank 106 by sending air into the tank 106, and adjusts the liquid pressure to a set pressure. The pressurizing device 112 adjusts the liquid pressure of the coating liquid in the tank 106 to a reference pressure _P0 that is higher than atmospheric pressure and lower than the pressure in the syringe pump 30 when the coating liquid is being sent out from the delivery path 22.

The liquid supply device 100 of the second embodiment thus configured has the same control method for the suction operation and the delivery operation as the liquid supply device 10 of the first embodiment, but due to the presence of the pressurizing device 112, the cycle time, which is the time from the start of the suction operation to the completion of the delivery operation, can be shortened, as will be described in detail later. In addition, the suction side communication state maintenance control in the liquid supply device 10 of the first embodiment is a control that maintains the state in which the pump and the suction path are connected for a communication time T determined according to the liquid contained in the tank 16, but is different from the suction side communication state maintenance control in the liquid supply device 100 of the second embodiment. The suction side communication state maintenance control in the liquid supply device 100 of the second embodiment is performed based on the detection result of the pressure sensor 110. Below, the control of the liquid supply device 100 of the second embodiment will be described with reference to the timing chart of FIG. 8.

In the coating device 102 of this embodiment, when the pump unit 108 is started by an operator or the like, the suction operation is first performed. In the suction operation, the switching valve 34 is first turned on to realize a first state in which the suction path 20 and the syringe pump 30 are connected and the communication between the syringe pump 30 and the delivery path 22 is blocked. Next, the motor 50 is controlled to move the piston 42 at a set speed and extend the syringe pump 30. As with the liquid supply device 10 of the first embodiment, in the first suction operation, the amount of liquid that is greater than the input amount of liquid discharged is sucked in, and thereafter, the movement amount (operation position) of the piston 42 is controlled so that the same amount of liquid as the amount of liquid discharged is sucked in.

When the above-mentioned suction operation is performed, the liquid pressure in the syringe pump 30 is reduced as shown in FIG. 8. However, in the liquid supplying device 100 of the second embodiment, the liquid pressure in the tank 106 is increased above atmospheric pressure by the pressurizing device 112, so the reduction in the liquid pressure in the syringe pump 30 is smaller than that in the liquid supplying device 10 of the first embodiment. Then, when the piston 42 is moved to a target position and a predetermined amount of coating liquid is sucked in, the suction side communication state maintenance control is executed. The suction side communication state maintenance control is a control that keeps the switching valve 34 in the ON state even after the motor 50 is stopped, and maintains the state in which the syringe pump 30 and the tank 16 are communicated via the suction path 20. The suction side communication state maintenance control is performed until the liquid pressure detected by the pressure sensor 110 becomes the liquid pressure in the tank 106, that is, the above-mentioned reference pressure P ₀ .

When the liquid pressure of the syringe pump 0 rises to the reference pressure _P0 , the switching valve 34 is turned OFF, the communication between the suction passage 20 and the syringe pump 30 is cut off, and the syringe pump 30 is switched to a second state in which the syringe pump 30 is connected to the delivery passage 22. Thereafter, the control device 36 performs a delivery operation in response to a signal sent to the spray nozzle 14 to perform application. At this time, since the pressure in the syringe pump 30 is raised to the reference pressure _P0 , the time until the pressure reaches a pressure at which the application liquid is discharged from the spray nozzle 14 is shortened compared to the first embodiment. Then, when the first delivery operation is completed, the suction operation, the suction side communication state maintenance control, and the delivery operation are repeatedly executed until the input number of times is reached.

As a result of the above configuration, the liquid supply device 100 of this embodiment does not waste time in the suction side open state maintenance control, and the suction side open state maintenance control is terminated based on the detection result of the pressure sensor 110, so the subsequent delivery operation can be started without delay. As described above, the time it takes to reach a pressure at which the coating liquid is discharged from the spray nozzle 14 is also shortened, and the cycle time, which is the time it takes for one operation to be performed, consisting of the suction operation and delivery operation caused by one reciprocating motion of the piston 42, is shortened.

In addition, since the liquid supply device 100 of this embodiment is capable of detecting the liquid pressure in the syringe pump 30 using the pressure sensor 110, even if a malfunction occurs in the drive unit or the like, it is possible to detect a malfunction of the liquid supply device 100 when underpressure or the like is detected.

<Other embodiments>
The present invention is not limited to the above-described embodiment, and can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. For example, the following embodiments are also included within the technical scope of the present invention.
(1) In the above embodiment, the pump is a syringe pump. However, a diaphragm-type pump may be used as long as the pump performs intake and discharge operations by the reciprocating motion of a piston.
(2) In the above embodiment, the control valve is a switching valve that switches between a first state in which the inlet passage is connected to the pump and the connection between the pump and the outlet passage is blocked, and a second state in which the connection between the suction passage and the pump is blocked and the pump and the outlet passage are connected. However, the present invention is not limited to this and may be composed of, for example, two controllable valves provided in each of the intake passage and the outlet passage.
(3) In the above embodiment, the liquid supply device is equipped with a spray nozzle as an ejection device and is a component of an application device such as one that applies a resist liquid as a coating liquid to a semiconductor wafer, one that applies various materials to a glass substrate in the manufacturing process of a liquid crystal device, or one that applies a release agent to a formwork, etc. However, the ejection device is not limited to this and can also be used in one that simply drips a chemical onto a number of test specimens.

10...liquid supply device, 12...applicator, 14...spray nozzle (discharge device), 16...tank, 18...pump unit (pump), 20...suction path, 22...delivery path, 30...syringe pump, 32...drive unit (drive source), 34...switching valve (control valve), 36...control device, 36A...storage unit, 40...cylinder, 42...piston, 50...motor, 100...liquid supply device, 102...applicator, 106...tank, 110...pressure sensor, 112...pressurizing device

Claims (6)

A liquid supplying device capable of repeatedly supplying liquid,
A tank for containing a liquid;
a pump having a piston and a drive source for driving the piston, the pump sucking liquid from the tank through a suction passage and delivering the sucked liquid through a delivery passage;
a control valve connected to the suction passage, the discharge passage, and the pump, and capable of switching a communication state between the suction passage and the pump and a communication state between the pump and the discharge passage;
a control device for controlling the pump and the control valve;
The control device is characterized in that after the pump has completed suction of liquid from the tank, the control valve executes suction side connection state maintenance control to maintain a state in which the pump and the suction path are connected until a condition is reached in which the pressure inside the pump has risen to the pressure of the tank. The liquid supply device includes a pressure sensor that detects a pressure inside the pump,
2. The liquid supply device according to claim 1, wherein the control device, during the suction side communication state maintenance control, blocks communication between the pump and the suction path when the pressure detected by the pressure sensor becomes equal to or higher than the pressure in the tank. the suction side communication state maintenance control is control for maintaining a state in which the pump and the suction path are communicated for a predetermined communication time after the pump has completed suction of the liquid from the tank,
The control device includes:
a storage unit that stores information about various liquids that can be applied to the liquid supply device and the communication time for each liquid;
2. The liquid supply device according to claim 1, wherein in the suction side communication state maintenance control, the communication time is variable depending on the amount of liquid contained in the tank. The liquid supply device according to any one of claims 1 to 3, further comprising a pressure adjusting device that adjusts the pressure in the tank to a pressure higher than atmospheric pressure and lower than the pressure in the pump when liquid is being discharged from the discharge path. The liquid supply device according to any one of claims 1 to 4, wherein the control valve is a switching valve that switches between a first state in which the suction passage is connected to the pump and the communication between the pump and the delivery passage is blocked, and a second state in which the suction passage is connected to the pump and the delivery passage is blocked. The liquid supply device according to claim 5, wherein the control valve is a solenoid valve that realizes the first state in an energized state and the second state in a de-energized state.

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