Liquid feeding system

Abstract

To prevent the occurrence of an abnormality in coating work carried out by a coating head in a liquid feeding system for feeding liquid to the coating head.SOLUTION: A liquid feeding system 12 feeds a liquid L to a coating head 11 for discharging liquid L to a workpiece W. The liquid feeding system 12 comprises: an upstream side tank 14 for storing the liquid L; and a flow path 15 that includes piping connected to the upstream side tank 14. The flow path 15 includes feed piping 16 through which the liquid L is fed to the upstream side tank 14, liquid feed piping 17 through which the liquid L of the upstream side tank 14 is fed to the downstream side which becomes a coating head 11 side, a pump 18 that feeds the liquid L of the upstream side tank 14 to the downstream side, an upstream side valve 21 positioned on the downstream side of the pump 18 to selectively switch between a work state where the liquid L is fed downstream and an upstream side return state where the liquid L is returned to the upstream side tank 14, and a filter device 20 provided in one or both of the feed piping 16 and the liquid feed piping 17 to remove a foreign object in the liquid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a liquid delivery system. [Background technology]

[0002] For example, a coating device disclosed in Patent Document 1 is used to discharge a liquid onto a workpiece such as glass or a film to form a film on the workpiece. The coating device has a coating head that discharges the liquid onto the workpiece and a liquid delivery system that supplies the liquid to the coating head. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-152036 Summary of the Invention [Problem to be solved by the invention]

[0004] A coating head discharges liquid onto a workpiece, forming a film on the workpiece. It is desirable for the thickness of this film to be as uniform as possible. The quality of the film has a significant impact on the product manufactured from the workpiece. For this reason, various efforts are being made to improve the liquid delivery system that supplies the liquid to the coating head, in order to prevent abnormalities from occurring during the coating operation by the coating head.

[0005] Therefore, an object of the present invention is to prevent abnormalities from occurring in the coating operation by the coating head in a liquid delivery system that supplies liquid to the coating head. [Means for solving the problem]

[0006] The liquid delivery system of the present invention supplies liquid to a coating head that discharges the liquid onto a workpiece, and includes an upstream tank that stores the liquid, and a flow path including piping connected to the upstream tank. The flow path includes a liquid delivery piping that delivers the liquid from the upstream tank to the downstream side (the side of the coating head), a pump that delivers the liquid from the upstream tank to the downstream side, an upstream valve located downstream of the pump that switches between an operating state in which the liquid flows downstream and an upstream return state in which the liquid is returned to the upstream tank, and a filter device provided in the liquid delivery piping to remove foreign matter from the liquid.

[0007] The liquid delivery system of the present invention supplies liquid to a coating head that discharges liquid onto a workpiece, and includes an upstream tank that stores liquid and a flow path including piping connected to the upstream tank. The flow path includes a supply pipe that supplies liquid to the upstream tank, a liquid delivery pipe that delivers the liquid from the upstream tank downstream to the coating head, a pump that delivers the liquid from the upstream tank downstream, an upstream valve located downstream of the pump that switches between an operating state in which the liquid flows downstream and an upstream return state in which the liquid is returned to the upstream tank, and a filter device located in the supply pipe for removing foreign matter from the liquid. [Effects of the Invention]

[0008] According to the liquid delivery system of the present invention, it is possible to suppress coating abnormalities. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the configuration of an example of a coating apparatus having a liquid delivery system of the present invention. [Figure 2] FIG. 2 is a configuration diagram of a coating apparatus showing another embodiment of a liquid delivery system. [Figure 3] FIG. 3 is a configuration diagram of a coating apparatus showing still another embodiment of the liquid delivery system. [Figure 4] FIG. 4 is a configuration diagram of a coating apparatus showing still another embodiment of the liquid delivery system. [Figure 5] FIG. 5 is an explanatory diagram showing a modified example of the filter device. [Figure 6] FIG. 6 is a configuration diagram of a coating apparatus showing still another embodiment of the liquid delivery system. [Figure 7] FIG. 7 is a configuration diagram of a coating apparatus showing still another embodiment of the liquid delivery system. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Outline of the embodiment of the present invention> Hereinafter, an outline of an embodiment of the present invention will be listed and described. (1) The liquid delivery system of the present invention is a liquid delivery system that supplies liquid to an application head that ejects liquid onto a workpiece, and includes an upstream tank that stores liquid, and a flow path section including piping connected to the upstream tank. The flow path section includes a liquid delivery piping that delivers the liquid from the upstream tank to the downstream side, which is the application head side, a pump that delivers the liquid from the upstream tank to the downstream side, an upstream valve located downstream of the pump that switches between an operating state in which the liquid flows downstream and an upstream return state in which the liquid is returned to the upstream tank, and a filter device provided in the liquid delivery piping to remove foreign matter from the liquid.

[0011] When the upstream valve is in the working state, the liquid is sent downstream, allowing the coating head to perform the coating operation. When the upstream valve is in the return state, the liquid is returned to the upstream tank, allowing the liquid in the upstream tank to circulate. The liquid sent from the upstream tank to the coating head passes through a filter device, which removes foreign matter from the liquid, making it possible to prevent coating defects caused by foreign matter.

[0012] (2) In the liquid delivery system of (1), the filter device is provided downstream of the pump in the liquid delivery pipe, and the liquid delivered from the pump passes through the filter device. The liquid sent from the upstream tank to the application head passes through a filter device to remove foreign matter contained in the liquid. Even if foreign matter is generated due to peeling of the surface of a component constituting the pump and gets mixed into the liquid, the filter device, located downstream of the pump, can remove the foreign matter.

[0013] (3) In the liquid transfer system of (2), the filter device is provided between the pump and the upstream valve. Even when the upstream valve is in the upstream return state and the liquid is returned to the upstream tank, the liquid passes through the filter device during circulation, and foreign matter contained in the liquid is removed.

[0014] (4) In the liquid delivery system of (1), the liquid delivery pipe has a working pipe connected to the downstream side of the upstream valve, and the filter device is provided in the working pipe. When the upstream valve is in the working state, the liquid is sent to the downstream working pipe and passes through the filter device. When the upstream valve is in the return state, the liquid is returned to the upstream tank and does not pass through the filter device. This reduces the number of times the liquid passes through the filter device.

[0015] (5) The liquid delivery system of the present invention is a liquid delivery system that supplies liquid to an application head that ejects liquid onto a workpiece, and includes an upstream tank that stores liquid, and a flow path section including piping connected to the upstream tank. The flow path section includes a supply piping that supplies liquid to the upstream tank, a liquid delivery piping that delivers the liquid from the upstream tank downstream to the application head, a pump that delivers the liquid from the upstream tank downstream, an upstream valve located downstream of the pump that switches between an operating state in which the liquid flows downstream and an upstream return state in which the liquid is returned to the upstream tank, and a filter device provided in the supply piping to remove foreign matter from the liquid.

[0016] When the upstream valve is in the working state, the liquid is sent downstream, allowing the coating head to perform the coating operation. When the upstream valve is in the return state, the liquid is returned to the upstream tank, allowing the liquid in the upstream tank to circulate. The liquid supplied to the upstream tank passes through a filter device to remove foreign matter contained in the liquid. In other words, the liquid from which foreign matter has been removed by passing through the filter device is supplied to the upstream tank. As a result, coating abnormalities caused by foreign matter can be suppressed.

[0017] (6) In any one of the liquid delivery systems (1) to (5), the filter device includes a branching section through which the liquid passes, a first branch flow path and a second branch flow path that branch off from the branching section and are parallel to each other, a valve for selectively flowing the liquid into one of the first branch flow path and the second branch flow path, a confluence section where the first branch flow path and the second branch flow path converge, a first filter provided in the first branch flow path, and a second filter provided in the second branch flow path. When the second filter needs maintenance, the first filter is used, and when the first filter needs maintenance, the second filter is used. In other words, even when filter maintenance is required, there is no need to stop the liquid delivery.

[0018] (7) The temperature of the liquid affects the thickness of the coating of the liquid discharged from the coating head. Therefore, the liquid delivery system of any one of (1) to (6) further includes a sensor for measuring the temperature of the liquid, and switches the upstream valve to the upstream return state when the temperature of the liquid is out of range. If the liquid temperature is out of range, the liquid is returned to the upstream tank, which makes it possible to prevent coating abnormalities caused by liquid temperature errors.

[0019] (8) In any one of the liquid delivery systems (1) to (7), a liquid temperature adjustment device is provided for adjusting the temperature of one or both of the liquid stored in the upstream tank and the liquid in the liquid delivery pipe.

[0020] (9) In the liquid delivery system of (8), the upstream tank has a tank body for storing liquid and a jacket provided on the outside of the tank body and constituting a first temperature control flow path through which a heat medium passes between the tank body and the jacket, and the liquid temperature adjustment device has a temperature control pipe for supplying a heat medium to the first temperature control flow path. Heat is exchanged between the heat medium passing through the first temperature control flow path formed between the tank body and the jacket and the liquid in the tank body. The temperature of the liquid in the tank body is adjusted. For example, if the temperature of the liquid in the tank body is high, the liquid is cooled by the heat medium.

[0021] (10) In the liquid delivery system of (9), the liquid delivery piping has a temperature control section located downstream of the pump and through which the liquid passes, the temperature control section has an inner member having a flow path therein through which the liquid passes, and an outer member provided outside the inner member and constituting a second temperature control flow path through which a heat medium passes between the inner member and the outer member, and the liquid temperature adjustment device has a temperature control piping for supplying a heat medium to the second temperature control flow path. Heat is exchanged between the heat medium passing through the second temperature control flow path formed between the inner member and the outer member and the liquid passing through the inside of the inner member. Even if the temperature of the liquid increases as the liquid passes through the pump, the liquid is cooled in the temperature control unit.

[0022] (11) In the liquid transfer system of (10), the liquid temperature adjustment device includes a circulation flow path through which the heat medium flows, and a cooler that is provided in the circulation flow path and cools the heat medium, The circulation flow path has a flow path configuration in which the heat medium cooled by the cooler passes through the second temperature control flow path, and the heat medium that has passed through the second temperature control flow path passes through the first temperature control flow path. The liquid in the upstream tank is pumped out by a pump and passes through the temperature control unit. The heat medium cooled by the cooler is supplied to the second temperature control flow path on the temperature control unit side before being supplied to the first temperature control flow path on the upstream tank side. This makes it easier to adjust the temperature of the liquid sent to the application head side to a desired temperature, resulting in high temperature control efficiency.

[0023] (12) Any one of the liquid delivery systems (1) to (11) has a primary unit including the upstream tank, the pump, the upstream valve, and the filter device, and has, as secondary units, an intermediate tank that stores the liquid delivered from the upstream valve in the working state, and a downstream valve located downstream of the intermediate tank that selectively switches between a coating state in which the liquid flows toward the coating head and an intermediate return state in which the liquid is returned to the intermediate tank. Even if a part of the primary unit stops operating, for example, for maintenance, the liquid stored in the intermediate tank can be used to perform the coating operation by the coating head. When the downstream valve is in the application state, the liquid is supplied to the application head and the liquid is applied to the workpiece, and when the downstream valve is in the intermediate return state, the application operation is stopped.

[0024] (13) The liquid delivery system of (12) has a plurality of the primary units. In one primary unit, if the filter device is undergoing maintenance, for example, or if the liquid temperature is outside the appropriate range, liquid will not be supplied to the intermediate tank, but in that case liquid can still be supplied from another primary unit.

[0025] <Details of the embodiment of the present invention> Hereinafter, the details of the embodiments of the present invention will be described. [Overall configuration of coating device] 1 is a structural diagram showing an example of a coating apparatus having a liquid delivery system of the present invention. The coating apparatus 10 has a coating head 11 that ejects liquid L onto a workpiece W, and a liquid delivery system 12 that supplies liquid L to the coating head 11. The workpiece W may be a single substrate or a continuous sheet.

[0026] The coating head 11 has a shape that is long in one direction. The coating head 11 has an internal space 112 and a slit 111 that are provided along its longitudinal direction. The liquid L supplied to the coating head 11 enters the internal space 112, is discharged from the slit 111, and is applied to the workpiece W. The coating head 11 and the workpiece W move relative to each other by a transport device (not shown). As the head 11 moves, the liquid L is discharged and a film is formed on the substrate W. This operation is the coating operation (coating operation).

[0027] [Liquid delivery system 12(1)] The liquid delivery system 12 shown in FIG. 1 includes an upstream tank 14 that stores a liquid L, and a flow path section 15 that includes a pipe connected to the upstream tank 14. The upstream tank 14 has an agitating blade 143 that agitates the liquid L by being rotated by a motor.

[0028] The flow path section 15 has a supply pipe 16 and a liquid delivery pipe 17 connected to the upstream tank 14. The supply pipe 16 is a pipe for supplying the liquid L from the liquid supply unit 13 located at the most upstream side to the upstream tank 14. The liquid delivery pipe 17 is a pipe for delivering the liquid L from the upstream tank 14 to the downstream side, which is the application head 11 side. Regarding the flow direction of the liquid L in the liquid delivery system 12, the liquid supply unit 13 side is the "upstream side", and the application head 11 side is the "downstream side".

[0029] The flow path section 15 includes a pump 18 , a filter device 20 , and an upstream valve 21 . The pump 18 is provided in the middle of the liquid delivery pipe 17 near the upstream side, and delivers the liquid L from the upstream tank 14 downstream.

[0030] The filter device 20 removes foreign matter from the liquid. In the case of the liquid delivery system 12 shown in FIG. 1, the filter device 20 is provided in the middle of the liquid delivery pipe 17. The filter device 20 is provided between the pump 18 and the upstream valve 21. The liquid L delivered from the pump 18 passes through the filter device 20.

[0031] The filter device 20 has a filter 201 having a micro flow path therein, as well as a magnetic filter 202. One or more filters 201 may be provided, and the filter device 20 shown in Fig. 1 has two filters 201. The second filter 201 on the downstream side is more impervious to small foreign matter than the first filter 201 on the upstream side.

[0032] The upstream valve 21 is located downstream of the pump 18 and the filter device 20. The liquid supply pipe 17 is connected to a first port 211 of the upstream valve 21 on its downstream side (midway on the downstream side). The upstream valve 21 shown in Figure 1 is a three-way valve. The flow path section 15 has an upstream return pipe 151 connected to the second port 212 of the upstream valve 21, and a working pipe 152 connected to the third port 213 of the upstream valve 21. The working pipe 152 is part of the liquid delivery pipe 17. The upstream return pipe 151 is a pipe that connects the upstream valve 21 to the upstream tank 14. The upstream return pipe 151 is connected to the upstream tank 14 at a position higher than the liquid level of the liquid L stored in the upstream tank 14. With this configuration, when the liquid L flows out from the upstream return pipe 151 to the upstream tank 14, air bubbles are easily removed from the liquid L. The working pipe 152 is a pipe that extends from the upstream valve 21 to the downstream side, which is the coating head 11 side.

[0033] The upstream valve 21 selectively switches between an operating state in which the liquid L flows downstream and an upstream return state in which the liquid L is returned to the upstream tank 14. In other words, when the opening / closing state of the valve element of the upstream valve 21 becomes a first state, the upstream valve 21 enters an operating state in which the liquid L flows through the working pipe 152 to the downstream coating head 11. When the opening / closing state of the valve element of the upstream valve 21 becomes a second state, the upstream valve 21 enters an upstream return state in which the liquid L is returned to the upstream tank 14 through the upstream return pipe 151.

[0034] When the upstream valve 21 is in the operating state, the liquid L is supplied to the coating head 11, allowing the coating operation to be performed. When the upstream valve 21 is in the upstream return state, the liquid L is not supplied to the coating head 11, and the coating operation is stopped. The start and stop of coating are controlled by the operation of the upstream valve 21.

[0035] The liquid delivery system 12 has a temperature sensor 23 that measures the temperature of the liquid L flowing through the liquid delivery pipe 17. The temperature sensor 23 is provided upstream of the upstream valve 21. A control device 48 included in the liquid delivery system 12 controls the upstream valve 21 based on a signal from the temperature sensor 23. In this control, the open / close state of the upstream valve 21 is switched depending on the temperature measured by the temperature sensor 23. Management information related to the temperature of the liquid L is stored in the control device 48.

[0036] If the temperature of the liquid L measured by the temperature sensor 23 is outside the desired range indicated by the management information, the upstream valve 21 is switched to the upstream return state. As a result, the liquid L flowing through the liquid supply pipe 17 is returned to the upstream tank 14 through the upstream return pipe 151. If the temperature of the liquid L is abnormal, it is possible to prevent the application work from being performed. The liquid L circulates through the liquid supply pipe 17 and the upstream return pipe 151. When the temperature of the liquid L is within the desired range indicated by the management information, the upstream valve 21 is switched to the working state. As a result, the liquid L flowing through the liquid delivery pipe 17 is supplied to the coating head 11 through the working pipe 152. This makes it possible to carry out the coating operation.

[0037] The liquid delivery system 12 has a liquid temperature adjustment device 22. The liquid temperature adjustment device 22 is a device for adjusting the temperature of one or both of the liquid L stored in the upstream tank 14 and the liquid L in the liquid delivery pipe 17. In the case of the embodiment shown in Fig. 1, the temperatures of both the liquid L in the upstream tank 14 and the liquid L flowing through the liquid delivery pipe 17 are adjusted. The liquid temperature adjustment device 22 has a circulation flow path 221 through which a heat medium (refrigerant) F flows, and a cooler 222 that is provided midway along the circulation flow path 221 and cools the heat medium F. The cooler 22 cools the heat medium F to a temperature lower than the temperature of the surrounding environment.

[0038] 1 includes a tank body 141 that stores the liquid L, and a jacket 142 that is provided on the outside of the tank body 141. The upstream tank 14 has a double structure consisting of the inner tank body 141 and the outer jacket 142. The jacket 142 forms a first temperature control flow path 24 between the tank body 141 and the jacket 142, through which a heat medium F passes. The liquid L stored in the tank body 141 exchanges heat with the heat medium F in the first temperature control flow path 24.

[0039] The liquid supply pipe 17 shown in Fig. 1 has a temperature adjustment unit 19. The temperature adjustment unit 19 is located downstream of the pump 18, and the liquid L passes through it. The temperature adjustment unit 19 has an inner member 191 having an internal flow path through which the liquid L passes, and an outer member 192 provided on the outside of the inner member 191. The temperature adjustment unit 19 has a double-pipe structure made up of the inner member 191 and the outer member 192. The outer member 192 forms a second temperature adjustment flow path 25 between the inner member 191 and the outer member 192, through which the heat medium F passes.

[0040] In the embodiment shown in Fig. 1, two units each consisting of an inner member 191 and an outer member 192 are arranged in series. However, the number of units may be one. An agitator 193 is provided inside the inner member 191. The agitator 193 has a shape in which a plate-like member is twisted spirally. The liquid L passing through the inner member 191 exchanges heat with the heat medium F of the second temperature control flow path 25, and is agitated by flowing along the agitator 193.

[0041] The circulation flow path 221 of the liquid temperature adjustment device 22 has a flow path configuration in which the heat medium F cooled by the cooler 222 passes through the second temperature control flow path 25, and the heat medium F that has passed through the second temperature control flow path 25 passes through the first temperature control flow path 24. The liquid temperature adjustment device 22 has, as part of the circulation flow path 221, a temperature adjustment pipe 223 for supplying the heat medium F to the second temperature adjustment flow path 25. The liquid temperature adjustment device 22 has, as another part of the circulation flow path 221, a temperature adjustment pipe 224 for supplying the heat medium F to the first temperature adjustment flow path 24.

[0042] The liquid supply pipe 17 has two pressure sensors 26A, 26B that measure the pressure of the liquid L. The first pressure sensor 26A is located upstream of the filter device 20 and monitors clogging in the filter device 20. If the pressure (measured value) measured by the pressure sensor 26A exceeds a threshold value, maintenance (including replacement) of the filter device 20 is performed. The second pressure sensor 26B is located upstream of the upstream valve 21 and monitors the pressure of the liquid L supplied to the application head 11.

[0043] Here, when the upstream valve 21 is in the operating state, the liquid L in the upstream valve 21 is supplied to the coating head 11. In the coating head 11, the liquid L passes through the slit 111, so the flow path resistance becomes high, and the pressure (internal pressure) of the liquid L in the upstream valve 21 is relatively high.

[0044] On the other hand, when the upstream valve 21 is in the upstream return state, the liquid L in the upstream valve 21 is not supplied to the application head 11. Therefore, the flow path resistance is lower than in the working state, and the pressure of the liquid L in the upstream valve 21 is relatively lower (than in the working state).

[0045] Then, when the upstream valve 21 is switched from the upstream return state to the working state, the pressure difference before and after the switch is large, and even when the working state is reached, it may not be possible to quickly ensure the pressure of the liquid L in the coating head 11. This may result in a delay in the coating operation, a thin film thickness, etc.

[0046] Therefore, the upstream return pipe 151 has a pressure adjustment valve 27. The pressure adjustment valve 27 functions as a throttle and applies pressure to the liquid L flowing through the upstream valve 21 (second port 212). As a result, even when the upstream valve 21 is in the upstream return state, the pressure of the liquid L in the upstream valve 21 can be increased to the same level as when the upstream valve 21 is in the working state. Therefore, when the upstream valve 21 is switched from the upstream return state to the working state, delays in the coating operation and thinning of the film thickness can be suppressed.

[0047] [Liquid delivery system 12(2)] Fig. 2 is a configuration diagram of the coating apparatus 10 showing another embodiment of the liquid delivery system 12. The same components in the coating apparatus 10 shown in Fig. 2 and the coating apparatus 10 shown in Fig. 1 are denoted by the same reference numerals, and their description will be omitted. 2, in the liquid delivery system 12, the temperature of the liquid L is controlled in the liquid supply unit 13 on the upstream side, and foreign matter is removed from the liquid L. Such liquid L is supplied to the upstream tank 14.

[0048] 2 does not have a means for adjusting the temperature of the liquid L, as compared with the liquid delivery system 12 shown in Fig. 1. That is, the liquid delivery system 12 shown in Fig. 2 does not have a liquid temperature adjustment device 22, the upstream tank 14 does not have a first temperature adjustment flow path 24 for the heat medium F, and the liquid delivery pipe 17 does not have a temperature adjustment unit 19.

[0049] 2, foreign matter may be generated by the pump 18, and in order to remove the foreign matter even in such a case, the liquid delivery system 12 includes a filter device 20. The filter device 20 includes one filter 201 having a microchannel therein. In order to check the temperature of the liquid L, a temperature sensor 23 is provided in each of the upstream tank 14 and the liquid supply pipe 17.

[0050] [Liquid delivery system 12(3)] Fig. 3 is a configuration diagram of the coating apparatus 10 showing yet another embodiment of the liquid delivery system 12. The liquid delivery system 12 shown in Fig. 3 is a modified example of the liquid delivery system 12 shown in Fig. 2, and differs in the configuration of the supply pipe 16 for supplying the liquid L to the upstream tank 14. The same components in the coating apparatus 10 shown in FIG. 3 and the coating apparatus 10 shown in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof will be omitted.

[0051] The liquid delivery system 12 shown in Fig. 3 is different from the liquid delivery system 12 shown in Fig. 2 in terms of the filter device 20. The filter device 20 shown in Fig. 3 is the same as the filter device 20 shown in Fig. 1 and has three filters. The filter device 20 is provided midway along the supply pipe 16. The liquid L supplied from the liquid supply unit 13 to the upstream tank 14 passes through the filter device 20. The liquid L from which foreign matter has been removed by passing through the filter device 20 is supplied to the upstream tank 14.

[0052] [Liquid delivery system 12(4)] Fig. 4 is a configuration diagram of the coating device 10 showing yet another embodiment of the liquid delivery system 12. The coating head 11 shown in Fig. 4 is the same as the coating head 11 shown in Fig. 1. The liquid delivery system 12 shown in Fig. 4 has a primary unit U1 and a secondary unit U2. The primary unit U1 is similar to the liquid delivery system 12 shown in Fig. 1. That is, the liquid delivery system 12 shown in Fig. 4 has the liquid delivery system 12 shown in Fig. 1 as the primary unit U1. Specifically, the liquid delivery system 12 shown in Fig. 4 has the primary unit U1 including an upstream tank 14, a pump 18, an upstream valve 21, a filter device 20, etc.

[0053] The same components of the primary unit U1 shown in Fig. 4 and the liquid delivery system 12 shown in Fig. 1 are denoted by the same reference numerals, and the description thereof will be omitted. In the liquid delivery system 12 shown in Fig. 4, the liquid delivery piping 17 and the pump 18 included in the primary unit U1 are referred to as the "primary side liquid delivery piping 17" and the "primary side pump 18."

[0054] In the case of the liquid supply piping 17 shown in Fig. 1, the working piping 152 extending from the upstream valve 21 to the downstream side is connected to the coating head 11. In contrast, in the case of the liquid supply system 12 shown in Fig. 4, the working piping 152 extending from the upstream valve 21 to the downstream side is connected to the secondary unit U2. The secondary unit U2 has an intermediate tank 51, and the working piping 152 is connected to the intermediate tank 51. Since the working pipe 152 is connected to the secondary unit U2 (intermediate tank 51), the function of the upstream valve 21 will be described next.

[0055] The upstream valve 21 selectively switches between an operating state in which the liquid L flows downstream and an upstream return state in which the liquid L is returned to the upstream tank 14. In other words, when the opening / closing state of the valve element of the upstream valve 21 is in the first state, the upstream valve 21 enters the operating state in which the liquid L flows to the downstream intermediate tank 51 through the operating piping 152. When the opening / closing state of the valve element of the upstream valve 21 is in the second state, the upstream valve 21 enters the upstream return state in which the liquid L is returned to the upstream tank 14 through the upstream return piping 151.

[0056] When the upstream valve 21 is in the operating state, the liquid L is supplied to the intermediate tank 51, and the liquid L stored in the intermediate tank 51 is used, enabling the coating head 11 to perform the coating operation. When the upstream valve 21 is in the upstream return state, the liquid L is not supplied to the intermediate tank 51. However, even in this case, the liquid L stored in the intermediate tank 51 is used, enabling the coating head 11 to perform the coating operation. In other words, even when the upstream valve 21 is in the upstream return state, this does not affect the coating operation by the coating head 11. Because the secondary unit U2 functions, the coating operation is not stopped and remains possible.

[0057] [Secondary unit U2] The configuration of the secondary unit U2 will be described. The secondary unit U2 has a secondary-side liquid supply pipe 57 as a pipe included in the flow path section 15. The secondary-side liquid supply pipe 57 is connected to the intermediate tank 51, and supplies the liquid L from the intermediate tank 51 to the downstream side, which is the application head 11 side. The liquid supply system 12 has the intermediate tank 51, a secondary-side pump 52, and a downstream-side valve 54 as the secondary unit U2.

[0058] The intermediate tank 51 stores the liquid L sent from the upstream valve 21 in the operating state. The intermediate tank 51 has an agitating blade 511 that agitates the liquid L by rotating with a motor. The secondary pump 52 is provided in the middle of the secondary liquid supply pipe 57 near the upstream side, and supplies the liquid L in the intermediate tank 51 to the application head 11. The amount of liquid supplied by the primary pump 18 is greater than the amount of liquid supplied by the secondary pump 52.

[0059] The downstream valve 54 is located downstream of the intermediate tank 51 and further downstream of the secondary pump 52. The downstream side of the secondary liquid delivery pipe 57 is connected to a first port 541 of the downstream valve 54. The downstream valve 54 shown in Fig. 4 is a three-way valve.

[0060] In the secondary unit U2, the flow path section 15 has an intermediate return pipe 153 connected to a second port 542 of the downstream valve 54, and a coating pipe 154 connected to a third port 543 of the downstream valve 54. The intermediate return pipe 153 is a pipe that connects from the downstream valve 54 to the intermediate tank 51. The coating pipe 154 is a pipe that extends from the downstream valve 54 to the downstream side, which is the coating head 11 side.

[0061] The downstream valve 54 selectively switches between a coating state in which the liquid L flows toward the coating head 11 and an intermediate return state in which the liquid L is returned to the intermediate tank 51. In other words, when the opening / closing state of the valve body of the downstream valve 54 becomes a first state, the coating state is established in which the liquid L flows to the downstream coating head 11 through the coating piping 154. When the opening / closing state of the valve body of the downstream valve 54 becomes a second state, the intermediate return state is established in which the liquid L is returned to the intermediate tank 51 through the intermediate return piping 153.

[0062] When the downstream valve 54 is in the coating state, the liquid L is supplied to the coating head 11 and the coating operation is performed. When the downstream valve 54 is in the intermediate return state, the liquid L is not supplied to the coating head 11 and the coating operation is stopped. The start and stop of coating are controlled by the operation of the downstream valve 54. The downstream valve 54 is controlled by the control device 48 of the liquid delivery system 12.

[0063] The secondary liquid supply pipe 57 has a pressure sensor 58 that measures the pressure of the liquid L. The pressure sensor 58 is located upstream of the downstream valve 54 and monitors the pressure of the liquid L supplied to the coating head 11.

[0064] Here, when the downstream valve 54 is in the coating state, the liquid L in the downstream valve 54 is supplied to the coating head 11. In the coating head 11, the liquid L passes through the slit 111, so the flow path resistance becomes high, and the pressure (internal pressure) of the liquid L in the downstream valve 54 is relatively high.

[0065] On the other hand, when the downstream valve 54 is in the intermediate return state, the liquid L in the downstream valve 54 is not supplied to the application head 11. Therefore, the flow path resistance is lower than in the application state, and the pressure of the liquid L in the downstream valve 54 is relatively lower (than in the application state).

[0066] Then, when the downstream valve 54 is switched from the intermediate return state to the application state, the pressure difference before and after the switch is large, and even when the application state is reached, it may not be possible to quickly ensure the pressure of the liquid L in the application head 11. This may result in a delay in the application work, a thin film thickness, or the like.

[0067] Therefore, the intermediate return pipe 153 has a pressure adjustment valve 59. The pressure adjustment valve 59 functions as a throttle and applies pressure to the liquid L flowing through the downstream valve 54 (second port 542). As a result, even when the downstream valve 54 is in the intermediate return state, the pressure of the liquid L in the downstream valve 54 can be increased to the same level as when the downstream valve 54 is in the application state. Therefore, when the downstream valve 54 is switched from the intermediate return state to the application state, delays in the application operation and thinning of the film thickness are suppressed.

[0068] 4, foreign matter is removed from the liquid L by the filter device 20 of the primary unit U1, but the flow path section 15 has a filter 53 in the secondary unit U2. Even if foreign matter is generated in the pump 52, the foreign matter is removed by the filter 53. In addition, aggregates generated in the intermediate tank 51 are removed by the filter 53.

[0069] In the case of the liquid delivery system 12 shown in Fig. 4, in the primary unit U1 provided upstream of the secondary unit U2, the temperature of the liquid L is controlled by a liquid temperature adjusting device 22 or the like, and foreign matter is also removed from the liquid L by a filter device 20. Such liquid L is supplied to an intermediate tank 51 of the secondary unit U2.

[0070] 4, the secondary unit U2 does not have a means for adjusting the temperature of the liquid L. That is, the secondary unit U2 does not have the liquid temperature adjustment device 22 and the temperature adjustment section 19 that the primary unit U1 has. Moreover, the intermediate tank 51 does not have the first temperature adjustment flow path 24 for the heat medium F like the upstream tank 14. However, in the secondary unit U2, in order to check the temperature of the liquid L, a temperature sensor 60 is provided in each of the intermediate tank 51 and the secondary side liquid transfer pipe 57.

[0071] Fig. 6 is a configuration diagram of a coating apparatus showing yet another embodiment of the liquid delivery system 12. The liquid delivery system 12 shown in Fig. 6 is a modified example of the liquid delivery system 12 shown in Fig. 4, and differs in the arrangement of the filter device 20. The same components in the coating apparatus 10 shown in Fig. 6 and the coating apparatus 10 shown in Fig. 4 are denoted by the same reference numerals, and their description will be omitted.

[0072] The working pipe 211 connected to the downstream side of the upstream valve 21 is included in the liquid supply pipe 17 that supplies the liquid L from the upstream tank 14 to the downstream side, which is the application head 11 side. In the case of the liquid delivery system 12 shown in FIG. 6, the liquid L whose temperature has been adjusted by the liquid temperature adjustment device 22 passes through the filter device 20. In other words, the liquid L that has not reached the desired temperature at the upstream valve 21 (temperature sensor 23) flows through the upstream return pipe 151 and does not pass through the filter device 20. The liquid L that has reached the desired temperature at the upstream valve 21 (temperature sensor 23) flows through the working pipe 211 and passes through the filter device 20. This reduces the number of times the liquid L passes through the filter device 20, making it possible to extend the life of the filter device 20.

[0073] Fig. 7 is a configuration diagram of a coating apparatus showing yet another embodiment of the liquid delivery system 12. The liquid delivery system 12 shown in Fig. 7 is a modified example of the liquid delivery system 12 shown in Fig. 4, and differs in the number of primary units U1. The same components in the coating apparatus 10 shown in Fig. 7 and the coating apparatus 10 shown in Fig. 4 are denoted by the same reference numerals, and their description will be omitted. The liquid delivery system 12 shown in Fig. 7 has a plurality of primary units U1. In the illustrated example, three primary units U1 are provided, but the number can be changed as long as it is two or more. In Fig. 7, the reference numerals of the components included in some of the primary units U1 (the second and third from the top) are omitted due to space limitations in the drawing, but these primary units U1 each have the same configuration.

[0074] Since the liquid delivery system 12 has multiple primary units U1, for example, when maintenance of the filter device 20 is being performed in one primary unit U1 or when the temperature of the liquid L is outside the appropriate range, the liquid L is not supplied to the intermediate tank 51, but even in such cases, it is possible to supply the liquid L from another primary unit U1. This makes it possible to replenish the intermediate tank 51 with the liquid L, and to continue the coating operation.

[0075] [Modification of the filter device 20] Fig. 5 is an explanatory diagram showing a modified example of the filter device 20. The filter device 20 shown in Fig. 5 is applicable to the filter device 20 of the liquid delivery system 12 of each of the above-described embodiments. The filter device 20 shown in Figure 5 has a branching section 70 through which liquid L passes, a first branch flow path 71 and a second branch flow path 72 that branch off from the branching section 70 and run in parallel, a first valve 73, a junction section 74 where the first branch flow path 71 and the second branch flow path 72 join together, a first filter 75 provided midway along the first branch flow path 71, and a second filter 76 provided midway along the second branch flow path 72.

[0076] The first valve 73 is a valve for selectively flowing the liquid L into one of the first branch flow path 71 and the second branch flow path 72. The first valve 73 is provided at the branching portion 70, and in the case of the filter device 20 shown in Fig. 5, is a three-way valve. The filter device 20 has a second valve 77 provided at the confluence portion 74.

[0077] When the open / close state of the first valve 73 is in the first state, the liquid L in the liquid transfer pipe 17 (supply pipe 16) flows through the first branch flow path 71 but does not flow through the second branch flow path 72. When the open / close state of the first valve 73 is switched to the second state, the liquid L in the liquid transfer pipe 17 (supply pipe 16) flows through the second branch flow path 72 but does not flow through the first branch flow path 71.

[0078] According to this filter device 20, when maintenance of the second filter 76 is performed, the open / close state of the first valve 73 is set to the first state, and the first filter 75 is used. When maintenance of the first filter 75 is performed, the open / close state of the first valve 73 is set to the second state, and the second filter 76 is used. In other words, even when maintenance of the first filter 75 or the second filter 76 is required, there is no need to stop the liquid supply.

[0079] Each of first filter 75 and second filter 76 shown in FIG. 5 includes magnet filter 202 and two filters 201 having micro-flow passages therein, but the configuration can be changed.

[0080] [Regarding each form of the liquid delivery system 12] 1 to 4, 6, and 7 supply the liquid L to the application head 11 that discharges the liquid L onto the workpiece W. The liquid delivery system 12 of each of the above-described embodiments has an upstream tank 14 that stores the liquid L, and a flow path portion 15 that includes a pipe connected to the upstream tank 14. The flow path section 15 (in the case of Figures 4, 6 and 7, as the primary unit U1) has a supply pipe 16 that supplies liquid L to the upstream tank 14, a liquid delivery pipe 17 that delivers the liquid L from the upstream tank 14 to the downstream side, which is the side of the application head 11, a (primary side) pump 18 that delivers the liquid L from the upstream tank 14 to the downstream side, an upstream valve 21, and a filter device 20 for removing foreign matter from the liquid.

[0081] The upstream valve 21 is located downstream of the pump 18 and selectively switches between an operating state in which the liquid L flows downstream and an upstream return state in which the liquid L is returned to the upstream tank 14. When the upstream valve 21 is in the working state, the liquid L is sent downstream. The liquid L is used to enable coating work by the coating head 11. When the upstream valve 21 is in the return state, the liquid L is returned to the upstream tank 14, and the liquid L in the upstream tank 14 can circulate.

[0082] The temperature of the liquid L affects the coating thickness of the liquid L ejected by the coating head 11. For example, the temperature of the liquid L causes thermal deformation of the coating head 11, and this thermal deformation affects the coating thickness of the liquid L. Therefore, the liquid delivery system 12 has a temperature sensor 23 that measures the temperature of the liquid L. If the temperature of the liquid L is outside the desired range, the upstream valve 21 is switched to the upstream return state. In this case, the liquid L is returned to the upstream tank 14 rather than to the downstream coating head 11. Therefore, the liquid L is not used in the coating operation by the coating head 11, and coating abnormalities due to temperature errors of the liquid L are suppressed. In other words, by managing the temperature of the liquid L, thermal deformation of the coating head 11 is suppressed, and the accuracy of the coating thickness of the liquid L can be improved.

[0083] In the embodiment shown in FIG. 3, the filter device 20 is provided in the supply pipe 16. 1, 2, 4, 6, and 7, the filter device 20 is provided in the liquid delivery pipe 17. Note that, in each of the embodiments shown in FIGS. 1, 2, 4, 6, and 7, the filter device 20 may also be provided in the supply pipe 16. That is, the filter device 20 is provided in one or both of the supply pipe 16 and the liquid transfer pipe 17 . At least one of the liquid L supplied from the liquid supply unit 13 to the upstream tank 14 and the liquid L sent from the upstream tank 14 to the coating head 11 side passes through the filter device 20, and foreign matter contained in the liquid is removed. As a result, coating abnormalities due to foreign matter are suppressed.

[0084] The liquid delivery system 12 shown in FIGS. 4, 6 and 7 has a primary unit U1 including an upstream tank 14, a primary pump 18, an upstream valve 21, a filter device 20, and the like. The liquid delivery system 12 shown in Figures 4, 6, and 7 includes a secondary unit U2 located downstream of the primary unit U1, which includes an intermediate tank 51 that stores the liquid L delivered from the upstream valve 21 in the operating state, a secondary pump 52 that delivers the liquid L from the intermediate tank 51 to the application head 11, and a downstream valve 54. The downstream valve 54 is located downstream of the intermediate tank 51 and selectively switches between a coating state in which the liquid L flows toward the coating head 11 and an intermediate return state in which the liquid L returns to the intermediate tank 51.

[0085] Even if part of the primary unit U1 (liquid temperature adjustment device 22, filter device 20) stops operating, for example, for maintenance, the liquid L is stored in the intermediate tank 51, so that the liquid L can be used to perform the coating operation by the coating head 11. When the downstream valve 54 is in the coating state, the liquid L is supplied to the coating head 11, and the liquid L is coated onto the workpiece W. When the downstream valve 54 is in the intermediate return state, the coating operation is stopped. This allows the coating device 10 to perform the coating operation intermittently.

[0086] 1, 2, 4, 6, and 7, the filter device 20 is provided midway along the liquid supply pipe 17. The liquid L delivered from the (primary) pump 18 passes through the filter device 20. That is, the liquid L delivered from the upstream tank 14 to the application head 11 passes through the filter device 20, and foreign matter contained in the liquid is removed. With this configuration, even if foreign matter is generated due to peeling of the surface of a component constituting the (primary) pump 18 or the like and gets mixed into the liquid L, the filter device 20, being located downstream of the (primary) pump 18, can remove the foreign matter.

[0087] Furthermore, the filter device 20 is provided between the (primary) pump 18 and the upstream valve 21. Therefore, even when the upstream valve 21 is in the upstream return state and the liquid L is returned to the upstream tank 14, the liquid L passes through the filter device 20 during circulation, and foreign matter contained in the liquid is removed.

[0088] 3, the filter device 20 is provided midway along the supply pipe 16. The liquid L supplied to the upstream tank 14 passes through the filter device 20. The liquid L, from which foreign matter has been removed by passing through the filter device 20, is supplied to the upstream tank 14.

[0089] 1, 4, 6, and 7 includes a liquid temperature adjusting device 22 for adjusting the temperature of the liquid L stored in the upstream tank 14 and the temperature of the liquid L in the liquid sending pipe 17. The liquid temperature adjusting device 22 includes a circulation flow path 221 through which the heat medium F flows, and a cooler 222 provided midway along the circulation flow path 221 for cooling the heat medium F. The upstream tank 14 has a tank body 141 that stores liquid, and a jacket 142. The jacket 142 is provided on the outside of the tank body 141 and constitutes a first temperature control flow path 24 through which the heat medium F passes between the jacket 142 and the tank body 141. The liquid temperature adjustment device 22 has temperature control piping 224 for supplying the heat medium F to the first temperature control flow path 24.

[0090] Heat exchange occurs between the heat medium F passing through the first temperature adjustment flow path 24 and the liquid L in the tank body 141. The temperature of the liquid L in the tank body 141 is adjusted. The liquid L in the tank body 141 is adjusted to the same temperature as the environmental temperature (room temperature) in which the coating device 10 performs the coating operation. For example, when the temperature of the liquid L in the tank body 141 is higher than room temperature, the liquid L is cooled by the heat medium F.

[0091] 1, 4, 6, and 7 is located downstream of a (primary side) pump 18 and has a temperature adjustment unit 19 through which the liquid L passes. The temperature adjustment unit 19 has an inner member 191 having an internal flow path through which the liquid L passes, and an outer member 192 provided on the outside of the inner member 191. The outer member 192 constitutes a second temperature adjustment flow path 25 between the inner member 191 and the outer member 192, through which the heat medium F passes. The liquid temperature adjustment device 22 has a temperature adjustment pipe 223 for supplying the heat medium F to the second temperature adjustment flow path 25.

[0092] Heat exchange occurs between the heat medium F passing through the second temperature adjustment flow path 25 and the liquid L passing inside the inner member 191. Even if the temperature of the liquid L increases as the liquid L passes through the (primary) pump 18, the liquid L is cooled in the temperature adjustment unit 19.

[0093] The circulation flow path 221 of the liquid temperature adjustment device 22 has a flow path configuration in which the heat medium F cooled by the cooler 222 passes through the second temperature control flow path 25, and the heat medium F that has passed through the second temperature control flow path 25 passes through the first temperature control flow path 24.

[0094] The liquid L in the upstream tank 14 is pumped out by the (primary) pump 18 and passes through the temperature adjustment unit 19. The heat medium F cooled by the cooler 222 is supplied to the second temperature adjustment flow path 25 on the temperature adjustment unit 19 side before being supplied to the first temperature adjustment flow path 24 on the upstream tank 14 side, which makes it easier to adjust the temperature of the liquid L sent to the application head 11 side to a desired temperature, and the temperature adjustment efficiency (cooling efficiency) is high. Conversely, if the heat medium F cooled by the cooler 222 is first supplied to the first temperature control flow path 24, the heat medium F that has been heat exchanged in the upstream tank 14 will pass through the second temperature control flow path 25, which may make it difficult to adjust the temperature of the liquid L supplied to the application head 11.

[0095] 1, 4, 6, and 7, the first temperature control flow path 24 and the second temperature control flow path 25 through which the heat medium F passes are connected in series in the circulation flow path 221. However, the first temperature control flow path 24 and the second temperature control flow path 25 may also be connected in parallel in the circulation flow path 221, although this is not shown.

[0096] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The technical scope of the present invention is not limited to the above-described embodiments, and includes all modifications within the scope of equivalents to the configurations described in the claims. [Explanation of symbols]

[0097] 10: Coating device 11: Coating head 12: Liquid delivery system 13: Liquid supply unit 14: Upstream tank 15: Flow path 16: Supply pipe 17: Liquid transfer pipe 18: Pump (primary pump) 19: Temperature control unit 20: Filter device 21: Upstream valve 22: Liquid temperature regulator 22: Cooler 23: Sensor (temperature sensor) 24: First temperature control flow path 25: Second temperature control flow path 51: Intermediate tank 54: downstream valve 70: branching portion 71: first branch flow path 72: Second branch flow path 73: First valve 74: Confluence 75: First filter 76: Second filter 141: Tank body 142: Jacket 191: Inner member 192: Outer member 221: Circulation flow path 222: Cooler 223: Temperature control piping 224: Temperature control piping F: Heat medium L: Liquid W: Work U1: Primary unit U2: Secondary unit

Claims

1. A liquid delivery system that supplies liquid to a coating head that discharges liquid onto a workpiece, an upstream tank for storing liquid; a flow path portion including a pipe connected to the upstream tank; and The flow path portion is a liquid supply pipe that supplies the liquid from the upstream tank to a downstream side that is the coating head side; a pump that sends the liquid in the upstream tank to the downstream side; an upstream valve located downstream of the pump for selectively switching between an operating state in which liquid flows downstream and an upstream return state in which liquid is returned to the upstream tank; a filter device provided in the liquid delivery pipe for removing foreign matter from the liquid; A liquid delivery system comprising:

2. the filter device is provided in the liquid supply pipe downstream of the pump, The liquid pumped out from the pump passes through the filter device. The liquid delivery system according to claim 1 .

3. The filter device is provided between the pump and the upstream valve. The liquid delivery system according to claim 2 .

4. the liquid supply pipe has a working pipe connected to the downstream side of the upstream valve, The filter device is provided in the working pipe. The liquid delivery system according to claim 1 .

5. A liquid delivery system that supplies liquid to a coating head that discharges liquid onto a workpiece, an upstream tank for storing liquid; a flow path portion including a pipe connected to the upstream tank; and The flow path portion is a supply pipe for supplying liquid to the upstream tank; a liquid supply pipe that supplies the liquid from the upstream tank to a downstream side that is the coating head side; a pump that sends the liquid in the upstream tank to the downstream side; an upstream valve located downstream of the pump for selectively switching between an operating state in which liquid flows downstream and an upstream return state in which liquid is returned to the upstream tank; a filter device provided in the supply pipe for removing foreign matter from the liquid; A liquid delivery system comprising:

6. The filter device comprises: a branch portion through which the liquid passes; a first branch flow path and a second branch flow path that branch off from the branching portion and are parallel to each other; a valve for selectively allowing the liquid to flow into one of the first branch flow path and the second branch flow path; a junction portion where the first branch flow path and the second branch flow path join together; a first filter provided in the first branch flow path; a second filter provided in the second branch flow path; The liquid delivery system according to any one of claims 1 to 5, comprising:

7. a sensor for measuring the temperature of the liquid; If the temperature of the liquid is out of range, switching the upstream valve to the upstream return state. The liquid delivery system according to any one of claims 1 to 5.

8. a liquid temperature adjusting device for adjusting the temperature of one or both of the liquid stored in the upstream tank and the liquid in the liquid sending pipe; The liquid delivery system according to any one of claims 1 to 5.

9. The upstream tank is A tank body that stores liquid; a jacket provided on the outside of the tank body and constituting a first temperature control flow path through which a heat medium passes between the jacket and the tank body; and the liquid temperature adjustment device has a temperature adjustment pipe for supplying a heat medium to the first temperature adjustment flow path; The liquid delivery system according to claim 8 .

10. the liquid delivery pipe has a temperature control section located downstream of the pump and through which the liquid passes; The temperature control unit is an inner member having a flow path therein through which the liquid passes; an outer member that is provided outside the inner member and that constitutes a second temperature control flow path through which a heat medium passes between the outer member and the inner member; and the liquid temperature adjustment device has a temperature adjustment pipe for supplying a heat medium to the second temperature adjustment flow path. The liquid delivery system according to claim 9 .

11. the liquid temperature adjustment device includes a circulation flow path through which the heat medium flows, and a cooler that is provided midway along the circulation flow path and cools the heat medium, the circulation flow path has a flow path configuration in which the heat medium cooled by the cooler passes through the second temperature control flow path, and the heat medium that has passed through the second temperature control flow path passes through the first temperature control flow path. The liquid delivery system according to claim 10.

12. a primary unit including the upstream tank, the pump, the upstream valve, and the filter device; As a secondary unit, an intermediate tank that stores the liquid sent from the upstream valve in the working state; a downstream valve located downstream of the intermediate tank for selectively switching between a coating state in which the liquid flows toward the coating head and an intermediate return state in which the liquid returns to the intermediate tank; The liquid delivery system according to any one of claims 1 to 5.

13. a primary unit including the upstream tank, the pump, the upstream valve, and the filter device; As a secondary unit, an intermediate tank that stores the liquid sent from the upstream valve in the working state; a downstream valve located downstream of the intermediate tank for selectively switching between a coating state in which the liquid flows toward the coating head and an intermediate return state in which the liquid returns to the intermediate tank; The liquid delivery system according to claim 6 .

14. a primary unit including the upstream tank, the pump, the upstream valve, and the filter device; As a secondary unit, an intermediate tank that stores the liquid sent from the upstream valve in the working state; a downstream valve located downstream of the intermediate tank for selectively switching between a coating state in which the liquid flows toward the coating head and an intermediate return state in which the liquid returns to the intermediate tank; The liquid delivery system according to claim 8 .

15. a primary unit including the upstream tank, the pump, the upstream valve, and the filter device; As a secondary unit, an intermediate tank that stores the liquid sent from the upstream valve in the working state; a downstream valve located downstream of the intermediate tank for selectively switching between a coating state in which the liquid flows toward the coating head and an intermediate return state in which the liquid returns to the intermediate tank; The liquid delivery system according to claim 9 .

16. a primary unit including the upstream tank, the pump, the upstream valve, and the filter device; As a secondary unit, an intermediate tank that stores the liquid sent from the upstream valve in the working state; a downstream valve located downstream of the intermediate tank for selectively switching between a coating state in which the liquid flows toward the coating head and an intermediate return state in which the liquid returns to the intermediate tank; The liquid delivery system according to claim 10.

17. a primary unit including the upstream tank, the pump, the upstream valve, and the filter device; As a secondary unit, an intermediate tank that stores the liquid sent from the upstream valve in the working state; a downstream valve located downstream of the intermediate tank for selectively switching between a coating state in which the liquid flows toward the coating head and an intermediate return state in which the liquid returns to the intermediate tank; The liquid delivery system according to claim 11.

18. having a plurality of the primary units; The liquid delivery system according to claim 12.

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