JP7008338B2 - Coating device and bubble removal method - Google Patents

Description

The present invention relates to a coating device and a method for removing air bubbles.

Conventionally, a coating device is used when applying a coating liquid onto an object. In the coating head of the coating apparatus, the pressure chamber is filled with the coating liquid, and by applying pressure to the coating liquid, the coating liquid is discharged from the discharge port continuous with the pressure chamber. In this case, if air bubbles are mixed in the pressure chamber, the pressure applied to the pressure chamber is absorbed by the air bubbles. As a result, the coating liquid is not properly discharged from the discharge port, and coating defects such as the amount of the coating liquid applied to each position being smaller than the set amount occur. Further, if air bubbles are present in the discharge port, external air may be sucked into the pressure chamber through the discharge port, and the amount of air bubbles in the pressure chamber may increase. In this case, it becomes difficult to discharge the coating liquid. Therefore, in the coating device, air bubbles in the pressure chamber are removed.

For example, in Japanese Patent Application Laid-Open No. 2009-131788, a discharge coating liquid smaller than the amount of the coating liquid supplied from the coating liquid supply pump to the slit nozzle is discharged from the slit nozzle by the coating liquid discharge suction pump. As a result, the air bubbles mixed in the pooled portion of the slit nozzle are discharged together with the discharged coating liquid. In this method, the coating liquid is also discharged from the discharge port of the slit nozzle.

Further, Japanese Patent Application Laid-Open No. 2007-21904 discloses an inkjet recording device in which a cap member is brought into close contact with a nozzle surface to cap a nozzle when non-printing is performed. In the inkjet recording device, bubbles in the recording head and thickened ink are removed by depressurizing the inside of the cap member and sucking ink from the nozzle.
Japanese Unexamined Patent Publication No. 2009-131788 Japanese Unexamined Patent Publication No. 2007-21904

By the way, in the method of JP-A-2009-131788, the pressure in the internal space of the coating head is momentarily lowered due to the pulsation of the pump or the like, and there is a possibility that air invades from the discharge port into the internal space. Further, it is conceivable to discharge bubbles together with the coating liquid from the discharge port as in the method of JP-A-2007-21904, but since the diameter of the discharge port is usually small, the bubbles are efficiently discharged through the discharge port. It is difficult to discharge. Therefore, in the coating head, there is a demand for a method of efficiently removing air bubbles in the internal space while suppressing the intrusion of air from the discharge port into the internal space.

The present invention has been made in view of the above problems, and an object of the present invention is to efficiently remove air bubbles in the internal space while suppressing the intrusion of air from the discharge port into the internal space.

An exemplary coating device of the present invention is a coating that supplies the coating liquid to an internal space filled with the coating liquid, a coating head having a discharge port continuous with the internal space, and the internal space of the coating head. A coating liquid discharge unit having a liquid supply unit and a discharge flow path connected to the internal space and discharging the coating liquid in the internal space through the discharge flow path, and the coating liquid dripping from the discharge port. It is provided with a liquid dripping detection unit for detecting the above and a control unit. The control unit controls at least one of the coating liquid supply unit and the coating liquid discharge unit based on the output of the liquid dripping detection unit to form a liquid dripping state in which the coating liquid drips from the discharge port. do.

The exemplary method for removing air bubbles of the present invention is performed in a coating device. The coating device includes an internal space filled with the coating liquid, a coating head having a discharge port continuous with the internal space, and a coating liquid supply unit for supplying the coating liquid to the internal space of the coating head. A coating liquid discharging portion having a discharge flow path connected to the internal space and discharging the coating liquid in the internal space through the discharge flow path, and a liquid dripping for detecting the coating liquid dripping from the discharge port. It is equipped with a detection unit. The bubble removing method a) controls at least one of the coating liquid supply unit and the coating liquid discharging unit based on the output of the liquid dripping detection unit, so that the coating liquid drips from the discharge port. In parallel with the step of forming the state and b) the step a), the coating liquid supply unit supplies the coating liquid to the internal space, and the coating liquid discharging unit applies the coating liquid from the internal space. It is provided with a process of discharging the liquid.

According to the present invention, it is possible to efficiently remove air bubbles in the internal space while suppressing the intrusion of air from the discharge port into the internal space.

FIG. 1 is a diagram showing a configuration of a coating device. FIG. 2A is a diagram showing the vicinity of the liquid dripping detection unit. FIG. 2B is a diagram showing the vicinity of the liquid dripping detection unit. FIG. 2C is a diagram showing the vicinity of the liquid dripping detection unit. FIG. 3 is a diagram showing the flow of the bubble removing process. FIG. 4 is a diagram showing another example of the coating device.

FIG. 1 is a diagram showing a configuration of a coating device 1 according to an exemplary embodiment of the present invention. The coating device 1 is a device that coats a predetermined coating liquid on an object 9 which is various substrates such as a printed circuit board and a semiconductor substrate. The object 9 may be a mechanical part or the like. The coating liquid is, for example, various adhesives (epoxy, UV curing, etc.), encapsulants, underfill agents, greases, and the like.

The coating device 1 includes a control unit 10, a moving mechanism 2, a coating head 3, a coating liquid supply unit 4, a coating liquid discharge unit 5, and a liquid dripping detection unit 6. The control unit 10 is responsible for overall control of the coating device 1. The moving mechanism 2 includes a stage 21 and a stage moving mechanism 22. The stage 21 holds the object 9. The stage moving mechanism 22 moves the stage 21 with respect to the coating head 3. The moving directions of the stage 21 by the stage moving mechanism 22 are, for example, two directions perpendicular to each other. Typically, these moving directions are perpendicular to the discharge direction of the coating liquid by the coating head 3. The stage moving mechanism 22 may rotate the stage 21 about an axis parallel to the discharge direction. A recovery unit 23 for collecting the coating liquid from the coating head 3 is provided on the stage 21.

The coating head 3 includes a main body portion 31, a wetted film 34, and a pressurizing portion 35. FIG. 1 shows a cross section of the coating head 3 on a surface including the center line of the discharge port 321 described later. The main body 31 is formed of, for example, metal or the like. The main body 31 forms the bottom surface and the side surface of the pressure chamber 32 filled with the coating liquid. The pressure chamber 32 is an internal space of the coating head 3, for example, a columnar shape. A supply port 322 and a discharge port 323 are provided on the side surface of the pressure chamber 32. The supply port 322 and the discharge port 323 are arranged at positions facing each other. The supply port 322 and the discharge port 323 are continuous with the pressure chamber 32. A discharge port 321 is provided on the bottom surface of the pressure chamber 32. The discharge port 321 is a through hole extending straight from the pressure chamber 32. The diameter of the discharge port 321 is, for example, 0.3 mm. The discharge port 321 opens outward on the surface 311 of the main body 31 facing the stage 21. Hereinafter, the surface 311 is referred to as "opposing surface 311". The facing surface 311 is parallel to the stage 21. As will be described later, the facing surface 311 may be inclined with respect to the stage 21.

The wetted film 34 is a diaphragm formed of a metal or the like. In the pressure chamber 32, the wetted film 34 faces the discharge port 321. The wetted film 34 forms a surface facing the bottom surface of the pressure chamber 32. The surface of the wetted film 34 on the pressure chamber 32 side is a wetted surface in contact with the coating liquid in the pressure chamber 32. The outer edge portion of the wetted film 34 is fixed to the main body portion 31. Except for the discharge port 321 and the supply port 322 and the discharge port 323, the pressure chamber 32 is sealed by the main body 31 and the wetted film 34.

The pressurizing unit 35 includes a piezoelectric element 351. The piezoelectric element 351 is fixed to a surface different from the wetted surface of the wetted film 34. By supplying a drive voltage to the piezoelectric element 351 by a drive circuit (not shown), the piezoelectric element 351 expands and contracts, and the amount of deflection of the wetted film 34 changes. When the wetted film 34 bends toward the discharge port 321, pressure is applied to the coating liquid in the pressure chamber 32, and the coating liquid is discharged from the discharge port 321 to the outside. In this way, the pressurizing unit 35 bends the wetted film 34 toward the inside of the pressure chamber 32, so that the coating liquid is discharged from the discharge port 321.

The coating liquid supply unit 4 supplies the coating liquid to the pressure chamber 32 of the coating head 3. The coating liquid supply unit 4 includes a coating liquid tank 41, a supply flow path 42, and a pressure adjusting unit 43. The coating liquid tank 41 stores the coating liquid. The inside of the coating liquid tank 41 is hermetically sealed. One end of the supply flow path 42 is connected to the coating liquid tank 41. The other end is connected to the pressure chamber 32 via the supply port 322. That is, the inside of the coating liquid tank 41 and the pressure chamber 32 of the coating head 3 are spatially continuous via the supply flow path 42. The coating liquid tank 41 is arranged vertically above the pressure chamber 32. The pressure adjusting unit 43 adjusts the pressure in the coating liquid tank 41. The pressure adjusting unit 43 includes, for example, a pressure adjusting pump. The pressure adjusting unit 43 adjusts the pressure in the coating liquid tank 41 to an arbitrary value within the pressure range including the atmospheric pressure. The lower limit of the pressure range is lower than the atmospheric pressure, and the upper limit of the pressure range is higher than the atmospheric pressure.

The coating liquid discharging unit 5 includes a discharging flow path 51, an opening / closing unit 52, a bubble detection unit 53, a liquid feeding pump 54, and a liquid draining tank 55. One end of the discharge flow path 51 is connected to the pressure chamber 32 via the discharge port 323. The other end is connected to the drainage tank 55. The diameter of the discharge flow path 51 is larger than the diameter of the discharge port 321. That is, the cross-sectional area perpendicular to the direction in which the coating liquid flows in the discharge flow path 51 is larger than the cross-sectional area of the discharge port 321.

In the discharge flow path 51, an opening / closing unit 52, a bubble detection unit 53, and a liquid feed pump 54 are provided in this order from the coating head 3 toward the liquid discharge tank 55. The opening / closing unit 52 is, for example, an on / off valve, and opens / closes the discharge flow path 51. The opening / closing portion 52 is arranged at a position close to the coating head 3. It is preferable that the opening / closing portion 52 is provided closest to the coating head 3 among the configurations provided in the discharge flow path 51. The liquid feed pump 54 causes the coating liquid in the discharge flow path 51 to flow from the coating head 3 side to the drainage tank 55 side. The liquid feed pump 54 has a variable output, that is, a liquid feed capacity, by changing the value of a drive parameter such as a supplied current or voltage. By driving the liquid feed pump 54 with the opening / closing portion 52 open, the coating liquid in the pressure chamber 32 is discharged to the drainage tank 55 via the discharge flow path 51. The bubble detection unit 53 acquires the presence or absence of bubbles contained in the coating liquid flowing through the discharge flow path 51. That is, the bubble detection unit 53 detects bubbles. The bubble detection unit 53 is, for example, an ultrasonic type or an optical type sensor.

2A to 2C are views showing the vicinity of the liquid dripping detection unit 6. 2A to 2C show a cross section of the main body 31 on the surface including the center line of the discharge port 321. The liquid dripping detection unit 6 includes an emission unit 61 and a light receiving unit 62. The emitting unit 61 and the light receiving unit 62 are attached to the facing surface 311 of the coating head 3. As described above, the facing surface 311 is a surface on which the discharge port 321 opens in the coating head 3. The emitting unit 61 and the light receiving unit 62 are arranged at two positions on the facing surface 311 with the discharge port 321 sandwiched between them. The emitting unit 61 emits the detection light along the facing surface 311. The detected light is directed to the light receiving unit 62. In FIGS. 2A to 2C, the path K1 of the detection light from the emitting unit 61 to the light receiving unit 62 is shown by a alternate long and short dash line.

As shown in FIG. 2A, the detection light is received by the light receiving unit 62 in a state where the liquid level of the coating liquid is formed in the discharge port 321. As shown in FIG. 2B, when the coating liquid drips from the discharge port 321 and intersects with the detection light path K1, the detection light is blocked by the coating liquid and is not received by the light receiving unit 62. In this way, the liquid dripping detection unit 6 detects the coating liquid dripping from the discharge port 321. When the coating liquid is detected, the detection signal is output to the control unit 10. In the following description, the state in which the coating liquid intersects with the detection light path K1 and the detection light is not received by the light receiving unit 62 is described.
It is assumed that the coating liquid is dripping from the discharge port 321 or that the liquid dripping is occurring. The detection light path K1 is slightly separated from the facing surface 311 by, for example, about 1 mm. Therefore, as shown in FIG. 2C, the coating liquid slightly rising from the discharge port 321 does not intersect with the detection light path K1 and is not treated as the occurrence of liquid dripping.

In the normal operation of the coating device 1, the control unit 10 controls the moving mechanism 2 and the coating head 3 to coat the coating liquid on the object 9. Specifically, as the moving mechanism 2 moves the stage 21, the position of the coating target on the object 9 is arranged at a position facing the discharge port 321. Then, by supplying the driving voltage to the piezoelectric element 351, the droplets of the coating liquid are discharged from the discharge port 321 toward the above position. Since the piezoelectric element 351 has high responsiveness, it is possible to easily reduce and adjust the amount of droplets by controlling the drive voltage. In the coating device 1, the coating liquid is applied to all the positions of the coating target on the object 9 by repeatedly moving the object 9 and discharging the coating liquid. Depending on the design of the coating head 3, the coating liquid may be discharged by a drive source other than the piezoelectric element 351.

In the above normal operation, the pressure in the coating liquid tank 41 is adjusted to a predetermined normal pressure value by the pressure adjusting unit 43. The normal pressure value is lower than atmospheric pressure, that is, negative pressure. Therefore, when the coating liquid is not discharged from the discharge port 321, a meniscus of the coating liquid is formed inside the discharge port 321, that is, on the pressure chamber 32 side of the facing surface 311 as shown in FIG. 2A. This prevents the coating liquid from falling from the discharge port 321 without being driven by the piezoelectric element 351. Further, in the normal operation, the opening / closing portion 52 keeps the discharge flow path 51 closed. As a result, the coating liquid in the pressure chamber 32 is prevented from flowing to the discharge flow path 51, and the coating liquid is appropriately discharged from the discharge port 321 by driving the pressurizing unit 35.

In the coating device 1, a bubble removing process for removing bubbles in the pressure chamber 32 is performed at predetermined intervals. The bubble removing process may be performed by an operator at any time. FIG. 3 is a diagram showing the flow of the bubble removing process. In the bubble removing process, first, as shown by the alternate long and short dash line in FIG. 1, the recovery unit 23 on the stage 21 is arranged by the moving mechanism 2 at a position facing the discharge port 321 of the coating head 3. Step S11). In the bubble removing process, the coating liquid is not discharged from the discharge port 321 in principle, but even if a droplet of the coating liquid falls from the discharge port 321, the droplet is received by the collection unit 23.

Subsequently, the pressure adjusting unit 43 adjusts the pressure in the coating liquid tank 41 to a predetermined set pressure value higher than the normal pressure value (step S12). The set pressure value is a positive pressure higher than the atmospheric pressure. In the bubble removing treatment in this treatment example, the pressure in the coating liquid tank 41 is always maintained at a set pressure value. In the coating head 3, the coating liquid is collected in the discharge port 321 on the facing surface 311 due to the positive pressure in the coating liquid tank 41. The viscosity of the coating liquid used in the coating apparatus 1 is relatively high, for example, 100 millipascal seconds (mPa · s) or more and 300,000 mPa · s or less. The coating liquid in the vicinity of the discharge port 321 gradually extends downward from the discharge port 321 while being held by the surface tension. The coating liquid extends from, for example, the discharge port 321 by several mm. The set pressure value may be equal to the atmospheric pressure as long as the coating liquid can be stored in the discharge port 321 on the facing surface 311.

The liquid dripping detection unit 6 acquires the presence or absence of liquid dripping (step S13). As shown in FIG. 2B, when the coating liquid intersects the detection light path K1, the liquid dripping detection unit 6 detects the liquid dripping, and the detection signal is output to the control unit 10 (step S14). At this time, as a general rule, a liquid dripping state is formed in which the coating liquid drips from the discharge port 321. In the liquid dripping state, the coating liquid dripping from the discharge port 321 does not fall, and the coating liquid is not continuous between the discharge port 321 and the collection unit 23. In the liquid dripping state, the coating liquid is held by surface tension in a state of hanging from the discharge port 321 and the entire discharge port 321 is covered with the coating liquid. In other words, the discharge port 321 is sealed by the coating liquid. Actually, the acquisition of the presence or absence of dripping by the dripping detection unit 6 is repeated every minute time (steps S13 and S14), but at present, the process of step S18 in FIG. 3 is not performed.

When the dripping is detected, the driving of the liquid feeding pump 54 of FIG. 1 is started. As a result, the coating liquid in the pressure chamber 32 is sucked into the discharge flow path 51 and discharged to the drainage tank 55 (step S15). In the coating liquid discharging unit 5, the liquid feeding pump 54 is driven with the value of the driving parameter described above being constant at a predetermined set input value. Further, as the coating liquid is discharged from the pressure chamber 32, the coating liquid in the coating liquid tank 41 flows into the pressure chamber 32 via the supply flow path 42. In this way, in parallel with the formation of the liquid drooping state, the coating liquid supply unit 4 supplies the coating liquid to the pressure chamber 32, and the coating liquid discharging unit 5 discharges the coating liquid from the pressure chamber 32. .. As a result, the bubbles in the pressure chamber 32 are discharged together with the coating liquid through the discharge flow path 51. At this time, since the entire discharge port 321 is covered with the coating liquid in the drooping state, it is possible to prevent the surrounding air from entering the pressure chamber 32 through the discharge port 321. The coating liquid discharged to the drainage tank 55 may be reused as appropriate, whereby the running cost in the coating device 1 can be reduced.

The bubble detection unit 53 acquires the presence or absence of bubbles in the coating liquid flowing through the discharge flow path 51 (step S16). In the control unit 10, when the bubble is detected by the bubble detection unit 53 during a predetermined time (step S17), it is determined that the bubble remains in the pressure chamber 32. Then, returning to step S13, the presence or absence of dripping is acquired by the dripping detection unit 6.

Here, a negative pressure is applied to the coating liquid in the pressure chamber 32 by the discharge operation of the coating liquid by the coating liquid discharge unit 5. Therefore, the length of the coating liquid dripping from the discharge port 321 is reduced by driving the liquid feed pump 54. Actually, the set input value of the liquid feeding pump 54 that gradually reduces the length of the coating liquid in the drooping state with respect to the set pressure value in the coating liquid tank 41 is acquired in advance by an experiment or the like.

When the dripping is detected by the dripping detecting unit 6 (step S14), the pressure adjustment at the set pressure value in the coating liquid tank 41 and the driving at the set input value of the liquid feeding pump 54 are maintained. (Step S15). In this way, it is determined that air bubbles remain in the pressure chamber 32 (steps S16 and S17), and while the coating liquid is dripping from the discharge port 321 (steps S13 and S14), the pressure chamber 32 is reached. The supply of the coating liquid and the discharge of the coating liquid from the pressure chamber 32 are continued (step S15). Actually, the operation related to the detection of bubbles (steps S16 and S17) and the operation related to the detection of dripping (steps S13 and S14) are performed in parallel with each other. In the bubble removing process, the pressurizing unit 35 is not driven.

When the dripping detection unit 6 no longer detects dripping (see FIGS. 2C) (steps S13 and S14), the value of the drive parameter in the liquid feed pump 54 is reduced from the set input value (step S18). In the present embodiment, the value of the drive parameter is set to 0, and the liquid feed pump 54 is stopped. At this time, the pressure in the coating liquid tank 41 is maintained at the set pressure value, and the length of the coating liquid extending vertically downward from the discharge port 321 becomes large. As a result, the drooping state of the coating liquid is formed again. As described above, in steps S13, S14, and S18, the control unit 10 controls the coating liquid discharging unit 5 based on the output of the liquid dripping detecting unit 6, so that the liquid dripping state of the coating liquid is formed.

When the liquid dripping is detected by the liquid dripping detection unit 6 (steps S13 and S14), the value of the drive parameter in the liquid feed pump 54 is returned to the set input value (step S15). As a result, the discharge of the coating liquid from the pressure chamber 32 and the accompanying supply of the coating liquid into the pressure chamber 32 are restarted. As described above, in the coating device 1, the bubbles in the pressure chamber 32 are discharged together with the coating liquid through the discharge flow path 51 during the period when the liquid dripping state is formed.

When bubbles are not detected by the bubble detection unit 53 for a predetermined time during the period in which the coating liquid in the pressure chamber 32 is discharged through the discharge flow path 51 (steps S16 and S17), the pressure chamber is controlled by the control unit 10. It is determined that no bubbles remain in 32. Then, when the liquid feed pump 54 is stopped, the discharge of the coating liquid in the pressure chamber 32 is completed. Further, the pressure in the coating liquid tank 41 is adjusted to a normal pressure value which is a negative pressure (step S19), and as shown in FIG. 2A, the liquid level of the coating liquid is formed inside the discharge port 321. In this way, the bubble removal process is completed. The preferred coating device 1 is provided with a wipe mechanism (not shown). In this case, after adjusting the pressure in the coating liquid tank 41 to a normal pressure value, unnecessary coating liquid or the like adhering to the facing surface 311 of the coating head 3 is wiped off.

As described above, in the bubble removing process of the coating device 1, the control unit 10 controls the coating liquid discharging unit 5 based on the output of the liquid dripping detecting unit 6, so that the discharge port 321 continuous with the pressure chamber 32 Therefore, a dripping state is formed in which the coating liquid drips. As a result, it is possible to suppress the intrusion of surrounding air from the discharge port 321 into the pressure chamber 32. Further, by discharging the coating liquid in the pressure chamber 32 through the discharge flow path 51, the flow rate of the coating liquid can be increased as compared with the case where the coating liquid is discharged through the discharge port 321. Bubbles in the chamber 32 can be removed more reliably and efficiently. As a result, it is possible to prevent the occurrence of coating defects in the coating of the coating liquid on the object 9, that is, to improve the reliability of the coating device 1, without adopting a complicated structure and operation. Further, the bubble detection unit 53 detects bubbles contained in the coating liquid flowing through the discharge flow path 51. As a result, the end point of removal of air bubbles in the pressure chamber 32 can be accurately detected.

In the coating device 1, the liquid dripping detection unit 6 attached to the coating head 3 is used to adhere to the periphery of the discharge port 321 and harden the coating liquid or the like, foreign matter in the vicinity of the discharge port 321 and from the discharge port 321. Unintended dripping can also be detected. For example, when the detection signal is output by the liquid dripping detection unit 6 when the piezoelectric element 351 is not driven in normal operation, the application of the coating liquid to the object 9 is interrupted. Then, after the vicinity of the discharge port 321 is wiped off, the application of the coating liquid is restarted. This makes it possible to prevent the foreign matter and the like from adhering to the object 9.

FIG. 4 is a diagram showing another example of the coating device 1. The coating device 1 of FIG. 4 differs from the coating device 1 of FIG. 1 in that the liquid dripping detecting unit 6 is provided in the collecting unit 23. Other configurations are the same as those of the coating device 1 of FIG. 1, and the same configurations are designated by the same reference numerals.

In the coating device 1 of FIG. 4, the emitting unit 61 and the light receiving unit 62 of the liquid dripping detection unit 6 are provided at the upper end portion of the collecting unit 23. In the bubble removing process, as shown by the solid line in FIG. 4, the collecting unit 23 is arranged at a position facing the discharge port 321 of the coating head 3 by the moving mechanism 2 (FIG. 3: step S11). At this time, the emitting unit 61 and the light receiving unit 62 are close to the facing surface 311 of the coating head 3 with a small gap. Further, when focusing on the direction along the facing surface 311, the emitting unit 61 and the light receiving unit 62 are arranged at two positions sandwiching the discharge port 321 in between. As a result, the liquid dripping detection unit 6 can detect the coating liquid dripping from the discharge port 321. The processing of steps S12 to S19 is the same as that of the coating device 1 of FIG.

As described above, in the coating device 1 of FIG. 4, the liquid dripping detection unit 6 is provided separately from the coating head 3. In the bubble removing process, the liquid dripping detection unit 6 is arranged at a position close to the discharge port 321 by the moving mechanism 2. Then, a liquid dripping state is formed based on the output of the liquid dripping detection unit 6. As a result, air bubbles in the pressure chamber 32 can be removed while suppressing the intrusion of air from the discharge port 321 into the pressure chamber 32. In the coating device 1 of FIG. 4, the structure of the coating head 3 can be simplified, and the coating head 3 can be easily miniaturized. The liquid dripping detection unit 6 may move relative to the coating head 3. For example, by providing a moving mechanism for moving the coating head 3, the liquid dripping detecting unit 6 is close to the discharge port 321 in the bubble removing process. It may be placed at the desired position.

The coating device 1 can be modified in various ways.

In step S18 of FIG. 3, if the liquid drooping state is formed, the value of the drive parameter of the liquid feed pump 54 may be adjusted to a value larger than 0 and smaller than the set input value. .. Further, the drooping state may be reformed by increasing the pressure in the coating liquid tank 41 to be larger than the set pressure value while maintaining the value of the drive parameter of the liquid feed pump 54 at the set input value. Further, the value of the drive parameter of the liquid feed pump 54 may be made smaller than the set input value, and the pressure in the coating liquid tank 41 may be made larger than the set pressure value. In this way, the control unit 10 controls at least one of the coating liquid supply unit 4 and the coating liquid discharging unit 5 based on the output of the liquid dripping detecting unit 6, so that the coating liquid drips from the discharge port 321. A state is formed.

In the coating device 1, the normal of the facing surface 311 is parallel to the vertical direction, but if the entire discharge port 321 is covered with the coating liquid in the drooping state, the normal is relative to the vertical direction. May be tilted. For example, the angle formed by the normal of the facing surface 311 with respect to the vertical direction is 45 degrees or less, preferably 30 degrees or less. The angle is, of course, 0 degrees or more.

In addition to light, the liquid dripping detection unit 6 may detect the coating liquid dripping from the discharge port 321 by using, for example, ultrasonic waves. Further, the liquid dripping detection unit 6 may include an image pickup unit and an image analysis unit. In this case, the image pickup unit acquires an image in the vicinity of the discharge port 321, and the image analysis unit analyzes the image to acquire the presence or absence of the coating liquid dripping from the discharge port 321.

The configurations of the coating liquid supply unit 4 and the coating liquid discharging unit 5 may be appropriately changed. For example, the coating liquid may be supplied into the pressure chamber 32 by the liquid feeding pump in the coating liquid supply unit 4. Further, the coating liquid in the pressure chamber 32 may be discharged by manually operating the pump including the syringe in the coating liquid discharging unit 5.

The bubble detection unit 53 may be omitted in the coating liquid discharge unit 5. In this case, for example, the discharge flow path 51 is formed of a transparent tube, and the operator confirms the presence or absence of bubbles in the coating liquid flowing through the discharge flow path 51, so that the end point of removing the bubbles in the pressure chamber 32 is reached. Detected. Further, the opening / closing portion 52 may be omitted. In this case, the flow path resistance of the discharge flow path 51 should be made larger than that of the supply flow path 42 by making the cross-sectional area of the discharge flow path 51 perpendicular to the flow direction of the coating liquid smaller than that of the supply flow path 42. Is preferable. This easily prevents the coating liquid from flowing into the discharge flow path 51 during normal operation.

The above-described embodiments and configurations in the respective modifications may be appropriately combined as long as they do not conflict with each other.

The coating apparatus according to the present invention can be used for various purposes. Further, the bubble removing method can be used in various coating devices.

1 Coating device 2 Moving mechanism 3 Coating head 4 Coating liquid supply unit 5 Coating liquid discharge unit 6 Liquid dripping detection unit 10 Control unit 32 Pressure chamber 41 Coating liquid tank 42 Supply flow path 43 Pressure adjustment unit 51 Discharge flow path 52 Opening / closing unit 53 Bubble detection unit 61 Output unit 62 Light receiving unit 311 Facing surface 321 Discharge port S11 to S19 Step

Claims (11)

An internal space filled with the coating liquid, and a coating head having a discharge port continuous with the internal space.
A coating liquid supply unit that supplies the coating liquid to the internal space of the coating head,
A coating liquid discharge portion having a discharge flow path connected to the internal space and discharging the coating liquid in the internal space via the discharge flow path.
A liquid dripping detection unit that detects the coating liquid dripping from the discharge port,
With a control unit,
The control unit controls at least one of the coating liquid supply unit and the coating liquid discharging unit based on the output of the liquid dripping detection unit, so that the coating liquid is hung from the discharge port by surface tension. A coating device that is held and forms a dripping state in which the discharge port is sealed by the coating liquid . A claim that the control unit supplies the coating liquid to the internal space by the coating liquid supply unit and discharges the coating liquid from the internal space by the coating liquid discharge unit in the liquid drooping state. Item 1. The coating apparatus according to Item 1. The coating device according to claim 1 or 2, wherein the coating liquid discharging unit has a bubble detecting unit for detecting bubbles contained in the coating liquid flowing through the discharge flow path. The coating device according to any one of claims 1 to 3, wherein the dripping detection unit is attached to the coating head. One of claims 1 to 3, further comprising a moving mechanism for arranging the liquid dripping detection unit at a position close to the discharge port by moving the liquid dripping detection unit relative to the coating head. The coating device according to one. The dripping detection unit
An emitting portion that emits detection light along a surface of the coating head through which the ejection port opens,
It has a light receiving unit that receives the detected light, and has a light receiving portion.
The coating device according to any one of claims 1 to 5, wherein the detection light is blocked while the coating liquid is dripping from the discharge port. The coating liquid discharging portion further has an opening / closing portion that opens and closes the discharging flow path at a position close to the coating head.
The coating device according to any one of claims 1 to 6, wherein the opening / closing portion keeps the discharge flow path closed during a normal operation in which the coating head discharges the coating liquid from the discharge port. The coating liquid supply unit
A coating liquid tank for storing the coating liquid and
It has a supply flow path in which one end is connected to the coating liquid tank and the other end is connected to the internal space, and a pressure adjusting unit for adjusting the pressure in the coating liquid tank.
Claims 1 to 7 that when the liquid dripping state is formed, the pressure adjusting unit raises the pressure in the coating liquid tank to be higher than in the normal operation in which the coating liquid is discharged from the discharge port. The coating apparatus according to any one of the above. It is a method of removing air bubbles in a coating device.
The coating device
An internal space filled with the coating liquid, and a coating head having a discharge port continuous with the internal space.
A coating liquid supply unit that supplies the coating liquid to the internal space of the coating head,
A coating liquid discharge portion having a discharge flow path connected to the internal space and discharging the coating liquid in the internal space through the discharge flow path.
A liquid dripping detection unit for detecting the coating liquid dripping from the discharge port is provided.
The bubble removing method
a) By controlling at least one of the coating liquid supply unit and the coating liquid discharging unit based on the output of the liquid dripping detection unit, the coating liquid is held by surface tension in a state of hanging from the discharge port. The process of forming a liquid drooping state in which the discharge port is sealed with the coating liquid , and
b) In parallel with the step a), the step of supplying the coating liquid to the internal space by the coating liquid supply unit and discharging the coating liquid from the internal space by the coating liquid discharging unit. , Equipped with. A step of detecting air bubbles contained in the coating liquid flowing through the discharge flow path, and
The bubble removing method according to claim 9, further comprising the steps of ending the steps a) and b) when the bubbles are not detected for a predetermined time. The coating liquid supply unit
A coating liquid tank for storing the coating liquid and
A supply flow path in which one end is connected to the coating liquid tank and the other end is connected to the internal space.
It has a pressure adjusting unit for adjusting the pressure in the coating liquid tank, and has.
The bubble removal according to claim 9 or 10, wherein in the step a), the pressure in the coating liquid tank is increased by the pressure adjusting unit as compared with the normal operation in which the coating liquid is discharged from the discharge port. Method.

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