JP7475189B2 - Masking jig - Google Patents

Description

The present invention relates to a masking tool for an electrostatic spraying device using the electrospray method.

In a conventional electrostatic spraying device that uses the electrospray method, in which a voltage is applied between a liquid spraying part and a part of a different pole that is the opposite pole to the liquid spraying part, a liquid such as paint is separated from the liquid spraying part in a charged state by electrostatic force, atomized, and the atomized liquid is sprayed onto the workpiece, a masking jig with holes of a predetermined shape and pattern is placed in contact with the workpiece, and a thin film corresponding to the holes of the predetermined shape and pattern is formed on the workpiece (see Patent Document 1).

The masking jig described in Patent Document 1 comprises a masking body and a masking auxiliary body, the masking auxiliary body being arranged so as to define the coated portion of the workpiece and the non-coated portion of the workpiece, the masking body being arranged so as to cover the non-coated portion not covered by the masking auxiliary body, the masking auxiliary body being formed using a conductive material, and the masking body being formed using an insulating material. The masking jig is placed so as to come into contact with the workpiece.

JP 2016-221433 A

When the masking jig is placed in contact with the workpiece, the liquid cannot be applied to the workpiece while moving the liquid spray unit and masking jig, and it is not possible to paint dots, lines, or pictures, for example. In addition, there is a problem that it cannot be used for painting work when it is difficult to place the masking jig on the workpiece, such as when the workpiece has a complex shape.

The present invention was made in consideration of the above problems, and aims to provide a masking tool that can be used for special coating operations such as drawing dots, lines, or pictures, or for coating operations where it is difficult to place the masking tool on the workpiece.

In order to achieve the above object, the present invention is realized as follows.
(1) The masking tool of the present invention is a masking tool used in an electrostatic spraying device using an electrospray method, in which a voltage is applied between a liquid spraying section and a different pole section that is a different pole to the liquid spraying section, and electrostatic force is generated to cause the liquid to be detached from the liquid spraying section in a charged state, and the atomized liquid is sprayed onto a substrate which is the different pole section. The masking tool comprises a masking body formed of an insulating material, and a masking auxiliary body formed of a conductive material or a semi-conductive material, the masking body is positioned so as not to apply the liquid to the substrate, and is in a charged state to repel the liquid, the masking auxiliary body is positioned so as to define a boundary between a non-coated section of the substrate where the liquid is not applied and a coated section where the liquid is applied, and is at the same potential as the substrate, and the masking body and the masking auxiliary body are positioned in a non-contact state with the substrate.
(2) The masking jig of the present invention is a masking jig used in an electrostatic spraying device using an electrospray method, in which a voltage is applied between a liquid spraying part and a different pole part that is a different pole to the liquid spraying part, and an electrostatic force is generated between the liquid spraying part and the different pole part, causing the liquid to be separated from the liquid spraying part in an electrically charged state, and the atomized liquid is sprayed onto a workpiece that is the different pole part,
A masking aid is provided which is made of a conductive or semiconductive material;
the masking auxiliary body is disposed in a non-contact state with the object to be coated so as to define a boundary between a non-coating portion of the object to which the liquid is not applied and a coating portion to which the liquid is applied,
The masking assistant has a potential of the same polarity as that of the liquid spraying part, and the potential difference between the masking assistant and the workpiece is smaller than the potential difference between the masking assistant and the liquid spraying part.
(3) In the above aspect (2), the potential of the masking assistant is maintained at a potential that allows the atomized liquid atomized by the electrostatic spray device to be applied to the liquid spray portion side of the masking assistant.
(4) In the above embodiment (2) or (3), the potential of the masking assistant is maintained at a potential at which the atomized liquid does not adhere to the side of the masking assistant that faces the object to be coated.
(5) In any one of the above aspects (2) to (4), the masking auxiliary is charged by applying a voltage at least between the liquid spraying portion and the opposite polarity portion, and the potential of the masking auxiliary is maintained by connecting an element having voltage-current characteristics in which the current flowing therethrough increases sharply when a voltage equal to or greater than a certain voltage is applied between the masking auxiliary and the workpiece.
(6) In the above aspect (5), the element is a varistor.
(7) In any one of the above aspects (1) to (6), the masking aid is at the same or longer distance from the application section in the axial direction of the liquid nozzle that sprays the liquid in the liquid spray section.
(8) In any one of the above aspects (1) to (7), the closest part of the edge of the masking auxiliary body on the side of the object to be coated, which is the part that is closest to the object to be coated, is positioned within 10 mm of the object to be coated.
(9) In any one of the above aspects (1) to (8), the masking body and the masking auxiliary body are attached to the liquid spraying section.
(10) In any one of the above aspects (1) to (9), the masking assistant body has a hole portion that defines the application portion, and the area of the hole portion remains the same or increases with increasing distance from the application portion.

The present invention provides a masking jig that can be used for special coating operations such as drawing dots, lines, or pictures, and for coating operations where it is difficult to place a masking jig on the workpiece.

1 is a perspective view showing an overall configuration of an electrostatic spraying device using a masking jig according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing the overall configuration of an electrostatic spraying device using a masking jig according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a liquid spraying section of the electrostatic spraying device. 1A and 1B are enlarged views showing the tip side of the liquid spray part, in which (a) the tip of the mandrel is located at the rear and (b) the tip of the mandrel is located at the front. 1A and 1B are a front view and a cross-sectional view showing a masking jig according to an embodiment of the present invention. FIG. 11 is a cross-sectional view showing a masking jig according to a modified example of the embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a masking jig according to an embodiment of the present invention. 5A and 5B are a front view and a cross-sectional view showing a masking jig according to a second embodiment of the present invention. FIG. 11 is a perspective view showing a masking jig according to a second embodiment of the present invention. FIG. 11 is a cross-sectional view showing a masking jig according to a modified example of the second embodiment of the present invention. FIG. 11 is a perspective view showing a masking jig according to a modified example of the second embodiment of the present invention. 13A and 13B are a front view and a cross-sectional view, respectively, showing a masking jig according to a third embodiment of the present invention. FIG. 13 is a diagram showing voltage changes with and without a constant voltage device. FIG. 13 is a diagram showing the formation of a coating film with and without a constant voltage device. FIG. 11 is a cross-sectional view showing a masking jig according to a third embodiment of the present invention. 13A and 13B are a front view and a cross-sectional view showing a masking jig according to a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description of an embodiment of the present invention will be given with reference to the drawings. Note that the same elements are designated by the same reference numerals throughout the description of the embodiment.
Unless otherwise specified, expressions such as "end" and "front" refer to the side of each component, etc. in the direction in which the liquid is sprayed, and expressions such as "rear" and "rear" refer to the side of each component, etc. opposite the direction in which the liquid is sprayed.

First Embodiment
FIG. 1 is a perspective view showing the overall configuration of an electrostatic spraying device 10 according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the overall configuration of the electrostatic spraying device 10. As shown in FIG.
As shown in Figures 1 and 2, the electrostatic spraying device 10 comprises a liquid spraying section 20 having a liquid nozzle 22, a masking jig 30, and a voltage application means (voltage power supply) 50 that applies a voltage between a different pole section 40 that is a different pole from the liquid spraying section 20.

In this embodiment, the electrical wiring from the voltage application means (voltage power source) 50 is directly connected to the object to be coated, and the object to be coated itself is the opposite pole part 40. However, for example, the electrical wiring from the voltage application means (voltage power source) 50 may be connected to a mounting part (not shown) on which the object to be coated is placed, and the mounting part may be used as the opposite pole part 40, and the object to be coated may be electrically connected to the voltage application means (voltage power source) 50 via the mounting part.

The workpiece to be coated, which becomes the opposite polarity portion 40, is earthed by earthing means 60.
This earthing means 60 is not an essential requirement, but in the case of something like a coating object, it is preferable to provide it from a safety standpoint since there is a possibility that an operator may come into contact with it.

(Liquid spray part)
FIG. 3 is a cross-sectional view showing only the liquid spray unit 20.
In addition, FIG. 3 also illustrates a state in which liquid such as paint is being sprayed from the liquid spray unit 20, as will be described later.
As shown in Figure 3, the liquid spraying unit 20 comprises a body portion 21 made of an insulating material in which a liquid flow path 21b having a liquid supply port 21a through which liquid is supplied is formed, a liquid nozzle 22 provided at the tip of the body portion 21 so that its through hole communicates with the liquid flow path 21b of the body portion 21, and a core rod 23 made of a conductive material arranged within the liquid flow path 21b of the body portion 21 and within the through hole of the liquid nozzle 22.

The body portion 21 has a hole portion 21c communicating with the liquid flow path 21b in order to extract the arbor 23 at the rear end side, and a sealing member 24 is provided within the hole portion 21c to seal the gap between the arbor 23 and prevent liquid from leaking.
In this embodiment, an O-ring is used as the seal member 24, but the seal member is not limited to an O-ring and may be any member capable of sealing.

The rear end of the stem 23, which is located at the rear end of the body 21 through the hole 21c, is provided with a knob 23a made of an insulating material, and an electrical wiring connection 23b made of a conductive material is provided so as to pass through approximately the center of the knob 23a.

As shown in FIGS. 1 and 2, an electric wire from a voltage application means 50 is connected to the electric wire connection portion 23b.
As shown in FIG. 3, the electrical wiring connection portion 23b is brought into contact with the mandrel 23, so that the mandrel 23 and the electrical wiring connection portion 23b are electrically connected to each other.

In this embodiment, the core 23 is used as the electrode on the liquid spray unit 20 side, but for example, the liquid nozzle 22 of the liquid spray unit 20 may be made of a conductive material, and electrical wiring from the voltage application means 50 may be connected to the liquid nozzle 22, so that the liquid nozzle 22 serves as the electrode on the liquid spray unit 20 side.

The inner peripheral surface of the rear end opening 21d of the body 21 is provided with a female thread structure 21e for screwing in the knob 23a, while the outer peripheral surface of the tip of the knob 23a is provided with a male thread structure 23c.

Therefore, the mandrel 23 is removably attached to the body portion 21 by screwing the male thread structure 23c on the outer circumferential surface of the tip of the knob portion 23a into the female thread structure 21e of the rear end opening 21d of the body portion 21.
Furthermore, by adjusting the amount of screwing of the knob 23a, the mandrel 23 can be moved in the front-rear direction, and the position of the tip surface 23d of the mandrel 23 can be adjusted in the front-rear direction.

Generally, the nozzle of an electrostatic spraying device for spraying liquid is a fine liquid flow passage having a small diameter through hole through which the liquid flows.
This is presumably because if the opening diameter of the nozzle tip from which the liquid flows out is large, it becomes difficult to obtain a stable atomization state of the liquid.
For example, the opening diameter of the nozzle tip is generally set to less than 0.1 mm.

As a result, the opening at the tip of the nozzle quickly becomes clogged when the liquid dries, but because the opening diameter is small, it is difficult to unclog the nozzle.

However, for reasons that will be explained later, it has been discovered that by using the mandrel 23, good atomization can be achieved even if the opening diameter at the nozzle tip is made larger than in the past, and for this reason, the opening diameter of the opening 22b at the tip of the liquid nozzle 22 in this embodiment is made to be a large opening diameter of 0.2 mm.
As a result, the frequency with which clogging occurs can be significantly reduced.

The opening diameter of the opening 22b of the liquid nozzle 22 is not limited to 0.2 mm, and in a configuration in which a mandrel 23 is used, there is no problem even if the opening diameter is about 1 mm.

The opening diameter of the opening 22b of the liquid nozzle 22 is preferably 0.1 mm or more, more preferably 0.2 mm or more, and even more preferably greater than 0.2 mm, in order to prevent clogging and to be able to clean even if clogging does occur.

On the other hand, taking into consideration the stability of atomization, the opening diameter of the opening 22b of the liquid nozzle 22 is preferably 1.0 mm or less, more preferably 0.8 mm or less, and even more preferably 0.5 mm or less.

Furthermore, in this embodiment, as described above, the axle 23 can be moved in the forward and backward directions, so that even if clogging occurs, the clogging can be eliminated by moving the axle 23.
Furthermore, the inner diameter of the through hole of the liquid nozzle 22 is large enough to accommodate the mandrel 23, so that the mandrel 23 can be removed and a large amount of cleaning liquid can be poured in to perform cleaning.

Figure 4 is an enlarged view of the tip side of the liquid spray section 20. Figure 4(a) shows the case where the tip surface 23d of the axle 23 is located rearward, and Figure 4(b) shows the case where the tip surface 23d of the axle 23 is located further forward than in the state of Figure 4(a).

As shown in FIG. 4(a), the liquid nozzle 22 has a tapered inner diameter portion (see range A) where the inner diameter tapers toward the opening 22b at a taper angle of α, and the core 23 has a tapered portion (see range B) where the outer diameter tapers toward the tip surface 23d at a taper angle of β.

The taper angle α of the tapered inner diameter portion of the liquid nozzle 22 is set to be larger than the taper angle β of the tapered portion of the stem 23 .
In addition, the diameter of the tip surface 23d of the core rod 23 is smaller than the opening diameter of the opening 22b of the liquid nozzle 22, but the tapered portion of the core rod 23 is formed so that the diameter gradually increases toward the rear end, and has a portion with a diameter larger than the opening diameter of the opening 22b of the liquid nozzle 22.

By forming the tip end of the liquid nozzle 22 and the core rod 23 as described above, as can be seen by comparing Figures 4(a) and 4(b), it becomes possible to adjust the width of the gap formed between the liquid nozzle 22 and the core rod 23 by moving the core rod 23 back and forth, and it is possible to adjust the amount of liquid coming out of the opening 22b of the liquid nozzle 22.

Furthermore, by moving the mandrel 23 further forward than the state shown in Figure 4 (b), the mandrel 23 can abut against the inner surface of the liquid nozzle 22 and block the opening 22b of the liquid nozzle 22.
Therefore, when liquid such as paint is not being sprayed, the opening 22b of the liquid nozzle 22 can be blocked by the core 23, preventing the liquid in the liquid nozzle 22 from drying out, and clogging of the liquid nozzle 22 can be suppressed.

(Other polarity portion 40)
In this embodiment, as described above, a coating object is used as the opposite pole section 40, and the electrical wiring opposite to the one connected to the core 23 of the voltage application means (voltage power source) 50 is connected to the coating object, so that the coating object itself becomes the opposite pole relative to the liquid spray section 20.

However, as mentioned above, for example, when the workpiece is transported by a transport device to a position where a liquid such as paint is to be applied, the electrical wiring from the voltage application means 50 may be connected to a placement section of the transport device on which the workpiece is placed, so that the workpiece is electrically connected to the voltage application means 50 via the placement section.

Next, referring to FIG. 3, we will first explain the state in which liquid is sprayed from the liquid spray unit 20, and then explain the masking jig 30 that ensures that the sprayed liquid is applied only to a specified area of the workpiece.

The liquid supplied to the liquid supply port 21a of the body 21 is supplied to the tip of the liquid nozzle 22, and is pulled forward by the electrostatic force caused by the voltage applied between the opposite pole portion 40 (the object to be coated) and the core 23, causing the liquid to detach and atomize forward.

The liquid supply only needs to be such that the amount of liquid lost from the liquid spray section 20 due to consumption by spraying is supplied in sequence. There is no need to supply the liquid with pressure that would cause the liquid to be sprayed from the opening 22b of the liquid nozzle 22 (more precisely, the gap between the opening 22b and the stem 23). If the liquid is sprayed with too much force, it may actually prevent atomization.

More specifically, the electrostatic force pulling the liquid forward is balanced against the adhesive forces due to surface tension and viscosity on the tip surface 23d of the stem 23 and the tip outer periphery 22a of the liquid nozzle 22, so that the liquid supplied to the tip side of the liquid nozzle 22 forms a Taylor cone 80 at its tip, as shown in Figure 3.

This Taylor cone 80 is formed when the action of an electric field causes separation of positive and negative charges in the liquid, causing the meniscus at the tip of the liquid nozzle 22, which is charged with excess electric charge, to deform into a cone shape.
The liquid is then pulled straight from the tip of the Taylor cone 80 by electrostatic force, and the liquid explodes electrostatically at the tip of the jet portion 82 that extends linearly from the tip of the Taylor cone 80, causing the liquid to spray over a wide area.

The liquid being sprayed, that is, the liquid that has left the liquid nozzle 22 and become liquid particles, has a significantly larger surface area exposed to the air than before it left the nozzle, accelerating the evaporation of the solvent. As the solvent evaporates, the distance between the charged electrons decreases, causing electrostatic repulsion (electrostatic explosion), which then breaks up into smaller liquid particles.

When this splitting occurs, the surface area exposed to the air increases compared to before the splitting, accelerating the evaporation of the solvent, causing an electrostatic explosion as described above, and further splitting into liquid particles with smaller diameters.
Such electrostatic explosions are repeated to atomize the liquid.

In this embodiment, a stem 23 is provided within the liquid nozzle 22 .
If the core 23 were not provided as in the conventional electrostatic spraying device, the only part to which the liquid could adhere would be the outer circumferential edge 22a at the tip of the liquid nozzle 22.

If the opening diameter of the opening 22b of the liquid nozzle 22 is increased in this state, the only part to which the liquid can adhere is the outer peripheral edge 22a at the tip of the liquid nozzle 22, so that, for example, the liquid is likely to sway up, down, left, and right of the liquid nozzle 22, making it impossible to form a clean Taylor cone 80, and the Taylor cone 80 itself cannot be maintained, so stability of the liquid particles detaching from the liquid nozzle 22 (stability of particle size, number, charge state, etc.) cannot be obtained, and as a result, it is presumed that stable atomization of the liquid cannot be achieved.

On the other hand, in this embodiment, a mandrel 23 is disposed inside the liquid nozzle 22 , and the liquid adheres not only to the outer circumferential edge 22 a of the tip of the liquid nozzle 22 , but also to the tip surface 23 d of the mandrel 23 .
Therefore, even if the opening diameter of the opening 22b of the liquid nozzle 22 is large, since there is a tip surface 23d of the core 23 to which the liquid can adhere in the center of the opening 22b, a stable Taylor cone 80 can be formed, thereby enabling stable atomization of the liquid.

If the tip surface 23d of the stem 23 extends too far forward from the tip outer periphery 22a of the liquid nozzle 22 (i.e., the tip surface of the opening 22b of the liquid nozzle 22), it becomes difficult for the electric field to act on the liquid coming out of the liquid nozzle 22. On the other hand, if the tip surface 23d of the stem 23 recedes too far back from the tip surface of the opening 22b of the liquid nozzle 22, it will be the same as if there is no part in the center of the opening 22b where the liquid can adhere.

For this reason, when the liquid is being sprayed, the position of the tip surface 23d of the mandrel 23 is preferably located within 10 times, more preferably within 5 times, and even more preferably within 3 times the opening diameter of the opening 22b at the tip of the liquid nozzle 22 in the front-to-rear direction along the central axis of the mandrel 23, based on the tip surface of the opening 22b of the liquid nozzle 22.

For example, in this embodiment, the opening diameter of the opening 22b of the liquid nozzle 22 is 0.2 mm, and if electrostatic forces are not taken into consideration, the liquid coming out of the opening 22b of the liquid nozzle 22 comes out in a hemispherical shape with a diameter of approximately 0.2 mm at the tip of the liquid nozzle 22.

The tip of the axle 23 should be located near the liquid so that an electric field (electrostatic force) acts on the liquid coming out of the tip of the liquid nozzle 22 to form a conical Taylor cone 80. For this reason, it is preferable to position the tip of the axle 23 within 2 mm forward (in the outgoing direction) from the tip surface of the opening 22b of the liquid nozzle 22. On the other hand, it is preferable to position the tip of the axle 23 within 2 mm backward (in the retracting direction) from the tip surface of the opening 22b of the liquid nozzle 22 so that it acts on the adhesion of the liquid.

As described above, by providing the core rod 23, stable atomization of the liquid can be achieved even if the opening diameter of the opening 22b of the liquid nozzle 22 is increased.
Therefore, the opening diameter of the opening 22b of the liquid nozzle 22 can be made large enough to prevent clogging.
Furthermore, since the opening diameter of the opening 22b of the liquid nozzle 22 can be made large, the liquid nozzle 22 can be manufactured by machining.

In this embodiment, the tip of the axle 23 has a flat surface as the tip surface 23d, but the tip of the axle 23 does not necessarily have to be a flat surface, and as long as it contributes to the formation of a stable Taylor cone 80, the tip of the axle 23 may be a curved surface that protrudes forward, such as an R-shape.

In this way, the liquid sprayed from the liquid spray unit 20 (liquid nozzle 22) becomes an atomized liquid through repeated electrostatic explosions, and because this atomized liquid is in an electrically charged state, it is attracted by electrostatic force to the opposite pole unit 40 (subject to be coated) and is applied to the subject to be coated.

(Masking jig)
As shown in FIGS. 1 and 2, the masking jig 30 includes a masking body 31 made of an insulating material, and a masking auxiliary body 32 .
In this embodiment, the object to be coated constitutes the opposite polarity portion 40, and therefore in describing the object to be coated, the same reference numerals as those used for the opposite polarity portion will be used for the object to be coated 40 in the following description.

The masking assistant 32 has a circular hole 32a in the center for allowing the sprayed liquid to pass through.
That is, this embodiment illustrates a case where the liquid is applied in a circular shape onto the substrate 40. The shape of the holes 32a can be freely selected according to the pattern to be drawn on the substrate 40, and can be any shape, such as a circle, a triangle, a polygon, or the like.

Here, as shown in Figure 2, the masking auxiliary body 32 defines a boundary 43 between a coating portion 41 of the workpiece 40 to which the liquid is applied and a non-coating portion 42 of the workpiece 40 to which the liquid is not applied.
That is, in the masking jig 30 , the masking assistant 32 is arranged so as to define a boundary 43 between the coated portion 41 and the non-coated portion 42 .

As shown in Figure 2, the masking body 31 is positioned on the workpiece 40 so as not to apply liquid to at least certain parts of the non-coated portion 42 of the workpiece 40 that are not covered by the masking auxiliary body 32 on the non-coated portion 42 side of the boundary 43.
In other words, in the masking jig 30, the masking body 31 is positioned so as to cover at least a certain portion of the non-coated portion 42 of the workpiece 40 that is not covered by the masking auxiliary body 32 on the non-coated portion 42 side of the boundary 43.

In this embodiment, the masking jig 30 is positioned so as to be out of contact with the workpiece 40. In other words, neither the masking body 31 nor the masking auxiliary body 32 comes into contact with the workpiece 40, and this is the same whether the masking body 31 is located closer to the workpiece 40 or the masking auxiliary body 32 is located closer to the workpiece 40.

As can be seen from the exploded cross-sectional views of the masking jig 30 shown in Figures 1 and 2, the masking jig 30 of this embodiment is formed with the masking auxiliary body 32 and the masking body 31 formed separately, and the masking auxiliary body 32 is attached to the masking body 31 in a removable or inaccessible manner.

FIG. 5 shows a masking jig 30 according to an embodiment of the present invention, where (a) is a front view and (b) is a cross-sectional view.
In the embodiment shown in FIG. 5, the masking auxiliary 32 is disposed on the side closer to the liquid spraying unit 20, and the masking body 31 is disposed on the side closer to the workpiece 40 so as to be in a non-contact state with the workpiece 40. In this way, both the masking body 31 and the masking auxiliary 32 are disposed with a gap between them, so that when performing a liquid coating operation, the workpiece 40, the liquid spraying unit 20, and the masking jig 30 can be moved relative to each other. By coating while changing the positional relationship between the liquid spraying unit 20 and the masking jig 30 without changing the positional relationship between the liquid spraying unit 20 and the workpiece 40, various coating operations can be performed. For example, special coating operations such as drawing dots, lines, or pictures can be performed.
As long as relative movement is possible, the workpiece 40 may be fixed and the liquid spraying unit 20 and masking jig 30 may be moved simultaneously without changing their relative positions, or the liquid spraying unit 20 and masking jig 30 may be fixed and the workpiece 40 may be moved.

In addition, by positioning the masking jig 30 so that it is not in contact with the workpiece 40, it becomes possible to perform precise coating work using the masking jig 30 even on workpieces on which a masking jig cannot be placed when the masking jig is placed in contact with the workpiece as in the past. For example, even on workpieces 40 with uneven surfaces or curved surfaces, the masking jig 30 of this embodiment can be appropriately positioned to perform coating work.

As described above, the masking body 31 is made of an insulating material, such as polyethylene, polypropylene, polyphenylene sulfide, polyethylene terephthalate, or a fluorine-based resin.
The masking body 31 is formed to have a thickness equal to or greater than a predetermined thickness so that the surface becomes charged in the same state as the liquid being sprayed due to the electrostatic force generated by the voltage applied between the workpiece 40 and the liquid spray section 20 (i.e., if the liquid is positively charged, the surface becomes positively charged, and if the liquid is negatively charged, the surface becomes negatively charged).

For example, the predetermined thickness is preferably 0.5 mm or more, and more preferably 1.0 mm or more.
In this way, by increasing the thickness to facilitate polarization, the masking body 31 can easily attain a favorable charged state that repels charged liquid, thereby preventing or reducing the application of liquid onto the masking body 31.
Therefore, the number of times the masking body 31 needs to be washed can be significantly reduced.

Although the masking body 31 is designed to make it difficult for liquid to be applied, it does not completely prevent liquid from being applied.

For example, some liquid may be transferred during the application process, and when the application process is completed and the electrostatic force is no longer generated, liquid floating around the area may be transferred.

For this reason, the masking body 31 is exposed to solvents and the like, and is therefore preferably formed using an insulating material that has excellent solvent resistance.
From this viewpoint, it is therefore preferable to use a material having excellent solvent resistance, such as polyethylene, polypropylene, polyphenylene sulfide, polyethylene terephthalate, or a fluorine-based resin, for the masking body 31 .

On the other hand, the masking assistant 32 is made of a conductive material or an antistatic material with a surface resistance of 10 ¹⁰ Ω or less so that the sprayed liquid can be applied to it. The conductive material forming the masking assistant 32 is preferably a metal such as copper or aluminum, and the semiconductive material is preferably a resin mixed with a conductive substance such as carbon or a metal.

As shown in FIG. 5, the masking auxiliary body 32 is connected to the opposite pole of the voltage application means 50 from the liquid spray section 20 and to the same pole as the workpiece 40, so it can be considered to be at the same potential as the workpiece 40.

As a result, the sprayed liquid is not collected in the center of the hole 32a of the masking auxiliary body 32 due to electrostatic repulsion, and the liquid sprayed onto the masking auxiliary body 32 that is outside the hole 32a is applied onto the masking auxiliary body 32, while the liquid sprayed onto the hole 32a reaches the top of the workpiece 40.

FIG. 7 is an enlarged cross-sectional view showing a masking jig 30 according to an embodiment of the present invention.
7, the masking auxiliary body 32 is disposed with a gap P from the workpiece 40. The masking main body 31 is disposed with a gap from the workpiece 40 while in contact with the masking auxiliary body 32. An opening 31a larger than the hole 32a is disposed in the masking auxiliary body 32 so that the masking main body 31 does not block the hole 32a and so that the liquid sprayed by the electrostatic charge at the edge of the masking main body 31 is not pushed aside.

In this state, the liquid sprayed from the liquid spraying section 20 is in an electrically charged state and proceeds as shown in FIG. 7, as shown in spray liquid 87a, 87b, 87c, and 87d. Spray liquid 87a, which has proceeded straight from the liquid nozzle 22, passes through the center of the hole 32a and proceeds straight without being affected by it, and reaches the workpiece 40. Spray liquid 87b, which has proceeded closer to the inner edge of the hole 32a than the spray liquid 87a, is slightly attracted to the masking auxiliary body 32, which is the opposite pole to the liquid, and its direction of travel is bent to reach the workpiece 40. Spray liquid 87c, which passes right next to the inner edge of the hole 32a, is attracted to the masking auxiliary body 32 and changes its direction of travel by about 180°, reaching the side of the masking auxiliary body 32 closer to the workpiece 40. Spray liquid 87d, which has flowed outside the hole 32a, is attracted to the masking auxiliary body 32 and reaches the masking auxiliary body 32 as it is. Then, the sprayed liquids 87a and 87b that reach the workpiece 40 form a coating film 85.

The masking jig 30 and the object 40 are arranged in a non-contact state, which affects the formation of the coating film 85 having the same shape as the hole 32a provided in the masking auxiliary 32, i.e., the accurate formation of the boundary 43 between the non-coated portion 42 and the coated portion 41. That is, in FIG. 7, when the gap P between the closest portion 32b, which is the portion closest to the object 40, and the object 40 is large around or on the edge of the hole 32a of the masking auxiliary 32, the spray liquid 87b advances further outward and reaches the object 40. In this case, the coating film 85 is formed outside the edge of the hole 32a, and becomes larger than the hole 32a, decreasing the accuracy of the boundary 43 between the non-coated portion 42 and the coated portion 41. Therefore, in order to form a coating film 85 with high accuracy, there is an upper limit to the gap P, which is 20 mm or less, preferably 10 mm or less, and more preferably 5 mm or less.
In FIG. 7, the workpiece 40 and the masking auxiliary body 32 are planar and arranged in parallel, so that the closest portion 32b is the entire periphery or edge of the hole portion 32a.

In addition, in FIG. 7, if the amount of protrusion Q of the edge of the hole 32a of the masking auxiliary 32 protruding inward relative to the edge of the opening 31a provided in the masking body 31 is large, the effect of attracting the sprayed liquid becomes large, and the sprayed liquid 87b that should reach the workpiece 40 is attracted to the masking auxiliary 32 before it reaches the workpiece 40, and reaches the side of the masking auxiliary 32 closer to the workpiece 40, just like the sprayed liquid 87c. As a result, the coating film 85 becomes smaller than the hole 32a, and the accuracy of the boundary 43 between the non-coated portion 42 and the coated portion 41 decreases. Therefore, in order to form a highly accurate coating film 85, there is an upper limit to the amount of protrusion Q, which is preferably 10 mm or less, and more preferably 5 mm or less.

In this embodiment, the masking body 31 is exemplified as a flat plate, but the shape of the masking body 31 itself is arbitrary, and the shape of the plate may be curved to match the shape of the object 40 to be coated.
Furthermore, the thickness of the masking body 31 does not need to be uniform, but it is sufficient that the thickness is sufficient to prevent or reduce the liquid from being applied.

FIG. 6 is a cross-sectional view showing a masking jig 30 according to a modified example of the embodiment of the present invention.
In Fig. 6, unlike the case shown in Fig. 5, the masking body 31 is arranged closer to the liquid spraying part 20, and the masking auxiliary body 32 is arranged closer to the workpiece 40 so as to be in a non-contact state with the workpiece 40. In this way, both the masking body 31 and the masking auxiliary body 32 are arranged in a non-contact state with a gap between them and the workpiece 40, and it is possible to move the workpiece 40 relative to the liquid spraying part 20 and the masking jig 30, just like the case shown in Fig. 5.
Similarly, the masking body 31 is made of an insulating material, and the masking assistant body 32 is made of a conductive material or an antistatic material having a surface resistance of 10 ¹⁰ Ω or less.

As shown in Figure 6, the masking auxiliary body 32 is connected to the opposite pole of the liquid spray section 20 in the voltage application means 50 and to the same pole as the workpiece 40, and therefore can be considered to be at the same potential as the workpiece 40.
In addition, the masking body 31 is formed to have a thickness equal to or greater than a predetermined thickness so that the surface is charged in the same state as the liquid to be sprayed by the electrostatic force generated by the voltage applied between the workpiece 40 and the liquid spraying unit 20 (that is, if the liquid is positively charged, the surface is positively charged, and if the liquid is negatively charged, the surface is negatively charged). In the configuration shown in FIG. 6, the masking body 31 is disposed on the side closer to the liquid spraying unit 20, but the repulsive force generated by the charge state of the same polarity as the liquid to be sprayed can prevent or reduce the liquid from being applied onto the masking body 31. In addition, the masking body 31 covers the masking auxiliary body 32 disposed on the side closer to the workpiece 40, so that the liquid can be prevented from being applied onto the masking auxiliary body 32. For this reason, it is possible to significantly reduce the number of times the masking body 31 and the masking auxiliary body 32 are washed.

The masking body 31 is placed in contact with the masking auxiliary body 32, but also in a non-contact state with a gap between it and the workpiece 40. An opening 31a larger than the hole 32a is placed in the masking auxiliary body 32 so that the masking body 31 does not block the hole 32a.

In FIG. 7, the sprayed liquid 87c passing just beside the inner edge of the hole 32a is attracted to the masking auxiliary 32, changes its direction of travel by approximately 180°, and reaches the side of the masking auxiliary 32 closer to the workpiece 40. However, in the configuration of FIG. 6, if the entire surface of the masking auxiliary 32 facing the workpiece 40 is exposed, more liquid will adhere to the surface of the masking auxiliary 32 facing the workpiece 40. In other words, the liquid passing inside the sprayed liquid 87c at the edge of the hole 32a will also adhere to the surface of the masking auxiliary 32 facing the workpiece 40, making it difficult to accurately form the boundary 43 between the non-coated portion 42 and the coated portion 41.

For this reason, in a modified version of this embodiment, an insulating back cover 34 made of the same insulating material as the masking body 31 is placed on the side of the masking auxiliary body 32 facing the workpiece 40 so as not to come into contact with the workpiece 40. An opening 34a larger than the hole 32a is placed on the insulating back cover 34 so as not to block the hole 32a and so as not to push away the liquid sprayed by the charging of the edge of the masking body 31. The dimensions of this opening 34a relative to the hole 32a are determined so that the protrusion amount is the same as the protrusion amount Q in Figure 7.

In a modified example of this embodiment, it is possible to form the boundary 43 between the non-coated portion 42 and the coated portion 41 with a high degree of precision, similar to the configuration shown in Figure 5, and furthermore, it is possible to reduce the amount of liquid adhering to the masking body 31 and the masking auxiliary body 32, thereby eliminating waste of liquid and significantly reducing the number of times the masking body 31 and the masking auxiliary body 32 need to be cleaned.
In addition, the masking jig 30 is positioned in a non-contact state with the workpiece 40 and can be moved relatively to perform special coating operations such as drawing dots, lines or pictures. Even if the workpiece has an uneven surface or is composed of a curved surface, the masking jig 30 of this embodiment can be appropriately positioned to perform coating operations.

Second Embodiment
The second embodiment will be described below.
In the second embodiment, the basic configuration (configuration having a liquid spray section 20, a different electrode section 40 (substrate), and a masking jig 130) is the same as in the first embodiment, but the masking body 131 and the masking auxiliary body 132 of the masking jig 130 are different.

8A and 8B are a front view and a cross-sectional view, respectively, showing a masking jig according to a second embodiment of the present invention.
FIG. 9 is a perspective view showing a masking jig according to the second embodiment of the present invention.
The second embodiment will be described with reference to FIG. 8 and FIG.

As shown in Figure 8, the masking body 131 has a truncated cone shape, and is hollow and made of an insulator having a thickness equal to or greater than a predetermined thickness, similar to the masking body shown in Figure 5, with an opening 131a provided on the side closer to the workpiece 40. The side closer to the workpiece 40 is the small diameter end 131c, and the side closer to the liquid spray section 20 is the large diameter end 131d, which are connected by a side surface 131e. In other words, the distance to the masking body 131 increases in the direction perpendicular to the axis of the liquid nozzle 22 as it moves from the workpiece 40 toward the liquid spray section 20.

The masking auxiliary body 132 has a truncated cone shape like the masking body 131, is hollow and made of a thin plate-shaped conductive material or an antistatic material with a surface resistance of 10 ¹⁰ Ω or less, and has a hole 132a on the side closer to the workpiece 40. The side closer to the workpiece 40 is a small diameter end 132c, and the side closer to the liquid spraying section 20 is a large diameter end 132d, which are connected by a side surface 132e. In other words, the distance to the masking auxiliary body 132 becomes longer in the direction perpendicular to the axis of the liquid nozzle 22 as it moves from the workpiece 40 toward the liquid spraying section 20. When the hole 132a is formed in the entire small diameter end 132c, it can also be considered that the area of the hole 132a becomes larger as it moves away from the workpiece 40 toward the liquid spraying section 20.
In the masking auxiliary body 132, the small diameter end portion 132c which surrounds or forms the edge of the hole portion 132a corresponds to the closest portion which is the portion which is closest to the workpiece 40, but the small diameter end portion 132c is not in contact with the workpiece 40 and is positioned at a distance of 20 mm or less, preferably 10 mm or less, and more preferably 5 mm or less, which is similar to the configuration shown in Figure 7.
The masking aid 132 has a hole 132a in the center through which the sprayed liquid passes, and the shape of the hole 132a can be freely selected depending on the pattern desired to be drawn on the substrate 40; for example, it can be any shape, such as a circle, a triangle, a polygon, or the like.
8, the masking auxiliary body 132 is configured to have a truncated cone shape, but is not limited thereto, and may be, for example, a polygonal truncated pyramid shape, a cylindrical shape, or a flat or curved surface that does not form a hole. In the case of a cylindrical shape, the hole 132a has the same diameter even when it is away from the workpiece 40. Similarly, the inner peripheral length of the perpendicular cross section of the masking auxiliary body 132 with respect to the central axis of the hole 132a also remains the same length even when it is away from the workpiece 40.

The apex angles of the truncated cone shapes of the masking main body 131 and the masking auxiliary body 132 are the same. In addition, the large diameter end 132d of the masking auxiliary body 132 is configured to be larger than the small diameter end 131c of the masking main body 131. Therefore, when the masking auxiliary body 132 is inserted from the large diameter end 131d side of the masking main body 131 with the small diameter end 132c at the head, the large diameter end 132d and the side surface 132e in the vicinity thereof come into contact with the side surface 131e, and the masking auxiliary body 132 is fitted into the masking main body 131 to become one body.
In the embodiment shown in FIG. 8, a support member 140 is connected at three points to a portion of the side surface 131e of the masking body 131 near the large diameter end portion 131d, and the rear end thereof is connected to a mounting member 141 to be integrated therewith.
The mounting member 141 has a through hole with approximately the same diameter as the outer diameter of the liquid nozzle 22, and the liquid nozzle 22 is fitted into this through hole and fixed.
That is, the masking main body 131 and the masking auxiliary body 132, which are integrated in a fitted state, are fixed to the liquid nozzle 22 via the support member 140 and the mounting member 141, whereby the masking jig 130 is attached to the liquid spray section 20 to form an integrated structure.
In this embodiment, the opening 131a of the masking body 131, the hole 132a of the masking assistant body 132, and the central axis of the liquid nozzle 22 of the liquid spray unit 20 are configured to be concentric.

The masking body 131 and the masking auxiliary body 132 may simply be fitted together or may be bonded together, or may be molded integrally with each other, with the masking body 131 being made of insulating resin and the masking auxiliary body 132 being made of conductive resin.
The support member 140 and the mounting member 141 may be integrally molded by molding a resin material or by die casting a metal material.
The mounting member 141 and the liquid nozzle 22 may be integrated together by a press-fit structure or by adhesive.

In this way, by integrating the masking jig 130 and the liquid spray unit 20, the masking jig 130 and the liquid spray unit 20 can be moved together relative to the workpiece 40, and the coating film 85 defined by the hole 132a of the masking auxiliary body 132 can be used as a reference unit to apply various shapes by combining these reference units. In other words, special application work such as drawing dots, lines, or pictures can be performed.

In addition, even for workpieces on which the masking jig 30 cannot be placed when the masking jig 30 is in contact with the workpiece 40 as in the conventional configuration, precise coating work can be performed using the masking jig 130. For example, even for workpieces with uneven surfaces or curved surfaces, the masking jig 30 of this embodiment can be appropriately positioned to perform coating work. When the workpiece 40 has uneven surfaces, the masking jig 130 and the liquid spray unit 20 can be moved three-dimensionally, including forward and backward, as a single unit, to perform coating work.

The surface of the masking body 131 is in an electrically charged state similar to that of the liquid sprayed from the liquid spraying unit 20 due to electrostatic force.
On the other hand, as shown in Figure 8 (b), the masking auxiliary body 132 is connected to the opposite pole of the liquid spray section 20 in the voltage application means 50 and to the same pole as the workpiece 40, and therefore can be considered to be at the same potential as the workpiece 40.

Because the masking body 131 is configured in a truncated cone shape, the main flow of atomized liquid flowing near the center proceeds forward without being influenced by the masking body 131 and comes close to the masking auxiliary body 132. Because the masking auxiliary body 132 is also configured in a truncated cone shape, the atomized liquid within the same diameter range as the hole 132a reaches the hole 132a without being influenced by the masking auxiliary body 132 until it comes close to the hole 132a, and then passes through the hole 132a to reach the workpiece 40 and form the coating film 85.
Since the side surface 132e of the masking auxiliary body 132 facing the workpiece 40 is inclined with respect to the central axis of the liquid nozzle 22 of the liquid spray section 20, the atomized liquid passing near the inner edge of the hole portion 132a travels almost straight without being affected by the masking auxiliary body 132, reaches the workpiece 40 and forms a coating film 85, and a highly precise coating film 85 can be formed on the hole portion 132a.

That is, in FIG. 7, the spray liquid 87c passing just beside the inner periphery of the hole 32a is attracted to the masking auxiliary body 32, changes its direction of travel by approximately 180°, and reaches the side of the masking auxiliary body 32 closer to the workpiece 40, but in the second embodiment shown in FIG. 8, when the liquid passes the inner periphery of the hole 132a, the wall surface of the masking auxiliary body 132 on the side of the workpiece 40 is in a position away from it, so there is almost no liquid behaving in this way.

On the other hand, when the liquid sprayed from the liquid spray unit 20 comes near the masking body 131, it floats without adhering to the masking body 131 due to the repulsive force, is pulled toward the center, and proceeds forward until it comes near the masking auxiliary body 132. Then, some of this liquid adheres to the masking auxiliary body 132, but some reaches the hole portion 132a, and reaches the coated object 40 as it is to form the coating film 85.
Therefore, the amount of liquid adhering to the masking body 31 and the masking auxiliary body 32 is reduced, eliminating waste of liquid and making it possible to significantly reduce the number of times the masking body and the masking auxiliary body 132 need to be washed.

FIG. 10 is a cross-sectional view showing a masking jig 130 according to a modified example of the second embodiment of the present invention, and FIG. 11 is a perspective view thereof.
A modification of the second embodiment will be described with reference to FIGS.
10 and 11, in a modification of the second embodiment, the masking body 131 and the masking auxiliary body 132 are each formed of two separate plate-like objects, and are arranged so that the distance between the two plate-like objects in the direction perpendicular to the axis of the liquid nozzle 22 becomes the same or longer as the distance from the workpiece 40 increases in the axial direction of the liquid nozzle 22. The surface of the masking body 131 is in an electrically charged state similar to that of the liquid sprayed from the liquid spraying section 20 due to electrostatic force, and the masking auxiliary body 132 is in a state that can be considered to be at the same potential as the workpiece 40.

There is no hole with a closed perimeter equivalent to the opening 131a or the hole 132a, and the closest parts of the two plate-like objects closest to the workpiece 40 and the space therearound perform the same function as the opening 131a or the hole 132a. That is, the closest parts 132b of the two masking auxiliary bodies 132 to the workpiece 40 are arranged so as to define the boundary 43 between the coated part 41 and the non-coated part 42 shown in FIG. 2. The closest parts 132b are not in contact with the workpiece 40, and are arranged at a distance of 20 mm or less, preferably 10 mm or less, and more preferably 5 mm or less, as in the configuration shown in FIG. 7.

Even in the modified example of the second embodiment, the two plate-like objects are arranged so that the distance between them in the direction perpendicular to the axis of the liquid nozzle 22 is the same or longer as they move away from the workpiece 40 in the axial direction of the liquid nozzle 22. This allows the atomized liquid passing near the closest part 132b of the masking auxiliary body 132 to the workpiece 40 to travel in an almost straight line without being affected by the masking auxiliary body 132 and reach the workpiece 40 to form the coating film 85, thereby forming a highly accurate coating film 85.

As shown in FIG. 11, the masking jig 130 is formed by a masking body 131 and a masking auxiliary body 132, each of which is made of a plate-like material, in a state of close contact. They may be bonded to each other, or may be integrally molded with the masking body 131 being made of insulating resin and the masking auxiliary body 132 being made of conductive resin. In addition, by fixing it to the liquid nozzle 22 via a support member and an attachment member (not shown), the masking jig 130 is attached to the liquid spray unit 20 in the same way as in the case shown in FIG. 9, and becomes an integral structure.

As shown in FIG. 11, the masking body 131 and the masking auxiliary body 132 may be formed of two flat plate-like objects, but are not limited to this and may be shaped, for example, with curved surfaces or a combination of curved and flat surfaces. This makes it possible to provide a masking jig 130 that is most suitable for the various coating contents to be performed on various objects 40.

Third Embodiment
The third embodiment will now be described.
12A and 12B show a masking jig 230 according to a third embodiment of the present invention, where (a) is a front view and (b) is a cross-sectional view.
In the third embodiment shown in FIG. 12, a masking jig 230 differs from that in the first embodiment in that a constant voltage device 251 is connected to a masking assistant body 232 .
The masking assistant 232 is similar to that in the first embodiment in that it is made of a conductive material, a semiconductive material having a surface resistance of 10 ¹⁰ Ω or less, or an antistatic material.
The masking auxiliary body 232 defines a coating area in the center and has a hole 232a through which the sprayed liquid passes, and the shape of the hole 232a can be freely selected according to the pattern to be drawn on the workpiece 40, and can be any shape, such as a circle, a triangle, a polygon, or the like, as in the first embodiment.

In addition, in Figures 12 and 14, the masking jig 230 has a masking auxiliary body 232 but does not have a masking body. In this embodiment, the masking jig may or may not have a masking body.

When a masking body is provided, it is arranged, has a role, and is made of the same material as in the first embodiment shown in Fig. 2. That is, the masking body is arranged on the workpiece 40 so as not to apply liquid to certain parts of the non-coated portion of the workpiece 40 that is not covered by the masking auxiliary body 232. The masking body is arranged so as not to apply the atomized liquid to the workpiece 40, is in an electrically charged state that repels the atomized liquid, and is arranged in a non-contact state with the workpiece 40.
The masking body is made of an insulating material, similar to the first embodiment, such as polyethylene, polypropylene, polyphenylene sulfide, polyethylene terephthalate, or fluorine-based resin.

An element having a voltage-current characteristic in which the current flowing increases rapidly when a voltage equal to or greater than a certain voltage is applied can be used as the constant voltage device 251. In particular, an element having a characteristic in which no current flows or even if it flows, it is an extremely small current up to a certain voltage, but the current flowing increases rapidly when the voltage exceeds the certain voltage is preferable.
An example of an element that exhibits such characteristics is a varistor. As a varistor is sometimes called a nonlinear resistor or a voltage-dependent resistor, it has a characteristic in which the internal resistance drops suddenly when a certain voltage is applied, and as a result, it is an element that has a voltage-current characteristic in which the current that flows increases rapidly when a voltage above a certain voltage is applied. Varistors are generally used as surge protection devices (SPDs) to prevent high voltages such as lightning surges, static electricity, and back electromotive voltages when the power supply to DC equipment (DC motors, etc.) is cut off from flowing into a circuit, and to protect each element of the circuit and electronic equipment.

In the third embodiment, the varistor is not used to protect each element of such a circuit or electronic device, but to set the potential of the masking auxiliary 232 to have the same polarity as the liquid spraying unit 20 and to set the potential difference between the masking auxiliary 232 and the workpiece 40 smaller than the potential difference between the masking auxiliary 232 and the liquid spraying unit 20, or to maintain the potential of the masking auxiliary 232 at a potential at which the atomized liquid atomized by the electrostatic spraying device 10 can be applied to the liquid spraying unit 20 side of the masking auxiliary 232, or to maintain the potential of the masking auxiliary 232 at a potential at which the atomized liquid does not adhere to the workpiece 40 side of the masking auxiliary 232. In addition, the multilayer chip varistor has a structure similar to a capacitor with a metal oxide sandwiched between electrodes, and has a capacitance component, i.e., a function of storing electric charge like a capacitor, and is therefore suitable for use in the constant voltage device 251 in this embodiment in that it has the effect of suppressing sudden changes in voltage.

12, when the voltage application means 50 is turned on, electric charge accumulates in the liquid spraying part 20, and a potential difference occurs between the liquid spraying part 20 and the masking assistant 232 to which the negative electrode of the voltage application means 50 is connected. This potential difference increases as electric charge accumulates in the liquid spraying part 20.
Then, by turning on the power supply of the voltage application means 50, that is, by applying a voltage at least between the liquid spraying part 20 and the workpiece 40 which is the opposite polarity part, the masking auxiliary body 232 is charged. The masking auxiliary body 232 is charged by the action of the atomized liquid sprayed from the liquid spraying part 20 by turning on the power supply of the voltage application means 50 and by discharge from the liquid spraying part 20. This discharge is not limited to that generated by the liquid spraying part 20. It may be configured so that the discharge occurs from an electrode provided near the liquid spraying part 20 and having the same polarity as the liquid spraying part 20.

When the constant voltage device 251 is not connected to the masking auxiliary body 232, the potential difference between the liquid spraying unit 20 and the masking auxiliary body 232 increases as charge accumulates in the liquid spraying unit 20. The voltage of the masking auxiliary body 232 is not equal to the power supply voltage because of its own discharge, and it is charged to the voltage between the positive and negative poles of the voltage application means 50.

In contrast, as shown in FIG. 12, when the constant voltage device 251 is connected to the masking auxiliary 232, the masking auxiliary 232 becomes charged, and when the potential of the masking auxiliary 232 based on the negative electrode of the voltage application means 50, i.e., the voltage applied to both ends of the constant voltage device 251, reaches a certain voltage (rated voltage) or higher set by the rating of the constant voltage device 251, the internal resistance of the constant voltage device 251 drops suddenly, etc., causing the current flowing through the path from the liquid spray unit 20 to the constant voltage device 251 via the masking auxiliary 232 to increase rapidly, and acts to maintain the potential of the masking auxiliary 232 based on the negative electrode of the voltage application means 50, i.e., the voltage applied to both ends of the constant voltage device 251, at the rated voltage of the constant voltage device 251.

Figure 13 shows the change in voltage with respect to the workpiece 40 when the workpiece is connected to earth with and without the constant voltage device 251. Figure 13(a) shows the change in voltage of the liquid spray section 20 when the constant voltage device 251 is not present, and Figure 13(b) shows the change in voltage of the masking auxiliary body 232 when the constant voltage device 251 is present.

In FIG. 13(a), when the voltage application means 50 is turned on, charge is stored in the liquid spraying part 20 and the potential gradually rises. When the potential rises to around 9 kV due to the balance between the charge from the liquid spraying part 20 and the discharge of the masking auxiliary body 232 itself, this potential is maintained at approximately this level.

13(b), when the power supply for the voltage application means 50 is turned on, electric charge is stored in the liquid spraying section 20 and the voltage gradually rises, which in turn charges the masking auxiliary body 232 and raises the potential of the masking auxiliary body 232. When the potential of the masking auxiliary body 232 with respect to the negative electrode of the voltage application means 50, i.e., the voltage applied across the constant voltage device 251, approaches 5 kV, which is the rated voltage of the constant voltage device 251, the internal resistance of the constant voltage device 251 drops sharply, causing the flowing current to increase sharply, and the voltage becomes substantially constant at around 5 kV.
By connecting the constant voltage device 251 to the masking auxiliary body 232, the potential of the masking auxiliary body 232 relative to the negative electrode of the voltage application means 50 becomes equal to the voltage across the constant voltage device 251, i.e., the rated voltage of the constant voltage device 251.

The workpiece 40 is connected to the negative electrode of the voltage application means 50, and the workpiece 40 is at the same potential as the negative electrode of the voltage application means 50. Therefore, the potential difference between the liquid spray section 20, which is connected to the positive electrode of the voltage application means 50, and the workpiece 40 is equal to the power supply voltage of the voltage application means 50, regardless of whether the constant voltage device 251 is connected to the masking auxiliary body 232.

On the other hand, when the constant voltage device 251 is connected to the masking auxiliary body 232, the potential of the liquid spraying section 20 is the highest, followed by the masking auxiliary body 232, and the workpiece 40 is the lowest. The potential difference between the masking auxiliary body 232 and the workpiece 40 is the rated voltage of the constant voltage device 251. In other words, when the workpiece 40 is taken as the reference potential, the masking auxiliary body 232 has a positive potential and has the same polarity as the liquid spraying section 20.

Therefore, when a constant voltage device 251 is connected to the masking auxiliary body 232, the potentials of the liquid spray section 20, the masking auxiliary body 232, and the workpiece 40 can be set to a predetermined relationship by selecting the power supply voltage of the voltage application means 50 and the rated voltage of the constant voltage device 251.
In this embodiment, it is preferable that the potential of the masking assistant 232 be set to the same polarity as that of the liquid spraying section 20 and that the potential difference between the masking assistant 232 and the workpiece 40 is smaller than the potential difference between the masking assistant 232 and the liquid spraying section 20 .

In the electrospray method, the voltage application means 50 is generally set to a power supply voltage of about 10 kV to 30 kV. In contrast, the potential of the masking assistant 232 is preferably 1 kV to 5 kV, more preferably 2 kV to 4 kV.
If the potential of the masking assistant 232 is too high, the atomized liquid sprayed from the liquid spray unit 20 is charged with the same polarity as the masking assistant 232, and is therefore subjected to a repulsive force by the masking assistant 232. To prevent this, it is necessary to appropriately set the potential of the masking assistant 232, and the potential is set to a value that allows the atomized liquid to adhere to the masking assistant 232.

The workpiece 40 is connected to the negative electrode of the voltage application means 50, but the workpiece 40 may also be configured to be grounded.

FIG. 14 is a diagram showing the formation of a coating film with and without a constant voltage device 251 and an enlarged view of the coating film.
Figure 14(a) shows an enlarged view of the coating film formation and the coating film when a constant voltage device 251 is not connected to the masking auxiliary body 232, and Figure 14(b) shows an enlarged view of the coating film formation and the coating film when a constant voltage device 251 is connected to the masking auxiliary body 232.

14(a), the atomized liquid 287 sprayed from the liquid spray unit 20 is positively charged, and the masking assistant 232 and the workpiece 40 are negatively charged. The atomized liquid 287a sprayed at the center and its periphery passes straight through the hole 232a of the masking assistant 232, reaches the workpiece 40 and forms a coating film 285a.
Atomized liquid 287b sprayed outward is attracted by the edge of hole 232a and its traveling direction is bent further outward, reaching the workpiece 40 and forming coating film 285b. Atomized liquid 287c sprayed outward is attracted by the edge of hole 232a and adheres to the surface of masking assistant body 232 facing the workpiece 40, while atomized liquid 287d adheres to the liquid spraying section 20 side of masking assistant body 232 and does not reach the workpiece 40.
As shown in the enlarged view of the coating, the coating 285b is formed on the outside of the hole 232a of the masking assistant 232, and becomes thinner as it moves away from the hole 232a due to the dispersion of the atomized liquid 287b. Therefore, the coating becomes larger than the coating 285a on the outer edge of the hole 232a of the masking assistant 232 that is originally intended to be formed, and the outline becomes unclear.

In order to improve the quality of such a coating film 285, it is necessary to reduce the gap Ta between the workpiece 40 and the masking assistant 232 and reduce the outward movement of the atomized liquid 287b.
However, if the gap Ta is made smaller, in a configuration in which the masking auxiliary body 32 is positioned in a non-contact state with a gap between it and the workpiece 40, and it is possible to move the workpiece 40 relative to the liquid spray section 20 and the masking jig 230, restrictions will be placed on the relative movement of the workpiece 40 and the masking jig 230.

In this way, in order to ensure high quality of the coating film 285 and to enable relative movement between the workpiece 40 and the masking jig 230, the closest part of the masking aid 232 to the workpiece 40 is in a non-contact state with the workpiece 40, and the distance is set to 20 mm or less, preferably 10 mm or less, and more preferably 8 mm or less.

14B, a constant voltage device 251 is connected to the masking auxiliary body 232. The potential of the constant voltage device 251 is set to have the same polarity as that of the liquid spraying part 20 and to have a smaller potential difference with the workpiece 40 than with the liquid spraying part 20.
That is, although the liquid spraying part 20 and the masking assistant 232 are the same positive electrode, the potential of the masking assistant 232 is considerably lower than that of the liquid spraying part 20. Preferably, the potential of the liquid spraying part 20 is 10 kV or more and 30 kV or less, while the potential of the masking assistant 232 is 1 kV or more and 5 kV or less.
The workpiece 40 is connected to the negative electrode of the voltage application means 50 and has the same potential as the negative electrode. Furthermore, when the workpiece 40 is grounded, the potential relative to the ground is 0V.

Positively charged atomized liquid 287 is sprayed from liquid spray unit 20, moves toward workpiece 40, and reaches the vicinity of the masking assistant body. Then, the atomized liquid 287a that reaches hole 232a of masking assistant body 232 is not attracted to masking assistant body 232 of the same polarity, and since the potential of masking assistant body 232 is relatively close to that of atomized liquid 287, it is hardly subjected to a repulsive force, travels straight through hole 232a, and reaches workpiece 40.
The atomized liquid 287b that reaches the outside of the hole 232a of the masking assistant 232 adheres to the surface of the masking assistant 232 on the liquid spray section 20 side without being subjected to any repulsive force, since the potential of the masking assistant 232 is relatively close to that of the atomized liquid 287.
In this way, the potential of the masking assistant 232 is maintained at a potential that allows the atomized liquid atomized by the electrostatic spraying device 10 to be applied to the liquid spraying section 20 side of the masking assistant 232 .
Furthermore, the potential of the masking assistant 232 is maintained at a potential at which the atomized liquid does not adhere to the side of the masking assistant 232 facing the workpiece 40 .
The reason that an electric potential can be selected such that the atomized liquid is applied to the liquid spray portion 20 side of the masking auxiliary body 232 but not to the substrate 40 side is that the electric potential of the atomized liquid is relatively close to that of the atomized liquid 287, so the force it receives from the masking auxiliary body 232 is weak, and the atomized liquid has a high tendency to move in a straight line, so that a stronger force is required to pull the atomized liquid that has passed through the hole portion 232a of the masking auxiliary body 232 back in the opposite direction and apply it, and therefore the potential difference with the atomized liquid needs to be made larger.
By keeping the potential of the masking assistant 232 at such a potential, the path of the atomized liquid is not bent. Therefore, the atomized liquid 287a that has flowed toward the inside of the hole 232a of the masking assistant 232 reaches the workpiece 40 as is, and forms a coating film 285 that maintains the shape of the hole 232a. Meanwhile, the atomized liquid 287d that has flowed toward the outside of the hole 232a is applied to the surface of the masking assistant 232 on the liquid spraying section 20 side.
Therefore, by maintaining the potential of the masking assistant 232 at such a potential, it is possible to eliminate the atomized liquid corresponding to the atomized liquid 287b and the atomized liquid 287c in Figure 14 (a), thereby improving the quality of the coating film 285.

As a result, as shown in the enlarged view of the coating, the coating 285 formed on the workpiece 40 is only the coating 285a, which is equal to the hole 232a of the masking auxiliary body 232. The coating 285a is of uniform thickness, resulting in a coating 285 of very high quality.

Even when forming a high quality coating film 285 in this manner, the gap Tb between the workpiece 40 and the masking auxiliary body 232 can be made sufficiently wide.
For example, when the gap Ta is approximately 1 mm to 2 mm, the gap Tb can be set to approximately 10 mm, so that there is no hindrance to the relative movement of the workpiece 40 and the liquid spray section 20 and masking jig 230.

Since the masking auxiliary body 232 shown in Figure 12 has a planar shape, the closest part, which is the part that is closest to the workpiece 40, is the entire surface of the masking auxiliary body 232 that is closest to the workpiece 40, and the gaps Ta and Tb shown in Figure 14 correspond to this distance.
12 and 14, the masking auxiliary 232 is described as having a hole 232a, but the present invention is not limited thereto. In this embodiment, the masking auxiliary 232 is not limited to the presence or absence of a hole, and can be applied to masking auxiliary 232 of various shapes and configurations. The masking auxiliary 232 may be a masking that is a single plate without holes and forms a coating film by utilizing its outer shape, or may be a masking that is composed of multiple maskings and forms a coating film of the shape formed by the maskings, as shown in FIGS. 10 and 11. In this way, by connecting the constant voltage device 251 to the masking auxiliary 232 of various shapes and configurations and setting the potential of the masking auxiliary 232 to the potential described above, a coating film 285 of very high quality can be formed in the same way. Furthermore, even when forming such a high-quality coating film 285, the gap between the workpiece 40 and the masking auxiliary body 232 can be made sufficiently wide, so that there is no hindrance to the relative movement of the workpiece 40 and the liquid spray section 20 and masking jig 230.

FIG. 15 is a cross-sectional view showing a modified example of a masking jig 230 according to the third embodiment of the present invention.
16A and 16B are a front view and a cross-sectional view, respectively, showing a masking jig 230 according to a fourth embodiment of the present invention.
The masking jig 230 shown in Fig. 15 differs from the masking jig 230 shown in Fig. 12 in that the masking auxiliary body 232 has a truncated cone shape. Other than the shape of the masking auxiliary body 232, the masking jig 230 is similar to the configuration shown in Fig. 12, and the constant voltage device 251 connected to the masking auxiliary body 232 is also similar to the configuration shown in Fig. 12.

The masking jig 230 of the fourth embodiment shown in FIG. 16 is formed by attaching the masking jig 230 shown in FIG. 15 to the liquid nozzle 22 of the liquid spray unit 20 by a support member 240 and an attachment member 241 to form an integrated structure. The fourth embodiment shown in FIG. 16 will be described below.

Fourth Embodiment
The masking jig 230 of the fourth embodiment differs from that of the second embodiment shown in FIG. 8 in that a constant voltage device 251 is connected to a masking assistant body 232.
The masking assistant 232 is similar to the second embodiment in that it is made of a conductive material, a semiconductive material having a surface resistance of 10 ¹⁰ Ω or less, or an antistatic material.

15 and 16, the masking jig 230 has a masking auxiliary body 232 but does not have a masking main body. In this embodiment, the masking jig 230 may or may not have a masking main body.
When a masking body is provided, its arrangement, role, material, etc. are the same as those in the first, second and third embodiments.

The function of the constant voltage device 251 connected to the masking assistant body 232 is similar to that of the configuration shown in FIG.
That is, when the constant voltage device 251 is connected to the masking auxiliary body 232, the potential of the liquid spray section 20 is the highest, the masking auxiliary body 232 is the next highest, and the workpiece 40 is the lowest. The potential difference between the masking auxiliary body 232 and the workpiece 40 is the rated voltage of the constant voltage device 251. That is, when the workpiece 40 is taken as the reference potential, the masking auxiliary body 232 has a positive potential.

Therefore, when a constant voltage device 251 is connected to the masking auxiliary body 232, the potentials of the liquid spray section 20, the masking auxiliary body 232, and the workpiece 40 can be set to a predetermined relationship by selecting the power supply voltage of the voltage application means 50 and the rated voltage of the constant voltage device 251.
In this embodiment, it is preferable that the potential of the masking assistant 232 be set to the same polarity as that of the liquid spraying section 20 and that the potential difference between the masking assistant 232 and the workpiece 40 is smaller than the potential difference between the masking assistant 232 and the liquid spraying section 20 .
In addition, the potential of the masking assistant 232 is maintained at a potential that allows the atomized liquid atomized by the electrostatic spraying device 10 to be applied to the liquid spraying section 20 side of the masking assistant 232.
Furthermore, the potential of the masking assistant 232 is maintained at a potential at which the atomized liquid does not adhere to the side of the masking assistant 232 facing the workpiece 40 .

In the electrospray method, the voltage application means 50 is generally set to a power supply voltage of about 10 kV to 30 kV. In contrast, the potential of the masking assistant 232 is preferably 1 kV to 5 kV, more preferably 2 kV to 4 kV.
If the potential of the masking assistant 232 is too high, the atomized liquid sprayed from the liquid spray unit 20 is charged with the same polarity as the masking assistant 232, and is therefore subjected to a repulsive force by the masking assistant 232. To prevent this, it is necessary to set the potential of the masking assistant 232 appropriately.

The workpiece 40 is connected to the negative electrode of the voltage application means 50, but may also be configured to be grounded.

The masking auxiliary body 232 has a truncated cone shape, is hollow and made of a thin plate-shaped conductive material or an antistatic material with a surface resistance of 10 ¹⁰ Ω or less, and has a hole 232a on the side closer to the workpiece 40. The small diameter end 232c is on the side closer to the workpiece 40, and the large diameter end 232d is on the side closer to the liquid spraying section 20, and these are connected by a side surface 232e. In other words, the distance to the masking auxiliary body 232 in the direction perpendicular to the axis of the liquid nozzle 22 becomes the same or longer as it moves from the workpiece 40 toward the liquid spraying section 20. When the hole 232a is formed over the entire small diameter end 232c, it can also be considered that the area of the hole 232a becomes larger as it moves away from the workpiece 40 toward the liquid spraying section 20.

In the masking auxiliary body 232, the small diameter end portion 232c which surrounds or forms the edge of the hole portion 232a corresponds to the closest portion 232b which is the portion which is closest to the workpiece 40, but the small diameter end portion 232c is not in contact with the workpiece 40, and the distance therebetween is 20 mm or less, preferably 10 mm or less, and more preferably 8 mm or less.
The masking aid 232 defines an application area in the center and has a hole 232a through which the sprayed liquid passes, and the shape of the hole 232a can be freely selected depending on the pattern desired to be drawn on the substrate 40, and can be any shape, for example, circular, triangular, polygonal, etc.

16, the masking auxiliary body 232 is configured to have a truncated cone shape, but is not limited thereto, and may be, for example, a polygonal truncated pyramid shape, a cylindrical shape, or a flat or curved surface that does not form a hole. In the case of a cylindrical shape, the hole 232a has the same diameter even when it is away from the workpiece 40. Similarly, the inner peripheral length of the perpendicular cross section of the masking auxiliary body 132 with respect to the central axis of the hole 232a also remains the same length even when it is away from the workpiece 40.
In the embodiment shown in Figure 16, a support member 240 is connected to three points on the side 231e of the masking auxiliary body 231 near the large diameter end 231d, and its rear end is connected to an attachment member 241 and formed as one unit.

The mounting member 241 has a through hole with approximately the same diameter as the outer diameter of the liquid nozzle 22, and the liquid nozzle 22 is fitted into this through hole and fixed.
That is, the masking auxiliary body 232 is fixed to the liquid nozzle 22 via the support member 240 and the mounting member 241, whereby the masking jig 230 is attached to the liquid spraying section 20 to form an integrated structure.

In this way, by integrating the masking jig 230 and the liquid spray unit 20, the masking jig 230 and the liquid spray unit 20 can be moved together relative to the workpiece 40, and the coating film defined by the hole 232a of the masking auxiliary body 232 can be used as a reference unit to apply various shapes by combining these reference units. In other words, special coating operations such as drawing dots, lines, or pictures can be performed.

In addition, when the masking jig 230 is configured to be in contact with the workpiece 40 as in the conventional case, even if the workpiece 40 is one on which the masking jig 230 cannot be placed, precise coating work can be performed using the masking jig 230. For example, even if the workpiece 40 has an uneven surface or is a curved surface, the masking jig 230 of this embodiment can be appropriately positioned to perform coating work. If the workpiece 40 has uneven surfaces, the masking jig 230 and the liquid spray unit 20 can be moved three-dimensionally, including forward and backward, as a single unit to perform coating work.

Since the masking auxiliary body 232 is configured in a truncated cone shape, the atomized liquid within the same diameter range as the hole portion 232a reaches the hole portion 232a without being affected much by the masking auxiliary body 232 until it comes close to the hole portion 232a, and then passes directly through the hole portion 232a to the workpiece 40 and forms a coating film.
The side surface 232e of the masking auxiliary body 232 facing the workpiece 40 is inclined with respect to the central axis of the liquid nozzle 22 of the liquid spraying section 20, and further, in this embodiment, a constant voltage device 251 is connected to the masking auxiliary body 232, so that the potential difference of the masking auxiliary body 232 with the workpiece 40 is set to be smaller than the potential difference with the liquid spraying section 20.
Furthermore, since the masking auxiliary body 232 has the same polarity as the atomized liquid and is at a significantly lower potential than the atomized liquid, the atomized liquid passing near the inner edge of the hole 232a is hardly influenced by the masking auxiliary body 232 and travels almost in a straight line until it reaches the workpiece 40 and forms a coating film, thereby making it possible to form a coating film with high precision on the hole 232a.

In Figure 14 (a), the atomized liquid 287c passing just beside the inner peripheral edge of the hole 232a is attracted to the masking assistant body 232, changes its direction of travel by approximately 180°, and reaches the side of the masking assistant body 232 closer to the workpiece 40.
However, in the fourth embodiment shown in Fig. 16, the potential of the masking assistant body 232 has the same polarity as the atomized liquid, so the atomized liquid is not attracted to the masking assistant body 232. Therefore, even if the liquid passes through the inner periphery of the hole portion 232a, there is no liquid that behaves like the atomized liquid 287c in Fig. 14(a).
By doing this, it is possible to form a coating film of high quality, and it is also possible to reduce the amount of liquid adhering to the masking auxiliary body 232, thereby eliminating waste of liquid and significantly reducing the number of times the masking auxiliary body 132 needs to be cleaned.
In this way, in the fourth embodiment, a coating film of extremely high quality can be formed by the synergistic effect of configuring the masking auxiliary body 232 in a truncated cone shape or the like and connecting to the masking auxiliary body 232.

The masking aid 232 is not limited to the truncated cone shape shown in FIG. 16, but may be formed of two separate plate-like objects as shown in FIG. 10 and FIG. 11, and may be configured so that the distance between the two plate-like objects in the direction perpendicular to the axis of the liquid nozzle 22 is the same or longer as it moves away from the workpiece 40 in the axial direction of the liquid nozzle 22.

In this way, the action and effect obtained by connecting the constant voltage device 251 to the masking auxiliary body 232 are similar to those in the cases shown in FIGS.
In other words, the coating film formed on the substrate 40 is similar to the coating film 285a shown in Figure 14 (b), is formed equal to the hole portion 232a of the masking auxiliary body 232, the thickness of the coating film is uniform, and is a coating film of very high quality.

Furthermore, even when forming such a high quality coating film, the gap between the workpiece 40 and the masking auxiliary body 232 can be made sufficiently wide.
For example, the gap between the workpiece 40 and the closest part 232b of the masking auxiliary body 232 can be about 10 mm, so that there is no hindrance to moving the workpiece 40 relative to the liquid spray section 20 and the masking jig 230.

As explained above, this embodiment can provide a masking jig that can be used for special coating operations such as drawing dots, lines, or pictures, or for coating operations where it is difficult to place a masking jig on the workpiece, and can form a coating film of extremely high quality.

Although the present invention has been described above based on specific embodiments, the present invention is not limited to the above embodiments, and modifications and improvements may be made as appropriate.
For example, an additional opposite polarity portion or electrode may be provided near the liquid nozzle 22 of the liquid spray unit 20 to promote the liquid to be separated in an electrically charged state.
In addition, although the liquid spraying part 20 has been described as having a positive potential and the workpiece 40 as having a negative potential throughout the above explanation, this is not limited to this. The same effect can be obtained even if the liquid spraying part 20 has a negative potential and the workpiece 40 has a positive potential, and in this case, in the first and second embodiments, the masking auxiliary body 232 has the same potential as the workpiece 40, i.e., a positive potential, while in the third and fourth embodiments, the masking auxiliary body 232 has the same polarity as the liquid spraying part 20, i.e., a negative potential.
Furthermore, the masking auxiliary 32, 232 is not limited to a configuration in which the hole 32a, 232a is provided, and there is no limitation on the presence or absence of holes, and it can be applied to masking auxiliary 32, 232 of various shapes and configurations. The masking auxiliary 32, 232 may be a masking that is in the form of a single plate without holes and forms a coating film by utilizing its outer shape, or, as shown in Figures 10 and 11, a masking that is composed of multiple maskings and forms a coating film of the shape formed by these maskings, will have the same effect.

As such, the present invention is not limited to the specific embodiments, and appropriate modifications and improvements are also included within the technical scope of the present invention, which will be clear to those skilled in the art from the claims.

10 Electrostatic spray device 20 Liquid spray section 21 Body section 21a Liquid supply port 21b Liquid flow path 21c Hole section 21d Rear end opening 21e Female screw structure 22 Liquid nozzle 22a Tip outer periphery 22b Opening 23 Axle 23a Knob section 23b Electrical wiring connection section 23c Male screw structure 23d Tip surface 24 Seal member 30 Masking jig 31 Masking body 31a Opening 31b Outer periphery 32 Masking auxiliary body 32a Hole section 32b Closest section 34 Insulating back cover 34a Opening 35 Periphery 40 Heterogenous pole section (subject to be coated)
41 Coating portion 42 Non-coating portion 43 Boundary 50 Voltage application means 60 Earth means 80 Taylor cone 82 Jet portion 85 Coating film 87a, b, c, d Spray liquid 130 Masking jig 131 Masking body 131a Opening 131c Small diameter end 131d Large diameter end 131e Side 132 Masking auxiliary body 132a Hole 132b Closest portion 132c Small diameter end 132d Large diameter end 132e Side 140 Support member 141 Mounting member 230 Masking jig 232 Masking auxiliary body 232a Hole 232b Closest portion 232c Small diameter end 232d Large diameter end 232e Side 240 Support member 241 Mounting member 251 Constant voltage device 285 Coating film 287 Atomized liquid 287a, b, c, d Atomized liquid

Claims (5)

A masking tool for use in an electrostatic spraying device, which applies a voltage between a liquid spraying section and a different pole section that is a different pole to the liquid spraying section, generates an electrostatic force to cause the liquid to be separated from the liquid spraying section in an electrically charged state, and sprays the atomized liquid onto a workpiece that is the different pole section,
The masking device includes a masking body made of an insulating material and a masking assistant made of a conductive material or a semiconductive material,
the masking body is disposed so as not to apply the liquid to the object to be coated, and is in an electrically charged state so as to repel the liquid;
the masking assistant is disposed on the object to be coated so as to define a boundary between a non-coating portion to which the liquid is not applied and a coating portion to which the liquid is applied, and has the same potential as the object to be coated;
The masking body and the masking auxiliary body are arranged in a non-contact state with the object to be coated.
A masking jig characterized by: the masking auxiliary body has a distance to the masking auxiliary body that is the same or longer in a direction perpendicular to the axis of the liquid nozzle as the masking auxiliary body moves away from the application section in an axial direction of the liquid nozzle that sprays the liquid in the liquid spray section;
2. The masking jig according to claim 1 . At the edge of the masking auxiliary body on the side of the substrate, a closest portion which is a portion closest to the substrate is disposed within 10 mm of the substrate.
3. The masking jig according to claim 1 or 2 . The masking assistant is attached to the liquid spray unit.
The masking jig according to any one of claims 1 to 3 . The masking aid has a hole that defines the application portion,
The area of the hole is the same or increases with increasing distance from the application part.
The masking jig according to any one of claims 1 to 4 .