Electrostatic film forming device

Abstract

To provide an electrostatic film forming device which crushes lumps of powder having fallen from a hopper, and can uniformly attach the powder to an object.SOLUTION: An electrostatic film forming device includes: a screen 10; a rubbing member 12 having a powder rubbed surface 12a for rubbing powder to the screen 10; a power source DC for applying a voltage between the screen 10 and an object 1; a hopper 14 for supplying the powder; and a vibration sieve device 30 which is arranged below the hopper 14. The vibration sieve device 30 includes: a powder receiving part 33 which receives powder supplied from the hopper 14, and has a plurality of openings 35 capable of passing the powder therethrough; and a vibration generator 34 for vibrating the powder receiving part 33.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrostatic film forming device that adheres powder, such as edible powder or functional powder, to an object by utilizing electrostatic force. [Background technology]

[0002] Electrostatic screen printing apparatuses are used for various purposes such as printing on food products and manufacturing industrial products. The principle of this electrostatic printing will be described with reference to FIG. 27. As shown in FIG. 27, the electrostatic screen printing apparatus includes a conveyor 201 on which an object 200 is placed, a screen 202 having a mesh, a roll brush 203 on the screen 202, and a hopper 204 that supplies powder to the roll brush 203. The object 200 is moved by the conveyor 201 to a printing position below the screen 202.

[0003] The screen 202 is connected to the negative terminal of a power supply DC, and the conveyor 201 is connected to the positive terminal of the power supply DC and is also grounded. A high voltage is applied between the screen 202 and the conveyor 201 by the power supply DC, which creates an electrostatic field between the screen 202 and the object 200 on the conveyor 201.

[0004] The powder is supplied from a hopper 204 onto the rotating roll brush 203, and falls onto the screen 202. The powder on the screen 202 is rubbed into the mesh of the screen 202 by the rotating roll brush 203, and is pushed out through the mesh to the bottom of the screen 202. At this time, the powder is negatively charged due to friction with the rotating roll brush 203. Therefore, the powder is attracted to the grounded object 200 and adheres to the surface of the object 200, forming a film of uniform thickness on the object 200.

[0005] Because this type of electrostatic printing technology is capable of forming uniform powder films, it has recently begun to be used in the manufacture of a variety of industrial products, including fuel cells, all-solid-state batteries, secondary batteries, and cosmetics. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2002-347221 A Summary of the Invention [Problem to be solved by the invention]

[0007] The hopper 204 includes a hopper box 205 that stores powder, and a hopper brush 206 disposed in the hopper box 205. A plurality of through holes 207 that allow the powder to pass through are formed in the bottom of the hopper box 205. When the hopper brush 206 rotates, the powder in the hopper box 205 is pushed into the plurality of through holes 207. The powder does not immediately fall from the through holes 207, but is attracted to each other by the electrostatic force, van der Waals force, or liquid bridging force of the powder itself, forming a lump. When the lump becomes large enough, the lump of powder falls from the hopper 204 onto the roll brush 203 due to its own weight.

[0008] However, the powder lumps that fall under their own weight tend to be relatively large, which can cause the thickness of the powder film formed on the target object 200 to be non-uniform. As a result, this can reduce the product yield or cause product defects.

[0009] Therefore, the present invention provides an electrostatic film forming apparatus capable of crushing lumps of powder that have dropped from a hopper and allowing the powder to adhere uniformly to an object. [Means for solving the problem]

[0010] In one aspect, there is provided an electrostatic film formation apparatus that adheres powder onto an object by electrostatic force, the electrostatic film formation apparatus comprising: a screen; a rubbing member having a powder rubbing surface for rubbing powder into the screen; a power source for applying a voltage between the screen and the object; a hopper for supplying the powder; and a vibrating sieve device arranged below the hopper, the vibrating sieve device comprising a powder receiving section that receives the powder supplied from the hopper and has a plurality of openings through which the powder can pass, and a vibration generator that vibrates the powder receiving section.

[0011] In one aspect, the hopper has a powder outlet for passing the powder, and a total area of ​​the multiple openings of the powder receiving portion is greater than a total area of ​​the powder outlet. In one embodiment, the vibrating screen device is disposed above the scrubbing member. In one embodiment, the vibrating screen device is connected to the hopper via a vibration isolator. In one embodiment, the electrostatic deposition apparatus further includes a hopper moving device that moves the hopper and the vibrating screen device together in parallel with the screen. In one aspect, the electrostatic deposition apparatus further includes an auxiliary power supply that applies an auxiliary voltage to the bottom of the vibrating sieve device, and the polarity of the auxiliary voltage applied from the auxiliary power supply to the bottom of the vibrating sieve device is opposite to the polarity of the voltage applied from the power supply to the screen.

[0012] In one aspect, an electrostatic film formation device is provided that adheres powder onto an object by electrostatic force, the device comprising: a screen; a rubbing member having a powder rubbing surface for rubbing powder into the screen; a powder rubbing surface moving device that moves the powder rubbing surface relative to the screen; a power source for applying a voltage between the screen and the object; a hopper that supplies the powder to the powder rubbing surface of the rubbing member; and a contact member that contacts the powder rubbing surface, the contact member being a structure that does not allow the powder to pass through.

[0013] In one embodiment, the contact member has a plurality of protrusions that contact the powder rubbing surface. In one embodiment, the contact member is made of metal and is grounded. In one embodiment, the contact member is located above the screen and below the hopper. In one embodiment, the powder rubbing surface moving device is configured to move the rubbing member in a direction in which the powder rubbing surface comes into contact with the contact member and then with the screen. In one embodiment, the electrostatic film forming apparatus further includes a rubbing member moving device that separates the rubbing member from the contact member and moves the rubbing member on the screen. Effect of the Invention

[0014] The vibrating sieve device can pulverize the powder lumps that have fallen from the hopper by applying vibrations to them. The pulverized powder is then fed from the vibrating sieve device to a rubbing member or a screen. The rubbing member can rub the powder into the screen and attach the powder evenly to the object.

[0015] The contact member can crush the powder lumps that have fallen from the hopper by pressing them against the rubbing member. The multiple protrusions of the contact member can reliably crush the crushed powder and further distribute it on the powder rubbing surface of the rubbing member. Therefore, the rubbing member can rub the powder into the screen and evenly attach the powder to the target object. [Brief description of the drawings]

[0016] [Figure 1] 1 is a front view showing an embodiment of an electrostatic deposition apparatus. [Diagram 2] FIG. 2 is a side view of the electrostatic film forming apparatus shown in FIG. [Diagram 3] FIG. 13 is a diagram showing an example of a powder outlet. [Figure 4] FIG. 1 illustrates a top view of one embodiment of a vibrating screen device. [Diagram 5] 5 is a cross-sectional view taken along line AA in FIG. 4. [Figure 6] FIG. 11 is a side cross-sectional view showing another embodiment of a vibrating screen device. [Figure 7] FIG. 1 is a diagram showing an embodiment of an electrostatic deposition apparatus equipped with a hopper moving device. [Figure 8] FIG. 13 shows how a hopper and vibrating screen device are moved above the screen while feeding powder onto the screen. [Figure 9] 13 is a diagram showing how the rubbing member rubs the powder on the screen into the mesh of the screen. FIG. [Figure 10] FIG. 1 is a diagram showing an embodiment of an electrostatic film forming apparatus including a hopper moving device that moves a hopper, a vibrating screen device, and a rubbing member as a unit; [Figure 11] FIG. 13 is a diagram showing another embodiment of the electrostatic deposition apparatus. [Figure 12] FIG. 13 is a diagram showing still another embodiment of the electrostatic film forming apparatus. [Figure 13] FIG. 13 is a diagram showing still another embodiment of the electrostatic film forming apparatus. [Figure 14] FIG. 14 is a side view of the electrostatic film forming apparatus shown in FIG. [Figure 15] 1 illustrates an embodiment of a contact surface of a contact member. [Figure 16] 11A and 11B are diagrams illustrating an example of a plurality of protrusions of a contact member. [Figure 17] 13A and 13B are diagrams illustrating other examples of a plurality of protrusions of the contact member. [Figure 18] 13A and 13B are diagrams showing still another example of a plurality of protrusions of the contact member. [Figure 19] 13A and 13B are diagrams showing still another example of a plurality of protrusions of the contact member. [Figure 20] FIG. 13 is a side view showing another embodiment of the contact member. [Figure 21] FIG. 13 is a diagram showing still another embodiment of the electrostatic film forming apparatus. [Figure 22] 11A and 11B are diagrams illustrating a state in which the actuator moves the second divided body of the contact member. [Diagram 23]11A and 11B are diagrams illustrating how the rubbing-member moving device moves the rubbing member on the screen. [Figure 24] FIG. 1 is a diagram showing an embodiment of an electrostatic deposition apparatus including a vibrating sieve device and a contact member. [Diagram 25] FIG. 1 is a diagram showing an embodiment of an electrostatic deposition apparatus including a vibrating sieve device and a contact member. [Figure 26] FIG. 1 is a diagram showing an embodiment of an electrostatic deposition apparatus including a vibrating sieve device and a contact member. [Figure 27] FIG. 1 is a diagram showing a conventional example of an electrostatic film forming apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view showing one embodiment of an electrostatic film forming apparatus, and FIG. 2 is a side view of the electrostatic film forming apparatus shown in FIG. 1. The electrostatic film forming apparatus includes a screen 10, a rubbing member 12 for rubbing powder into the screen 10, a power source DC for applying a voltage between the screen 10 and the target 1, a hopper 14 for supplying powder, and a vibrating sieve device 30 arranged below the hopper 14. The screen 10 is arranged above the target 1. Examples of the powder include edible powder and functional powder. The target 1 is not particularly limited, and may be food, or industrial products such as fuel cells, all-solid-state batteries, secondary batteries, and cosmetics.

[0018] The hopper 14 is located above the vibrating sieve device 30, the rubbing member 12, and the screen 10. The vibrating sieve device 30 is disposed above the screen 10 and the rubbing member 12. As shown in Fig. 2, the bottom 33a of the powder receiving section 33 is made of a mesh having a plurality of openings 35 through which the powder can pass.

[0019] The rubbing member 12 is in contact with the screen 10. The rubbing member 12 has a powder rubbing surface 12a for rubbing the powder into the screen 10. In this embodiment, the rubbing member 12 is a cylindrical rubbing roller, but is not limited to a cylindrical rubbing roller as long as it can rub the powder into the screen 10. As an example of a material for the rubbing member 12, a soft urethane sponge is used because of its good ability to rub the powder into the screen 10. In particular, an open-cell urethane sponge is preferably used because of its good powder retention.

[0020] A conveyor 2 is disposed below the screen 10, which transports a number of objects 1 horizontally. The conveyor 2 moves the objects 1 sequentially to a position below the screen 10. A belt-type conveyor already installed in the factory can be used as the conveyor 2. The screen 10 is connected to the negative terminal of a power supply (voltage application device) DC, and the conveyor 2 is connected to the positive terminal of the power supply DC. The positive terminal of the power supply DC and the conveyor 2 are grounded. A high voltage is applied between the screen 10 and the conveyor 2 by the power supply DC, which creates an electrostatic field between the screen 10 and the objects 1 on the conveyor 2.

[0021] As shown in FIG. 2, the rubbing member 12 is connected to a rubbing roller rotating mechanism 19 as a powder rubbing surface moving device. The rubbing member 12 is rotated by the rubbing roller rotating mechanism 19 about its axis extending parallel to the screen 10, and the powder rubbing surface 12a of the rubbing member 12 is brought into sliding contact with the mesh 11 of the screen 10. The rubbing roller rotating mechanism 19 is composed of a motor and a torque transmission mechanism (e.g., a sprocket, a chain, etc.). Alternatively, the rubbing roller rotating mechanism 19 may include a motor directly connected to the rubbing member 12. In this embodiment, the rubbing roller rotating mechanism 19 constitutes a powder rubbing surface moving device that moves the powder rubbing surface 12a relatively to the screen 10.

[0022] The hopper 14 is disposed above the screen 10. The hopper 14 includes a hopper box 20 that stores powder therein, a hopper roller 22 disposed inside the hopper box 20, and a hopper roller rotation mechanism 24 that rotates the hopper roller 22. An example of a material for the hopper roller 22 is urethane sponge. The hopper roller rotation mechanism 24 is composed of a motor and a torque transmission mechanism (e.g., a sprocket, a chain, etc.). The hopper roller rotation mechanism 24 may be composed of a motor directly connected to the hopper roller 22.

[0023] As shown in FIG. 1, powder outlet 25 is formed in bottom 14A of hopper box 20. Powder outlet 25 is a plurality of through holes or slits. FIG. 3 is a diagram showing an example of powder outlet 25. In the example shown in FIG. 3, powder outlet 25 is composed of a plurality of through holes 25a for passing powder. In another example, powder outlet 25 may be one or a plurality of slits instead of the plurality of through holes 25a.

[0024] When the hopper roller rotation mechanism 24 rotates the hopper roller 22, the powder in the hopper box 20 is agitated by the hopper roller 22 and forced into the powder outlet 25 at the bottom 14A of the hopper box 20, and falls onto the vibrating sieve device 30. The powder further falls from the vibrating sieve device 30 onto the rubbing member 12. The amount of powder supplied to the rubbing member 12 can be adjusted by the rotation speed of the hopper roller 22.

[0025] The vibrating sieve device 30 includes a powder receiving section 33 that receives the powder supplied from the hopper 14, and a vibration generator 34 that vibrates the powder receiving section 33. The powder receiving section 33 has a plurality of openings 35 through which the powder can pass at its bottom 33a. The vibration generator 34 is fixed to a side wall of the powder receiving section 33. The vibration generator 34 is configured to vibrate itself, and the vibration of the vibration generator 34 vibrates the powder receiving section 33. The direction of the vibration is parallel to the bottom 33a of the powder receiving section 33 and the screen 10, as shown in FIG. 2. The specific configuration of the vibration generator 34 is not particularly limited as long as it can generate vibrations. For example, a gas pressure type vibration generator that operates with the pressure of compressed gas, or a motor type vibration generator that generates vibrations by the rotation of an electric motor is used.

[0026] 2, powder receiving portion 33 is supported by bracket 31 via vibration-proof material 39. Vibration-proof material 39 is made of a flexible material such as silicone. Vibration-proof material 39 is configured to be able to support powder receiving portion 33 while allowing powder receiving portion 33 to vibrate.

[0027] The powder supplied from the hopper 14 is received by the vibrating sieve device 30, and then falls from the vibrating sieve device 30 onto the rubbing member 12. The powder is carried to the screen 10 by the rotating rubbing member 12. The powder is rubbed into the mesh 11 of the screen 10 by the rotating rubbing member 12 and pushed out to the opposite side of the screen 10. At this time, the powder is negatively charged by friction with the rotating rubbing member 12. Therefore, the powder is attracted to the grounded object 1 and adheres to the surface of the object 1, forming a film of uniform thickness on the object 1. It is preferable to oscillate the rubbing member 12 in its axial direction by an oscillating mechanism (not shown) while rubbing the powder into the screen 10. Some types of powder are positively charged when rubbed into the mesh 11 of the screen 10 by the rubbing member 12. When using such powder, the screen 10 is connected to the positive pole of a power source DC, and the negative pole of the power source DC and the conveyor 2 are grounded.

[0028] Next, the vibrating sieve device 30 will be described in detail. FIG. 4 is a top view of one embodiment of the vibrating sieve device 30, and FIG. 5 is a cross-sectional view taken along line AA in FIG. 4. In this embodiment, the bottom 33a of the powder receiving section 33 is made of a mesh having a plurality of openings 35 through which the powder can pass. In another example, the bottom 33a of the powder receiving section 33 may be made of a punching metal having a plurality of openings 35 through which the powder can pass. The powder receiving section 33 has a recess 37 that opens upward, and the recess 37 is formed on the bottom 33a. The powder (including clumps of powder) that has fallen from the hopper 14 is received by the bottom 33a and temporarily stored in the recess 37.

[0029] The vibrating sieve device 30 applies vibrations to powder lumps to break them down. More specifically, the vibration generator 34 applies vibrations to the powder receiver 33, so that the powder lumps on the powder receiver 33 are broken down. The fine powder passes through a plurality of openings 35 and falls onto the rubbing member 12. The rubbing member 12 rubs the powder into the screen 10, allowing the powder to adhere uniformly to the object.

[0030] When the powder supplied from the hopper 14 accumulates on the powder receiving portion 33, the vibration of the vibration generator 34 is not easily transmitted to the upper layer of the powder on the powder receiving portion 33 due to the nature of the powder. As a result, the lumps present in the upper layer of the powder are not crushed, and the lumps remain in the powder on the powder receiving portion 33. Therefore, in this embodiment, the total area of ​​the multiple openings 35 of the powder receiving portion 33 is made larger than the total area of ​​the powder outlet 25 of the hopper 14. With this configuration, the powder receiving portion 33 does not become a rate-limiting factor for the supply of powder from the hopper 14 to the rubbing member 12, and the amount of powder on the powder receiving portion 33 does not increase cumulatively.

[0031] 6 is a side cross-sectional view showing another embodiment of the vibrating sieve device 30. As shown in FIG. 6, the vibrating sieve device 30 is connected to the hopper 14 via a plurality of vibration-proof materials 39. More specifically, the side wall of the powder receiving portion 33 is held to the side wall of the hopper box 20 via a plurality of vibration-proof materials 39. The vibration-proof materials 39 are sandwiched between the side wall of the powder receiving portion 33 and the side wall of the hopper box 20. The vibration-proof materials 39 are made of a flexible material such as silicone, and prevent the vibration of the vibrating sieve device 30 from being transmitted to the hopper 14.

[0032] When the vibrations of the vibrating sieve device 30 are transmitted to the hopper 14, the powder particles in the hopper box 20 may clump together due to the vibrations. The vibration-proof material 39 can prevent such clumping of the powder particles. The vibrating sieve device 30 is held to the hopper 14 by the vibration-proof material 39, and therefore can move together with the hopper 14.

[0033] FIG. 7 is a diagram showing an embodiment of an electrostatic film forming apparatus equipped with a hopper moving device 41. The configuration of this embodiment that is not particularly described is the same as the embodiment described with reference to FIG. 1 to FIG. 6, so the overlapping description will be omitted. As shown in FIG. 7, the electrostatic film forming apparatus is equipped with a hopper moving device 41 that moves the hopper 14 and the vibrating screen device 30 together in parallel with the screen 10. The specific configuration of the hopper moving device 41 is not particularly limited, but for example, a linear actuator equipped with a pulley and a belt can be used for the hopper moving device 41. In this embodiment, the vibrating screen device 30 is held by the hopper 14 via a vibration isolator 39 (see FIG. 6). Therefore, the hopper moving device 41 can move the hopper 14 and the vibrating screen device 30 together.

[0034] The electrostatic film forming apparatus of this embodiment further includes a rubbing member moving device 44 that moves the rubbing member 12 on the screen 10. The specific configuration of the rubbing member moving device 44 is not particularly limited, but for example, a linear actuator equipped with a pulley and a belt can be used for the rubbing member moving device 44. The hopper moving device 41 and the rubbing member moving device 44 can operate independently of each other.

[0035] In this embodiment, first, the powder is scattered on the screen 10 by the hopper 14 and the vibrating sieve device 30. Next, the powder on the screen 10 is rubbed into the mesh 11 of the screen 10 by the rubbing member 12. That is, as shown in FIG. 8, the hopper 14 and the vibrating sieve device 30 are moved above the screen 10 by the hopper moving device 41 while supplying the powder onto the screen 10. The rubbing member 12 is in a retreat position away from the mesh 11 of the screen 10. Thereafter, as shown in FIG. 9, the hopper 14 and the vibrating sieve device 30 are moved by the hopper moving device 41 to a retreat position away from the mesh 11 of the screen 10. Furthermore, the rubbing member 12 is moved over the screen 10 by the rubbing member moving device 44 while rotating, and rubs the powder on the screen 10 into the mesh 11 of the screen 10.

[0036] In this embodiment, the vibrating sieve device 30 can also pulverize lumps of powder by applying vibrations to the lumps. The fine powder falls from the vibrating sieve device 30 onto the screen 10. The rubbing member 12 rubs the powder into the screen 10, allowing the powder to adhere uniformly to the object.

[0037] Furthermore, in one embodiment, as shown in Fig. 10, the hopper moving device 41 may also be connected to the rubbing member 12, and the hopper moving device 41 may be configured to move the hopper 14, the vibrating sieve device 30, and the rubbing member 12 as a unit. In the embodiment shown in Fig. 10, the rubbing member 12 is connected to the hopper moving device 41 by a connecting member (e.g., a frame) not shown. In this embodiment, the rubbing member moving device 44 shown in Figs. 7 to 9 is not provided.

[0038] 10, the hopper 14, the vibrating sieve device 30, and the rubbing member 12 are moved above the screen 10 by a hopper moving device 41, while the hopper 14 and the vibrating sieve device 30 supply powder onto the rubbing member 12. Furthermore, the rubbing member 12 rubs the powder supplied to the rubbing member 12 into the meshes 11 of the screen 10 while rotating.

[0039] As described above, the vibrating sieve device 30 can pulverize the powder lumps supplied from the hopper 14 into fine powder. However, if the powder falling from the vibrating sieve device 30 is too fine, the powder becomes suspended particles floating in space and is difficult to fall under its own weight. Therefore, in one embodiment shown in FIG. 11, the electrostatic film forming device has an auxiliary power supply 45 that applies an auxiliary voltage to the bottom 33a of the vibrating sieve device 30. Since the rubbing member 12 is in contact with the screen 10 to which a negative voltage is applied, the rubbing member 12 is negatively charged. Therefore, an electrostatic field is formed between the bottom 33a of the vibrating sieve device 30 and the rubbing member 12. Other configurations of the embodiment shown in FIG. 11 that are not particularly described are the same as those of the embodiment shown in FIG. 1 to FIG. 5, so that the overlapping description will be omitted.

[0040] The bottom 33a of the vibrating sieve device 30 is made of a metal such as conductive stainless steel. The polarity of the auxiliary voltage applied to the bottom 33a of the vibrating sieve device 30 is opposite to the polarity of the voltage applied to the screen 10. In the embodiment shown in FIG. 11, the polarity of the voltage applied to the screen 10 is negative, so the polarity of the auxiliary voltage applied to the bottom 33a of the vibrating sieve device 30 is positive. When the polarity of the voltage applied to the screen 10 is positive, the polarity of the auxiliary voltage applied to the bottom 33a of the powder receiving section 33 is negative. One electrode of the auxiliary power supply 45 is electrically connected to the bottom 33a of the vibrating sieve device 30, and the other electrode of the auxiliary power supply 45 is grounded.

[0041] The powder on the bottom 33a of the vibrating sieve device 30 is positively charged by the auxiliary voltage applied by the auxiliary power supply 45. Then, the positively charged powder is carried to the rubbing member 12 by the electrostatic field formed between the bottom 33a of the powder receiving part 33 and the rubbing member 12. According to this embodiment, the electrostatic field formed between the bottom 33a of the powder receiving part 33 and the rubbing member 12 can prevent the fine powder pulverized by the vibrating sieve device 30 from floating in the air.

[0042] The embodiment shown in Fig. 12 is an example in which the auxiliary power supply 45 shown in Fig. 11 is applied to the embodiment described with reference to Fig. 7 to Fig. 9. In the embodiment shown in Fig. 12, the electrostatic film forming apparatus has an auxiliary power supply 45 that applies an auxiliary voltage to the bottom 33a of the vibrating sieve device 30, and forms an electrostatic field between the bottom 33a of the vibrating sieve device 30 and the screen 10. One electrode of the auxiliary power supply 45 is electrically connected to the bottom 33a of the vibrating sieve device 30, and the other electrode of the auxiliary power supply 45 is grounded.

[0043] The powder on the bottom 33a of the vibrating sieve device 30 is positively charged by the auxiliary voltage applied by the auxiliary power supply 45. Then, the positively charged powder is carried to the screen 10 by the electrostatic field formed between the bottom 33a of the powder receiving part 33 and the screen 10. According to this embodiment, the electrostatic field formed between the bottom 33a of the powder receiving part 33 and the screen 10 can prevent the fine powder pulverized by the vibrating sieve device 30 from floating in the air.

[0044] Although not shown, the auxiliary power supply 45 can also be applied to the embodiment described with reference to FIG.

[0045] Next, another embodiment of the electrostatic film forming apparatus will be described with reference to Figs. 13 to 20. The configuration of this embodiment that is not particularly described is the same as that of the embodiment described with reference to Figs. 1 to 3, so the overlapping description will be omitted. The electrostatic film forming apparatus of this embodiment does not include a vibrating sieve device 30, but instead includes a contact member 50 for crushing powder lumps. The contact member 50 of this embodiment is a contact plate. The contact member 50 is held by a holding member 51, and the relative position of the contact member 50 with respect to the rubbing member 12 is fixed. The contact member 50 is disposed between the hopper 14 and the screen 10. The contact member 50 is located above the screen 10 and below the hopper 14.

[0046] The contact member 50 of this embodiment has a flat contact surface 50a. The contact surface 50a of the contact member 50 is in contact with the powder rubbing surface 12a of the rubbing member 12. In the embodiment shown in FIG. 13, the powder rubbing surface 12a is a cylindrical outer circumferential surface of the rubbing member 12. Since the rubbing member 12 is made of an elastic material such as urethane sponge, the portion of the rubbing member 12 in contact with the contact member 50 is slightly deformed inward. The contact member 50 not only has the function of crushing the lumps of powder that have fallen from the hopper 14, but also has the function of pushing the crushed powder into the rubbing member 12 (holding the powder on the powder rubbing surface 12a).

[0047] Fig. 14 is a side view of the electrostatic film formation apparatus shown in Fig. 13. The width W of the contact member 50 is the same as the axial length L of the rubbing member 12. In one embodiment, the width W of the contact member 50 may be longer than the axial length L of the rubbing member 12. The contact member 50 having such dimensions can press the powder supplied from the hopper 14 against the powder rubbing surface 12a of the rubbing member 12.

[0048] 15 is a diagram showing one embodiment of the contact surface 50a of the contact member 50. In this embodiment, the multiple protrusions 52 of the contact member 50 are lattice-like linear protrusions. The multiple protrusions 52 constituting the lattice-like linear protrusions include linear protrusions extending perpendicular to the moving direction S of the powder-rubbing surface 12a.

[0049] The rubbing roller rotation mechanism 19 is a powder rubbing surface moving device that moves the powder rubbing surface 12a relative to the screen 10. The rubbing roller rotation mechanism 19 is configured to move the powder rubbing surface 12a in a direction in which the powder rubbing surface 12a contacts the contact member 50 and the screen 10 in that order. In this embodiment, the rubbing roller rotation mechanism 19 rotates the rubbing member 12 counterclockwise (see FIG. 13). Therefore, the powder lump that has fallen from the hopper 14 onto the powder rubbing surface 12a of the rubbing member 12 reaches the contact member 50 as the rubbing member 12 rotates. The contact member 50 presses the powder lump against the rubbing member 12 to pulverize the powder lump. Furthermore, the multiple protrusions 52 (see FIG. 15) of the contact member 50 can disperse the pulverized powder onto the powder rubbing surface 12a while pulverizing the powder lump. The pulverized powder is moved to the screen 10 as the rubbing member 12 rotates, and is rubbed into the screen 10 by the rubbing member 12 .

[0050] The contact member 50 has a structure that does not allow the powder to pass through. More specifically, the contact member 50 does not have an opening that allows the powder to pass through. Therefore, the contact member 50 can press the powder supplied from the hopper 14 against the powder rubbing surface 12a of the rubbing member 12, and the powder can be held by the rubbing member 12.

[0051] The contact member 50 is made of metal, and is grounded as shown in Fig. 13 and Fig. 14. Therefore, the contact member 50 also functions as a static eliminator that eliminates static electricity from the powder. Depending on the type of powder, the contact member 50 may be made of a non-metal such as resin.

[0052] In the embodiment shown in FIG. 13, the contact member 50 is disposed on only one side of the scrubbing member 12, however, multiple contact members 50 may be disposed on both sides of the scrubbing member 12.

[0053] The shape of the multiple protrusions 52 of the contact member 50 is not limited to the example shown in FIG. 15, as long as it can crush the powder lumps and disperse the crushed powder on the powder-rubbing surface 12a. For example, as shown in FIG. 16, the multiple protrusions 52 may be wavy filament protrusions extending along the moving direction S of the powder-rubbing surface 12a. Alternatively, as shown in FIG. 17, the multiple protrusions 52 may be linear filament protrusions extending perpendicular to the moving direction S of the powder-rubbing surface 12a. Alternatively, as shown in FIG. 18 and FIG. 19, the multiple protrusions 52 may be round or polygonal protrusions distributed over the entire contact surface 50a.

[0054] Fig. 20 is a side view showing another embodiment of the contact member 50. In Fig. 20, the contact surface 50a of the contact member 50 is curved along the powder rubbing surface 12a of the rubbing member 12. According to the embodiment shown in Fig. 20, the contact area between the contact member 50 and the powder rubbing surface 12a is increased, so that powder lumps can be crushed more reliably.

[0055] Fig. 21 is a diagram showing yet another embodiment of the electrostatic film forming apparatus. The configuration of this embodiment that is not particularly described is the same as the embodiment described with reference to Figs. 13 to 20, so the overlapping description will be omitted. The electrostatic film forming apparatus further includes a rubbing member moving device 44 that separates the rubbing member 12 from the contact member 50 and moves the rubbing member 12 on the screen 10. The specific configuration of the rubbing member moving device 44 is not particularly limited, but for example, a linear actuator equipped with a pulley and a belt can be used for the rubbing member moving device 44.

[0056] The hopper 14 and the contact member 50 are disposed outside the screen 10, and the relative positions of the hopper 14 and the contact member 50 with respect to the screen 10 are fixed. That is, the rubbing member moving device 44 moves the rubbing member 12, while the hopper 14 and the contact member 50 do not move. The contact surface 50a of the contact member 50 has a curved shape that contacts both sides and the bottom of the powder rubbing surface 12a of the rubbing member 12. That is, the contact surface 50a of the contact member 50 contacts at least the lower half of the powder rubbing surface 12a.

[0057] The contact member 50 is composed of a first divided body 53A and a second divided body 53B. The first divided body 53A is held by a holding member 51, and the second divided body 53B is rotatably connected to the first divided body 53A by a hinge 54 arranged at the bottom of the contact member 50. When the contact member 50 is viewed from the axial direction of the rubbing member 12, the first divided body 53A constitutes the left half of the contact member 50, and the second divided body 53B constitutes the right half of the contact member 50. The first divided body 53A and the second divided body 53B are connected to each other at the bottom of the contact member 50, so that the powder does not fall from the bottom of the contact member 50.

[0058] An actuator 55 is connected to the second divided body 53B. This actuator 55 is configured to move the second divided body 53B relative to the first divided body 53A. More specifically, as shown in FIG. 22, when the actuator 55 moves the second divided body 53B in a direction away from the first divided body 53A, the second divided body 53B rotates about the hinge 54, and the inner surface of the second divided body 53B moves away from the powder rubbing surface 12a of the rubbing member 12. Furthermore, when the actuator 55 moves the second divided body 53B toward the first divided body 53A, the second divided body 53B rotates in the opposite direction about the hinge 54, and as shown in FIG. 21, the inner surface of the second divided body 53B comes into contact with the powder rubbing surface 12a of the rubbing member 12.

[0059] Next, the operation of the electrostatic film forming apparatus of this embodiment will be described. First, as shown in FIG. 21, in a state where both the first divided body 53A and the second divided body 53B of the contact member 50 are in contact with the powder rubbing surface 12a of the rubbing member 12, the rubbing member 12 is rotated and powder (including powder lumps) is supplied from the hopper 14 onto the rubbing member 12. The contact member 50 presses the powder lumps against the rubbing member 12 to pulverize the powder lumps. Furthermore, the contact member 50 presses the pulverized powder against the powder rubbing surface 12a of the rotating rubbing member 12 to hold the powder on the rubbing member 12. The rotation direction and rotation speed of the rubbing member 12 are not particularly limited. Such an operation of holding the powder on the rubbing member 12 is performed for a predetermined time. When the rubbing member 12 is rotated forward and backward, the powder can be held uniformly on the rubbing member 12.

[0060] Thereafter, the supply of powder from the hopper 14 is stopped. Furthermore, as shown in Fig. 22, the actuator 55 moves the second divided body 53B in a direction separating it from the first divided body 53A, and separates the second divided body 53B from the rubbing member 12. Then, as shown in Fig. 23, the rubbing member moving device 44 separates the rubbing member 12 from the first divided body 53A of the contact member 50, and moves the rubbing member 12 on the screen 10. The rubbing member 12 holding the powder can rub the powder into the mesh 11 of the screen 10 while rotating.

[0061] When rubbing of the powder into the screen 10 is completed, the rubbing member moving device 44 returns the rubbing member 12 to the position shown in FIG. 22, and further, the actuator 55 returns the second divided body 53B to the position shown in FIG.

[0062] According to this embodiment, the rubbing member moving device 44 moves only the rubbing member 12, and does not move the hopper 14 or the contact member 50, so that the rubbing member moving device 44 can be made compact. Furthermore, a hopper moving device for moving the hopper 14 is not required. As a result, the entire film forming apparatus can be made compact.

[0063] The embodiment described with reference to Figures 1 to 12 may be appropriately combined with the embodiment described with reference to Figures 13 to 23. For example, as shown in Figures 24 to 26, a contact member 50 may be disposed below the vibrating screen device 30.

[0064] The above-described embodiments have been described for the purpose of enabling a person having ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments are naturally possible for a person skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope according to the technical idea defined by the claims. [Explanation of symbols]

[0065] 1. Object 2 Conveyor 10 Screens 11 Mesh 12 Rubbing material 12a Powder-rubbed surface DC power supply 14 Hopper 14A bottom 19 Rub-in roller rotation mechanism (powder rub-in surface moving device) 20 Hopper Box 22 Hopper Roller 24 Hopper roller rotation mechanism 25 Powder outlet 25a Multiple holes 30 Vibrating Screen Device 31 Bracket 33 Powder receiving part 33a bottom 34 Vibration Generator 35 Aperture 37 Depression 39 Vibration isolation material 41 Hopper moving device 44 Rub-in material moving device 45 Auxiliary power supply 50 Contact member 50a contact surface 51 Retaining member 52 Protrusion 53A 1st division body 53B Second division 54 Hinge 55 Actuator

Claims

1. An electrostatic film forming apparatus that deposits powder onto an object by electrostatic force, A screen and a rubbing member having a powder rubbing surface for rubbing powder into the screen; a power source for applying a voltage between the screen and the object; A hopper for supplying the powder; A vibrating screen device is provided below the hopper, The vibrating screen device comprises: a powder receiving portion that receives the powder supplied from the hopper and has a plurality of openings through which the powder can pass; An electrostatic deposition apparatus comprising: a vibration generator that vibrates the powder receiving portion.

2. the hopper has a powder outlet for passing the powder therethrough; The electrostatic deposition apparatus according to claim 1 , wherein a total area of ​​the plurality of openings of the powder receiving portion is larger than a total area of ​​the powder outlet.

3. The electrostatic deposition apparatus according to claim 1 , wherein the vibrating sieve device is disposed above the scrubbing member.

4. The electrostatic deposition apparatus according to claim 1 , wherein the vibrating sieve device is connected to the hopper via a vibration isolator.

5. The electrostatic deposition apparatus according to claim 4 , further comprising a hopper moving device for moving the hopper and the vibrating screen device together in parallel with the screen.

6. Further comprising an auxiliary power supply for applying an auxiliary voltage to the bottom of the vibrating screen device; 2. The electrostatic deposition apparatus of claim 1, wherein the polarity of the auxiliary voltage applied from the auxiliary power supply to the bottom of the vibrating screen apparatus is opposite to the polarity of the voltage applied from the power supply to the screen.

7. An electrostatic film forming apparatus that deposits powder onto an object by electrostatic force, A screen and a rubbing member having a powder rubbing surface for rubbing powder into the screen; a powder rubbing surface moving device that moves the powder rubbing surface relative to the screen; a power source for applying a voltage between the screen and the object; a hopper for supplying the powder to the powder rubbing surface of the rubbing member; A contact member is provided for contacting the powder rubbed surface, The contact member is a structure that does not allow the powder to pass through.

8. The electrostatic film forming apparatus according to claim 7 , wherein the contact member has a plurality of protrusions that contact the powder rubbing surface.

9. The electrostatic deposition apparatus according to claim 7 , wherein the contact member is made of metal and is grounded.

10. The electrostatic deposition apparatus according to claim 7 , wherein the contact member is located above the screen and below the hopper.

11. 8. The electrostatic film forming apparatus according to claim 7, wherein the powder rubbing surface moving device is configured to move the rubbing member in a direction in which the powder rubbing surface comes into contact with the contact member and then with the screen.

12. 8. The electrostatic film forming apparatus according to claim 7, further comprising a rubbing member moving device that moves the rubbing member on the screen by separating the rubbing member from the contact member.

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