Static elimination device and ion balance control method

Abstract

To properly control both of the long-term ionic balance and the short-term ionic balance.SOLUTION: A current Idl flowing between an earth E and a static eliminator via a ground electrode Te is detected and feedback control is executed to a negative polarity high voltage power supply 92 such that the current Idl becomes a target current. A front wire net 115 that functions as a detection electrode different from the ground electrode Te is arranged at a position which a positive ion and a negative ion generated by an electrode needle Np and an electrode needle Nm reach. A current Idh generated by the positive ion and the negative ion reaching the front wire net 115 is detected, and the feedback control is executed to the negative polarity high voltage power supply 92 such that the current Idh becomes the target current Ith.SELECTED DRAWING: Figure 11A

Description

Technical Field

[0001] This invention relates to a technique for controlling the ion balance of ions emitted from a static eliminator to an object for static elimination of the object.

Background Art

[0002] Patent Document 1 discloses a static eliminator that generates corona discharge by applying positive and negative high voltages to positive and negative electrode needles respectively, thereby generating positive ions and negative ions. In order to reliably eliminate static electricity from an object using such a static eliminator, it is important to balance the generation amounts of positive ions and negative ions equally. Therefore, this static eliminator includes a detection resistor that detects the current flowing between the static eliminator and the ground, and performs feedback control on the positive and negative high voltages applied to the positive and negative electrode needles respectively based on the voltage generated in this detection resistor. Thereby, the difference between the generation amount of positive ions and the generation amount of negative ions can be suppressed, and an appropriate ion balance can be realized.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, mainly due to the large capacitance of the ground, the feedback control based on the current between the static eliminator and the ground has low responsiveness. Therefore, although an appropriate ion balance can be realized in the long term, the ion balance may become unstable in the short term.

[0005] This invention has been made in view of the above-mentioned problems, and aims to provide a technology that can appropriately control both long-term and short-term ion balance. [Means for solving the problem]

[0006] A static elimination device according to a first aspect of the present invention is a static elimination device that eliminates static electricity from an object by releasing ions to the object, and comprises: an ion generating unit that generates positive ions by generating corona discharge in response to the application of a positive polarity high voltage and generates negative ions by generating corona discharge in response to the application of a negative polarity high voltage; a high voltage application unit that applies a positive polarity high voltage and a negative polarity high voltage to the ion generating unit; a grounding electrode short-circuited to earth; a first detection circuit that detects a first ion current flowing between earth and the static elimination device via the grounding electrode; a detection electrode different from the grounding electrode, positioned at a location to which the positive and negative ions generated by the ion generating unit reach; a second detection circuit that detects a second ion current generated by the positive and negative ions that have reached the detection electrode; and a feedback control unit that performs feedback control on the high voltage application unit so that the first ion current detected by the first detection circuit becomes a first target value and so that the second ion current detected by the second detection circuit becomes a second target value.

[0007] An ion balance control method according to a first aspect of the present invention is an ion balance control method for controlling the ion balance of ions emitted from a static elimination device to an object in order to eliminate static electricity from the object, comprising the steps of: applying a positive polarity high voltage and a negative polarity high voltage from a high voltage application unit to an ion generating unit that generates positive ions by generating corona discharge in response to the application of a positive polarity high voltage and generates negative ions by generating corona discharge in response to the application of a negative polarity high voltage; detecting a first ion current flowing between the earth and the static elimination device via a grounding electrode short-circuited to earth; detecting a second ion current generated by positive ions and negative ions that have reached a detection electrode different from the grounding electrode, which is positioned at the location where the positive ions and negative ions generated by the ion generating unit reach; and performing feedback control on the high voltage application unit so that the first ion current becomes a first target value, and performing feedback control on the high voltage application unit so that the second ion current becomes a second target value.

[0008] According to the present invention (static elimination device and ion balance control method) configured as described above, an ion generating unit that generates positive and negative ions and a high-voltage application unit that applies positive and negative high voltages to the ion generating unit are provided. When the high-voltage application unit applies a positive high voltage to the ion generating unit, the ion generating unit generates positive ions, and when the high-voltage application unit applies a negative high voltage to the ion generating unit, the ion generating unit generates negative ions. Furthermore, a first ion current flowing between the earth and the static elimination device via a grounding electrode is detected, and feedback control is performed on the high-voltage application unit so that the first ion current reaches a first target value. This feedback control based on the first ion current allows for appropriate control of the long-term ion balance. In addition, a detection electrode different from the grounding electrode is placed at the position where the positive and negative ions generated by the ion generating unit reach. A second ion current generated by the positive and negative ions that reach this detection electrode is detected, and feedback control is performed on the high-voltage application unit so that the second ion current reaches a second target value. This feedback control based on the second ion current allows for appropriate control of the short-term ion balance. In this way, it becomes possible to appropriately control both long-term and short-term ion balance.

[0009] A static elimination device according to a second aspect of the present invention is a static elimination device that eliminates static electricity from an object by releasing ions to the object, and comprises: an ion generating unit that generates positive ions by generating corona discharge in response to the application of a positive polarity high voltage and generates negative ions by generating corona discharge in response to the application of a negative polarity high voltage; a high voltage application unit that applies a positive polarity high voltage and a negative polarity high voltage to the ion generating unit; a first detection circuit that detects a first ion current corresponding to the ratio of positive ions and negative ions generated by the ion generating unit that reaches a predetermined area outside the main body of the static elimination device; a detection electrode positioned at a location to which the positive ions and negative ions generated by the ion generating unit reach; a second detection circuit that detects a second ion current generated by the positive ions and negative ions that reach the detection electrode; and a feedback control unit that performs feedback control on the high voltage application unit so that the first ion current detected by the first detection circuit becomes a first target value and so that the second ion current detected by the second detection circuit becomes a second target value.

[0010] According to the present invention (static elimination device) configured as described above, an ion generating unit that generates positive and negative ions and a high-voltage application unit that applies positive and negative high voltages to the ion generating unit are provided. When the high-voltage application unit applies a positive high voltage to the ion generating unit, the ion generating unit generates positive ions, and when the high-voltage application unit applies a negative high voltage to the ion generating unit, the ion generating unit generates negative ions. Furthermore, a first ion current corresponding to the ratio of positive and negative ions generated by the ion generating unit that reaches a predetermined area outside the main body of the static elimination device is detected, and feedback control is performed on the high-voltage application unit so that the first ion current reaches a first target value. This feedback control based on the first ion current allows for appropriate control of the long-term ion balance. In addition, a detection electrode is placed at the position where the positive and negative ions generated by the ion generating unit reach. A second ion current generated by the positive and negative ions that reach this detection electrode is detected, and feedback control is performed on the high-voltage application unit so that the second ion current reaches a second target value. This feedback control based on the second ion current allows for appropriate control of the short-term ion balance. Thus, it is possible to appropriately control both the long-term and short-term ion balance. [Effects of the Invention]

[0011] As described above, the present invention makes it possible to appropriately control both long-term and short-term ion balance. [Brief explanation of the drawing]

[0012] [Figure 1] A front perspective view showing the external appearance of an example of a static elimination device according to the present invention. [Figure 2] A rear perspective view showing the external appearance of an example of a static elimination device in Figure 1. [Figure 3] Figure 1 shows a disassembled and assembled perspective view of an example of a static elimination device. [Figure 4]Rear view showing the inside of the static eliminator of FIG. 1. [Figure 5A] Rear view showing an example of the negative electrode unit. [Figure 5B] Rear view showing an example of the positive electrode unit. [Figure 6A] Rear perspective view showing the mode of fixing the negative electrode unit to the fixing base. [Figure 6B] Rear perspective view showing the mode of fixing the positive electrode unit to the fixing base. [Figure 6C] Rear perspective view showing the mode of fixing the negative electrode unit and the positive electrode unit to the fixing base. [Figure 6D] Enlarged perspective view showing an enlarged mode of fixing the negative electrode unit and the positive electrode unit to the fixing base. [Figure 7A] Perspective view showing a configuration for applying a voltage to the negative electrode unit. [Figure 7B] Perspective view showing a configuration for applying a voltage to the positive electrode unit. [Figure 8A] Rear view showing the configuration of the cleaning unit. [Figure 8B] Perspective view showing the configuration of the cleaning unit. [Figure 9] Block diagram briefly showing the configuration of the controller which is the electrical system of the static eliminator of FIG. 1. [Figure 10] Flowchart showing an example of the operation executed by the controller of FIG. 9. [Figure 11A] Block diagram showing the details of the electrode unit controller. [Figure 11B] Flowchart showing an example of the voltage control executed in the operation of FIG. 10. [Figure 12] Perspective view schematically showing a modified example of the negative electrode unit and the positive electrode unit. [Figure 13] Diagram schematically showing two systems for performing long-term and short-term feedback. [Figure 14] Perspective view showing an example of the ion balance sensor.

MODE FOR CARRYING OUT THE INVENTION

[0013] Figure 1 is a front perspective view showing the external appearance of an example of a static elimination device according to the present invention, Figure 2 is a rear perspective view showing the external appearance of an example of the static elimination device of Figure 1, Figure 3 is an exploded and assembled perspective view of an example of the static elimination device of Figure 1, and Figure 4 is a rear view showing the internal structure of the static elimination device of Figure 1. In this specification, the horizontal direction X, the horizontal direction Y perpendicular to the X direction, and the vertical direction Z will be appropriately indicated in the explanation. Furthermore, one side of the X direction will be appropriately referred to as the front side Xf, and the other side as the rear side Xb.

[0014] The static elimination device 1 comprises a front cover 11, a housing 2, a fan unit 3, a fixed base 4, a negative electrode unit 5, a positive electrode unit 6, a cleaning unit 7, and a rear cover 12. The housing 2 is broadly divided into an upper portion 2U and a lower portion 2L located below the upper portion 2U. A storage chamber 201 is provided in the upper portion 2U of the housing 2, and an electrical component storage section 202 is provided in the lower portion 2L of the housing 2. The storage chamber 201 has a rectangular shape when viewed from the X direction and opens in the X direction. The fan unit 3, fixed base 4, negative electrode unit 5, positive electrode unit 6, and cleaning unit 7 are arranged in the X direction and housed in the storage chamber 201. The electrical component storage section 202 houses the electrical system of the static elimination device 1. The front cover 11 is attached to the housing 2 from the front Xf, facing the storage chamber 201, and the rear cover 12 is attached to the housing 2 from the rear Xb, facing the storage chamber 201.

[0015] The housing 2 has a front frame 21 and a rear frame 25 provided on the rear side Xb of the front frame 21. The front frame 21 and the rear frame 25 are arranged in the X direction and attached to each other. The front frame 21 and the rear frame 25 are made of an antistatic resin and are conductive. The antistatic resin can be made by kneading an antistatic agent into the resin or by applying an antistatic agent to the surface of the resin. The antistatic resin in this embodiment is a resin that has a resistance value such that when the housing 2 is constructed, the charge generated on the surface of the housing 2 flows to the ground G in a relatively short time, for example, a few seconds. 9 Ω~10 12 Experimental results have shown that by using a resin in the Ω range, the charge generated on the surface of the housing 2 flows to the ground G in a few seconds. Furthermore, it is sufficient that the majority of the outer surface of the housing 2 is made of antistatic resin. In this embodiment, the display unit 23 is not made of antistatic resin, but the effect of a part of the housing 2 becoming charged is small.

[0016] The front frame 21 has a main frame 22 and a display unit 23 provided on the front side Xf of the main frame 22. The main frame 22 and the display unit 23 are arranged in the X direction and mounted to each other. The main frame 22 opens in the X direction. The display unit 23 is provided in the opening of the main frame 22 in its lower portion 2L and is positioned to be visible from the front side Xf. In other words, the upper portion 2U of the opening of the main frame 22 constitutes part of the storage compartment 201. Also, the lower portion 2L of the main frame 22 constitutes part of the electrical equipment storage compartment 202.

[0017] The rear frame 25 opens in the X direction. The opening in the upper portion 2U of the rear frame 25 constitutes part of the storage compartment 201. The lower portion 2L of the rear frame 25 constitutes part of the electrical equipment storage section 202.

[0018] The front cover 11 has a cover frame 111 made of antistatic resin, which is attached to the front frame 21 of the housing 2 from the front Xf at its upper portion 2U. This cover frame 111 covers the storage compartment 201 from the front Xf. The cover frame 111 also has a mesh portion 112 with multiple slits, which faces the storage compartment 201 from the front Xf. The front frame 21 is also fitted with a front wire mesh 115 (metal mesh) which is circular when viewed from the X direction. The front wire mesh 115 faces the storage compartment 201 from the front Xf and faces the mesh portion 112 from the rear Xb. These mesh portions 112 and the front wire mesh 115 allow air to pass through in the X direction. In this embodiment, the cover frame 111 has a mesh portion 112 with multiple slits, but it is sufficient if the shape can guide the airflow generated by the fan 33 (described later) to a desired area. Furthermore, although the front cover 11 is attached to the housing 2, it is also possible that the front cover 11 selected from multiple front covers 11 with different cover frame shapes is attached to the housing 2. With this configuration, the user can attach the front cover 11 selected according to the usage environment of the static eliminator 1 to the housing 2. For example, if the distance between the static eliminator 1 and the object to be eliminated is small, a front cover 11 suitable for guiding airflow nearby can be attached, and if the distance between the static eliminator 1 and the object to be eliminated is large, a front cover 11 suitable for guiding airflow to a distant location can be attached. In addition, in a configuration in which the front cover 11 is replaceable, it is also possible that parameters related to the operation of the static eliminator 1 are set according to the type of front cover 11 attached to the housing 2.

[0019] The rear cover 12 has a cover frame 121 made of antistatic resin, which is attached to the rear frame 25 of the housing 2 from the rear Xb at its upper portion 2U. The cover frame 121 has a circular opening 122 when viewed from the X direction, which faces the storage compartment 201 from the rear Xb. Furthermore, the rear cover 12 has a circular rear wire mesh 125 (metal mesh) when viewed from the X direction. The rear wire mesh 125 is fitted into the opening 122 and attached to the cover frame 121, facing the storage compartment 201 from the rear Xb. This rear wire mesh 125 allows air to pass through in the X direction. The rear wire mesh 125 is also short-circuited to ground G (Figure 9). Note that the manner in which the rear wire mesh 125 and ground G are electrically connected is not limited to a short circuit; they may also be connected via a resistor.

[0020] The fan unit 3 is located within the storage chamber 201 of the housing 2 and is positioned at the rear Xb of the front wire mesh 115 of the front cover 11. The fan unit 3 has a rectangular support frame 31 when viewed from the X direction, and the support frame 31 is located within the storage chamber 201 and attached to the housing 2. The support frame 31 has a circular ventilation opening 32 that opens in the X direction when viewed from the X direction. The ventilation opening 32 faces the front wire mesh 115 of the front cover 11 from the rear Xb. Furthermore, the fan unit 3 has a circular fan 33 when viewed from the X direction. The fan 33 has a rotating shaft 331 provided parallel to the X direction and a plurality of blades 332 provided around the rotating shaft 331. The fan 33 is also located within the ventilation opening 32 of the support frame 31 and faces the front wire mesh 115 of the front cover 11 from the rear Xb. The fan 33 is supported by a support frame 31 so as to be rotatable around a center of rotation parallel to the X direction, and by rotating around this center of rotation, it generates airflow (in other words, a breeze) in a blowing direction Dw from the rear Xb to the front Xf in the X direction.

[0021] The fixed base 4 is positioned in the storage chamber 201 of the housing 2 and is located at the rear Xb of the fan unit 3. The fixed base 4 has a fixed frame 41 which is rectangular when viewed from the X direction, and the fixed frame 41 is located inside the storage chamber 201 and attached to the housing 2. The fixed frame 41 has a ventilation opening 42 that opens in the X direction. This ventilation opening 42 has a rectangle with its four corners cut out in an arc shape when viewed from the X direction. The fixed base 4 also has fixing parts 43, 44, 45, and 46 provided at the four corners of the fixed frame 41. These fixing parts 43, 44, 45, and 46 are located outside the four corners of the ventilation opening 42. Furthermore, as will be described later, the fixed base 4 is provided with an I-shaped portion that supports the cleaning unit 7 relative to the fixed frame 41.

[0022] The negative electrode unit 5 is placed in the storage chamber 201 of the housing 2 and fixed to the fixing frame 41 of the fixing base 4 from the rear Xb. The negative electrode unit 5 has the configuration shown in Figure 5A. Here, Figure 5A is a rear view showing an example of the negative electrode unit. In Figure 5A, a virtual circle Cv (shown by a dashed line) with a circle centered at the center point Pc is shown when viewed from the X direction, and the circumferential direction Dc with the center point Pc is shown.

[0023] As shown in Figure 5A, the negative electrode unit 5 has a first unit frame 51 provided along a virtual circle C. In other words, the first unit frame 51 has an arc shape along the virtual circle C. Furthermore, the negative electrode unit 5 has a plurality (4) of electrode needles Nm arranged at a constant arrangement pitch (90 degrees) in the circumferential direction Dc along the virtual circle Cv. These plurality of electrode needles Nm are arranged along the inner wall 511 of the first unit frame 51 and protrude inward from this inner wall 511 (in other words, toward the center point Pc of the virtual circle Cv). The first unit frame 51 contains cables (wirings) electrically connected to each electrode needle Nm, and a voltage is applied to each electrode needle Nm via these cables.

[0024] Furthermore, the negative electrode unit 5 has a plurality (4) of fixing parts 53, 54, 55, 56 arranged at a constant arrangement pitch (90 degrees) in the circumferential direction Dc. In this example, the number of electrode needles Nm is equal to the number of fixing parts 53, 54, 55, 56. These plurality of fixing parts 53, 54, 55, 56 are arranged along the outer wall 512 of the first unit frame 51 and protrude outward from this outer wall 512 (in other words, on the opposite side of the center point Pc of the virtual circle Cv). In the circumferential direction Dc, the phase of the arrangement of the plurality of fixing parts 53, 54, 55, 56 is out of sync with the phase of the arrangement of the plurality of electrode needles Nm. That is, each fixing part 53, 54, 55, 56 is positioned offset in the circumferential direction Dc relative to the electrode needles Nm. Each of these fixing parts 53, 54, 55, and 56 is fastened to the fixing parts 43, 44, 45, and 46 of the fixing base 4 by screws S.

[0025] The airflow generated by the fan 33 of the fan unit 3 described above passes through the flow path Fw enclosed by the first unit frame 51 of the negative electrode unit 5 in the direction of airflow Dw. In other words, the first unit frame 51 of the negative electrode unit 5 has a curved shape (arc shape) that surrounds the flow path Fw through which the airflow generated by the fan 33 passes.

[0026] As shown in Figure 3, the positive electrode unit 6 is placed in the storage chamber 201 of the housing 2 and fixed to the fixing frame 41 of the fixing base 4 from the rear Xb. This positive electrode unit 6 has the configuration shown in Figure 5B. Here, Figure 5B is a rear view showing an example of the positive electrode unit. In Figure 5B, as in Figure 5A, a virtual circle Cv and the circumferential direction Dc are shown.

[0027] As shown in Figure 5B, the positive electrode unit 6 has a second unit frame 61 provided along a virtual circle C. In other words, the second unit frame 61 has an arc shape along the virtual circle C. Furthermore, the positive electrode unit 6 has a plurality (4) of electrode needles Np arranged at a constant arrangement pitch (90 degrees) in the circumferential direction Dc along the virtual circle Cv. These plurality of electrode needles Np are arranged along the inner wall 611 of the second unit frame 61 and protrude inward from this inner wall 611 (in other words, toward the center point Pc of the virtual circle Cv). The second unit frame 61 contains cables (wirings) electrically connected to each electrode needle Np, and a voltage is applied to each electrode needle Np via these cables.

[0028] Furthermore, the positive electrode unit 6 has a plurality (4) of fixing parts 63, 64, 65, 66 arranged at a constant arrangement pitch (90 degrees) in the circumferential direction Dc. In this example, the number of electrode needles Np is equal to the number of fixing parts 63, 64, 65, 66. These plurality of fixing parts 63, 64, 65, 66 are arranged along the outer wall 612 of the second unit frame 61 and protrude outward from this outer wall 612 (in other words, on the opposite side of the center point Pc of the virtual circle Cv). In the circumferential direction Dc, the phase of the arrangement of the plurality of fixing parts 63, 64, 65, 66 is out of sync with the phase of the arrangement of the plurality of electrode needles Np. That is, each fixing part 63, 64, 65, 66 is positioned offset in the circumferential direction Dc relative to the electrode needles Np. Each of these fixing parts 63, 64, 65, and 66 is fastened to the fixing parts 43, 44, 45, and 46 of the fixing base 4 by screws S.

[0029] The airflow generated by the fan 33 of the fan unit 3 described above passes through the flow path Fw enclosed by the second unit frame 61 of the positive electrode unit 6 in the direction of airflow Dw. In other words, the second unit frame 61 of the positive electrode unit 6 has a curved shape (arc shape) that surrounds the flow path Fw through which the airflow generated by the fan 33 passes.

[0030] The negative electrode unit 5 and the positive electrode unit 6 are arranged in the X direction within the storage chamber 201, with the positive electrode unit 6 positioned behind the negative electrode unit 5 at Xb. The negative electrode unit 5 and the positive electrode unit 6 are fixed to the fixing base 4 such that the first unit frame 51 of the negative electrode unit 5 and the second unit frame 61 of the positive electrode unit 6 overlap when viewed from the X direction. The fixing base 4 can be any member that fixes the negative electrode unit 5 and the positive electrode unit 6 in a desired arrangement, and the fixing base 4 may be composed of a single member or multiple members. Alternatively, other members, such as members constituting the housing 2, may also serve as the fixing base 4.

[0031] Figure 6A is a rear perspective view showing how the negative electrode unit is fixed to the fixed base, Figure 6B is a rear perspective view showing how the positive electrode unit is fixed to the fixed base, Figure 6C is a rear perspective view showing how the negative electrode unit and the positive electrode unit are fixed to the fixed base, and Figure 6D is an enlarged perspective view showing an enlarged view of how the negative electrode unit and the positive electrode unit are fixed to the fixed base.

[0032] The fixing portion 43 has a protruding plate 431 that protrudes outward from the first and second unit frames 51 and 61 when viewed from the X direction. When viewed from the rear, this protruding plate 431 protrudes to the upper left of the first and second unit frames 51 and 61. Furthermore, the fixing portion 43 has a fastening portion 432 that protrudes from the protruding plate 431 to the rear Xb in the X direction, and a fastening portion 433 that protrudes from the protruding plate 431 to the rear Xb in the X direction. In the fastening portion 432, a screw hole 432h extending in the X direction opens to the rear Xb, and in the fastening portion 433, a screw hole 433h extending in the X direction opens to the rear Xb. Screws S are screwed into these screw holes 432h and 433h. In the circumferential direction Dc, the fastening portions 432 and 433 are offset from each other, and the fastening portion 432 is located on one side of the fastening portion 433 (clockwise side when viewed from the rear).

[0033] The fixing portion 44 has a protruding plate 441 that protrudes outward from the first and second unit frames 51 and 61 when viewed from the X direction. When viewed from the rear, this protruding plate 441 protrudes to the lower left from the first and second unit frames 51 and 61. Furthermore, the fixing portion 44 has a fastening portion 442 that protrudes from the protruding plate 441 to the rear Xb in the X direction, and a fastening portion 443 that protrudes from the protruding plate 441 to the rear Xb in the X direction. In the fastening portion 442, a screw hole 442h extending in the X direction opens to the rear Xb, and in the fastening portion 443, a screw hole 443h extending in the X direction opens to the rear Xb. Screws S are screwed into these screw holes 442h and 443h. In the circumferential direction Dc, the fastening portion 442 and the fastening portion 443 are offset from each other, and the fastening portion 442 is located on one side of the fastening portion 443 (clockwise side when viewed from the rear).

[0034] The fixing portion 45 has a protruding plate 451 that protrudes outward from the first and second unit frames 51 and 61 when viewed from the X direction. When viewed from the rear, this protruding plate 451 protrudes to the lower right of the first and second unit frames 51 and 61. Furthermore, the fixing portion 45 has a fastening portion 452 that protrudes from the protruding plate 451 to the rear Xb in the X direction, and a fastening portion 453 that protrudes from the protruding plate 441 to the rear Xb in the X direction. In the fastening portion 452, a screw hole 452h extending in the X direction opens to the rear Xb, and in the fastening portion 453, a screw hole 453h extending in the X direction opens to the rear Xb. Screws S are screwed into these screw holes 452h and 453h. In the circumferential direction Dc, the fastening portion 452 and the fastening portion 453 are offset from each other, and the fastening portion 452 is located on one side of the fastening portion 453 (clockwise side when viewed from the rear).

[0035] The fixing portion 46 has a protruding plate 461 that protrudes outward from the first and second unit frames 51 and 61 when viewed from the X direction. When viewed from the rear, this protruding plate 461 protrudes to the upper right of the first and second unit frames 51 and 61. Furthermore, the fixing portion 46 has a fastening portion 462 that protrudes from the protruding plate 461 to the rear Xb in the X direction, and a fastening portion 463 that protrudes from the protruding plate 441 to the rear Xb in the X direction. In the fastening portion 462, a screw hole 462h extending in the X direction opens to the rear Xb, and in the fastening portion 463, a screw hole 463h extending in the X direction opens to the rear Xb. Screws S are screwed into these screw holes 462h and 463h. In the circumferential direction Dc, the fastening portion 462 and the fastening portion 463 are offset from each other, and the fastening portion 462 is located on one side of the fastening portion 463 (clockwise side when viewed from the rear).

[0036] Each of the fixing portions 53, 54, 55, and 56 of the negative electrode unit 5 is fastened to the fastening portions 432, 442, 452, and 462 of the fixing base 4 by screws S. Specifically, the fixing portion 53 has an insertion hole that extends in the X direction. Then, with the insertion hole of the adjacent fixing portion 53 and the screw hole 432h of the fastening portion 432 facing each other in the X direction from the rear Xb side of the fastening portion 432, the screw S inserted into the insertion hole of the fixing portion 53 is screwed into the screw hole 432h of the fastening portion 432. In this way, the fixing portion 53 is fastened to the fastening portion 432. The fixing portions 54, 55, and 56 are fastened in the same manner.

[0037] Each of the fixing portions 63, 64, 65, and 66 of the positive electrode unit 6 is fastened to the fastening portions 433, 443, 453, and 463 of the fixing base 4 by screws S. Specifically, the fixing portion 63 has an insertion hole extending in the X direction. Then, with the insertion hole of the adjacent fixing portion 63 and the screw hole 433h of the fastening portion 433 facing each other in the X direction from the rear Xb side of the fastening portion 433, the screw S inserted into the insertion hole of the fixing portion 63 is screwed into the screw hole 433h of the fastening portion 433. In this way, the fixing portion 63 is fastened to the fastening portion 433. Similarly, the fixing portions 64, 65, and 66 are fastened in the same manner.

[0038] Incidentally, fastening parts 433, 443, 453, and 463 have the same length as fastening parts 432, 442, 452, and 462. On the other hand, fastening parts 433, 443, 453, and 463 are longer than fastening parts 432, 442, 452, and 462. Therefore, the positive electrode unit 6 fastened to fastening parts 433, 443, 453, and 463 is located behind Xb of the negative electrode unit 5 fastened to fastening parts 432, 442, 452, and 462. In particular, the lengths of fastening parts 433, 443, 453, and 463 and fastening parts 432, 442, 452, and 462 are set so that there is a gap between the negative electrode unit 5 and the positive electrode unit 6 in the X direction.

[0039] Furthermore, the number of electrode needles Nm in the negative electrode unit 5 is equal to the number of electrode needles Np in the positive electrode unit 6 (4 needles), and the arrangement pitch of the electrode needles Nm in the negative electrode unit 5 is equal to the arrangement pitch of the electrode needles Np in the positive electrode unit 6 (90 degrees). On the other hand, as shown in Figure 4, for example, the phase of the arrangement of multiple electrode needles Nm in the negative electrode unit 5 and the phase of the arrangement of multiple electrode needles Np in the positive electrode unit 6 are shifted by 45 degrees. Therefore, when viewed from the X direction, the electrode needles Np and Nm are arranged alternately at a half-pitch (45 degrees), which is half of the above arrangement pitch. These electrode needles Np and Nm are arranged in the circumferential direction Dc so as to surround the airflow path Fw of the air generated by the fan 33 in the direction of airflow Dw, and the tips of the electrode needles Np and Nm each protrude into the airflow path Fw.

[0040] Figure 7A is a perspective view showing a configuration for applying voltage to the negative electrode unit. The static eliminator 1 has a harness Hm that extends from the electrical system housed in the electrical system storage section 202 to the fixing section 55 of the negative electrode unit 5, with electrode terminals exposed at the tip of the harness Hm. Also, on the front side Xf of the fixing section 55, the electrode terminals of the cable electrically connected to the electrode needle Nm are exposed. The fixing section 55 is fastened to the fastening section 452 with the electrode terminals of the harness Hm sandwiched between the fastening section 452 and the electrode terminals of the fixing section 55 of the negative electrode unit 5. As a result, the electrode terminals of the harness Hm and the electrode terminals of the cable of the negative electrode unit 5 make electrical contact, and the voltage supplied from the electrical system via the harness Hm is applied to the electrode needle Nm of the negative electrode unit 5.

[0041] Figure 7B is a perspective view showing a configuration for applying voltage to the positive electrode unit. The static eliminator 1 has a harness Hp that extends from the electrical system housed in the electrical system housing 202 to the fixing part 64 of the positive electrode unit 6, with electrode terminals exposed at the tip of the harness Hp. Also, on the side of the front Xf of the fixing part 64, the electrode terminals of the cable electrically connected to the electrode needle Np are exposed. The fixing part 64 is fastened to the fastening part 443 with the electrode terminals of the harness Hp sandwiched between the fastening part 443 and the electrode terminals of the fixing part 64 of the positive electrode unit 6. As a result, the electrode terminals of the harness Hp and the electrode terminals of the cable of the positive electrode unit 6 make electrical contact, and the voltage supplied from the electrical system via the harness Hp is applied to the electrode needle Np of the positive electrode unit 6.

[0042] Figure 8A is a rear view showing the configuration of the cleaning unit, and Figure 8B is a perspective view showing the configuration of the cleaning unit. The cleaning unit 7 includes cleaning brushes 71m and 71p, a motor 72, a rotating plate 73 driven by the motor 72, and a brush supporter 74 that supports the cleaning brushes 71m and 71p relative to the rotating plate 73.

[0043] The motor 72 is housed in a cylindrical portion of the fixed base 4 centered on an axis parallel to the X direction. The rotating plate 73 has a disc shape centered on the same axis. The motor 72 and the rotating plate 73 are positioned in the center of a virtual circle Cv when viewed from the X direction, and a gap CL is provided between the inner walls 511 and 611 of the first and second unit frames 51 and 61 respectively, extending from the outer circumference of the motor 72 and the rotating plate 73. This gap CL faces the multiple blades 332 of the fan 33, and the air generated by the fan 33 passes through the gap CL in the flow path Fw. The motor 72 has a rotation axis parallel to the X direction passing through its center point Pc, and the rotating plate 73 is mounted coaxially with the motor 72. The rotating plate 73 rotates in the circumferential direction Dc around the rotation axis of the motor 72 when driven by the motor 72. In this example, the motor 72 is a stepping motor. However, the type of motor 72 is not limited to this example.

[0044] The brush supporter 74 has a mounting portion 741 attached to the back of the rotating plate 73 and a screw 742 for fastening the mounting portion 741 to the back of the rotating plate 73. The tip of the mounting portion 741 protrudes to the outside of the rotating plate 73, and the brush supporter 74 has an extension portion 743 extending from the tip of the rotating plate 73 to the front Xf in the X direction, and two support portions 744m and 744p protruding radially outward from the extension portion 743 with a center point Pc. Each of the support portions 744m and 744p extends radially outward from the extension portion 743 of the rotating plate 73. The support portions 744m and 744p are arranged in the X direction, and the support portion 744p is located to the rear Xb of the support portion 744m. Furthermore, the brush supporter 74 has brush holders 745m and 745p attached to the tips of the support sections 744m and 744p, respectively. The brush holders 745m and 745p are arranged in the X direction, with brush holder 745p located on the rear side Xb of brush holder 745m.

[0045] The cleaning brush 71m is held by the brush holder 745m, and the cleaning brush 71p is held by the brush holder 745p. The cleaning brushes 71m and 71p are provided corresponding to the electrode needles Nm and Np, respectively, and extend radially from the center point Pc. The cleaning brushes 71m and 71p are arranged in the X direction, with the cleaning brush 71p located behind the cleaning brush 71m at Xb. The cleaning brush 71m faces the inner wall 511 of the first unit frame 51, and the cleaning brush 71p faces the inner wall 611 of the second unit frame 61. In this configuration, the cleaning brushes 71m and 71p move in the circumferential direction Dc by the driving force of the motor 72. The cleaning unit 7 then cleans the electrode needles Nm and Np by driving the cleaning brushes 71m and 71p with the motor 72 as follows.

[0046] In other words, multiple cleaning positions Lm are provided arranged in the circumferential direction Dc, and each of the multiple cleaning positions Lm corresponds to one of the multiple electrode needles Nm. The cleaning brush 71m comes into contact with one electrode needle Nm by being positioned at one cleaning position Lm that corresponds to one electrode needle Nm to be cleaned. In particular, the motor 72 slightly reciprocates the cleaning brush 71m that is in contact with one electrode needle Nm at one cleaning position Lm in the circumferential direction Dc, thereby allowing the tip of the cleaning brush 71m to scrub off dirt adhering to the one electrode needle Nm.

[0047] Similarly, multiple cleaning positions Lp are provided arranged in the circumferential direction Dc, and each of the multiple cleaning positions Lp corresponds to one of the multiple electrode needles Np. The cleaning brush 71p comes into contact with one of the electrode needles Np to be cleaned by positioning itself at one cleaning position Lp that corresponds to that electrode needle Np. In particular, the motor 72 slightly reciprocates the cleaning brush 71p that is in contact with one electrode needle Np at one cleaning position Lp in the circumferential direction Dc, thereby allowing the tip of the cleaning brush 71p to scrub off dirt adhering to the electrode needle Np.

[0048] Furthermore, the cleaning unit 7 has a brush cleaner 75 for cleaning the cleaning brushes 71m and 71p. The brush cleaner 75 has a storage box 751 for storing the cleaning brushes 71m and 71p. The storage box 751 is open in the circumferential direction Dc (in other words, the Y direction), and the cleaning brushes 71m and 71p can be moved in or out of the storage box 751 by the motor 72 moving them in the circumferential direction Dc. Incidentally, Figures 8A and 8B show the state in which the cleaning brushes 71m and 71p are out of the storage box 751, and Figure 4 shows the state in which the cleaning brushes 71m and 71p are inside the storage box 751.

[0049] The brush cleaner 75 removes dirt from the cleaning brushes 71m and 71p by sliding contact members provided inside the storage box 751. Specifically, sliding contact members are provided inside the storage box 751, corresponding to each opening on both sides of the storage box 751 in the circumferential direction Dc. The tips of the cleaning brushes 71m and 71p, which move in the circumferential direction Dc by the driving force of the motor 72, slide against the sliding contact members of the brush cleaner 75. As a result, the dirt attached to the cleaning brushes 71m and 71p is rubbed off by the sliding contact members of the brush cleaner 75, and the cleaning of the cleaning brushes 71m and 71p is performed. This cleaning is performed both when the cleaning brushes 71m and 71p enter the storage box 751 and when they exit the storage box 751.

[0050] The cleaning unit 7 is supported by the I-shaped portion of the fixed base 4 described above. Specifically, the motor 72 is supported by the fixed base 4 at the center of the I-shaped portion. The brush cleaner 75 is attached to the flat plate-shaped portion at the bottom of the fixed base 4.

[0051] Figure 9 is a simplified block diagram showing the configuration of the controller, which is the electrical system of the static elimination device shown in Figure 1. The static elimination device 1 includes a controller 8 housed in an electrical housing 202. The controller 8 includes a fan unit controller 81 that controls the fan unit 3, a cleaning unit controller 83 that controls the cleaning unit 7, and an electrode unit controller 9 that controls the negative electrode unit 5 and the positive electrode unit 6.

[0052] The fan unit controller 81 rotates the fan 33 of the fan unit 3, generating airflow in the direction of airflow Dw. This airflow flows into the housing 2 from the rear Xb via the rear wire mesh 125. Furthermore, after passing through the flow path Fw within the housing 2, this airflow flows out from the housing 2 to the front Xf via the front wire mesh 115 and mesh section 112. The airflow thus flowing out of the housing 2 reaches the object to be statically removed.

[0053] The cleaning unit controller 83 controls the rotational position of the motor 72 of the cleaning unit 7, thereby causing the cleaning brushes 71m and 71p to clean the electrode needles Nm and Np. In other words, when cleaning one electrode needle Nm out of several electrode needles Nm, the cleaning unit controller 83 controls the rotational position of the motor 72 to move the cleaning brush 71m to a cleaning position Lm opposite to the electrode needle Nm, and then moves the cleaning brush 71m back and forth slightly in the circumferential direction Dc (cleaning operation). Furthermore, by sequentially changing the electrode needle Nm to be cleaned among several electrode needles Nm and performing the cleaning operation, all of the electrode needles Nm can be cleaned. Similarly, when cleaning one electrode needle Np out of several electrode needles Np, the cleaning unit controller 83 controls the rotational position of the motor 72 to move the cleaning brush 71p to a cleaning position Lp opposite to the electrode needle Np, and then moves the cleaning brush 71p back and forth slightly in the circumferential direction Dc (cleaning operation). Furthermore, by sequentially changing the electrode needle Np to be cleaned among multiple electrode needles Np while performing the cleaning operation, all of the multiple electrode needles Np can be cleaned.

[0054] As described above, the electrode unit controller 9 is connected to the negative electrode unit 5 by harness Hm and to the positive electrode unit 6 by harness Hp. This electrode unit controller 9 controls the voltage applied to the electrode needle Nm of the negative electrode unit 5 via harness Hm and the voltage applied to the electrode needle Np of the positive electrode unit 6 via harness Hp, thereby generating a corona discharge between the tip of electrode needle Nm and the tip of electrode needle Np. This corona discharge generates negative ions around the tip of electrode needle Nm and positive ions around the tip of electrode needle Np. Furthermore, the rear wire mesh 125, the positive electrode unit 6, and the negative electrode unit 5 are arranged in order in the airflow direction Dw, and the rear wire mesh 125 is connected to ground G. Therefore, a corona discharge occurs between electrode needle Np and the rear wire mesh 125, generating positive ions around electrode needle Np. Similarly, a corona discharge occurs between electrode needle Nm and the rear wire mesh 125, generating negative ions around electrode needle Nm.

[0055] As described above, the electrode needles Nm and Np protrude into the flow path Fw, and the air generated by the fan 33 passes over the tips of the respective electrode needles Nm and Np. Therefore, the negative ions generated around the tip of electrode needle Nm and the positive ions generated around the tip of electrode needle Np are carried forward to the front Xf by the air passing through the flow path Fw in the direction of airflow Dw. The fan 33 that generates the airflow is located in front of the positive electrode unit 6 and the negative electrode unit 5, in other words, downstream of the direction of airflow Dw. Consequently, the negative and positive ions are stirred by the fan 33 and then flow out of the housing 2 to the front Xf via the front wire mesh 115 and the mesh section 112.

[0056] Figure 10 is a flowchart showing an example of an operation performed by the controller in Figure 9. In step S101, the cleaning unit controller 83 starts cleaning the electrode needles Nm and Np. As shown in Figure 8A, in the static elimination device 1, the electrode needles Nm and Np are arranged alternately in a clockwise direction in the circumferential direction Dc, resulting in a total of 8 electrode needles Nm and Np. In this case, the cleaning operation is performed on the 8 electrode needles Nm and Np in a clockwise direction, starting from the one closest to the storage box 751. More specifically, for each individual electrode needle Nm and Np, the cleaning brushes 71m and 71p are moved back and forth to pass over that electrode needle Nm and Np, and then the cleaning brushes 71m and 71p are moved to clean the next electrode needle Nm and Np. In this embodiment, the cleaning brushes 71m and 71p are moved so that the cleaning operation is performed for each individual electrode needle Nm and Np, but the method of movement is not limited to this. For example, the configuration may be such that all electrode needles Nm and Np are cleaned by moving the cleaning brushes 71m and 71p in one direction. Alternatively, the cleaning operation on the electrode needles Nm and Np may be performed in a counterclockwise direction, starting with those closest to the storage box 751.

[0057] In other words, the cleaning unit controller 83 controls the rotational position of the motor 72 to move the cleaning brushes 71m and 71p from the brush cleaner 75 to the cleaning position Lm facing the first electrode needle Nm, and performs a cleaning operation on the electrode needle Nm. At this time, the cleaning brushes 71m and 71p moving from the storage box 751 to the cleaning position Lm are slid against the sliding contact members of the brush cleaner 75, and cleaning of the cleaning brushes 71m and 71p is performed. Furthermore, once the cleaning operation on the last electrode needle Np is completed, the cleaning unit controller 83 controls the rotational position of the motor 72 to move the cleaning brushes 71m and 71p from the cleaning position Lp facing the last electrode needle Np to the storage box 751. At this time, the cleaning brushes 71m and 71p moving from the cleaning position Lp to the storage box 751 are slid against the sliding contact members of the brush cleaner 75, and cleaning of the cleaning brushes 71m and 71p is performed. Incidentally, the cleaning unit controller 83 slows down the speed of the cleaning brushes 71m and 71p when taking them out of the storage box 751 compared to the speed of the cleaning brushes 71m and 71p when putting them back into the storage box 751.

[0058] In step S102, the fan unit controller 81 starts rotating the fan 33 to generate airflow in the blowing direction Dw. In step S103, the electrode unit controller 9 starts applying voltage to the electrode needle Nm of the negative electrode unit 5 and to the electrode needle Np of the positive electrode unit 6. As a result, a DC negative voltage Vm lower than the ground G voltage is applied to the electrode needle Nm, and a DC positive voltage Vp higher than the ground G voltage is applied to the electrode needle Np. The rear wire mesh 125 is also connected to ground G. Therefore, a potential difference Vm is generated between the electrode needle Nm and the rear wire mesh 125, a potential difference Vp is generated between the electrode needle Nm and the rear wire mesh 125, and a potential difference Vpm (=Vp-Vm) is generated between the electrode needle Np and the electrode needle Nm. Then, negative ions and positive ions are generated by the corona discharge caused by the potential differences Vm, Vp, and Vpm, respectively. The negative and positive ions generated in this way are carried by the wind in the direction of the airflow Dw and released from the static elimination device 1 to the front Xf (static elimination operation). During the static elimination operation, the cleaning unit controller 83 controls the rotation position of the motor 72 to position the cleaning brushes 71m and 71p inside the storage box 751.

[0059] In step S104, feedback control is performed to control the ion balance in the long term and short term. Details of this voltage control will be described later with reference to Figures 11A and 11B. In step S105, following step S104, when the electrode unit controller 9 stops applying voltage to the electrode needles Nm and Np, in step S106, the fan unit controller 81 stops the fan 33, ending the airflow by the fan 33.

[0060] Figure 11A is a block diagram showing the details of the electrode unit controller. The electrode unit controller 9 includes a CPU (Central Processing Unit) 91, a negative polarity high-voltage power supply 92 that generates a voltage Vm applied to the electrode needle Nm, and a positive polarity high-voltage power supply 93 that generates a voltage Vp applied to the electrode needle Np. The CPU 91 performs digital signal processing to control the negative polarity high-voltage power supply 92 and the positive polarity high-voltage power supply 93. This CPU 91 includes a high-voltage control unit 911 that controls the voltage Vp (high voltage) applied to the electrode needle Np, and a first balance control unit 912 that controls the balance (ion balance) between negative ions and positive ions generated by the application of voltages Vp and Vm to the electrode needles Np and Nm. Specifically, the CPU 91 configures the high-voltage control unit 911 and the first balance control unit 912 by executing a predetermined program.

[0061] The negative polarity high-voltage power supply 92 is a transformer having a primary circuit 921 and a secondary circuit 922. A voltage signal Vim is input to the primary circuit 921, and the secondary circuit 922 is connected to each electrode needle Nm of the negative electrode unit 5 by a harness Hm. Then, a voltage Vm corresponding to the voltage signal Vim input to the primary circuit 921 is applied from the secondary circuit 922 to each electrode needle Nm via the harness Hm.

[0062] The positive polarity high-voltage power supply 93 is a transformer having a primary circuit 931 and a secondary circuit 932. A voltage signal Vip is input to the primary circuit 931, and the secondary circuit 932 is connected to each electrode needle Np of the positive electrode unit 6 by a harness Hp. Then, a voltage Vp corresponding to the voltage signal Vip input to the primary circuit 931 is applied from the secondary circuit 932 to each electrode needle Np via the harness Hp.

[0063] Within housing 2, the aforementioned ground G (internal ground) is provided. The rear frame 25, which is made of antistatic resin, is short-circuited to this ground G. Note that the method of electrically connecting the rear frame 25 and ground G is not limited to a short circuit; they may also be connected via a resistor.

[0064] Furthermore, the electrode unit controller 9 has a ground electrode Te short-circuited to earth E (external ground) and a low-response detection circuit 94 provided between the ground electrode Te and ground G. The low-response detection circuit 94 has a detection resistor R94 connecting the ground electrode Te and ground G. This detection resistor R94 is provided to detect the current Idl flowing from earth E to the static elimination device 1 via the ground electrode Te. In other words, if there is a difference in the amount of negative ions and positive ions released from the static elimination device 1, a charge corresponding to this difference flows from earth E to the ground electrode Te, and a current Idl due to this charge flows through the detection resistor R94. As a result, a voltage Vdl corresponding to the current Idl is generated at the detection point 941 between the detection resistor R94 and ground G. In this way, the low-response detection circuit 94 converts the current Idl due to the charge flowing from earth E to the housing 2 via the ground electrode Te into a voltage Vdl using the detection resistor R94. In other words, the low-response detection circuit 94 detects a voltage Vdl that indicates the ion balance of negative and positive ions generated by the static elimination device 1 and absorbed by the earth E.

[0065] Furthermore, the electrode unit controller 9 has a high-response detection circuit 95 provided between the front mesh 115 and the ground G. The high-response detection circuit 95 has a detection resistor R95 connecting the front mesh 115 and the ground G. This detection resistor R95 is provided to detect the current Idh flowing from the front mesh 115 to the ground G. In other words, negative and positive ions generated around the electrode needles Nm and Np move in the airflow direction Dw and reach the front mesh 115. Some of the negative and positive ions that reach the front mesh 115 are absorbed by the front mesh 115. As a result, a charge corresponding to the difference in the amount of negative and positive ions absorbed by the front mesh 115 flows from the front mesh 115 to the ground G, and a current Idh due to this charge flows through the detection resistor R95. Consequently, a voltage Vdh corresponding to the current Idh is generated at the detection point 951 between the detection resistor R95 and the front mesh 115. In this way, the high-response detection circuit 95 converts the current Idh caused by the charge flowing from the front wire mesh 115 to ground G into a voltage Vdh using the detection resistor R95. In other words, the high-response detection circuit 95 detects a voltage Vdh that indicates the ion balance of negative and positive ions generated by the static eliminator 1 and absorbed by the front wire mesh 115.

[0066] Here, the detection resistor R94 of the low-response detection circuit 94 is greater than the detection resistor R95 of the high-response detection circuit 95. Also, the capacitance of the earth E is greater than the capacitance of the front wire mesh 115. Therefore, the time constant of the high-response detection circuit 95 is smaller than the time constant of the low-response detection circuit 94. In other words, the response speed of the high-response detection circuit 95 is faster than the response speed of the low-response detection circuit 94. That is, the high-response detection circuit 95 detects high-frequency fluctuations in the ion balance, while the low-response detection circuit 94 detects low-frequency fluctuations in the ion balance that are lower than those high frequencies.

[0067] The electrode unit controller 9 controls the ion balance by performing feedback control on the voltages Vm and Vp applied to the electrode needles Nm and Np, based on the fluctuations in ion balance detected by the low-response detection circuit 94 and the high-response detection circuit 95. Specifically, the electrode unit controller 9 has a second balance control unit 96 that controls the balance between negative and positive ions (ion balance) generated by the application of voltages Vp and Vm to the electrode needles Np and Nm in order to suppress fluctuations (wobble) in the ion balance, and feedback control is performed by this second balance control unit 96.

[0068] More specifically, the low-response detection circuit 94 outputs a voltage Vdl, which indicates fluctuations in ion balance at low frequencies, to the first balance control unit 912 of the CPU 91. The first balance control unit 912 holds a target voltage Vtl, which is a target value of the voltage Vdl, and generates a voltage signal Vs corresponding to the difference between the voltage Vdl and the target voltage Vtl, and outputs this voltage signal Vs to the second balance control unit 96. Incidentally, the target voltage Vtl is set to zero volts. In other words, the target state is when the amounts of negative ions and positive ions emitted from the static eliminator 1 are equal, and the charge flowing from earth E into the static eliminator 1 becomes zero.

[0069] Furthermore, the high-response detection circuit 95 outputs a voltage Vdh, which indicates fluctuations in the ion balance at high frequencies, to the second balance control unit 96. In response, the second balance control unit 96 holds a target voltage Vth, which is the target value of the voltage Vdh, and generates a voltage signal Vim, which is a control signal for feedback control of the voltage Vm according to the difference between the voltage Vdh and the target voltage Vth and the voltage signal Vs, and outputs the voltage signal Vim to the primary circuit 921 of the negative polarity high-voltage power supply 92. Incidentally, the target voltage Vth is not zero volts, but is set to a voltage that is shifted from zero by a predetermined offset voltage. In other words, there is a difference between the ease with which the front mesh 115 absorbs negative ions and the ease with which the front mesh 115 absorbs positive ions. Therefore, in the target state where equal amounts of negative ions and positive ions reach the front mesh 115, the current Idh is not zero, and the voltage Vdh is shifted by the offset voltage Vo (offset amount) relative to the ground G voltage (zero volts). Therefore, the target voltage Vth of voltage Vdh is set to the offset voltage Vo. The offset voltage Vo is set in the second balance control unit 96 according to the voltage signal Vs, which reflects the change in the generation ratio of positive ions and negative ions due to changes in the state (wear, etc.) of the electrode needles Np and Nm.

[0070] In this way, feedback control is performed to converge the voltage Vdl toward the target voltage Vtl, and feedback control is performed to converge the voltage Vdh toward the target voltage Vth. In other words, feedback control is performed to converge the current Idl toward the target current Itl (=Vtl / R97), and feedback control is performed to converge the current Idh toward the target current Ith (=Vth / R95). The second balance control unit 96 that performs such control may be composed of an analog circuit such as an operational amplifier, or a digital circuit such as a processor.

[0071] Furthermore, the electrode unit controller 9 uses the rear wire mesh 125 to control the application of voltages Vp and Vm to the electrode needles Np and Nm, which are necessary and sufficient for the electrode needles Np and Nm to generate corona discharge. More specifically, since the rear wire mesh 125 is short-circuited to ground G, any charge generated on the rear wire mesh 125 flows from the rear wire mesh 125 to ground G. Note that the method of electrically connecting the rear wire mesh 125 and ground G is not limited to a short circuit; they may also be connected via a resistor.

[0072] Specifically, a current Irn, corresponding to the charge generated by the corona discharge, flows from the rear wire mesh 125 to ground G along the circuit formed by the corona discharge between the electrode needle Nm and the rear wire mesh 125. Also, a current Irp, corresponding to the charge generated by the corona discharge, flows from the rear wire mesh 125 to ground G along the circuit formed by the corona discharge between the electrode needle Np and the rear wire mesh 125. In contrast, the secondary circuit 922 of the negative polarity high-voltage power supply 92 is connected to ground G, and the secondary circuit 932 of the positive polarity high-voltage power supply 93 is connected to ground G. Therefore, the current Ign, mainly current Irn that reaches ground G from the rear wire mesh 125, flows from ground G to the secondary circuit 922, and the current Igp, mainly current Irp that reaches ground G from the rear wire mesh 125, flows from ground G to the secondary circuit 932.

[0073] Furthermore, the electrode unit controller 9 has a discharge amount detection circuit 97 provided between the secondary circuit 932 of the positive polarity high-voltage power supply 93 and ground G. The discharge amount detection circuit 97 has a detection resistor R97 that connects this secondary circuit 932 and ground G. Therefore, the current Igp flowing from ground G to the secondary circuit 932 flows through the detection resistor R97. As a result, a voltage Vgp corresponding to the current Igp is generated at the detection point 971 between the detection resistor R97 and the secondary circuit 932. In this way, the discharge amount detection circuit 97 converts the current Igp flowing from the rear wire mesh 125 through ground G to the secondary circuit 932 of the positive polarity high-voltage power supply 93 into a voltage Vgp using the detection resistor R97. In other words, the discharge amount detection circuit 97 detects a voltage Vgp that indicates the amount of positive ions generated in response to the application of a voltage Vp to the electrode needle Np.

[0074] The discharge amount detection circuit 97 outputs the detected voltage Vgp to the high voltage control unit 911 of the CPU 91. The high voltage control unit 911 holds the target voltage Vtp, which is the target value of the voltage Vgp, and generates a voltage signal Vip, which is a control signal for feedback control of the voltage Vp according to the difference between the voltage Vgp and the target voltage Vtp, and outputs the voltage signal Vip to the primary circuit 931 of the positive polarity high voltage power supply 93. This performs feedback control to converge the voltage Vgp toward the target voltage Vtp. As a result, an amount of positive ions corresponding to the target voltage Vtp is generated around the electrode needle Np. As described above, feedback control to balance the generation amounts of negative ions and positive ions is also performed by the second balance control unit 96, etc. Therefore, negative ions are generated around the electrode needle Nm to follow the positive ions generated around the electrode needle Np. As a result, an amount of negative ions corresponding to the target voltage Vtp is generated around the electrode needle Nm. This control system increases the voltage applied to the electrode needles Nm and Np as wear progresses, thereby maintaining a constant amount of negative and positive ions generated in response to corona discharge by the electrode needles Nm and Np.

[0075] Figure 11B is a flowchart showing an example of voltage control performed in the operation of Figure 10. In step S201, the target voltage Vtl for controlling the ion balance in the long term and the target voltage Vth for controlling the ion balance in the short term are acquired by the first balance control unit 912 and the second balance control unit 96. Then, in step S202, the voltage Vdl detected by the low-response detection circuit 94 is acquired by the first balance control unit 912, and in step S203, the voltage Vdh detected by the high-response detection circuit 95 is acquired by the second balance control unit 96. Then, when the voltage Vdl changes by a certain amount (if "YES" is answered in step S204), the second balance control unit 96 performs feedback control based on the target voltage Vtl and voltage Vdl, and feedback control based on the target voltage Vth and voltage Vdh, and inputs the voltage signal Vim to the negative polarity high-voltage power supply 92 (step S205). If the voltage Vdl does not change by a certain amount (if the answer is "NO" in step S204), the second balance control unit 96 performs feedback control based on the target voltage Vth and voltage Vdh and inputs the voltage signal Vim to the negative polarity high voltage power supply 92 (step S206).

[0076] The static elimination device 1 described above is provided with electrode needles Np and Nm (ion generation unit) that generate positive and negative ions, and a positive high-voltage power supply 93 and a negative high-voltage power supply 92 (high-voltage application unit) that apply voltage Vp (positive high voltage) and voltage Vm (negative high voltage) to the electrode needles Np and Nm. When the positive high-voltage power supply 93 applies voltage Vp to the electrode needle Np, positive ions are generated around the electrode needle Np, and when the negative high-voltage power supply 92 applies voltage Vm to the electrode needle Nm, negative ions are generated around the electrode needle Nm. In addition, the current Idl (first ion current) flowing between the earth E and the static elimination device 1 via the ground electrode Te is detected, and feedback control is performed on the negative high-voltage power supply 92 so that the current Idl becomes the target current Itl (first target value). This feedback control based on the current Idl allows for appropriate control of the long-term ion balance. Furthermore, a front wire mesh 115, which functions as a sensing electrode different from the ground electrode Te, is positioned at the location where the positive and negative ions generated by the electrode needles Np and Nm reach. The current Idh (second ion current) generated by the positive and negative ions that reach this front wire mesh 115 is detected, and feedback control is performed on the negative polarity high-voltage power supply 92 so that the current Idh becomes the target current Ith (second target value). This feedback control based on the current Idh allows for appropriate control of the short-term ion balance. In this way, it is possible to appropriately control both the long-term and short-term ion balance.

[0077] Furthermore, the low-response detection circuit 94 (first detection circuit) has a detection resistor R94 (first resistor) through which a current Idl flows, and detects the current Idl based on the voltage Vdl (first voltage) generated across the detection resistor R94 when the current Idl flows. Furthermore, the high-response detection circuit 95 (second detection circuit) has a detection resistor R95 (second resistor) through which a current Idh flows, and detects the current Idh based on the voltage Vdh (second voltage) generated across the detection resistor R95 when the current Idh flows. In this case, the resistance value of the detection resistor R94 is greater than the resistance value of the detection resistor R95. In this configuration, since the resistance value of the detection resistor R94 is greater than the resistance value of the detection resistor R95, the responsiveness of the system that detects the current Idh using the detection resistor R95 can be made higher than the responsiveness of the system that detects the current Idl using the detection resistor R94. This allows for appropriate control of the long-term ion balance (in other words, the low-frequency component of the ion balance) based on the current Idl detected by the detection resistor R94, and appropriate control of the short-term ion balance (in other words, the high-frequency component of the ion balance) based on the current Idh detected by the detection resistor R95.

[0078] Furthermore, a fan 33 is provided to generate airflow in the airflow direction Dw, and the front wire mesh 115 is positioned downstream of the electrode needles Np and Nm in the airflow direction Dw. In this configuration, the positive and negative ions generated by the electrode needles Np and Nm can be reliably delivered to the front wire mesh 115 by the airflow generated by the fan 33 in the airflow direction Dw.

[0079] Furthermore, the fan 33 is positioned between the electrode needles Np and Nm and the front wire mesh 115 in the airflow direction Dw. In this configuration, the positive and negative ions generated by the electrode needles Np and Nm reach the front wire mesh 115 in a uniformly dispersed state due to the stirring by the fan 33. Therefore, it becomes possible to stably detect the current Idh.

[0080] Furthermore, the target current Ith of the current Idh is a value that is shifted from zero by a predetermined offset amount (=Vo / R95). In other words, when equal amounts of positive and negative ions reach the front mesh 115, due to the characteristics of the front mesh 115, the value of the current Idh does not become zero, but rather the current Idh has a constant offset amount. By setting this offset amount as the target current Ith, the short-term ion balance can be appropriately controlled.

[0081] Furthermore, the device is equipped with an electrode needle Np (positive electrode needle) having a tip that generates corona discharge in response to the application of voltage Vp, and an electrode needle Nm (negative electrode needle) having a tip that generates corona discharge in response to the application of voltage Vm. Positive ions are generated by the corona discharge from electrode needle Np, and negative ions are generated by the corona discharge from electrode needle Nm. In addition, a positive polarity high-voltage power supply 93 (positive polarity high-voltage application circuit) is connected to electrode needle Np and applies voltage Vp to electrode needle Np, and a negative polarity high-voltage power supply 92 (negative polarity high-voltage application circuit) is connected to electrode needle Nm and applies voltage Vm to electrode needle Nm. With this configuration, the ion balance between positive ions generated by the corona discharge from electrode needle Np and negative ions generated by the corona discharge from electrode needle Nm can be appropriately controlled both in the long term and in the short term.

[0082] Furthermore, a discharge amount detection circuit 97 (ion amount detection unit) is provided to detect a voltage Vgp indicating the amount of positive ions generated by the electrode needle Np (one electrode needle) through corona discharge. The high voltage control unit 911 then performs feedback control based on the voltage Vgp (amount of ions) detected by the discharge amount detection circuit 97 with respect to the voltage Vp applied to the electrode needle Np by the positive polarity high voltage power supply 93 (one high voltage application circuit) connected to the electrode needle Np, thereby converging the amount of positive ions generated by the electrode needle Np to a predetermined amount (an amount corresponding to the target voltage Vtp). In addition, the second balance control unit 96 (feedback control unit) performs feedback control on the negative polarity high voltage power supply 92 (the other high voltage application circuit) to control the current Idl detected by the low response detection circuit 94 so that it becomes the target current Itl, and feedback control to control the current Idh detected by the high response detection circuit 95 so that it becomes the target current Ith. In this configuration, control is performed on the positive-polarity high-voltage power supply 93 to generate a constant amount of ions regardless of the wear progression of the electrode needles Np and Nm, and control is performed on the negative-polarity high-voltage power supply 92 to achieve an appropriate ion balance. By separating the target of the control according to the content of the control, the control can be simplified.

[0083] As described above, in this embodiment, the static elimination device 1 corresponds to an example of the "static elimination device" of the present invention, the front wire mesh 115 corresponds to an example of the "detection electrode" of the present invention, the fan 33 corresponds to an example of the "fan" of the present invention, the negative polarity high voltage power supply 92 and the positive polarity high voltage power supply 93 cooperate to function as an example of the "high voltage application unit" of the present invention, the negative polarity high voltage power supply 92 corresponds to an example of the "negative polarity high voltage application circuit" of the present invention, the positive polarity high voltage power supply 93 corresponds to an example of the "positive polarity high voltage application circuit" of the present invention, the low response detection circuit 94 corresponds to an example of the "first detection circuit" of the present invention, the high response detection circuit 95 corresponds to an example of the "second detection circuit" of the present invention, the high voltage control unit 911 corresponds to an example of the "high voltage control unit" of the present invention, the balance control unit 912 and the second balance control unit 96 cooperate to function as an example of the "feedback control unit" of the present invention, and the discharge amount detection cycle Path 97 corresponds to an example of the "ion quantity detection unit" of the present invention, airflow direction Dw corresponds to an example of the "airflow direction" of the present invention, earth E corresponds to an example of the "earth" of the present invention, ground electrode Te corresponds to an example of the "ground electrode" of the present invention, current Idl corresponds to an example of the "first ion current" of the present invention, current Idh corresponds to an example of the "second ion current" of the present invention, target current Itl corresponds to an example of the "first target value" of the present invention, target current Ith corresponds to an example of the "second target value" of the present invention, electrode needles Np and Nm correspond to an example of the "ion generation unit" of the present invention, electrode needle Np corresponds to an example of the "positive electrode needle" of the present invention, electrode needle Nm corresponds to an example of the "negative electrode needle" of the present invention, detection resistance R94 corresponds to an example of the "first resistance" of the present invention, detection resistance R95 corresponds to an example of the "second resistance" of the present invention, and voltage Vp corresponds to an example of the "positive polarity high voltage" of the present invention. Voltage Vm corresponds to an example of the "negative polarity high voltage" of the present invention, voltage Vdl corresponds to an example of the "first voltage" of the present invention, and voltage Vdh corresponds to an example of the "second voltage" of the present invention.

[0084] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made to those described above without departing from the spirit of the invention. For example, the first unit frame 51 and the second unit frame 61 do not need to be arc-shaped, and may be circular.

[0085] Furthermore, the arrangement of the electrode needles Nm and Np in the first and second unit frames 51 and 61 may be changed. For example, the electrode needles Nm and Np may be provided so as to protrude outward from the outer walls 512 and 612 of the first and second unit frames 51 and 61.

[0086] Furthermore, the number or arrangement of the electrode needles Nm and Np may be changed as appropriate.

[0087] Alternatively, the arrangement order of the negative electrode unit 5 and the positive electrode unit 6 in the X direction may be reversed.

[0088] Alternatively, the fan unit 3 may be positioned upstream of the negative electrode unit 5 and the positive electrode unit 6 in the airflow direction Dw.

[0089] Furthermore, the specific details of the ion generation amount control performed by the high-voltage control unit 911 are not limited to the above example. In other words, the ion generation amount may be controlled by performing feedback control on the voltage Vm based on the current Ign flowing from ground G to the secondary circuit 922 of the negative polarity high-voltage power supply 92.

[0090] Furthermore, control (by the high-voltage control unit 911) is performed on the positive-polarity high-voltage power supply 93 to generate a predetermined amount of ions regardless of the wear progression of the electrode needles Nm and Np, while control (by the second balance control unit 96) is performed on the negative-polarity high-voltage power supply 92 to achieve an appropriate ion balance. However, the former control may be performed on the negative-polarity high-voltage power supply 92, and the latter control may be performed on the positive-polarity high-voltage power supply 93.

[0091] Furthermore, two types of electrode needles, Np and Nm, are provided to which different DC voltages Vp and Vm are applied, respectively. Positive ions are generated by electrode needle Np, and negative ions are generated by electrode needle Nm. However, positive and negative ions may also be generated by corona discharge caused by applying a time-varying AC voltage between voltages Vp and Vm to a single type of electrode needle.

[0092] Furthermore, the negative electrode unit 5 and the positive electrode unit 6 may be configured as shown in Figure 12. Here, Figure 12 is a schematic perspective view showing modified examples of the negative electrode unit and the positive electrode unit. In the modified example shown in Figure 12, the negative electrode unit 5 has a first unit frame 51 having a flat plate shape extending in the Y direction, and a plurality of electrode needles Nm are arranged in the Y direction on the rear end surface of the first unit frame 51. Each electrode needle Nm protrudes from the rear end surface of the first unit frame 51 to the rear side Xb in the X direction. The positive electrode unit 6 has a second unit frame 61 having a flat plate shape extending in the Y direction, and a plurality of electrode needles Np are arranged in the Y direction on the rear end surface of the second unit frame 61. Each electrode needle Np protrudes from the rear end surface of the second unit frame 61 to the rear side Xb in the X direction. The electrode needles Nm and Np generate negative ions and positive ions when a voltage is applied. These negative ions and positive ions are discharged from the static elimination device 1 by airflow in the airflow direction Dw parallel to the X direction.

[0093] In this modified example, the system comprises a negative electrode unit 5 (first electrode unit) having multiple electrode needles Nm (first electrode needles) arranged in the Y direction (needle arrangement direction), and a positive electrode unit 6 having multiple electrode needles Np (second electrode needles) arranged in the Y direction. Thus, the electrode needles Nm and Np are provided in different negative electrode unit 5 and positive electrode unit 6, respectively. Therefore, the creepage distance between electrode needle Nm and electrode needle Np is the distance of the path from electrode needle Nm to electrode needle Np via the negative electrode unit 5 and positive electrode unit 6. This allows for a wide creepage distance to be secured. Furthermore, the negative electrode unit 5 and positive electrode unit 6 are aligned in the Z direction (unit arrangement direction), or in other words, they are adjacent in the Z direction. Therefore, the spatial distance between the electrode needle Nm of the negative electrode unit 5 and the electrode needle Np of the positive electrode unit 6 can be reduced. As a result, it is possible to suppress the progression of wear on electrode needles Nm and Np by ensuring a sufficient creepage distance between them to prevent abnormal discharge, while simultaneously reducing the voltage required for corona discharge by minimizing the spatial distance between them.

[0094] Furthermore, the static elimination device 1 described above is equipped with a system for long-term feedback control of the ion balance and a system for short-term feedback control of the ion balance. The specific configuration for implementing these two feedback control systems is not limited to the example shown in Figure 11A. In other words, any configuration that realizes the two feedback systems conceptually shown in Figure 13 can be adopted.

[0095] Figure 13 schematically shows two systems that perform long-term and short-term feedback. Positive and negative ions, whose ion balance is controlled by the ion output control 981, are released from the housing 2 through the front cover 11 into the external target space. A first ion balance 982, which indicates the ion balance in the target space, is then detected, and this first ion balance 982 is fed back to the ion output control 981 by the feedback loop 983. The ion output control 981 performs long-term feedback control (i.e., low-response feedback control) on the ion balance released from the ion output control 981 in order to bring the first ion balance 982 closer to the target value.

[0096] Furthermore, a second ion balance 984, which indicates the ion balance at a different location from the first ion balance 982 (for example, inside the front cover 11), is detected, and this second ion balance 984 is fed back to the ion output control 981 by the feedback loop 985. The ion output control 981 performs short-term feedback control (i.e., high-response feedback control) based on the second ion balance 984 with respect to the ion balance emitted from the ion output control 981.

[0097] In other words, a first feedback control based on the first ion balance 982 and a second feedback control based on the second ion balance 984 are performed, and the responsiveness of the second feedback control is higher than that of the first feedback control. This allows for the proper maintenance of ion balance in both the long and short term.

[0098] Furthermore, to perform long-term feedback control, an ion balance sensor as shown in Figure 14 may be used. Figure 14 is a perspective view showing an example of an ion balance sensor. The ion balance sensor 99 in Figure 14 has a sensor plate 991 for detecting ion balance and an output terminal 992 that outputs a current (first ion current) corresponding to the ion balance detected by the sensor plate 991. At least the sensor plate 991 of this ion balance sensor 99 is located at an external detection position outside the main body of the static elimination device 1, which is composed of a housing 2 and a front cover 11. The ion balance at the external detection position (i.e., the first ion balance 982) is detected by the sensor plate 991, and the first ion current is output from the output terminal 992. The first ion current output from the output terminal 992 is fed back to the ion output control 981 by a feedback loop 983.

[0099] When an ion balance sensor 99 is used with the electrode unit controller 9 in Figure 11A, the first ion current output from the output terminal 992 of the ion balance sensor 99 is input to a detection resistor, for example, that is connected in parallel with the detection resistor R94, and the first ion current is converted into a voltage by this detection resistor. Then, feedback control is performed by the first balance control unit 912 and the second balance control unit 96 so that the voltage corresponding to the first ion current becomes a predetermined target voltage (in other words, so that the first ion current becomes a predetermined target current). Note that the voltage Vdl converted from the current Idl from earth E is not reflected in the feedback control and is ignored. In other words, the first balance control unit 912 and the second balance control unit 96 perform long-term feedback control based on the first ion current detected by the ion balance sensor 99, not the current Idl from earth E. In this modified example, the ion balance sensor 99 corresponds to an example of the "first detection circuit" of the present invention. [Industrial applicability]

[0100] This invention is applicable to all technologies that discharge ions generated by applying a voltage to an electrode onto an object to remove static electricity from that object. [Explanation of symbols]

[0101] 1...Static eliminator 115...Front wire mesh (detection electrode) 33...fan Dw...Airflow direction Nm... Electrode needle (ion generating unit, negative electrode needle) Np... Electrode needle (ion generating unit, positive electrode needle) Vm…Voltage (negative polarity high voltage) Vp…Voltage (positive high voltage) 92... Negative polarity high voltage power supply (high voltage application section, negative polarity high voltage application circuit) 911... High-voltage control unit (High-voltage control unit) 912... Balance control unit (feedback control unit) E... Earth Te…ground electrode 94...Low-response detection circuit (first detection circuit) R94...Detection resistor (first resistor) Idl…electric current (first ion current) Vdl…Voltage (first voltage) 95... High-response detection circuit (second detection circuit) R95...Detection resistor (second resistor) Idh... Electric current (second ion current) Vdh…Voltage (second voltage) 96...Second balance control unit (feedback control unit) Itl…Target current (first target value) Ith…Target current (second target value) 97...Discharge amount detection circuit (ion amount detection unit)

Claims

1. A static elimination device that releases ions to an object to remove static electricity from that object, An ion generating unit that generates positive ions by generating corona discharge in response to the application of a positive polarity high voltage, and generates negative ions by generating corona discharge in response to the application of a negative polarity high voltage, A high-voltage application unit that applies the positive high voltage and the negative high voltage to the ion generating unit, The grounding electrode is short-circuited to earth, A first detection circuit for detecting a first ion current flowing between the earth and the static elimination device via the ground electrode, A detection electrode, different from the ground electrode, is positioned at a location where the positive and negative ions generated by the ion generating unit reach, A second detection circuit for detecting a second ion current generated by the positive and negative ions that have reached the detection electrode, A feedback control unit that performs feedback control on the high voltage application unit so that the first ion current detected by the first detection circuit becomes a first target value, and the second ion current detected by the second detection circuit becomes a second target value. Equipped with, The first detection circuit has a first resistor through which the first ion current flows, and detects the first ion current based on the first voltage generated across the first resistor when the first ion current flows. The second detection circuit has a second resistor through which the second ion current flows, and detects the second ion current based on the second voltage generated across the second resistor when the second ion current flows. A static eliminator in which the resistance value of the first resistor is greater than the resistance value of the second resistor.

2. It also features a fan that generates airflow in the direction of the airflow, The static elimination device according to claim 1, wherein the detection electrode is arranged downstream of the ion generating unit in the airflow direction.

3. The static elimination device according to claim 2, wherein the fan is arranged between the ion generating unit and the detection electrode in the direction of airflow.

4. The static elimination device according to claim 1, wherein the second target value is a value shifted from zero by a predetermined offset amount.

5. The ion generating unit comprises a positive electrode needle having a tip that generates corona discharge in response to the application of the positive high voltage, and a negative electrode needle having a tip that generates corona discharge in response to the application of the negative high voltage, wherein positive ions are generated by the corona discharge of the positive electrode needle, and negative ions are generated by the corona discharge of the negative electrode needle. The static elimination device according to any one of claims 1 to 4, wherein the high voltage application unit comprises a positive polarity high voltage application circuit connected to the positive electrode needle for applying the positive polarity high voltage to the positive electrode needle, and a negative polarity high voltage application circuit connected to the negative electrode needle for applying the negative polarity high voltage to the negative electrode needle.

6. An ion quantity detection unit for detecting the amount of ions generated by corona discharge from one of the electrode needles, the positive electrode needle and the negative electrode needle, A high-voltage control unit, comprising a positive-polarity high-voltage application circuit and a negative-polarity high-voltage application circuit, which is connected to one of the electrode needles, performs feedback control based on the amount of ions detected by the ion amount detection unit with respect to the voltage applied to the one electrode needle, thereby converging the amount of ions generated by the one electrode needle to a predetermined amount. Furthermore, The static elimination device according to claim 5, wherein the feedback control unit performs feedback control to control the first ion current detected by the first detection circuit to a first target value, and feedback control to control the second ion current detected by the second detection circuit to a second target value, on the other high voltage application circuit among the positive high voltage application circuit and the negative high voltage application circuit.

7. An ion balance control method for controlling the ion balance of ions released from a static elimination device to an object in order to eliminate static electricity from the object, A process of applying the positive high voltage and the negative high voltage from a high voltage application unit to an ion generating unit that generates positive ions by generating corona discharge in response to the application of a positive high voltage, and generates negative ions by generating corona discharge in response to the application of a negative high voltage, A step of detecting a first ion current flowing between the ground and the static elimination device via a grounding electrode short-circuited to the ground, A step of detecting a second ion current generated by the positive ions and negative ions that have reached a detection electrode different from the ground electrode, which is positioned at the location where the positive ions and negative ions generated by the ion generating unit reach; The process involves performing feedback control on the high-voltage application unit so that the first ion current reaches a first target value, and performing feedback control on the high-voltage application unit so that the second ion current reaches a second target value. Equipped with, In the step of detecting the first ion current, a first detection circuit having a first resistor through which the first ion current flows detects the first ion current based on a first voltage generated across the first resistor as the first ion current flows. An ion balance control method comprising the step of detecting the second ion current, wherein a second detection circuit having a second resistor with a resistance value smaller than the resistance value of the first resistor detects the second ion current based on a second voltage generated across the second resistor as a result of the flow of the second ion current.

8. A static elimination device that discharges ions onto an object to remove static electricity from the object, An ion generating unit that generates positive ions by generating corona discharge in response to the application of a positive polarity high voltage, and generates negative ions by generating corona discharge in response to the application of a negative polarity high voltage, A high-voltage application unit that applies the positive high voltage and the negative high voltage to the ion generating unit, The grounding electrode is short-circuited to earth, A first detection circuit for detecting a first ion current flowing between the earth and the static elimination device via the ground electrode, A detection electrode, different from the ground electrode, is positioned at a location where the positive and negative ions generated by the ion generating unit reach, A second detection circuit for detecting a second ion current generated by the positive and negative ions that have reached the detection electrode, A feedback control unit that performs feedback control on the high voltage application unit so that the first ion current detected by the first detection circuit becomes a first target value, and the second ion current detected by the second detection circuit becomes a second target value. Equipped with, The ion generating unit comprises a positive electrode needle having a tip that generates corona discharge in response to the application of the positive high voltage, and a negative electrode needle having a tip that generates corona discharge in response to the application of the negative high voltage, wherein positive ions are generated by the corona discharge of the positive electrode needle, and negative ions are generated by the corona discharge of the negative electrode needle. The static elimination device comprises a positive polarity high voltage application circuit connected to the positive electrode needle for applying the positive polarity high voltage to the positive electrode needle, and a negative polarity high voltage application circuit connected to the negative electrode needle for applying the negative polarity high voltage to the negative electrode needle.

9. A static elimination device that releases ions to an object to remove static electricity from that object, An ion generating unit that generates positive ions by generating corona discharge in response to the application of a positive polarity high voltage, and generates negative ions by generating corona discharge in response to the application of a negative polarity high voltage, A high-voltage application unit that applies the positive high voltage and the negative high voltage to the ion generating unit, A first detection circuit that detects a first ion current corresponding to the ratio of positive ions and negative ions generated by the ion generating unit, which reaches a predetermined area outside the main body of the static elimination device, A detection electrode is positioned at the location where the positive and negative ions generated by the ion generating unit reach, A second detection circuit for detecting a second ion current generated by the positive and negative ions that have reached the detection electrode, A feedback control unit that performs feedback control on the high voltage application unit so that the first ion current detected by the first detection circuit becomes a first target value, and the second ion current detected by the second detection circuit becomes a second target value. A static elimination device equipped with the following features.

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