Patent Application
20240079857
The present application claims foreign priority based on Japanese Patent Application No. 2022-142588, filed Sep. 7, 2022, the contents of which are incorporated herein by reference.
The invention relates to a technique for controlling ion balance of ions released from a static eliminator with respect to an object for static elimination of the object.
JP H10-289796 A discloses a static eliminator that applies positive and negative high voltages to positive and negative electrode needles, respectively, to generate a corona discharge, thereby generating positive ions and negative ions. In order to reliably eliminate static electricity of an object by such a static eliminator, it is important to equally balance a generation amount of positive ions and a generation amount of negative ions. Therefore, this static eliminator includes a detection resistor that detects a current flowing between the static eliminator and an earth, and performs feedback control on the positive and negative high voltages applied to the positive and negative electrode needles based on a voltage generated in the detection resistor.
As a result, it is possible to suppress a difference between the generation amount of positive ions and the generation amount of negative ions and to realize appropriate ion balance.
However, the feedback control based on the current between the static eliminator and the earth has low-responsiveness mainly due to the large capacitance of the earth. Therefore, the ion balance sometimes becomes unstable in the short term although the appropriate ion balance can be realized in the long term.
The invention has been made in view of the above problems, and an object thereof is to provide a technique capable of appropriately controlling both long-term ion balance and short-term ion balance.
According to one embodiment of the invention, a static eliminator that releases ions to an object to eliminate static electricity of the object, the static eliminator including: an ion generator that generates a corona discharge in response to application of a positive polarity high voltage to generate positive ions, and generates a corona discharge in response to application of a negative polarity high voltage to generate negative ions; a high voltage application unit that applies the positive polarity high voltage and the negative polarity high voltage to the ion generator; a ground electrode short-circuited to an earth; a first detection circuit that detects a first ion current flowing between the earth and the static eliminator via the ground electrode; a detection electrode different from the ground electrode, the detection electrode being arranged at a position where the positive ions and the negative ions generated by the ion generator arrive; a second detection circuit that detects a second ion current generated by the positive ions and the negative ions arriving at the detection electrode; and a feedback control unit that executes feedback control on the high voltage application unit to make the first ion current detected by the first detection circuit be a first target value, and executes feedback control on the high voltage application unit to make the second ion current detected by the second detection circuit be a second target value.
According to one embodiment of the invention, an ion balance control method for controlling ion balance of ions released from a static eliminator with respect to an object for static elimination of the object, the ion balance control method including: a step of applying a positive polarity high voltage and a negative polarity high voltage from a high voltage application unit to an ion generator that generates a corona discharge in response to the application of the positive polarity high voltage to generate positive ions, and generates a corona discharge in response to the application of the negative polarity high voltage to generate negative ions; a step of detecting a first ion current flowing between an earth and the static eliminator via a ground electrode short-circuited to the earth; a step of detecting a second ion current generated by the positive ions and the negative ions arriving at a detection electrode different from the ground electrode, the detection electrode being arranged at a position where the positive ions and the negative ions generated by the ion generator arrive; and a step of executing feedback control on the high voltage application unit to make the first ion current be a first target value, and executing feedback control on the high voltage application unit to make the second ion current be a second target value.
According to the invention (static eliminator and ion balance control method) configured as described above, the ion generator generating the positive ions and the negative ions, and the high voltage application unit applying the positive polarity high voltage and the negative polarity high voltage to the ion generator are provided. Then, the ion generator generates the positive ions when the high voltage application unit applies the positive polarity high voltage to the ion generator, and the ion generator generates the negative ions when the high voltage application unit applies the negative polarity high voltage to the ion generator. Further, the first ion current flowing between the earth and the static eliminator via the ground electrode is detected, and the feedback control is executed on the high voltage application unit such that the first ion current becomes the first target value. The feedback control based on the first ion current enables appropriate control of long-term ion balance. Furthermore, the detection electrode different from the ground electrode is arranged at the position where the positive ions and the negative ions generated by the ion generator arrive. Then, the second ion current generated by the positive ions and the negative ions arriving at the detection electrode is detected, and the feedback control is executed on the high voltage application unit such that the second ion current becomes the second target value. The feedback control based on the second ion current enables appropriate control of short-term ion balance. Thus, it is possible to appropriately control both the long-term ion balance and the short-term ion balance.
According to another embodiment of the invention, a static eliminator that releases ions to an object to eliminate static electricity of the object, the static eliminator including: an ion generator that generates a corona discharge in response to application of a positive polarity high voltage to generate positive ions, and generates a corona discharge in response to application of a negative polarity high voltage to generate negative ions; a high voltage application unit that applies the positive polarity high voltage and the negative polarity high voltage to the ion generator; a first detection circuit that detects a first ion current corresponding to a ratio between the positive ions and the negative ions generated by the ion generator, the first ion current reaching a predetermined region outside a device body of the static eliminator; a detection electrode arranged at a position where the positive ions and the negative ions generated by the ion generator arrive; a second detection circuit that detects a second ion current generated by the positive ions and the negative ions arriving at the detection electrode; and a feedback control unit that executes feedback control on the high voltage application unit to make the first ion current detected by the first detection circuit be a first target value, and executes feedback control on the high voltage application unit to make the second ion current detected by the second detection circuit be a second target value.
According to the invention (static eliminator) configured as described above, the ion generator generating the positive ions and the negative ions, and the high voltage application unit applying the positive polarity high voltage and the negative polarity high voltage to the ion generator are provided. Then, the ion generator generates the positive ions when the high voltage application unit applies the positive polarity high voltage to the ion generator, and the ion generator generates the negative ions when the high voltage application unit applies the negative polarity high voltage to the ion generator. Further, the first ion current, which reaches the predetermined region outside the device body of the static eliminator and corresponds to the ratio between the positive ions and the negative ions generated by the ion generator, is detected, and the feedback control is executed on the high voltage application unit such that the first ion current becomes the first target value. The feedback control based on the first ion current enables appropriate control of long-term ion balance. Furthermore, the detection electrode is arranged at the position where the positive ions and the negative ions generated by the ion generator arrive. Then, the second ion current generated by the positive ions and the negative ions arriving at the detection electrode is detected, and the feedback control is executed on the high voltage application unit such that the second ion current becomes the second target value. The feedback control based on the second ion current enables appropriate control of short-term ion balance. Thus, it is possible to appropriately control both the long-term ion balance and the short-term ion balance.
As described above, it is possible to appropriately control both the long-term ion balance and the short-term ion balance according to the invention.
A static eliminator 1 includes a front cover 11, a housing 2, a fan unit 3, a fixing 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 roughly divided into an upper part 2U and a lower part 2L provided on the lower side of the upper part 2U. An accommodation chamber 201 is provided in the upper part 2U of the housing 2, and an electrical equipment accommodating portion 202 is provided in the lower part 2L of the housing 2. The accommodation chamber 201 has a rectangular shape as viewed from the X direction and is open in the X direction. The fan unit 3, the fixing base 4, the negative electrode unit 5, the positive electrode unit 6, and the cleaning unit 7 are arrayed in the X direction and accommodated in the accommodation chamber 201. The electrical equipment accommodating portion 202 accommodates an electrical equipment system of the static eliminator 1. Further, the front cover 11 is attached to the housing 2 from the front side Xf so as to oppose the accommodation chamber 201, and the rear cover 12 is attached to the housing 2 from the rear side Xb so as to oppose the accommodation chamber 201.
The housing 2 includes 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 arrayed 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 electrically conductive. The antistatic resin can be formed by kneading an antistatic agent into a resin or coating a surface of a resin with an antistatic agent. The antistatic resin in the present embodiment is a resin having such a resistance value that an electric charge generated on a surface of the housing 2 flows to a ground G in a relatively short time, for example, several seconds when the housing 2 is made of the resin. An experimental result in which the electric charge generated on the surface of the housing 2 flows to the ground G in several seconds has been obtained when the housing 2 is made of a resin having a resistance value in the range of 109Ω to 1012Ω. Further, it is sufficient that most of an outer surface of the housing 2 is made of the antistatic resin. In the present embodiment, a display section 23 is not made of the antistatic resin, but charging of a part of the housing 2 has a small influence.
The front frame 21 includes a main frame 22 and the display section 23 provided on the front side Xf of the main frame 22. The main frames 22 and the display section 23 are arrayed in the X direction and attached to each other. The main frame 22 is open in the X direction. The display section 23 is provided in an opening of the main frame 22 in the lower part 2L and is arranged so as to be visually recognizable from the front side Xf. That is, the opening of the main frame 22 in a range of the upper part 2U constitutes a part of the accommodation chamber 201. Further, the main frame 22 in a range of the lower part 2L constitutes a part of the electrical equipment accommodating portion 202.
The rear frame 25 is open in the X direction. An opening of the rear frame 25 in a range of upper part 2U constitutes a part of the accommodation chamber 201. Further, the rear frame 25 in a range of the lower part 2L constitutes a part of the electrical equipment accommodating portion 202.
The front cover 11 includes a cover frame 111 made of an antistatic resin, and the cover frame 111 is attached to the front frame 21 of the housing 2 from the front side Xf in the upper part 2U. The cover frame 111 covers the accommodation chamber 201 from the front side Xf. Further, the cover frame 111 includes a mesh portion 112 provided with a plurality of slits, and the mesh portion 112 opposes the accommodation chamber 201 from the front side Xf. Further, a front wire mesh 115 (metal mesh) having a circular shape as viewed from the X direction is attached to the front frame 21. The front wire mesh 115 opposes the accommodation chamber 201 from the front side Xf and opposes the mesh portion 112 from the rear side Xb. The mesh portion 112 and the front wire mesh 115 allow passage of air in the X direction. Note that the cover frame 111 has the mesh portion 112 provided with the plurality of slits in the present embodiment, but may have any shape that can guide air generated by a fan 33, which will be described later, to a desired region. Further, the front cover 11 is attached to the housing 2, but a configuration in which the front cover 11 selected from a plurality of the front covers 11 having different shapes of the cover frame 111 is attached to the housing 2 may be adopted. According to this configuration, a user can attach the front cover 11 selected according to a use environment of the static eliminator 1 to the housing 2. For example, it is possible to attach the front cover 11 suitable for guiding the air to the vicinity in a case where a distance between the static eliminator 1 and an object to be neutralized is short and to attach the front cover 11 suitable for guiding the air far away in a case where the distance between the static eliminator 1 and the object to be neutralized is long. Furthermore, in the configuration in which the front cover 11 is switchable, a parameter regarding the operation of the static eliminator 1 may be set according to a type of the front cover 11 attached to the housing 2.
The rear cover 12 includes a cover frame 121 made of an antistatic resin, and the cover frame 121 is attached to the rear frame 25 of the housing 2 from the rear side Xb in the upper part 2U. The cover frame 111 has an opening 122 having a circular shape as viewed from the X direction, and the opening 122 opposes the accommodation chamber 201 from the rear side Xb. Furthermore, the rear cover 12 includes a rear wire mesh 125 (metal mesh) having a circular shape as viewed from the X direction. The rear wire mesh 125 is fitted into the opening 122 and attached to the cover frame 121, and opposes the accommodation chamber 201 from the rear side Xb. The rear wire mesh 125 allows passage of air in the X direction. Further, the rear wire mesh 125 is short-circuited to the ground G (
The fan unit 3 is arranged in the accommodation chamber 201 of the housing 2 and is located on the rear side Xb of the front wire mesh 115 of the front cover 11. The fan unit 3 includes a support frame 31 having a rectangular shape as viewed from the X direction, and the support frame 31 is arranged in the accommodation chamber 201 and attached to the housing 2. In the support frame 31, a ventilation opening 32 having a circular shape as viewed from the X direction is open in the X direction. The ventilation opening 32 opposes the front wire mesh 115 of the front cover 11 from the rear side Xb. Furthermore, the fan unit 3 includes the fan 33 having a circular shape as viewed from the X direction. The fan 33 includes a rotating shaft 331 provided parallel to the X direction and a plurality of blades 332 provided around the rotating shaft 331. Further, the fan 33 is arranged in the ventilation opening 32 of the support frame 31 and opposes the front wire mesh 115 of the front cover 11 from the rear side Xb. The fan 33 is supported by the support frame 31 so as to be rotatable about a rotation center parallel to the X direction, and rotates about the rotation center, thereby generating air (in other words, air flow) in an air blowing direction Dw from the rear side Xb toward the front side Xf in the X direction.
The fixing base 4 is arranged in the accommodation chamber 201 of the housing 2 and is located on the rear side Xb of the fan unit 3. The fixing base 4 includes a fixing frame 41 having a rectangular shape as viewed from the X direction, and the fixing frame 41 is arranged in the accommodation chamber 201 and attached to the housing 2. In the fixing frame 41, a ventilation opening 42 is open in the X direction. The ventilation opening 42 has a rectangular shape whose four corners are cut out in an arc shape as viewed from the X direction. Further, the fixing base 4 includes fixing portions 43, 44, 45, and 46 provided at four corners of the fixing frame 41. The fixing portions 43, 44, 45, and 46 are located on the outer side of the four corners of the ventilation opening 42, respectively. Furthermore, the fixing base 4 has an I-shaped part that supports the cleaning unit 7 with respect to the fixing frame 41 as will be described later.
The negative electrode unit 5 is arranged in the accommodation chamber 201 of the housing 2 and is fixed to the fixing frame 41 of the fixing base 4 from the rear side Xb. The negative electrode unit 5 has a configuration illustrated in
As illustrated in
Further, the negative electrode unit 5 has a plurality of (four) fixing portions 53, 54, 55, and 56 arrayed at a constant array pitch (90 degrees) in the circumferential direction Dc. In this example, the number of the electrode needles Nm is equal to the number of the fixing portions 53, 54, 55, and 56. The plurality of fixing portions 53, 54, 55, and 56 are arrayed along an outer wall 512 of the first unit frame 51, and protrude outward (in other words, to the opposite side of the center point Pc of the virtual circle Cv) from the outer wall 512. In the circumferential direction Dc, a phase of the array of the plurality of fixing portions 53, 54, 55, and 56 is shifted from a phase of the array of the plurality of electrode needles Nm. That is, the fixing portions 53, 54, 55, and 56 are provided at positions shifted from the electrode needles Nm in the circumferential direction Dc. The fixing portions 53, 54, 55, and 56 are respectively fastened to the fixing portions 43, 44, 45, and 46 of the fixing base 4 by screws S.
The air generated by the fan 33 of the fan unit 3 described above passes through a flow path Fw surrounded by the first unit frame 51 of the negative electrode unit 5 in the air blowing direction Dw. In other words, the first unit frame 51 of the negative electrode unit 5 has a curved shape (arc shape) so as to surround the flow path Fw through which the air generated by the fan 33 passes.
As illustrated in
As illustrated in
Further, the positive electrode unit 6 has a plurality of (four) fixing portions 63, 64, 65, and 66 arrayed at a constant array pitch (90 degrees) in the circumferential direction Dc. In this example, the number of the electrode needles Np is equal to the number of the fixing portions 63, 64, 65, and 66. The plurality of fixing portions 63, 64, 65, and 66 are arrayed along an outer wall 612 of the second unit frame 61, and protrude outward (in other words, to the opposite side of the center point Pc of the virtual circle Cv) from the outer wall 612. In the circumferential direction Dc, a phase of the array of the plurality of fixing portions 63, 64, 65, and 66 is shifted from a phase of the array of the plurality of electrode needles Np. That is, the fixing portions 63, 64, 65, and 66 are provided at positions shifted from the electrode needles Np in the circumferential direction Dc. The fixing portions 63, 64, 65, and 66 are respectively fastened to the fixing portions 43, 44, 45, and 46 of the fixing base 4 by screws S.
The air generated by the fan 33 of the fan unit 3 described above passes through the flow path Fw surrounded by the second unit frame 61 of the positive electrode unit 6 in the air blowing direction Dw. In other words, the second unit frame 61 of the positive electrode unit 6 has a curved shape (arc shape) so as to surround the flow path Fw through which the air generated by the fan 33 passes.
The negative electrode unit 5 and the positive electrode unit 6 are arrayed in the X direction in the accommodation chamber 201, and the positive electrode unit 6 is arranged on the rear side Xb of the negative electrode unit 5. Further, 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 each other as viewed from the X direction. It is sufficient that the fixing base 4 is a member that fixes the negative electrode unit 5 and the positive electrode unit 6 so as to have a desired arrangement relationship, and the fixing base 4 may be configured using a single member or a plurality of members. Further, another member such as a member constituting the housing 2 may also be configured to serve as the fixing base 4.
The fixing portion 43 has a protruding plate 431 protruding outward from the first and second unit frames 51 and 61 as viewed from the X direction. The protruding plate 431 protrudes to the upper left side from the first and second unit frames 51 and 61 in a rear view. Furthermore, the fixing portion 43 includes a fastening portion 432 protruding from the protruding plate 431 to the rear side Xb in the X direction and a fastening portion 433 protruding from the protruding plate 431 to the rear side Xb in the X direction. In the fastening portion 432, a screw hole 432h extending in the X direction is open to the rear side Xb. In the fastening portion 433, a screw hole 433h extending in the X direction is open to the rear side Xb. The screws S are screwed into the screw holes 432h and 433h. In the circumferential direction Dc, the fastening portion 432 and the fastening portion 433 are provided to be shifted from each other, and the fastening portion 432 is located on one side (clockwise side in the rear view) of the fastening portion 433.
The fixing portion 44 has a protruding plate 441 protruding outward from the first and second unit frames 51 and 61 as viewed from the X direction. The protruding plate 441 protrudes to the lower left side from the first and second unit frames 51 and 61 in the rear view. Furthermore, the fixing portion 44 includes a fastening portion 442 protruding from the protruding plate 441 to the rear side Xb in the X direction and a fastening portion 443 protruding from the protruding plate 441 to the rear side Xb in the X direction. In the fastening portion 442, a screw hole 442h extending in the X direction is open to the rear side Xb. In the fastening portion 443, a screw hole 443h extending in the X direction is open to the rear side Xb. The screws S are screwed into the screw holes 442h and 443h. In the circumferential direction Dc, the fastening portion 442 and the fastening portion 443 are provided to be shifted from each other, and the fastening portion 442 is located on one side (clockwise side in the rear view) of the fastening portion 443.
The fixing portion 45 has a protruding plate 451 protruding outward from the first and second unit frames 51 and 61 as viewed from the X direction. The protruding plate 451 protrudes to the lower right side from the first and second unit frames 51 and 61 in the rear view. Furthermore, the fixing portion 45 includes a fastening portion 452 protruding from the protruding plate 451 to the rear side Xb in the X direction and a fastening portion 453 protruding from the protruding plate 441 to the rear side Xb in the X direction. In the fastening portion 452, a screw hole 452h extending in the X direction is open to the rear side Xb. In the fastening portion 453, a screw hole 453h extending in the X direction is open to the rear side Xb. The screws S are screwed into the screw holes 452h and 453h. In the circumferential direction Dc, the fastening portion 452 and the fastening portion 453 are provided to be shifted from each other, and the fastening portion 452 is located on one side (clockwise side in the rear view) of the fastening portion 453.
The fixing portion 46 has a protruding plate 461 protruding outward from the first and second unit frames 51 and 61 as viewed from the X direction. The protruding plate 461 protrudes to the upper right side from the first and second unit frames 51 and 61 in the rear view. Furthermore, the fixing portion 46 includes a fastening portion 462 protruding from the protruding plate 461 to the rear side Xb in the X direction and a fastening portion 463 protruding from the protruding plate 441 to the rear side Xb in the X direction. In the fastening portion 462, a screw hole 462h extending in the X direction is open to the rear side Xb. In the fastening portion 463, a screw hole 463h extending in the X direction is open to the rear side Xb. The screws S are screwed into the screw holes 462h and 463h. In the circumferential direction Dc, the fastening portion 462 and the fastening portion 463 are provided to be shifted from each other, and the fastening portion 462 is located on one side (clockwise side in the rear view) of the fastening portion 463.
The fixing portions 53, 54, 55, and 56 of the negative electrode unit 5 are respectively fastened to the fastening portions 432, 442, 452, and 462 of the fixing base 4 with the screws S, respectively. Specifically, an insertion hole extending in the X direction is opened in the fixing portion 53. Then, 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 a state in which the insertion hole of the fixing portion 53 adjacent to the fastening portion 432 from the rear side Xb opposes the screw hole 432h of the fastening portion 432 in the X direction. Thus, the fixing portion 53 is fastened to the fastening portion 432. Further, the fixing portions 54, 55, and 56 are similarly fastened.
The fixing portions 63, 64, 65, and 66 of the positive electrode unit 6 are fastened to the fastening portions 433, 443, 453, and 463 of the fixing base 4 with the screws S, respectively. Specifically, an insertion hole extending in the X direction is opened in the fixing portion 63. Then, 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 a state in which the insertion hole of the fixing portion 63 adjacent to the fastening portion 433 from the rear side Xb opposes the screw hole 433h of the fastening portion 433 in the X direction. Thus, the fixing portion 63 is fastened to the fastening portion 433. Further, the fixing portions 64, 65, and 66 are similarly fastened.
Incidentally, the fastening portions 433, 443, 453, and 463 have the same length, and the fastening portions 432, 442, 452, and 462 have the same length. On the other hand, the fastening portions 433, 443, 453, and 463 are longer than the fastening portions 432, 442, 452, and 462. Therefore, the positive electrode unit 6 fastened to the fastening portions 433, 443, 453, and 463 is located on the rear side Xb of the negative electrode unit 5 fastened to the fastening portions 432, 442, 452, and 462. In particular, the lengths of the fastening portions 433, 443, 453, and 463 and the fastening portions 432, 442, 452, and 462 are set such that a gap is formed between the negative electrode unit 5 and the positive electrode unit 6 in the X direction.
Further, the number of the electrode needles Nm included in the negative electrode unit 5 and the number of the electrode needles Np included in the positive electrode unit 6 are equal (four), and the array pitch of the electrode needles Nm in the negative electrode unit 5 and the array pitch of the electrode needles Np in the positive electrode unit 6 are equal (90 degrees). On the other hand, for example, as illustrated in
The motor 72 is accommodated in a cylindrical part of the fixing base 4 centered on an axis parallel to the X direction. The rotating plate 73 has a disk shape centered on the axis. Further, the motor 72 and the rotating plate 73 are arranged at the center of the virtual circle Cv as viewed from the X direction, and a clearance CL is provided between each of the inner walls 511 and 611 of the first and second unit frames 51 and 61 and each of outer circumferences of the motor 72 and the rotating plate 73. This clearance CL opposes the plurality of blades 332 of the fan 33, and the air generated by the fan 33 passes through the clearance CL in the flow path Fw. The motor 72 has a rotating shaft passing through the center point Pc and parallel to the X direction, and the rotating plate 73 is provided coaxially with the motor 72. The rotating plate 73 is driven by the motor 72 to rotate in the circumferential direction Dc about the rotating shaft of the motor 72. In this example, the motor 72 is a stepping motor. However, a type of the motor 72 is not limited to this example.
The brush supporter 74 includes an attachment portion 741 attached to a back surface of the rotating plate 73, and a screw 742 for fastening the attachment portion 741 to the back surface of the rotating plate 73. A tip of the attachment portion 741 protrudes to the outer side of the rotating plate 73, and the brush supporter 74 includes an extending portion 743 extending from a tip of the rotating plate 73 to the front side Xf in the X direction, and two support portions 744m and 744p protruding from the extending portion 743 to the outer side in the radial direction around the center point Pc. Each of the support portions 744m and 744p extends from the extending portion 743 to the outer side of the rotating plate 73 in the radial direction. The support portions 744m and 744p are arrayed in the X direction, and the support portion 744p is located on the rear side Xb of the support portion 744m. Furthermore, the brush supporter 74 includes the brush holders 745m, 745p attached tips of the support portions 744m and 744p, respectively. The brush holders 745m and 745p are arrayed in the X direction, and the brush holder 745p is located on the rear side Xb of the brush holder 745m.
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 brush 71m and the cleaning brush 71p are provided to correspond to the electrode needles Nm and the electrode needles Np, respectively, and extend in the radial direction around the center point Pc. The cleaning brush 71m and the cleaning brush 71p are arrayed in the X direction, and the cleaning brush 71p is located on the rear side Xb of the cleaning brush 71m. The cleaning brush 71m opposes the inner wall 511 of the first unit frame 51, and the cleaning brush 71p opposes the inner wall 611 of the second unit frame 61. In such a configuration, the cleaning brushes 71m and 71p move in the circumferential direction Dc by a driving force of the motor 72. Then, the cleaning unit 7 cleans the electrode needles Nm and Np as follows by driving the cleaning brushes 71m and 71p by the motor 72.
That is, a plurality of cleaning positions Lm arrayed in the circumferential direction Dc are provided, and the plurality of cleaning positions Lm correspond to the plurality of electrode needles Nm, respectively. Then, the cleaning brush 71m is located at one cleaning position Lm corresponding to one electrode needle Nm to be cleaned among the plurality of electrode needles Nm, thereby coming into contact with the one electrode needle Nm. In particular, the motor 72 causes the cleaning brush 71m in contact with one electrode needle Nm at one cleaning position Lm to slightly reciprocate in the circumferential direction Dc, whereby dirt adhering to the one electrode needle Nm can be scraped off by a tip of the cleaning brush 71m.
Similarly, a plurality of cleaning positions Lp arrayed in the circumferential direction Dc are provided, and the plurality of cleaning positions Lp correspond to the plurality of electrode needles Np, respectively. Then, the cleaning brush 71p is located at one cleaning position Lp corresponding to one electrode needle Np to be cleaned among the plurality of electrode needles Np, thereby coming into contact with the one electrode needle Np. In particular, the motor 72 causes the cleaning brush 71p in contact with one electrode needle Np at one cleaning position Lp to slightly reciprocate in the circumferential direction Dc, whereby dirt adhering to the one electrode needle Np can be scraped off by a tip of the cleaning brush 71p.
Further, the cleaning unit 7 also includes a brush cleaner 75 that cleans the cleaning brushes 71m and 71p. The brush cleaner 75 includes an accommodation box 751 that accommodates the cleaning brushes 71m and 71p. The accommodation box 751 is open in the circumferential direction Dc (in other words, the Y direction), and the cleaning brushes 71m and 71p can be put into the accommodation box 751 or taken out from the accommodation box 751 by moving the cleaning brushes 71m and 71p in the circumferential direction Dc by the motor 72.
The brush cleaner 75 removes dirt from the cleaning brushes 71m and 71p by sliding contact members provided in the accommodation box 751. That is, in the accommodation box 751, the sliding contact members are provided, respectively, to correspond to openings on both sides in the circumferential direction Dc of the accommodation box 751. Then, the tips of the cleaning brushes 71m and 71p moving in the circumferential direction Dc by the driving force of the motor 72 are slid on the sliding contact members of the brush cleaner 75. As a result, the dirt adhering to the cleaning brushes 71m and 71p is scraped off against by the sliding contact members of the brush cleaner 75, whereby cleaning of the cleaning brushes 71m and 71p is executed. This cleaning is executed when the cleaning brushes 71m and 71p enter the accommodation box 751 and exit the accommodation box 751.
The cleaning unit 7 is supported by the I-shaped part of the fixing base 4 described above. Specifically, the motor 72 is supported by the fixing base 4 at the center of the I-shaped part. Further, the brush cleaner 75 is attached to a part having a flat plate-shape in a bottom portion of the fixing base 4.
The fan unit controller 81 rotates the fan 33 provided in the fan unit 3 to generate air flowing in the air blowing direction Dw in the fan 33. This air flows into the housing 2 from the rear side Xb via the rear wire mesh 125. Furthermore, after passing through the flow path Fw in the housing 2, the air flows out from the housing 2 to the front side Xf via the front wire mesh 115 and the mesh portion 112. The air flowing out from the housing 2 in this manner reaches the object to be neutralized.
The cleaning unit controller 83 causes the cleaning brushes 71m and 71p to clean the electrode needles Nm and Np by controlling a rotational position of the motor 72 of the cleaning unit 7. That is, when cleaning one electrode needle Nm among the plurality of electrode needles Nm, the cleaning unit controller 83 controls the rotational position of the motor 72 to move the cleaning brush 71m to the cleaning position Lm opposing the one electrode needle Nm, and then, cause the cleaning brush 71m to slightly reciprocate in the circumferential direction Dc (a cleaning operation). Further, all of the plurality of electrode needles Nm can be cleaned by executing the cleaning operation while sequentially changing one electrode needle Nm to be cleaned among the plurality of electrode needles Nm. Similarly, when cleaning one electrode needle Np among the plurality of electrode needles Np, the cleaning unit controller 83 controls the rotational position of the motor 72 to move the cleaning brush 71p to the cleaning position Lp opposing the one electrode needle Np, and then, cause the cleaning brush 71p to slightly reciprocate in the circumferential direction Dc (a cleaning operation). Further, all of the plurality of electrode needles Np can be cleaned by executing the cleaning operation while sequentially changing one electrode needle Np to be cleaned among the plurality of electrode needles Np.
As described above, the electrode unit controller 9 is connected to the negative electrode unit 5 by the harness Hm, and is connected to the positive electrode unit 6 by the harness Hp. The electrode unit controller 9 controls the voltage applied to the electrode needle Nm of the negative electrode unit 5 via the harness Hm and the voltage applied to the electrode needle Np of the positive electrode unit 6 via the harness Hp, thereby generating a corona discharge between the tip portion of the electrode needle Nm and the tip portion of the electrode needle Np. Due to this corona discharge, negative ions are generated around the tip portion of the electrode needle Nm, and positive ions are generated around the tip portion of the electrode needle Np. Furthermore, the rear wire mesh 125, the positive electrode unit 6, and the negative electrode unit 5 are arrayed in order in the air blowing direction Dw, and the rear wire mesh 125 is connected to the ground G. Therefore, a corona discharge is generated between the electrode needle Np and the rear wire mesh 125, and positive ions are generated around the electrode needle Np. Similarly, a corona discharge is generated between the electrode needle Nm and the rear wire mesh 125, and negative ions are generated around the electrode needle Nm.
As described above, the electrode needle Nm and the electrode needle Np protrude to the flow path Fw, and the air generated by the fan 33 passes the tip portions of the electrode needle Nm and the electrode needle Np. Therefore, the negative ions generated around the tip portion of the electrode needle Nm and the positive ions generated around the tip portion of the electrode needle Np advance to the front side Xf with the air passing through the flow path Fw in the air blowing direction Dw. Further, the fan 33 that generates the air is located on the front side Xf of the positive electrode unit 6 and the negative electrode unit 5, in other words, on the downstream side in the air blowing direction Dw. Therefore, the negative ions and the positive ions flow out from the housing 2 to the front side Xf via the front wire mesh 115 and the mesh portion 112 after being stirred by the fan 33.
That is, 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 opposing the first electrode needle Nm, thereby executing the cleaning operation on this electrode needle Nm. At this time, the cleaning brushes 71m and 71p moving from the accommodation box 751 to the cleaning position Lm are slid on the sliding contact members of the brush cleaner 75, whereby the cleaning of the cleaning brushes 71m and 71p is executed. Further, when the cleaning operation for the last (eighth) 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 opposing the last electrode needle Np to the accommodation box 751. At this time, the cleaning brushes 71m and 71p moving from the cleaning position Lp to the accommodation box 751 are slid on the sliding contact members of the brush cleaner 75, whereby the cleaning of the cleaning brushes 71m and 71p is executed. Incidentally, the cleaning unit controller 83 make speeds of the cleaning brushes 71m and 71p at the time of taking out the cleaning brushes 71m and 71p from the accommodation box 751 slower than speeds of the cleaning brushes 71m and 71p at the time of putting the cleaning brushes 71m and 71p into the accommodation box 751.
In Step S102, the fan unit controller 81 starts rotation of the fan 33 to generate air in the air blowing direction Dw. In Step S103, the electrode unit controller 9 starts applying a voltage to the electrode needles Nm of the negative electrode unit 5 and applying a voltage to the electrode needles Np of the positive electrode unit 6. As a result, a negative DC voltage Vm lower than a voltage of the ground G is applied to the electrode needles Nm, and a positive DC voltage Vp higher than the voltage of the ground G is applied to the electrode needles Np.
Further, the rear wire mesh 125 is connected to the 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 corona discharges respectively generated by the potential difference Vm, the potential difference Vp, and the potential difference Vpm. The negative ions and the positive ions thus generated advance in the air blowing direction Dw by the air and are released from the static eliminator 1 to the front side Xf (a static elimination operation). Note that the cleaning unit controller 83 controls the rotational position of the motor 72 to locate the cleaning brushes 71m and 71p in the accommodation box 751 during execution of the static elimination operation.
In the voltage control in Step S104, feedback control for controlling ion balance in a long term and a short term is executed. Details of this voltage control will be described later with reference to
The negative polarity high voltage power supply 92 is a transformer having a primary-side circuit 921 and a secondary-side circuit 922. A voltage signal Vim is input to the primary-side circuit 921, and the secondary-side circuit 922 is connected to each of the electrode needles Nm of the negative electrode unit 5 by the harness Hm. Then, the voltage Vm corresponding to the voltage signal Vim input to the primary-side circuit 921 is applied to each of the electrode needles Nm from the secondary-side circuit 922 via the harness Hm.
The positive polarity high voltage power supply 93 is a transformer having a primary-side circuit 931 and a secondary-side circuit 932. A voltage signal Vip is input to the primary-side circuit 931, and the secondary-side circuit 932 is connected to each of the electrode needles Np of the positive electrode unit 6 by the harness Hp. Then, the voltage Vp corresponding to the voltage signal Vip input to the primary-side circuit 931 is applied to each of the electrode needles Np from the secondary-side circuit 932 via the harness Hp.
In the housing 2, the above-described ground G (internal ground) is provided. The rear frame 25 made of the antistatic resin in the housing 2 is short-circuited to the ground G. Note that a mode of electrically connecting the rear frame 25 and the ground G is not limited to the short circuit, and these may be connected via a resistor.
Further, the electrode unit controller 9 includes: a ground electrode Te short-circuited to an earth E (external ground); and a low-response detection circuit 94 provided between the ground electrode Te and the ground G. The low-response detection circuit 94 includes a detection resistor R94 that connects the ground electrode Te and the ground G. The detection resistor R94 is provided to detect a current Id1 flowing into the static eliminator 1 from the earth E via the ground electrode Te. That is, when there is a difference between the amount of the negative ions and the amount of the positive ions released from the static eliminator 1, an electric charge corresponding to the difference flows from the earth E into the ground electrode Te, and the current Id1 due to the electric charge flows to the detection resistor R94. As a result, a voltage Vd1 corresponding to the current Id1 is generated at a detection point 941 between the detection resistor R94 and the ground G. In this manner, the low-response detection circuit 94 converts the current Id1, generated by the electric charge flowing into the housing 2 from the earth E via the ground electrode Te, into the voltage Vd1 by the detection resistor R94. In other words, the low-response detection circuit 94 detects the voltage Vd1 indicating ion balance between the negative ions and the positive ions generated by the static eliminator 1 and absorbed by the earth E.
Furthermore, the electrode unit controller 9 includes a high-response detection circuit 95 provided between the front wire mesh 115 and the ground G. The high-response detection circuit 95 includes a detection resistor R95 that connects the front wire mesh 115 and the ground G. The detection resistor R95 is provided to detect a current Idh flowing from the front wire mesh 115 to the ground G. That is, the negative ions and the positive ions generated around the electrode needle Nm and the electrode needle Np move in the air blowing direction Dw and arrive at the front wire mesh 115. The negative ions and the positive ions that have arrived at the front wire mesh 115 in this manner are partially absorbed by the front wire mesh 115. Therefore, an electric charge corresponding to a difference between the amount of the negative ions and the amount of the positive ions absorbed by the front wire mesh 115 flows from the front wire mesh 115 toward the ground G, and the current Idh due to this electric charge flows to the detection resistor R95. As a result, a voltage Vdh corresponding to the current Idh is generated at a detection point 951 between the detection resistor R95 and the front wire mesh 115. In this manner, the high-response detection circuit 95 converts the current Idh, generated by the electric charge flowing from the front wire mesh 115 to the ground G, into the voltage Vdh by the detection resistor R95. In other words, the high-response detection circuit 95 detects the voltage Vdh indicating ion balance between the negative ions and the positive ions generated by the static eliminator 1 and absorbed by the front wire mesh 115.
Here, a resistance value of the detection resistor R94 of the low-response detection circuit 94 is larger than a resistance value of the detection resistor R95 of the high-response detection circuit 95. Further, the capacitance of the earth E is larger than the capacitance of the front wire mesh 115. Therefore, a time constant of the high-response detection circuit 95 is lower than a time constant of the low-response detection circuit 94, in other words, a response speed of the high-response detection circuit 95 is faster than a response speed of the low-response detection circuit 94. That is, the high-response detection circuit 95 detects a fluctuation of a high frequency out of fluctuations of the ion balance, and the low-response detection circuit 94 detects a fluctuation of a low frequency lower than the high frequency out of the fluctuations of the ion balance.
The electrode unit controller 9 controls the ion balance by executing feedback control on the voltages Vm and Vp to be applied to the electrode needles Nm and Np based on the fluctuations of the ion balance detected by the low-response detection circuit 94 and the high-response detection circuit 95. Specifically, the electrode unit controller 9 includes a second balance control unit 96 that controls balance (ion balance) between the negative ions and the positive ions generated by the application of the voltages Vp and Vm to the electrode needles Np and Nm so as to suppress the fluctuations (wobble) of the ion balance, and the feedback control is executed by the second balance control unit 96.
More specifically, the low-response detection circuit 94 outputs the voltage Vd1 indicating the fluctuation of the ion balance in the low frequency to the first balance control unit 912 of the CPU 91. The first balance control unit 912 holds a target voltage Vt1 which is a target value of the voltage Vd1, generates a voltage signal Vs according to a difference between the voltage Vd1 and the target voltage Vt1, and outputs the voltage signal Vs to the second balance control unit 96. Incidentally, the target voltage Vt1 is set to zero volt. That is, a target state is a state in which the amount of the negative ions and the amount of the positive ions released from the static eliminator 1 become equal to each other and the electric charge flowing from the earth E into the static eliminator 1 becomes zero.
Further, the high-response detection circuit 95 outputs the voltage Vdh indicating the fluctuation of the ion balance in the high frequency to the second balance control unit 96. In regard to this, the second balance control unit 96 holds a target voltage Vth which is a target value of the voltage Vdh, generates the voltage signal Vim, which is a control signal for performing the feedback control of the voltage Vm according to a difference between the voltage Vdh and the target voltage Vth and the voltage signal Vs, and outputs the voltage signal Vim to the primary-side circuit 921 of the negative polarity high voltage power supply 92. Incidentally, the target voltage Vth is set to not zero volt but a voltage shifted from zero by a predetermined offset voltage. That is, there is a difference between the ease of absorption of the negative ions by the front wire mesh 115 and the ease of absorption of the positive ions by the front wire mesh 115. Therefore, in a target state in which the equal amounts of the negative ions and the positive ions arrive at the front wire mesh 115, the current Idh does not become zero, and the voltage Vdh is shifted by an offset voltage Vo (offset amount) from the voltage (zero volt) of the ground G. Therefore, the target voltage Vth of the voltage Vdh is set to the offset voltage Vo. Note that the offset voltage Vo is set in the second balance control unit 96 according to the voltage signal Vs reflecting a change in a generation ratio between positive ions and negative ions due to a state change (wear or the like) in the electrode needles Np and Nm.
In this manner, the feedback control for converging the voltage Vd1 toward the target voltage Vt1 and the feedback control for converging the voltage Vdh toward the target voltage Vth are executed. In other words, the feedback control for converging the current Id1 to a target current It1 (=Vt1/R97) and the feedback control for converging the current Idh to a target current Ith (=Vth/R95) are executed. Note that the second balance control unit 96 that executes such control may be configured using an analog circuit such as an operational amplifier or may be configured using a digital circuit such as a processor.
Further, the electrode unit controller 9 executes control for applying voltages Vp and Vm, which are necessary and sufficient for the electrode needles Np and Nm to generate the corona discharges, to the electrode needles Np and Nm using the rear wire mesh 125. More specifically, since the rear wire mesh 125 is short-circuited to the ground G, the electric charge generated in the rear wire mesh 125 flows from the rear wire mesh 125 to the ground G. Note that a mode of electrically connecting the rear wire mesh 125 and the ground G is not limited to the short circuit, and these may be connected via a resistor.
Specifically, along a circuit formed by a corona discharge between the electrode needle Nm and the rear wire mesh 125, a current Irn corresponding to an electric charge generated by the corona discharge flows from the rear wire mesh 125 to the ground G. Further, along a circuit formed by a corona discharge between the electrode needle Np and the rear wire mesh 125, a current Irp corresponding to an electric charge generated by the corona discharge flows from the rear wire mesh 125 to the ground G. On the other hand, the secondary-side circuit 922 of the negative polarity high voltage power supply 92 is connected to the ground G, and the secondary-side circuit 932 of the positive polarity high voltage power supply 93 is connected to the ground G. Therefore, a current Ign mainly including the current Irn reaching the ground G from the rear wire mesh 125 flows from the ground G to the secondary-side circuit 922, and a current Igp mainly including the current Irp reaching the ground G from the rear wire mesh 125 flows from the ground G to the secondary-side circuit 932.
Further, the electrode unit controller 9 also includes a discharge amount detection circuit 97 provided between the secondary-side circuit 932 of the positive polarity high voltage power supply 93 and the ground G. The discharge amount detection circuit 97 includes a detection resistor R97 that connects the secondary-side circuit 932 and the ground G. Therefore, the current Igp flowing from the ground G to the secondary-side circuit 932 flows through the detection resistor R97. As a result, a voltage Vgp corresponding to the current Igp is generated at a detection point 971 between the detection resistor R97 and the secondary-side circuit 932. As described above, the discharge amount detection circuit 97 converts the current Igp, which flows from the rear wire mesh 125 to the secondary-side circuit 932 of the positive polarity high voltage power supply 93 via the ground G, into the voltage Vgp by the detection resistor R97. In other words, the discharge amount detection circuit 97 detects the voltage Vgp indicating an amount of positive ions generated in response to the application of the voltage Vp to the electrode needle Np.
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 a target voltage Vtp which is a target value of the voltage Vgp, generates the voltage signal Vip which is a control signal for performing the feedback control of the voltage Vp according to a difference between the voltage Vgp and the target voltage Vtp, and outputs the voltage signal Vip to the primary-side circuit 931 of the positive polarity high voltage power supply 93. As a result, the feedback control for converging the voltage Vgp toward the target voltage Vtp is executed. As a result, the positive ions in the amount corresponding to the target voltage Vtp are generated around the electrode needle Np. Note that, as described above, the second balance control unit 96 or the like also executes the feedback control to balance the generation amount of negative ions and the generation amount of the positive ions. Therefore, the negative ions are generated around the electrode needle Nm so as to follow the positive ions generated around the electrode needle Np. As a result, the negative ions in the amount corresponding to the target voltage Vtp are generated around the electrode needle Nm. Such control increases the voltages to be applied to the electrode needles Nm and Np in accordance with the progress of wear of the electrode needles Nm and Np, and the amount of negative ions and the amount of positive ions generated in accordance with the corona discharges by the electrode needles Nm and Np are maintained constant.
In the static eliminator 1 described above, the electrode needle Np and the electrode needle Nm (an ion generator) that generate the positive ions and negative ions, and the positive polarity high voltage power supply 93 and the negative polarity high voltage power supply 92 (a high voltage application unit) that apply the voltage Vp (a positive polarity high voltage) and the voltage Vm (a negative polarity high voltage) to the electrode needle Np and the electrode needle Nm are provided. Then, the positive ions are generated around the electrode needle Np when the positive polarity high voltage power supply 93 applies the voltage Vp to the electrode needle Np, and the negative ions are generated around the electrode needle Nm when the negative polarity high voltage power supply 92 applies the voltage Vm to the electrode needle Nm. Further, the current Id1 (a first ion current) flowing between the earth E and the static eliminator 1 via the ground electrode Te is detected, and the feedback control is executed on the negative polarity high voltage power supply 92 such that the current Id1 becomes the target current It1 (a first target value). The long-term ion balance can be appropriately controlled by the feedback control based on the current Id1. Furthermore, the front wire mesh 115 functioning as a detection electrode different from the ground electrode Te is arranged at a position where the positive ions and the negative ions generated by the electrode needle Np and the electrode needle Nm arrive. Then, the current Idh (a second ion current) generated by the positive ions and the negative ions arriving at the front wire mesh 115 is detected, and the feedback control is executed on the negative polarity high voltage power supply 92 such that the current Idh becomes the target current Ith (a second target value). The short-term ion balance can be appropriately controlled by the feedback control based on the current Idh. Thus, it is possible to appropriately control both the long-term ion balance and the short-term ion balance.
Further, the low-response detection circuit 94 (a first detection circuit) has the detection resistor R94 (a first resistor) through which the current Id1 flows, and detects the current Id1 based on the voltage Vd1 (a first voltage) generated in the detection resistor R94 due to the flow of the current Id1. Further, the high-response detection circuit 95 (a second detection circuit) has the detection resistor R95 (a second resistor) through which the current Idh flows, and detects the current Idh based on the voltage Vdh (a second voltage) generated in the detection resistor R95 due to the flow of the current Idh. At this time, the resistance value of the detection resistor R94 is larger than the resistance value of the detection resistor R95. In such a configuration, since the resistance value of the detection resistor R94 is larger than the resistance value of the detection resistor R95, the responsiveness of a system that detects the current Idh by the detection resistor R94 can be made higher than the responsiveness of a system that detects the current Id1 by the detection resistor R95. Thus, the long-term ion balance (in other words, a low frequency component in the ion balance) can be appropriately controlled based on the current Id1 detected by the detection resistor R94, and the short-term ion balance (in other words, a high frequency component in the ion balance) can be appropriately controlled based on the current Idh detected by the detection resistor R95.
Further, the fan 33 that generates air flowing in the air blowing direction Dw is provided, and the front wire mesh 115 is arranged on the downstream side of the electrode needle Np and the electrode needle Nm in the air blowing direction Dw. In such a configuration, the positive ions and negative ions generated by the electrode needle Np and the electrode needle Nm can reliably arrive at the front wire mesh 115 by the air in the air blowing direction Dw generated by the fan 33.
Further, the fan 33 is arranged between the electrode needles Np and Nm and the front wire mesh 115 in the air blowing direction Dw. In such a configuration, the positive ions and negative ions generated by the electrode needle Np and the electrode needle Nm arrive at the front wire mesh 115 in a state of being uniformly dispersed by stirring of the fan 33. Therefore, the current Idh can be stably detected.
Further, the target current Ith of the current Idh is the value shifted from zero by the predetermined offset amount (=Vo/R95). That is, in a case where the same amounts of the positive ions and the negative ions arrive at the front wire mesh 115, the value of the current Idh does not become zero due to characteristics of the front wire mesh 115, and the current Idh has a certain offset amount. Therefore, when this offset amount is set as the target current Ith, the short-term ion balance can be appropriately controlled.
Further, the electrode needle Np (a positive electrode needle) having the tip portion that generates the corona discharge in response to the application of the voltage Vp and the electrode needle Nm (a negative electrode needle) having the tip portion that generates the corona discharge in response to the application of the voltage Vm are provided, and the positive ions are generated by the corona discharge due to the electrode needle Np, and the negative ions are generated by the corona discharge due to the electrode needle Nm. Further, the positive polarity high voltage power supply 93 (a positive polarity high voltage application circuit) that is connected to the electrode needle Np and applies the voltage Vp to the electrode needle Np and the negative polarity high voltage power supply 92 (a negative polarity high voltage application circuit) that is connected to the electrode needle Nm and applies the voltage Vm to the electrode needle Nm are provided. In such a configuration, the ion balance between the positive ions generated by the corona discharge due to the electrode needle Np and the negative ions generated by the corona discharge due to the electrode needle Nm can be appropriately controlled in the long term and the short term.
Further, the discharge amount detection circuit 97 (an ion amount detector) that detects the voltage Vgp indicating the amount of the positive ions generated by the corona discharge of the electrode needle Np (one electrode needle) is provided. Then, the high voltage control unit 911 executes the feedback control based on the voltage Vgp (the amount of ions) detected by the discharge amount detection circuit 97 with respect to the voltage Vp applied to the electrode needle Np from 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 (amount corresponding to the target voltage Vtp). Further, the second balance control unit 96 (a feedback control unit) executes, on the negative polarity high voltage power supply 92 (the other high voltage application circuit), the feedback control for controlling the current Id1 detected by the low-response detection circuit 94 to be the target current It1 and the feedback control for controlling the current Idh detected by the high-response detection circuit 95 to be the target current Ith. In such a configuration, control for generating a certain amount of ions regardless of the progress of wear of the electrode needles Np and Nm is executed on the positive polarity high voltage power supply 93, and control for realizing the appropriate ion balance is executed on the negative polarity high voltage power supply 92. In this manner, it is possible to simplify control by dividing targets of the control according to contents of the control.
As described above, in the present embodiment, the static eliminator 1 corresponds to an example of a “static eliminator” of the invention; the front wire mesh 115 corresponds to an example of a “detection electrode” of the invention; the fan 33 corresponds to an example of a “fan” of the 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 a “high voltage application unit” of the invention; the negative polarity high voltage power supply 92 corresponds to an example of a “negative polarity high voltage application circuit” of the invention; the positive polarity high voltage power supply 93 corresponds to an example of a “positive polarity high voltage application circuit” of the invention; the low-response detection circuit 94 corresponds to an example of a “first detection circuit” of the invention; the high-response detection circuit 95 corresponds to an example of a “second detection circuit” of the invention; the high voltage control unit 911 corresponds to an example of a “high voltage control unit” of the invention; the first balance control unit 912 and the second balance control unit 96 cooperate to function as an example of a “feedback control unit” of the invention; the discharge amount detection circuit 97 corresponds to an example of an “ion amount detector” of the invention; the air blowing direction Dw corresponds to an example of a “air blowing direction” of the invention; the earth E corresponds to an example of an “earth” of the invention; the ground electrode Te corresponds to an example of a “ground electrode” of the invention; the current Id1 corresponds to an example of a “first ion current” of the invention; the current Idh corresponds to an example of a “second ion current” of the invention; the target current It1 corresponds to an example of a “first target value” of the invention; the target current Ith corresponds to an example of a “second target value” of the invention; the electrode needles Np and Nm correspond to examples of an “ion generator” of the invention; the electrode needle Np corresponds to an example of a “positive electrode needle” of the invention; the electrode needle Nm corresponds to an example of a “negative electrode needle” of the invention; the detection resistor R94 corresponds to an example of a “first resistor” of the invention; the detection resistor R95 corresponds to an example of a “second resistor” of the invention; the voltage Vp corresponds to an example of a “positive polarity high voltage” of the invention; the voltage Vm corresponds to an example of a “negative polarity high voltage” of the invention; the voltage Vd1 corresponds to an example of a “first voltage” of the invention; and the voltage Vdh corresponds to an example of a “second voltage” of the invention.
Note that the invention is not limited to the above-described embodiments and various modifications can be made to those described above without departing from the gist thereof. For example, the first unit frame 51 and the second unit frame 61 do not need to have an arc shape, and may have a circular shape.
Further, an arrangement mode 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.
Further, the number or the arrangement mode of the electrode needles Nm and Np may be appropriately changed.
Further, an arrangement order of the negative electrode unit 5 and the positive electrode unit 6 in the X direction may be reversed.
Further, the fan unit 3 may be arranged on the upstream side of the negative electrode unit 5 and the positive electrode unit 6 in the air blowing direction Dw.
Further, specific contents of the control of a generation amount of ions executed by the high voltage control unit 911 are not limited to the above example.
That is, the generation amount of ions may be controlled by performing the feedback control on the voltage Vm based on the current Ign flowing from the ground G to the secondary-side circuit 922 of the negative polarity high voltage power supply 92.
Further, the control for generating the predetermined amount of ions regardless of the progress of wear of the electrode needles Nm and Np (control by the high voltage control unit 911) is executed on the positive polarity high voltage power supply 93, and the control for realizing appropriate ion balance (control by the second balance control unit 96) is executed on the negative polarity high voltage power supply 92. However, the former control may be executed on the negative polarity high voltage power supply 92, and the latter control may be executed on the positive polarity high voltage power supply 93.
Further, two types of the electrode needles Np and Nm to which different DC voltages Vp and Vm are applied are provided, and the positive ions are generated by the electrode needle Np, and the negative ions are generated by the electrode needle Nm. However, positive ions and negative ions may be generated by corona discharges generated by applying an AC voltage, which varies with time between the voltage Vp and the voltage Vm, to one type of electrode needle.
Further, the negative electrode unit 5 and the positive electrode unit 6 may be configured as illustrated in
In this modified example, the negative electrode unit 5 (a first electrode unit) having the plurality of electrode needles Nm (first electrode needles) arrayed in the Y direction (a needle array direction) and the positive electrode unit 6 having the plurality of electrode needles Np (second electrode needles) arrayed in the Y direction are provided. In this manner, the electrode needles Nm and the electrode needles Np are respectively provided in the negative electrode unit 5 and the positive electrode unit 6 different from each other. Therefore, a creepage distance between the electrode needle Nm and the electrode needle Np is a distance of a path from the electrode needle Nm to the electrode needle Np via the negative electrode unit 5 and the positive electrode unit 6. This makes it possible to ensure a wide creepage distance. Further, the negative electrode unit 5 and the positive electrode unit 6 are aligned in the Z direction (a unit array direction), in other words, adjacent to each other in the Z direction. Therefore, a 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 suppressed. As a result, it is possible to suppress the progress of wear of the electrode needle Nm and the electrode needle Np by suppressing the spatial distance between the electrode needle Nm and the electrode needle Np to suppress the voltage required for a corona discharge while preventing the occurrence of abnormal discharge by securing the creepage distance between the electrode needle Nm and the electrode needle Np.
Further, the static eliminator 1 described above is provided with the system performing the feedback control of ion balance in the long term and the system performing the feedback control of ion balance in the short term. A specific configuration for executing such two feedback control systems is not limited to the example of
Further, second ion balance 984 indicating ion balance at a position (for example, the inner side of the front cover 11) different from the first ion balance 982 is detected, and the second ion balance 984 is fed back to the ion output control 981 by a feedback loop 985. The ion output control 981 executes short-term feedback control (that is, feedback control with a high response speed) based on the second ion balance 984 on the ion balance released from the ion output control 981.
That is, first feedback control based on the first ion balance 982 and second feedback control based on the second ion balance 984 are executed, and the responsiveness of the second feedback control is higher than the responsiveness of the first feedback control. As a result, the ion balance can be appropriately maintained in the long term and the short term.
Further, an ion balance sensor illustrated in
Note that, in a case where the ion balance sensor 99 is used for the electrode unit controller 9 in
The invention is applicable to all the techniques for releasing ions generated by applying a voltage to an electrode to an object to eliminate static electricity of the object.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-142588 | Sep 2022 | JP | national |
