Provided is an ion generator that has a potential sensor provided integrally inside the main body of the ion generator, and that can measure, with the potential sensor, an electric field that reaches the potential sensor from a member from which static charge is to be eliminated, without being affected by an electric field between a discharge electrode and an opposing electrode. This ion generator comprises a discharge electrode, an opposing electrode, and a main body part including these electrodes, the ion generator sending out, toward a member from which static charge is to be eliminated, air ions generated by applying a high voltage between the electrodes. A potential sensor that measures the potential of the member from which static charge is to be eliminated is provided integrally to the main body part, and a projecting electrostatic-shielding plate that projects from the main body part is provided between the potential sensor and a discharge part constituted by the discharge electrode and the opposing electrode.
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1. An ion generator that blows air ions generated by applying a high voltage to a discharge unit including discharge electrodes and counter electrodes, toward a charged member, the ion generator comprising:
a main body comprising:
a potential sensor housing portion;
a potential sensor accommodated in the potential sensor housing portion and structured to measure potential of the charged member;
a detection window communicating with the potential sensor housing portion; and
a blow-off opening to blow-off the air ions; and
a projecting electrostatic shield plate disposed between the discharge unit and the potential sensor to project from the main body unit;
wherein the discharge unit is attached to the main body.
2. The ion generator according to
3. The ion generator according to
an aperture window communicating with the detection window is formed in the potential sensor to take in an electric field from the charged member.
4. The ion generator according to
a plurality of the discharge electrodes is disposed at intervals along the blow-off opening, and
the projecting electrostatic shield plate intervenes between any of the discharge electrodes and the aperture window.
5. The ion generator according to
6. The ion generator according to
7. The ion generator according to
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This is a U.S. national stage of application No. PCT/JP2014/060242, filed on Apr. 9, 2014. Priority under 35 U.S.C. §119(a) and 35 U.S.C. §365(b) is claimed from Japanese Patent Applications No. 2013-083022 filed on Apr. 11, 2013, the disclosure of which is also incorporated herein by reference.
The present invention relates to an ion generator that neutralizes charge of an electrically-charged body as an object required to be electrically neutralized (hereinafter “charged member”). The ion generator blows positive or negative air ions generated by corona discharge against the charged member. The present invention relates to, especially an ion generator having an integral potential sensor integrally provided therewith.
The ion generator is called ionizer or static charge eliminator as well. The ion generator blows air ions against a charged target and eliminates charge. In a manufacture line in which manufacture and assembly of electronic components are conducted, electronic components and manufacture assembly jigs are charged. The electronic components and manufacture assembly jigs are regarded as a charged member, and the ion generator is used. Blowing air ions against the charged member prevents foreign matters from adhering to electronic components by static electricity, prevents electronic components from being destroyed by static electricity, and prevents foreign matters from adhering to jigs.
It is known to measure the potential of the charged member, by using a potential sensor (see, for example, Patent Literatures 1 and 2). If such a potential sensor is used together with the ion generator, it is possible to eliminate charge in the charged member, while measuring the potential of the charged member by using the potential sensor. Such a potential sensor is usually attached separately from the ion generator or externally to the ion generator and used.
{PTL 1} Japan Unexamined Patent Application Publication 2012-242094
{PTL 2} Japan Unexamined Patent Application Publication 2010-85393
In a case where the ion generator and the potential sensor are provided separately, the installation space is large. On the other hand, in a case where the ion generator and the potential sensor are provided integrally, the installation space is small. If the ion generator and the potential sensor are provided integrally, however, a problem is posed. For example, since a discharge electrode and an opposite electrode are disposed near the potential sensor, an electric field between the discharge electrode and the opposite electrode with a high voltage applied reaches the potential sensor. The electric field is superposed on an electric field that reaches the potential sensor from the charged member, i.e., an electric field to be measured, and becomes noise. Therefore, it is not possible to measure the potential of the charged member, accurately.
An object of the present invention is to provide, an ion generator that measures potential of a charged member, by using a potential sensor without being influenced by an electric field between a discharge electrode and an opposite electrode, i.e., noise, although the ion generator and the potential sensor are provided integrally.
In order to solve the problem, the present invention provides an ion generator that blows air ions generated by applying a high voltage to a discharge unit including discharge electrodes and opposite electrodes, toward a charged member. The ion generator includes a potential sensor provided integrally in a main body unit to measure potential of the charged member, and a projecting electrostatic shield plate disposed between the discharge unit and the potential sensor to project from the main body unit.
It is possible to set a projection length of the projecting electrostatic shield plate in a range of 8 to 10 mm.
An aperture window is formed in the potential sensor to take in an electric field from the charged member. It is possible to set a distance from the projecting electrostatic shield plate to the aperture window in the potential sensor equal to 2 mm or less.
A blow-off opening is formed in the main body unit to blow off the air ions. A plurality of the discharge electrodes is disposed at intervals along the blow-off opening. It is possible to cause the projecting electrostatic shield plate to intervene between any of the discharge electrodes and the aperture window.
It is possible to cause the blow-off opening and the aperture window to be disposed on the same plane in the main body.
In the ion generator according to the present invention, the potential sensor is provided integrally in the main body unit. Potential of the charged member is measured by the potential sensor. The discharge unit includes the discharge electrodes and the opposite electrodes. The projecting electrostatic shield plate is provided between the discharge unit and the potential sensor. The projecting electrostatic shield plate projects toward an ion blow-off direction from the main body unit. The high voltage is applied between the discharge electrode and the opposite electrode, and an electric field is generated. The electric field is shielded by the projecting electrostatic shield plate, and the electric field does not reach the potential sensor. Therefore, the potential of the charged member is measured by the potential sensor without being influenced by the electric field between the discharge electrode and the opposite electrode, i.e., noise.
Hereafter, an ion generator according to an embodiment of the present invention will be described in detail with reference to the drawings. “Up-down direction,” “left/right direction (width direction),” and “depth direction” used in the following description refer to directions viewed from a front side where the front side (surface side) is this side in
The whole of an ion generator 1 is illustrated in
The main body unit 10 is formed into the shape of nearly a rectangular parallelepiped, and the main body unit 10 extends in the left/right direction. As illustrated in
As illustrated in
As illustrated in
As illustrated in
As illustrated in
A top face cover 14 is provided over the air supply chamber 13 and the discharge electrode unit mounting portion 12. As illustrated in
As illustrated in
On the other hand, as illustrated in
As illustrated in
As illustrated in
As illustrated in
As illustrated in
Power is supplied from an external power supply to the ion generator 1 via a power supply cable 27 (see
As illustrated in
The potential sensor unit 40 includes a potential sensor 41 and a power supply unit (not illustrated) that supplies power to the potential sensor 41. The potential sensor 41 and the power supply unit are attached within the potential sensor unit housing portion 18.
As illustrated in
A rectangular shaped aperture window 113 is formed in the electrostatic shield plate 43. As illustrated in
As illustrated in
As illustrated in
A fixed shutter 115 made of a conductive material is attached to the printed circuit board 111. The fixed shutter 115 covers the detection electrode 114. A main body portion 116 of the fixed shutter 115 is provided in parallel with the electrode portion 114c of the detection electrode 114. The main body portion 116 is formed into a nearly rectangular shape. Side wall portions 117 and end wall portions 118 are bent from the main body portion 116 at right angles and are integral with the main body portion 116. As illustrated in
Aperture slits 119 are formed in the main body portion 116 of the fixed shutter 115. The aperture slits 119 extend in the lengthwise direction (left/right direction) of the electrostatic shield plate 43. Five aperture slits 119 are formed in a width direction (up-down direction) of the main body portion 116. The aperture slits 119 are disposed at constant intervals.
As illustrated in
A center line (not illustrated) of the aperture slits 119 in the lengthwise direction (left/right direction) is referred to as aperture slit center line. A center line (not illustrated) of the slits 131 and 132 in the lengthwise direction (left/right direction) is referred to as main slit center line. A position of the movable shutter 121 in which the aperture slit center line and the main slit center line coincide with each other is referred to as “full open position.”
A center line in the lengthwise direction (left/right direction) of a shield portion (reference numeral is omitted) existing between two main slits 131 is referred to as main shield portion center line. A center line (not illustrated) in the lengthwise direction (left/right direction) of a shield portion (reference numeral is omitted) existing between a main slit 131 and a subsidiary slit 132 is referred to as subsidiary shield portion center line. A position of the movable shutter 121 in which the aperture slit center line coincides with the main shield portion center line or the subsidiary shield portion center line is referred to as “interruption position.”
The movable shutter 121 is formed of a material having conductivity. The movable shutter 121 reciprocates in an open-close direction (up-down direction). The movable shutter 121 includes a fixed end portion 122 fixed to the printed circuit board 111. Leg pieces 123 are integrally provided on both sides of the fixed end portion 122. The leg pieces 123 are inserted into mounting holes formed in the printed circuit board 111. The fixed end portion 122 of the movable shutter 121 is attached to the printed circuit board 111.
An arm portion 124 is provided integrally in each of the leg pieces 123 in the fixed end portion 122. The arm portion 124 extends to one end side (right side) in the lengthwise direction (left/right direction) of the printed circuit board 111. As illustrated in
At least the main body portion 116 of the fixed shutter 115 is grounded. And at least the main body portion 125 of the movable shutter 121 is also grounded.
As illustrated in
Five main slits 131 are formed in the main body portion 125 in the movable shutter 121. The five main slits 131 correspond to the five aperture slits 119 formed in the fixed shutter 115. The respective main slits 131 extend in the same direction as that of the aperture slits 119. Adjacent main slits 131 are disposed at a constant interval. The interval is the same as that of the aperture slits 119.
The movable shutter 121 conducts reciprocal vibration, and moves between the full open position and the interruption position.
In this way, one subsidiary slit 132 is formed on the outside of the two main slits 131 located at both ends of the reciprocation direction N, i.e., in an extension direction of the reciprocation direction N. During one period of movement of the movable shutter 121, the movable shutter 121 moves from the neutral position illustrated in
A current detection circuit is connected to the detection electrode 114. In a state in which the detection electrode 114 is opposed to a charged substance via the aperture window 113, an alternating current in the range of, for example, 600 to 800 Hz is applied to the coils 129a and 129b to cause the movable shutter 121 to conduct reciprocal vibration. As a result, the aperture slits 119 on the fixed shutter 115 are opened and closed with a frequency that is four times the drive frequency of the movable shutter 121. With this open/close frequency, an electric field between the detection electrode 114 and the charged substance changes, and an alternating voltage is generated in the detection electrode 114.
The projecting electrostatic shield plate 43A provided on the electrostatic shield plate 43 will now be described. In the ion generator 1 with the potential sensor 41 integrally mounted thereon, charge elimination is conducted by blowing generated air ions against the charged member P (see
It is necessary to dispose both the blow-off opening 11 of air ions and the potential sensor 41 to be opposed to the charged member P. Therefore, the discharge unit (the discharge electrodes 21 and the opposite electrodes 23) and the aperture window 113 of the potential sensor 41 are provided on the same plane of the main body unit 10. As a result, not only an electric field from the charged member P but also an electric field between the discharge electrode 21 and the opposite electrode 23, i.e., a discharge electric field reaches the potential sensor 41. The discharge electric field becomes noise. In the present embodiment, the blow-off opening 11 and the aperture window 113 of the potential sensor 41 are provided on the same plane of the main body unit 10. In addition, the projecting electrostatic shield plate 43A is projected and provided between the blow-off opening 11 and the aperture window 113 to conduct electrostatic shielding between the discharge unit and the potential sensor 41.
A length S1 of the forward projection of the projecting electrostatic shield plate 43A influences a noise voltage and a signal voltage of the potential sensor 41. Graphs in
Graphs in
The length of the projecting electrostatic shield plate 43A in the left/right direction is made long enough to be also effective to a plurality of discharge electrodes 21 disposed at intervals along the lengthwise direction of the blow-off opening 11. Relations between the length of the projecting electrostatic shield plate 43A and the distance S2 between the projecting electrostatic shield plate 43A and the aperture window 113 will be described hereafter. When the projection length of the projecting electrostatic shield plate 43A is prolonged gradually from 0 mm to 10 mm, attenuation of the sensor signal is in the range of 0% to at most approximately 20% (the distance S2=2 mm). Whereas attenuation of the noise voltage is in the range of 30% (the distance S2=10 mm) to 50% (the distance S2=2 mm). In other words, the sensor signal attenuates little whereas the attenuation of the noise voltage is large. Especially in a case where the projecting electrostatic shield plate 43A and the aperture window 113 are made close to each other so as to have the distance S2 that is approximately 2 mm and the projection length of the projecting electrostatic shield plate 43A is set equal to 10 mm, attenuation of the sensor signal is approximately 20%. On the other hand, attenuation of the noise voltage is approximately 50%. Therefore, the signal to noise ratio is improved by 0.8÷0.5=1.6, i.e., 60%.
In the ion generator according to the embodiment of the present invention, the potential sensor 41, which measures the potential of the charged member P, is provided integrally in the main body unit 10. In addition, the projecting electrostatic shield plate 43A projecting from the main body unit 10 is provided between the discharge unit formed of the discharge electrodes 21 and the opposite electrodes 23, and the potential sensor 41. Therefore, the electric field between the discharge electrode 21 and the opposite electrode 23 is electrostatically shielded by the projecting electrostatic shield plate 43A. Accordingly, the electric field is hard to reach the potential sensor 41. As a result, superposition of noise caused by the electric field between the discharge electrode 21 and the opposite electrode 23 on a value measured by the potential sensor 41 is suppressed. Therefore, the voltage of the charged member P is measured accurately.
The discharge unit formed of the discharge electrodes 21 and the opposite electrodes 23, and the aperture window 113 of the potential sensor 41 are disposed on the same plane. As a result, a depth dimension L (see
The projection length S1 of the projecting electrostatic shield plate 43A is set in the range of 8 to 10 mm from the aperture window 113 of the potential sensor 41. As compared with the case where the projecting electrostatic shield plate 43A is not provided, therefore, it is possible to decrease the ratio of the noise voltage Vn to Vn0 represented by Vn/Vn0 to a range of 35 to 50%. In addition, the distance S2 from the projecting electrostatic shield plate 43A to the aperture window 113 is set equal to or less than 2 mm. As a result, it is possible to suppress the decrease in the ratio of the signal voltage Vs to Vs0 represented by Vs/Vs0 to approximately 20%.
In addition, the blow-off opening 11 is formed to be long. And a plurality of discharge electrodes 21 is disposed at intervals along the lengthwise direction of the blow-off opening 11. In such a configuration, the projecting electrostatic shield plate 43A is made to intervene between all of the discharge electrodes 21 and the aperture window 113. As a result, it is possible to suppress noise generation effectively.
Heretofore, the ion generator according to the embodiment of the present invention has been described. However, the present invention is not restricted to the embodiment described above, but various modifications and changes can be made on the basis of the technical thought of the present invention.
For example, in the present embodiment, the ion generator 1 having a plurality of discharge electrodes 21 along the lengthwise direction has been described. However, the present invention can also be applied to an ion generator having one discharge electrode 21 (an ion generator that blows off air ions in a spot way).
Onezawa, Kazuyoshi, Fukada, Yoshinari
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Jul 07 2015 | FUKADA, YOSHINARI | Koganei Corporation | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 036749 | /0227 | |
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